MFV: r342867

[FreeBSD/FreeBSD.git] / sys / kern / uipc_socket.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *      The Regents of the University of California.
 * Copyright (c) 2004 The FreeBSD Foundation
 * Copyright (c) 2004-2008 Robert N. M. Watson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)uipc_socket.c       8.3 (Berkeley) 4/15/94
 */

/*
 * Comments on the socket life cycle:
 *
 * soalloc() sets of socket layer state for a socket, called only by
 * socreate() and sonewconn().  Socket layer private.
 *
 * sodealloc() tears down socket layer state for a socket, called only by
 * sofree() and sonewconn().  Socket layer private.
 *
 * pru_attach() associates protocol layer state with an allocated socket;
 * called only once, may fail, aborting socket allocation.  This is called
 * from socreate() and sonewconn().  Socket layer private.
 *
 * pru_detach() disassociates protocol layer state from an attached socket,
 * and will be called exactly once for sockets in which pru_attach() has
 * been successfully called.  If pru_attach() returned an error,
 * pru_detach() will not be called.  Socket layer private.
 *
 * pru_abort() and pru_close() notify the protocol layer that the last
 * consumer of a socket is starting to tear down the socket, and that the
 * protocol should terminate the connection.  Historically, pru_abort() also
 * detached protocol state from the socket state, but this is no longer the
 * case.
 *
 * socreate() creates a socket and attaches protocol state.  This is a public
 * interface that may be used by socket layer consumers to create new
 * sockets.
 *
 * sonewconn() creates a socket and attaches protocol state.  This is a
 * public interface  that may be used by protocols to create new sockets when
 * a new connection is received and will be available for accept() on a
 * listen socket.
 *
 * soclose() destroys a socket after possibly waiting for it to disconnect.
 * This is a public interface that socket consumers should use to close and
 * release a socket when done with it.
 *
 * soabort() destroys a socket without waiting for it to disconnect (used
 * only for incoming connections that are already partially or fully
 * connected).  This is used internally by the socket layer when clearing
 * listen socket queues (due to overflow or close on the listen socket), but
 * is also a public interface protocols may use to abort connections in
 * their incomplete listen queues should they no longer be required.  Sockets
 * placed in completed connection listen queues should not be aborted for
 * reasons described in the comment above the soclose() implementation.  This
 * is not a general purpose close routine, and except in the specific
 * circumstances described here, should not be used.
 *
 * sofree() will free a socket and its protocol state if all references on
 * the socket have been released, and is the public interface to attempt to
 * free a socket when a reference is removed.  This is a socket layer private
 * interface.
 *
 * NOTE: In addition to socreate() and soclose(), which provide a single
 * socket reference to the consumer to be managed as required, there are two
 * calls to explicitly manage socket references, soref(), and sorele().
 * Currently, these are generally required only when transitioning a socket
 * from a listen queue to a file descriptor, in order to prevent garbage
 * collection of the socket at an untimely moment.  For a number of reasons,
 * these interfaces are not preferred, and should be avoided.
 *
 * NOTE: With regard to VNETs the general rule is that callers do not set
 * curvnet. Exceptions to this rule include soabort(), sodisconnect(),
 * sofree() (and with that sorele(), sotryfree()), as well as sonewconn()
 * and sorflush(), which are usually called from a pre-set VNET context.
 * sopoll() currently does not need a VNET context to be set.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_sctp.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mac.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/domain.h>
#include <sys/file.h>                   /* for struct knote */
#include <sys/hhook.h>
#include <sys/kernel.h>
#include <sys/khelp.h>
#include <sys/event.h>
#include <sys/eventhandler.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/resourcevar.h>
#include <net/route.h>
#include <sys/signalvar.h>
#include <sys/stat.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#include <sys/uio.h>
#include <sys/jail.h>
#include <sys/syslog.h>
#include <netinet/in.h>

#include <net/vnet.h>

#include <security/mac/mac_framework.h>

#include <vm/uma.h>

#ifdef COMPAT_FREEBSD32
#include <sys/mount.h>
#include <sys/sysent.h>
#include <compat/freebsd32/freebsd32.h>
#endif

static int      soreceive_rcvoob(struct socket *so, struct uio *uio,
                    int flags);
static void     so_rdknl_lock(void *);
static void     so_rdknl_unlock(void *);
static void     so_rdknl_assert_locked(void *);
static void     so_rdknl_assert_unlocked(void *);
static void     so_wrknl_lock(void *);
static void     so_wrknl_unlock(void *);
static void     so_wrknl_assert_locked(void *);
static void     so_wrknl_assert_unlocked(void *);

static void     filt_sordetach(struct knote *kn);
static int      filt_soread(struct knote *kn, long hint);
static void     filt_sowdetach(struct knote *kn);
static int      filt_sowrite(struct knote *kn, long hint);
static int      filt_soempty(struct knote *kn, long hint);
static int inline hhook_run_socket(struct socket *so, void *hctx, int32_t h_id);
fo_kqfilter_t   soo_kqfilter;

static struct filterops soread_filtops = {
        .f_isfd = 1,
        .f_detach = filt_sordetach,
        .f_event = filt_soread,
};
static struct filterops sowrite_filtops = {
        .f_isfd = 1,
        .f_detach = filt_sowdetach,
        .f_event = filt_sowrite,
};
static struct filterops soempty_filtops = {
        .f_isfd = 1,
        .f_detach = filt_sowdetach,
        .f_event = filt_soempty,
};

so_gen_t        so_gencnt;      /* generation count for sockets */

MALLOC_DEFINE(M_SONAME, "soname", "socket name");
MALLOC_DEFINE(M_PCB, "pcb", "protocol control block");

#define VNET_SO_ASSERT(so)                                              \
        VNET_ASSERT(curvnet != NULL,                                    \
            ("%s:%d curvnet is NULL, so=%p", __func__, __LINE__, (so)));

VNET_DEFINE(struct hhook_head *, socket_hhh[HHOOK_SOCKET_LAST + 1]);
#define V_socket_hhh            VNET(socket_hhh)

/*
 * Limit on the number of connections in the listen queue waiting
 * for accept(2).
 * NB: The original sysctl somaxconn is still available but hidden
 * to prevent confusion about the actual purpose of this number.
 */
static u_int somaxconn = SOMAXCONN;

static int
sysctl_somaxconn(SYSCTL_HANDLER_ARGS)
{
        int error;
        int val;

        val = somaxconn;
        error = sysctl_handle_int(oidp, &val, 0, req);
        if (error || !req->newptr )
                return (error);

        /*
         * The purpose of the UINT_MAX / 3 limit, is so that the formula
         *   3 * so_qlimit / 2
         * below, will not overflow.
         */

        if (val < 1 || val > UINT_MAX / 3)
                return (EINVAL);

        somaxconn = val;
        return (0);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, soacceptqueue, CTLTYPE_UINT | CTLFLAG_RW,
    0, sizeof(int), sysctl_somaxconn, "I",
    "Maximum listen socket pending connection accept queue size");
SYSCTL_PROC(_kern_ipc, KIPC_SOMAXCONN, somaxconn,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_SKIP,
    0, sizeof(int), sysctl_somaxconn, "I",
    "Maximum listen socket pending connection accept queue size (compat)");

static int numopensockets;
SYSCTL_INT(_kern_ipc, OID_AUTO, numopensockets, CTLFLAG_RD,
    &numopensockets, 0, "Number of open sockets");

/*
 * accept_mtx locks down per-socket fields relating to accept queues.  See
 * socketvar.h for an annotation of the protected fields of struct socket.
 */
struct mtx accept_mtx;
MTX_SYSINIT(accept_mtx, &accept_mtx, "accept", MTX_DEF);

/*
 * so_global_mtx protects so_gencnt, numopensockets, and the per-socket
 * so_gencnt field.
 */
static struct mtx so_global_mtx;
MTX_SYSINIT(so_global_mtx, &so_global_mtx, "so_glabel", MTX_DEF);

/*
 * General IPC sysctl name space, used by sockets and a variety of other IPC
 * types.
 */
SYSCTL_NODE(_kern, KERN_IPC, ipc, CTLFLAG_RW, 0, "IPC");

/*
 * Initialize the socket subsystem and set up the socket
 * memory allocator.
 */
static uma_zone_t socket_zone;
int     maxsockets;

static void
socket_zone_change(void *tag)
{

        maxsockets = uma_zone_set_max(socket_zone, maxsockets);
}

static void
socket_hhook_register(int subtype)
{
        
        if (hhook_head_register(HHOOK_TYPE_SOCKET, subtype,
            &V_socket_hhh[subtype],
            HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
                printf("%s: WARNING: unable to register hook\n", __func__);
}

static void
socket_hhook_deregister(int subtype)
{
        
        if (hhook_head_deregister(V_socket_hhh[subtype]) != 0)
                printf("%s: WARNING: unable to deregister hook\n", __func__);
}

static void
socket_init(void *tag)
{

        socket_zone = uma_zcreate("socket", sizeof(struct socket), NULL, NULL,
            NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
        maxsockets = uma_zone_set_max(socket_zone, maxsockets);
        uma_zone_set_warning(socket_zone, "kern.ipc.maxsockets limit reached");
        EVENTHANDLER_REGISTER(maxsockets_change, socket_zone_change, NULL,
            EVENTHANDLER_PRI_FIRST);
}
SYSINIT(socket, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY, socket_init, NULL);

static void
socket_vnet_init(const void *unused __unused)
{
        int i;

        /* We expect a contiguous range */
        for (i = 0; i <= HHOOK_SOCKET_LAST; i++)
                socket_hhook_register(i);
}
VNET_SYSINIT(socket_vnet_init, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY,
    socket_vnet_init, NULL);

static void
socket_vnet_uninit(const void *unused __unused)
{
        int i;

        for (i = 0; i <= HHOOK_SOCKET_LAST; i++)
                socket_hhook_deregister(i);
}
VNET_SYSUNINIT(socket_vnet_uninit, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY,
    socket_vnet_uninit, NULL);

/*
 * Initialise maxsockets.  This SYSINIT must be run after
 * tunable_mbinit().
 */
static void
init_maxsockets(void *ignored)
{

        TUNABLE_INT_FETCH("kern.ipc.maxsockets", &maxsockets);
        maxsockets = imax(maxsockets, maxfiles);
}
SYSINIT(param, SI_SUB_TUNABLES, SI_ORDER_ANY, init_maxsockets, NULL);

/*
 * Sysctl to get and set the maximum global sockets limit.  Notify protocols
 * of the change so that they can update their dependent limits as required.
 */
static int
sysctl_maxsockets(SYSCTL_HANDLER_ARGS)
{
        int error, newmaxsockets;

        newmaxsockets = maxsockets;
        error = sysctl_handle_int(oidp, &newmaxsockets, 0, req);
        if (error == 0 && req->newptr) {
                if (newmaxsockets > maxsockets &&
                    newmaxsockets <= maxfiles) {
                        maxsockets = newmaxsockets;
                        EVENTHANDLER_INVOKE(maxsockets_change);
                } else
                        error = EINVAL;
        }
        return (error);
}
SYSCTL_PROC(_kern_ipc, OID_AUTO, maxsockets, CTLTYPE_INT|CTLFLAG_RW,
    &maxsockets, 0, sysctl_maxsockets, "IU",
    "Maximum number of sockets available");

/*
 * Socket operation routines.  These routines are called by the routines in
 * sys_socket.c or from a system process, and implement the semantics of
 * socket operations by switching out to the protocol specific routines.
 */

/*
 * Get a socket structure from our zone, and initialize it.  Note that it
 * would probably be better to allocate socket and PCB at the same time, but
 * I'm not convinced that all the protocols can be easily modified to do
 * this.
 *
 * soalloc() returns a socket with a ref count of 0.
 */
static struct socket *
soalloc(struct vnet *vnet)
{
        struct socket *so;

        so = uma_zalloc(socket_zone, M_NOWAIT | M_ZERO);
        if (so == NULL)
                return (NULL);
#ifdef MAC
        if (mac_socket_init(so, M_NOWAIT) != 0) {
                uma_zfree(socket_zone, so);
                return (NULL);
        }
#endif
        if (khelp_init_osd(HELPER_CLASS_SOCKET, &so->osd)) {
                uma_zfree(socket_zone, so);
                return (NULL);
        }

        /*
         * The socket locking protocol allows to lock 2 sockets at a time,
         * however, the first one must be a listening socket.  WITNESS lacks
         * a feature to change class of an existing lock, so we use DUPOK.
         */
        mtx_init(&so->so_lock, "socket", NULL, MTX_DEF | MTX_DUPOK);
        SOCKBUF_LOCK_INIT(&so->so_snd, "so_snd");
        SOCKBUF_LOCK_INIT(&so->so_rcv, "so_rcv");
        so->so_rcv.sb_sel = &so->so_rdsel;
        so->so_snd.sb_sel = &so->so_wrsel;
        sx_init(&so->so_snd.sb_sx, "so_snd_sx");
        sx_init(&so->so_rcv.sb_sx, "so_rcv_sx");
        TAILQ_INIT(&so->so_snd.sb_aiojobq);
        TAILQ_INIT(&so->so_rcv.sb_aiojobq);
        TASK_INIT(&so->so_snd.sb_aiotask, 0, soaio_snd, so);
        TASK_INIT(&so->so_rcv.sb_aiotask, 0, soaio_rcv, so);
#ifdef VIMAGE
        VNET_ASSERT(vnet != NULL, ("%s:%d vnet is NULL, so=%p",
            __func__, __LINE__, so));
        so->so_vnet = vnet;
#endif
        /* We shouldn't need the so_global_mtx */
        if (hhook_run_socket(so, NULL, HHOOK_SOCKET_CREATE)) {
                /* Do we need more comprehensive error returns? */
                uma_zfree(socket_zone, so);
                return (NULL);
        }
        mtx_lock(&so_global_mtx);
        so->so_gencnt = ++so_gencnt;
        ++numopensockets;
#ifdef VIMAGE
        vnet->vnet_sockcnt++;
#endif
        mtx_unlock(&so_global_mtx);

        return (so);
}

/*
 * Free the storage associated with a socket at the socket layer, tear down
 * locks, labels, etc.  All protocol state is assumed already to have been
 * torn down (and possibly never set up) by the caller.
 */
static void
sodealloc(struct socket *so)
{

        KASSERT(so->so_count == 0, ("sodealloc(): so_count %d", so->so_count));
        KASSERT(so->so_pcb == NULL, ("sodealloc(): so_pcb != NULL"));

        mtx_lock(&so_global_mtx);
        so->so_gencnt = ++so_gencnt;
        --numopensockets;       /* Could be below, but faster here. */
#ifdef VIMAGE
        VNET_ASSERT(so->so_vnet != NULL, ("%s:%d so_vnet is NULL, so=%p",
            __func__, __LINE__, so));
        so->so_vnet->vnet_sockcnt--;
#endif
        mtx_unlock(&so_global_mtx);
#ifdef MAC
        mac_socket_destroy(so);
#endif
        hhook_run_socket(so, NULL, HHOOK_SOCKET_CLOSE);

        crfree(so->so_cred);
        khelp_destroy_osd(&so->osd);
        if (SOLISTENING(so)) {
                if (so->sol_accept_filter != NULL)
                        accept_filt_setopt(so, NULL);
        } else {
                if (so->so_rcv.sb_hiwat)
                        (void)chgsbsize(so->so_cred->cr_uidinfo,
                            &so->so_rcv.sb_hiwat, 0, RLIM_INFINITY);
                if (so->so_snd.sb_hiwat)
                        (void)chgsbsize(so->so_cred->cr_uidinfo,
                            &so->so_snd.sb_hiwat, 0, RLIM_INFINITY);
                sx_destroy(&so->so_snd.sb_sx);
                sx_destroy(&so->so_rcv.sb_sx);
                SOCKBUF_LOCK_DESTROY(&so->so_snd);
                SOCKBUF_LOCK_DESTROY(&so->so_rcv);
        }
        mtx_destroy(&so->so_lock);
        uma_zfree(socket_zone, so);
}

/*
 * socreate returns a socket with a ref count of 1.  The socket should be
 * closed with soclose().
 */
int
socreate(int dom, struct socket **aso, int type, int proto,
    struct ucred *cred, struct thread *td)
{
        struct protosw *prp;
        struct socket *so;
        int error;

        if (proto)
                prp = pffindproto(dom, proto, type);
        else
                prp = pffindtype(dom, type);

        if (prp == NULL) {
                /* No support for domain. */
                if (pffinddomain(dom) == NULL)
                        return (EAFNOSUPPORT);
                /* No support for socket type. */
                if (proto == 0 && type != 0)
                        return (EPROTOTYPE);
                return (EPROTONOSUPPORT);
        }
        if (prp->pr_usrreqs->pru_attach == NULL ||
            prp->pr_usrreqs->pru_attach == pru_attach_notsupp)
                return (EPROTONOSUPPORT);

        if (prison_check_af(cred, prp->pr_domain->dom_family) != 0)
                return (EPROTONOSUPPORT);

        if (prp->pr_type != type)
                return (EPROTOTYPE);
        so = soalloc(CRED_TO_VNET(cred));
        if (so == NULL)
                return (ENOBUFS);

        so->so_type = type;
        so->so_cred = crhold(cred);
        if ((prp->pr_domain->dom_family == PF_INET) ||
            (prp->pr_domain->dom_family == PF_INET6) ||
            (prp->pr_domain->dom_family == PF_ROUTE))
                so->so_fibnum = td->td_proc->p_fibnum;
        else
                so->so_fibnum = 0;
        so->so_proto = prp;
#ifdef MAC
        mac_socket_create(cred, so);
#endif
        knlist_init(&so->so_rdsel.si_note, so, so_rdknl_lock, so_rdknl_unlock,
            so_rdknl_assert_locked, so_rdknl_assert_unlocked);
        knlist_init(&so->so_wrsel.si_note, so, so_wrknl_lock, so_wrknl_unlock,
            so_wrknl_assert_locked, so_wrknl_assert_unlocked);
        /*
         * Auto-sizing of socket buffers is managed by the protocols and
         * the appropriate flags must be set in the pru_attach function.
         */
        CURVNET_SET(so->so_vnet);
        error = (*prp->pr_usrreqs->pru_attach)(so, proto, td);
        CURVNET_RESTORE();
        if (error) {
                sodealloc(so);
                return (error);
        }
        soref(so);
        *aso = so;
        return (0);
}

#ifdef REGRESSION
static int regression_sonewconn_earlytest = 1;
SYSCTL_INT(_regression, OID_AUTO, sonewconn_earlytest, CTLFLAG_RW,
    &regression_sonewconn_earlytest, 0, "Perform early sonewconn limit test");
#endif

/*
 * When an attempt at a new connection is noted on a socket which accepts
 * connections, sonewconn is called.  If the connection is possible (subject
 * to space constraints, etc.) then we allocate a new structure, properly
 * linked into the data structure of the original socket, and return this.
 * Connstatus may be 0, or SS_ISCONFIRMING, or SS_ISCONNECTED.
 *
 * Note: the ref count on the socket is 0 on return.
 */
struct socket *
sonewconn(struct socket *head, int connstatus)
{
        static struct timeval lastover;
        static struct timeval overinterval = { 60, 0 };
        static int overcount;

        struct socket *so;
        u_int over;

        SOLISTEN_LOCK(head);
        over = (head->sol_qlen > 3 * head->sol_qlimit / 2);
        SOLISTEN_UNLOCK(head);
#ifdef REGRESSION
        if (regression_sonewconn_earlytest && over) {
#else
        if (over) {
#endif
                overcount++;

                if (ratecheck(&lastover, &overinterval)) {
                        log(LOG_DEBUG, "%s: pcb %p: Listen queue overflow: "
                            "%i already in queue awaiting acceptance "
                            "(%d occurrences)\n",
                            __func__, head->so_pcb, head->sol_qlen, overcount);

                        overcount = 0;
                }

                return (NULL);
        }
        VNET_ASSERT(head->so_vnet != NULL, ("%s: so %p vnet is NULL",
            __func__, head));
        so = soalloc(head->so_vnet);
        if (so == NULL) {
                log(LOG_DEBUG, "%s: pcb %p: New socket allocation failure: "
                    "limit reached or out of memory\n",
                    __func__, head->so_pcb);
                return (NULL);
        }
        so->so_listen = head;
        so->so_type = head->so_type;
        so->so_linger = head->so_linger;
        so->so_state = head->so_state | SS_NOFDREF;
        so->so_fibnum = head->so_fibnum;
        so->so_proto = head->so_proto;
        so->so_cred = crhold(head->so_cred);
#ifdef MAC
        mac_socket_newconn(head, so);
#endif
        knlist_init(&so->so_rdsel.si_note, so, so_rdknl_lock, so_rdknl_unlock,
            so_rdknl_assert_locked, so_rdknl_assert_unlocked);
        knlist_init(&so->so_wrsel.si_note, so, so_wrknl_lock, so_wrknl_unlock,
            so_wrknl_assert_locked, so_wrknl_assert_unlocked);
        VNET_SO_ASSERT(head);
        if (soreserve(so, head->sol_sbsnd_hiwat, head->sol_sbrcv_hiwat)) {
                sodealloc(so);
                log(LOG_DEBUG, "%s: pcb %p: soreserve() failed\n",
                    __func__, head->so_pcb);
                return (NULL);
        }
        if ((*so->so_proto->pr_usrreqs->pru_attach)(so, 0, NULL)) {
                sodealloc(so);
                log(LOG_DEBUG, "%s: pcb %p: pru_attach() failed\n",
                    __func__, head->so_pcb);
                return (NULL);
        }
        so->so_rcv.sb_lowat = head->sol_sbrcv_lowat;
        so->so_snd.sb_lowat = head->sol_sbsnd_lowat;
        so->so_rcv.sb_timeo = head->sol_sbrcv_timeo;
        so->so_snd.sb_timeo = head->sol_sbsnd_timeo;
        so->so_rcv.sb_flags |= head->sol_sbrcv_flags & SB_AUTOSIZE;
        so->so_snd.sb_flags |= head->sol_sbsnd_flags & SB_AUTOSIZE;

        SOLISTEN_LOCK(head);
        if (head->sol_accept_filter != NULL)
                connstatus = 0;
        so->so_state |= connstatus;
        so->so_options = head->so_options & ~SO_ACCEPTCONN;
        soref(head); /* A socket on (in)complete queue refs head. */
        if (connstatus) {
                TAILQ_INSERT_TAIL(&head->sol_comp, so, so_list);
                so->so_qstate = SQ_COMP;
                head->sol_qlen++;
                solisten_wakeup(head);  /* unlocks */
        } else {
                /*
                 * Keep removing sockets from the head until there's room for
                 * us to insert on the tail.  In pre-locking revisions, this
                 * was a simple if(), but as we could be racing with other
                 * threads and soabort() requires dropping locks, we must
                 * loop waiting for the condition to be true.
                 */
                while (head->sol_incqlen > head->sol_qlimit) {
                        struct socket *sp;

                        sp = TAILQ_FIRST(&head->sol_incomp);
                        TAILQ_REMOVE(&head->sol_incomp, sp, so_list);
                        head->sol_incqlen--;
                        SOCK_LOCK(sp);
                        sp->so_qstate = SQ_NONE;
                        sp->so_listen = NULL;
                        SOCK_UNLOCK(sp);
                        sorele(head);   /* does SOLISTEN_UNLOCK, head stays */
                        soabort(sp);
                        SOLISTEN_LOCK(head);
                }
                TAILQ_INSERT_TAIL(&head->sol_incomp, so, so_list);
                so->so_qstate = SQ_INCOMP;
                head->sol_incqlen++;
                SOLISTEN_UNLOCK(head);
        }
        return (so);
}

#ifdef SCTP
/*
 * Socket part of sctp_peeloff().  Detach a new socket from an
 * association.  The new socket is returned with a reference.
 */
struct socket *
sopeeloff(struct socket *head)
{
        struct socket *so;

        VNET_ASSERT(head->so_vnet != NULL, ("%s:%d so_vnet is NULL, head=%p",
            __func__, __LINE__, head));
        so = soalloc(head->so_vnet);
        if (so == NULL) {
                log(LOG_DEBUG, "%s: pcb %p: New socket allocation failure: "
                    "limit reached or out of memory\n",
                    __func__, head->so_pcb);
                return (NULL);
        }
        so->so_type = head->so_type;
        so->so_options = head->so_options;
        so->so_linger = head->so_linger;
        so->so_state = (head->so_state & SS_NBIO) | SS_ISCONNECTED;
        so->so_fibnum = head->so_fibnum;
        so->so_proto = head->so_proto;
        so->so_cred = crhold(head->so_cred);
#ifdef MAC
        mac_socket_newconn(head, so);
#endif
        knlist_init(&so->so_rdsel.si_note, so, so_rdknl_lock, so_rdknl_unlock,
            so_rdknl_assert_locked, so_rdknl_assert_unlocked);
        knlist_init(&so->so_wrsel.si_note, so, so_wrknl_lock, so_wrknl_unlock,
            so_wrknl_assert_locked, so_wrknl_assert_unlocked);
        VNET_SO_ASSERT(head);
        if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat)) {
                sodealloc(so);
                log(LOG_DEBUG, "%s: pcb %p: soreserve() failed\n",
                    __func__, head->so_pcb);
                return (NULL);
        }
        if ((*so->so_proto->pr_usrreqs->pru_attach)(so, 0, NULL)) {
                sodealloc(so);
                log(LOG_DEBUG, "%s: pcb %p: pru_attach() failed\n",
                    __func__, head->so_pcb);
                return (NULL);
        }
        so->so_rcv.sb_lowat = head->so_rcv.sb_lowat;
        so->so_snd.sb_lowat = head->so_snd.sb_lowat;
        so->so_rcv.sb_timeo = head->so_rcv.sb_timeo;
        so->so_snd.sb_timeo = head->so_snd.sb_timeo;
        so->so_rcv.sb_flags |= head->so_rcv.sb_flags & SB_AUTOSIZE;
        so->so_snd.sb_flags |= head->so_snd.sb_flags & SB_AUTOSIZE;

        soref(so);

        return (so);
}
#endif  /* SCTP */

int
sobind(struct socket *so, struct sockaddr *nam, struct thread *td)
{
        int error;

        CURVNET_SET(so->so_vnet);
        error = (*so->so_proto->pr_usrreqs->pru_bind)(so, nam, td);
        CURVNET_RESTORE();
        return (error);
}

int
sobindat(int fd, struct socket *so, struct sockaddr *nam, struct thread *td)
{
        int error;

        CURVNET_SET(so->so_vnet);
        error = (*so->so_proto->pr_usrreqs->pru_bindat)(fd, so, nam, td);
        CURVNET_RESTORE();
        return (error);
}

/*
 * solisten() transitions a socket from a non-listening state to a listening
 * state, but can also be used to update the listen queue depth on an
 * existing listen socket.  The protocol will call back into the sockets
 * layer using solisten_proto_check() and solisten_proto() to check and set
 * socket-layer listen state.  Call backs are used so that the protocol can
 * acquire both protocol and socket layer locks in whatever order is required
 * by the protocol.
 *
 * Protocol implementors are advised to hold the socket lock across the
 * socket-layer test and set to avoid races at the socket layer.
 */
int
solisten(struct socket *so, int backlog, struct thread *td)
{
        int error;

        CURVNET_SET(so->so_vnet);
        error = (*so->so_proto->pr_usrreqs->pru_listen)(so, backlog, td);
        CURVNET_RESTORE();
        return (error);
}

int
solisten_proto_check(struct socket *so)
{

        SOCK_LOCK_ASSERT(so);

        if (so->so_state & (SS_ISCONNECTED | SS_ISCONNECTING |
            SS_ISDISCONNECTING))
                return (EINVAL);
        return (0);
}

void
solisten_proto(struct socket *so, int backlog)
{
        int sbrcv_lowat, sbsnd_lowat;
        u_int sbrcv_hiwat, sbsnd_hiwat;
        short sbrcv_flags, sbsnd_flags;
        sbintime_t sbrcv_timeo, sbsnd_timeo;

        SOCK_LOCK_ASSERT(so);

        if (SOLISTENING(so))
                goto listening;

        /*
         * Change this socket to listening state.
         */
        sbrcv_lowat = so->so_rcv.sb_lowat;
        sbsnd_lowat = so->so_snd.sb_lowat;
        sbrcv_hiwat = so->so_rcv.sb_hiwat;
        sbsnd_hiwat = so->so_snd.sb_hiwat;
        sbrcv_flags = so->so_rcv.sb_flags;
        sbsnd_flags = so->so_snd.sb_flags;
        sbrcv_timeo = so->so_rcv.sb_timeo;
        sbsnd_timeo = so->so_snd.sb_timeo;

        sbdestroy(&so->so_snd, so);
        sbdestroy(&so->so_rcv, so);
        sx_destroy(&so->so_snd.sb_sx);
        sx_destroy(&so->so_rcv.sb_sx);
        SOCKBUF_LOCK_DESTROY(&so->so_snd);
        SOCKBUF_LOCK_DESTROY(&so->so_rcv);

#ifdef INVARIANTS
        bzero(&so->so_rcv,
            sizeof(struct socket) - offsetof(struct socket, so_rcv));
#endif

        so->sol_sbrcv_lowat = sbrcv_lowat;
        so->sol_sbsnd_lowat = sbsnd_lowat;
        so->sol_sbrcv_hiwat = sbrcv_hiwat;
        so->sol_sbsnd_hiwat = sbsnd_hiwat;
        so->sol_sbrcv_flags = sbrcv_flags;
        so->sol_sbsnd_flags = sbsnd_flags;
        so->sol_sbrcv_timeo = sbrcv_timeo;
        so->sol_sbsnd_timeo = sbsnd_timeo;

        so->sol_qlen = so->sol_incqlen = 0;
        TAILQ_INIT(&so->sol_incomp);
        TAILQ_INIT(&so->sol_comp);

        so->sol_accept_filter = NULL;
        so->sol_accept_filter_arg = NULL;
        so->sol_accept_filter_str = NULL;

        so->sol_upcall = NULL;
        so->sol_upcallarg = NULL;

        so->so_options |= SO_ACCEPTCONN;

listening:
        if (backlog < 0 || backlog > somaxconn)
                backlog = somaxconn;
        so->sol_qlimit = backlog;
}

/*
 * Wakeup listeners/subsystems once we have a complete connection.
 * Enters with lock, returns unlocked.
 */
void
solisten_wakeup(struct socket *sol)
{

        if (sol->sol_upcall != NULL)
                (void )sol->sol_upcall(sol, sol->sol_upcallarg, M_NOWAIT);
        else {
                selwakeuppri(&sol->so_rdsel, PSOCK);
                KNOTE_LOCKED(&sol->so_rdsel.si_note, 0);
        }
        SOLISTEN_UNLOCK(sol);
        wakeup_one(&sol->sol_comp);
}

/*
 * Return single connection off a listening socket queue.  Main consumer of
 * the function is kern_accept4().  Some modules, that do their own accept
 * management also use the function.
 *
 * Listening socket must be locked on entry and is returned unlocked on
 * return.
 * The flags argument is set of accept4(2) flags and ACCEPT4_INHERIT.
 */
int
solisten_dequeue(struct socket *head, struct socket **ret, int flags)
{
        struct socket *so;
        int error;

        SOLISTEN_LOCK_ASSERT(head);

        while (!(head->so_state & SS_NBIO) && TAILQ_EMPTY(&head->sol_comp) &&
            head->so_error == 0) {
                error = msleep(&head->sol_comp, &head->so_lock, PSOCK | PCATCH,
                    "accept", 0);
                if (error != 0) {
                        SOLISTEN_UNLOCK(head);
                        return (error);
                }
        }
        if (head->so_error) {
                error = head->so_error;
                head->so_error = 0;
        } else if ((head->so_state & SS_NBIO) && TAILQ_EMPTY(&head->sol_comp))
                error = EWOULDBLOCK;
        else
                error = 0;
        if (error) {
                SOLISTEN_UNLOCK(head);
                return (error);
        }
        so = TAILQ_FIRST(&head->sol_comp);
        SOCK_LOCK(so);
        KASSERT(so->so_qstate == SQ_COMP,
            ("%s: so %p not SQ_COMP", __func__, so));
        soref(so);
        head->sol_qlen--;
        so->so_qstate = SQ_NONE;
        so->so_listen = NULL;
        TAILQ_REMOVE(&head->sol_comp, so, so_list);
        if (flags & ACCEPT4_INHERIT)
                so->so_state |= (head->so_state & SS_NBIO);
        else
                so->so_state |= (flags & SOCK_NONBLOCK) ? SS_NBIO : 0;
        SOCK_UNLOCK(so);
        sorele(head);

        *ret = so;
        return (0);
}

/*
 * Evaluate the reference count and named references on a socket; if no
 * references remain, free it.  This should be called whenever a reference is
 * released, such as in sorele(), but also when named reference flags are
 * cleared in socket or protocol code.
 *
 * sofree() will free the socket if:
 *
 * - There are no outstanding file descriptor references or related consumers
 *   (so_count == 0).
 *
 * - The socket has been closed by user space, if ever open (SS_NOFDREF).
 *
 * - The protocol does not have an outstanding strong reference on the socket
 *   (SS_PROTOREF).
 *
 * - The socket is not in a completed connection queue, so a process has been
 *   notified that it is present.  If it is removed, the user process may
 *   block in accept() despite select() saying the socket was ready.
 */
void
sofree(struct socket *so)
{
        struct protosw *pr = so->so_proto;

        SOCK_LOCK_ASSERT(so);

        if ((so->so_state & SS_NOFDREF) == 0 || so->so_count != 0 ||
            (so->so_state & SS_PROTOREF) || (so->so_qstate == SQ_COMP)) {
                SOCK_UNLOCK(so);
                return;
        }

        if (!SOLISTENING(so) && so->so_qstate == SQ_INCOMP) {
                struct socket *sol;

                sol = so->so_listen;
                KASSERT(sol, ("%s: so %p on incomp of NULL", __func__, so));

                /*
                 * To solve race between close of a listening socket and
                 * a socket on its incomplete queue, we need to lock both.
                 * The order is first listening socket, then regular.
                 * Since we don't have SS_NOFDREF neither SS_PROTOREF, this
                 * function and the listening socket are the only pointers
                 * to so.  To preserve so and sol, we reference both and then
                 * relock.
                 * After relock the socket may not move to so_comp since it
                 * doesn't have PCB already, but it may be removed from
                 * so_incomp. If that happens, we share responsiblity on
                 * freeing the socket, but soclose() has already removed
                 * it from queue.
                 */
                soref(sol);
                soref(so);
                SOCK_UNLOCK(so);
                SOLISTEN_LOCK(sol);
                SOCK_LOCK(so);
                if (so->so_qstate == SQ_INCOMP) {
                        KASSERT(so->so_listen == sol,
                            ("%s: so %p migrated out of sol %p",
                            __func__, so, sol));
                        TAILQ_REMOVE(&sol->sol_incomp, so, so_list);
                        sol->sol_incqlen--;
                        /* This is guarenteed not to be the last. */
                        refcount_release(&sol->so_count);
                        so->so_qstate = SQ_NONE;
                        so->so_listen = NULL;
                } else
                        KASSERT(so->so_listen == NULL,
                            ("%s: so %p not on (in)comp with so_listen",
                            __func__, so));
                sorele(sol);
                KASSERT(so->so_count == 1,
                    ("%s: so %p count %u", __func__, so, so->so_count));
                so->so_count = 0;
        }
        if (SOLISTENING(so))
                so->so_error = ECONNABORTED;
        SOCK_UNLOCK(so);

        if (so->so_dtor != NULL)
                so->so_dtor(so);

        VNET_SO_ASSERT(so);
        if (pr->pr_flags & PR_RIGHTS && pr->pr_domain->dom_dispose != NULL)
                (*pr->pr_domain->dom_dispose)(so);
        if (pr->pr_usrreqs->pru_detach != NULL)
                (*pr->pr_usrreqs->pru_detach)(so);

        /*
         * From this point on, we assume that no other references to this
         * socket exist anywhere else in the stack.  Therefore, no locks need
         * to be acquired or held.
         *
         * We used to do a lot of socket buffer and socket locking here, as
         * well as invoke sorflush() and perform wakeups.  The direct call to
         * dom_dispose() and sbrelease_internal() are an inlining of what was
         * necessary from sorflush().
         *
         * Notice that the socket buffer and kqueue state are torn down
         * before calling pru_detach.  This means that protocols shold not
         * assume they can perform socket wakeups, etc, in their detach code.
         */
        if (!SOLISTENING(so)) {
                sbdestroy(&so->so_snd, so);
                sbdestroy(&so->so_rcv, so);
        }
        seldrain(&so->so_rdsel);
        seldrain(&so->so_wrsel);
        knlist_destroy(&so->so_rdsel.si_note);
        knlist_destroy(&so->so_wrsel.si_note);
        sodealloc(so);
}

/*
 * Close a socket on last file table reference removal.  Initiate disconnect
 * if connected.  Free socket when disconnect complete.
 *
 * This function will sorele() the socket.  Note that soclose() may be called
 * prior to the ref count reaching zero.  The actual socket structure will
 * not be freed until the ref count reaches zero.
 */
int
soclose(struct socket *so)
{
        struct accept_queue lqueue;
        bool listening;
        int error = 0;

        KASSERT(!(so->so_state & SS_NOFDREF), ("soclose: SS_NOFDREF on enter"));

        CURVNET_SET(so->so_vnet);
        funsetown(&so->so_sigio);
        if (so->so_state & SS_ISCONNECTED) {
                if ((so->so_state & SS_ISDISCONNECTING) == 0) {
                        error = sodisconnect(so);
                        if (error) {
                                if (error == ENOTCONN)
                                        error = 0;
                                goto drop;
                        }
                }
                if (so->so_options & SO_LINGER) {
                        if ((so->so_state & SS_ISDISCONNECTING) &&
                            (so->so_state & SS_NBIO))
                                goto drop;
                        while (so->so_state & SS_ISCONNECTED) {
                                error = tsleep(&so->so_timeo,
                                    PSOCK | PCATCH, "soclos",
                                    so->so_linger * hz);
                                if (error)
                                        break;
                        }
                }
        }

drop:
        if (so->so_proto->pr_usrreqs->pru_close != NULL)
                (*so->so_proto->pr_usrreqs->pru_close)(so);

        SOCK_LOCK(so);
        if ((listening = (so->so_options & SO_ACCEPTCONN))) {
                struct socket *sp;

                TAILQ_INIT(&lqueue);
                TAILQ_SWAP(&lqueue, &so->sol_incomp, socket, so_list);
                TAILQ_CONCAT(&lqueue, &so->sol_comp, so_list);

                so->sol_qlen = so->sol_incqlen = 0;

                TAILQ_FOREACH(sp, &lqueue, so_list) {
                        SOCK_LOCK(sp);
                        sp->so_qstate = SQ_NONE;
                        sp->so_listen = NULL;
                        SOCK_UNLOCK(sp);
                        /* Guaranteed not to be the last. */
                        refcount_release(&so->so_count);
                }
        }
        KASSERT((so->so_state & SS_NOFDREF) == 0, ("soclose: NOFDREF"));
        so->so_state |= SS_NOFDREF;
        sorele(so);
        if (listening) {
                struct socket *sp;

                TAILQ_FOREACH(sp, &lqueue, so_list) {
                        SOCK_LOCK(sp);
                        if (sp->so_count == 0) {
                                SOCK_UNLOCK(sp);
                                soabort(sp);
                        } else
                                /* sp is now in sofree() */
                                SOCK_UNLOCK(sp);
                }
        }
        CURVNET_RESTORE();
        return (error);
}

/*
 * soabort() is used to abruptly tear down a connection, such as when a
 * resource limit is reached (listen queue depth exceeded), or if a listen
 * socket is closed while there are sockets waiting to be accepted.
 *
 * This interface is tricky, because it is called on an unreferenced socket,
 * and must be called only by a thread that has actually removed the socket
 * from the listen queue it was on, or races with other threads are risked.
 *
 * This interface will call into the protocol code, so must not be called
 * with any socket locks held.  Protocols do call it while holding their own
 * recursible protocol mutexes, but this is something that should be subject
 * to review in the future.
 */
void
soabort(struct socket *so)
{

        /*
         * In as much as is possible, assert that no references to this
         * socket are held.  This is not quite the same as asserting that the
         * current thread is responsible for arranging for no references, but
         * is as close as we can get for now.
         */
        KASSERT(so->so_count == 0, ("soabort: so_count"));
        KASSERT((so->so_state & SS_PROTOREF) == 0, ("soabort: SS_PROTOREF"));
        KASSERT(so->so_state & SS_NOFDREF, ("soabort: !SS_NOFDREF"));
        KASSERT(so->so_qstate == SQ_NONE, ("soabort: !SQ_NONE"));
        VNET_SO_ASSERT(so);

        if (so->so_proto->pr_usrreqs->pru_abort != NULL)
                (*so->so_proto->pr_usrreqs->pru_abort)(so);
        SOCK_LOCK(so);
        sofree(so);
}

int
soaccept(struct socket *so, struct sockaddr **nam)
{
        int error;

        SOCK_LOCK(so);
        KASSERT((so->so_state & SS_NOFDREF) != 0, ("soaccept: !NOFDREF"));
        so->so_state &= ~SS_NOFDREF;
        SOCK_UNLOCK(so);

        CURVNET_SET(so->so_vnet);
        error = (*so->so_proto->pr_usrreqs->pru_accept)(so, nam);
        CURVNET_RESTORE();
        return (error);
}

int
soconnect(struct socket *so, struct sockaddr *nam, struct thread *td)
{

        return (soconnectat(AT_FDCWD, so, nam, td));
}

int
soconnectat(int fd, struct socket *so, struct sockaddr *nam, struct thread *td)
{
        int error;

        if (so->so_options & SO_ACCEPTCONN)
                return (EOPNOTSUPP);

        CURVNET_SET(so->so_vnet);
        /*
         * If protocol is connection-based, can only connect once.
         * Otherwise, if connected, try to disconnect first.  This allows
         * user to disconnect by connecting to, e.g., a null address.
         */
        if (so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING) &&
            ((so->so_proto->pr_flags & PR_CONNREQUIRED) ||
            (error = sodisconnect(so)))) {
                error = EISCONN;
        } else {
                /*
                 * Prevent accumulated error from previous connection from
                 * biting us.
                 */
                so->so_error = 0;
                if (fd == AT_FDCWD) {
                        error = (*so->so_proto->pr_usrreqs->pru_connect)(so,
                            nam, td);
                } else {
                        error = (*so->so_proto->pr_usrreqs->pru_connectat)(fd,
                            so, nam, td);
                }
        }
        CURVNET_RESTORE();

        return (error);
}

int
soconnect2(struct socket *so1, struct socket *so2)
{
        int error;

        CURVNET_SET(so1->so_vnet);
        error = (*so1->so_proto->pr_usrreqs->pru_connect2)(so1, so2);
        CURVNET_RESTORE();
        return (error);
}

int
sodisconnect(struct socket *so)
{
        int error;

        if ((so->so_state & SS_ISCONNECTED) == 0)
                return (ENOTCONN);
        if (so->so_state & SS_ISDISCONNECTING)
                return (EALREADY);
        VNET_SO_ASSERT(so);
        error = (*so->so_proto->pr_usrreqs->pru_disconnect)(so);
        return (error);
}

#define SBLOCKWAIT(f)   (((f) & MSG_DONTWAIT) ? 0 : SBL_WAIT)

int
sosend_dgram(struct socket *so, struct sockaddr *addr, struct uio *uio,
    struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
{
        long space;
        ssize_t resid;
        int clen = 0, error, dontroute;

        KASSERT(so->so_type == SOCK_DGRAM, ("sosend_dgram: !SOCK_DGRAM"));
        KASSERT(so->so_proto->pr_flags & PR_ATOMIC,
            ("sosend_dgram: !PR_ATOMIC"));

        if (uio != NULL)
                resid = uio->uio_resid;
        else
                resid = top->m_pkthdr.len;
        /*
         * In theory resid should be unsigned.  However, space must be
         * signed, as it might be less than 0 if we over-committed, and we
         * must use a signed comparison of space and resid.  On the other
         * hand, a negative resid causes us to loop sending 0-length
         * segments to the protocol.
         */
        if (resid < 0) {
                error = EINVAL;
                goto out;
        }

        dontroute =
            (flags & MSG_DONTROUTE) && (so->so_options & SO_DONTROUTE) == 0;
        if (td != NULL)
                td->td_ru.ru_msgsnd++;
        if (control != NULL)
                clen = control->m_len;

        SOCKBUF_LOCK(&so->so_snd);
        if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
                SOCKBUF_UNLOCK(&so->so_snd);
                error = EPIPE;
                goto out;
        }
        if (so->so_error) {
                error = so->so_error;
                so->so_error = 0;
                SOCKBUF_UNLOCK(&so->so_snd);
                goto out;
        }
        if ((so->so_state & SS_ISCONNECTED) == 0) {
                /*
                 * `sendto' and `sendmsg' is allowed on a connection-based
                 * socket if it supports implied connect.  Return ENOTCONN if
                 * not connected and no address is supplied.
                 */
                if ((so->so_proto->pr_flags & PR_CONNREQUIRED) &&
                    (so->so_proto->pr_flags & PR_IMPLOPCL) == 0) {
                        if ((so->so_state & SS_ISCONFIRMING) == 0 &&
                            !(resid == 0 && clen != 0)) {
                                SOCKBUF_UNLOCK(&so->so_snd);
                                error = ENOTCONN;
                                goto out;
                        }
                } else if (addr == NULL) {
                        if (so->so_proto->pr_flags & PR_CONNREQUIRED)
                                error = ENOTCONN;
                        else
                                error = EDESTADDRREQ;
                        SOCKBUF_UNLOCK(&so->so_snd);
                        goto out;
                }
        }

        /*
         * Do we need MSG_OOB support in SOCK_DGRAM?  Signs here may be a
         * problem and need fixing.
         */
        space = sbspace(&so->so_snd);
        if (flags & MSG_OOB)
                space += 1024;
        space -= clen;
        SOCKBUF_UNLOCK(&so->so_snd);
        if (resid > space) {
                error = EMSGSIZE;
                goto out;
        }
        if (uio == NULL) {
                resid = 0;
                if (flags & MSG_EOR)
                        top->m_flags |= M_EOR;
        } else {
                /*
                 * Copy the data from userland into a mbuf chain.
                 * If no data is to be copied in, a single empty mbuf
                 * is returned.
                 */
                top = m_uiotombuf(uio, M_WAITOK, space, max_hdr,
                    (M_PKTHDR | ((flags & MSG_EOR) ? M_EOR : 0)));
                if (top == NULL) {
                        error = EFAULT; /* only possible error */
                        goto out;
                }
                space -= resid - uio->uio_resid;
                resid = uio->uio_resid;
        }
        KASSERT(resid == 0, ("sosend_dgram: resid != 0"));
        /*
         * XXXRW: Frobbing SO_DONTROUTE here is even worse without sblock
         * than with.
         */
        if (dontroute) {
                SOCK_LOCK(so);
                so->so_options |= SO_DONTROUTE;
                SOCK_UNLOCK(so);
        }
        /*
         * XXX all the SBS_CANTSENDMORE checks previously done could be out
         * of date.  We could have received a reset packet in an interrupt or
         * maybe we slept while doing page faults in uiomove() etc.  We could
         * probably recheck again inside the locking protection here, but
         * there are probably other places that this also happens.  We must
         * rethink this.
         */
        VNET_SO_ASSERT(so);
        error = (*so->so_proto->pr_usrreqs->pru_send)(so,
            (flags & MSG_OOB) ? PRUS_OOB :
        /*
         * If the user set MSG_EOF, the protocol understands this flag and
         * nothing left to send then use PRU_SEND_EOF instead of PRU_SEND.
         */
            ((flags & MSG_EOF) &&
             (so->so_proto->pr_flags & PR_IMPLOPCL) &&
             (resid <= 0)) ?
                PRUS_EOF :
                /* If there is more to send set PRUS_MORETOCOME */
                (flags & MSG_MORETOCOME) ||
                (resid > 0 && space > 0) ? PRUS_MORETOCOME : 0,
                top, addr, control, td);
        if (dontroute) {
                SOCK_LOCK(so);
                so->so_options &= ~SO_DONTROUTE;
                SOCK_UNLOCK(so);
        }
        clen = 0;
        control = NULL;
        top = NULL;
out:
        if (top != NULL)
                m_freem(top);
        if (control != NULL)
                m_freem(control);
        return (error);
}

/*
 * Send on a socket.  If send must go all at once and message is larger than
 * send buffering, then hard error.  Lock against other senders.  If must go
 * all at once and not enough room now, then inform user that this would
 * block and do nothing.  Otherwise, if nonblocking, send as much as
 * possible.  The data to be sent is described by "uio" if nonzero, otherwise
 * by the mbuf chain "top" (which must be null if uio is not).  Data provided
 * in mbuf chain must be small enough to send all at once.
 *
 * Returns nonzero on error, timeout or signal; callers must check for short
 * counts if EINTR/ERESTART are returned.  Data and control buffers are freed
 * on return.
 */
int
sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio,
    struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
{
        long space;
        ssize_t resid;
        int clen = 0, error, dontroute;
        int atomic = sosendallatonce(so) || top;

        if (uio != NULL)
                resid = uio->uio_resid;
        else
                resid = top->m_pkthdr.len;
        /*
         * In theory resid should be unsigned.  However, space must be
         * signed, as it might be less than 0 if we over-committed, and we
         * must use a signed comparison of space and resid.  On the other
         * hand, a negative resid causes us to loop sending 0-length
         * segments to the protocol.
         *
         * Also check to make sure that MSG_EOR isn't used on SOCK_STREAM
         * type sockets since that's an error.
         */
        if (resid < 0 || (so->so_type == SOCK_STREAM && (flags & MSG_EOR))) {
                error = EINVAL;
                goto out;
        }

        dontroute =
            (flags & MSG_DONTROUTE) && (so->so_options & SO_DONTROUTE) == 0 &&
            (so->so_proto->pr_flags & PR_ATOMIC);
        if (td != NULL)
                td->td_ru.ru_msgsnd++;
        if (control != NULL)
                clen = control->m_len;

        error = sblock(&so->so_snd, SBLOCKWAIT(flags));
        if (error)
                goto out;

restart:
        do {
                SOCKBUF_LOCK(&so->so_snd);
                if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
                        SOCKBUF_UNLOCK(&so->so_snd);
                        error = EPIPE;
                        goto release;
                }
                if (so->so_error) {
                        error = so->so_error;
                        so->so_error = 0;
                        SOCKBUF_UNLOCK(&so->so_snd);
                        goto release;
                }
                if ((so->so_state & SS_ISCONNECTED) == 0) {
                        /*
                         * `sendto' and `sendmsg' is allowed on a connection-
                         * based socket if it supports implied connect.
                         * Return ENOTCONN if not connected and no address is
                         * supplied.
                         */
                        if ((so->so_proto->pr_flags & PR_CONNREQUIRED) &&
                            (so->so_proto->pr_flags & PR_IMPLOPCL) == 0) {
                                if ((so->so_state & SS_ISCONFIRMING) == 0 &&
                                    !(resid == 0 && clen != 0)) {
                                        SOCKBUF_UNLOCK(&so->so_snd);
                                        error = ENOTCONN;
                                        goto release;
                                }
                        } else if (addr == NULL) {
                                SOCKBUF_UNLOCK(&so->so_snd);
                                if (so->so_proto->pr_flags & PR_CONNREQUIRED)
                                        error = ENOTCONN;
                                else
                                        error = EDESTADDRREQ;
                                goto release;
                        }
                }
                space = sbspace(&so->so_snd);
                if (flags & MSG_OOB)
                        space += 1024;
                if ((atomic && resid > so->so_snd.sb_hiwat) ||
                    clen > so->so_snd.sb_hiwat) {
                        SOCKBUF_UNLOCK(&so->so_snd);
                        error = EMSGSIZE;
                        goto release;
                }
                if (space < resid + clen &&
                    (atomic || space < so->so_snd.sb_lowat || space < clen)) {
                        if ((so->so_state & SS_NBIO) ||
                            (flags & (MSG_NBIO | MSG_DONTWAIT)) != 0) {
                                SOCKBUF_UNLOCK(&so->so_snd);
                                error = EWOULDBLOCK;
                                goto release;
                        }
                        error = sbwait(&so->so_snd);
                        SOCKBUF_UNLOCK(&so->so_snd);
                        if (error)
                                goto release;
                        goto restart;
                }
                SOCKBUF_UNLOCK(&so->so_snd);
                space -= clen;
                do {
                        if (uio == NULL) {
                                resid = 0;
                                if (flags & MSG_EOR)
                                        top->m_flags |= M_EOR;
                        } else {
                                /*
                                 * Copy the data from userland into a mbuf
                                 * chain.  If resid is 0, which can happen
                                 * only if we have control to send, then
                                 * a single empty mbuf is returned.  This
                                 * is a workaround to prevent protocol send
                                 * methods to panic.
                                 */
                                top = m_uiotombuf(uio, M_WAITOK, space,
                                    (atomic ? max_hdr : 0),
                                    (atomic ? M_PKTHDR : 0) |
                                    ((flags & MSG_EOR) ? M_EOR : 0));
                                if (top == NULL) {
                                        error = EFAULT; /* only possible error */
                                        goto release;
                                }
                                space -= resid - uio->uio_resid;
                                resid = uio->uio_resid;
                        }
                        if (dontroute) {
                                SOCK_LOCK(so);
                                so->so_options |= SO_DONTROUTE;
                                SOCK_UNLOCK(so);
                        }
                        /*
                         * XXX all the SBS_CANTSENDMORE checks previously
                         * done could be out of date.  We could have received
                         * a reset packet in an interrupt or maybe we slept
                         * while doing page faults in uiomove() etc.  We
                         * could probably recheck again inside the locking
                         * protection here, but there are probably other
                         * places that this also happens.  We must rethink
                         * this.
                         */
                        VNET_SO_ASSERT(so);
                        error = (*so->so_proto->pr_usrreqs->pru_send)(so,
                            (flags & MSG_OOB) ? PRUS_OOB :
                        /*
                         * If the user set MSG_EOF, the protocol understands
                         * this flag and nothing left to send then use
                         * PRU_SEND_EOF instead of PRU_SEND.
                         */
                            ((flags & MSG_EOF) &&
                             (so->so_proto->pr_flags & PR_IMPLOPCL) &&
                             (resid <= 0)) ?
                                PRUS_EOF :
                        /* If there is more to send set PRUS_MORETOCOME. */
                            (flags & MSG_MORETOCOME) ||
                            (resid > 0 && space > 0) ? PRUS_MORETOCOME : 0,
                            top, addr, control, td);
                        if (dontroute) {
                                SOCK_LOCK(so);
                                so->so_options &= ~SO_DONTROUTE;
                                SOCK_UNLOCK(so);
                        }
                        clen = 0;
                        control = NULL;
                        top = NULL;
                        if (error)
                                goto release;
                } while (resid && space > 0);
        } while (resid);

release:
        sbunlock(&so->so_snd);
out:
        if (top != NULL)
                m_freem(top);
        if (control != NULL)
                m_freem(control);
        return (error);
}

int
sosend(struct socket *so, struct sockaddr *addr, struct uio *uio,
    struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
{
        int error;

        CURVNET_SET(so->so_vnet);
        if (!SOLISTENING(so))
                error = so->so_proto->pr_usrreqs->pru_sosend(so, addr, uio,
                    top, control, flags, td);
        else {
                m_freem(top);
                m_freem(control);
                error = ENOTCONN;
        }
        CURVNET_RESTORE();
        return (error);
}

/*
 * The part of soreceive() that implements reading non-inline out-of-band
 * data from a socket.  For more complete comments, see soreceive(), from
 * which this code originated.
 *
 * Note that soreceive_rcvoob(), unlike the remainder of soreceive(), is
 * unable to return an mbuf chain to the caller.
 */
static int
soreceive_rcvoob(struct socket *so, struct uio *uio, int flags)
{
        struct protosw *pr = so->so_proto;
        struct mbuf *m;
        int error;

        KASSERT(flags & MSG_OOB, ("soreceive_rcvoob: (flags & MSG_OOB) == 0"));
        VNET_SO_ASSERT(so);

        m = m_get(M_WAITOK, MT_DATA);
        error = (*pr->pr_usrreqs->pru_rcvoob)(so, m, flags & MSG_PEEK);
        if (error)
                goto bad;
        do {
                error = uiomove(mtod(m, void *),
                    (int) min(uio->uio_resid, m->m_len), uio);
                m = m_free(m);
        } while (uio->uio_resid && error == 0 && m);
bad:
        if (m != NULL)
                m_freem(m);
        return (error);
}

/*
 * Following replacement or removal of the first mbuf on the first mbuf chain
 * of a socket buffer, push necessary state changes back into the socket
 * buffer so that other consumers see the values consistently.  'nextrecord'
 * is the callers locally stored value of the original value of
 * sb->sb_mb->m_nextpkt which must be restored when the lead mbuf changes.
 * NOTE: 'nextrecord' may be NULL.
 */
static __inline void
sockbuf_pushsync(struct sockbuf *sb, struct mbuf *nextrecord)
{

        SOCKBUF_LOCK_ASSERT(sb);
        /*
         * First, update for the new value of nextrecord.  If necessary, make
         * it the first record.
         */
        if (sb->sb_mb != NULL)
                sb->sb_mb->m_nextpkt = nextrecord;
        else
                sb->sb_mb = nextrecord;

        /*
         * Now update any dependent socket buffer fields to reflect the new
         * state.  This is an expanded inline of SB_EMPTY_FIXUP(), with the
         * addition of a second clause that takes care of the case where
         * sb_mb has been updated, but remains the last record.
         */
        if (sb->sb_mb == NULL) {
                sb->sb_mbtail = NULL;
                sb->sb_lastrecord = NULL;
        } else if (sb->sb_mb->m_nextpkt == NULL)
                sb->sb_lastrecord = sb->sb_mb;
}

/*
 * Implement receive operations on a socket.  We depend on the way that
 * records are added to the sockbuf by sbappend.  In particular, each record
 * (mbufs linked through m_next) must begin with an address if the protocol
 * so specifies, followed by an optional mbuf or mbufs containing ancillary
 * data, and then zero or more mbufs of data.  In order to allow parallelism
 * between network receive and copying to user space, as well as avoid
 * sleeping with a mutex held, we release the socket buffer mutex during the
 * user space copy.  Although the sockbuf is locked, new data may still be
 * appended, and thus we must maintain consistency of the sockbuf during that
 * time.
 *
 * The caller may receive the data as a single mbuf chain by supplying an
 * mbuf **mp0 for use in returning the chain.  The uio is then used only for
 * the count in uio_resid.
 */
int
soreceive_generic(struct socket *so, struct sockaddr **psa, struct uio *uio,
    struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
{
        struct mbuf *m, **mp;
        int flags, error, offset;
        ssize_t len;
        struct protosw *pr = so->so_proto;
        struct mbuf *nextrecord;
        int moff, type = 0;
        ssize_t orig_resid = uio->uio_resid;

        mp = mp0;
        if (psa != NULL)
                *psa = NULL;
        if (controlp != NULL)
                *controlp = NULL;
        if (flagsp != NULL)
                flags = *flagsp &~ MSG_EOR;
        else
                flags = 0;
        if (flags & MSG_OOB)
                return (soreceive_rcvoob(so, uio, flags));
        if (mp != NULL)
                *mp = NULL;
        if ((pr->pr_flags & PR_WANTRCVD) && (so->so_state & SS_ISCONFIRMING)
            && uio->uio_resid) {
                VNET_SO_ASSERT(so);
                (*pr->pr_usrreqs->pru_rcvd)(so, 0);
        }

        error = sblock(&so->so_rcv, SBLOCKWAIT(flags));
        if (error)
                return (error);

restart:
        SOCKBUF_LOCK(&so->so_rcv);
        m = so->so_rcv.sb_mb;
        /*
         * If we have less data than requested, block awaiting more (subject
         * to any timeout) if:
         *   1. the current count is less than the low water mark, or
         *   2. MSG_DONTWAIT is not set
         */
        if (m == NULL || (((flags & MSG_DONTWAIT) == 0 &&
            sbavail(&so->so_rcv) < uio->uio_resid) &&
            sbavail(&so->so_rcv) < so->so_rcv.sb_lowat &&
            m->m_nextpkt == NULL && (pr->pr_flags & PR_ATOMIC) == 0)) {
                KASSERT(m != NULL || !sbavail(&so->so_rcv),
                    ("receive: m == %p sbavail == %u",
                    m, sbavail(&so->so_rcv)));
                if (so->so_error) {
                        if (m != NULL)
                                goto dontblock;
                        error = so->so_error;
                        if ((flags & MSG_PEEK) == 0)
                                so->so_error = 0;
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        goto release;
                }
                SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
                        if (m == NULL) {
                                SOCKBUF_UNLOCK(&so->so_rcv);
                                goto release;
                        } else
                                goto dontblock;
                }
                for (; m != NULL; m = m->m_next)
                        if (m->m_type == MT_OOBDATA  || (m->m_flags & M_EOR)) {
                                m = so->so_rcv.sb_mb;
                                goto dontblock;
                        }
                if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) == 0 &&
                    (so->so_proto->pr_flags & PR_CONNREQUIRED)) {
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        error = ENOTCONN;
                        goto release;
                }
                if (uio->uio_resid == 0) {
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        goto release;
                }
                if ((so->so_state & SS_NBIO) ||
                    (flags & (MSG_DONTWAIT|MSG_NBIO))) {
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        error = EWOULDBLOCK;
                        goto release;
                }
                SBLASTRECORDCHK(&so->so_rcv);
                SBLASTMBUFCHK(&so->so_rcv);
                error = sbwait(&so->so_rcv);
                SOCKBUF_UNLOCK(&so->so_rcv);
                if (error)
                        goto release;
                goto restart;
        }
dontblock:
        /*
         * From this point onward, we maintain 'nextrecord' as a cache of the
         * pointer to the next record in the socket buffer.  We must keep the
         * various socket buffer pointers and local stack versions of the
         * pointers in sync, pushing out modifications before dropping the
         * socket buffer mutex, and re-reading them when picking it up.
         *
         * Otherwise, we will race with the network stack appending new data
         * or records onto the socket buffer by using inconsistent/stale
         * versions of the field, possibly resulting in socket buffer
         * corruption.
         *
         * By holding the high-level sblock(), we prevent simultaneous
         * readers from pulling off the front of the socket buffer.
         */
        SOCKBUF_LOCK_ASSERT(&so->so_rcv);
        if (uio->uio_td)
                uio->uio_td->td_ru.ru_msgrcv++;
        KASSERT(m == so->so_rcv.sb_mb, ("soreceive: m != so->so_rcv.sb_mb"));
        SBLASTRECORDCHK(&so->so_rcv);
        SBLASTMBUFCHK(&so->so_rcv);
        nextrecord = m->m_nextpkt;
        if (pr->pr_flags & PR_ADDR) {
                KASSERT(m->m_type == MT_SONAME,
                    ("m->m_type == %d", m->m_type));
                orig_resid = 0;
                if (psa != NULL)
                        *psa = sodupsockaddr(mtod(m, struct sockaddr *),
                            M_NOWAIT);
                if (flags & MSG_PEEK) {
                        m = m->m_next;
                } else {
                        sbfree(&so->so_rcv, m);
                        so->so_rcv.sb_mb = m_free(m);
                        m = so->so_rcv.sb_mb;
                        sockbuf_pushsync(&so->so_rcv, nextrecord);
                }
        }

        /*
         * Process one or more MT_CONTROL mbufs present before any data mbufs
         * in the first mbuf chain on the socket buffer.  If MSG_PEEK, we
         * just copy the data; if !MSG_PEEK, we call into the protocol to
         * perform externalization (or freeing if controlp == NULL).
         */
        if (m != NULL && m->m_type == MT_CONTROL) {
                struct mbuf *cm = NULL, *cmn;
                struct mbuf **cme = &cm;

                do {
                        if (flags & MSG_PEEK) {
                                if (controlp != NULL) {
                                        *controlp = m_copym(m, 0, m->m_len,
                                            M_NOWAIT);
                                        controlp = &(*controlp)->m_next;
                                }
                                m = m->m_next;
                        } else {
                                sbfree(&so->so_rcv, m);
                                so->so_rcv.sb_mb = m->m_next;
                                m->m_next = NULL;
                                *cme = m;
                                cme = &(*cme)->m_next;
                                m = so->so_rcv.sb_mb;
                        }
                } while (m != NULL && m->m_type == MT_CONTROL);
                if ((flags & MSG_PEEK) == 0)
                        sockbuf_pushsync(&so->so_rcv, nextrecord);
                while (cm != NULL) {
                        cmn = cm->m_next;
                        cm->m_next = NULL;
                        if (pr->pr_domain->dom_externalize != NULL) {
                                SOCKBUF_UNLOCK(&so->so_rcv);
                                VNET_SO_ASSERT(so);
                                error = (*pr->pr_domain->dom_externalize)
                                    (cm, controlp, flags);
                                SOCKBUF_LOCK(&so->so_rcv);
                        } else if (controlp != NULL)
                                *controlp = cm;
                        else
                                m_freem(cm);
                        if (controlp != NULL) {
                                orig_resid = 0;
                                while (*controlp != NULL)
                                        controlp = &(*controlp)->m_next;
                        }
                        cm = cmn;
                }
                if (m != NULL)
                        nextrecord = so->so_rcv.sb_mb->m_nextpkt;
                else
                        nextrecord = so->so_rcv.sb_mb;
                orig_resid = 0;
        }
        if (m != NULL) {
                if ((flags & MSG_PEEK) == 0) {
                        KASSERT(m->m_nextpkt == nextrecord,
                            ("soreceive: post-control, nextrecord !sync"));
                        if (nextrecord == NULL) {
                                KASSERT(so->so_rcv.sb_mb == m,
                                    ("soreceive: post-control, sb_mb!=m"));
                                KASSERT(so->so_rcv.sb_lastrecord == m,
                                    ("soreceive: post-control, lastrecord!=m"));
                        }
                }
                type = m->m_type;
                if (type == MT_OOBDATA)
                        flags |= MSG_OOB;
        } else {
                if ((flags & MSG_PEEK) == 0) {
                        KASSERT(so->so_rcv.sb_mb == nextrecord,
                            ("soreceive: sb_mb != nextrecord"));
                        if (so->so_rcv.sb_mb == NULL) {
                                KASSERT(so->so_rcv.sb_lastrecord == NULL,
                                    ("soreceive: sb_lastercord != NULL"));
                        }
                }
        }
        SOCKBUF_LOCK_ASSERT(&so->so_rcv);
        SBLASTRECORDCHK(&so->so_rcv);
        SBLASTMBUFCHK(&so->so_rcv);

        /*
         * Now continue to read any data mbufs off of the head of the socket
         * buffer until the read request is satisfied.  Note that 'type' is
         * used to store the type of any mbuf reads that have happened so far
         * such that soreceive() can stop reading if the type changes, which
         * causes soreceive() to return only one of regular data and inline
         * out-of-band data in a single socket receive operation.
         */
        moff = 0;
        offset = 0;
        while (m != NULL && !(m->m_flags & M_NOTAVAIL) && uio->uio_resid > 0
            && error == 0) {
                /*
                 * If the type of mbuf has changed since the last mbuf
                 * examined ('type'), end the receive operation.
                 */
                SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                if (m->m_type == MT_OOBDATA || m->m_type == MT_CONTROL) {
                        if (type != m->m_type)
                                break;
                } else if (type == MT_OOBDATA)
                        break;
                else
                    KASSERT(m->m_type == MT_DATA,
                        ("m->m_type == %d", m->m_type));
                so->so_rcv.sb_state &= ~SBS_RCVATMARK;
                len = uio->uio_resid;
                if (so->so_oobmark && len > so->so_oobmark - offset)
                        len = so->so_oobmark - offset;
                if (len > m->m_len - moff)
                        len = m->m_len - moff;
                /*
                 * If mp is set, just pass back the mbufs.  Otherwise copy
                 * them out via the uio, then free.  Sockbuf must be
                 * consistent here (points to current mbuf, it points to next
                 * record) when we drop priority; we must note any additions
                 * to the sockbuf when we block interrupts again.
                 */
                if (mp == NULL) {
                        SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                        SBLASTRECORDCHK(&so->so_rcv);
                        SBLASTMBUFCHK(&so->so_rcv);
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        error = uiomove(mtod(m, char *) + moff, (int)len, uio);
                        SOCKBUF_LOCK(&so->so_rcv);
                        if (error) {
                                /*
                                 * The MT_SONAME mbuf has already been removed
                                 * from the record, so it is necessary to
                                 * remove the data mbufs, if any, to preserve
                                 * the invariant in the case of PR_ADDR that
                                 * requires MT_SONAME mbufs at the head of
                                 * each record.
                                 */
                                if (pr->pr_flags & PR_ATOMIC &&
                                    ((flags & MSG_PEEK) == 0))
                                        (void)sbdroprecord_locked(&so->so_rcv);
                                SOCKBUF_UNLOCK(&so->so_rcv);
                                goto release;
                        }
                } else
                        uio->uio_resid -= len;
                SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                if (len == m->m_len - moff) {
                        if (m->m_flags & M_EOR)
                                flags |= MSG_EOR;
                        if (flags & MSG_PEEK) {
                                m = m->m_next;
                                moff = 0;
                        } else {
                                nextrecord = m->m_nextpkt;
                                sbfree(&so->so_rcv, m);
                                if (mp != NULL) {
                                        m->m_nextpkt = NULL;
                                        *mp = m;
                                        mp = &m->m_next;
                                        so->so_rcv.sb_mb = m = m->m_next;
                                        *mp = NULL;
                                } else {
                                        so->so_rcv.sb_mb = m_free(m);
                                        m = so->so_rcv.sb_mb;
                                }
                                sockbuf_pushsync(&so->so_rcv, nextrecord);
                                SBLASTRECORDCHK(&so->so_rcv);
                                SBLASTMBUFCHK(&so->so_rcv);
                        }
                } else {
                        if (flags & MSG_PEEK)
                                moff += len;
                        else {
                                if (mp != NULL) {
                                        if (flags & MSG_DONTWAIT) {
                                                *mp = m_copym(m, 0, len,
                                                    M_NOWAIT);
                                                if (*mp == NULL) {
                                                        /*
                                                         * m_copym() couldn't
                                                         * allocate an mbuf.
                                                         * Adjust uio_resid back
                                                         * (it was adjusted
                                                         * down by len bytes,
                                                         * which we didn't end
                                                         * up "copying" over).
                                                         */
                                                        uio->uio_resid += len;
                                                        break;
                                                }
                                        } else {
                                                SOCKBUF_UNLOCK(&so->so_rcv);
                                                *mp = m_copym(m, 0, len,
                                                    M_WAITOK);
                                                SOCKBUF_LOCK(&so->so_rcv);
                                        }
                                }
                                sbcut_locked(&so->so_rcv, len);
                        }
                }
                SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                if (so->so_oobmark) {
                        if ((flags & MSG_PEEK) == 0) {
                                so->so_oobmark -= len;
                                if (so->so_oobmark == 0) {
                                        so->so_rcv.sb_state |= SBS_RCVATMARK;
                                        break;
                                }
                        } else {
                                offset += len;
                                if (offset == so->so_oobmark)
                                        break;
                        }
                }
                if (flags & MSG_EOR)
                        break;
                /*
                 * If the MSG_WAITALL flag is set (for non-atomic socket), we
                 * must not quit until "uio->uio_resid == 0" or an error
                 * termination.  If a signal/timeout occurs, return with a
                 * short count but without error.  Keep sockbuf locked
                 * against other readers.
                 */
                while (flags & MSG_WAITALL && m == NULL && uio->uio_resid > 0 &&
                    !sosendallatonce(so) && nextrecord == NULL) {
                        SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                        if (so->so_error ||
                            so->so_rcv.sb_state & SBS_CANTRCVMORE)
                                break;
                        /*
                         * Notify the protocol that some data has been
                         * drained before blocking.
                         */
                        if (pr->pr_flags & PR_WANTRCVD) {
                                SOCKBUF_UNLOCK(&so->so_rcv);
                                VNET_SO_ASSERT(so);
                                (*pr->pr_usrreqs->pru_rcvd)(so, flags);
                                SOCKBUF_LOCK(&so->so_rcv);
                        }
                        SBLASTRECORDCHK(&so->so_rcv);
                        SBLASTMBUFCHK(&so->so_rcv);
                        /*
                         * We could receive some data while was notifying
                         * the protocol. Skip blocking in this case.
                         */
                        if (so->so_rcv.sb_mb == NULL) {
                                error = sbwait(&so->so_rcv);
                                if (error) {
                                        SOCKBUF_UNLOCK(&so->so_rcv);
                                        goto release;
                                }
                        }
                        m = so->so_rcv.sb_mb;
                        if (m != NULL)
                                nextrecord = m->m_nextpkt;
                }
        }

        SOCKBUF_LOCK_ASSERT(&so->so_rcv);
        if (m != NULL && pr->pr_flags & PR_ATOMIC) {
                flags |= MSG_TRUNC;
                if ((flags & MSG_PEEK) == 0)
                        (void) sbdroprecord_locked(&so->so_rcv);
        }
        if ((flags & MSG_PEEK) == 0) {
                if (m == NULL) {
                        /*
                         * First part is an inline SB_EMPTY_FIXUP().  Second
                         * part makes sure sb_lastrecord is up-to-date if
                         * there is still data in the socket buffer.
                         */
                        so->so_rcv.sb_mb = nextrecord;
                        if (so->so_rcv.sb_mb == NULL) {
                                so->so_rcv.sb_mbtail = NULL;
                                so->so_rcv.sb_lastrecord = NULL;
                        } else if (nextrecord->m_nextpkt == NULL)
                                so->so_rcv.sb_lastrecord = nextrecord;
                }
                SBLASTRECORDCHK(&so->so_rcv);
                SBLASTMBUFCHK(&so->so_rcv);
                /*
                 * If soreceive() is being done from the socket callback,
                 * then don't need to generate ACK to peer to update window,
                 * since ACK will be generated on return to TCP.
                 */
                if (!(flags & MSG_SOCALLBCK) &&
                    (pr->pr_flags & PR_WANTRCVD)) {
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        VNET_SO_ASSERT(so);
                        (*pr->pr_usrreqs->pru_rcvd)(so, flags);
                        SOCKBUF_LOCK(&so->so_rcv);
                }
        }
        SOCKBUF_LOCK_ASSERT(&so->so_rcv);
        if (orig_resid == uio->uio_resid && orig_resid &&
            (flags & MSG_EOR) == 0 && (so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0) {
                SOCKBUF_UNLOCK(&so->so_rcv);
                goto restart;
        }
        SOCKBUF_UNLOCK(&so->so_rcv);

        if (flagsp != NULL)
                *flagsp |= flags;
release:
        sbunlock(&so->so_rcv);
        return (error);
}

/*
 * Optimized version of soreceive() for stream (TCP) sockets.
 */
int
soreceive_stream(struct socket *so, struct sockaddr **psa, struct uio *uio,
    struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
{
        int len = 0, error = 0, flags, oresid;
        struct sockbuf *sb;
        struct mbuf *m, *n = NULL;

        /* We only do stream sockets. */
        if (so->so_type != SOCK_STREAM)
                return (EINVAL);
        if (psa != NULL)
                *psa = NULL;
        if (flagsp != NULL)
                flags = *flagsp &~ MSG_EOR;
        else
                flags = 0;
        if (controlp != NULL)
                *controlp = NULL;
        if (flags & MSG_OOB)
                return (soreceive_rcvoob(so, uio, flags));
        if (mp0 != NULL)
                *mp0 = NULL;

        sb = &so->so_rcv;

        /* Prevent other readers from entering the socket. */
        error = sblock(sb, SBLOCKWAIT(flags));
        if (error)
                goto out;
        SOCKBUF_LOCK(sb);

        /* Easy one, no space to copyout anything. */
        if (uio->uio_resid == 0) {
                error = EINVAL;
                goto out;
        }
        oresid = uio->uio_resid;

        /* We will never ever get anything unless we are or were connected. */
        if (!(so->so_state & (SS_ISCONNECTED|SS_ISDISCONNECTED))) {
                error = ENOTCONN;
                goto out;
        }

restart:
        SOCKBUF_LOCK_ASSERT(&so->so_rcv);

        /* Abort if socket has reported problems. */
        if (so->so_error) {
                if (sbavail(sb) > 0)
                        goto deliver;
                if (oresid > uio->uio_resid)
                        goto out;
                error = so->so_error;
                if (!(flags & MSG_PEEK))
                        so->so_error = 0;
                goto out;
        }

        /* Door is closed.  Deliver what is left, if any. */
        if (sb->sb_state & SBS_CANTRCVMORE) {
                if (sbavail(sb) > 0)
                        goto deliver;
                else
                        goto out;
        }

        /* Socket buffer is empty and we shall not block. */
        if (sbavail(sb) == 0 &&
            ((so->so_state & SS_NBIO) || (flags & (MSG_DONTWAIT|MSG_NBIO)))) {
                error = EAGAIN;
                goto out;
        }

        /* Socket buffer got some data that we shall deliver now. */
        if (sbavail(sb) > 0 && !(flags & MSG_WAITALL) &&
            ((so->so_state & SS_NBIO) ||
             (flags & (MSG_DONTWAIT|MSG_NBIO)) ||
             sbavail(sb) >= sb->sb_lowat ||
             sbavail(sb) >= uio->uio_resid ||
             sbavail(sb) >= sb->sb_hiwat) ) {
                goto deliver;
        }

        /* On MSG_WAITALL we must wait until all data or error arrives. */
        if ((flags & MSG_WAITALL) &&
            (sbavail(sb) >= uio->uio_resid || sbavail(sb) >= sb->sb_hiwat))
                goto deliver;

        /*
         * Wait and block until (more) data comes in.
         * NB: Drops the sockbuf lock during wait.
         */
        error = sbwait(sb);
        if (error)
                goto out;
        goto restart;

deliver:
        SOCKBUF_LOCK_ASSERT(&so->so_rcv);
        KASSERT(sbavail(sb) > 0, ("%s: sockbuf empty", __func__));
        KASSERT(sb->sb_mb != NULL, ("%s: sb_mb == NULL", __func__));

        /* Statistics. */
        if (uio->uio_td)
                uio->uio_td->td_ru.ru_msgrcv++;

        /* Fill uio until full or current end of socket buffer is reached. */
        len = min(uio->uio_resid, sbavail(sb));
        if (mp0 != NULL) {
                /* Dequeue as many mbufs as possible. */
                if (!(flags & MSG_PEEK) && len >= sb->sb_mb->m_len) {
                        if (*mp0 == NULL)
                                *mp0 = sb->sb_mb;
                        else
                                m_cat(*mp0, sb->sb_mb);
                        for (m = sb->sb_mb;
                             m != NULL && m->m_len <= len;
                             m = m->m_next) {
                                KASSERT(!(m->m_flags & M_NOTAVAIL),
                                    ("%s: m %p not available", __func__, m));
                                len -= m->m_len;
                                uio->uio_resid -= m->m_len;
                                sbfree(sb, m);
                                n = m;
                        }
                        n->m_next = NULL;
                        sb->sb_mb = m;
                        sb->sb_lastrecord = sb->sb_mb;
                        if (sb->sb_mb == NULL)
                                SB_EMPTY_FIXUP(sb);
                }
                /* Copy the remainder. */
                if (len > 0) {
                        KASSERT(sb->sb_mb != NULL,
                            ("%s: len > 0 && sb->sb_mb empty", __func__));

                        m = m_copym(sb->sb_mb, 0, len, M_NOWAIT);
                        if (m == NULL)
                                len = 0;        /* Don't flush data from sockbuf. */
                        else
                                uio->uio_resid -= len;
                        if (*mp0 != NULL)
                                m_cat(*mp0, m);
                        else
                                *mp0 = m;
                        if (*mp0 == NULL) {
                                error = ENOBUFS;
                                goto out;
                        }
                }
        } else {
                /* NB: Must unlock socket buffer as uiomove may sleep. */
                SOCKBUF_UNLOCK(sb);
                error = m_mbuftouio(uio, sb->sb_mb, len);
                SOCKBUF_LOCK(sb);
                if (error)
                        goto out;
        }
        SBLASTRECORDCHK(sb);
        SBLASTMBUFCHK(sb);

        /*
         * Remove the delivered data from the socket buffer unless we
         * were only peeking.
         */
        if (!(flags & MSG_PEEK)) {
                if (len > 0)
                        sbdrop_locked(sb, len);

                /* Notify protocol that we drained some data. */
                if ((so->so_proto->pr_flags & PR_WANTRCVD) &&
                    (((flags & MSG_WAITALL) && uio->uio_resid > 0) ||
                     !(flags & MSG_SOCALLBCK))) {
                        SOCKBUF_UNLOCK(sb);
                        VNET_SO_ASSERT(so);
                        (*so->so_proto->pr_usrreqs->pru_rcvd)(so, flags);
                        SOCKBUF_LOCK(sb);
                }
        }

        /*
         * For MSG_WAITALL we may have to loop again and wait for
         * more data to come in.
         */
        if ((flags & MSG_WAITALL) && uio->uio_resid > 0)
                goto restart;
out:
        SOCKBUF_LOCK_ASSERT(sb);
        SBLASTRECORDCHK(sb);
        SBLASTMBUFCHK(sb);
        SOCKBUF_UNLOCK(sb);
        sbunlock(sb);
        return (error);
}

/*
 * Optimized version of soreceive() for simple datagram cases from userspace.
 * Unlike in the stream case, we're able to drop a datagram if copyout()
 * fails, and because we handle datagrams atomically, we don't need to use a
 * sleep lock to prevent I/O interlacing.
 */
int
soreceive_dgram(struct socket *so, struct sockaddr **psa, struct uio *uio,
    struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
{
        struct mbuf *m, *m2;
        int flags, error;
        ssize_t len;
        struct protosw *pr = so->so_proto;
        struct mbuf *nextrecord;

        if (psa != NULL)
                *psa = NULL;
        if (controlp != NULL)
                *controlp = NULL;
        if (flagsp != NULL)
                flags = *flagsp &~ MSG_EOR;
        else
                flags = 0;

        /*
         * For any complicated cases, fall back to the full
         * soreceive_generic().
         */
        if (mp0 != NULL || (flags & MSG_PEEK) || (flags & MSG_OOB))
                return (soreceive_generic(so, psa, uio, mp0, controlp,
                    flagsp));

        /*
         * Enforce restrictions on use.
         */
        KASSERT((pr->pr_flags & PR_WANTRCVD) == 0,
            ("soreceive_dgram: wantrcvd"));
        KASSERT(pr->pr_flags & PR_ATOMIC, ("soreceive_dgram: !atomic"));
        KASSERT((so->so_rcv.sb_state & SBS_RCVATMARK) == 0,
            ("soreceive_dgram: SBS_RCVATMARK"));
        KASSERT((so->so_proto->pr_flags & PR_CONNREQUIRED) == 0,
            ("soreceive_dgram: P_CONNREQUIRED"));

        /*
         * Loop blocking while waiting for a datagram.
         */
        SOCKBUF_LOCK(&so->so_rcv);
        while ((m = so->so_rcv.sb_mb) == NULL) {
                KASSERT(sbavail(&so->so_rcv) == 0,
                    ("soreceive_dgram: sb_mb NULL but sbavail %u",
                    sbavail(&so->so_rcv)));
                if (so->so_error) {
                        error = so->so_error;
                        so->so_error = 0;
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        return (error);
                }
                if (so->so_rcv.sb_state & SBS_CANTRCVMORE ||
                    uio->uio_resid == 0) {
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        return (0);
                }
                if ((so->so_state & SS_NBIO) ||
                    (flags & (MSG_DONTWAIT|MSG_NBIO))) {
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        return (EWOULDBLOCK);
                }
                SBLASTRECORDCHK(&so->so_rcv);
                SBLASTMBUFCHK(&so->so_rcv);
                error = sbwait(&so->so_rcv);
                if (error) {
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        return (error);
                }
        }
        SOCKBUF_LOCK_ASSERT(&so->so_rcv);

        if (uio->uio_td)
                uio->uio_td->td_ru.ru_msgrcv++;
        SBLASTRECORDCHK(&so->so_rcv);
        SBLASTMBUFCHK(&so->so_rcv);
        nextrecord = m->m_nextpkt;
        if (nextrecord == NULL) {
                KASSERT(so->so_rcv.sb_lastrecord == m,
                    ("soreceive_dgram: lastrecord != m"));
        }

        KASSERT(so->so_rcv.sb_mb->m_nextpkt == nextrecord,
            ("soreceive_dgram: m_nextpkt != nextrecord"));

        /*
         * Pull 'm' and its chain off the front of the packet queue.
         */
        so->so_rcv.sb_mb = NULL;
        sockbuf_pushsync(&so->so_rcv, nextrecord);

        /*
         * Walk 'm's chain and free that many bytes from the socket buffer.
         */
        for (m2 = m; m2 != NULL; m2 = m2->m_next)
                sbfree(&so->so_rcv, m2);

        /*
         * Do a few last checks before we let go of the lock.
         */
        SBLASTRECORDCHK(&so->so_rcv);
        SBLASTMBUFCHK(&so->so_rcv);
        SOCKBUF_UNLOCK(&so->so_rcv);

        if (pr->pr_flags & PR_ADDR) {
                KASSERT(m->m_type == MT_SONAME,
                    ("m->m_type == %d", m->m_type));
                if (psa != NULL)
                        *psa = sodupsockaddr(mtod(m, struct sockaddr *),
                            M_NOWAIT);
                m = m_free(m);
        }
        if (m == NULL) {
                /* XXXRW: Can this happen? */
                return (0);
        }

        /*
         * Packet to copyout() is now in 'm' and it is disconnected from the
         * queue.
         *
         * Process one or more MT_CONTROL mbufs present before any data mbufs
         * in the first mbuf chain on the socket buffer.  We call into the
         * protocol to perform externalization (or freeing if controlp ==
         * NULL). In some cases there can be only MT_CONTROL mbufs without
         * MT_DATA mbufs.
         */
        if (m->m_type == MT_CONTROL) {
                struct mbuf *cm = NULL, *cmn;
                struct mbuf **cme = &cm;

                do {
                        m2 = m->m_next;
                        m->m_next = NULL;
                        *cme = m;
                        cme = &(*cme)->m_next;
                        m = m2;
                } while (m != NULL && m->m_type == MT_CONTROL);
                while (cm != NULL) {
                        cmn = cm->m_next;
                        cm->m_next = NULL;
                        if (pr->pr_domain->dom_externalize != NULL) {
                                error = (*pr->pr_domain->dom_externalize)
                                    (cm, controlp, flags);
                        } else if (controlp != NULL)
                                *controlp = cm;
                        else
                                m_freem(cm);
                        if (controlp != NULL) {
                                while (*controlp != NULL)
                                        controlp = &(*controlp)->m_next;
                        }
                        cm = cmn;
                }
        }
        KASSERT(m == NULL || m->m_type == MT_DATA,
            ("soreceive_dgram: !data"));
        while (m != NULL && uio->uio_resid > 0) {
                len = uio->uio_resid;
                if (len > m->m_len)
                        len = m->m_len;
                error = uiomove(mtod(m, char *), (int)len, uio);
                if (error) {
                        m_freem(m);
                        return (error);
                }
                if (len == m->m_len)
                        m = m_free(m);
                else {
                        m->m_data += len;
                        m->m_len -= len;
                }
        }
        if (m != NULL) {
                flags |= MSG_TRUNC;
                m_freem(m);
        }
        if (flagsp != NULL)
                *flagsp |= flags;
        return (0);
}

int
soreceive(struct socket *so, struct sockaddr **psa, struct uio *uio,
    struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
{
        int error;

        CURVNET_SET(so->so_vnet);
        if (!SOLISTENING(so))
                error = (so->so_proto->pr_usrreqs->pru_soreceive(so, psa, uio,
                    mp0, controlp, flagsp));
        else
                error = ENOTCONN;
        CURVNET_RESTORE();
        return (error);
}

int
soshutdown(struct socket *so, int how)
{
        struct protosw *pr = so->so_proto;
        int error, soerror_enotconn;

        if (!(how == SHUT_RD || how == SHUT_WR || how == SHUT_RDWR))
                return (EINVAL);

        soerror_enotconn = 0;
        if ((so->so_state &
            (SS_ISCONNECTED | SS_ISCONNECTING | SS_ISDISCONNECTING)) == 0) {
                /*
                 * POSIX mandates us to return ENOTCONN when shutdown(2) is
                 * invoked on a datagram sockets, however historically we would
                 * actually tear socket down. This is known to be leveraged by
                 * some applications to unblock process waiting in recvXXX(2)
                 * by other process that it shares that socket with. Try to meet
                 * both backward-compatibility and POSIX requirements by forcing
                 * ENOTCONN but still asking protocol to perform pru_shutdown().
                 */
                if (so->so_type != SOCK_DGRAM && !SOLISTENING(so))
                        return (ENOTCONN);
                soerror_enotconn = 1;
        }

        if (SOLISTENING(so)) {
                if (how != SHUT_WR) {
                        SOLISTEN_LOCK(so);
                        so->so_error = ECONNABORTED;
                        solisten_wakeup(so);    /* unlocks so */
                }
                goto done;
        }

        CURVNET_SET(so->so_vnet);
        if (pr->pr_usrreqs->pru_flush != NULL)
                (*pr->pr_usrreqs->pru_flush)(so, how);
        if (how != SHUT_WR)
                sorflush(so);
        if (how != SHUT_RD) {
                error = (*pr->pr_usrreqs->pru_shutdown)(so);
                wakeup(&so->so_timeo);
                CURVNET_RESTORE();
                return ((error == 0 && soerror_enotconn) ? ENOTCONN : error);
        }
        wakeup(&so->so_timeo);
        CURVNET_RESTORE();

done:
        return (soerror_enotconn ? ENOTCONN : 0);
}

void
sorflush(struct socket *so)
{
        struct sockbuf *sb = &so->so_rcv;
        struct protosw *pr = so->so_proto;
        struct socket aso;

        VNET_SO_ASSERT(so);

        /*
         * In order to avoid calling dom_dispose with the socket buffer mutex
         * held, and in order to generally avoid holding the lock for a long
         * time, we make a copy of the socket buffer and clear the original
         * (except locks, state).  The new socket buffer copy won't have
         * initialized locks so we can only call routines that won't use or
         * assert those locks.
         *
         * Dislodge threads currently blocked in receive and wait to acquire
         * a lock against other simultaneous readers before clearing the
         * socket buffer.  Don't let our acquire be interrupted by a signal
         * despite any existing socket disposition on interruptable waiting.
         */
        socantrcvmore(so);
        (void) sblock(sb, SBL_WAIT | SBL_NOINTR);

        /*
         * Invalidate/clear most of the sockbuf structure, but leave selinfo
         * and mutex data unchanged.
         */
        SOCKBUF_LOCK(sb);
        bzero(&aso, sizeof(aso));
        aso.so_pcb = so->so_pcb;
        bcopy(&sb->sb_startzero, &aso.so_rcv.sb_startzero,
            sizeof(*sb) - offsetof(struct sockbuf, sb_startzero));
        bzero(&sb->sb_startzero,
            sizeof(*sb) - offsetof(struct sockbuf, sb_startzero));
        SOCKBUF_UNLOCK(sb);
        sbunlock(sb);

        /*
         * Dispose of special rights and flush the copied socket.  Don't call
         * any unsafe routines (that rely on locks being initialized) on aso.
         */
        if (pr->pr_flags & PR_RIGHTS && pr->pr_domain->dom_dispose != NULL)
                (*pr->pr_domain->dom_dispose)(&aso);
        sbrelease_internal(&aso.so_rcv, so);
}

/*
 * Wrapper for Socket established helper hook.
 * Parameters: socket, context of the hook point, hook id.
 */
static int inline
hhook_run_socket(struct socket *so, void *hctx, int32_t h_id)
{
        struct socket_hhook_data hhook_data = {
                .so = so,
                .hctx = hctx,
                .m = NULL,
                .status = 0
        };

        CURVNET_SET(so->so_vnet);
        HHOOKS_RUN_IF(V_socket_hhh[h_id], &hhook_data, &so->osd);
        CURVNET_RESTORE();

        /* Ugly but needed, since hhooks return void for now */
        return (hhook_data.status);
}

/*
 * Perhaps this routine, and sooptcopyout(), below, ought to come in an
 * additional variant to handle the case where the option value needs to be
 * some kind of integer, but not a specific size.  In addition to their use
 * here, these functions are also called by the protocol-level pr_ctloutput()
 * routines.
 */
int
sooptcopyin(struct sockopt *sopt, void *buf, size_t len, size_t minlen)
{
        size_t  valsize;

        /*
         * If the user gives us more than we wanted, we ignore it, but if we
         * don't get the minimum length the caller wants, we return EINVAL.
         * On success, sopt->sopt_valsize is set to however much we actually
         * retrieved.
         */
        if ((valsize = sopt->sopt_valsize) < minlen)
                return EINVAL;
        if (valsize > len)
                sopt->sopt_valsize = valsize = len;

        if (sopt->sopt_td != NULL)
                return (copyin(sopt->sopt_val, buf, valsize));

        bcopy(sopt->sopt_val, buf, valsize);
        return (0);
}

/*
 * Kernel version of setsockopt(2).
 *
 * XXX: optlen is size_t, not socklen_t
 */
int
so_setsockopt(struct socket *so, int level, int optname, void *optval,
    size_t optlen)
{
        struct sockopt sopt;

        sopt.sopt_level = level;
        sopt.sopt_name = optname;
        sopt.sopt_dir = SOPT_SET;
        sopt.sopt_val = optval;
        sopt.sopt_valsize = optlen;
        sopt.sopt_td = NULL;
        return (sosetopt(so, &sopt));
}

int
sosetopt(struct socket *so, struct sockopt *sopt)
{
        int     error, optval;
        struct  linger l;
        struct  timeval tv;
        sbintime_t val;
        uint32_t val32;
#ifdef MAC
        struct mac extmac;
#endif

        CURVNET_SET(so->so_vnet);
        error = 0;
        if (sopt->sopt_level != SOL_SOCKET) {
                if (so->so_proto->pr_ctloutput != NULL) {
                        error = (*so->so_proto->pr_ctloutput)(so, sopt);
                        CURVNET_RESTORE();
                        return (error);
                }
                error = ENOPROTOOPT;
        } else {
                switch (sopt->sopt_name) {
                case SO_ACCEPTFILTER:
                        error = accept_filt_setopt(so, sopt);
                        if (error)
                                goto bad;
                        break;

                case SO_LINGER:
                        error = sooptcopyin(sopt, &l, sizeof l, sizeof l);
                        if (error)
                                goto bad;

                        SOCK_LOCK(so);
                        so->so_linger = l.l_linger;
                        if (l.l_onoff)
                                so->so_options |= SO_LINGER;
                        else
                                so->so_options &= ~SO_LINGER;
                        SOCK_UNLOCK(so);
                        break;

                case SO_DEBUG:
                case SO_KEEPALIVE:
                case SO_DONTROUTE:
                case SO_USELOOPBACK:
                case SO_BROADCAST:
                case SO_REUSEADDR:
                case SO_REUSEPORT:
                case SO_REUSEPORT_LB:
                case SO_OOBINLINE:
                case SO_TIMESTAMP:
                case SO_BINTIME:
                case SO_NOSIGPIPE:
                case SO_NO_DDP:
                case SO_NO_OFFLOAD:
                        error = sooptcopyin(sopt, &optval, sizeof optval,
                            sizeof optval);
                        if (error)
                                goto bad;
                        SOCK_LOCK(so);
                        if (optval)
                                so->so_options |= sopt->sopt_name;
                        else
                                so->so_options &= ~sopt->sopt_name;
                        SOCK_UNLOCK(so);
                        break;

                case SO_SETFIB:
                        error = sooptcopyin(sopt, &optval, sizeof optval,
                            sizeof optval);
                        if (error)
                                goto bad;

                        if (optval < 0 || optval >= rt_numfibs) {
                                error = EINVAL;
                                goto bad;
                        }
                        if (((so->so_proto->pr_domain->dom_family == PF_INET) ||
                           (so->so_proto->pr_domain->dom_family == PF_INET6) ||
                           (so->so_proto->pr_domain->dom_family == PF_ROUTE)))
                                so->so_fibnum = optval;
                        else
                                so->so_fibnum = 0;
                        break;

                case SO_USER_COOKIE:
                        error = sooptcopyin(sopt, &val32, sizeof val32,
                            sizeof val32);
                        if (error)
                                goto bad;
                        so->so_user_cookie = val32;
                        break;

                case SO_SNDBUF:
                case SO_RCVBUF:
                case SO_SNDLOWAT:
                case SO_RCVLOWAT:
                        error = sooptcopyin(sopt, &optval, sizeof optval,
                            sizeof optval);
                        if (error)
                                goto bad;

                        /*
                         * Values < 1 make no sense for any of these options,
                         * so disallow them.
                         */
                        if (optval < 1) {
                                error = EINVAL;
                                goto bad;
                        }

                        error = sbsetopt(so, sopt->sopt_name, optval);
                        break;

                case SO_SNDTIMEO:
                case SO_RCVTIMEO:
#ifdef COMPAT_FREEBSD32
                        if (SV_CURPROC_FLAG(SV_ILP32)) {
                                struct timeval32 tv32;

                                error = sooptcopyin(sopt, &tv32, sizeof tv32,
                                    sizeof tv32);
                                CP(tv32, tv, tv_sec);
                                CP(tv32, tv, tv_usec);
                        } else
#endif
                                error = sooptcopyin(sopt, &tv, sizeof tv,
                                    sizeof tv);
                        if (error)
                                goto bad;
                        if (tv.tv_sec < 0 || tv.tv_usec < 0 ||
                            tv.tv_usec >= 1000000) {
                                error = EDOM;
                                goto bad;
                        }
                        if (tv.tv_sec > INT32_MAX)
                                val = SBT_MAX;
                        else
                                val = tvtosbt(tv);
                        switch (sopt->sopt_name) {
                        case SO_SNDTIMEO:
                                so->so_snd.sb_timeo = val;
                                break;
                        case SO_RCVTIMEO:
                                so->so_rcv.sb_timeo = val;
                                break;
                        }
                        break;

                case SO_LABEL:
#ifdef MAC
                        error = sooptcopyin(sopt, &extmac, sizeof extmac,
                            sizeof extmac);
                        if (error)
                                goto bad;
                        error = mac_setsockopt_label(sopt->sopt_td->td_ucred,
                            so, &extmac);
#else
                        error = EOPNOTSUPP;
#endif
                        break;

                case SO_TS_CLOCK:
                        error = sooptcopyin(sopt, &optval, sizeof optval,
                            sizeof optval);
                        if (error)
                                goto bad;
                        if (optval < 0 || optval > SO_TS_CLOCK_MAX) {
                                error = EINVAL;
                                goto bad;
                        }
                        so->so_ts_clock = optval;
                        break;

                case SO_MAX_PACING_RATE:
                        error = sooptcopyin(sopt, &val32, sizeof(val32),
                            sizeof(val32));
                        if (error)
                                goto bad;
                        so->so_max_pacing_rate = val32;
                        break;

                default:
                        if (V_socket_hhh[HHOOK_SOCKET_OPT]->hhh_nhooks > 0)
                                error = hhook_run_socket(so, sopt,
                                    HHOOK_SOCKET_OPT);
                        else
                                error = ENOPROTOOPT;
                        break;
                }
                if (error == 0 && so->so_proto->pr_ctloutput != NULL)
                        (void)(*so->so_proto->pr_ctloutput)(so, sopt);
        }
bad:
        CURVNET_RESTORE();
        return (error);
}

/*
 * Helper routine for getsockopt.
 */
int
sooptcopyout(struct sockopt *sopt, const void *buf, size_t len)
{
        int     error;
        size_t  valsize;

        error = 0;

        /*
         * Documented get behavior is that we always return a value, possibly
         * truncated to fit in the user's buffer.  Traditional behavior is
         * that we always tell the user precisely how much we copied, rather
         * than something useful like the total amount we had available for
         * her.  Note that this interface is not idempotent; the entire
         * answer must be generated ahead of time.
         */
        valsize = min(len, sopt->sopt_valsize);
        sopt->sopt_valsize = valsize;
        if (sopt->sopt_val != NULL) {
                if (sopt->sopt_td != NULL)
                        error = copyout(buf, sopt->sopt_val, valsize);
                else
                        bcopy(buf, sopt->sopt_val, valsize);
        }
        return (error);
}

int
sogetopt(struct socket *so, struct sockopt *sopt)
{
        int     error, optval;
        struct  linger l;
        struct  timeval tv;
#ifdef MAC
        struct mac extmac;
#endif

        CURVNET_SET(so->so_vnet);
        error = 0;
        if (sopt->sopt_level != SOL_SOCKET) {
                if (so->so_proto->pr_ctloutput != NULL)
                        error = (*so->so_proto->pr_ctloutput)(so, sopt);
                else
                        error = ENOPROTOOPT;
                CURVNET_RESTORE();
                return (error);
        } else {
                switch (sopt->sopt_name) {
                case SO_ACCEPTFILTER:
                        error = accept_filt_getopt(so, sopt);
                        break;

                case SO_LINGER:
                        SOCK_LOCK(so);
                        l.l_onoff = so->so_options & SO_LINGER;
                        l.l_linger = so->so_linger;
                        SOCK_UNLOCK(so);
                        error = sooptcopyout(sopt, &l, sizeof l);
                        break;

                case SO_USELOOPBACK:
                case SO_DONTROUTE:
                case SO_DEBUG:
                case SO_KEEPALIVE:
                case SO_REUSEADDR:
                case SO_REUSEPORT:
                case SO_REUSEPORT_LB:
                case SO_BROADCAST:
                case SO_OOBINLINE:
                case SO_ACCEPTCONN:
                case SO_TIMESTAMP:
                case SO_BINTIME:
                case SO_NOSIGPIPE:
                        optval = so->so_options & sopt->sopt_name;
integer:
                        error = sooptcopyout(sopt, &optval, sizeof optval);
                        break;

                case SO_DOMAIN:
                        optval = so->so_proto->pr_domain->dom_family;
                        goto integer;

                case SO_TYPE:
                        optval = so->so_type;
                        goto integer;

                case SO_PROTOCOL:
                        optval = so->so_proto->pr_protocol;
                        goto integer;

                case SO_ERROR:
                        SOCK_LOCK(so);
                        optval = so->so_error;
                        so->so_error = 0;
                        SOCK_UNLOCK(so);
                        goto integer;

                case SO_SNDBUF:
                        optval = SOLISTENING(so) ? so->sol_sbsnd_hiwat :
                            so->so_snd.sb_hiwat;
                        goto integer;

                case SO_RCVBUF:
                        optval = SOLISTENING(so) ? so->sol_sbrcv_hiwat :
                            so->so_rcv.sb_hiwat;
                        goto integer;

                case SO_SNDLOWAT:
                        optval = SOLISTENING(so) ? so->sol_sbsnd_lowat :
                            so->so_snd.sb_lowat;
                        goto integer;

                case SO_RCVLOWAT:
                        optval = SOLISTENING(so) ? so->sol_sbrcv_lowat :
                            so->so_rcv.sb_lowat;
                        goto integer;

                case SO_SNDTIMEO:
                case SO_RCVTIMEO:
                        tv = sbttotv(sopt->sopt_name == SO_SNDTIMEO ?
                            so->so_snd.sb_timeo : so->so_rcv.sb_timeo);
#ifdef COMPAT_FREEBSD32
                        if (SV_CURPROC_FLAG(SV_ILP32)) {
                                struct timeval32 tv32;

                                CP(tv, tv32, tv_sec);
                                CP(tv, tv32, tv_usec);
                                error = sooptcopyout(sopt, &tv32, sizeof tv32);
                        } else
#endif
                                error = sooptcopyout(sopt, &tv, sizeof tv);
                        break;

                case SO_LABEL:
#ifdef MAC
                        error = sooptcopyin(sopt, &extmac, sizeof(extmac),
                            sizeof(extmac));
                        if (error)
                                goto bad;
                        error = mac_getsockopt_label(sopt->sopt_td->td_ucred,
                            so, &extmac);
                        if (error)
                                goto bad;
                        error = sooptcopyout(sopt, &extmac, sizeof extmac);
#else
                        error = EOPNOTSUPP;
#endif
                        break;

                case SO_PEERLABEL:
#ifdef MAC
                        error = sooptcopyin(sopt, &extmac, sizeof(extmac),
                            sizeof(extmac));
                        if (error)
                                goto bad;
                        error = mac_getsockopt_peerlabel(
                            sopt->sopt_td->td_ucred, so, &extmac);
                        if (error)
                                goto bad;
                        error = sooptcopyout(sopt, &extmac, sizeof extmac);
#else
                        error = EOPNOTSUPP;
#endif
                        break;

                case SO_LISTENQLIMIT:
                        optval = SOLISTENING(so) ? so->sol_qlimit : 0;
                        goto integer;

                case SO_LISTENQLEN:
                        optval = SOLISTENING(so) ? so->sol_qlen : 0;
                        goto integer;

                case SO_LISTENINCQLEN:
                        optval = SOLISTENING(so) ? so->sol_incqlen : 0;
                        goto integer;

                case SO_TS_CLOCK:
                        optval = so->so_ts_clock;
                        goto integer;

                case SO_MAX_PACING_RATE:
                        optval = so->so_max_pacing_rate;
                        goto integer;

                default:
                        if (V_socket_hhh[HHOOK_SOCKET_OPT]->hhh_nhooks > 0)
                                error = hhook_run_socket(so, sopt,
                                    HHOOK_SOCKET_OPT);
                        else
                                error = ENOPROTOOPT;
                        break;
                }
        }
#ifdef MAC
bad:
#endif
        CURVNET_RESTORE();
        return (error);
}

int
soopt_getm(struct sockopt *sopt, struct mbuf **mp)
{
        struct mbuf *m, *m_prev;
        int sopt_size = sopt->sopt_valsize;

        MGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_DATA);
        if (m == NULL)
                return ENOBUFS;
        if (sopt_size > MLEN) {
                MCLGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT);
                if ((m->m_flags & M_EXT) == 0) {
                        m_free(m);
                        return ENOBUFS;
                }
                m->m_len = min(MCLBYTES, sopt_size);
        } else {
                m->m_len = min(MLEN, sopt_size);
        }
        sopt_size -= m->m_len;
        *mp = m;
        m_prev = m;

        while (sopt_size) {
                MGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_DATA);
                if (m == NULL) {
                        m_freem(*mp);
                        return ENOBUFS;
                }
                if (sopt_size > MLEN) {
                        MCLGET(m, sopt->sopt_td != NULL ? M_WAITOK :
                            M_NOWAIT);
                        if ((m->m_flags & M_EXT) == 0) {
                                m_freem(m);
                                m_freem(*mp);
                                return ENOBUFS;
                        }
                        m->m_len = min(MCLBYTES, sopt_size);
                } else {
                        m->m_len = min(MLEN, sopt_size);
                }
                sopt_size -= m->m_len;
                m_prev->m_next = m;
                m_prev = m;
        }
        return (0);
}

int
soopt_mcopyin(struct sockopt *sopt, struct mbuf *m)
{
        struct mbuf *m0 = m;

        if (sopt->sopt_val == NULL)
                return (0);
        while (m != NULL && sopt->sopt_valsize >= m->m_len) {
                if (sopt->sopt_td != NULL) {
                        int error;

                        error = copyin(sopt->sopt_val, mtod(m, char *),
                            m->m_len);
                        if (error != 0) {
                                m_freem(m0);
                                return(error);
                        }
                } else
                        bcopy(sopt->sopt_val, mtod(m, char *), m->m_len);
                sopt->sopt_valsize -= m->m_len;
                sopt->sopt_val = (char *)sopt->sopt_val + m->m_len;
                m = m->m_next;
        }
        if (m != NULL) /* should be allocated enoughly at ip6_sooptmcopyin() */
                panic("ip6_sooptmcopyin");
        return (0);
}

int
soopt_mcopyout(struct sockopt *sopt, struct mbuf *m)
{
        struct mbuf *m0 = m;
        size_t valsize = 0;

        if (sopt->sopt_val == NULL)
                return (0);
        while (m != NULL && sopt->sopt_valsize >= m->m_len) {
                if (sopt->sopt_td != NULL) {
                        int error;

                        error = copyout(mtod(m, char *), sopt->sopt_val,
                            m->m_len);
                        if (error != 0) {
                                m_freem(m0);
                                return(error);
                        }
                } else
                        bcopy(mtod(m, char *), sopt->sopt_val, m->m_len);
                sopt->sopt_valsize -= m->m_len;
                sopt->sopt_val = (char *)sopt->sopt_val + m->m_len;
                valsize += m->m_len;
                m = m->m_next;
        }
        if (m != NULL) {
                /* enough soopt buffer should be given from user-land */
                m_freem(m0);
                return(EINVAL);
        }
        sopt->sopt_valsize = valsize;
        return (0);
}

/*
 * sohasoutofband(): protocol notifies socket layer of the arrival of new
 * out-of-band data, which will then notify socket consumers.
 */
void
sohasoutofband(struct socket *so)
{

        if (so->so_sigio != NULL)
                pgsigio(&so->so_sigio, SIGURG, 0);
        selwakeuppri(&so->so_rdsel, PSOCK);
}

int
sopoll(struct socket *so, int events, struct ucred *active_cred,
    struct thread *td)
{

        /*
         * We do not need to set or assert curvnet as long as everyone uses
         * sopoll_generic().
         */
        return (so->so_proto->pr_usrreqs->pru_sopoll(so, events, active_cred,
            td));
}

int
sopoll_generic(struct socket *so, int events, struct ucred *active_cred,
    struct thread *td)
{
        int revents;

        SOCK_LOCK(so);
        if (SOLISTENING(so)) {
                if (!(events & (POLLIN | POLLRDNORM)))
                        revents = 0;
                else if (!TAILQ_EMPTY(&so->sol_comp))
                        revents = events & (POLLIN | POLLRDNORM);
                else if ((events & POLLINIGNEOF) == 0 && so->so_error)
                        revents = (events & (POLLIN | POLLRDNORM)) | POLLHUP;
                else {
                        selrecord(td, &so->so_rdsel);
                        revents = 0;
                }
        } else {
                revents = 0;
                SOCKBUF_LOCK(&so->so_snd);
                SOCKBUF_LOCK(&so->so_rcv);
                if (events & (POLLIN | POLLRDNORM))
                        if (soreadabledata(so))
                                revents |= events & (POLLIN | POLLRDNORM);
                if (events & (POLLOUT | POLLWRNORM))
                        if (sowriteable(so))
                                revents |= events & (POLLOUT | POLLWRNORM);
                if (events & (POLLPRI | POLLRDBAND))
                        if (so->so_oobmark ||
                            (so->so_rcv.sb_state & SBS_RCVATMARK))
                                revents |= events & (POLLPRI | POLLRDBAND);
                if ((events & POLLINIGNEOF) == 0) {
                        if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
                                revents |= events & (POLLIN | POLLRDNORM);
                                if (so->so_snd.sb_state & SBS_CANTSENDMORE)
                                        revents |= POLLHUP;
                        }
                }
                if (revents == 0) {
                        if (events &
                            (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND)) {
                                selrecord(td, &so->so_rdsel);
                                so->so_rcv.sb_flags |= SB_SEL;
                        }
                        if (events & (POLLOUT | POLLWRNORM)) {
                                selrecord(td, &so->so_wrsel);
                                so->so_snd.sb_flags |= SB_SEL;
                        }
                }
                SOCKBUF_UNLOCK(&so->so_rcv);
                SOCKBUF_UNLOCK(&so->so_snd);
        }
        SOCK_UNLOCK(so);
        return (revents);
}

int
soo_kqfilter(struct file *fp, struct knote *kn)
{
        struct socket *so = kn->kn_fp->f_data;
        struct sockbuf *sb;
        struct knlist *knl;

        switch (kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_fop = &soread_filtops;
                knl = &so->so_rdsel.si_note;
                sb = &so->so_rcv;
                break;
        case EVFILT_WRITE:
                kn->kn_fop = &sowrite_filtops;
                knl = &so->so_wrsel.si_note;
                sb = &so->so_snd;
                break;
        case EVFILT_EMPTY:
                kn->kn_fop = &soempty_filtops;
                knl = &so->so_wrsel.si_note;
                sb = &so->so_snd;
                break;
        default:
                return (EINVAL);
        }

        SOCK_LOCK(so);
        if (SOLISTENING(so)) {
                knlist_add(knl, kn, 1);
        } else {
                SOCKBUF_LOCK(sb);
                knlist_add(knl, kn, 1);
                sb->sb_flags |= SB_KNOTE;
                SOCKBUF_UNLOCK(sb);
        }
        SOCK_UNLOCK(so);
        return (0);
}

/*
 * Some routines that return EOPNOTSUPP for entry points that are not
 * supported by a protocol.  Fill in as needed.
 */
int
pru_accept_notsupp(struct socket *so, struct sockaddr **nam)
{

        return EOPNOTSUPP;
}

int
pru_aio_queue_notsupp(struct socket *so, struct kaiocb *job)
{

        return EOPNOTSUPP;
}

int
pru_attach_notsupp(struct socket *so, int proto, struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_bind_notsupp(struct socket *so, struct sockaddr *nam, struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_bindat_notsupp(int fd, struct socket *so, struct sockaddr *nam,
    struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_connect_notsupp(struct socket *so, struct sockaddr *nam, struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_connectat_notsupp(int fd, struct socket *so, struct sockaddr *nam,
    struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_connect2_notsupp(struct socket *so1, struct socket *so2)
{

        return EOPNOTSUPP;
}

int
pru_control_notsupp(struct socket *so, u_long cmd, caddr_t data,
    struct ifnet *ifp, struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_disconnect_notsupp(struct socket *so)
{

        return EOPNOTSUPP;
}

int
pru_listen_notsupp(struct socket *so, int backlog, struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_peeraddr_notsupp(struct socket *so, struct sockaddr **nam)
{

        return EOPNOTSUPP;
}

int
pru_rcvd_notsupp(struct socket *so, int flags)
{

        return EOPNOTSUPP;
}

int
pru_rcvoob_notsupp(struct socket *so, struct mbuf *m, int flags)
{

        return EOPNOTSUPP;
}

int
pru_send_notsupp(struct socket *so, int flags, struct mbuf *m,
    struct sockaddr *addr, struct mbuf *control, struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_ready_notsupp(struct socket *so, struct mbuf *m, int count)
{

        return (EOPNOTSUPP);
}

/*
 * This isn't really a ``null'' operation, but it's the default one and
 * doesn't do anything destructive.
 */
int
pru_sense_null(struct socket *so, struct stat *sb)
{

        sb->st_blksize = so->so_snd.sb_hiwat;
        return 0;
}

int
pru_shutdown_notsupp(struct socket *so)
{

        return EOPNOTSUPP;
}

int
pru_sockaddr_notsupp(struct socket *so, struct sockaddr **nam)
{

        return EOPNOTSUPP;
}

int
pru_sosend_notsupp(struct socket *so, struct sockaddr *addr, struct uio *uio,
    struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
{

        return EOPNOTSUPP;
}

int
pru_soreceive_notsupp(struct socket *so, struct sockaddr **paddr,
    struct uio *uio, struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
{

        return EOPNOTSUPP;
}

int
pru_sopoll_notsupp(struct socket *so, int events, struct ucred *cred,
    struct thread *td)
{

        return EOPNOTSUPP;
}

static void
filt_sordetach(struct knote *kn)
{
        struct socket *so = kn->kn_fp->f_data;

        so_rdknl_lock(so);
        knlist_remove(&so->so_rdsel.si_note, kn, 1);
        if (!SOLISTENING(so) && knlist_empty(&so->so_rdsel.si_note))
                so->so_rcv.sb_flags &= ~SB_KNOTE;
        so_rdknl_unlock(so);
}

/*ARGSUSED*/
static int
filt_soread(struct knote *kn, long hint)
{
        struct socket *so;

        so = kn->kn_fp->f_data;

        if (SOLISTENING(so)) {
                SOCK_LOCK_ASSERT(so);
                kn->kn_data = so->sol_qlen;
                if (so->so_error) {
                        kn->kn_flags |= EV_EOF;
                        kn->kn_fflags = so->so_error;
                        return (1);
                }
                return (!TAILQ_EMPTY(&so->sol_comp));
        }

        SOCKBUF_LOCK_ASSERT(&so->so_rcv);

        kn->kn_data = sbavail(&so->so_rcv) - so->so_rcv.sb_ctl;
        if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
                kn->kn_flags |= EV_EOF;
                kn->kn_fflags = so->so_error;
                return (1);
        } else if (so->so_error)        /* temporary udp error */
                return (1);

        if (kn->kn_sfflags & NOTE_LOWAT) {
                if (kn->kn_data >= kn->kn_sdata)
                        return (1);
        } else if (sbavail(&so->so_rcv) >= so->so_rcv.sb_lowat)
                return (1);

        /* This hook returning non-zero indicates an event, not error */
        return (hhook_run_socket(so, NULL, HHOOK_FILT_SOREAD));
}

static void
filt_sowdetach(struct knote *kn)
{
        struct socket *so = kn->kn_fp->f_data;

        so_wrknl_lock(so);
        knlist_remove(&so->so_wrsel.si_note, kn, 1);
        if (!SOLISTENING(so) && knlist_empty(&so->so_wrsel.si_note))
                so->so_snd.sb_flags &= ~SB_KNOTE;
        so_wrknl_unlock(so);
}

/*ARGSUSED*/
static int
filt_sowrite(struct knote *kn, long hint)
{
        struct socket *so;

        so = kn->kn_fp->f_data;

        if (SOLISTENING(so))
                return (0);

        SOCKBUF_LOCK_ASSERT(&so->so_snd);
        kn->kn_data = sbspace(&so->so_snd);

        hhook_run_socket(so, kn, HHOOK_FILT_SOWRITE);

        if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
                kn->kn_flags |= EV_EOF;
                kn->kn_fflags = so->so_error;
                return (1);
        } else if (so->so_error)        /* temporary udp error */
                return (1);
        else if (((so->so_state & SS_ISCONNECTED) == 0) &&
            (so->so_proto->pr_flags & PR_CONNREQUIRED))
                return (0);
        else if (kn->kn_sfflags & NOTE_LOWAT)
                return (kn->kn_data >= kn->kn_sdata);
        else
                return (kn->kn_data >= so->so_snd.sb_lowat);
}

static int
filt_soempty(struct knote *kn, long hint)
{
        struct socket *so;

        so = kn->kn_fp->f_data;

        if (SOLISTENING(so))
                return (1);

        SOCKBUF_LOCK_ASSERT(&so->so_snd);
        kn->kn_data = sbused(&so->so_snd);

        if (kn->kn_data == 0)
                return (1);
        else
                return (0);
}

int
socheckuid(struct socket *so, uid_t uid)
{

        if (so == NULL)
                return (EPERM);
        if (so->so_cred->cr_uid != uid)
                return (EPERM);
        return (0);
}

/*
 * These functions are used by protocols to notify the socket layer (and its
 * consumers) of state changes in the sockets driven by protocol-side events.
 */

/*
 * Procedures to manipulate state flags of socket and do appropriate wakeups.
 *
 * Normal sequence from the active (originating) side is that
 * soisconnecting() is called during processing of connect() call, resulting
 * in an eventual call to soisconnected() if/when the connection is
 * established.  When the connection is torn down soisdisconnecting() is
 * called during processing of disconnect() call, and soisdisconnected() is
 * called when the connection to the peer is totally severed.  The semantics
 * of these routines are such that connectionless protocols can call
 * soisconnected() and soisdisconnected() only, bypassing the in-progress
 * calls when setting up a ``connection'' takes no time.
 *
 * From the passive side, a socket is created with two queues of sockets:
 * so_incomp for connections in progress and so_comp for connections already
 * made and awaiting user acceptance.  As a protocol is preparing incoming
 * connections, it creates a socket structure queued on so_incomp by calling
 * sonewconn().  When the connection is established, soisconnected() is
 * called, and transfers the socket structure to so_comp, making it available
 * to accept().
 *
 * If a socket is closed with sockets on either so_incomp or so_comp, these
 * sockets are dropped.
 *
 * If higher-level protocols are implemented in the kernel, the wakeups done
 * here will sometimes cause software-interrupt process scheduling.
 */
void
soisconnecting(struct socket *so)
{

        SOCK_LOCK(so);
        so->so_state &= ~(SS_ISCONNECTED|SS_ISDISCONNECTING);
        so->so_state |= SS_ISCONNECTING;
        SOCK_UNLOCK(so);
}

void
soisconnected(struct socket *so)
{

        SOCK_LOCK(so);
        so->so_state &= ~(SS_ISCONNECTING|SS_ISDISCONNECTING|SS_ISCONFIRMING);
        so->so_state |= SS_ISCONNECTED;

        if (so->so_qstate == SQ_INCOMP) {
                struct socket *head = so->so_listen;
                int ret;

                KASSERT(head, ("%s: so %p on incomp of NULL", __func__, so));
                /*
                 * Promoting a socket from incomplete queue to complete, we
                 * need to go through reverse order of locking.  We first do
                 * trylock, and if that doesn't succeed, we go the hard way
                 * leaving a reference and rechecking consistency after proper
                 * locking.
                 */
                if (__predict_false(SOLISTEN_TRYLOCK(head) == 0)) {
                        soref(head);
                        SOCK_UNLOCK(so);
                        SOLISTEN_LOCK(head);
                        SOCK_LOCK(so);
                        if (__predict_false(head != so->so_listen)) {
                                /*
                                 * The socket went off the listen queue,
                                 * should be lost race to close(2) of sol.
                                 * The socket is about to soabort().
                                 */
                                SOCK_UNLOCK(so);
                                sorele(head);
                                return;
                        }
                        /* Not the last one, as so holds a ref. */
                        refcount_release(&head->so_count);
                }
again:
                if ((so->so_options & SO_ACCEPTFILTER) == 0) {
                        TAILQ_REMOVE(&head->sol_incomp, so, so_list);
                        head->sol_incqlen--;
                        TAILQ_INSERT_TAIL(&head->sol_comp, so, so_list);
                        head->sol_qlen++;
                        so->so_qstate = SQ_COMP;
                        SOCK_UNLOCK(so);
                        solisten_wakeup(head);  /* unlocks */
                } else {
                        SOCKBUF_LOCK(&so->so_rcv);
                        soupcall_set(so, SO_RCV,
                            head->sol_accept_filter->accf_callback,
                            head->sol_accept_filter_arg);
                        so->so_options &= ~SO_ACCEPTFILTER;
                        ret = head->sol_accept_filter->accf_callback(so,
                            head->sol_accept_filter_arg, M_NOWAIT);
                        if (ret == SU_ISCONNECTED) {
                                soupcall_clear(so, SO_RCV);
                                SOCKBUF_UNLOCK(&so->so_rcv);
                                goto again;
                        }
                        SOCKBUF_UNLOCK(&so->so_rcv);
                        SOCK_UNLOCK(so);
                        SOLISTEN_UNLOCK(head);
                }
                return;
        }
        SOCK_UNLOCK(so);
        wakeup(&so->so_timeo);
        sorwakeup(so);
        sowwakeup(so);
}

void
soisdisconnecting(struct socket *so)
{

        SOCK_LOCK(so);
        so->so_state &= ~SS_ISCONNECTING;
        so->so_state |= SS_ISDISCONNECTING;

        if (!SOLISTENING(so)) {
                SOCKBUF_LOCK(&so->so_rcv);
                socantrcvmore_locked(so);
                SOCKBUF_LOCK(&so->so_snd);
                socantsendmore_locked(so);
        }
        SOCK_UNLOCK(so);
        wakeup(&so->so_timeo);
}

void
soisdisconnected(struct socket *so)
{

        SOCK_LOCK(so);
        so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
        so->so_state |= SS_ISDISCONNECTED;

        if (!SOLISTENING(so)) {
                SOCK_UNLOCK(so);
                SOCKBUF_LOCK(&so->so_rcv);
                socantrcvmore_locked(so);
                SOCKBUF_LOCK(&so->so_snd);
                sbdrop_locked(&so->so_snd, sbused(&so->so_snd));
                socantsendmore_locked(so);
        } else
                SOCK_UNLOCK(so);
        wakeup(&so->so_timeo);
}

/*
 * Make a copy of a sockaddr in a malloced buffer of type M_SONAME.
 */
struct sockaddr *
sodupsockaddr(const struct sockaddr *sa, int mflags)
{
        struct sockaddr *sa2;

        sa2 = malloc(sa->sa_len, M_SONAME, mflags);
        if (sa2)
                bcopy(sa, sa2, sa->sa_len);
        return sa2;
}

/*
 * Register per-socket destructor.
 */
void
sodtor_set(struct socket *so, so_dtor_t *func)
{

        SOCK_LOCK_ASSERT(so);
        so->so_dtor = func;
}

/*
 * Register per-socket buffer upcalls.
 */
void
soupcall_set(struct socket *so, int which, so_upcall_t func, void *arg)
{
        struct sockbuf *sb;

        KASSERT(!SOLISTENING(so), ("%s: so %p listening", __func__, so));

        switch (which) {
        case SO_RCV:
                sb = &so->so_rcv;
                break;
        case SO_SND:
                sb = &so->so_snd;
                break;
        default:
                panic("soupcall_set: bad which");
        }
        SOCKBUF_LOCK_ASSERT(sb);
        sb->sb_upcall = func;
        sb->sb_upcallarg = arg;
        sb->sb_flags |= SB_UPCALL;
}

void
soupcall_clear(struct socket *so, int which)
{
        struct sockbuf *sb;

        KASSERT(!SOLISTENING(so), ("%s: so %p listening", __func__, so));

        switch (which) {
        case SO_RCV:
                sb = &so->so_rcv;
                break;
        case SO_SND:
                sb = &so->so_snd;
                break;
        default:
                panic("soupcall_clear: bad which");
        }
        SOCKBUF_LOCK_ASSERT(sb);
        KASSERT(sb->sb_upcall != NULL,
            ("%s: so %p no upcall to clear", __func__, so));
        sb->sb_upcall = NULL;
        sb->sb_upcallarg = NULL;
        sb->sb_flags &= ~SB_UPCALL;
}

void
solisten_upcall_set(struct socket *so, so_upcall_t func, void *arg)
{

        SOLISTEN_LOCK_ASSERT(so);
        so->sol_upcall = func;
        so->sol_upcallarg = arg;
}

static void
so_rdknl_lock(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_LOCK(so);
        else
                SOCKBUF_LOCK(&so->so_rcv);
}

static void
so_rdknl_unlock(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_UNLOCK(so);
        else
                SOCKBUF_UNLOCK(&so->so_rcv);
}

static void
so_rdknl_assert_locked(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_LOCK_ASSERT(so);
        else
                SOCKBUF_LOCK_ASSERT(&so->so_rcv);
}

static void
so_rdknl_assert_unlocked(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_UNLOCK_ASSERT(so);
        else
                SOCKBUF_UNLOCK_ASSERT(&so->so_rcv);
}

static void
so_wrknl_lock(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_LOCK(so);
        else
                SOCKBUF_LOCK(&so->so_snd);
}

static void
so_wrknl_unlock(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_UNLOCK(so);
        else
                SOCKBUF_UNLOCK(&so->so_snd);
}

static void
so_wrknl_assert_locked(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_LOCK_ASSERT(so);
        else
                SOCKBUF_LOCK_ASSERT(&so->so_snd);
}

static void
so_wrknl_assert_unlocked(void *arg)
{
        struct socket *so = arg;

        if (SOLISTENING(so))
                SOCK_UNLOCK_ASSERT(so);
        else
                SOCKBUF_UNLOCK_ASSERT(&so->so_snd);
}

/*
 * Create an external-format (``xsocket'') structure using the information in
 * the kernel-format socket structure pointed to by so.  This is done to
 * reduce the spew of irrelevant information over this interface, to isolate
 * user code from changes in the kernel structure, and potentially to provide
 * information-hiding if we decide that some of this information should be
 * hidden from users.
 */
void
sotoxsocket(struct socket *so, struct xsocket *xso)
{

        bzero(xso, sizeof(*xso));
        xso->xso_len = sizeof *xso;
        xso->xso_so = (uintptr_t)so;
        xso->so_type = so->so_type;
        xso->so_options = so->so_options;
        xso->so_linger = so->so_linger;
        xso->so_state = so->so_state;
        xso->so_pcb = (uintptr_t)so->so_pcb;
        xso->xso_protocol = so->so_proto->pr_protocol;
        xso->xso_family = so->so_proto->pr_domain->dom_family;
        xso->so_timeo = so->so_timeo;
        xso->so_error = so->so_error;
        xso->so_uid = so->so_cred->cr_uid;
        xso->so_pgid = so->so_sigio ? so->so_sigio->sio_pgid : 0;
        if (SOLISTENING(so)) {
                xso->so_qlen = so->sol_qlen;
                xso->so_incqlen = so->sol_incqlen;
                xso->so_qlimit = so->sol_qlimit;
                xso->so_oobmark = 0;
        } else {
                xso->so_state |= so->so_qstate;
                xso->so_qlen = xso->so_incqlen = xso->so_qlimit = 0;
                xso->so_oobmark = so->so_oobmark;
                sbtoxsockbuf(&so->so_snd, &xso->so_snd);
                sbtoxsockbuf(&so->so_rcv, &xso->so_rcv);
        }
}

struct sockbuf *
so_sockbuf_rcv(struct socket *so)
{

        return (&so->so_rcv);
}

struct sockbuf *
so_sockbuf_snd(struct socket *so)
{

        return (&so->so_snd);
}

int
so_state_get(const struct socket *so)
{

        return (so->so_state);
}

void
so_state_set(struct socket *so, int val)
{

        so->so_state = val;
}

int
so_options_get(const struct socket *so)
{

        return (so->so_options);
}

void
so_options_set(struct socket *so, int val)
{

        so->so_options = val;
}

int
so_error_get(const struct socket *so)
{

        return (so->so_error);
}

void
so_error_set(struct socket *so, int val)
{

        so->so_error = val;
}

int
so_linger_get(const struct socket *so)
{

        return (so->so_linger);
}

void
so_linger_set(struct socket *so, int val)
{

        so->so_linger = val;
}

struct protosw *
so_protosw_get(const struct socket *so)
{

        return (so->so_proto);
}

void
so_protosw_set(struct socket *so, struct protosw *val)
{

        so->so_proto = val;
}

void
so_sorwakeup(struct socket *so)
{

        sorwakeup(so);
}

void
so_sowwakeup(struct socket *so)
{

        sowwakeup(so);
}

void
so_sorwakeup_locked(struct socket *so)
{

        sorwakeup_locked(so);
}

void
so_sowwakeup_locked(struct socket *so)
{

        sowwakeup_locked(so);
}

void
so_lock(struct socket *so)
{

        SOCK_LOCK(so);
}

void
so_unlock(struct socket *so)
{

        SOCK_UNLOCK(so);
}