MFC r363988:

[FreeBSD/stable/9.git] / contrib / bind9 / lib / isc / unix / socket.c

/*
 * Copyright (C) 2004-2016  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1998-2003  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id$ */

/*! \file */

#include <config.h>

#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/uio.h>

#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_INTTYPES_H
#include <inttypes.h> /* uintptr_t */
#endif

#include <isc/buffer.h>
#include <isc/bufferlist.h>
#include <isc/condition.h>
#include <isc/formatcheck.h>
#include <isc/list.h>
#include <isc/log.h>
#include <isc/mem.h>
#include <isc/msgs.h>
#include <isc/mutex.h>
#include <isc/net.h>
#include <isc/once.h>
#include <isc/platform.h>
#include <isc/print.h>
#include <isc/region.h>
#include <isc/resource.h>
#include <isc/socket.h>
#include <isc/stats.h>
#include <isc/strerror.h>
#include <isc/task.h>
#include <isc/thread.h>
#include <isc/util.h>
#include <isc/xml.h>

#ifdef ISC_PLATFORM_HAVESYSUNH
#include <sys/un.h>
#endif
#ifdef ISC_PLATFORM_HAVEKQUEUE
#include <sys/event.h>
#endif
#ifdef ISC_PLATFORM_HAVEEPOLL
#include <sys/epoll.h>
#endif
#ifdef ISC_PLATFORM_HAVEDEVPOLL
#if defined(HAVE_SYS_DEVPOLL_H)
#include <sys/devpoll.h>
#elif defined(HAVE_DEVPOLL_H)
#include <devpoll.h>
#endif
#endif

#include "errno2result.h"

/* See task.c about the following definition: */
#ifdef BIND9
#ifdef ISC_PLATFORM_USETHREADS
#define USE_WATCHER_THREAD
#else
#define USE_SHARED_MANAGER
#endif  /* ISC_PLATFORM_USETHREADS */
#endif  /* BIND9 */

#ifndef USE_WATCHER_THREAD
#include "socket_p.h"
#include "../task_p.h"
#endif /* USE_WATCHER_THREAD */

#if defined(SO_BSDCOMPAT) && defined(__linux__)
#include <sys/utsname.h>
#endif

/*%
 * Choose the most preferable multiplex method.
 */
#ifdef ISC_PLATFORM_HAVEKQUEUE
#define USE_KQUEUE
#elif defined (ISC_PLATFORM_HAVEEPOLL)
#define USE_EPOLL
#elif defined (ISC_PLATFORM_HAVEDEVPOLL)
#define USE_DEVPOLL
typedef struct {
        unsigned int want_read : 1,
                want_write : 1;
} pollinfo_t;
#else
#define USE_SELECT
#endif  /* ISC_PLATFORM_HAVEKQUEUE */

#ifndef USE_WATCHER_THREAD
#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
struct isc_socketwait {
        int nevents;
};
#elif defined (USE_SELECT)
struct isc_socketwait {
        fd_set *readset;
        fd_set *writeset;
        int nfds;
        int maxfd;
};
#endif  /* USE_KQUEUE */
#endif /* !USE_WATCHER_THREAD */

/*%
 * Maximum number of allowable open sockets.  This is also the maximum
 * allowable socket file descriptor.
 *
 * Care should be taken before modifying this value for select():
 * The API standard doesn't ensure select() accept more than (the system default
 * of) FD_SETSIZE descriptors, and the default size should in fact be fine in
 * the vast majority of cases.  This constant should therefore be increased only
 * when absolutely necessary and possible, i.e., the server is exhausting all
 * available file descriptors (up to FD_SETSIZE) and the select() function
 * and FD_xxx macros support larger values than FD_SETSIZE (which may not
 * always by true, but we keep using some of them to ensure as much
 * portability as possible).  Note also that overall server performance
 * may be rather worsened with a larger value of this constant due to
 * inherent scalability problems of select().
 *
 * As a special note, this value shouldn't have to be touched if
 * this is a build for an authoritative only DNS server.
 */
#ifndef ISC_SOCKET_MAXSOCKETS
#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
#define ISC_SOCKET_MAXSOCKETS 4096
#elif defined(USE_SELECT)
#define ISC_SOCKET_MAXSOCKETS FD_SETSIZE
#endif  /* USE_KQUEUE... */
#endif  /* ISC_SOCKET_MAXSOCKETS */

#ifdef USE_SELECT
/*%
 * Mac OS X needs a special definition to support larger values in select().
 * We always define this because a larger value can be specified run-time.
 */
#ifdef __APPLE__
#define _DARWIN_UNLIMITED_SELECT
#endif  /* __APPLE__ */
#endif  /* USE_SELECT */

#ifdef ISC_SOCKET_USE_POLLWATCH
/*%
 * If this macro is defined, enable workaround for a Solaris /dev/poll kernel
 * bug: DP_POLL ioctl could keep sleeping even if socket I/O is possible for
 * some of the specified FD.  The idea is based on the observation that it's
 * likely for a busy server to keep receiving packets.  It specifically works
 * as follows: the socket watcher is first initialized with the state of
 * "poll_idle".  While it's in the idle state it keeps sleeping until a socket
 * event occurs.  When it wakes up for a socket I/O event, it moves to the
 * poll_active state, and sets the poll timeout to a short period
 * (ISC_SOCKET_POLLWATCH_TIMEOUT msec).  If timeout occurs in this state, the
 * watcher goes to the poll_checking state with the same timeout period.
 * In this state, the watcher tries to detect whether this is a break
 * during intermittent events or the kernel bug is triggered.  If the next
 * polling reports an event within the short period, the previous timeout is
 * likely to be a kernel bug, and so the watcher goes back to the active state.
 * Otherwise, it moves to the idle state again.
 *
 * It's not clear whether this is a thread-related bug, but since we've only
 * seen this with threads, this workaround is used only when enabling threads.
 */

typedef enum { poll_idle, poll_active, poll_checking } pollstate_t;

#ifndef ISC_SOCKET_POLLWATCH_TIMEOUT
#define ISC_SOCKET_POLLWATCH_TIMEOUT 10
#endif  /* ISC_SOCKET_POLLWATCH_TIMEOUT */
#endif  /* ISC_SOCKET_USE_POLLWATCH */

/*%
 * Size of per-FD lock buckets.
 */
#ifdef ISC_PLATFORM_USETHREADS
#define FDLOCK_COUNT            1024
#define FDLOCK_ID(fd)           ((fd) % FDLOCK_COUNT)
#else
#define FDLOCK_COUNT            1
#define FDLOCK_ID(fd)           0
#endif  /* ISC_PLATFORM_USETHREADS */

/*%
 * Maximum number of events communicated with the kernel.  There should normally
 * be no need for having a large number.
 */
#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
#ifndef ISC_SOCKET_MAXEVENTS
#define ISC_SOCKET_MAXEVENTS    64
#endif
#endif

/*%
 * Some systems define the socket length argument as an int, some as size_t,
 * some as socklen_t.  This is here so it can be easily changed if needed.
 */
#ifndef ISC_SOCKADDR_LEN_T
#define ISC_SOCKADDR_LEN_T unsigned int
#endif

/*%
 * Define what the possible "soft" errors can be.  These are non-fatal returns
 * of various network related functions, like recv() and so on.
 *
 * For some reason, BSDI (and perhaps others) will sometimes return <0
 * from recv() but will have errno==0.  This is broken, but we have to
 * work around it here.
 */
#define SOFT_ERROR(e)   ((e) == EAGAIN || \
                         (e) == EWOULDBLOCK || \
                         (e) == EINTR || \
                         (e) == 0)

#define DLVL(x) ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(x)

/*!<
 * DLVL(90)  --  Function entry/exit and other tracing.
 * DLVL(70)  --  Socket "correctness" -- including returning of events, etc.
 * DLVL(60)  --  Socket data send/receive
 * DLVL(50)  --  Event tracing, including receiving/sending completion events.
 * DLVL(20)  --  Socket creation/destruction.
 */
#define TRACE_LEVEL             90
#define CORRECTNESS_LEVEL       70
#define IOEVENT_LEVEL           60
#define EVENT_LEVEL             50
#define CREATION_LEVEL          20

#define TRACE           DLVL(TRACE_LEVEL)
#define CORRECTNESS     DLVL(CORRECTNESS_LEVEL)
#define IOEVENT         DLVL(IOEVENT_LEVEL)
#define EVENT           DLVL(EVENT_LEVEL)
#define CREATION        DLVL(CREATION_LEVEL)

typedef isc_event_t intev_t;

#define SOCKET_MAGIC            ISC_MAGIC('I', 'O', 'i', 'o')
#define VALID_SOCKET(s)         ISC_MAGIC_VALID(s, SOCKET_MAGIC)

/*!
 * IPv6 control information.  If the socket is an IPv6 socket we want
 * to collect the destination address and interface so the client can
 * set them on outgoing packets.
 */
#ifdef ISC_PLATFORM_HAVEIN6PKTINFO
#ifndef USE_CMSG
#define USE_CMSG        1
#endif
#endif

/*%
 * NetBSD and FreeBSD can timestamp packets.  XXXMLG Should we have
 * a setsockopt() like interface to request timestamps, and if the OS
 * doesn't do it for us, call gettimeofday() on every UDP receive?
 */
#ifdef SO_TIMESTAMP
#ifndef USE_CMSG
#define USE_CMSG        1
#endif
#endif

/*%
 * The size to raise the receive buffer to (from BIND 8).
 */
#define RCVBUFSIZE (32*1024)

/*%
 * The number of times a send operation is repeated if the result is EINTR.
 */
#define NRETRIES 10

typedef struct isc__socket isc__socket_t;
typedef struct isc__socketmgr isc__socketmgr_t;

#define NEWCONNSOCK(ev) ((isc__socket_t *)(ev)->newsocket)

struct isc__socket {
        /* Not locked. */
        isc_socket_t            common;
        isc__socketmgr_t        *manager;
        isc_mutex_t             lock;
        isc_sockettype_t        type;
        const isc_statscounter_t        *statsindex;

        /* Locked by socket lock. */
        ISC_LINK(isc__socket_t) link;
        unsigned int            references;
        int                     fd;
        int                     pf;
        char                            name[16];
        void *                          tag;

        ISC_LIST(isc_socketevent_t)             send_list;
        ISC_LIST(isc_socketevent_t)             recv_list;
        ISC_LIST(isc_socket_newconnev_t)        accept_list;
        isc_socket_connev_t                    *connect_ev;

        /*
         * Internal events.  Posted when a descriptor is readable or
         * writable.  These are statically allocated and never freed.
         * They will be set to non-purgable before use.
         */
        intev_t                 readable_ev;
        intev_t                 writable_ev;

        isc_sockaddr_t          peer_address;  /* remote address */

        unsigned int            pending_recv : 1,
                                pending_send : 1,
                                pending_accept : 1,
                                listener : 1, /* listener socket */
                                connected : 1,
                                connecting : 1, /* connect pending */
                                bound : 1, /* bound to local addr */
                                dupped : 1;

#ifdef ISC_NET_RECVOVERFLOW
        unsigned char           overflow; /* used for MSG_TRUNC fake */
#endif

        char                    *recvcmsgbuf;
        ISC_SOCKADDR_LEN_T      recvcmsgbuflen;
        char                    *sendcmsgbuf;
        ISC_SOCKADDR_LEN_T      sendcmsgbuflen;

        void                    *fdwatcharg;
        isc_sockfdwatch_t       fdwatchcb;
        int                     fdwatchflags;
        isc_task_t              *fdwatchtask;
};

#define SOCKET_MANAGER_MAGIC    ISC_MAGIC('I', 'O', 'm', 'g')
#define VALID_MANAGER(m)        ISC_MAGIC_VALID(m, SOCKET_MANAGER_MAGIC)

struct isc__socketmgr {
        /* Not locked. */
        isc_socketmgr_t         common;
        isc_mem_t              *mctx;
        isc_mutex_t             lock;
        isc_mutex_t             *fdlock;
        isc_stats_t             *stats;
#ifdef USE_KQUEUE
        int                     kqueue_fd;
        int                     nevents;
        struct kevent           *events;
#endif  /* USE_KQUEUE */
#ifdef USE_EPOLL
        int                     epoll_fd;
        int                     nevents;
        struct epoll_event      *events;
#endif  /* USE_EPOLL */
#ifdef USE_DEVPOLL
        int                     devpoll_fd;
        isc_resourcevalue_t     open_max;
        unsigned int            calls;
        int                     nevents;
        struct pollfd           *events;
#endif  /* USE_DEVPOLL */
#ifdef USE_SELECT
        int                     fd_bufsize;
#endif  /* USE_SELECT */
        unsigned int            maxsocks;
#ifdef ISC_PLATFORM_USETHREADS
        int                     pipe_fds[2];
#endif

        /* Locked by fdlock. */
        isc__socket_t          **fds;
        int                     *fdstate;
#if defined(USE_EPOLL)
        uint32_t                *epoll_events;
#endif
#ifdef USE_DEVPOLL
        pollinfo_t              *fdpollinfo;
#endif

        /* Locked by manager lock. */
        ISC_LIST(isc__socket_t) socklist;
#ifdef USE_SELECT
        fd_set                  *read_fds;
        fd_set                  *read_fds_copy;
        fd_set                  *write_fds;
        fd_set                  *write_fds_copy;
        int                     maxfd;
#endif  /* USE_SELECT */
        int                     reserved;       /* unlocked */
#ifdef USE_WATCHER_THREAD
        isc_thread_t            watcher;
        isc_condition_t         shutdown_ok;
#else /* USE_WATCHER_THREAD */
        unsigned int            refs;
#endif /* USE_WATCHER_THREAD */
        int                     maxudp;
};

#ifdef USE_SHARED_MANAGER
static isc__socketmgr_t *socketmgr = NULL;
#endif /* USE_SHARED_MANAGER */

#define CLOSED                  0       /* this one must be zero */
#define MANAGED                 1
#define CLOSE_PENDING           2

/*
 * send() and recv() iovec counts
 */
#define MAXSCATTERGATHER_SEND   (ISC_SOCKET_MAXSCATTERGATHER)
#ifdef ISC_NET_RECVOVERFLOW
# define MAXSCATTERGATHER_RECV  (ISC_SOCKET_MAXSCATTERGATHER + 1)
#else
# define MAXSCATTERGATHER_RECV  (ISC_SOCKET_MAXSCATTERGATHER)
#endif

static isc_result_t socket_create(isc_socketmgr_t *manager0, int pf,
                                  isc_sockettype_t type,
                                  isc_socket_t **socketp,
                                  isc_socket_t *dup_socket);
static void send_recvdone_event(isc__socket_t *, isc_socketevent_t **);
static void send_senddone_event(isc__socket_t *, isc_socketevent_t **);
static void free_socket(isc__socket_t **);
static isc_result_t allocate_socket(isc__socketmgr_t *, isc_sockettype_t,
                                    isc__socket_t **);
static void destroy(isc__socket_t **);
static void internal_accept(isc_task_t *, isc_event_t *);
static void internal_connect(isc_task_t *, isc_event_t *);
static void internal_recv(isc_task_t *, isc_event_t *);
static void internal_send(isc_task_t *, isc_event_t *);
static void internal_fdwatch_write(isc_task_t *, isc_event_t *);
static void internal_fdwatch_read(isc_task_t *, isc_event_t *);
static void process_cmsg(isc__socket_t *, struct msghdr *, isc_socketevent_t *);
static void build_msghdr_send(isc__socket_t *, isc_socketevent_t *,
                              struct msghdr *, struct iovec *, size_t *);
static void build_msghdr_recv(isc__socket_t *, isc_socketevent_t *,
                              struct msghdr *, struct iovec *, size_t *);
#ifdef USE_WATCHER_THREAD
static isc_boolean_t process_ctlfd(isc__socketmgr_t *manager);
#endif

/*%
 * The following can be either static or public, depending on build environment.
 */

#ifdef BIND9
#define ISC_SOCKETFUNC_SCOPE
#else
#define ISC_SOCKETFUNC_SCOPE static
#endif

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
                   isc_socket_t **socketp);
ISC_SOCKETFUNC_SCOPE void
isc__socket_attach(isc_socket_t *sock, isc_socket_t **socketp);
ISC_SOCKETFUNC_SCOPE void
isc__socket_detach(isc_socket_t **socketp);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socketmgr_create(isc_mem_t *mctx, isc_socketmgr_t **managerp);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socketmgr_create2(isc_mem_t *mctx, isc_socketmgr_t **managerp,
                       unsigned int maxsocks);
ISC_SOCKETFUNC_SCOPE void
isc__socketmgr_destroy(isc_socketmgr_t **managerp);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_recvv(isc_socket_t *sock, isc_bufferlist_t *buflist,
                 unsigned int minimum, isc_task_t *task,
                  isc_taskaction_t action, void *arg);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_recv(isc_socket_t *sock, isc_region_t *region,
                 unsigned int minimum, isc_task_t *task,
                 isc_taskaction_t action, void *arg);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_recv2(isc_socket_t *sock, isc_region_t *region,
                  unsigned int minimum, isc_task_t *task,
                  isc_socketevent_t *event, unsigned int flags);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_send(isc_socket_t *sock, isc_region_t *region,
                 isc_task_t *task, isc_taskaction_t action, void *arg);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendto(isc_socket_t *sock, isc_region_t *region,
                   isc_task_t *task, isc_taskaction_t action, void *arg,
                   isc_sockaddr_t *address, struct in6_pktinfo *pktinfo);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendv(isc_socket_t *sock, isc_bufferlist_t *buflist,
                  isc_task_t *task, isc_taskaction_t action, void *arg);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendtov(isc_socket_t *sock, isc_bufferlist_t *buflist,
                    isc_task_t *task, isc_taskaction_t action, void *arg,
                    isc_sockaddr_t *address, struct in6_pktinfo *pktinfo);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendtov2(isc_socket_t *sock, isc_bufferlist_t *buflist,
                     isc_task_t *task, isc_taskaction_t action, void *arg,
                     isc_sockaddr_t *address, struct in6_pktinfo *pktinfo,
                     unsigned int flags);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendto2(isc_socket_t *sock, isc_region_t *region,
                    isc_task_t *task,
                    isc_sockaddr_t *address, struct in6_pktinfo *pktinfo,
                    isc_socketevent_t *event, unsigned int flags);
ISC_SOCKETFUNC_SCOPE void
isc__socket_cleanunix(isc_sockaddr_t *sockaddr, isc_boolean_t active);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_permunix(isc_sockaddr_t *sockaddr, isc_uint32_t perm,
                     isc_uint32_t owner, isc_uint32_t group);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_bind(isc_socket_t *sock, isc_sockaddr_t *sockaddr,
                 unsigned int options);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_filter(isc_socket_t *sock, const char *filter);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_listen(isc_socket_t *sock, unsigned int backlog);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_accept(isc_socket_t *sock,
                   isc_task_t *task, isc_taskaction_t action, void *arg);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_connect(isc_socket_t *sock, isc_sockaddr_t *addr,
                    isc_task_t *task, isc_taskaction_t action,
                    void *arg);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_getpeername(isc_socket_t *sock, isc_sockaddr_t *addressp);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_getsockname(isc_socket_t *sock, isc_sockaddr_t *addressp);
ISC_SOCKETFUNC_SCOPE void
isc__socket_cancel(isc_socket_t *sock, isc_task_t *task, unsigned int how);
ISC_SOCKETFUNC_SCOPE isc_sockettype_t
isc__socket_gettype(isc_socket_t *sock);
ISC_SOCKETFUNC_SCOPE isc_boolean_t
isc__socket_isbound(isc_socket_t *sock);
ISC_SOCKETFUNC_SCOPE void
isc__socket_ipv6only(isc_socket_t *sock, isc_boolean_t yes);
#if defined(HAVE_LIBXML2) && defined(BIND9)
ISC_SOCKETFUNC_SCOPE void
isc__socketmgr_renderxml(isc_socketmgr_t *mgr0, xmlTextWriterPtr writer);
#endif

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_fdwatchcreate(isc_socketmgr_t *manager, int fd, int flags,
                          isc_sockfdwatch_t callback, void *cbarg,
                          isc_task_t *task, isc_socket_t **socketp);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_fdwatchpoke(isc_socket_t *sock, int flags);
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_dup(isc_socket_t *sock, isc_socket_t **socketp);
ISC_SOCKETFUNC_SCOPE int
isc__socket_getfd(isc_socket_t *sock);

static struct {
        isc_socketmethods_t methods;

        /*%
         * The following are defined just for avoiding unused static functions.
         */
#ifndef BIND9
        void *recvv, *send, *sendv, *sendto2, *sendtov, *cleanunix, *permunix,
             *filter, *listen, *accept, *getpeername, *isbound;
#endif
} socketmethods = {
        {
                isc__socket_attach,
                isc__socket_detach,
                isc__socket_bind,
                isc__socket_sendto,
                isc__socket_sendto2,
                isc__socket_connect,
                isc__socket_recv,
                isc__socket_recv2,
                isc__socket_cancel,
                isc__socket_getsockname,
                isc__socket_gettype,
                isc__socket_ipv6only,
                isc__socket_fdwatchpoke,
                isc__socket_dup,
                isc__socket_getfd
        }
#ifndef BIND9
        ,
        (void *)isc__socket_recvv, (void *)isc__socket_send,
        (void *)isc__socket_sendv, (void *)isc__socket_sendto2,
        (void *)isc__socket_sendtov,
        (void *)isc__socket_cleanunix, (void *)isc__socket_permunix,
        (void *)isc__socket_filter, (void *)isc__socket_listen,
        (void *)isc__socket_accept, (void *)isc__socket_getpeername,
        (void *)isc__socket_isbound
#endif
};

static isc_socketmgrmethods_t socketmgrmethods = {
        isc__socketmgr_destroy,
        isc__socket_create,
        isc__socket_fdwatchcreate
};

#define SELECT_POKE_SHUTDOWN            (-1)
#define SELECT_POKE_NOTHING             (-2)
#define SELECT_POKE_READ                (-3)
#define SELECT_POKE_ACCEPT              (-3) /*%< Same as _READ */
#define SELECT_POKE_WRITE               (-4)
#define SELECT_POKE_CONNECT             (-4) /*%< Same as _WRITE */
#define SELECT_POKE_CLOSE               (-5)

#define SOCK_DEAD(s)                    ((s)->references == 0)

/*%
 * Shortcut index arrays to get access to statistics counters.
 */
enum {
        STATID_OPEN = 0,
        STATID_OPENFAIL = 1,
        STATID_CLOSE = 2,
        STATID_BINDFAIL = 3,
        STATID_CONNECTFAIL = 4,
        STATID_CONNECT = 5,
        STATID_ACCEPTFAIL = 6,
        STATID_ACCEPT = 7,
        STATID_SENDFAIL = 8,
        STATID_RECVFAIL = 9
};
static const isc_statscounter_t udp4statsindex[] = {
        isc_sockstatscounter_udp4open,
        isc_sockstatscounter_udp4openfail,
        isc_sockstatscounter_udp4close,
        isc_sockstatscounter_udp4bindfail,
        isc_sockstatscounter_udp4connectfail,
        isc_sockstatscounter_udp4connect,
        -1,
        -1,
        isc_sockstatscounter_udp4sendfail,
        isc_sockstatscounter_udp4recvfail
};
static const isc_statscounter_t udp6statsindex[] = {
        isc_sockstatscounter_udp6open,
        isc_sockstatscounter_udp6openfail,
        isc_sockstatscounter_udp6close,
        isc_sockstatscounter_udp6bindfail,
        isc_sockstatscounter_udp6connectfail,
        isc_sockstatscounter_udp6connect,
        -1,
        -1,
        isc_sockstatscounter_udp6sendfail,
        isc_sockstatscounter_udp6recvfail
};
static const isc_statscounter_t tcp4statsindex[] = {
        isc_sockstatscounter_tcp4open,
        isc_sockstatscounter_tcp4openfail,
        isc_sockstatscounter_tcp4close,
        isc_sockstatscounter_tcp4bindfail,
        isc_sockstatscounter_tcp4connectfail,
        isc_sockstatscounter_tcp4connect,
        isc_sockstatscounter_tcp4acceptfail,
        isc_sockstatscounter_tcp4accept,
        isc_sockstatscounter_tcp4sendfail,
        isc_sockstatscounter_tcp4recvfail
};
static const isc_statscounter_t tcp6statsindex[] = {
        isc_sockstatscounter_tcp6open,
        isc_sockstatscounter_tcp6openfail,
        isc_sockstatscounter_tcp6close,
        isc_sockstatscounter_tcp6bindfail,
        isc_sockstatscounter_tcp6connectfail,
        isc_sockstatscounter_tcp6connect,
        isc_sockstatscounter_tcp6acceptfail,
        isc_sockstatscounter_tcp6accept,
        isc_sockstatscounter_tcp6sendfail,
        isc_sockstatscounter_tcp6recvfail
};
static const isc_statscounter_t unixstatsindex[] = {
        isc_sockstatscounter_unixopen,
        isc_sockstatscounter_unixopenfail,
        isc_sockstatscounter_unixclose,
        isc_sockstatscounter_unixbindfail,
        isc_sockstatscounter_unixconnectfail,
        isc_sockstatscounter_unixconnect,
        isc_sockstatscounter_unixacceptfail,
        isc_sockstatscounter_unixaccept,
        isc_sockstatscounter_unixsendfail,
        isc_sockstatscounter_unixrecvfail
};
static const isc_statscounter_t fdwatchstatsindex[] = {
        -1,
        -1,
        isc_sockstatscounter_fdwatchclose,
        isc_sockstatscounter_fdwatchbindfail,
        isc_sockstatscounter_fdwatchconnectfail,
        isc_sockstatscounter_fdwatchconnect,
        -1,
        -1,
        isc_sockstatscounter_fdwatchsendfail,
        isc_sockstatscounter_fdwatchrecvfail
};

#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL) || \
    defined(USE_WATCHER_THREAD)
static void
manager_log(isc__socketmgr_t *sockmgr,
            isc_logcategory_t *category, isc_logmodule_t *module, int level,
            const char *fmt, ...) ISC_FORMAT_PRINTF(5, 6);
static void
manager_log(isc__socketmgr_t *sockmgr,
            isc_logcategory_t *category, isc_logmodule_t *module, int level,
            const char *fmt, ...)
{
        char msgbuf[2048];
        va_list ap;

        if (! isc_log_wouldlog(isc_lctx, level))
                return;

        va_start(ap, fmt);
        vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
        va_end(ap);

        isc_log_write(isc_lctx, category, module, level,
                      "sockmgr %p: %s", sockmgr, msgbuf);
}
#endif

static void
socket_log(isc__socket_t *sock, isc_sockaddr_t *address,
           isc_logcategory_t *category, isc_logmodule_t *module, int level,
           isc_msgcat_t *msgcat, int msgset, int message,
           const char *fmt, ...) ISC_FORMAT_PRINTF(9, 10);
static void
socket_log(isc__socket_t *sock, isc_sockaddr_t *address,
           isc_logcategory_t *category, isc_logmodule_t *module, int level,
           isc_msgcat_t *msgcat, int msgset, int message,
           const char *fmt, ...)
{
        char msgbuf[2048];
        char peerbuf[ISC_SOCKADDR_FORMATSIZE];
        va_list ap;

        if (! isc_log_wouldlog(isc_lctx, level))
                return;

        va_start(ap, fmt);
        vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
        va_end(ap);

        if (address == NULL) {
                isc_log_iwrite(isc_lctx, category, module, level,
                               msgcat, msgset, message,
                               "socket %p: %s", sock, msgbuf);
        } else {
                isc_sockaddr_format(address, peerbuf, sizeof(peerbuf));
                isc_log_iwrite(isc_lctx, category, module, level,
                               msgcat, msgset, message,
                               "socket %p %s: %s", sock, peerbuf, msgbuf);
        }
}

#if defined(_AIX) && defined(ISC_NET_BSD44MSGHDR) && \
    defined(USE_CMSG) && defined(IPV6_RECVPKTINFO)
/*
 * AIX has a kernel bug where IPV6_RECVPKTINFO gets cleared by
 * setting IPV6_V6ONLY.
 */
static void
FIX_IPV6_RECVPKTINFO(isc__socket_t *sock)
{
        char strbuf[ISC_STRERRORSIZE];
        int on = 1;

        if (sock->pf != AF_INET6 || sock->type != isc_sockettype_udp)
                return;

        if (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
                       (void *)&on, sizeof(on)) < 0) {

                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "setsockopt(%d, IPV6_RECVPKTINFO) "
                                 "%s: %s", sock->fd,
                                 isc_msgcat_get(isc_msgcat,
                                                ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED,
                                                "failed"),
                                 strbuf);
        }
}
#else
#define FIX_IPV6_RECVPKTINFO(sock) (void)0
#endif

/*%
 * Increment socket-related statistics counters.
 */
static inline void
inc_stats(isc_stats_t *stats, isc_statscounter_t counterid) {
        REQUIRE(counterid != -1);

        if (stats != NULL)
                isc_stats_increment(stats, counterid);
}

static inline isc_result_t
watch_fd(isc__socketmgr_t *manager, int fd, int msg) {
        isc_result_t result = ISC_R_SUCCESS;

#ifdef USE_KQUEUE
        struct kevent evchange;

        memset(&evchange, 0, sizeof(evchange));
        if (msg == SELECT_POKE_READ)
                evchange.filter = EVFILT_READ;
        else
                evchange.filter = EVFILT_WRITE;
        evchange.flags = EV_ADD;
        evchange.ident = fd;
        if (kevent(manager->kqueue_fd, &evchange, 1, NULL, 0, NULL) != 0)
                result = isc__errno2result(errno);

        return (result);
#elif defined(USE_EPOLL)
        struct epoll_event event;
        uint32_t oldevents;
        int ret;
        int op;

        oldevents = manager->epoll_events[fd];
        if (msg == SELECT_POKE_READ)
                manager->epoll_events[fd] |= EPOLLIN;
        else
                manager->epoll_events[fd] |= EPOLLOUT;

        event.events = manager->epoll_events[fd];
        memset(&event.data, 0, sizeof(event.data));
        event.data.fd = fd;

        op = (oldevents == 0U) ? EPOLL_CTL_ADD : EPOLL_CTL_MOD;
        ret = epoll_ctl(manager->epoll_fd, op, fd, &event);
        if (ret == -1) {
                if (errno == EEXIST)
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "epoll_ctl(ADD/MOD) returned "
                                         "EEXIST for fd %d", fd);
                result = isc__errno2result(errno);
        }

        return (result);
#elif defined(USE_DEVPOLL)
        struct pollfd pfd;
        int lockid = FDLOCK_ID(fd);

        memset(&pfd, 0, sizeof(pfd));
        if (msg == SELECT_POKE_READ)
                pfd.events = POLLIN;
        else
                pfd.events = POLLOUT;
        pfd.fd = fd;
        pfd.revents = 0;
        LOCK(&manager->fdlock[lockid]);
        if (write(manager->devpoll_fd, &pfd, sizeof(pfd)) == -1)
                result = isc__errno2result(errno);
        else {
                if (msg == SELECT_POKE_READ)
                        manager->fdpollinfo[fd].want_read = 1;
                else
                        manager->fdpollinfo[fd].want_write = 1;
        }
        UNLOCK(&manager->fdlock[lockid]);

        return (result);
#elif defined(USE_SELECT)
        LOCK(&manager->lock);
        if (msg == SELECT_POKE_READ)
                FD_SET(fd, manager->read_fds);
        if (msg == SELECT_POKE_WRITE)
                FD_SET(fd, manager->write_fds);
        UNLOCK(&manager->lock);

        return (result);
#endif
}

static inline isc_result_t
unwatch_fd(isc__socketmgr_t *manager, int fd, int msg) {
        isc_result_t result = ISC_R_SUCCESS;

#ifdef USE_KQUEUE
        struct kevent evchange;

        memset(&evchange, 0, sizeof(evchange));
        if (msg == SELECT_POKE_READ)
                evchange.filter = EVFILT_READ;
        else
                evchange.filter = EVFILT_WRITE;
        evchange.flags = EV_DELETE;
        evchange.ident = fd;
        if (kevent(manager->kqueue_fd, &evchange, 1, NULL, 0, NULL) != 0)
                result = isc__errno2result(errno);

        return (result);
#elif defined(USE_EPOLL)
        struct epoll_event event;
        int ret;
        int op;

        if (msg == SELECT_POKE_READ)
                manager->epoll_events[fd] &= ~(EPOLLIN);
        else
                manager->epoll_events[fd] &= ~(EPOLLOUT);

        event.events = manager->epoll_events[fd];
        memset(&event.data, 0, sizeof(event.data));
        event.data.fd = fd;

        op = (event.events == 0U) ? EPOLL_CTL_DEL : EPOLL_CTL_MOD;
        ret = epoll_ctl(manager->epoll_fd, op, fd, &event);
        if (ret == -1 && errno != ENOENT) {
                char strbuf[ISC_STRERRORSIZE];
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "epoll_ctl(DEL), %d: %s", fd, strbuf);
                result = ISC_R_UNEXPECTED;
        }
        return (result);
#elif defined(USE_DEVPOLL)
        struct pollfd pfds[2];
        size_t writelen = sizeof(pfds[0]);
        int lockid = FDLOCK_ID(fd);

        memset(pfds, 0, sizeof(pfds));
        pfds[0].events = POLLREMOVE;
        pfds[0].fd = fd;

        /*
         * Canceling read or write polling via /dev/poll is tricky.  Since it
         * only provides a way of canceling per FD, we may need to re-poll the
         * socket for the other operation.
         */
        LOCK(&manager->fdlock[lockid]);
        if (msg == SELECT_POKE_READ &&
            manager->fdpollinfo[fd].want_write == 1) {
                pfds[1].events = POLLOUT;
                pfds[1].fd = fd;
                writelen += sizeof(pfds[1]);
        }
        if (msg == SELECT_POKE_WRITE &&
            manager->fdpollinfo[fd].want_read == 1) {
                pfds[1].events = POLLIN;
                pfds[1].fd = fd;
                writelen += sizeof(pfds[1]);
        }

        if (write(manager->devpoll_fd, pfds, writelen) == -1)
                result = isc__errno2result(errno);
        else {
                if (msg == SELECT_POKE_READ)
                        manager->fdpollinfo[fd].want_read = 0;
                else
                        manager->fdpollinfo[fd].want_write = 0;
        }
        UNLOCK(&manager->fdlock[lockid]);

        return (result);
#elif defined(USE_SELECT)
        LOCK(&manager->lock);
        if (msg == SELECT_POKE_READ)
                FD_CLR(fd, manager->read_fds);
        else if (msg == SELECT_POKE_WRITE)
                FD_CLR(fd, manager->write_fds);
        UNLOCK(&manager->lock);

        return (result);
#endif
}

static void
wakeup_socket(isc__socketmgr_t *manager, int fd, int msg) {
        isc_result_t result;
        int lockid = FDLOCK_ID(fd);

        /*
         * This is a wakeup on a socket.  If the socket is not in the
         * process of being closed, start watching it for either reads
         * or writes.
         */

        INSIST(fd >= 0 && fd < (int)manager->maxsocks);

        if (msg == SELECT_POKE_CLOSE) {
                /* No one should be updating fdstate, so no need to lock it */
                INSIST(manager->fdstate[fd] == CLOSE_PENDING);
                manager->fdstate[fd] = CLOSED;
                (void)unwatch_fd(manager, fd, SELECT_POKE_READ);
                (void)unwatch_fd(manager, fd, SELECT_POKE_WRITE);
                (void)close(fd);
                return;
        }

        LOCK(&manager->fdlock[lockid]);
        if (manager->fdstate[fd] == CLOSE_PENDING) {
                UNLOCK(&manager->fdlock[lockid]);

                /*
                 * We accept (and ignore) any error from unwatch_fd() as we are
                 * closing the socket, hoping it doesn't leave dangling state in
                 * the kernel.
                 * Note that unwatch_fd() must be called after releasing the
                 * fdlock; otherwise it could cause deadlock due to a lock order
                 * reversal.
                 */
                (void)unwatch_fd(manager, fd, SELECT_POKE_READ);
                (void)unwatch_fd(manager, fd, SELECT_POKE_WRITE);
                return;
        }
        if (manager->fdstate[fd] != MANAGED) {
                UNLOCK(&manager->fdlock[lockid]);
                return;
        }
        UNLOCK(&manager->fdlock[lockid]);

        /*
         * Set requested bit.
         */
        result = watch_fd(manager, fd, msg);
        if (result != ISC_R_SUCCESS) {
                /*
                 * XXXJT: what should we do?  Ignoring the failure of watching
                 * a socket will make the application dysfunctional, but there
                 * seems to be no reasonable recovery process.
                 */
                isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                              ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                              "failed to start watching FD (%d): %s",
                              fd, isc_result_totext(result));
        }
}

#ifdef USE_WATCHER_THREAD
/*
 * Poke the select loop when there is something for us to do.
 * The write is required (by POSIX) to complete.  That is, we
 * will not get partial writes.
 */
static void
select_poke(isc__socketmgr_t *mgr, int fd, int msg) {
        int cc;
        int buf[2];
        char strbuf[ISC_STRERRORSIZE];

        buf[0] = fd;
        buf[1] = msg;

        do {
                cc = write(mgr->pipe_fds[1], buf, sizeof(buf));
#ifdef ENOSR
                /*
                 * Treat ENOSR as EAGAIN but loop slowly as it is
                 * unlikely to clear fast.
                 */
                if (cc < 0 && errno == ENOSR) {
                        sleep(1);
                        errno = EAGAIN;
                }
#endif
        } while (cc < 0 && SOFT_ERROR(errno));

        if (cc < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                FATAL_ERROR(__FILE__, __LINE__,
                            isc_msgcat_get(isc_msgcat, ISC_MSGSET_SOCKET,
                                           ISC_MSG_WRITEFAILED,
                                           "write() failed "
                                           "during watcher poke: %s"),
                            strbuf);
        }

        INSIST(cc == sizeof(buf));
}

/*
 * Read a message on the internal fd.
 */
static void
select_readmsg(isc__socketmgr_t *mgr, int *fd, int *msg) {
        int buf[2];
        int cc;
        char strbuf[ISC_STRERRORSIZE];

        cc = read(mgr->pipe_fds[0], buf, sizeof(buf));
        if (cc < 0) {
                *msg = SELECT_POKE_NOTHING;
                *fd = -1;       /* Silence compiler. */
                if (SOFT_ERROR(errno))
                        return;

                isc__strerror(errno, strbuf, sizeof(strbuf));
                FATAL_ERROR(__FILE__, __LINE__,
                            isc_msgcat_get(isc_msgcat, ISC_MSGSET_SOCKET,
                                           ISC_MSG_READFAILED,
                                           "read() failed "
                                           "during watcher poke: %s"),
                            strbuf);
        }
        INSIST(cc == sizeof(buf));

        *fd = buf[0];
        *msg = buf[1];
}
#else /* USE_WATCHER_THREAD */
/*
 * Update the state of the socketmgr when something changes.
 */
static void
select_poke(isc__socketmgr_t *manager, int fd, int msg) {
        if (msg == SELECT_POKE_SHUTDOWN)
                return;
        else if (fd >= 0)
                wakeup_socket(manager, fd, msg);
        return;
}
#endif /* USE_WATCHER_THREAD */

/*
 * Make a fd non-blocking.
 */
static isc_result_t
make_nonblock(int fd) {
        int ret;
        int flags;
        char strbuf[ISC_STRERRORSIZE];
#ifdef USE_FIONBIO_IOCTL
        int on = 1;

        ret = ioctl(fd, FIONBIO, (char *)&on);
#else
        flags = fcntl(fd, F_GETFL, 0);
        flags |= PORT_NONBLOCK;
        ret = fcntl(fd, F_SETFL, flags);
#endif

        if (ret == -1) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
#ifdef USE_FIONBIO_IOCTL
                                 "ioctl(%d, FIONBIO, &on): %s", fd,
#else
                                 "fcntl(%d, F_SETFL, %d): %s", fd, flags,
#endif
                                 strbuf);

                return (ISC_R_UNEXPECTED);
        }

        return (ISC_R_SUCCESS);
}

#ifdef USE_CMSG
/*
 * Not all OSes support advanced CMSG macros: CMSG_LEN and CMSG_SPACE.
 * In order to ensure as much portability as possible, we provide wrapper
 * functions of these macros.
 * Note that cmsg_space() could run slow on OSes that do not have
 * CMSG_SPACE.
 */
static inline ISC_SOCKADDR_LEN_T
cmsg_len(ISC_SOCKADDR_LEN_T len) {
#ifdef CMSG_LEN
        return (CMSG_LEN(len));
#else
        ISC_SOCKADDR_LEN_T hdrlen;

        /*
         * Cast NULL so that any pointer arithmetic performed by CMSG_DATA
         * is correct.
         */
        hdrlen = (ISC_SOCKADDR_LEN_T)CMSG_DATA(((struct cmsghdr *)NULL));
        return (hdrlen + len);
#endif
}

static inline ISC_SOCKADDR_LEN_T
cmsg_space(ISC_SOCKADDR_LEN_T len) {
#ifdef CMSG_SPACE
        return (CMSG_SPACE(len));
#else
        struct msghdr msg;
        struct cmsghdr *cmsgp;
        /*
         * XXX: The buffer length is an ad-hoc value, but should be enough
         * in a practical sense.
         */
        char dummybuf[sizeof(struct cmsghdr) + 1024];

        memset(&msg, 0, sizeof(msg));
        msg.msg_control = dummybuf;
        msg.msg_controllen = sizeof(dummybuf);

        cmsgp = (struct cmsghdr *)dummybuf;
        cmsgp->cmsg_len = cmsg_len(len);

        cmsgp = CMSG_NXTHDR(&msg, cmsgp);
        if (cmsgp != NULL)
                return ((char *)cmsgp - (char *)msg.msg_control);
        else
                return (0);
#endif
}
#endif /* USE_CMSG */

/*
 * Process control messages received on a socket.
 */
static void
process_cmsg(isc__socket_t *sock, struct msghdr *msg, isc_socketevent_t *dev) {
#ifdef USE_CMSG
        struct cmsghdr *cmsgp;
#ifdef ISC_PLATFORM_HAVEIN6PKTINFO
        struct in6_pktinfo *pktinfop;
#endif
#ifdef SO_TIMESTAMP
        void *timevalp;
#endif
#endif

        /*
         * sock is used only when ISC_NET_BSD44MSGHDR and USE_CMSG are defined.
         * msg and dev are used only when ISC_NET_BSD44MSGHDR is defined.
         * They are all here, outside of the CPP tests, because it is
         * more consistent with the usual ISC coding style.
         */
        UNUSED(sock);
        UNUSED(msg);
        UNUSED(dev);

#ifdef ISC_NET_BSD44MSGHDR

#ifdef MSG_TRUNC
        if ((msg->msg_flags & MSG_TRUNC) == MSG_TRUNC)
                dev->attributes |= ISC_SOCKEVENTATTR_TRUNC;
#endif

#ifdef MSG_CTRUNC
        if ((msg->msg_flags & MSG_CTRUNC) == MSG_CTRUNC)
                dev->attributes |= ISC_SOCKEVENTATTR_CTRUNC;
#endif

#ifndef USE_CMSG
        return;
#else
        if (msg->msg_controllen == 0U || msg->msg_control == NULL)
                return;

#ifdef SO_TIMESTAMP
        timevalp = NULL;
#endif
#ifdef ISC_PLATFORM_HAVEIN6PKTINFO
        pktinfop = NULL;
#endif

        cmsgp = CMSG_FIRSTHDR(msg);
        while (cmsgp != NULL) {
                socket_log(sock, NULL, TRACE,
                           isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_PROCESSCMSG,
                           "processing cmsg %p", cmsgp);

#ifdef ISC_PLATFORM_HAVEIN6PKTINFO
                if (cmsgp->cmsg_level == IPPROTO_IPV6
                    && cmsgp->cmsg_type == IPV6_PKTINFO) {

                        pktinfop = (struct in6_pktinfo *)CMSG_DATA(cmsgp);
                        memmove(&dev->pktinfo, pktinfop,
                                sizeof(struct in6_pktinfo));
                        dev->attributes |= ISC_SOCKEVENTATTR_PKTINFO;
                        socket_log(sock, NULL, TRACE,
                                   isc_msgcat, ISC_MSGSET_SOCKET,
                                   ISC_MSG_IFRECEIVED,
                                   "interface received on ifindex %u",
                                   dev->pktinfo.ipi6_ifindex);
                        if (IN6_IS_ADDR_MULTICAST(&pktinfop->ipi6_addr))
                                dev->attributes |= ISC_SOCKEVENTATTR_MULTICAST;
                        goto next;
                }
#endif

#ifdef SO_TIMESTAMP
                if (cmsgp->cmsg_level == SOL_SOCKET
                    && cmsgp->cmsg_type == SCM_TIMESTAMP) {
                        struct timeval tv;
                        timevalp = CMSG_DATA(cmsgp);
                        memmove(&tv, timevalp, sizeof(tv));
                        dev->timestamp.seconds = tv.tv_sec;
                        dev->timestamp.nanoseconds = tv.tv_usec * 1000;
                        dev->attributes |= ISC_SOCKEVENTATTR_TIMESTAMP;
                        goto next;
                }
#endif

        next:
                cmsgp = CMSG_NXTHDR(msg, cmsgp);
        }
#endif /* USE_CMSG */

#endif /* ISC_NET_BSD44MSGHDR */
}

/*
 * Construct an iov array and attach it to the msghdr passed in.  This is
 * the SEND constructor, which will use the used region of the buffer
 * (if using a buffer list) or will use the internal region (if a single
 * buffer I/O is requested).
 *
 * Nothing can be NULL, and the done event must list at least one buffer
 * on the buffer linked list for this function to be meaningful.
 *
 * If write_countp != NULL, *write_countp will hold the number of bytes
 * this transaction can send.
 */
static void
build_msghdr_send(isc__socket_t *sock, isc_socketevent_t *dev,
                  struct msghdr *msg, struct iovec *iov, size_t *write_countp)
{
        unsigned int iovcount;
        isc_buffer_t *buffer;
        isc_region_t used;
        size_t write_count;
        size_t skip_count;

        memset(msg, 0, sizeof(*msg));

        if (!sock->connected) {
                msg->msg_name = (void *)&dev->address.type.sa;
                msg->msg_namelen = dev->address.length;
        } else {
                msg->msg_name = NULL;
                msg->msg_namelen = 0;
        }

        buffer = ISC_LIST_HEAD(dev->bufferlist);
        write_count = 0;
        iovcount = 0;

        /*
         * Single buffer I/O?  Skip what we've done so far in this region.
         */
        if (buffer == NULL) {
                write_count = dev->region.length - dev->n;
                iov[0].iov_base = (void *)(dev->region.base + dev->n);
                iov[0].iov_len = write_count;
                iovcount = 1;

                goto config;
        }

        /*
         * Multibuffer I/O.
         * Skip the data in the buffer list that we have already written.
         */
        skip_count = dev->n;
        while (buffer != NULL) {
                REQUIRE(ISC_BUFFER_VALID(buffer));
                if (skip_count < isc_buffer_usedlength(buffer))
                        break;
                skip_count -= isc_buffer_usedlength(buffer);
                buffer = ISC_LIST_NEXT(buffer, link);
        }

        while (buffer != NULL) {
                INSIST(iovcount < MAXSCATTERGATHER_SEND);

                isc_buffer_usedregion(buffer, &used);

                if (used.length > 0) {
                        iov[iovcount].iov_base = (void *)(used.base
                                                          + skip_count);
                        iov[iovcount].iov_len = used.length - skip_count;
                        write_count += (used.length - skip_count);
                        skip_count = 0;
                        iovcount++;
                }
                buffer = ISC_LIST_NEXT(buffer, link);
        }

        INSIST(skip_count == 0U);

 config:
        msg->msg_iov = iov;
        msg->msg_iovlen = iovcount;

#ifdef ISC_NET_BSD44MSGHDR
        msg->msg_control = NULL;
        msg->msg_controllen = 0;
        msg->msg_flags = 0;
#if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
        if ((sock->type == isc_sockettype_udp)
            && ((dev->attributes & ISC_SOCKEVENTATTR_PKTINFO) != 0)) {
#if defined(IPV6_USE_MIN_MTU)
                int use_min_mtu = 1;    /* -1, 0, 1 */
#endif
                struct cmsghdr *cmsgp;
                struct in6_pktinfo *pktinfop;

                socket_log(sock, NULL, TRACE,
                           isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_SENDTODATA,
                           "sendto pktinfo data, ifindex %u",
                           dev->pktinfo.ipi6_ifindex);

                msg->msg_controllen = cmsg_space(sizeof(struct in6_pktinfo));
                INSIST(msg->msg_controllen <= sock->sendcmsgbuflen);
                msg->msg_control = (void *)sock->sendcmsgbuf;

                cmsgp = (struct cmsghdr *)sock->sendcmsgbuf;
                cmsgp->cmsg_level = IPPROTO_IPV6;
                cmsgp->cmsg_type = IPV6_PKTINFO;
                cmsgp->cmsg_len = cmsg_len(sizeof(struct in6_pktinfo));
                pktinfop = (struct in6_pktinfo *)CMSG_DATA(cmsgp);
                memmove(pktinfop, &dev->pktinfo, sizeof(struct in6_pktinfo));
#if defined(IPV6_USE_MIN_MTU)
                /*
                 * Set IPV6_USE_MIN_MTU as a per packet option as FreeBSD
                 * ignores setsockopt(IPV6_USE_MIN_MTU) when IPV6_PKTINFO
                 * is used.
                 */
                cmsgp = (struct cmsghdr *)(sock->sendcmsgbuf +
                                           msg->msg_controllen);
                msg->msg_controllen += cmsg_space(sizeof(use_min_mtu));
                INSIST(msg->msg_controllen <= sock->sendcmsgbuflen);

                cmsgp->cmsg_level = IPPROTO_IPV6;
                cmsgp->cmsg_type = IPV6_USE_MIN_MTU;
                cmsgp->cmsg_len = cmsg_len(sizeof(use_min_mtu));
                memmove(CMSG_DATA(cmsgp), &use_min_mtu, sizeof(use_min_mtu));
#endif
        }
#endif /* USE_CMSG && ISC_PLATFORM_HAVEIPV6 */
#else /* ISC_NET_BSD44MSGHDR */
        msg->msg_accrights = NULL;
        msg->msg_accrightslen = 0;
#endif /* ISC_NET_BSD44MSGHDR */

        if (write_countp != NULL)
                *write_countp = write_count;
}

/*
 * Construct an iov array and attach it to the msghdr passed in.  This is
 * the RECV constructor, which will use the available region of the buffer
 * (if using a buffer list) or will use the internal region (if a single
 * buffer I/O is requested).
 *
 * Nothing can be NULL, and the done event must list at least one buffer
 * on the buffer linked list for this function to be meaningful.
 *
 * If read_countp != NULL, *read_countp will hold the number of bytes
 * this transaction can receive.
 */
static void
build_msghdr_recv(isc__socket_t *sock, isc_socketevent_t *dev,
                  struct msghdr *msg, struct iovec *iov, size_t *read_countp)
{
        unsigned int iovcount;
        isc_buffer_t *buffer;
        isc_region_t available;
        size_t read_count;

        memset(msg, 0, sizeof(struct msghdr));

        if (sock->type == isc_sockettype_udp) {
                memset(&dev->address, 0, sizeof(dev->address));
#ifdef BROKEN_RECVMSG
                if (sock->pf == AF_INET) {
                        msg->msg_name = (void *)&dev->address.type.sin;
                        msg->msg_namelen = sizeof(dev->address.type.sin6);
                } else if (sock->pf == AF_INET6) {
                        msg->msg_name = (void *)&dev->address.type.sin6;
                        msg->msg_namelen = sizeof(dev->address.type.sin6);
#ifdef ISC_PLATFORM_HAVESYSUNH
                } else if (sock->pf == AF_UNIX) {
                        msg->msg_name = (void *)&dev->address.type.sunix;
                        msg->msg_namelen = sizeof(dev->address.type.sunix);
#endif
                } else {
                        msg->msg_name = (void *)&dev->address.type.sa;
                        msg->msg_namelen = sizeof(dev->address.type);
                }
#else
                msg->msg_name = (void *)&dev->address.type.sa;
                msg->msg_namelen = sizeof(dev->address.type);
#endif
#ifdef ISC_NET_RECVOVERFLOW
                /* If needed, steal one iovec for overflow detection. */
                maxiov--;
#endif
        } else { /* TCP */
                msg->msg_name = NULL;
                msg->msg_namelen = 0;
                dev->address = sock->peer_address;
        }

        buffer = ISC_LIST_HEAD(dev->bufferlist);
        read_count = 0;

        /*
         * Single buffer I/O?  Skip what we've done so far in this region.
         */
        if (buffer == NULL) {
                read_count = dev->region.length - dev->n;
                iov[0].iov_base = (void *)(dev->region.base + dev->n);
                iov[0].iov_len = read_count;
                iovcount = 1;

                goto config;
        }

        /*
         * Multibuffer I/O.
         * Skip empty buffers.
         */
        while (buffer != NULL) {
                REQUIRE(ISC_BUFFER_VALID(buffer));
                if (isc_buffer_availablelength(buffer) != 0)
                        break;
                buffer = ISC_LIST_NEXT(buffer, link);
        }

        iovcount = 0;
        while (buffer != NULL) {
                INSIST(iovcount < MAXSCATTERGATHER_RECV);

                isc_buffer_availableregion(buffer, &available);

                if (available.length > 0) {
                        iov[iovcount].iov_base = (void *)(available.base);
                        iov[iovcount].iov_len = available.length;
                        read_count += available.length;
                        iovcount++;
                }
                buffer = ISC_LIST_NEXT(buffer, link);
        }

 config:

        /*
         * If needed, set up to receive that one extra byte.  Note that
         * we know there is at least one iov left, since we stole it
         * at the top of this function.
         */
#ifdef ISC_NET_RECVOVERFLOW
        if (sock->type == isc_sockettype_udp) {
                iov[iovcount].iov_base = (void *)(&sock->overflow);
                iov[iovcount].iov_len = 1;
                iovcount++;
        }
#endif

        msg->msg_iov = iov;
        msg->msg_iovlen = iovcount;

#ifdef ISC_NET_BSD44MSGHDR
#if defined(USE_CMSG)
        if (sock->type == isc_sockettype_udp) {
                msg->msg_control = sock->recvcmsgbuf;
                msg->msg_controllen = sock->recvcmsgbuflen;
        } else {
                msg->msg_control = NULL;
                msg->msg_controllen = 0;
        }
#else
        msg->msg_control = NULL;
        msg->msg_controllen = 0;
#endif /* USE_CMSG */
        msg->msg_flags = 0;
#else /* ISC_NET_BSD44MSGHDR */
        msg->msg_accrights = NULL;
        msg->msg_accrightslen = 0;
#endif /* ISC_NET_BSD44MSGHDR */

        if (read_countp != NULL)
                *read_countp = read_count;
}

static void
set_dev_address(isc_sockaddr_t *address, isc__socket_t *sock,
                isc_socketevent_t *dev)
{
        if (sock->type == isc_sockettype_udp) {
                if (address != NULL)
                        dev->address = *address;
                else
                        dev->address = sock->peer_address;
        } else if (sock->type == isc_sockettype_tcp) {
                INSIST(address == NULL);
                dev->address = sock->peer_address;
        }
}

static void
destroy_socketevent(isc_event_t *event) {
        isc_socketevent_t *ev = (isc_socketevent_t *)event;

        INSIST(ISC_LIST_EMPTY(ev->bufferlist));

        (ev->destroy)(event);
}

static isc_socketevent_t *
allocate_socketevent(isc__socket_t *sock, isc_eventtype_t eventtype,
                     isc_taskaction_t action, void *arg)
{
        isc_socketevent_t *ev;

        ev = (isc_socketevent_t *)isc_event_allocate(sock->manager->mctx,
                                                     sock, eventtype,
                                                     action, arg,
                                                     sizeof(*ev));

        if (ev == NULL)
                return (NULL);

        ev->result = ISC_R_UNSET;
        ISC_LINK_INIT(ev, ev_link);
        ISC_LIST_INIT(ev->bufferlist);
        ev->region.base = NULL;
        ev->n = 0;
        ev->offset = 0;
        ev->attributes = 0;
        ev->destroy = ev->ev_destroy;
        ev->ev_destroy = destroy_socketevent;

        return (ev);
}

#if defined(ISC_SOCKET_DEBUG)
static void
dump_msg(struct msghdr *msg) {
        unsigned int i;

        printf("MSGHDR %p\n", msg);
        printf("\tname %p, namelen %ld\n", msg->msg_name,
               (long) msg->msg_namelen);
        printf("\tiov %p, iovlen %ld\n", msg->msg_iov,
               (long) msg->msg_iovlen);
        for (i = 0; i < (unsigned int)msg->msg_iovlen; i++)
                printf("\t\t%d\tbase %p, len %ld\n", i,
                       msg->msg_iov[i].iov_base,
                       (long) msg->msg_iov[i].iov_len);
#ifdef ISC_NET_BSD44MSGHDR
        printf("\tcontrol %p, controllen %ld\n", msg->msg_control,
               (long) msg->msg_controllen);
#endif
}
#endif

#define DOIO_SUCCESS            0       /* i/o ok, event sent */
#define DOIO_SOFT               1       /* i/o ok, soft error, no event sent */
#define DOIO_HARD               2       /* i/o error, event sent */
#define DOIO_EOF                3       /* EOF, no event sent */

static int
doio_recv(isc__socket_t *sock, isc_socketevent_t *dev) {
        int cc;
        struct iovec iov[MAXSCATTERGATHER_RECV];
        size_t read_count;
        size_t actual_count;
        struct msghdr msghdr;
        isc_buffer_t *buffer;
        int recv_errno;
        char strbuf[ISC_STRERRORSIZE];

        build_msghdr_recv(sock, dev, &msghdr, iov, &read_count);

#if defined(ISC_SOCKET_DEBUG)
        dump_msg(&msghdr);
#endif

        cc = recvmsg(sock->fd, &msghdr, 0);
        recv_errno = errno;

#if defined(ISC_SOCKET_DEBUG)
        dump_msg(&msghdr);
#endif

        if (cc < 0) {
                if (SOFT_ERROR(recv_errno))
                        return (DOIO_SOFT);

                if (isc_log_wouldlog(isc_lctx, IOEVENT_LEVEL)) {
                        isc__strerror(recv_errno, strbuf, sizeof(strbuf));
                        socket_log(sock, NULL, IOEVENT,
                                   isc_msgcat, ISC_MSGSET_SOCKET,
                                   ISC_MSG_DOIORECV,
                                  "doio_recv: recvmsg(%d) %d bytes, err %d/%s",
                                   sock->fd, cc, recv_errno, strbuf);
                }

#define SOFT_OR_HARD(_system, _isc) \
        if (recv_errno == _system) { \
                if (sock->connected) { \
                        dev->result = _isc; \
                        inc_stats(sock->manager->stats, \
                                  sock->statsindex[STATID_RECVFAIL]); \
                        return (DOIO_HARD); \
                } \
                return (DOIO_SOFT); \
        }
#define ALWAYS_HARD(_system, _isc) \
        if (recv_errno == _system) { \
                dev->result = _isc; \
                inc_stats(sock->manager->stats, \
                          sock->statsindex[STATID_RECVFAIL]); \
                return (DOIO_HARD); \
        }

                SOFT_OR_HARD(ECONNREFUSED, ISC_R_CONNREFUSED);
                SOFT_OR_HARD(ENETUNREACH, ISC_R_NETUNREACH);
                SOFT_OR_HARD(EHOSTUNREACH, ISC_R_HOSTUNREACH);
                SOFT_OR_HARD(EHOSTDOWN, ISC_R_HOSTDOWN);
                /* HPUX 11.11 can return EADDRNOTAVAIL. */
                SOFT_OR_HARD(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
                ALWAYS_HARD(ENOBUFS, ISC_R_NORESOURCES);
                /* Should never get this one but it was seen. */
#ifdef ENOPROTOOPT
                SOFT_OR_HARD(ENOPROTOOPT, ISC_R_HOSTUNREACH);
#endif
                /*
                 * HPUX returns EPROTO and EINVAL on receiving some ICMP/ICMPv6
                 * errors.
                 */
#ifdef EPROTO
                SOFT_OR_HARD(EPROTO, ISC_R_HOSTUNREACH);
#endif
                SOFT_OR_HARD(EINVAL, ISC_R_HOSTUNREACH);

#undef SOFT_OR_HARD
#undef ALWAYS_HARD

                dev->result = isc__errno2result(recv_errno);
                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_RECVFAIL]);
                return (DOIO_HARD);
        }

        /*
         * On TCP and UNIX sockets, zero length reads indicate EOF,
         * while on UDP sockets, zero length reads are perfectly valid,
         * although strange.
         */
        switch (sock->type) {
        case isc_sockettype_tcp:
        case isc_sockettype_unix:
                if (cc == 0)
                        return (DOIO_EOF);
                break;
        case isc_sockettype_udp:
                break;
        case isc_sockettype_fdwatch:
        default:
                INSIST(0);
        }

        if (sock->type == isc_sockettype_udp) {
                dev->address.length = msghdr.msg_namelen;
                if (isc_sockaddr_getport(&dev->address) == 0) {
                        if (isc_log_wouldlog(isc_lctx, IOEVENT_LEVEL)) {
                                socket_log(sock, &dev->address, IOEVENT,
                                           isc_msgcat, ISC_MSGSET_SOCKET,
                                           ISC_MSG_ZEROPORT,
                                           "dropping source port zero packet");
                        }
                        return (DOIO_SOFT);
                }
                /*
                 * Simulate a firewall blocking UDP responses bigger than
                 * 'maxudp' bytes.
                 */
                if (sock->manager->maxudp != 0 && cc > sock->manager->maxudp)
                        return (DOIO_SOFT);
        }

        socket_log(sock, &dev->address, IOEVENT,
                   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_PKTRECV,
                   "packet received correctly");

        /*
         * Overflow bit detection.  If we received MORE bytes than we should,
         * this indicates an overflow situation.  Set the flag in the
         * dev entry and adjust how much we read by one.
         */
#ifdef ISC_NET_RECVOVERFLOW
        if ((sock->type == isc_sockettype_udp) && ((size_t)cc > read_count)) {
                dev->attributes |= ISC_SOCKEVENTATTR_TRUNC;
                cc--;
        }
#endif

        /*
         * If there are control messages attached, run through them and pull
         * out the interesting bits.
         */
        if (sock->type == isc_sockettype_udp)
                process_cmsg(sock, &msghdr, dev);

        /*
         * update the buffers (if any) and the i/o count
         */
        dev->n += cc;
        actual_count = cc;
        buffer = ISC_LIST_HEAD(dev->bufferlist);
        while (buffer != NULL && actual_count > 0U) {
                REQUIRE(ISC_BUFFER_VALID(buffer));
                if (isc_buffer_availablelength(buffer) <= actual_count) {
                        actual_count -= isc_buffer_availablelength(buffer);
                        isc_buffer_add(buffer,
                                       isc_buffer_availablelength(buffer));
                } else {
                        isc_buffer_add(buffer, actual_count);
                        actual_count = 0;
                        POST(actual_count);
                        break;
                }
                buffer = ISC_LIST_NEXT(buffer, link);
                if (buffer == NULL) {
                        INSIST(actual_count == 0U);
                }
        }

        /*
         * If we read less than we expected, update counters,
         * and let the upper layer poke the descriptor.
         */
        if (((size_t)cc != read_count) && (dev->n < dev->minimum))
                return (DOIO_SOFT);

        /*
         * Full reads are posted, or partials if partials are ok.
         */
        dev->result = ISC_R_SUCCESS;
        return (DOIO_SUCCESS);
}

/*
 * Returns:
 *      DOIO_SUCCESS    The operation succeeded.  dev->result contains
 *                      ISC_R_SUCCESS.
 *
 *      DOIO_HARD       A hard or unexpected I/O error was encountered.
 *                      dev->result contains the appropriate error.
 *
 *      DOIO_SOFT       A soft I/O error was encountered.  No senddone
 *                      event was sent.  The operation should be retried.
 *
 *      No other return values are possible.
 */
static int
doio_send(isc__socket_t *sock, isc_socketevent_t *dev) {
        int cc;
        struct iovec iov[MAXSCATTERGATHER_SEND];
        size_t write_count;
        struct msghdr msghdr;
        char addrbuf[ISC_SOCKADDR_FORMATSIZE];
        int attempts = 0;
        int send_errno;
        char strbuf[ISC_STRERRORSIZE];

        build_msghdr_send(sock, dev, &msghdr, iov, &write_count);

 resend:
        if (sock->type == isc_sockettype_udp &&
            sock->manager->maxudp != 0 &&
            write_count > (size_t)sock->manager->maxudp)
                cc = write_count;
        else
                cc = sendmsg(sock->fd, &msghdr, 0);
        send_errno = errno;

        /*
         * Check for error or block condition.
         */
        if (cc < 0) {
                if (send_errno == EINTR && ++attempts < NRETRIES)
                        goto resend;

                if (SOFT_ERROR(send_errno)) {
                        if (errno == EWOULDBLOCK || errno == EAGAIN)
                                dev->result = ISC_R_WOULDBLOCK;
                        return (DOIO_SOFT);
                }

#define SOFT_OR_HARD(_system, _isc) \
        if (send_errno == _system) { \
                if (sock->connected) { \
                        dev->result = _isc; \
                        inc_stats(sock->manager->stats, \
                                  sock->statsindex[STATID_SENDFAIL]); \
                        return (DOIO_HARD); \
                } \
                return (DOIO_SOFT); \
        }
#define ALWAYS_HARD(_system, _isc) \
        if (send_errno == _system) { \
                dev->result = _isc; \
                inc_stats(sock->manager->stats, \
                          sock->statsindex[STATID_SENDFAIL]); \
                return (DOIO_HARD); \
        }

                SOFT_OR_HARD(ECONNREFUSED, ISC_R_CONNREFUSED);
                ALWAYS_HARD(EACCES, ISC_R_NOPERM);
                ALWAYS_HARD(EAFNOSUPPORT, ISC_R_ADDRNOTAVAIL);
                ALWAYS_HARD(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
                ALWAYS_HARD(EHOSTUNREACH, ISC_R_HOSTUNREACH);
#ifdef EHOSTDOWN
                ALWAYS_HARD(EHOSTDOWN, ISC_R_HOSTUNREACH);
#endif
                ALWAYS_HARD(ENETUNREACH, ISC_R_NETUNREACH);
                ALWAYS_HARD(ENOBUFS, ISC_R_NORESOURCES);
                ALWAYS_HARD(EPERM, ISC_R_HOSTUNREACH);
                ALWAYS_HARD(EPIPE, ISC_R_NOTCONNECTED);
                ALWAYS_HARD(ECONNRESET, ISC_R_CONNECTIONRESET);

#undef SOFT_OR_HARD
#undef ALWAYS_HARD

                /*
                 * The other error types depend on whether or not the
                 * socket is UDP or TCP.  If it is UDP, some errors
                 * that we expect to be fatal under TCP are merely
                 * annoying, and are really soft errors.
                 *
                 * However, these soft errors are still returned as
                 * a status.
                 */
                isc_sockaddr_format(&dev->address, addrbuf, sizeof(addrbuf));
                isc__strerror(send_errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__, "internal_send: %s: %s",
                                 addrbuf, strbuf);
                dev->result = isc__errno2result(send_errno);
                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_SENDFAIL]);
                return (DOIO_HARD);
        }

        if (cc == 0) {
                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_SENDFAIL]);
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "doio_send: send() %s 0",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_RETURNED, "returned"));
        }

        /*
         * If we write less than we expected, update counters, poke.
         */
        dev->n += cc;
        if ((size_t)cc != write_count)
                return (DOIO_SOFT);

        /*
         * Exactly what we wanted to write.  We're done with this
         * entry.  Post its completion event.
         */
        dev->result = ISC_R_SUCCESS;
        return (DOIO_SUCCESS);
}

/*
 * Kill.
 *
 * Caller must ensure that the socket is not locked and no external
 * references exist.
 */
static void
socketclose(isc__socketmgr_t *manager, isc__socket_t *sock, int fd) {
        isc_sockettype_t type = sock->type;
        int lockid = FDLOCK_ID(fd);

        /*
         * No one has this socket open, so the watcher doesn't have to be
         * poked, and the socket doesn't have to be locked.
         */
        LOCK(&manager->fdlock[lockid]);
        manager->fds[fd] = NULL;
        if (type == isc_sockettype_fdwatch)
                manager->fdstate[fd] = CLOSED;
        else
                manager->fdstate[fd] = CLOSE_PENDING;
        UNLOCK(&manager->fdlock[lockid]);
        if (type == isc_sockettype_fdwatch) {
                /*
                 * The caller may close the socket once this function returns,
                 * and `fd' may be reassigned for a new socket.  So we do
                 * unwatch_fd() here, rather than defer it via select_poke().
                 * Note: this may complicate data protection among threads and
                 * may reduce performance due to additional locks.  One way to
                 * solve this would be to dup() the watched descriptor, but we
                 * take a simpler approach at this moment.
                 */
                (void)unwatch_fd(manager, fd, SELECT_POKE_READ);
                (void)unwatch_fd(manager, fd, SELECT_POKE_WRITE);
        } else
                select_poke(manager, fd, SELECT_POKE_CLOSE);

        inc_stats(manager->stats, sock->statsindex[STATID_CLOSE]);

        /*
         * update manager->maxfd here (XXX: this should be implemented more
         * efficiently)
         */
#ifdef USE_SELECT
        LOCK(&manager->lock);
        if (manager->maxfd == fd) {
                int i;

                manager->maxfd = 0;
                for (i = fd - 1; i >= 0; i--) {
                        lockid = FDLOCK_ID(i);

                        LOCK(&manager->fdlock[lockid]);
                        if (manager->fdstate[i] == MANAGED) {
                                manager->maxfd = i;
                                UNLOCK(&manager->fdlock[lockid]);
                                break;
                        }
                        UNLOCK(&manager->fdlock[lockid]);
                }
#ifdef ISC_PLATFORM_USETHREADS
                if (manager->maxfd < manager->pipe_fds[0])
                        manager->maxfd = manager->pipe_fds[0];
#endif
        }
        UNLOCK(&manager->lock);
#endif  /* USE_SELECT */
}

static void
destroy(isc__socket_t **sockp) {
        int fd;
        isc__socket_t *sock = *sockp;
        isc__socketmgr_t *manager = sock->manager;

        socket_log(sock, NULL, CREATION, isc_msgcat, ISC_MSGSET_SOCKET,
                   ISC_MSG_DESTROYING, "destroying");

        INSIST(ISC_LIST_EMPTY(sock->accept_list));
        INSIST(ISC_LIST_EMPTY(sock->recv_list));
        INSIST(ISC_LIST_EMPTY(sock->send_list));
        INSIST(sock->connect_ev == NULL);
        INSIST(sock->fd >= -1 && sock->fd < (int)manager->maxsocks);

        if (sock->fd >= 0) {
                fd = sock->fd;
                sock->fd = -1;
                socketclose(manager, sock, fd);
        }

        LOCK(&manager->lock);

        ISC_LIST_UNLINK(manager->socklist, sock, link);

#ifdef USE_WATCHER_THREAD
        if (ISC_LIST_EMPTY(manager->socklist))
                SIGNAL(&manager->shutdown_ok);
#endif /* USE_WATCHER_THREAD */

        /* can't unlock manager as its memory context is still used */
        free_socket(sockp);

        UNLOCK(&manager->lock);
}

static isc_result_t
allocate_socket(isc__socketmgr_t *manager, isc_sockettype_t type,
                isc__socket_t **socketp)
{
        isc__socket_t *sock;
        isc_result_t result;
        ISC_SOCKADDR_LEN_T cmsgbuflen;

        sock = isc_mem_get(manager->mctx, sizeof(*sock));

        if (sock == NULL)
                return (ISC_R_NOMEMORY);

        sock->common.magic = 0;
        sock->common.impmagic = 0;
        sock->references = 0;

        sock->manager = manager;
        sock->type = type;
        sock->fd = -1;
        sock->dupped = 0;
        sock->statsindex = NULL;

        ISC_LINK_INIT(sock, link);

        sock->recvcmsgbuf = NULL;
        sock->sendcmsgbuf = NULL;

        /*
         * Set up cmsg buffers.
         */
        cmsgbuflen = 0;
#if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
        cmsgbuflen += cmsg_space(sizeof(struct in6_pktinfo));
#endif
#if defined(USE_CMSG) && defined(SO_TIMESTAMP)
        cmsgbuflen += cmsg_space(sizeof(struct timeval));
#endif
        sock->recvcmsgbuflen = cmsgbuflen;
        if (sock->recvcmsgbuflen != 0U) {
                sock->recvcmsgbuf = isc_mem_get(manager->mctx, cmsgbuflen);
                if (sock->recvcmsgbuf == NULL) {
                        result = ISC_R_NOMEMORY;
                        goto error;
                }
        }

        cmsgbuflen = 0;
#if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
        cmsgbuflen += cmsg_space(sizeof(struct in6_pktinfo));
#if defined(IPV6_USE_MIN_MTU)
        /*
         * Provide space for working around FreeBSD's broken IPV6_USE_MIN_MTU
         * support.
         */
        cmsgbuflen += cmsg_space(sizeof(int));
#endif
#endif
        sock->sendcmsgbuflen = cmsgbuflen;
        if (sock->sendcmsgbuflen != 0U) {
                sock->sendcmsgbuf = isc_mem_get(manager->mctx, cmsgbuflen);
                if (sock->sendcmsgbuf == NULL) {
                        result = ISC_R_NOMEMORY;
                        goto error;
                }
        }

        memset(sock->name, 0, sizeof(sock->name));
        sock->tag = NULL;

        /*
         * Set up list of readers and writers to be initially empty.
         */
        ISC_LIST_INIT(sock->recv_list);
        ISC_LIST_INIT(sock->send_list);
        ISC_LIST_INIT(sock->accept_list);
        sock->connect_ev = NULL;
        sock->pending_recv = 0;
        sock->pending_send = 0;
        sock->pending_accept = 0;
        sock->listener = 0;
        sock->connected = 0;
        sock->connecting = 0;
        sock->bound = 0;

        /*
         * Initialize the lock.
         */
        result = isc_mutex_init(&sock->lock);
        if (result != ISC_R_SUCCESS) {
                sock->common.magic = 0;
                sock->common.impmagic = 0;
                goto error;
        }

        /*
         * Initialize readable and writable events.
         */
        ISC_EVENT_INIT(&sock->readable_ev, sizeof(intev_t),
                       ISC_EVENTATTR_NOPURGE, NULL, ISC_SOCKEVENT_INTR,
                       NULL, sock, sock, NULL, NULL);
        ISC_EVENT_INIT(&sock->writable_ev, sizeof(intev_t),
                       ISC_EVENTATTR_NOPURGE, NULL, ISC_SOCKEVENT_INTW,
                       NULL, sock, sock, NULL, NULL);

        sock->common.magic = ISCAPI_SOCKET_MAGIC;
        sock->common.impmagic = SOCKET_MAGIC;
        *socketp = sock;

        return (ISC_R_SUCCESS);

 error:
        if (sock->recvcmsgbuf != NULL)
                isc_mem_put(manager->mctx, sock->recvcmsgbuf,
                            sock->recvcmsgbuflen);
        if (sock->sendcmsgbuf != NULL)
                isc_mem_put(manager->mctx, sock->sendcmsgbuf,
                            sock->sendcmsgbuflen);
        isc_mem_put(manager->mctx, sock, sizeof(*sock));

        return (result);
}

/*
 * This event requires that the various lists be empty, that the reference
 * count be 1, and that the magic number is valid.  The other socket bits,
 * like the lock, must be initialized as well.  The fd associated must be
 * marked as closed, by setting it to -1 on close, or this routine will
 * also close the socket.
 */
static void
free_socket(isc__socket_t **socketp) {
        isc__socket_t *sock = *socketp;

        INSIST(VALID_SOCKET(sock));
        INSIST(sock->references == 0);
        INSIST(!sock->connecting);
        INSIST(!sock->pending_recv);
        INSIST(!sock->pending_send);
        INSIST(!sock->pending_accept);
        INSIST(ISC_LIST_EMPTY(sock->recv_list));
        INSIST(ISC_LIST_EMPTY(sock->send_list));
        INSIST(ISC_LIST_EMPTY(sock->accept_list));
        INSIST(!ISC_LINK_LINKED(sock, link));

        if (sock->recvcmsgbuf != NULL)
                isc_mem_put(sock->manager->mctx, sock->recvcmsgbuf,
                            sock->recvcmsgbuflen);
        if (sock->sendcmsgbuf != NULL)
                isc_mem_put(sock->manager->mctx, sock->sendcmsgbuf,
                            sock->sendcmsgbuflen);

        sock->common.magic = 0;
        sock->common.impmagic = 0;

        DESTROYLOCK(&sock->lock);

        isc_mem_put(sock->manager->mctx, sock, sizeof(*sock));

        *socketp = NULL;
}

#ifdef SO_BSDCOMPAT
/*
 * This really should not be necessary to do.  Having to workout
 * which kernel version we are on at run time so that we don't cause
 * the kernel to issue a warning about us using a deprecated socket option.
 * Such warnings should *never* be on by default in production kernels.
 *
 * We can't do this a build time because executables are moved between
 * machines and hence kernels.
 *
 * We can't just not set SO_BSDCOMAT because some kernels require it.
 */

static isc_once_t         bsdcompat_once = ISC_ONCE_INIT;
isc_boolean_t bsdcompat = ISC_TRUE;

static void
clear_bsdcompat(void) {
#ifdef __linux__
         struct utsname buf;
         char *endp;
         long int major;
         long int minor;

         uname(&buf);    /* Can only fail if buf is bad in Linux. */

         /* Paranoia in parsing can be increased, but we trust uname(). */
         major = strtol(buf.release, &endp, 10);
         if (*endp == '.') {
                minor = strtol(endp+1, &endp, 10);
                if ((major > 2) || ((major == 2) && (minor >= 4))) {
                        bsdcompat = ISC_FALSE;
                }
         }
#endif /* __linux __ */
}
#endif

static void
use_min_mtu(isc__socket_t *sock) {
#if !defined(IPV6_USE_MIN_MTU) && !defined(IPV6_MTU)
        UNUSED(sock);
#endif
#ifdef IPV6_USE_MIN_MTU
        /* use minimum MTU */
        if (sock->pf == AF_INET6) {
                int on = 1;
                (void)setsockopt(sock->fd, IPPROTO_IPV6, IPV6_USE_MIN_MTU,
                                (void *)&on, sizeof(on));
        }
#endif
#if defined(IPV6_MTU)
        /*
         * Use minimum MTU on IPv6 sockets.
         */
        if (sock->pf == AF_INET6) {
                int mtu = 1280;
                (void)setsockopt(sock->fd, IPPROTO_IPV6, IPV6_MTU,
                                 &mtu, sizeof(mtu));
        }
#endif
}

static isc_result_t
opensocket(isc__socketmgr_t *manager, isc__socket_t *sock,
           isc__socket_t *dup_socket)
{
        isc_result_t result;
        char strbuf[ISC_STRERRORSIZE];
        const char *err = "socket";
        int tries = 0;
#if defined(USE_CMSG) || defined(SO_BSDCOMPAT) || defined(SO_NOSIGPIPE)
        int on = 1;
#endif
#if defined(SO_RCVBUF)
        ISC_SOCKADDR_LEN_T optlen;
        int size;
#endif

 again:
        if (dup_socket == NULL) {
                switch (sock->type) {
                case isc_sockettype_udp:
                        sock->fd = socket(sock->pf, SOCK_DGRAM, IPPROTO_UDP);
                        break;
                case isc_sockettype_tcp:
                        sock->fd = socket(sock->pf, SOCK_STREAM, IPPROTO_TCP);
                        break;
                case isc_sockettype_unix:
                        sock->fd = socket(sock->pf, SOCK_STREAM, 0);
                        break;
                case isc_sockettype_fdwatch:
                        /*
                         * We should not be called for isc_sockettype_fdwatch
                         * sockets.
                         */
                        INSIST(0);
                        break;
                }
        } else {
                sock->fd = dup(dup_socket->fd);
                sock->dupped = 1;
                sock->bound = dup_socket->bound;
        }
        if (sock->fd == -1 && errno == EINTR && tries++ < 42)
                goto again;

#ifdef F_DUPFD
        /*
         * Leave a space for stdio and TCP to work in.
         */
        if (manager->reserved != 0 && sock->type == isc_sockettype_udp &&
            sock->fd >= 0 && sock->fd < manager->reserved) {
                int new, tmp;
                new = fcntl(sock->fd, F_DUPFD, manager->reserved);
                tmp = errno;
                (void)close(sock->fd);
                errno = tmp;
                sock->fd = new;
                err = "isc_socket_create: fcntl/reserved";
        } else if (sock->fd >= 0 && sock->fd < 20) {
                int new, tmp;
                new = fcntl(sock->fd, F_DUPFD, 20);
                tmp = errno;
                (void)close(sock->fd);
                errno = tmp;
                sock->fd = new;
                err = "isc_socket_create: fcntl";
        }
#endif

        if (sock->fd >= (int)manager->maxsocks) {
                (void)close(sock->fd);
                isc_log_iwrite(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                               ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                               isc_msgcat, ISC_MSGSET_SOCKET,
                               ISC_MSG_TOOMANYFDS,
                               "socket: file descriptor exceeds limit (%d/%u)",
                               sock->fd, manager->maxsocks);
                return (ISC_R_NORESOURCES);
        }

        if (sock->fd < 0) {
                switch (errno) {
                case EMFILE:
                case ENFILE:
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        isc_log_iwrite(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                       ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                                       isc_msgcat, ISC_MSGSET_SOCKET,
                                       ISC_MSG_TOOMANYFDS,
                                       "%s: %s", err, strbuf);
                        /* fallthrough */
                case ENOBUFS:
                        return (ISC_R_NORESOURCES);

                case EPROTONOSUPPORT:
                case EPFNOSUPPORT:
                case EAFNOSUPPORT:
                /*
                 * Linux 2.2 (and maybe others) return EINVAL instead of
                 * EAFNOSUPPORT.
                 */
                case EINVAL:
                        return (ISC_R_FAMILYNOSUPPORT);

                default:
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "%s() %s: %s", err,
                                         isc_msgcat_get(isc_msgcat,
                                                        ISC_MSGSET_GENERAL,
                                                        ISC_MSG_FAILED,
                                                        "failed"),
                                         strbuf);
                        return (ISC_R_UNEXPECTED);
                }
        }

        if (dup_socket != NULL)
                goto setup_done;

        result = make_nonblock(sock->fd);
        if (result != ISC_R_SUCCESS) {
                (void)close(sock->fd);
                return (result);
        }

#ifdef SO_BSDCOMPAT
        RUNTIME_CHECK(isc_once_do(&bsdcompat_once,
                                  clear_bsdcompat) == ISC_R_SUCCESS);
        if (sock->type != isc_sockettype_unix && bsdcompat &&
            setsockopt(sock->fd, SOL_SOCKET, SO_BSDCOMPAT,
                       (void *)&on, sizeof(on)) < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "setsockopt(%d, SO_BSDCOMPAT) %s: %s",
                                 sock->fd,
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"),
                                 strbuf);
                /* Press on... */
        }
#endif

#ifdef SO_NOSIGPIPE
        if (setsockopt(sock->fd, SOL_SOCKET, SO_NOSIGPIPE,
                       (void *)&on, sizeof(on)) < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "setsockopt(%d, SO_NOSIGPIPE) %s: %s",
                                 sock->fd,
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"),
                                 strbuf);
                /* Press on... */
        }
#endif

        /*
         * Use minimum mtu if possible.
         */
        use_min_mtu(sock);

#if defined(USE_CMSG) || defined(SO_RCVBUF)
        if (sock->type == isc_sockettype_udp) {

#if defined(USE_CMSG)
#if defined(SO_TIMESTAMP)
                if (setsockopt(sock->fd, SOL_SOCKET, SO_TIMESTAMP,
                               (void *)&on, sizeof(on)) < 0
                    && errno != ENOPROTOOPT) {
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "setsockopt(%d, SO_TIMESTAMP) %s: %s",
                                         sock->fd,
                                         isc_msgcat_get(isc_msgcat,
                                                        ISC_MSGSET_GENERAL,
                                                        ISC_MSG_FAILED,
                                                        "failed"),
                                         strbuf);
                        /* Press on... */
                }
#endif /* SO_TIMESTAMP */

#if defined(ISC_PLATFORM_HAVEIPV6)
                if (sock->pf == AF_INET6 && sock->recvcmsgbuflen == 0U) {
                        /*
                         * Warn explicitly because this anomaly can be hidden
                         * in usual operation (and unexpectedly appear later).
                         */
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "No buffer available to receive "
                                         "IPv6 destination");
                }
#ifdef ISC_PLATFORM_HAVEIN6PKTINFO
#ifdef IPV6_RECVPKTINFO
                /* RFC 3542 */
                if ((sock->pf == AF_INET6)
                    && (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
                                   (void *)&on, sizeof(on)) < 0)) {
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "setsockopt(%d, IPV6_RECVPKTINFO) "
                                         "%s: %s", sock->fd,
                                         isc_msgcat_get(isc_msgcat,
                                                        ISC_MSGSET_GENERAL,
                                                        ISC_MSG_FAILED,
                                                        "failed"),
                                         strbuf);
                }
#else
                /* RFC 2292 */
                if ((sock->pf == AF_INET6)
                    && (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_PKTINFO,
                                   (void *)&on, sizeof(on)) < 0)) {
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "setsockopt(%d, IPV6_PKTINFO) %s: %s",
                                         sock->fd,
                                         isc_msgcat_get(isc_msgcat,
                                                        ISC_MSGSET_GENERAL,
                                                        ISC_MSG_FAILED,
                                                        "failed"),
                                         strbuf);
                }
#endif /* IPV6_RECVPKTINFO */
#endif /* ISC_PLATFORM_HAVEIN6PKTINFO */
#if defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DONT)
                /*
                 * Turn off Path MTU discovery on IPv6/UDP sockets.
                 */
                if (sock->pf == AF_INET6) {
                        int action = IPV6_PMTUDISC_DONT;
                        (void)setsockopt(sock->fd, IPPROTO_IPV6,
                                         IPV6_MTU_DISCOVER, &action,
                                         sizeof(action));
                }
#endif
#endif /* ISC_PLATFORM_HAVEIPV6 */
#endif /* defined(USE_CMSG) */

#if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
                /*
                 * Turn off Path MTU discovery on IPv4/UDP sockets.
                 */
                if (sock->pf == AF_INET) {
                        int action = IP_PMTUDISC_DONT;
                        (void)setsockopt(sock->fd, IPPROTO_IP, IP_MTU_DISCOVER,
                                         &action, sizeof(action));
                }
#endif
#if defined(IP_DONTFRAG)
                /*
                 * Turn off Path MTU discovery on IPv4/UDP sockets.
                 */
                if (sock->pf == AF_INET) {
                        int off = 0;
                        (void)setsockopt(sock->fd, IPPROTO_IP, IP_DONTFRAG,
                                         &off, sizeof(off));
                }
#endif

#if defined(SO_RCVBUF)
                optlen = sizeof(size);
                if (getsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF,
                               (void *)&size, &optlen) >= 0 &&
                     size < RCVBUFSIZE) {
                        size = RCVBUFSIZE;
                        if (setsockopt(sock->fd, SOL_SOCKET, SO_RCVBUF,
                                       (void *)&size, sizeof(size)) == -1) {
                                isc__strerror(errno, strbuf, sizeof(strbuf));
                                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                        "setsockopt(%d, SO_RCVBUF, %d) %s: %s",
                                        sock->fd, size,
                                        isc_msgcat_get(isc_msgcat,
                                                       ISC_MSGSET_GENERAL,
                                                       ISC_MSG_FAILED,
                                                       "failed"),
                                        strbuf);
                        }
                }
#endif
        }
#endif /* defined(USE_CMSG) || defined(SO_RCVBUF) */

setup_done:
        inc_stats(manager->stats, sock->statsindex[STATID_OPEN]);

        return (ISC_R_SUCCESS);
}

/*
 * Create a 'type' socket or duplicate an existing socket, managed
 * by 'manager'.  Events will be posted to 'task' and when dispatched
 * 'action' will be called with 'arg' as the arg value.  The new
 * socket is returned in 'socketp'.
 */
static isc_result_t
socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
              isc_socket_t **socketp, isc_socket_t *dup_socket)
{
        isc__socket_t *sock = NULL;
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;
        isc_result_t result;
        int lockid;

        REQUIRE(VALID_MANAGER(manager));
        REQUIRE(socketp != NULL && *socketp == NULL);
        REQUIRE(type != isc_sockettype_fdwatch);

        result = allocate_socket(manager, type, &sock);
        if (result != ISC_R_SUCCESS)
                return (result);

        switch (sock->type) {
        case isc_sockettype_udp:
                sock->statsindex =
                        (pf == AF_INET) ? udp4statsindex : udp6statsindex;
                break;
        case isc_sockettype_tcp:
                sock->statsindex =
                        (pf == AF_INET) ? tcp4statsindex : tcp6statsindex;
                break;
        case isc_sockettype_unix:
                sock->statsindex = unixstatsindex;
                break;
        default:
                INSIST(0);
        }

        sock->pf = pf;

        result = opensocket(manager, sock, (isc__socket_t *)dup_socket);
        if (result != ISC_R_SUCCESS) {
                inc_stats(manager->stats, sock->statsindex[STATID_OPENFAIL]);
                free_socket(&sock);
                return (result);
        }

        sock->common.methods = (isc_socketmethods_t *)&socketmethods;
        sock->references = 1;
        *socketp = (isc_socket_t *)sock;

        /*
         * Note we don't have to lock the socket like we normally would because
         * there are no external references to it yet.
         */

        lockid = FDLOCK_ID(sock->fd);
        LOCK(&manager->fdlock[lockid]);
        manager->fds[sock->fd] = sock;
        manager->fdstate[sock->fd] = MANAGED;
#if defined(USE_EPOLL)
        manager->epoll_events[sock->fd] = 0;
#endif
#ifdef USE_DEVPOLL
        INSIST(sock->manager->fdpollinfo[sock->fd].want_read == 0 &&
               sock->manager->fdpollinfo[sock->fd].want_write == 0);
#endif
        UNLOCK(&manager->fdlock[lockid]);

        LOCK(&manager->lock);
        ISC_LIST_APPEND(manager->socklist, sock, link);
#ifdef USE_SELECT
        if (manager->maxfd < sock->fd)
                manager->maxfd = sock->fd;
#endif
        UNLOCK(&manager->lock);

        socket_log(sock, NULL, CREATION, isc_msgcat, ISC_MSGSET_SOCKET,
                   ISC_MSG_CREATED, dup_socket != NULL ? "dupped" : "created");

        return (ISC_R_SUCCESS);
}

/*%
 * Create a new 'type' socket managed by 'manager'.  Events
 * will be posted to 'task' and when dispatched 'action' will be
 * called with 'arg' as the arg value.  The new socket is returned
 * in 'socketp'.
 */
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
                   isc_socket_t **socketp)
{
        return (socket_create(manager0, pf, type, socketp, NULL));
}

/*%
 * Duplicate an existing socket.  The new socket is returned
 * in 'socketp'.
 */
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_dup(isc_socket_t *sock0, isc_socket_t **socketp) {
        isc__socket_t *sock = (isc__socket_t *)sock0;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(socketp != NULL && *socketp == NULL);

        return (socket_create((isc_socketmgr_t *) sock->manager,
                              sock->pf, sock->type, socketp,
                              sock0));
}

#ifdef BIND9
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_open(isc_socket_t *sock0) {
        isc_result_t result;
        isc__socket_t *sock = (isc__socket_t *)sock0;

        REQUIRE(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        REQUIRE(sock->references == 1);
        REQUIRE(sock->type != isc_sockettype_fdwatch);
        UNLOCK(&sock->lock);
        /*
         * We don't need to retain the lock hereafter, since no one else has
         * this socket.
         */
        REQUIRE(sock->fd == -1);

        result = opensocket(sock->manager, sock, NULL);
        if (result != ISC_R_SUCCESS)
                sock->fd = -1;

        if (result == ISC_R_SUCCESS) {
                int lockid = FDLOCK_ID(sock->fd);

                LOCK(&sock->manager->fdlock[lockid]);
                sock->manager->fds[sock->fd] = sock;
                sock->manager->fdstate[sock->fd] = MANAGED;
#if defined(USE_EPOLL)
                sock->manager->epoll_events[sock->fd] = 0;
#endif
#ifdef USE_DEVPOLL
                INSIST(sock->manager->fdpollinfo[sock->fd].want_read == 0 &&
                       sock->manager->fdpollinfo[sock->fd].want_write == 0);
#endif
                UNLOCK(&sock->manager->fdlock[lockid]);

#ifdef USE_SELECT
                LOCK(&sock->manager->lock);
                if (sock->manager->maxfd < sock->fd)
                        sock->manager->maxfd = sock->fd;
                UNLOCK(&sock->manager->lock);
#endif
        }

        return (result);
}
#endif  /* BIND9 */

/*
 * Create a new 'type' socket managed by 'manager'.  Events
 * will be posted to 'task' and when dispatched 'action' will be
 * called with 'arg' as the arg value.  The new socket is returned
 * in 'socketp'.
 */
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_fdwatchcreate(isc_socketmgr_t *manager0, int fd, int flags,
                          isc_sockfdwatch_t callback, void *cbarg,
                          isc_task_t *task, isc_socket_t **socketp)
{
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;
        isc__socket_t *sock = NULL;
        isc_result_t result;
        int lockid;

        REQUIRE(VALID_MANAGER(manager));
        REQUIRE(socketp != NULL && *socketp == NULL);

        if (fd < 0 || (unsigned int)fd >= manager->maxsocks)
                return (ISC_R_RANGE);

        result = allocate_socket(manager, isc_sockettype_fdwatch, &sock);
        if (result != ISC_R_SUCCESS)
                return (result);

        sock->fd = fd;
        sock->fdwatcharg = cbarg;
        sock->fdwatchcb = callback;
        sock->fdwatchflags = flags;
        sock->fdwatchtask = task;
        sock->statsindex = fdwatchstatsindex;

        sock->common.methods = (isc_socketmethods_t *)&socketmethods;
        sock->references = 1;
        *socketp = (isc_socket_t *)sock;

        /*
         * Note we don't have to lock the socket like we normally would because
         * there are no external references to it yet.
         */

        lockid = FDLOCK_ID(sock->fd);
        LOCK(&manager->fdlock[lockid]);
        manager->fds[sock->fd] = sock;
        manager->fdstate[sock->fd] = MANAGED;
#if defined(USE_EPOLL)
        manager->epoll_events[sock->fd] = 0;
#endif
        UNLOCK(&manager->fdlock[lockid]);

        LOCK(&manager->lock);
        ISC_LIST_APPEND(manager->socklist, sock, link);
#ifdef USE_SELECT
        if (manager->maxfd < sock->fd)
                manager->maxfd = sock->fd;
#endif
        UNLOCK(&manager->lock);

        if (flags & ISC_SOCKFDWATCH_READ)
                select_poke(sock->manager, sock->fd, SELECT_POKE_READ);
        if (flags & ISC_SOCKFDWATCH_WRITE)
                select_poke(sock->manager, sock->fd, SELECT_POKE_WRITE);

        socket_log(sock, NULL, CREATION, isc_msgcat, ISC_MSGSET_SOCKET,
                   ISC_MSG_CREATED, "fdwatch-created");

        return (ISC_R_SUCCESS);
}

/*
 * Indicate to the manager that it should watch the socket again.
 * This can be used to restart watching if the previous event handler
 * didn't indicate there was more data to be processed.  Primarily
 * it is for writing but could be used for reading if desired
 */

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_fdwatchpoke(isc_socket_t *sock0, int flags)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;

        REQUIRE(VALID_SOCKET(sock));

        /*
         * We check both flags first to allow us to get the lock
         * once but only if we need it.
         */

        if ((flags & (ISC_SOCKFDWATCH_READ | ISC_SOCKFDWATCH_WRITE)) != 0) {
                LOCK(&sock->lock);
                if (((flags & ISC_SOCKFDWATCH_READ) != 0) &&
                    !sock->pending_recv)
                        select_poke(sock->manager, sock->fd,
                                    SELECT_POKE_READ);
                if (((flags & ISC_SOCKFDWATCH_WRITE) != 0) &&
                    !sock->pending_send)
                        select_poke(sock->manager, sock->fd,
                                    SELECT_POKE_WRITE);
                UNLOCK(&sock->lock);
        }

        socket_log(sock, NULL, TRACE, isc_msgcat, ISC_MSGSET_SOCKET,
                   ISC_MSG_POKED, "fdwatch-poked flags: %d", flags);

        return (ISC_R_SUCCESS);
}

/*
 * Attach to a socket.  Caller must explicitly detach when it is done.
 */
ISC_SOCKETFUNC_SCOPE void
isc__socket_attach(isc_socket_t *sock0, isc_socket_t **socketp) {
        isc__socket_t *sock = (isc__socket_t *)sock0;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(socketp != NULL && *socketp == NULL);

        LOCK(&sock->lock);
        sock->references++;
        UNLOCK(&sock->lock);

        *socketp = (isc_socket_t *)sock;
}

/*
 * Dereference a socket.  If this is the last reference to it, clean things
 * up by destroying the socket.
 */
ISC_SOCKETFUNC_SCOPE void
isc__socket_detach(isc_socket_t **socketp) {
        isc__socket_t *sock;
        isc_boolean_t kill_socket = ISC_FALSE;

        REQUIRE(socketp != NULL);
        sock = (isc__socket_t *)*socketp;
        REQUIRE(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        REQUIRE(sock->references > 0);
        sock->references--;
        if (sock->references == 0)
                kill_socket = ISC_TRUE;
        UNLOCK(&sock->lock);

        if (kill_socket)
                destroy(&sock);

        *socketp = NULL;
}

#ifdef BIND9
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_close(isc_socket_t *sock0) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
        int fd;
        isc__socketmgr_t *manager;

        fflush(stdout);
        REQUIRE(VALID_SOCKET(sock));

        LOCK(&sock->lock);

        REQUIRE(sock->references == 1);
        REQUIRE(sock->type != isc_sockettype_fdwatch);
        REQUIRE(sock->fd >= 0 && sock->fd < (int)sock->manager->maxsocks);

        INSIST(!sock->connecting);
        INSIST(!sock->pending_recv);
        INSIST(!sock->pending_send);
        INSIST(!sock->pending_accept);
        INSIST(ISC_LIST_EMPTY(sock->recv_list));
        INSIST(ISC_LIST_EMPTY(sock->send_list));
        INSIST(ISC_LIST_EMPTY(sock->accept_list));
        INSIST(sock->connect_ev == NULL);

        manager = sock->manager;
        fd = sock->fd;
        sock->fd = -1;
        sock->dupped = 0;
        memset(sock->name, 0, sizeof(sock->name));
        sock->tag = NULL;
        sock->listener = 0;
        sock->connected = 0;
        sock->connecting = 0;
        sock->bound = 0;
        isc_sockaddr_any(&sock->peer_address);

        UNLOCK(&sock->lock);

        socketclose(manager, sock, fd);

        return (ISC_R_SUCCESS);
}
#endif  /* BIND9 */

/*
 * I/O is possible on a given socket.  Schedule an event to this task that
 * will call an internal function to do the I/O.  This will charge the
 * task with the I/O operation and let our select loop handler get back
 * to doing something real as fast as possible.
 *
 * The socket and manager must be locked before calling this function.
 */
static void
dispatch_recv(isc__socket_t *sock) {
        intev_t *iev;
        isc_socketevent_t *ev;
        isc_task_t *sender;

        INSIST(!sock->pending_recv);

        if (sock->type != isc_sockettype_fdwatch) {
                ev = ISC_LIST_HEAD(sock->recv_list);
                if (ev == NULL)
                        return;
                socket_log(sock, NULL, EVENT, NULL, 0, 0,
                           "dispatch_recv:  event %p -> task %p",
                           ev, ev->ev_sender);
                sender = ev->ev_sender;
        } else {
                sender = sock->fdwatchtask;
        }

        sock->pending_recv = 1;
        iev = &sock->readable_ev;

        sock->references++;
        iev->ev_sender = sock;
        if (sock->type == isc_sockettype_fdwatch)
                iev->ev_action = internal_fdwatch_read;
        else
                iev->ev_action = internal_recv;
        iev->ev_arg = sock;

        isc_task_send(sender, (isc_event_t **)&iev);
}

static void
dispatch_send(isc__socket_t *sock) {
        intev_t *iev;
        isc_socketevent_t *ev;
        isc_task_t *sender;

        INSIST(!sock->pending_send);

        if (sock->type != isc_sockettype_fdwatch) {
                ev = ISC_LIST_HEAD(sock->send_list);
                if (ev == NULL)
                        return;
                socket_log(sock, NULL, EVENT, NULL, 0, 0,
                           "dispatch_send:  event %p -> task %p",
                           ev, ev->ev_sender);
                sender = ev->ev_sender;
        } else {
                sender = sock->fdwatchtask;
        }

        sock->pending_send = 1;
        iev = &sock->writable_ev;

        sock->references++;
        iev->ev_sender = sock;
        if (sock->type == isc_sockettype_fdwatch)
                iev->ev_action = internal_fdwatch_write;
        else
                iev->ev_action = internal_send;
        iev->ev_arg = sock;

        isc_task_send(sender, (isc_event_t **)&iev);
}

/*
 * Dispatch an internal accept event.
 */
static void
dispatch_accept(isc__socket_t *sock) {
        intev_t *iev;
        isc_socket_newconnev_t *ev;

        INSIST(!sock->pending_accept);

        /*
         * Are there any done events left, or were they all canceled
         * before the manager got the socket lock?
         */
        ev = ISC_LIST_HEAD(sock->accept_list);
        if (ev == NULL)
                return;

        sock->pending_accept = 1;
        iev = &sock->readable_ev;

        sock->references++;  /* keep socket around for this internal event */
        iev->ev_sender = sock;
        iev->ev_action = internal_accept;
        iev->ev_arg = sock;

        isc_task_send(ev->ev_sender, (isc_event_t **)&iev);
}

static void
dispatch_connect(isc__socket_t *sock) {
        intev_t *iev;
        isc_socket_connev_t *ev;

        iev = &sock->writable_ev;

        ev = sock->connect_ev;
        INSIST(ev != NULL); /* XXX */

        INSIST(sock->connecting);

        sock->references++;  /* keep socket around for this internal event */
        iev->ev_sender = sock;
        iev->ev_action = internal_connect;
        iev->ev_arg = sock;

        isc_task_send(ev->ev_sender, (isc_event_t **)&iev);
}

/*
 * Dequeue an item off the given socket's read queue, set the result code
 * in the done event to the one provided, and send it to the task it was
 * destined for.
 *
 * If the event to be sent is on a list, remove it before sending.  If
 * asked to, send and detach from the socket as well.
 *
 * Caller must have the socket locked if the event is attached to the socket.
 */
static void
send_recvdone_event(isc__socket_t *sock, isc_socketevent_t **dev) {
        isc_task_t *task;

        task = (*dev)->ev_sender;

        (*dev)->ev_sender = sock;

        if (ISC_LINK_LINKED(*dev, ev_link))
                ISC_LIST_DEQUEUE(sock->recv_list, *dev, ev_link);

        if (((*dev)->attributes & ISC_SOCKEVENTATTR_ATTACHED)
            == ISC_SOCKEVENTATTR_ATTACHED)
                isc_task_sendanddetach(&task, (isc_event_t **)dev);
        else
                isc_task_send(task, (isc_event_t **)dev);
}

/*
 * See comments for send_recvdone_event() above.
 *
 * Caller must have the socket locked if the event is attached to the socket.
 */
static void
send_senddone_event(isc__socket_t *sock, isc_socketevent_t **dev) {
        isc_task_t *task;

        INSIST(dev != NULL && *dev != NULL);

        task = (*dev)->ev_sender;
        (*dev)->ev_sender = sock;

        if (ISC_LINK_LINKED(*dev, ev_link))
                ISC_LIST_DEQUEUE(sock->send_list, *dev, ev_link);

        if (((*dev)->attributes & ISC_SOCKEVENTATTR_ATTACHED)
            == ISC_SOCKEVENTATTR_ATTACHED)
                isc_task_sendanddetach(&task, (isc_event_t **)dev);
        else
                isc_task_send(task, (isc_event_t **)dev);
}

/*
 * Call accept() on a socket, to get the new file descriptor.  The listen
 * socket is used as a prototype to create a new isc_socket_t.  The new
 * socket has one outstanding reference.  The task receiving the event
 * will be detached from just after the event is delivered.
 *
 * On entry to this function, the event delivered is the internal
 * readable event, and the first item on the accept_list should be
 * the done event we want to send.  If the list is empty, this is a no-op,
 * so just unlock and return.
 */
static void
internal_accept(isc_task_t *me, isc_event_t *ev) {
        isc__socket_t *sock;
        isc__socketmgr_t *manager;
        isc_socket_newconnev_t *dev;
        isc_task_t *task;
        ISC_SOCKADDR_LEN_T addrlen;
        int fd;
        isc_result_t result = ISC_R_SUCCESS;
        char strbuf[ISC_STRERRORSIZE];
        const char *err = "accept";

        UNUSED(me);

        sock = ev->ev_sender;
        INSIST(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        socket_log(sock, NULL, TRACE,
                   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_ACCEPTLOCK,
                   "internal_accept called, locked socket");

        manager = sock->manager;
        INSIST(VALID_MANAGER(manager));

        INSIST(sock->listener);
        INSIST(sock->pending_accept == 1);
        sock->pending_accept = 0;

        INSIST(sock->references > 0);
        sock->references--;  /* the internal event is done with this socket */
        if (sock->references == 0) {
                UNLOCK(&sock->lock);
                destroy(&sock);
                return;
        }

        /*
         * Get the first item off the accept list.
         * If it is empty, unlock the socket and return.
         */
        dev = ISC_LIST_HEAD(sock->accept_list);
        if (dev == NULL) {
                UNLOCK(&sock->lock);
                return;
        }

        /*
         * Try to accept the new connection.  If the accept fails with
         * EAGAIN or EINTR, simply poke the watcher to watch this socket
         * again.  Also ignore ECONNRESET, which has been reported to
         * be spuriously returned on Linux 2.2.19 although it is not
         * a documented error for accept().  ECONNABORTED has been
         * reported for Solaris 8.  The rest are thrown in not because
         * we have seen them but because they are ignored by other
         * daemons such as BIND 8 and Apache.
         */

        addrlen = sizeof(NEWCONNSOCK(dev)->peer_address.type);
        memset(&NEWCONNSOCK(dev)->peer_address.type, 0, addrlen);
        fd = accept(sock->fd, &NEWCONNSOCK(dev)->peer_address.type.sa,
                    (void *)&addrlen);

#ifdef F_DUPFD
        /*
         * Leave a space for stdio to work in.
         */
        if (fd >= 0 && fd < 20) {
                int new, tmp;
                new = fcntl(fd, F_DUPFD, 20);
                tmp = errno;
                (void)close(fd);
                errno = tmp;
                fd = new;
                err = "accept/fcntl";
        }
#endif

        if (fd < 0) {
                if (SOFT_ERROR(errno))
                        goto soft_error;
                switch (errno) {
                case ENFILE:
                case EMFILE:
                        isc_log_iwrite(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                       ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                                       isc_msgcat, ISC_MSGSET_SOCKET,
                                       ISC_MSG_TOOMANYFDS,
                                       "%s: too many open file descriptors",
                                       err);
                        goto soft_error;

                case ENOBUFS:
                case ENOMEM:
                case ECONNRESET:
                case ECONNABORTED:
                case EHOSTUNREACH:
                case EHOSTDOWN:
                case ENETUNREACH:
                case ENETDOWN:
                case ECONNREFUSED:
#ifdef EPROTO
                case EPROTO:
#endif
#ifdef ENONET
                case ENONET:
#endif
                        goto soft_error;
                default:
                        break;
                }
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "internal_accept: %s() %s: %s", err,
                                 isc_msgcat_get(isc_msgcat,
                                                ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED,
                                                "failed"),
                                 strbuf);
                fd = -1;
                result = ISC_R_UNEXPECTED;
        } else {
                if (addrlen == 0U) {
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "internal_accept(): "
                                         "accept() failed to return "
                                         "remote address");

                        (void)close(fd);
                        goto soft_error;
                } else if (NEWCONNSOCK(dev)->peer_address.type.sa.sa_family !=
                           sock->pf)
                {
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "internal_accept(): "
                                         "accept() returned peer address "
                                         "family %u (expected %u)",
                                         NEWCONNSOCK(dev)->peer_address.
                                         type.sa.sa_family,
                                         sock->pf);
                        (void)close(fd);
                        goto soft_error;
                } else if (fd >= (int)manager->maxsocks) {
                        isc_log_iwrite(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                       ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                                       isc_msgcat, ISC_MSGSET_SOCKET,
                                       ISC_MSG_TOOMANYFDS,
                                       "accept: "
                                       "file descriptor exceeds limit (%d/%u)",
                                       fd, manager->maxsocks);
                        (void)close(fd);
                        goto soft_error;
                }
        }

        if (fd != -1) {
                NEWCONNSOCK(dev)->peer_address.length = addrlen;
                NEWCONNSOCK(dev)->pf = sock->pf;
        }

        /*
         * Pull off the done event.
         */
        ISC_LIST_UNLINK(sock->accept_list, dev, ev_link);

        /*
         * Poke watcher if there are more pending accepts.
         */
        if (!ISC_LIST_EMPTY(sock->accept_list))
                select_poke(sock->manager, sock->fd, SELECT_POKE_ACCEPT);

        UNLOCK(&sock->lock);

        if (fd != -1) {
                result = make_nonblock(fd);
                if (result != ISC_R_SUCCESS) {
                        (void)close(fd);
                        fd = -1;
                }
        }

        /*
         * -1 means the new socket didn't happen.
         */
        if (fd != -1) {
                int lockid = FDLOCK_ID(fd);

                NEWCONNSOCK(dev)->fd = fd;
                NEWCONNSOCK(dev)->bound = 1;
                NEWCONNSOCK(dev)->connected = 1;

                /*
                 * Use minimum mtu if possible.
                 */
                use_min_mtu(NEWCONNSOCK(dev));

                /*
                 * Save away the remote address
                 */
                dev->address = NEWCONNSOCK(dev)->peer_address;

                LOCK(&manager->fdlock[lockid]);
                manager->fds[fd] = NEWCONNSOCK(dev);
                manager->fdstate[fd] = MANAGED;
#if defined(USE_EPOLL)
                manager->epoll_events[fd] = 0;
#endif
                UNLOCK(&manager->fdlock[lockid]);

                LOCK(&manager->lock);

#ifdef USE_SELECT
                if (manager->maxfd < fd)
                        manager->maxfd = fd;
#endif

                socket_log(sock, &NEWCONNSOCK(dev)->peer_address, CREATION,
                           isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_ACCEPTEDCXN,
                           "accepted connection, new socket %p",
                           dev->newsocket);

                ISC_LIST_APPEND(manager->socklist, NEWCONNSOCK(dev), link);

                UNLOCK(&manager->lock);

                inc_stats(manager->stats, sock->statsindex[STATID_ACCEPT]);
        } else {
                inc_stats(manager->stats, sock->statsindex[STATID_ACCEPTFAIL]);
                NEWCONNSOCK(dev)->references--;
                free_socket((isc__socket_t **)&dev->newsocket);
        }

        /*
         * Fill in the done event details and send it off.
         */
        dev->result = result;
        task = dev->ev_sender;
        dev->ev_sender = sock;

        isc_task_sendanddetach(&task, ISC_EVENT_PTR(&dev));
        return;

 soft_error:
        select_poke(sock->manager, sock->fd, SELECT_POKE_ACCEPT);
        UNLOCK(&sock->lock);

        inc_stats(manager->stats, sock->statsindex[STATID_ACCEPTFAIL]);
        return;
}

static void
internal_recv(isc_task_t *me, isc_event_t *ev) {
        isc_socketevent_t *dev;
        isc__socket_t *sock;

        INSIST(ev->ev_type == ISC_SOCKEVENT_INTR);

        sock = ev->ev_sender;
        INSIST(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        socket_log(sock, NULL, IOEVENT,
                   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_INTERNALRECV,
                   "internal_recv: task %p got event %p", me, ev);

        INSIST(sock->pending_recv == 1);
        sock->pending_recv = 0;

        INSIST(sock->references > 0);
        sock->references--;  /* the internal event is done with this socket */
        if (sock->references == 0) {
                UNLOCK(&sock->lock);
                destroy(&sock);
                return;
        }

        /*
         * Try to do as much I/O as possible on this socket.  There are no
         * limits here, currently.
         */
        dev = ISC_LIST_HEAD(sock->recv_list);
        while (dev != NULL) {
                switch (doio_recv(sock, dev)) {
                case DOIO_SOFT:
                        goto poke;

                case DOIO_EOF:
                        /*
                         * read of 0 means the remote end was closed.
                         * Run through the event queue and dispatch all
                         * the events with an EOF result code.
                         */
                        do {
                                dev->result = ISC_R_EOF;
                                send_recvdone_event(sock, &dev);
                                dev = ISC_LIST_HEAD(sock->recv_list);
                        } while (dev != NULL);
                        goto poke;

                case DOIO_SUCCESS:
                case DOIO_HARD:
                        send_recvdone_event(sock, &dev);
                        break;
                }

                dev = ISC_LIST_HEAD(sock->recv_list);
        }

 poke:
        if (!ISC_LIST_EMPTY(sock->recv_list))
                select_poke(sock->manager, sock->fd, SELECT_POKE_READ);

        UNLOCK(&sock->lock);
}

static void
internal_send(isc_task_t *me, isc_event_t *ev) {
        isc_socketevent_t *dev;
        isc__socket_t *sock;

        INSIST(ev->ev_type == ISC_SOCKEVENT_INTW);

        /*
         * Find out what socket this is and lock it.
         */
        sock = (isc__socket_t *)ev->ev_sender;
        INSIST(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        socket_log(sock, NULL, IOEVENT,
                   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_INTERNALSEND,
                   "internal_send: task %p got event %p", me, ev);

        INSIST(sock->pending_send == 1);
        sock->pending_send = 0;

        INSIST(sock->references > 0);
        sock->references--;  /* the internal event is done with this socket */
        if (sock->references == 0) {
                UNLOCK(&sock->lock);
                destroy(&sock);
                return;
        }

        /*
         * Try to do as much I/O as possible on this socket.  There are no
         * limits here, currently.
         */
        dev = ISC_LIST_HEAD(sock->send_list);
        while (dev != NULL) {
                switch (doio_send(sock, dev)) {
                case DOIO_SOFT:
                        goto poke;

                case DOIO_HARD:
                case DOIO_SUCCESS:
                        send_senddone_event(sock, &dev);
                        break;
                }

                dev = ISC_LIST_HEAD(sock->send_list);
        }

 poke:
        if (!ISC_LIST_EMPTY(sock->send_list))
                select_poke(sock->manager, sock->fd, SELECT_POKE_WRITE);

        UNLOCK(&sock->lock);
}

static void
internal_fdwatch_write(isc_task_t *me, isc_event_t *ev) {
        isc__socket_t *sock;
        int more_data;

        INSIST(ev->ev_type == ISC_SOCKEVENT_INTW);

        /*
         * Find out what socket this is and lock it.
         */
        sock = (isc__socket_t *)ev->ev_sender;
        INSIST(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        socket_log(sock, NULL, IOEVENT,
                   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_INTERNALSEND,
                   "internal_fdwatch_write: task %p got event %p", me, ev);

        INSIST(sock->pending_send == 1);

        UNLOCK(&sock->lock);
        more_data = (sock->fdwatchcb)(me, (isc_socket_t *)sock,
                                      sock->fdwatcharg, ISC_SOCKFDWATCH_WRITE);
        LOCK(&sock->lock);

        sock->pending_send = 0;

        INSIST(sock->references > 0);
        sock->references--;  /* the internal event is done with this socket */
        if (sock->references == 0) {
                UNLOCK(&sock->lock);
                destroy(&sock);
                return;
        }

        if (more_data)
                select_poke(sock->manager, sock->fd, SELECT_POKE_WRITE);

        UNLOCK(&sock->lock);
}

static void
internal_fdwatch_read(isc_task_t *me, isc_event_t *ev) {
        isc__socket_t *sock;
        int more_data;

        INSIST(ev->ev_type == ISC_SOCKEVENT_INTR);

        /*
         * Find out what socket this is and lock it.
         */
        sock = (isc__socket_t *)ev->ev_sender;
        INSIST(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        socket_log(sock, NULL, IOEVENT,
                   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_INTERNALRECV,
                   "internal_fdwatch_read: task %p got event %p", me, ev);

        INSIST(sock->pending_recv == 1);

        UNLOCK(&sock->lock);
        more_data = (sock->fdwatchcb)(me, (isc_socket_t *)sock,
                                      sock->fdwatcharg, ISC_SOCKFDWATCH_READ);
        LOCK(&sock->lock);

        sock->pending_recv = 0;

        INSIST(sock->references > 0);
        sock->references--;  /* the internal event is done with this socket */
        if (sock->references == 0) {
                UNLOCK(&sock->lock);
                destroy(&sock);
                return;
        }

        if (more_data)
                select_poke(sock->manager, sock->fd, SELECT_POKE_READ);

        UNLOCK(&sock->lock);
}

/*
 * Process read/writes on each fd here.  Avoid locking
 * and unlocking twice if both reads and writes are possible.
 */
static void
process_fd(isc__socketmgr_t *manager, int fd, isc_boolean_t readable,
           isc_boolean_t writeable)
{
        isc__socket_t *sock;
        isc_boolean_t unlock_sock;
        isc_boolean_t unwatch_read = ISC_FALSE, unwatch_write = ISC_FALSE;
        int lockid = FDLOCK_ID(fd);

        /*
         * If the socket is going to be closed, don't do more I/O.
         */
        LOCK(&manager->fdlock[lockid]);
        if (manager->fdstate[fd] == CLOSE_PENDING) {
                UNLOCK(&manager->fdlock[lockid]);

                (void)unwatch_fd(manager, fd, SELECT_POKE_READ);
                (void)unwatch_fd(manager, fd, SELECT_POKE_WRITE);
                return;
        }

        sock = manager->fds[fd];
        unlock_sock = ISC_FALSE;
        if (readable) {
                if (sock == NULL) {
                        unwatch_read = ISC_TRUE;
                        goto check_write;
                }
                unlock_sock = ISC_TRUE;
                LOCK(&sock->lock);
                if (!SOCK_DEAD(sock)) {
                        if (sock->listener)
                                dispatch_accept(sock);
                        else
                                dispatch_recv(sock);
                }
                unwatch_read = ISC_TRUE;
        }
check_write:
        if (writeable) {
                if (sock == NULL) {
                        unwatch_write = ISC_TRUE;
                        goto unlock_fd;
                }
                if (!unlock_sock) {
                        unlock_sock = ISC_TRUE;
                        LOCK(&sock->lock);
                }
                if (!SOCK_DEAD(sock)) {
                        if (sock->connecting)
                                dispatch_connect(sock);
                        else
                                dispatch_send(sock);
                }
                unwatch_write = ISC_TRUE;
        }
        if (unlock_sock)
                UNLOCK(&sock->lock);

 unlock_fd:
        UNLOCK(&manager->fdlock[lockid]);
        if (unwatch_read)
                (void)unwatch_fd(manager, fd, SELECT_POKE_READ);
        if (unwatch_write)
                (void)unwatch_fd(manager, fd, SELECT_POKE_WRITE);

}

#ifdef USE_KQUEUE
static isc_boolean_t
process_fds(isc__socketmgr_t *manager, struct kevent *events, int nevents) {
        int i;
        isc_boolean_t readable, writable;
        isc_boolean_t done = ISC_FALSE;
#ifdef USE_WATCHER_THREAD
        isc_boolean_t have_ctlevent = ISC_FALSE;
#endif

        if (nevents == manager->nevents) {
                /*
                 * This is not an error, but something unexpected.  If this
                 * happens, it may indicate the need for increasing
                 * ISC_SOCKET_MAXEVENTS.
                 */
                manager_log(manager, ISC_LOGCATEGORY_GENERAL,
                            ISC_LOGMODULE_SOCKET, ISC_LOG_INFO,
                            "maximum number of FD events (%d) received",
                            nevents);
        }

        for (i = 0; i < nevents; i++) {
                REQUIRE(events[i].ident < manager->maxsocks);
#ifdef USE_WATCHER_THREAD
                if (events[i].ident == (uintptr_t)manager->pipe_fds[0]) {
                        have_ctlevent = ISC_TRUE;
                        continue;
                }
#endif
                readable = ISC_TF(events[i].filter == EVFILT_READ);
                writable = ISC_TF(events[i].filter == EVFILT_WRITE);
                process_fd(manager, events[i].ident, readable, writable);
        }

#ifdef USE_WATCHER_THREAD
        if (have_ctlevent)
                done = process_ctlfd(manager);
#endif

        return (done);
}
#elif defined(USE_EPOLL)
static isc_boolean_t
process_fds(isc__socketmgr_t *manager, struct epoll_event *events, int nevents)
{
        int i;
        isc_boolean_t done = ISC_FALSE;
#ifdef USE_WATCHER_THREAD
        isc_boolean_t have_ctlevent = ISC_FALSE;
#endif

        if (nevents == manager->nevents) {
                manager_log(manager, ISC_LOGCATEGORY_GENERAL,
                            ISC_LOGMODULE_SOCKET, ISC_LOG_INFO,
                            "maximum number of FD events (%d) received",
                            nevents);
        }

        for (i = 0; i < nevents; i++) {
                REQUIRE(events[i].data.fd < (int)manager->maxsocks);
#ifdef USE_WATCHER_THREAD
                if (events[i].data.fd == manager->pipe_fds[0]) {
                        have_ctlevent = ISC_TRUE;
                        continue;
                }
#endif
                if ((events[i].events & EPOLLERR) != 0 ||
                    (events[i].events & EPOLLHUP) != 0) {
                        /*
                         * epoll does not set IN/OUT bits on an erroneous
                         * condition, so we need to try both anyway.  This is a
                         * bit inefficient, but should be okay for such rare
                         * events.  Note also that the read or write attempt
                         * won't block because we use non-blocking sockets.
                         */
                        events[i].events |= (EPOLLIN | EPOLLOUT);
                }
                process_fd(manager, events[i].data.fd,
                           (events[i].events & EPOLLIN) != 0,
                           (events[i].events & EPOLLOUT) != 0);
        }

#ifdef USE_WATCHER_THREAD
        if (have_ctlevent)
                done = process_ctlfd(manager);
#endif

        return (done);
}
#elif defined(USE_DEVPOLL)
static isc_boolean_t
process_fds(isc__socketmgr_t *manager, struct pollfd *events, int nevents) {
        int i;
        isc_boolean_t done = ISC_FALSE;
#ifdef USE_WATCHER_THREAD
        isc_boolean_t have_ctlevent = ISC_FALSE;
#endif

        if (nevents == manager->nevents) {
                manager_log(manager, ISC_LOGCATEGORY_GENERAL,
                            ISC_LOGMODULE_SOCKET, ISC_LOG_INFO,
                            "maximum number of FD events (%d) received",
                            nevents);
        }

        for (i = 0; i < nevents; i++) {
                REQUIRE(events[i].fd < (int)manager->maxsocks);
#ifdef USE_WATCHER_THREAD
                if (events[i].fd == manager->pipe_fds[0]) {
                        have_ctlevent = ISC_TRUE;
                        continue;
                }
#endif
                process_fd(manager, events[i].fd,
                           (events[i].events & POLLIN) != 0,
                           (events[i].events & POLLOUT) != 0);
        }

#ifdef USE_WATCHER_THREAD
        if (have_ctlevent)
                done = process_ctlfd(manager);
#endif

        return (done);
}
#elif defined(USE_SELECT)
static void
process_fds(isc__socketmgr_t *manager, int maxfd, fd_set *readfds,
            fd_set *writefds)
{
        int i;

        REQUIRE(maxfd <= (int)manager->maxsocks);

        for (i = 0; i < maxfd; i++) {
#ifdef USE_WATCHER_THREAD
                if (i == manager->pipe_fds[0] || i == manager->pipe_fds[1])
                        continue;
#endif /* USE_WATCHER_THREAD */
                process_fd(manager, i, FD_ISSET(i, readfds),
                           FD_ISSET(i, writefds));
        }
}
#endif

#ifdef USE_WATCHER_THREAD
static isc_boolean_t
process_ctlfd(isc__socketmgr_t *manager) {
        int msg, fd;

        for (;;) {
                select_readmsg(manager, &fd, &msg);

                manager_log(manager, IOEVENT,
                            isc_msgcat_get(isc_msgcat, ISC_MSGSET_SOCKET,
                                           ISC_MSG_WATCHERMSG,
                                           "watcher got message %d "
                                           "for socket %d"), msg, fd);

                /*
                 * Nothing to read?
                 */
                if (msg == SELECT_POKE_NOTHING)
                        break;

                /*
                 * Handle shutdown message.  We really should
                 * jump out of this loop right away, but
                 * it doesn't matter if we have to do a little
                 * more work first.
                 */
                if (msg == SELECT_POKE_SHUTDOWN)
                        return (ISC_TRUE);

                /*
                 * This is a wakeup on a socket.  Look
                 * at the event queue for both read and write,
                 * and decide if we need to watch on it now
                 * or not.
                 */
                wakeup_socket(manager, fd, msg);
        }

        return (ISC_FALSE);
}

/*
 * This is the thread that will loop forever, always in a select or poll
 * call.
 *
 * When select returns something to do, track down what thread gets to do
 * this I/O and post the event to it.
 */
static isc_threadresult_t
watcher(void *uap) {
        isc__socketmgr_t *manager = uap;
        isc_boolean_t done;
        int cc;
#ifdef USE_KQUEUE
        const char *fnname = "kevent()";
#elif defined (USE_EPOLL)
        const char *fnname = "epoll_wait()";
#elif defined(USE_DEVPOLL)
        isc_result_t result;
        const char *fnname = "ioctl(DP_POLL)";
        struct dvpoll dvp;
        int pass;
#elif defined (USE_SELECT)
        const char *fnname = "select()";
        int maxfd;
        int ctlfd;
#endif
        char strbuf[ISC_STRERRORSIZE];
#ifdef ISC_SOCKET_USE_POLLWATCH
        pollstate_t pollstate = poll_idle;
#endif

#if defined (USE_SELECT)
        /*
         * Get the control fd here.  This will never change.
         */
        ctlfd = manager->pipe_fds[0];
#endif
        done = ISC_FALSE;
        while (!done) {
                do {
#ifdef USE_KQUEUE
                        cc = kevent(manager->kqueue_fd, NULL, 0,
                                    manager->events, manager->nevents, NULL);
#elif defined(USE_EPOLL)
                        cc = epoll_wait(manager->epoll_fd, manager->events,
                                        manager->nevents, -1);
#elif defined(USE_DEVPOLL)
                        /*
                         * Re-probe every thousand calls.
                         */
                        if (manager->calls++ > 1000U) {
                                result = isc_resource_getcurlimit(
                                                        isc_resource_openfiles,
                                                        &manager->open_max);
                                if (result != ISC_R_SUCCESS)
                                        manager->open_max = 64;
                                manager->calls = 0;
                        }
                        for (pass = 0; pass < 2; pass++) {
                                dvp.dp_fds = manager->events;
                                dvp.dp_nfds = manager->nevents;
                                if (dvp.dp_nfds >= manager->open_max)
                                        dvp.dp_nfds = manager->open_max - 1;
#ifndef ISC_SOCKET_USE_POLLWATCH
                                dvp.dp_timeout = -1;
#else
                                if (pollstate == poll_idle)
                                        dvp.dp_timeout = -1;
                                else
                                        dvp.dp_timeout =
                                                 ISC_SOCKET_POLLWATCH_TIMEOUT;
#endif  /* ISC_SOCKET_USE_POLLWATCH */
                                cc = ioctl(manager->devpoll_fd, DP_POLL, &dvp);
                                if (cc == -1 && errno == EINVAL) {
                                        /*
                                         * {OPEN_MAX} may have dropped.  Look
                                         * up the current value and try again.
                                         */
                                        result = isc_resource_getcurlimit(
                                                        isc_resource_openfiles,
                                                        &manager->open_max);
                                        if (result != ISC_R_SUCCESS)
                                                manager->open_max = 64;
                                } else
                                        break;
                        }
#elif defined(USE_SELECT)
                        LOCK(&manager->lock);
                        memmove(manager->read_fds_copy, manager->read_fds,
                                manager->fd_bufsize);
                        memmove(manager->write_fds_copy, manager->write_fds,
                                manager->fd_bufsize);
                        maxfd = manager->maxfd + 1;
                        UNLOCK(&manager->lock);

                        cc = select(maxfd, manager->read_fds_copy,
                                    manager->write_fds_copy, NULL, NULL);
#endif  /* USE_KQUEUE */

                        if (cc < 0 && !SOFT_ERROR(errno)) {
                                isc__strerror(errno, strbuf, sizeof(strbuf));
                                FATAL_ERROR(__FILE__, __LINE__,
                                            "%s %s: %s", fnname,
                                            isc_msgcat_get(isc_msgcat,
                                                           ISC_MSGSET_GENERAL,
                                                           ISC_MSG_FAILED,
                                                           "failed"), strbuf);
                        }

#if defined(USE_DEVPOLL) && defined(ISC_SOCKET_USE_POLLWATCH)
                        if (cc == 0) {
                                if (pollstate == poll_active)
                                        pollstate = poll_checking;
                                else if (pollstate == poll_checking)
                                        pollstate = poll_idle;
                        } else if (cc > 0) {
                                if (pollstate == poll_checking) {
                                        /*
                                         * XXX: We'd like to use a more
                                         * verbose log level as it's actually an
                                         * unexpected event, but the kernel bug
                                         * reportedly happens pretty frequently
                                         * (and it can also be a false positive)
                                         * so it would be just too noisy.
                                         */
                                        manager_log(manager,
                                                    ISC_LOGCATEGORY_GENERAL,
                                                    ISC_LOGMODULE_SOCKET,
                                                    ISC_LOG_DEBUG(1),
                                                    "unexpected POLL timeout");
                                }
                                pollstate = poll_active;
                        }
#endif
                } while (cc < 0);

#if defined(USE_KQUEUE) || defined (USE_EPOLL) || defined (USE_DEVPOLL)
                done = process_fds(manager, manager->events, cc);
#elif defined(USE_SELECT)
                process_fds(manager, maxfd, manager->read_fds_copy,
                            manager->write_fds_copy);

                /*
                 * Process reads on internal, control fd.
                 */
                if (FD_ISSET(ctlfd, manager->read_fds_copy))
                        done = process_ctlfd(manager);
#endif
        }

        manager_log(manager, TRACE, "%s",
                    isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                   ISC_MSG_EXITING, "watcher exiting"));

        return ((isc_threadresult_t)0);
}
#endif /* USE_WATCHER_THREAD */

#ifdef BIND9
ISC_SOCKETFUNC_SCOPE void
isc__socketmgr_setreserved(isc_socketmgr_t *manager0, isc_uint32_t reserved) {
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;

        REQUIRE(VALID_MANAGER(manager));

        manager->reserved = reserved;
}

ISC_SOCKETFUNC_SCOPE void
isc___socketmgr_maxudp(isc_socketmgr_t *manager0, int maxudp) {
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;

        REQUIRE(VALID_MANAGER(manager));

        manager->maxudp = maxudp;
}
#endif  /* BIND9 */

/*
 * Create a new socket manager.
 */

static isc_result_t
setup_watcher(isc_mem_t *mctx, isc__socketmgr_t *manager) {
        isc_result_t result;
#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
        char strbuf[ISC_STRERRORSIZE];
#endif

#ifdef USE_KQUEUE
        manager->nevents = ISC_SOCKET_MAXEVENTS;
        manager->events = isc_mem_get(mctx, sizeof(struct kevent) *
                                      manager->nevents);
        if (manager->events == NULL)
                return (ISC_R_NOMEMORY);
        manager->kqueue_fd = kqueue();
        if (manager->kqueue_fd == -1) {
                result = isc__errno2result(errno);
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "kqueue %s: %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"),
                                 strbuf);
                isc_mem_put(mctx, manager->events,
                            sizeof(struct kevent) * manager->nevents);
                return (result);
        }

#ifdef USE_WATCHER_THREAD
        result = watch_fd(manager, manager->pipe_fds[0], SELECT_POKE_READ);
        if (result != ISC_R_SUCCESS) {
                close(manager->kqueue_fd);
                isc_mem_put(mctx, manager->events,
                            sizeof(struct kevent) * manager->nevents);
                return (result);
        }
#endif  /* USE_WATCHER_THREAD */
#elif defined(USE_EPOLL)
        manager->nevents = ISC_SOCKET_MAXEVENTS;
        manager->events = isc_mem_get(mctx, sizeof(struct epoll_event) *
                                      manager->nevents);
        if (manager->events == NULL)
                return (ISC_R_NOMEMORY);
        manager->epoll_fd = epoll_create(manager->nevents);
        if (manager->epoll_fd == -1) {
                result = isc__errno2result(errno);
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "epoll_create %s: %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"),
                                 strbuf);
                isc_mem_put(mctx, manager->events,
                            sizeof(struct epoll_event) * manager->nevents);
                return (result);
        }
#ifdef USE_WATCHER_THREAD
        result = watch_fd(manager, manager->pipe_fds[0], SELECT_POKE_READ);
        if (result != ISC_R_SUCCESS) {
                close(manager->epoll_fd);
                isc_mem_put(mctx, manager->events,
                            sizeof(struct epoll_event) * manager->nevents);
                return (result);
        }
#endif  /* USE_WATCHER_THREAD */
#elif defined(USE_DEVPOLL)
        manager->nevents = ISC_SOCKET_MAXEVENTS;
        result = isc_resource_getcurlimit(isc_resource_openfiles,
                                          &manager->open_max);
        if (result != ISC_R_SUCCESS)
                manager->open_max = 64;
        manager->calls = 0;
        manager->events = isc_mem_get(mctx, sizeof(struct pollfd) *
                                      manager->nevents);
        if (manager->events == NULL)
                return (ISC_R_NOMEMORY);
        /*
         * Note: fdpollinfo should be able to support all possible FDs, so
         * it must have maxsocks entries (not nevents).
         */
        manager->fdpollinfo = isc_mem_get(mctx, sizeof(pollinfo_t) *
                                          manager->maxsocks);
        if (manager->fdpollinfo == NULL) {
                isc_mem_put(mctx, manager->events,
                            sizeof(struct pollfd) * manager->nevents);
                return (ISC_R_NOMEMORY);
        }
        memset(manager->fdpollinfo, 0, sizeof(pollinfo_t) * manager->maxsocks);
        manager->devpoll_fd = open("/dev/poll", O_RDWR);
        if (manager->devpoll_fd == -1) {
                result = isc__errno2result(errno);
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "open(/dev/poll) %s: %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"),
                                 strbuf);
                isc_mem_put(mctx, manager->events,
                            sizeof(struct pollfd) * manager->nevents);
                isc_mem_put(mctx, manager->fdpollinfo,
                            sizeof(pollinfo_t) * manager->maxsocks);
                return (result);
        }
#ifdef USE_WATCHER_THREAD
        result = watch_fd(manager, manager->pipe_fds[0], SELECT_POKE_READ);
        if (result != ISC_R_SUCCESS) {
                close(manager->devpoll_fd);
                isc_mem_put(mctx, manager->events,
                            sizeof(struct pollfd) * manager->nevents);
                isc_mem_put(mctx, manager->fdpollinfo,
                            sizeof(pollinfo_t) * manager->maxsocks);
                return (result);
        }
#endif  /* USE_WATCHER_THREAD */
#elif defined(USE_SELECT)
        UNUSED(result);

#if ISC_SOCKET_MAXSOCKETS > FD_SETSIZE
        /*
         * Note: this code should also cover the case of MAXSOCKETS <=
         * FD_SETSIZE, but we separate the cases to avoid possible portability
         * issues regarding howmany() and the actual representation of fd_set.
         */
        manager->fd_bufsize = howmany(manager->maxsocks, NFDBITS) *
                sizeof(fd_mask);
#else
        manager->fd_bufsize = sizeof(fd_set);
#endif

        manager->read_fds = NULL;
        manager->read_fds_copy = NULL;
        manager->write_fds = NULL;
        manager->write_fds_copy = NULL;

        manager->read_fds = isc_mem_get(mctx, manager->fd_bufsize);
        if (manager->read_fds != NULL)
                manager->read_fds_copy = isc_mem_get(mctx, manager->fd_bufsize);
        if (manager->read_fds_copy != NULL)
                manager->write_fds = isc_mem_get(mctx, manager->fd_bufsize);
        if (manager->write_fds != NULL) {
                manager->write_fds_copy = isc_mem_get(mctx,
                                                      manager->fd_bufsize);
        }
        if (manager->write_fds_copy == NULL) {
                if (manager->write_fds != NULL) {
                        isc_mem_put(mctx, manager->write_fds,
                                    manager->fd_bufsize);
                }
                if (manager->read_fds_copy != NULL) {
                        isc_mem_put(mctx, manager->read_fds_copy,
                                    manager->fd_bufsize);
                }
                if (manager->read_fds != NULL) {
                        isc_mem_put(mctx, manager->read_fds,
                                    manager->fd_bufsize);
                }
                return (ISC_R_NOMEMORY);
        }
        memset(manager->read_fds, 0, manager->fd_bufsize);
        memset(manager->write_fds, 0, manager->fd_bufsize);

#ifdef USE_WATCHER_THREAD
        (void)watch_fd(manager, manager->pipe_fds[0], SELECT_POKE_READ);
        manager->maxfd = manager->pipe_fds[0];
#else /* USE_WATCHER_THREAD */
        manager->maxfd = 0;
#endif /* USE_WATCHER_THREAD */
#endif  /* USE_KQUEUE */

        return (ISC_R_SUCCESS);
}

static void
cleanup_watcher(isc_mem_t *mctx, isc__socketmgr_t *manager) {
#ifdef USE_WATCHER_THREAD
        isc_result_t result;

        result = unwatch_fd(manager, manager->pipe_fds[0], SELECT_POKE_READ);
        if (result != ISC_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "epoll_ctl(DEL) %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"));
        }
#endif  /* USE_WATCHER_THREAD */

#ifdef USE_KQUEUE
        close(manager->kqueue_fd);
        isc_mem_put(mctx, manager->events,
                    sizeof(struct kevent) * manager->nevents);
#elif defined(USE_EPOLL)
        close(manager->epoll_fd);
        isc_mem_put(mctx, manager->events,
                    sizeof(struct epoll_event) * manager->nevents);
#elif defined(USE_DEVPOLL)
        close(manager->devpoll_fd);
        isc_mem_put(mctx, manager->events,
                    sizeof(struct pollfd) * manager->nevents);
        isc_mem_put(mctx, manager->fdpollinfo,
                    sizeof(pollinfo_t) * manager->maxsocks);
#elif defined(USE_SELECT)
        if (manager->read_fds != NULL)
                isc_mem_put(mctx, manager->read_fds, manager->fd_bufsize);
        if (manager->read_fds_copy != NULL)
                isc_mem_put(mctx, manager->read_fds_copy, manager->fd_bufsize);
        if (manager->write_fds != NULL)
                isc_mem_put(mctx, manager->write_fds, manager->fd_bufsize);
        if (manager->write_fds_copy != NULL)
                isc_mem_put(mctx, manager->write_fds_copy, manager->fd_bufsize);
#endif  /* USE_KQUEUE */
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socketmgr_create(isc_mem_t *mctx, isc_socketmgr_t **managerp) {
        return (isc__socketmgr_create2(mctx, managerp, 0));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socketmgr_create2(isc_mem_t *mctx, isc_socketmgr_t **managerp,
                       unsigned int maxsocks)
{
        int i;
        isc__socketmgr_t *manager;
#ifdef USE_WATCHER_THREAD
        char strbuf[ISC_STRERRORSIZE];
#endif
        isc_result_t result;

        REQUIRE(managerp != NULL && *managerp == NULL);

#ifdef USE_SHARED_MANAGER
        if (socketmgr != NULL) {
                /* Don't allow maxsocks to be updated */
                if (maxsocks > 0 && socketmgr->maxsocks != maxsocks)
                        return (ISC_R_EXISTS);

                socketmgr->refs++;
                *managerp = (isc_socketmgr_t *)socketmgr;
                return (ISC_R_SUCCESS);
        }
#endif /* USE_SHARED_MANAGER */

        if (maxsocks == 0)
                maxsocks = ISC_SOCKET_MAXSOCKETS;

        manager = isc_mem_get(mctx, sizeof(*manager));
        if (manager == NULL)
                return (ISC_R_NOMEMORY);

        /* zero-clear so that necessary cleanup on failure will be easy */
        memset(manager, 0, sizeof(*manager));
        manager->maxsocks = maxsocks;
        manager->reserved = 0;
        manager->maxudp = 0;
        manager->fds = isc_mem_get(mctx,
                                   manager->maxsocks * sizeof(isc__socket_t *));
        if (manager->fds == NULL) {
                result = ISC_R_NOMEMORY;
                goto free_manager;
        }
        manager->fdstate = isc_mem_get(mctx, manager->maxsocks * sizeof(int));
        if (manager->fdstate == NULL) {
                result = ISC_R_NOMEMORY;
                goto free_manager;
        }
#if defined(USE_EPOLL)
        manager->epoll_events = isc_mem_get(mctx, (manager->maxsocks *
                                                   sizeof(uint32_t)));
        if (manager->epoll_events == NULL) {
                result = ISC_R_NOMEMORY;
                goto free_manager;
        }
        memset(manager->epoll_events, 0, manager->maxsocks * sizeof(uint32_t));
#endif
        manager->stats = NULL;

        manager->common.methods = &socketmgrmethods;
        manager->common.magic = ISCAPI_SOCKETMGR_MAGIC;
        manager->common.impmagic = SOCKET_MANAGER_MAGIC;
        manager->mctx = NULL;
        memset(manager->fds, 0, manager->maxsocks * sizeof(isc_socket_t *));
        ISC_LIST_INIT(manager->socklist);
        result = isc_mutex_init(&manager->lock);
        if (result != ISC_R_SUCCESS)
                goto free_manager;
        manager->fdlock = isc_mem_get(mctx, FDLOCK_COUNT * sizeof(isc_mutex_t));
        if (manager->fdlock == NULL) {
                result = ISC_R_NOMEMORY;
                goto cleanup_lock;
        }
        for (i = 0; i < FDLOCK_COUNT; i++) {
                result = isc_mutex_init(&manager->fdlock[i]);
                if (result != ISC_R_SUCCESS) {
                        while (--i >= 0)
                                DESTROYLOCK(&manager->fdlock[i]);
                        isc_mem_put(mctx, manager->fdlock,
                                    FDLOCK_COUNT * sizeof(isc_mutex_t));
                        manager->fdlock = NULL;
                        goto cleanup_lock;
                }
        }

#ifdef USE_WATCHER_THREAD
        if (isc_condition_init(&manager->shutdown_ok) != ISC_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "isc_condition_init() %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"));
                result = ISC_R_UNEXPECTED;
                goto cleanup_lock;
        }

        /*
         * Create the special fds that will be used to wake up the
         * select/poll loop when something internal needs to be done.
         */
        if (pipe(manager->pipe_fds) != 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "pipe() %s: %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"),
                                 strbuf);
                result = ISC_R_UNEXPECTED;
                goto cleanup_condition;
        }

        RUNTIME_CHECK(make_nonblock(manager->pipe_fds[0]) == ISC_R_SUCCESS);
#if 0
        RUNTIME_CHECK(make_nonblock(manager->pipe_fds[1]) == ISC_R_SUCCESS);
#endif
#endif  /* USE_WATCHER_THREAD */

#ifdef USE_SHARED_MANAGER
        manager->refs = 1;
#endif /* USE_SHARED_MANAGER */

        /*
         * Set up initial state for the select loop
         */
        result = setup_watcher(mctx, manager);
        if (result != ISC_R_SUCCESS)
                goto cleanup;

        memset(manager->fdstate, 0, manager->maxsocks * sizeof(int));

#ifdef USE_WATCHER_THREAD
        /*
         * Start up the select/poll thread.
         */
        if (isc_thread_create(watcher, manager, &manager->watcher) !=
            ISC_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "isc_thread_create() %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"));
                cleanup_watcher(mctx, manager);
                result = ISC_R_UNEXPECTED;
                goto cleanup;
        }
#endif /* USE_WATCHER_THREAD */
        isc_mem_attach(mctx, &manager->mctx);

#ifdef USE_SHARED_MANAGER
        socketmgr = manager;
#endif /* USE_SHARED_MANAGER */
        *managerp = (isc_socketmgr_t *)manager;

        return (ISC_R_SUCCESS);

cleanup:
#ifdef USE_WATCHER_THREAD
        (void)close(manager->pipe_fds[0]);
        (void)close(manager->pipe_fds[1]);
#endif  /* USE_WATCHER_THREAD */

#ifdef USE_WATCHER_THREAD
cleanup_condition:
        (void)isc_condition_destroy(&manager->shutdown_ok);
#endif  /* USE_WATCHER_THREAD */


cleanup_lock:
        if (manager->fdlock != NULL) {
                for (i = 0; i < FDLOCK_COUNT; i++)
                        DESTROYLOCK(&manager->fdlock[i]);
        }
        DESTROYLOCK(&manager->lock);

free_manager:
        if (manager->fdlock != NULL) {
                isc_mem_put(mctx, manager->fdlock,
                            FDLOCK_COUNT * sizeof(isc_mutex_t));
        }
#if defined(USE_EPOLL)
        if (manager->epoll_events != NULL) {
                isc_mem_put(mctx, manager->epoll_events,
                            manager->maxsocks * sizeof(uint32_t));
        }
#endif
        if (manager->fdstate != NULL) {
                isc_mem_put(mctx, manager->fdstate,
                            manager->maxsocks * sizeof(int));
        }
        if (manager->fds != NULL) {
                isc_mem_put(mctx, manager->fds,
                            manager->maxsocks * sizeof(isc_socket_t *));
        }
        isc_mem_put(mctx, manager, sizeof(*manager));

        return (result);
}

#ifdef BIND9
isc_result_t
isc__socketmgr_getmaxsockets(isc_socketmgr_t *manager0, unsigned int *nsockp) {
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;
        REQUIRE(VALID_MANAGER(manager));
        REQUIRE(nsockp != NULL);

        *nsockp = manager->maxsocks;

        return (ISC_R_SUCCESS);
}

void
isc__socketmgr_setstats(isc_socketmgr_t *manager0, isc_stats_t *stats) {
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;

        REQUIRE(VALID_MANAGER(manager));
        REQUIRE(ISC_LIST_EMPTY(manager->socklist));
        REQUIRE(manager->stats == NULL);
        REQUIRE(isc_stats_ncounters(stats) == isc_sockstatscounter_max);

        isc_stats_attach(stats, &manager->stats);
}
#endif

ISC_SOCKETFUNC_SCOPE void
isc__socketmgr_destroy(isc_socketmgr_t **managerp) {
        isc__socketmgr_t *manager;
        int i;
        isc_mem_t *mctx;

        /*
         * Destroy a socket manager.
         */

        REQUIRE(managerp != NULL);
        manager = (isc__socketmgr_t *)*managerp;
        REQUIRE(VALID_MANAGER(manager));

#ifdef USE_SHARED_MANAGER
        manager->refs--;
        if (manager->refs > 0) {
                *managerp = NULL;
                return;
        }
        socketmgr = NULL;
#endif /* USE_SHARED_MANAGER */

        LOCK(&manager->lock);

        /*
         * Wait for all sockets to be destroyed.
         */
        while (!ISC_LIST_EMPTY(manager->socklist)) {
#ifdef USE_WATCHER_THREAD
                manager_log(manager, CREATION, "%s",
                            isc_msgcat_get(isc_msgcat, ISC_MSGSET_SOCKET,
                                           ISC_MSG_SOCKETSREMAIN,
                                           "sockets exist"));
                WAIT(&manager->shutdown_ok, &manager->lock);
#else /* USE_WATCHER_THREAD */
                UNLOCK(&manager->lock);
                isc__taskmgr_dispatch(NULL);
                LOCK(&manager->lock);
#endif /* USE_WATCHER_THREAD */
        }

        UNLOCK(&manager->lock);

        /*
         * Here, poke our select/poll thread.  Do this by closing the write
         * half of the pipe, which will send EOF to the read half.
         * This is currently a no-op in the non-threaded case.
         */
        select_poke(manager, 0, SELECT_POKE_SHUTDOWN);

#ifdef USE_WATCHER_THREAD
        /*
         * Wait for thread to exit.
         */
        if (isc_thread_join(manager->watcher, NULL) != ISC_R_SUCCESS)
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "isc_thread_join() %s",
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"));
#endif /* USE_WATCHER_THREAD */

        /*
         * Clean up.
         */
        cleanup_watcher(manager->mctx, manager);

#ifdef USE_WATCHER_THREAD
        (void)close(manager->pipe_fds[0]);
        (void)close(manager->pipe_fds[1]);
        (void)isc_condition_destroy(&manager->shutdown_ok);
#endif /* USE_WATCHER_THREAD */

        for (i = 0; i < (int)manager->maxsocks; i++)
                if (manager->fdstate[i] == CLOSE_PENDING) /* no need to lock */
                        (void)close(i);

#if defined(USE_EPOLL)
        isc_mem_put(manager->mctx, manager->epoll_events,
                    manager->maxsocks * sizeof(uint32_t));
#endif
        isc_mem_put(manager->mctx, manager->fds,
                    manager->maxsocks * sizeof(isc__socket_t *));
        isc_mem_put(manager->mctx, manager->fdstate,
                    manager->maxsocks * sizeof(int));

        if (manager->stats != NULL)
                isc_stats_detach(&manager->stats);

        if (manager->fdlock != NULL) {
                for (i = 0; i < FDLOCK_COUNT; i++)
                        DESTROYLOCK(&manager->fdlock[i]);
                isc_mem_put(manager->mctx, manager->fdlock,
                            FDLOCK_COUNT * sizeof(isc_mutex_t));
        }
        DESTROYLOCK(&manager->lock);
        manager->common.magic = 0;
        manager->common.impmagic = 0;
        mctx= manager->mctx;
        isc_mem_put(mctx, manager, sizeof(*manager));

        isc_mem_detach(&mctx);

        *managerp = NULL;

#ifdef USE_SHARED_MANAGER
        socketmgr = NULL;
#endif
}

static isc_result_t
socket_recv(isc__socket_t *sock, isc_socketevent_t *dev, isc_task_t *task,
            unsigned int flags)
{
        int io_state;
        isc_boolean_t have_lock = ISC_FALSE;
        isc_task_t *ntask = NULL;
        isc_result_t result = ISC_R_SUCCESS;

        dev->ev_sender = task;

        if (sock->type == isc_sockettype_udp) {
                io_state = doio_recv(sock, dev);
        } else {
                LOCK(&sock->lock);
                have_lock = ISC_TRUE;

                if (ISC_LIST_EMPTY(sock->recv_list))
                        io_state = doio_recv(sock, dev);
                else
                        io_state = DOIO_SOFT;
        }

        switch (io_state) {
        case DOIO_SOFT:
                /*
                 * We couldn't read all or part of the request right now, so
                 * queue it.
                 *
                 * Attach to socket and to task
                 */
                isc_task_attach(task, &ntask);
                dev->attributes |= ISC_SOCKEVENTATTR_ATTACHED;

                if (!have_lock) {
                        LOCK(&sock->lock);
                        have_lock = ISC_TRUE;
                }

                /*
                 * Enqueue the request.  If the socket was previously not being
                 * watched, poke the watcher to start paying attention to it.
                 */
                if (ISC_LIST_EMPTY(sock->recv_list) && !sock->pending_recv)
                        select_poke(sock->manager, sock->fd, SELECT_POKE_READ);
                ISC_LIST_ENQUEUE(sock->recv_list, dev, ev_link);

                socket_log(sock, NULL, EVENT, NULL, 0, 0,
                           "socket_recv: event %p -> task %p",
                           dev, ntask);

                if ((flags & ISC_SOCKFLAG_IMMEDIATE) != 0)
                        result = ISC_R_INPROGRESS;
                break;

        case DOIO_EOF:
                dev->result = ISC_R_EOF;
                /* fallthrough */

        case DOIO_HARD:
        case DOIO_SUCCESS:
                if ((flags & ISC_SOCKFLAG_IMMEDIATE) == 0)
                        send_recvdone_event(sock, &dev);
                break;
        }

        if (have_lock)
                UNLOCK(&sock->lock);

        return (result);
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_recvv(isc_socket_t *sock0, isc_bufferlist_t *buflist,
                  unsigned int minimum, isc_task_t *task,
                  isc_taskaction_t action, void *arg)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_socketevent_t *dev;
        isc__socketmgr_t *manager;
        unsigned int iocount;
        isc_buffer_t *buffer;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(buflist != NULL);
        REQUIRE(!ISC_LIST_EMPTY(*buflist));
        REQUIRE(task != NULL);
        REQUIRE(action != NULL);

        manager = sock->manager;
        REQUIRE(VALID_MANAGER(manager));

        iocount = isc_bufferlist_availablecount(buflist);
        REQUIRE(iocount > 0);

        INSIST(sock->bound);

        dev = allocate_socketevent(sock, ISC_SOCKEVENT_RECVDONE, action, arg);
        if (dev == NULL)
                return (ISC_R_NOMEMORY);

        /*
         * UDP sockets are always partial read
         */
        if (sock->type == isc_sockettype_udp)
                dev->minimum = 1;
        else {
                if (minimum == 0)
                        dev->minimum = iocount;
                else
                        dev->minimum = minimum;
        }

        /*
         * Move each buffer from the passed in list to our internal one.
         */
        buffer = ISC_LIST_HEAD(*buflist);
        while (buffer != NULL) {
                ISC_LIST_DEQUEUE(*buflist, buffer, link);
                ISC_LIST_ENQUEUE(dev->bufferlist, buffer, link);
                buffer = ISC_LIST_HEAD(*buflist);
        }

        return (socket_recv(sock, dev, task, 0));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_recv(isc_socket_t *sock0, isc_region_t *region,
                 unsigned int minimum, isc_task_t *task,
                 isc_taskaction_t action, void *arg)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_socketevent_t *dev;
        isc__socketmgr_t *manager;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(action != NULL);

        manager = sock->manager;
        REQUIRE(VALID_MANAGER(manager));

        INSIST(sock->bound);

        dev = allocate_socketevent(sock, ISC_SOCKEVENT_RECVDONE, action, arg);
        if (dev == NULL)
                return (ISC_R_NOMEMORY);

        return (isc__socket_recv2(sock0, region, minimum, task, dev, 0));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_recv2(isc_socket_t *sock0, isc_region_t *region,
                  unsigned int minimum, isc_task_t *task,
                  isc_socketevent_t *event, unsigned int flags)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;

        event->ev_sender = sock;
        event->result = ISC_R_UNSET;
        ISC_LIST_INIT(event->bufferlist);
        event->region = *region;
        event->n = 0;
        event->offset = 0;
        event->attributes = 0;

        /*
         * UDP sockets are always partial read.
         */
        if (sock->type == isc_sockettype_udp)
                event->minimum = 1;
        else {
                if (minimum == 0)
                        event->minimum = region->length;
                else
                        event->minimum = minimum;
        }

        return (socket_recv(sock, event, task, flags));
}

static isc_result_t
socket_send(isc__socket_t *sock, isc_socketevent_t *dev, isc_task_t *task,
            isc_sockaddr_t *address, struct in6_pktinfo *pktinfo,
            unsigned int flags)
{
        int io_state;
        isc_boolean_t have_lock = ISC_FALSE;
        isc_task_t *ntask = NULL;
        isc_result_t result = ISC_R_SUCCESS;

        dev->ev_sender = task;

        set_dev_address(address, sock, dev);
        if (pktinfo != NULL) {
                dev->attributes |= ISC_SOCKEVENTATTR_PKTINFO;
                dev->pktinfo = *pktinfo;

                if (!isc_sockaddr_issitelocal(&dev->address) &&
                    !isc_sockaddr_islinklocal(&dev->address)) {
                        socket_log(sock, NULL, TRACE, isc_msgcat,
                                   ISC_MSGSET_SOCKET, ISC_MSG_PKTINFOPROVIDED,
                                   "pktinfo structure provided, ifindex %u "
                                   "(set to 0)", pktinfo->ipi6_ifindex);

                        /*
                         * Set the pktinfo index to 0 here, to let the
                         * kernel decide what interface it should send on.
                         */
                        dev->pktinfo.ipi6_ifindex = 0;
                }
        }

        if (sock->type == isc_sockettype_udp)
                io_state = doio_send(sock, dev);
        else {
                LOCK(&sock->lock);
                have_lock = ISC_TRUE;

                if (ISC_LIST_EMPTY(sock->send_list))
                        io_state = doio_send(sock, dev);
                else
                        io_state = DOIO_SOFT;
        }

        switch (io_state) {
        case DOIO_SOFT:
                /*
                 * We couldn't send all or part of the request right now, so
                 * queue it unless ISC_SOCKFLAG_NORETRY is set.
                 */
                if ((flags & ISC_SOCKFLAG_NORETRY) == 0) {
                        isc_task_attach(task, &ntask);
                        dev->attributes |= ISC_SOCKEVENTATTR_ATTACHED;

                        if (!have_lock) {
                                LOCK(&sock->lock);
                                have_lock = ISC_TRUE;
                        }

                        /*
                         * Enqueue the request.  If the socket was previously
                         * not being watched, poke the watcher to start
                         * paying attention to it.
                         */
                        if (ISC_LIST_EMPTY(sock->send_list) &&
                            !sock->pending_send)
                                select_poke(sock->manager, sock->fd,
                                            SELECT_POKE_WRITE);
                        ISC_LIST_ENQUEUE(sock->send_list, dev, ev_link);

                        socket_log(sock, NULL, EVENT, NULL, 0, 0,
                                   "socket_send: event %p -> task %p",
                                   dev, ntask);

                        if ((flags & ISC_SOCKFLAG_IMMEDIATE) != 0)
                                result = ISC_R_INPROGRESS;
                        break;
                }

        case DOIO_HARD:
        case DOIO_SUCCESS:
                if ((flags & ISC_SOCKFLAG_IMMEDIATE) == 0)
                        send_senddone_event(sock, &dev);
                break;
        }

        if (have_lock)
                UNLOCK(&sock->lock);

        return (result);
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_send(isc_socket_t *sock, isc_region_t *region,
                 isc_task_t *task, isc_taskaction_t action, void *arg)
{
        /*
         * REQUIRE() checking is performed in isc_socket_sendto().
         */
        return (isc__socket_sendto(sock, region, task, action, arg, NULL,
                                   NULL));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendto(isc_socket_t *sock0, isc_region_t *region,
                   isc_task_t *task, isc_taskaction_t action, void *arg,
                   isc_sockaddr_t *address, struct in6_pktinfo *pktinfo)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_socketevent_t *dev;
        isc__socketmgr_t *manager;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(region != NULL);
        REQUIRE(task != NULL);
        REQUIRE(action != NULL);

        manager = sock->manager;
        REQUIRE(VALID_MANAGER(manager));

        INSIST(sock->bound);

        dev = allocate_socketevent(sock, ISC_SOCKEVENT_SENDDONE, action, arg);
        if (dev == NULL)
                return (ISC_R_NOMEMORY);

        dev->region = *region;

        return (socket_send(sock, dev, task, address, pktinfo, 0));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendv(isc_socket_t *sock, isc_bufferlist_t *buflist,
                  isc_task_t *task, isc_taskaction_t action, void *arg)
{
        return (isc__socket_sendtov2(sock, buflist, task, action, arg, NULL,
                                     NULL, 0));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendtov(isc_socket_t *sock, isc_bufferlist_t *buflist,
                    isc_task_t *task, isc_taskaction_t action, void *arg,
                    isc_sockaddr_t *address, struct in6_pktinfo *pktinfo)
{
        return (isc__socket_sendtov2(sock, buflist, task, action, arg, address,
                                     pktinfo, 0));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendtov2(isc_socket_t *sock0, isc_bufferlist_t *buflist,
                     isc_task_t *task, isc_taskaction_t action, void *arg,
                     isc_sockaddr_t *address, struct in6_pktinfo *pktinfo,
                     unsigned int flags)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_socketevent_t *dev;
        isc__socketmgr_t *manager;
        unsigned int iocount;
        isc_buffer_t *buffer;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(buflist != NULL);
        REQUIRE(!ISC_LIST_EMPTY(*buflist));
        REQUIRE(task != NULL);
        REQUIRE(action != NULL);

        manager = sock->manager;
        REQUIRE(VALID_MANAGER(manager));

        iocount = isc_bufferlist_usedcount(buflist);
        REQUIRE(iocount > 0);

        dev = allocate_socketevent(sock, ISC_SOCKEVENT_SENDDONE, action, arg);
        if (dev == NULL)
                return (ISC_R_NOMEMORY);

        /*
         * Move each buffer from the passed in list to our internal one.
         */
        buffer = ISC_LIST_HEAD(*buflist);
        while (buffer != NULL) {
                ISC_LIST_DEQUEUE(*buflist, buffer, link);
                ISC_LIST_ENQUEUE(dev->bufferlist, buffer, link);
                buffer = ISC_LIST_HEAD(*buflist);
        }

        return (socket_send(sock, dev, task, address, pktinfo, flags));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_sendto2(isc_socket_t *sock0, isc_region_t *region,
                    isc_task_t *task,
                    isc_sockaddr_t *address, struct in6_pktinfo *pktinfo,
                    isc_socketevent_t *event, unsigned int flags)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE((flags & ~(ISC_SOCKFLAG_IMMEDIATE|ISC_SOCKFLAG_NORETRY)) == 0);
        if ((flags & ISC_SOCKFLAG_NORETRY) != 0)
                REQUIRE(sock->type == isc_sockettype_udp);
        event->ev_sender = sock;
        event->result = ISC_R_UNSET;
        ISC_LIST_INIT(event->bufferlist);
        event->region = *region;
        event->n = 0;
        event->offset = 0;
        event->attributes = 0;

        return (socket_send(sock, event, task, address, pktinfo, flags));
}

ISC_SOCKETFUNC_SCOPE void
isc__socket_cleanunix(isc_sockaddr_t *sockaddr, isc_boolean_t active) {
#ifdef ISC_PLATFORM_HAVESYSUNH
        int s;
        struct stat sb;
        char strbuf[ISC_STRERRORSIZE];

        if (sockaddr->type.sa.sa_family != AF_UNIX)
                return;

#ifndef S_ISSOCK
#if defined(S_IFMT) && defined(S_IFSOCK)
#define S_ISSOCK(mode) ((mode & S_IFMT)==S_IFSOCK)
#elif defined(_S_IFMT) && defined(S_IFSOCK)
#define S_ISSOCK(mode) ((mode & _S_IFMT)==S_IFSOCK)
#endif
#endif

#ifndef S_ISFIFO
#if defined(S_IFMT) && defined(S_IFIFO)
#define S_ISFIFO(mode) ((mode & S_IFMT)==S_IFIFO)
#elif defined(_S_IFMT) && defined(S_IFIFO)
#define S_ISFIFO(mode) ((mode & _S_IFMT)==S_IFIFO)
#endif
#endif

#if !defined(S_ISFIFO) && !defined(S_ISSOCK)
#error You need to define S_ISFIFO and S_ISSOCK as appropriate for your platform.  See <sys/stat.h>.
#endif

#ifndef S_ISFIFO
#define S_ISFIFO(mode) 0
#endif

#ifndef S_ISSOCK
#define S_ISSOCK(mode) 0
#endif

        if (active) {
                if (stat(sockaddr->type.sunix.sun_path, &sb) < 0) {
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                                      "isc_socket_cleanunix: stat(%s): %s",
                                      sockaddr->type.sunix.sun_path, strbuf);
                        return;
                }
                if (!(S_ISSOCK(sb.st_mode) || S_ISFIFO(sb.st_mode))) {
                        isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                                      "isc_socket_cleanunix: %s: not a socket",
                                      sockaddr->type.sunix.sun_path);
                        return;
                }
                if (unlink(sockaddr->type.sunix.sun_path) < 0) {
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                                      "isc_socket_cleanunix: unlink(%s): %s",
                                      sockaddr->type.sunix.sun_path, strbuf);
                }
                return;
        }

        s = socket(AF_UNIX, SOCK_STREAM, 0);
        if (s < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                              ISC_LOGMODULE_SOCKET, ISC_LOG_WARNING,
                              "isc_socket_cleanunix: socket(%s): %s",
                              sockaddr->type.sunix.sun_path, strbuf);
                return;
        }

        if (stat(sockaddr->type.sunix.sun_path, &sb) < 0) {
                switch (errno) {
                case ENOENT:    /* We exited cleanly last time */
                        break;
                default:
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                      ISC_LOGMODULE_SOCKET, ISC_LOG_WARNING,
                                      "isc_socket_cleanunix: stat(%s): %s",
                                      sockaddr->type.sunix.sun_path, strbuf);
                        break;
                }
                goto cleanup;
        }

        if (!(S_ISSOCK(sb.st_mode) || S_ISFIFO(sb.st_mode))) {
                isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                              ISC_LOGMODULE_SOCKET, ISC_LOG_WARNING,
                              "isc_socket_cleanunix: %s: not a socket",
                              sockaddr->type.sunix.sun_path);
                goto cleanup;
        }

        if (connect(s, (struct sockaddr *)&sockaddr->type.sunix,
                    sizeof(sockaddr->type.sunix)) < 0) {
                switch (errno) {
                case ECONNREFUSED:
                case ECONNRESET:
                        if (unlink(sockaddr->type.sunix.sun_path) < 0) {
                                isc__strerror(errno, strbuf, sizeof(strbuf));
                                isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                              ISC_LOGMODULE_SOCKET,
                                              ISC_LOG_WARNING,
                                              "isc_socket_cleanunix: "
                                              "unlink(%s): %s",
                                              sockaddr->type.sunix.sun_path,
                                              strbuf);
                        }
                        break;
                default:
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                                      ISC_LOGMODULE_SOCKET, ISC_LOG_WARNING,
                                      "isc_socket_cleanunix: connect(%s): %s",
                                      sockaddr->type.sunix.sun_path, strbuf);
                        break;
                }
        }
 cleanup:
        close(s);
#else
        UNUSED(sockaddr);
        UNUSED(active);
#endif
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_permunix(isc_sockaddr_t *sockaddr, isc_uint32_t perm,
                    isc_uint32_t owner, isc_uint32_t group)
{
#ifdef ISC_PLATFORM_HAVESYSUNH
        isc_result_t result = ISC_R_SUCCESS;
        char strbuf[ISC_STRERRORSIZE];
        char path[sizeof(sockaddr->type.sunix.sun_path)];
#ifdef NEED_SECURE_DIRECTORY
        char *slash;
#endif

        REQUIRE(sockaddr->type.sa.sa_family == AF_UNIX);
        INSIST(strlen(sockaddr->type.sunix.sun_path) < sizeof(path));
        strcpy(path, sockaddr->type.sunix.sun_path);

#ifdef NEED_SECURE_DIRECTORY
        slash = strrchr(path, '/');
        if (slash != NULL) {
                if (slash != path)
                        *slash = '\0';
                else
                        strcpy(path, "/");
        } else
                strcpy(path, ".");
#endif

        if (chmod(path, perm) < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                              ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                              "isc_socket_permunix: chmod(%s, %d): %s",
                              path, perm, strbuf);
                result = ISC_R_FAILURE;
        }
        if (chown(path, owner, group) < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                              ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
                              "isc_socket_permunix: chown(%s, %d, %d): %s",
                              path, owner, group,
                              strbuf);
                result = ISC_R_FAILURE;
        }
        return (result);
#else
        UNUSED(sockaddr);
        UNUSED(perm);
        UNUSED(owner);
        UNUSED(group);
        return (ISC_R_NOTIMPLEMENTED);
#endif
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_bind(isc_socket_t *sock0, isc_sockaddr_t *sockaddr,
                 unsigned int options) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
        char strbuf[ISC_STRERRORSIZE];
        int on = 1;

        REQUIRE(VALID_SOCKET(sock));

        LOCK(&sock->lock);

        INSIST(!sock->bound);
        INSIST(!sock->dupped);

        if (sock->pf != sockaddr->type.sa.sa_family) {
                UNLOCK(&sock->lock);
                return (ISC_R_FAMILYMISMATCH);
        }

        /*
         * Only set SO_REUSEADDR when we want a specific port.
         */
#ifdef AF_UNIX
        if (sock->pf == AF_UNIX)
                goto bind_socket;
#endif
        if ((options & ISC_SOCKET_REUSEADDRESS) != 0 &&
            isc_sockaddr_getport(sockaddr) != (in_port_t)0 &&
            setsockopt(sock->fd, SOL_SOCKET, SO_REUSEADDR, (void *)&on,
                       sizeof(on)) < 0) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "setsockopt(%d) %s", sock->fd,
                                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
                                                ISC_MSG_FAILED, "failed"));
                /* Press on... */
        }
#ifdef AF_UNIX
 bind_socket:
#endif
        if (bind(sock->fd, &sockaddr->type.sa, sockaddr->length) < 0) {
                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_BINDFAIL]);

                UNLOCK(&sock->lock);
                switch (errno) {
                case EACCES:
                        return (ISC_R_NOPERM);
                case EADDRNOTAVAIL:
                        return (ISC_R_ADDRNOTAVAIL);
                case EADDRINUSE:
                        return (ISC_R_ADDRINUSE);
                case EINVAL:
                        return (ISC_R_BOUND);
                default:
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        UNEXPECTED_ERROR(__FILE__, __LINE__, "bind: %s",
                                         strbuf);
                        return (ISC_R_UNEXPECTED);
                }
        }

        socket_log(sock, sockaddr, TRACE,
                   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_BOUND, "bound");
        sock->bound = 1;

        UNLOCK(&sock->lock);
        return (ISC_R_SUCCESS);
}

/*
 * Enable this only for specific OS versions, and only when they have repaired
 * their problems with it.  Until then, this is is broken and needs to be
 * diabled by default.  See RT22589 for details.
 */
#undef ENABLE_ACCEPTFILTER

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_filter(isc_socket_t *sock0, const char *filter) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
#if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER)
        char strbuf[ISC_STRERRORSIZE];
        struct accept_filter_arg afa;
#else
        UNUSED(sock);
        UNUSED(filter);
#endif

        REQUIRE(VALID_SOCKET(sock));

#if defined(SO_ACCEPTFILTER) && defined(ENABLE_ACCEPTFILTER)
        bzero(&afa, sizeof(afa));
        strncpy(afa.af_name, filter, sizeof(afa.af_name));
        if (setsockopt(sock->fd, SOL_SOCKET, SO_ACCEPTFILTER,
                         &afa, sizeof(afa)) == -1) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                socket_log(sock, NULL, CREATION, isc_msgcat, ISC_MSGSET_SOCKET,
                           ISC_MSG_FILTER, "setsockopt(SO_ACCEPTFILTER): %s",
                           strbuf);
                return (ISC_R_FAILURE);
        }
        return (ISC_R_SUCCESS);
#else
        return (ISC_R_NOTIMPLEMENTED);
#endif
}

/*
 * Set up to listen on a given socket.  We do this by creating an internal
 * event that will be dispatched when the socket has read activity.  The
 * watcher will send the internal event to the task when there is a new
 * connection.
 *
 * Unlike in read, we don't preallocate a done event here.  Every time there
 * is a new connection we'll have to allocate a new one anyway, so we might
 * as well keep things simple rather than having to track them.
 */
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_listen(isc_socket_t *sock0, unsigned int backlog) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
        char strbuf[ISC_STRERRORSIZE];

        REQUIRE(VALID_SOCKET(sock));

        LOCK(&sock->lock);

        REQUIRE(!sock->listener);
        REQUIRE(sock->bound);
        REQUIRE(sock->type == isc_sockettype_tcp ||
                sock->type == isc_sockettype_unix);

        if (backlog == 0)
                backlog = SOMAXCONN;

        if (listen(sock->fd, (int)backlog) < 0) {
                UNLOCK(&sock->lock);
                isc__strerror(errno, strbuf, sizeof(strbuf));

                UNEXPECTED_ERROR(__FILE__, __LINE__, "listen: %s", strbuf);

                return (ISC_R_UNEXPECTED);
        }

        sock->listener = 1;

        UNLOCK(&sock->lock);
        return (ISC_R_SUCCESS);
}

/*
 * This should try to do aggressive accept() XXXMLG
 */
ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_accept(isc_socket_t *sock0,
                  isc_task_t *task, isc_taskaction_t action, void *arg)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_socket_newconnev_t *dev;
        isc__socketmgr_t *manager;
        isc_task_t *ntask = NULL;
        isc__socket_t *nsock;
        isc_result_t result;
        isc_boolean_t do_poke = ISC_FALSE;

        REQUIRE(VALID_SOCKET(sock));
        manager = sock->manager;
        REQUIRE(VALID_MANAGER(manager));

        LOCK(&sock->lock);

        REQUIRE(sock->listener);

        /*
         * Sender field is overloaded here with the task we will be sending
         * this event to.  Just before the actual event is delivered the
         * actual ev_sender will be touched up to be the socket.
         */
        dev = (isc_socket_newconnev_t *)
                isc_event_allocate(manager->mctx, task, ISC_SOCKEVENT_NEWCONN,
                                   action, arg, sizeof(*dev));
        if (dev == NULL) {
                UNLOCK(&sock->lock);
                return (ISC_R_NOMEMORY);
        }
        ISC_LINK_INIT(dev, ev_link);

        result = allocate_socket(manager, sock->type, &nsock);
        if (result != ISC_R_SUCCESS) {
                isc_event_free(ISC_EVENT_PTR(&dev));
                UNLOCK(&sock->lock);
                return (result);
        }

        /*
         * Attach to socket and to task.
         */
        isc_task_attach(task, &ntask);
        if (isc_task_exiting(ntask)) {
                free_socket(&nsock);
                isc_task_detach(&ntask);
                isc_event_free(ISC_EVENT_PTR(&dev));
                UNLOCK(&sock->lock);
                return (ISC_R_SHUTTINGDOWN);
        }
        nsock->references++;
        nsock->statsindex = sock->statsindex;

        dev->ev_sender = ntask;
        dev->newsocket = (isc_socket_t *)nsock;

        /*
         * Poke watcher here.  We still have the socket locked, so there
         * is no race condition.  We will keep the lock for such a short
         * bit of time waking it up now or later won't matter all that much.
         */
        if (ISC_LIST_EMPTY(sock->accept_list))
                do_poke = ISC_TRUE;

        ISC_LIST_ENQUEUE(sock->accept_list, dev, ev_link);

        if (do_poke)
                select_poke(manager, sock->fd, SELECT_POKE_ACCEPT);

        UNLOCK(&sock->lock);
        return (ISC_R_SUCCESS);
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_connect(isc_socket_t *sock0, isc_sockaddr_t *addr,
                   isc_task_t *task, isc_taskaction_t action, void *arg)
{
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_socket_connev_t *dev;
        isc_task_t *ntask = NULL;
        isc__socketmgr_t *manager;
        int cc;
        char strbuf[ISC_STRERRORSIZE];
        char addrbuf[ISC_SOCKADDR_FORMATSIZE];

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(addr != NULL);
        REQUIRE(task != NULL);
        REQUIRE(action != NULL);

        manager = sock->manager;
        REQUIRE(VALID_MANAGER(manager));
        REQUIRE(addr != NULL);

        if (isc_sockaddr_ismulticast(addr))
                return (ISC_R_MULTICAST);

        LOCK(&sock->lock);

        REQUIRE(!sock->connecting);

        dev = (isc_socket_connev_t *)isc_event_allocate(manager->mctx, sock,
                                                        ISC_SOCKEVENT_CONNECT,
                                                        action, arg,
                                                        sizeof(*dev));
        if (dev == NULL) {
                UNLOCK(&sock->lock);
                return (ISC_R_NOMEMORY);
        }
        ISC_LINK_INIT(dev, ev_link);

        /*
         * Try to do the connect right away, as there can be only one
         * outstanding, and it might happen to complete.
         */
        sock->peer_address = *addr;
        cc = connect(sock->fd, &addr->type.sa, addr->length);
        if (cc < 0) {
                /*
                 * HP-UX "fails" to connect a UDP socket and sets errno to
                 * EINPROGRESS if it's non-blocking.  We'd rather regard this as
                 * a success and let the user detect it if it's really an error
                 * at the time of sending a packet on the socket.
                 */
                if (sock->type == isc_sockettype_udp && errno == EINPROGRESS) {
                        cc = 0;
                        goto success;
                }
                if (SOFT_ERROR(errno) || errno == EINPROGRESS)
                        goto queue;

                switch (errno) {
#define ERROR_MATCH(a, b) case a: dev->result = b; goto err_exit;
                        ERROR_MATCH(EACCES, ISC_R_NOPERM);
                        ERROR_MATCH(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
                        ERROR_MATCH(EAFNOSUPPORT, ISC_R_ADDRNOTAVAIL);
                        ERROR_MATCH(ECONNREFUSED, ISC_R_CONNREFUSED);
                        ERROR_MATCH(EHOSTUNREACH, ISC_R_HOSTUNREACH);
#ifdef EHOSTDOWN
                        ERROR_MATCH(EHOSTDOWN, ISC_R_HOSTUNREACH);
#endif
                        ERROR_MATCH(ENETUNREACH, ISC_R_NETUNREACH);
                        ERROR_MATCH(ENOBUFS, ISC_R_NORESOURCES);
                        ERROR_MATCH(EPERM, ISC_R_HOSTUNREACH);
                        ERROR_MATCH(EPIPE, ISC_R_NOTCONNECTED);
                        ERROR_MATCH(ECONNRESET, ISC_R_CONNECTIONRESET);
#undef ERROR_MATCH
                }

                sock->connected = 0;

                isc__strerror(errno, strbuf, sizeof(strbuf));
                isc_sockaddr_format(addr, addrbuf, sizeof(addrbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__, "connect(%s) %d/%s",
                                 addrbuf, errno, strbuf);

                UNLOCK(&sock->lock);
                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_CONNECTFAIL]);
                isc_event_free(ISC_EVENT_PTR(&dev));
                return (ISC_R_UNEXPECTED);

        err_exit:
                sock->connected = 0;
                isc_task_send(task, ISC_EVENT_PTR(&dev));

                UNLOCK(&sock->lock);
                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_CONNECTFAIL]);
                return (ISC_R_SUCCESS);
        }

        /*
         * If connect completed, fire off the done event.
         */
 success:
        if (cc == 0) {
                sock->connected = 1;
                sock->bound = 1;
                dev->result = ISC_R_SUCCESS;
                isc_task_send(task, ISC_EVENT_PTR(&dev));

                UNLOCK(&sock->lock);

                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_CONNECT]);

                return (ISC_R_SUCCESS);
        }

 queue:

        /*
         * Attach to task.
         */
        isc_task_attach(task, &ntask);

        sock->connecting = 1;

        dev->ev_sender = ntask;

        /*
         * Poke watcher here.  We still have the socket locked, so there
         * is no race condition.  We will keep the lock for such a short
         * bit of time waking it up now or later won't matter all that much.
         */
        if (sock->connect_ev == NULL)
                select_poke(manager, sock->fd, SELECT_POKE_CONNECT);

        sock->connect_ev = dev;

        UNLOCK(&sock->lock);
        return (ISC_R_SUCCESS);
}

/*
 * Called when a socket with a pending connect() finishes.
 */
static void
internal_connect(isc_task_t *me, isc_event_t *ev) {
        isc__socket_t *sock;
        isc_socket_connev_t *dev;
        isc_task_t *task;
        int cc;
        ISC_SOCKADDR_LEN_T optlen;
        char strbuf[ISC_STRERRORSIZE];
        char peerbuf[ISC_SOCKADDR_FORMATSIZE];

        UNUSED(me);
        INSIST(ev->ev_type == ISC_SOCKEVENT_INTW);

        sock = ev->ev_sender;
        INSIST(VALID_SOCKET(sock));

        LOCK(&sock->lock);

        /*
         * When the internal event was sent the reference count was bumped
         * to keep the socket around for us.  Decrement the count here.
         */
        INSIST(sock->references > 0);
        sock->references--;
        if (sock->references == 0) {
                UNLOCK(&sock->lock);
                destroy(&sock);
                return;
        }

        /*
         * Has this event been canceled?
         */
        dev = sock->connect_ev;
        if (dev == NULL) {
                INSIST(!sock->connecting);
                UNLOCK(&sock->lock);
                return;
        }

        INSIST(sock->connecting);
        sock->connecting = 0;

        /*
         * Get any possible error status here.
         */
        optlen = sizeof(cc);
        if (getsockopt(sock->fd, SOL_SOCKET, SO_ERROR,
                       (void *)&cc, (void *)&optlen) < 0)
                cc = errno;
        else
                errno = cc;

        if (errno != 0) {
                /*
                 * If the error is EAGAIN, just re-select on this
                 * fd and pretend nothing strange happened.
                 */
                if (SOFT_ERROR(errno) || errno == EINPROGRESS) {
                        sock->connecting = 1;
                        select_poke(sock->manager, sock->fd,
                                    SELECT_POKE_CONNECT);
                        UNLOCK(&sock->lock);

                        return;
                }

                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_CONNECTFAIL]);

                /*
                 * Translate other errors into ISC_R_* flavors.
                 */
                switch (errno) {
#define ERROR_MATCH(a, b) case a: dev->result = b; break;
                        ERROR_MATCH(EACCES, ISC_R_NOPERM);
                        ERROR_MATCH(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
                        ERROR_MATCH(EAFNOSUPPORT, ISC_R_ADDRNOTAVAIL);
                        ERROR_MATCH(ECONNREFUSED, ISC_R_CONNREFUSED);
                        ERROR_MATCH(EHOSTUNREACH, ISC_R_HOSTUNREACH);
#ifdef EHOSTDOWN
                        ERROR_MATCH(EHOSTDOWN, ISC_R_HOSTUNREACH);
#endif
                        ERROR_MATCH(ENETUNREACH, ISC_R_NETUNREACH);
                        ERROR_MATCH(ENOBUFS, ISC_R_NORESOURCES);
                        ERROR_MATCH(EPERM, ISC_R_HOSTUNREACH);
                        ERROR_MATCH(EPIPE, ISC_R_NOTCONNECTED);
                        ERROR_MATCH(ETIMEDOUT, ISC_R_TIMEDOUT);
                        ERROR_MATCH(ECONNRESET, ISC_R_CONNECTIONRESET);
#undef ERROR_MATCH
                default:
                        dev->result = ISC_R_UNEXPECTED;
                        isc_sockaddr_format(&sock->peer_address, peerbuf,
                                            sizeof(peerbuf));
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "internal_connect: connect(%s) %s",
                                         peerbuf, strbuf);
                }
        } else {
                inc_stats(sock->manager->stats,
                          sock->statsindex[STATID_CONNECT]);
                dev->result = ISC_R_SUCCESS;
                sock->connected = 1;
                sock->bound = 1;
        }

        sock->connect_ev = NULL;

        UNLOCK(&sock->lock);

        task = dev->ev_sender;
        dev->ev_sender = sock;
        isc_task_sendanddetach(&task, ISC_EVENT_PTR(&dev));
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_getpeername(isc_socket_t *sock0, isc_sockaddr_t *addressp) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_result_t result;

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(addressp != NULL);

        LOCK(&sock->lock);

        if (sock->connected) {
                *addressp = sock->peer_address;
                result = ISC_R_SUCCESS;
        } else {
                result = ISC_R_NOTCONNECTED;
        }

        UNLOCK(&sock->lock);

        return (result);
}

ISC_SOCKETFUNC_SCOPE isc_result_t
isc__socket_getsockname(isc_socket_t *sock0, isc_sockaddr_t *addressp) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
        ISC_SOCKADDR_LEN_T len;
        isc_result_t result;
        char strbuf[ISC_STRERRORSIZE];

        REQUIRE(VALID_SOCKET(sock));
        REQUIRE(addressp != NULL);

        LOCK(&sock->lock);

        if (!sock->bound) {
                result = ISC_R_NOTBOUND;
                goto out;
        }

        result = ISC_R_SUCCESS;

        len = sizeof(addressp->type);
        if (getsockname(sock->fd, &addressp->type.sa, (void *)&len) < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__, "getsockname: %s",
                                 strbuf);
                result = ISC_R_UNEXPECTED;
                goto out;
        }
        addressp->length = (unsigned int)len;

 out:
        UNLOCK(&sock->lock);

        return (result);
}

/*
 * Run through the list of events on this socket, and cancel the ones
 * queued for task "task" of type "how".  "how" is a bitmask.
 */
ISC_SOCKETFUNC_SCOPE void
isc__socket_cancel(isc_socket_t *sock0, isc_task_t *task, unsigned int how) {
        isc__socket_t *sock = (isc__socket_t *)sock0;

        REQUIRE(VALID_SOCKET(sock));

        /*
         * Quick exit if there is nothing to do.  Don't even bother locking
         * in this case.
         */
        if (how == 0)
                return;

        LOCK(&sock->lock);

        /*
         * All of these do the same thing, more or less.
         * Each will:
         *      o If the internal event is marked as "posted" try to
         *        remove it from the task's queue.  If this fails, mark it
         *        as canceled instead, and let the task clean it up later.
         *      o For each I/O request for that task of that type, post
         *        its done event with status of "ISC_R_CANCELED".
         *      o Reset any state needed.
         */
        if (((how & ISC_SOCKCANCEL_RECV) == ISC_SOCKCANCEL_RECV)
            && !ISC_LIST_EMPTY(sock->recv_list)) {
                isc_socketevent_t      *dev;
                isc_socketevent_t      *next;
                isc_task_t             *current_task;

                dev = ISC_LIST_HEAD(sock->recv_list);

                while (dev != NULL) {
                        current_task = dev->ev_sender;
                        next = ISC_LIST_NEXT(dev, ev_link);

                        if ((task == NULL) || (task == current_task)) {
                                dev->result = ISC_R_CANCELED;
                                send_recvdone_event(sock, &dev);
                        }
                        dev = next;
                }
        }

        if (((how & ISC_SOCKCANCEL_SEND) == ISC_SOCKCANCEL_SEND)
            && !ISC_LIST_EMPTY(sock->send_list)) {
                isc_socketevent_t      *dev;
                isc_socketevent_t      *next;
                isc_task_t             *current_task;

                dev = ISC_LIST_HEAD(sock->send_list);

                while (dev != NULL) {
                        current_task = dev->ev_sender;
                        next = ISC_LIST_NEXT(dev, ev_link);

                        if ((task == NULL) || (task == current_task)) {
                                dev->result = ISC_R_CANCELED;
                                send_senddone_event(sock, &dev);
                        }
                        dev = next;
                }
        }

        if (((how & ISC_SOCKCANCEL_ACCEPT) == ISC_SOCKCANCEL_ACCEPT)
            && !ISC_LIST_EMPTY(sock->accept_list)) {
                isc_socket_newconnev_t *dev;
                isc_socket_newconnev_t *next;
                isc_task_t             *current_task;

                dev = ISC_LIST_HEAD(sock->accept_list);
                while (dev != NULL) {
                        current_task = dev->ev_sender;
                        next = ISC_LIST_NEXT(dev, ev_link);

                        if ((task == NULL) || (task == current_task)) {

                                ISC_LIST_UNLINK(sock->accept_list, dev,
                                                ev_link);

                                NEWCONNSOCK(dev)->references--;
                                free_socket((isc__socket_t **)&dev->newsocket);

                                dev->result = ISC_R_CANCELED;
                                dev->ev_sender = sock;
                                isc_task_sendanddetach(&current_task,
                                                       ISC_EVENT_PTR(&dev));
                        }

                        dev = next;
                }
        }

        /*
         * Connecting is not a list.
         */
        if (((how & ISC_SOCKCANCEL_CONNECT) == ISC_SOCKCANCEL_CONNECT)
            && sock->connect_ev != NULL) {
                isc_socket_connev_t    *dev;
                isc_task_t             *current_task;

                INSIST(sock->connecting);
                sock->connecting = 0;

                dev = sock->connect_ev;
                current_task = dev->ev_sender;

                if ((task == NULL) || (task == current_task)) {
                        sock->connect_ev = NULL;

                        dev->result = ISC_R_CANCELED;
                        dev->ev_sender = sock;
                        isc_task_sendanddetach(&current_task,
                                               ISC_EVENT_PTR(&dev));
                }
        }

        UNLOCK(&sock->lock);
}

ISC_SOCKETFUNC_SCOPE isc_sockettype_t
isc__socket_gettype(isc_socket_t *sock0) {
        isc__socket_t *sock = (isc__socket_t *)sock0;

        REQUIRE(VALID_SOCKET(sock));

        return (sock->type);
}

ISC_SOCKETFUNC_SCOPE isc_boolean_t
isc__socket_isbound(isc_socket_t *sock0) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
        isc_boolean_t val;

        REQUIRE(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        val = ((sock->bound) ? ISC_TRUE : ISC_FALSE);
        UNLOCK(&sock->lock);

        return (val);
}

ISC_SOCKETFUNC_SCOPE void
isc__socket_ipv6only(isc_socket_t *sock0, isc_boolean_t yes) {
        isc__socket_t *sock = (isc__socket_t *)sock0;
#if defined(IPV6_V6ONLY)
        int onoff = yes ? 1 : 0;
#else
        UNUSED(yes);
        UNUSED(sock);
#endif

        REQUIRE(VALID_SOCKET(sock));
        INSIST(!sock->dupped);

#ifdef IPV6_V6ONLY
        if (sock->pf == AF_INET6) {
                if (setsockopt(sock->fd, IPPROTO_IPV6, IPV6_V6ONLY,
                               (void *)&onoff, sizeof(int)) < 0) {
                        char strbuf[ISC_STRERRORSIZE];
                        isc__strerror(errno, strbuf, sizeof(strbuf));
                        UNEXPECTED_ERROR(__FILE__, __LINE__,
                                         "setsockopt(%d, IPV6_V6ONLY) "
                                         "%s: %s", sock->fd,
                                         isc_msgcat_get(isc_msgcat,
                                                        ISC_MSGSET_GENERAL,
                                                        ISC_MSG_FAILED,
                                                        "failed"),
                                         strbuf);
                }
        }
        FIX_IPV6_RECVPKTINFO(sock);     /* AIX */
#endif
}

#ifndef USE_WATCHER_THREAD
/*
 * In our assumed scenario, we can simply use a single static object.
 * XXX: this is not true if the application uses multiple threads with
 *      'multi-context' mode.  Fixing this is a future TODO item.
 */
static isc_socketwait_t swait_private;

int
isc__socketmgr_waitevents(isc_socketmgr_t *manager0, struct timeval *tvp,
                          isc_socketwait_t **swaitp)
{
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;
        int n;
#ifdef USE_KQUEUE
        struct timespec ts, *tsp;
#endif
#ifdef USE_EPOLL
        int timeout;
#endif
#ifdef USE_DEVPOLL
        isc_result_t result;
        int pass;
        struct dvpoll dvp;
#endif

        REQUIRE(swaitp != NULL && *swaitp == NULL);

#ifdef USE_SHARED_MANAGER
        if (manager == NULL)
                manager = socketmgr;
#endif
        if (manager == NULL)
                return (0);

#ifdef USE_KQUEUE
        if (tvp != NULL) {
                ts.tv_sec = tvp->tv_sec;
                ts.tv_nsec = tvp->tv_usec * 1000;
                tsp = &ts;
        } else
                tsp = NULL;
        swait_private.nevents = kevent(manager->kqueue_fd, NULL, 0,
                                       manager->events, manager->nevents,
                                       tsp);
        n = swait_private.nevents;
#elif defined(USE_EPOLL)
        if (tvp != NULL)
                timeout = tvp->tv_sec * 1000 + (tvp->tv_usec + 999) / 1000;
        else
                timeout = -1;
        swait_private.nevents = epoll_wait(manager->epoll_fd,
                                           manager->events,
                                           manager->nevents, timeout);
        n = swait_private.nevents;
#elif defined(USE_DEVPOLL)
        /*
         * Re-probe every thousand calls.
         */
        if (manager->calls++ > 1000U) {
                result = isc_resource_getcurlimit(isc_resource_openfiles,
                                                  &manager->open_max);
                if (result != ISC_R_SUCCESS)
                        manager->open_max = 64;
                manager->calls = 0;
        }
        for (pass = 0; pass < 2; pass++) {
                dvp.dp_fds = manager->events;
                dvp.dp_nfds = manager->nevents;
                if (dvp.dp_nfds >= manager->open_max)
                        dvp.dp_nfds = manager->open_max - 1;
                if (tvp != NULL) {
                        dvp.dp_timeout = tvp->tv_sec * 1000 +
                                (tvp->tv_usec + 999) / 1000;
                } else
                        dvp.dp_timeout = -1;
                n = ioctl(manager->devpoll_fd, DP_POLL, &dvp);
                if (n == -1 && errno == EINVAL) {
                        /*
                         * {OPEN_MAX} may have dropped.  Look
                         * up the current value and try again.
                         */
                        result = isc_resource_getcurlimit(
                                                        isc_resource_openfiles,
                                                        &manager->open_max);
                        if (result != ISC_R_SUCCESS)
                                manager->open_max = 64;
                } else
                        break;
        }
        swait_private.nevents = n;
#elif defined(USE_SELECT)
        memmove(manager->read_fds_copy, manager->read_fds, manager->fd_bufsize);
        memmove(manager->write_fds_copy, manager->write_fds,
                manager->fd_bufsize);

        swait_private.readset = manager->read_fds_copy;
        swait_private.writeset = manager->write_fds_copy;
        swait_private.maxfd = manager->maxfd + 1;

        n = select(swait_private.maxfd, swait_private.readset,
                   swait_private.writeset, NULL, tvp);
#endif

        *swaitp = &swait_private;
        return (n);
}

isc_result_t
isc__socketmgr_dispatch(isc_socketmgr_t *manager0, isc_socketwait_t *swait) {
        isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;

        REQUIRE(swait == &swait_private);

#ifdef USE_SHARED_MANAGER
        if (manager == NULL)
                manager = socketmgr;
#endif
        if (manager == NULL)
                return (ISC_R_NOTFOUND);

#if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
        (void)process_fds(manager, manager->events, swait->nevents);
        return (ISC_R_SUCCESS);
#elif defined(USE_SELECT)
        process_fds(manager, swait->maxfd, swait->readset, swait->writeset);
        return (ISC_R_SUCCESS);
#endif
}
#endif /* USE_WATCHER_THREAD */

#ifdef BIND9
void
isc__socket_setname(isc_socket_t *socket0, const char *name, void *tag) {
        isc__socket_t *sock = (isc__socket_t *)socket0;

        /*
         * Name 'sock'.
         */

        REQUIRE(VALID_SOCKET(sock));

        LOCK(&sock->lock);
        memset(sock->name, 0, sizeof(sock->name));
        strncpy(sock->name, name, sizeof(sock->name) - 1);
        sock->tag = tag;
        UNLOCK(&sock->lock);
}

ISC_SOCKETFUNC_SCOPE const char *
isc__socket_getname(isc_socket_t *socket0) {
        isc__socket_t *sock = (isc__socket_t *)socket0;

        return (sock->name);
}

void *
isc__socket_gettag(isc_socket_t *socket0) {
        isc__socket_t *sock = (isc__socket_t *)socket0;

        return (sock->tag);
}
#endif  /* BIND9 */

#ifdef USE_SOCKETIMPREGISTER
isc_result_t
isc__socket_register(void) {
        return (isc_socket_register(isc__socketmgr_create));
}
#endif

ISC_SOCKETFUNC_SCOPE int
isc__socket_getfd(isc_socket_t *socket0) {
        isc__socket_t *sock = (isc__socket_t *)socket0;

        return ((short) sock->fd);
}

#if defined(HAVE_LIBXML2) && defined(BIND9)

static const char *
_socktype(isc_sockettype_t type)
{
        if (type == isc_sockettype_udp)
                return ("udp");
        else if (type == isc_sockettype_tcp)
                return ("tcp");
        else if (type == isc_sockettype_unix)
                return ("unix");
        else if (type == isc_sockettype_fdwatch)
                return ("fdwatch");
        else
                return ("not-initialized");
}

#define TRY0(a) do { xmlrc = (a); if (xmlrc < 0) goto error; } while(0)
ISC_SOCKETFUNC_SCOPE int
isc_socketmgr_renderxml(isc_socketmgr_t *mgr0, xmlTextWriterPtr writer) {
        isc__socketmgr_t *mgr = (isc__socketmgr_t *)mgr0;
        isc__socket_t *sock = NULL;
        char peerbuf[ISC_SOCKADDR_FORMATSIZE];
        isc_sockaddr_t addr;
        ISC_SOCKADDR_LEN_T len;
        int xmlrc;

        LOCK(&mgr->lock);

#ifdef USE_SHARED_MANAGER
        TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "references"));
        TRY0(xmlTextWriterWriteFormatString(writer, "%d", mgr->refs));
        TRY0(xmlTextWriterEndElement(writer));
#endif  /* USE_SHARED_MANAGER */

        TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "sockets"));
        sock = ISC_LIST_HEAD(mgr->socklist);
        while (sock != NULL) {
                LOCK(&sock->lock);
                TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "socket"));

                TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "id"));
                TRY0(xmlTextWriterWriteFormatString(writer, "%p", sock));
                TRY0(xmlTextWriterEndElement(writer));

                if (sock->name[0] != 0) {
                        TRY0(xmlTextWriterStartElement(writer,
                                                       ISC_XMLCHAR "name"));
                        TRY0(xmlTextWriterWriteFormatString(writer, "%s",
                                                            sock->name));
                        TRY0(xmlTextWriterEndElement(writer)); /* name */
                }

                TRY0(xmlTextWriterStartElement(writer,
                                               ISC_XMLCHAR "references"));
                TRY0(xmlTextWriterWriteFormatString(writer, "%d",
                                                    sock->references));
                TRY0(xmlTextWriterEndElement(writer));

                TRY0(xmlTextWriterWriteElement(writer, ISC_XMLCHAR "type",
                                          ISC_XMLCHAR _socktype(sock->type)));

                if (sock->connected) {
                        isc_sockaddr_format(&sock->peer_address, peerbuf,
                                            sizeof(peerbuf));
                        TRY0(xmlTextWriterWriteElement(writer,
                                                  ISC_XMLCHAR "peer-address",
                                                  ISC_XMLCHAR peerbuf));
                }

                len = sizeof(addr);
                if (getsockname(sock->fd, &addr.type.sa, (void *)&len) == 0) {
                        isc_sockaddr_format(&addr, peerbuf, sizeof(peerbuf));
                        TRY0(xmlTextWriterWriteElement(writer,
                                                  ISC_XMLCHAR "local-address",
                                                  ISC_XMLCHAR peerbuf));
                }

                TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "states"));
                if (sock->pending_recv)
                        TRY0(xmlTextWriterWriteElement(writer,
                                                ISC_XMLCHAR "state",
                                                ISC_XMLCHAR "pending-receive"));
                if (sock->pending_send)
                        TRY0(xmlTextWriterWriteElement(writer,
                                                  ISC_XMLCHAR "state",
                                                  ISC_XMLCHAR "pending-send"));
                if (sock->pending_accept)
                        TRY0(xmlTextWriterWriteElement(writer,
                                                 ISC_XMLCHAR "state",
                                                 ISC_XMLCHAR "pending_accept"));
                if (sock->listener)
                        TRY0(xmlTextWriterWriteElement(writer,
                                                       ISC_XMLCHAR "state",
                                                       ISC_XMLCHAR "listener"));
                if (sock->connected)
                        TRY0(xmlTextWriterWriteElement(writer,
                                                     ISC_XMLCHAR "state",
                                                     ISC_XMLCHAR "connected"));
                if (sock->connecting)
                        TRY0(xmlTextWriterWriteElement(writer,
                                                    ISC_XMLCHAR "state",
                                                    ISC_XMLCHAR "connecting"));
                if (sock->bound)
                        TRY0(xmlTextWriterWriteElement(writer,
                                                       ISC_XMLCHAR "state",
                                                       ISC_XMLCHAR "bound"));

                TRY0(xmlTextWriterEndElement(writer)); /* states */

                TRY0(xmlTextWriterEndElement(writer)); /* socket */

                UNLOCK(&sock->lock);
                sock = ISC_LIST_NEXT(sock, link);
        }
        TRY0(xmlTextWriterEndElement(writer)); /* sockets */

 error:
        if (sock != NULL)
                UNLOCK(&sock->lock);

        UNLOCK(&mgr->lock);

        return (xmlrc);
}
#endif /* HAVE_LIBXML2 */