Upgrade OpenSSH to 7.3p1.

[FreeBSD/stable/10.git] / crypto / openssh / clientloop.c

/* $OpenBSD: clientloop.c,v 1.286 2016/07/23 02:54:08 djm Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * The main loop for the interactive session (client side).
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 *
 *
 * Copyright (c) 1999 Theo de Raadt.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 *
 * SSH2 support added by Markus Friedl.
 * Copyright (c) 1999, 2000, 2001 Markus Friedl.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#include "includes.h"

#include <sys/param.h>  /* MIN MAX */
#include <sys/types.h>
#include <sys/ioctl.h>
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <sys/socket.h>

#include <ctype.h>
#include <errno.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <pwd.h>
#include <unistd.h>
#include <limits.h>

#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "ssh.h"
#include "ssh1.h"
#include "ssh2.h"
#include "packet.h"
#include "buffer.h"
#include "compat.h"
#include "channels.h"
#include "dispatch.h"
#include "key.h"
#include "cipher.h"
#include "kex.h"
#include "myproposal.h"
#include "log.h"
#include "misc.h"
#include "readconf.h"
#include "clientloop.h"
#include "sshconnect.h"
#include "authfd.h"
#include "atomicio.h"
#include "sshpty.h"
#include "match.h"
#include "msg.h"
#include "ssherr.h"
#include "hostfile.h"

/* import options */
extern Options options;

/* Flag indicating that stdin should be redirected from /dev/null. */
extern int stdin_null_flag;

/* Flag indicating that no shell has been requested */
extern int no_shell_flag;

/* Flag indicating that ssh should daemonise after authentication is complete */
extern int fork_after_authentication_flag;

/* Control socket */
extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */

/*
 * Name of the host we are connecting to.  This is the name given on the
 * command line, or the HostName specified for the user-supplied name in a
 * configuration file.
 */
extern char *host;

/*
 * Flag to indicate that we have received a window change signal which has
 * not yet been processed.  This will cause a message indicating the new
 * window size to be sent to the server a little later.  This is volatile
 * because this is updated in a signal handler.
 */
static volatile sig_atomic_t received_window_change_signal = 0;
static volatile sig_atomic_t received_signal = 0;

/* Flag indicating whether the user's terminal is in non-blocking mode. */
static int in_non_blocking_mode = 0;

/* Time when backgrounded control master using ControlPersist should exit */
static time_t control_persist_exit_time = 0;

/* Common data for the client loop code. */
volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
static int escape_char1;        /* Escape character. (proto1 only) */
static int escape_pending1;     /* Last character was an escape (proto1 only) */
static int last_was_cr;         /* Last character was a newline. */
static int exit_status;         /* Used to store the command exit status. */
static int stdin_eof;           /* EOF has been encountered on stderr. */
static Buffer stdin_buffer;     /* Buffer for stdin data. */
static Buffer stdout_buffer;    /* Buffer for stdout data. */
static Buffer stderr_buffer;    /* Buffer for stderr data. */
static u_int buffer_high;       /* Soft max buffer size. */
static int connection_in;       /* Connection to server (input). */
static int connection_out;      /* Connection to server (output). */
static int need_rekeying;       /* Set to non-zero if rekeying is requested. */
static int session_closed;      /* In SSH2: login session closed. */
static u_int x11_refuse_time;   /* If >0, refuse x11 opens after this time. */

static void client_init_dispatch(void);
int     session_ident = -1;

/* Track escape per proto2 channel */
struct escape_filter_ctx {
        int escape_pending;
        int escape_char;
};

/* Context for channel confirmation replies */
struct channel_reply_ctx {
        const char *request_type;
        int id;
        enum confirm_action action;
};

/* Global request success/failure callbacks */
struct global_confirm {
        TAILQ_ENTRY(global_confirm) entry;
        global_confirm_cb *cb;
        void *ctx;
        int ref_count;
};
TAILQ_HEAD(global_confirms, global_confirm);
static struct global_confirms global_confirms =
    TAILQ_HEAD_INITIALIZER(global_confirms);

void ssh_process_session2_setup(int, int, int, Buffer *);

/* Restores stdin to blocking mode. */

static void
leave_non_blocking(void)
{
        if (in_non_blocking_mode) {
                unset_nonblock(fileno(stdin));
                in_non_blocking_mode = 0;
        }
}

/* Puts stdin terminal in non-blocking mode. */

static void
enter_non_blocking(void)
{
        in_non_blocking_mode = 1;
        set_nonblock(fileno(stdin));
}

/*
 * Signal handler for the window change signal (SIGWINCH).  This just sets a
 * flag indicating that the window has changed.
 */
/*ARGSUSED */
static void
window_change_handler(int sig)
{
        received_window_change_signal = 1;
        signal(SIGWINCH, window_change_handler);
}

/*
 * Signal handler for signals that cause the program to terminate.  These
 * signals must be trapped to restore terminal modes.
 */
/*ARGSUSED */
static void
signal_handler(int sig)
{
        received_signal = sig;
        quit_pending = 1;
}

/*
 * Returns current time in seconds from Jan 1, 1970 with the maximum
 * available resolution.
 */

static double
get_current_time(void)
{
        struct timeval tv;
        gettimeofday(&tv, NULL);
        return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
}

/*
 * Sets control_persist_exit_time to the absolute time when the
 * backgrounded control master should exit due to expiry of the
 * ControlPersist timeout.  Sets it to 0 if we are not a backgrounded
 * control master process, or if there is no ControlPersist timeout.
 */
static void
set_control_persist_exit_time(void)
{
        if (muxserver_sock == -1 || !options.control_persist
            || options.control_persist_timeout == 0) {
                /* not using a ControlPersist timeout */
                control_persist_exit_time = 0;
        } else if (channel_still_open()) {
                /* some client connections are still open */
                if (control_persist_exit_time > 0)
                        debug2("%s: cancel scheduled exit", __func__);
                control_persist_exit_time = 0;
        } else if (control_persist_exit_time <= 0) {
                /* a client connection has recently closed */
                control_persist_exit_time = monotime() +
                        (time_t)options.control_persist_timeout;
                debug2("%s: schedule exit in %d seconds", __func__,
                    options.control_persist_timeout);
        }
        /* else we are already counting down to the timeout */
}

#define SSH_X11_VALID_DISPLAY_CHARS ":/.-_"
static int
client_x11_display_valid(const char *display)
{
        size_t i, dlen;

        if (display == NULL)
                return 0;

        dlen = strlen(display);
        for (i = 0; i < dlen; i++) {
                if (!isalnum((u_char)display[i]) &&
                    strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) {
                        debug("Invalid character '%c' in DISPLAY", display[i]);
                        return 0;
                }
        }
        return 1;
}

#define SSH_X11_PROTO           "MIT-MAGIC-COOKIE-1"
#define X11_TIMEOUT_SLACK       60
int
client_x11_get_proto(const char *display, const char *xauth_path,
    u_int trusted, u_int timeout, char **_proto, char **_data)
{
        char cmd[1024], line[512], xdisplay[512];
        char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
        static char proto[512], data[512];
        FILE *f;
        int got_data = 0, generated = 0, do_unlink = 0, i, r;
        struct stat st;
        u_int now, x11_timeout_real;

        *_proto = proto;
        *_data = data;
        proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0';

        if (!client_x11_display_valid(display)) {
                if (display != NULL)
                        logit("DISPLAY \"%s\" invalid; disabling X11 forwarding",
                            display);
                return -1;
        }
        if (xauth_path != NULL && stat(xauth_path, &st) == -1) {
                debug("No xauth program.");
                xauth_path = NULL;
        }

        if (xauth_path != NULL) {
                /*
                 * Handle FamilyLocal case where $DISPLAY does
                 * not match an authorization entry.  For this we
                 * just try "xauth list unix:displaynum.screennum".
                 * XXX: "localhost" match to determine FamilyLocal
                 *      is not perfect.
                 */
                if (strncmp(display, "localhost:", 10) == 0) {
                        if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
                            display + 10)) < 0 ||
                            (size_t)r >= sizeof(xdisplay)) {
                                error("%s: display name too long", __func__);
                                return -1;
                        }
                        display = xdisplay;
                }
                if (trusted == 0) {
                        /*
                         * Generate an untrusted X11 auth cookie.
                         *
                         * The authentication cookie should briefly outlive
                         * ssh's willingness to forward X11 connections to
                         * avoid nasty fail-open behaviour in the X server.
                         */
                        mktemp_proto(xauthdir, sizeof(xauthdir));
                        if (mkdtemp(xauthdir) == NULL) {
                                error("%s: mkdtemp: %s",
                                    __func__, strerror(errno));
                                return -1;
                        }
                        do_unlink = 1;
                        if ((r = snprintf(xauthfile, sizeof(xauthfile),
                            "%s/xauthfile", xauthdir)) < 0 ||
                            (size_t)r >= sizeof(xauthfile)) {
                                error("%s: xauthfile path too long", __func__);
                                unlink(xauthfile);
                                rmdir(xauthdir);
                                return -1;
                        }

                        if (timeout >= UINT_MAX - X11_TIMEOUT_SLACK)
                                x11_timeout_real = UINT_MAX;
                        else
                                x11_timeout_real = timeout + X11_TIMEOUT_SLACK;
                        if ((r = snprintf(cmd, sizeof(cmd),
                            "%s -f %s generate %s " SSH_X11_PROTO
                            " untrusted timeout %u 2>" _PATH_DEVNULL,
                            xauth_path, xauthfile, display,
                            x11_timeout_real)) < 0 ||
                            (size_t)r >= sizeof(cmd))
                                fatal("%s: cmd too long", __func__);
                        debug2("%s: %s", __func__, cmd);
                        if (x11_refuse_time == 0) {
                                now = monotime() + 1;
                                if (UINT_MAX - timeout < now)
                                        x11_refuse_time = UINT_MAX;
                                else
                                        x11_refuse_time = now + timeout;
                                channel_set_x11_refuse_time(x11_refuse_time);
                        }
                        if (system(cmd) == 0)
                                generated = 1;
                }

                /*
                 * When in untrusted mode, we read the cookie only if it was
                 * successfully generated as an untrusted one in the step
                 * above.
                 */
                if (trusted || generated) {
                        snprintf(cmd, sizeof(cmd),
                            "%s %s%s list %s 2>" _PATH_DEVNULL,
                            xauth_path,
                            generated ? "-f " : "" ,
                            generated ? xauthfile : "",
                            display);
                        debug2("x11_get_proto: %s", cmd);
                        f = popen(cmd, "r");
                        if (f && fgets(line, sizeof(line), f) &&
                            sscanf(line, "%*s %511s %511s", proto, data) == 2)
                                got_data = 1;
                        if (f)
                                pclose(f);
                }
        }

        if (do_unlink) {
                unlink(xauthfile);
                rmdir(xauthdir);
        }

        /* Don't fall back to fake X11 data for untrusted forwarding */
        if (!trusted && !got_data) {
                error("Warning: untrusted X11 forwarding setup failed: "
                    "xauth key data not generated");
                return -1;
        }

        /*
         * If we didn't get authentication data, just make up some
         * data.  The forwarding code will check the validity of the
         * response anyway, and substitute this data.  The X11
         * server, however, will ignore this fake data and use
         * whatever authentication mechanisms it was using otherwise
         * for the local connection.
         */
        if (!got_data) {
                u_int32_t rnd = 0;

                logit("Warning: No xauth data; "
                    "using fake authentication data for X11 forwarding.");
                strlcpy(proto, SSH_X11_PROTO, sizeof proto);
                for (i = 0; i < 16; i++) {
                        if (i % 4 == 0)
                                rnd = arc4random();
                        snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
                            rnd & 0xff);
                        rnd >>= 8;
                }
        }

        return 0;
}

/*
 * This is called when the interactive is entered.  This checks if there is
 * an EOF coming on stdin.  We must check this explicitly, as select() does
 * not appear to wake up when redirecting from /dev/null.
 */

static void
client_check_initial_eof_on_stdin(void)
{
        int len;
        char buf[1];

        /*
         * If standard input is to be "redirected from /dev/null", we simply
         * mark that we have seen an EOF and send an EOF message to the
         * server. Otherwise, we try to read a single character; it appears
         * that for some files, such /dev/null, select() never wakes up for
         * read for this descriptor, which means that we never get EOF.  This
         * way we will get the EOF if stdin comes from /dev/null or similar.
         */
        if (stdin_null_flag) {
                /* Fake EOF on stdin. */
                debug("Sending eof.");
                stdin_eof = 1;
                packet_start(SSH_CMSG_EOF);
                packet_send();
        } else {
                enter_non_blocking();

                /* Check for immediate EOF on stdin. */
                len = read(fileno(stdin), buf, 1);
                if (len == 0) {
                        /*
                         * EOF.  Record that we have seen it and send
                         * EOF to server.
                         */
                        debug("Sending eof.");
                        stdin_eof = 1;
                        packet_start(SSH_CMSG_EOF);
                        packet_send();
                } else if (len > 0) {
                        /*
                         * Got data.  We must store the data in the buffer,
                         * and also process it as an escape character if
                         * appropriate.
                         */
                        if ((u_char) buf[0] == escape_char1)
                                escape_pending1 = 1;
                        else
                                buffer_append(&stdin_buffer, buf, 1);
                }
                leave_non_blocking();
        }
}


/*
 * Make packets from buffered stdin data, and buffer them for sending to the
 * connection.
 */

static void
client_make_packets_from_stdin_data(void)
{
        u_int len;

        /* Send buffered stdin data to the server. */
        while (buffer_len(&stdin_buffer) > 0 &&
            packet_not_very_much_data_to_write()) {
                len = buffer_len(&stdin_buffer);
                /* Keep the packets at reasonable size. */
                if (len > packet_get_maxsize())
                        len = packet_get_maxsize();
                packet_start(SSH_CMSG_STDIN_DATA);
                packet_put_string(buffer_ptr(&stdin_buffer), len);
                packet_send();
                buffer_consume(&stdin_buffer, len);
                /* If we have a pending EOF, send it now. */
                if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
                        packet_start(SSH_CMSG_EOF);
                        packet_send();
                }
        }
}

/*
 * Checks if the client window has changed, and sends a packet about it to
 * the server if so.  The actual change is detected elsewhere (by a software
 * interrupt on Unix); this just checks the flag and sends a message if
 * appropriate.
 */

static void
client_check_window_change(void)
{
        struct winsize ws;

        if (! received_window_change_signal)
                return;
        /** XXX race */
        received_window_change_signal = 0;

        debug2("client_check_window_change: changed");

        if (compat20) {
                channel_send_window_changes();
        } else {
                if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
                        return;
                packet_start(SSH_CMSG_WINDOW_SIZE);
                packet_put_int((u_int)ws.ws_row);
                packet_put_int((u_int)ws.ws_col);
                packet_put_int((u_int)ws.ws_xpixel);
                packet_put_int((u_int)ws.ws_ypixel);
                packet_send();
        }
}

static int
client_global_request_reply(int type, u_int32_t seq, void *ctxt)
{
        struct global_confirm *gc;

        if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
                return 0;
        if (gc->cb != NULL)
                gc->cb(type, seq, gc->ctx);
        if (--gc->ref_count <= 0) {
                TAILQ_REMOVE(&global_confirms, gc, entry);
                explicit_bzero(gc, sizeof(*gc));
                free(gc);
        }

        packet_set_alive_timeouts(0);
        return 0;
}

static void
server_alive_check(void)
{
        if (packet_inc_alive_timeouts() > options.server_alive_count_max) {
                logit("Timeout, server %s not responding.", host);
                cleanup_exit(255);
        }
        packet_start(SSH2_MSG_GLOBAL_REQUEST);
        packet_put_cstring("keepalive@openssh.com");
        packet_put_char(1);     /* boolean: want reply */
        packet_send();
        /* Insert an empty placeholder to maintain ordering */
        client_register_global_confirm(NULL, NULL);
}

/*
 * Waits until the client can do something (some data becomes available on
 * one of the file descriptors).
 */
static void
client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
    int *maxfdp, u_int *nallocp, int rekeying)
{
        struct timeval tv, *tvp;
        int timeout_secs;
        time_t minwait_secs = 0, server_alive_time = 0, now = monotime();
        int ret;

        /* Add any selections by the channel mechanism. */
        channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
            &minwait_secs, rekeying);

        if (!compat20) {
                /* Read from the connection, unless our buffers are full. */
                if (buffer_len(&stdout_buffer) < buffer_high &&
                    buffer_len(&stderr_buffer) < buffer_high &&
                    channel_not_very_much_buffered_data())
                        FD_SET(connection_in, *readsetp);
                /*
                 * Read from stdin, unless we have seen EOF or have very much
                 * buffered data to send to the server.
                 */
                if (!stdin_eof && packet_not_very_much_data_to_write())
                        FD_SET(fileno(stdin), *readsetp);

                /* Select stdout/stderr if have data in buffer. */
                if (buffer_len(&stdout_buffer) > 0)
                        FD_SET(fileno(stdout), *writesetp);
                if (buffer_len(&stderr_buffer) > 0)
                        FD_SET(fileno(stderr), *writesetp);
        } else {
                /* channel_prepare_select could have closed the last channel */
                if (session_closed && !channel_still_open() &&
                    !packet_have_data_to_write()) {
                        /* clear mask since we did not call select() */
                        memset(*readsetp, 0, *nallocp);
                        memset(*writesetp, 0, *nallocp);
                        return;
                } else {
                        FD_SET(connection_in, *readsetp);
                }
        }

        /* Select server connection if have data to write to the server. */
        if (packet_have_data_to_write())
                FD_SET(connection_out, *writesetp);

        /*
         * Wait for something to happen.  This will suspend the process until
         * some selected descriptor can be read, written, or has some other
         * event pending, or a timeout expires.
         */

        timeout_secs = INT_MAX; /* we use INT_MAX to mean no timeout */
        if (options.server_alive_interval > 0 && compat20) {
                timeout_secs = options.server_alive_interval;
                server_alive_time = now + options.server_alive_interval;
        }
        if (options.rekey_interval > 0 && compat20 && !rekeying)
                timeout_secs = MIN(timeout_secs, packet_get_rekey_timeout());
        set_control_persist_exit_time();
        if (control_persist_exit_time > 0) {
                timeout_secs = MIN(timeout_secs,
                        control_persist_exit_time - now);
                if (timeout_secs < 0)
                        timeout_secs = 0;
        }
        if (minwait_secs != 0)
                timeout_secs = MIN(timeout_secs, (int)minwait_secs);
        if (timeout_secs == INT_MAX)
                tvp = NULL;
        else {
                tv.tv_sec = timeout_secs;
                tv.tv_usec = 0;
                tvp = &tv;
        }

        ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
        if (ret < 0) {
                char buf[100];

                /*
                 * We have to clear the select masks, because we return.
                 * We have to return, because the mainloop checks for the flags
                 * set by the signal handlers.
                 */
                memset(*readsetp, 0, *nallocp);
                memset(*writesetp, 0, *nallocp);

                if (errno == EINTR)
                        return;
                /* Note: we might still have data in the buffers. */
                snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
                buffer_append(&stderr_buffer, buf, strlen(buf));
                quit_pending = 1;
        } else if (ret == 0) {
                /*
                 * Timeout.  Could have been either keepalive or rekeying.
                 * Keepalive we check here, rekeying is checked in clientloop.
                 */
                if (server_alive_time != 0 && server_alive_time <= monotime())
                        server_alive_check();
        }

}

static void
client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr)
{
        /* Flush stdout and stderr buffers. */
        if (buffer_len(bout) > 0)
                atomicio(vwrite, fileno(stdout), buffer_ptr(bout),
                    buffer_len(bout));
        if (buffer_len(berr) > 0)
                atomicio(vwrite, fileno(stderr), buffer_ptr(berr),
                    buffer_len(berr));

        leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);

        /*
         * Free (and clear) the buffer to reduce the amount of data that gets
         * written to swap.
         */
        buffer_free(bin);
        buffer_free(bout);
        buffer_free(berr);

        /* Send the suspend signal to the program itself. */
        kill(getpid(), SIGTSTP);

        /* Reset window sizes in case they have changed */
        received_window_change_signal = 1;

        /* OK, we have been continued by the user. Reinitialize buffers. */
        buffer_init(bin);
        buffer_init(bout);
        buffer_init(berr);

        enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
}

static void
client_process_net_input(fd_set *readset)
{
        int len;
        char buf[SSH_IOBUFSZ];

        /*
         * Read input from the server, and add any such data to the buffer of
         * the packet subsystem.
         */
        if (FD_ISSET(connection_in, readset)) {
                /* Read as much as possible. */
                len = read(connection_in, buf, sizeof(buf));
                if (len == 0) {
                        /*
                         * Received EOF.  The remote host has closed the
                         * connection.
                         */
                        snprintf(buf, sizeof buf,
                            "Connection to %.300s closed by remote host.\r\n",
                            host);
                        buffer_append(&stderr_buffer, buf, strlen(buf));
                        quit_pending = 1;
                        return;
                }
                /*
                 * There is a kernel bug on Solaris that causes select to
                 * sometimes wake up even though there is no data available.
                 */
                if (len < 0 &&
                    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
                        len = 0;

                if (len < 0) {
                        /*
                         * An error has encountered.  Perhaps there is a
                         * network problem.
                         */
                        snprintf(buf, sizeof buf,
                            "Read from remote host %.300s: %.100s\r\n",
                            host, strerror(errno));
                        buffer_append(&stderr_buffer, buf, strlen(buf));
                        quit_pending = 1;
                        return;
                }
                packet_process_incoming(buf, len);
        }
}

static void
client_status_confirm(int type, Channel *c, void *ctx)
{
        struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
        char errmsg[256];
        int tochan;

        /*
         * If a TTY was explicitly requested, then a failure to allocate
         * one is fatal.
         */
        if (cr->action == CONFIRM_TTY &&
            (options.request_tty == REQUEST_TTY_FORCE ||
            options.request_tty == REQUEST_TTY_YES))
                cr->action = CONFIRM_CLOSE;

        /* XXX supress on mux _client_ quietmode */
        tochan = options.log_level >= SYSLOG_LEVEL_ERROR &&
            c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;

        if (type == SSH2_MSG_CHANNEL_SUCCESS) {
                debug2("%s request accepted on channel %d",
                    cr->request_type, c->self);
        } else if (type == SSH2_MSG_CHANNEL_FAILURE) {
                if (tochan) {
                        snprintf(errmsg, sizeof(errmsg),
                            "%s request failed\r\n", cr->request_type);
                } else {
                        snprintf(errmsg, sizeof(errmsg),
                            "%s request failed on channel %d",
                            cr->request_type, c->self);
                }
                /* If error occurred on primary session channel, then exit */
                if (cr->action == CONFIRM_CLOSE && c->self == session_ident)
                        fatal("%s", errmsg);
                /*
                 * If error occurred on mux client, append to
                 * their stderr.
                 */
                if (tochan) {
                        buffer_append(&c->extended, errmsg,
                            strlen(errmsg));
                } else
                        error("%s", errmsg);
                if (cr->action == CONFIRM_TTY) {
                        /*
                         * If a TTY allocation error occurred, then arrange
                         * for the correct TTY to leave raw mode.
                         */
                        if (c->self == session_ident)
                                leave_raw_mode(0);
                        else
                                mux_tty_alloc_failed(c);
                } else if (cr->action == CONFIRM_CLOSE) {
                        chan_read_failed(c);
                        chan_write_failed(c);
                }
        }
        free(cr);
}

static void
client_abandon_status_confirm(Channel *c, void *ctx)
{
        free(ctx);
}

void
client_expect_confirm(int id, const char *request,
    enum confirm_action action)
{
        struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr));

        cr->request_type = request;
        cr->action = action;

        channel_register_status_confirm(id, client_status_confirm,
            client_abandon_status_confirm, cr);
}

void
client_register_global_confirm(global_confirm_cb *cb, void *ctx)
{
        struct global_confirm *gc, *last_gc;

        /* Coalesce identical callbacks */
        last_gc = TAILQ_LAST(&global_confirms, global_confirms);
        if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) {
                if (++last_gc->ref_count >= INT_MAX)
                        fatal("%s: last_gc->ref_count = %d",
                            __func__, last_gc->ref_count);
                return;
        }

        gc = xcalloc(1, sizeof(*gc));
        gc->cb = cb;
        gc->ctx = ctx;
        gc->ref_count = 1;
        TAILQ_INSERT_TAIL(&global_confirms, gc, entry);
}

static void
process_cmdline(void)
{
        void (*handler)(int);
        char *s, *cmd;
        int ok, delete = 0, local = 0, remote = 0, dynamic = 0;
        struct Forward fwd;

        memset(&fwd, 0, sizeof(fwd));

        leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
        handler = signal(SIGINT, SIG_IGN);
        cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
        if (s == NULL)
                goto out;
        while (isspace((u_char)*s))
                s++;
        if (*s == '-')
                s++;    /* Skip cmdline '-', if any */
        if (*s == '\0')
                goto out;

        if (*s == 'h' || *s == 'H' || *s == '?') {
                logit("Commands:");
                logit("      -L[bind_address:]port:host:hostport    "
                    "Request local forward");
                logit("      -R[bind_address:]port:host:hostport    "
                    "Request remote forward");
                logit("      -D[bind_address:]port                  "
                    "Request dynamic forward");
                logit("      -KL[bind_address:]port                 "
                    "Cancel local forward");
                logit("      -KR[bind_address:]port                 "
                    "Cancel remote forward");
                logit("      -KD[bind_address:]port                 "
                    "Cancel dynamic forward");
                if (!options.permit_local_command)
                        goto out;
                logit("      !args                                  "
                    "Execute local command");
                goto out;
        }

        if (*s == '!' && options.permit_local_command) {
                s++;
                ssh_local_cmd(s);
                goto out;
        }

        if (*s == 'K') {
                delete = 1;
                s++;
        }
        if (*s == 'L')
                local = 1;
        else if (*s == 'R')
                remote = 1;
        else if (*s == 'D')
                dynamic = 1;
        else {
                logit("Invalid command.");
                goto out;
        }

        if (delete && !compat20) {
                logit("Not supported for SSH protocol version 1.");
                goto out;
        }

        while (isspace((u_char)*++s))
                ;

        /* XXX update list of forwards in options */
        if (delete) {
                /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */
                if (!parse_forward(&fwd, s, 1, 0)) {
                        logit("Bad forwarding close specification.");
                        goto out;
                }
                if (remote)
                        ok = channel_request_rforward_cancel(&fwd) == 0;
                else if (dynamic)
                        ok = channel_cancel_lport_listener(&fwd,
                            0, &options.fwd_opts) > 0;
                else
                        ok = channel_cancel_lport_listener(&fwd,
                            CHANNEL_CANCEL_PORT_STATIC,
                            &options.fwd_opts) > 0;
                if (!ok) {
                        logit("Unkown port forwarding.");
                        goto out;
                }
                logit("Canceled forwarding.");
        } else {
                if (!parse_forward(&fwd, s, dynamic, remote)) {
                        logit("Bad forwarding specification.");
                        goto out;
                }
                if (local || dynamic) {
                        if (!channel_setup_local_fwd_listener(&fwd,
                            &options.fwd_opts)) {
                                logit("Port forwarding failed.");
                                goto out;
                        }
                } else {
                        if (channel_request_remote_forwarding(&fwd) < 0) {
                                logit("Port forwarding failed.");
                                goto out;
                        }
                }
                logit("Forwarding port.");
        }

out:
        signal(SIGINT, handler);
        enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
        free(cmd);
        free(fwd.listen_host);
        free(fwd.listen_path);
        free(fwd.connect_host);
        free(fwd.connect_path);
}

/* reasons to suppress output of an escape command in help output */
#define SUPPRESS_NEVER          0       /* never suppress, always show */
#define SUPPRESS_PROTO1         1       /* don't show in protocol 1 sessions */
#define SUPPRESS_MUXCLIENT      2       /* don't show in mux client sessions */
#define SUPPRESS_MUXMASTER      4       /* don't show in mux master sessions */
#define SUPPRESS_SYSLOG         8       /* don't show when logging to syslog */
struct escape_help_text {
        const char *cmd;
        const char *text;
        unsigned int flags;
};
static struct escape_help_text esc_txt[] = {
    {".",  "terminate session", SUPPRESS_MUXMASTER},
    {".",  "terminate connection (and any multiplexed sessions)",
        SUPPRESS_MUXCLIENT},
    {"B",  "send a BREAK to the remote system", SUPPRESS_PROTO1},
    {"C",  "open a command line", SUPPRESS_MUXCLIENT},
    {"R",  "request rekey", SUPPRESS_PROTO1},
    {"V/v",  "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT},
    {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT},
    {"#",  "list forwarded connections", SUPPRESS_NEVER},
    {"&",  "background ssh (when waiting for connections to terminate)",
        SUPPRESS_MUXCLIENT},
    {"?", "this message", SUPPRESS_NEVER},
};

static void
print_escape_help(Buffer *b, int escape_char, int protocol2, int mux_client,
    int using_stderr)
{
        unsigned int i, suppress_flags;
        char string[1024];

        snprintf(string, sizeof string, "%c?\r\n"
            "Supported escape sequences:\r\n", escape_char);
        buffer_append(b, string, strlen(string));

        suppress_flags = (protocol2 ? 0 : SUPPRESS_PROTO1) |
            (mux_client ? SUPPRESS_MUXCLIENT : 0) |
            (mux_client ? 0 : SUPPRESS_MUXMASTER) |
            (using_stderr ? 0 : SUPPRESS_SYSLOG);

        for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) {
                if (esc_txt[i].flags & suppress_flags)
                        continue;
                snprintf(string, sizeof string, " %c%-3s - %s\r\n",
                    escape_char, esc_txt[i].cmd, esc_txt[i].text);
                buffer_append(b, string, strlen(string));
        }

        snprintf(string, sizeof string,
            " %c%c   - send the escape character by typing it twice\r\n"
            "(Note that escapes are only recognized immediately after "
            "newline.)\r\n", escape_char, escape_char);
        buffer_append(b, string, strlen(string));
}

/* 
 * Process the characters one by one, call with c==NULL for proto1 case.
 */
static int
process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
    char *buf, int len)
{
        char string[1024];
        pid_t pid;
        int bytes = 0;
        u_int i;
        u_char ch;
        char *s;
        int *escape_pendingp, escape_char;
        struct escape_filter_ctx *efc;

        if (c == NULL) {
                escape_pendingp = &escape_pending1;
                escape_char = escape_char1;
        } else {
                if (c->filter_ctx == NULL)
                        return 0;
                efc = (struct escape_filter_ctx *)c->filter_ctx;
                escape_pendingp = &efc->escape_pending;
                escape_char = efc->escape_char;
        }
        
        if (len <= 0)
                return (0);

        for (i = 0; i < (u_int)len; i++) {
                /* Get one character at a time. */
                ch = buf[i];

                if (*escape_pendingp) {
                        /* We have previously seen an escape character. */
                        /* Clear the flag now. */
                        *escape_pendingp = 0;

                        /* Process the escaped character. */
                        switch (ch) {
                        case '.':
                                /* Terminate the connection. */
                                snprintf(string, sizeof string, "%c.\r\n",
                                    escape_char);
                                buffer_append(berr, string, strlen(string));

                                if (c && c->ctl_chan != -1) {
                                        chan_read_failed(c);
                                        chan_write_failed(c);
                                        if (c->detach_user)
                                                c->detach_user(c->self, NULL);
                                        c->type = SSH_CHANNEL_ABANDONED;
                                        buffer_clear(&c->input);
                                        chan_ibuf_empty(c);
                                        return 0;
                                } else
                                        quit_pending = 1;
                                return -1;

                        case 'Z' - 64:
                                /* XXX support this for mux clients */
                                if (c && c->ctl_chan != -1) {
                                        char b[16];
 noescape:
                                        if (ch == 'Z' - 64)
                                                snprintf(b, sizeof b, "^Z");
                                        else
                                                snprintf(b, sizeof b, "%c", ch);
                                        snprintf(string, sizeof string,
                                            "%c%s escape not available to "
                                            "multiplexed sessions\r\n",
                                            escape_char, b);
                                        buffer_append(berr, string,
                                            strlen(string));
                                        continue;
                                }
                                /* Suspend the program. Inform the user */
                                snprintf(string, sizeof string,
                                    "%c^Z [suspend ssh]\r\n", escape_char);
                                buffer_append(berr, string, strlen(string));

                                /* Restore terminal modes and suspend. */
                                client_suspend_self(bin, bout, berr);

                                /* We have been continued. */
                                continue;

                        case 'B':
                                if (compat20) {
                                        snprintf(string, sizeof string,
                                            "%cB\r\n", escape_char);
                                        buffer_append(berr, string,
                                            strlen(string));
                                        channel_request_start(c->self,
                                            "break", 0);
                                        packet_put_int(1000);
                                        packet_send();
                                }
                                continue;

                        case 'R':
                                if (compat20) {
                                        if (datafellows & SSH_BUG_NOREKEY)
                                                logit("Server does not "
                                                    "support re-keying");
                                        else
                                                need_rekeying = 1;
                                }
                                continue;

                        case 'V':
                                /* FALLTHROUGH */
                        case 'v':
                                if (c && c->ctl_chan != -1)
                                        goto noescape;
                                if (!log_is_on_stderr()) {
                                        snprintf(string, sizeof string,
                                            "%c%c [Logging to syslog]\r\n",
                                             escape_char, ch);
                                        buffer_append(berr, string,
                                            strlen(string));
                                        continue;
                                }
                                if (ch == 'V' && options.log_level >
                                    SYSLOG_LEVEL_QUIET)
                                        log_change_level(--options.log_level);
                                if (ch == 'v' && options.log_level <
                                    SYSLOG_LEVEL_DEBUG3)
                                        log_change_level(++options.log_level);
                                snprintf(string, sizeof string,
                                    "%c%c [LogLevel %s]\r\n", escape_char, ch,
                                    log_level_name(options.log_level));
                                buffer_append(berr, string, strlen(string));
                                continue;

                        case '&':
                                if (c && c->ctl_chan != -1)
                                        goto noescape;
                                /*
                                 * Detach the program (continue to serve
                                 * connections, but put in background and no
                                 * more new connections).
                                 */
                                /* Restore tty modes. */
                                leave_raw_mode(
                                    options.request_tty == REQUEST_TTY_FORCE);

                                /* Stop listening for new connections. */
                                channel_stop_listening();

                                snprintf(string, sizeof string,
                                    "%c& [backgrounded]\n", escape_char);
                                buffer_append(berr, string, strlen(string));

                                /* Fork into background. */
                                pid = fork();
                                if (pid < 0) {
                                        error("fork: %.100s", strerror(errno));
                                        continue;
                                }
                                if (pid != 0) { /* This is the parent. */
                                        /* The parent just exits. */
                                        exit(0);
                                }
                                /* The child continues serving connections. */
                                if (compat20) {
                                        buffer_append(bin, "\004", 1);
                                        /* fake EOF on stdin */
                                        return -1;
                                } else if (!stdin_eof) {
                                        /*
                                         * Sending SSH_CMSG_EOF alone does not
                                         * always appear to be enough.  So we
                                         * try to send an EOF character first.
                                         */
                                        packet_start(SSH_CMSG_STDIN_DATA);
                                        packet_put_string("\004", 1);
                                        packet_send();
                                        /* Close stdin. */
                                        stdin_eof = 1;
                                        if (buffer_len(bin) == 0) {
                                                packet_start(SSH_CMSG_EOF);
                                                packet_send();
                                        }
                                }
                                continue;

                        case '?':
                                print_escape_help(berr, escape_char, compat20,
                                    (c && c->ctl_chan != -1),
                                    log_is_on_stderr());
                                continue;

                        case '#':
                                snprintf(string, sizeof string, "%c#\r\n",
                                    escape_char);
                                buffer_append(berr, string, strlen(string));
                                s = channel_open_message();
                                buffer_append(berr, s, strlen(s));
                                free(s);
                                continue;

                        case 'C':
                                if (c && c->ctl_chan != -1)
                                        goto noescape;
                                process_cmdline();
                                continue;

                        default:
                                if (ch != escape_char) {
                                        buffer_put_char(bin, escape_char);
                                        bytes++;
                                }
                                /* Escaped characters fall through here */
                                break;
                        }
                } else {
                        /*
                         * The previous character was not an escape char.
                         * Check if this is an escape.
                         */
                        if (last_was_cr && ch == escape_char) {
                                /*
                                 * It is. Set the flag and continue to
                                 * next character.
                                 */
                                *escape_pendingp = 1;
                                continue;
                        }
                }

                /*
                 * Normal character.  Record whether it was a newline,
                 * and append it to the buffer.
                 */
                last_was_cr = (ch == '\r' || ch == '\n');
                buffer_put_char(bin, ch);
                bytes++;
        }
        return bytes;
}

static void
client_process_input(fd_set *readset)
{
        int len;
        char buf[SSH_IOBUFSZ];

        /* Read input from stdin. */
        if (FD_ISSET(fileno(stdin), readset)) {
                /* Read as much as possible. */
                len = read(fileno(stdin), buf, sizeof(buf));
                if (len < 0 &&
                    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
                        return;         /* we'll try again later */
                if (len <= 0) {
                        /*
                         * Received EOF or error.  They are treated
                         * similarly, except that an error message is printed
                         * if it was an error condition.
                         */
                        if (len < 0) {
                                snprintf(buf, sizeof buf, "read: %.100s\r\n",
                                    strerror(errno));
                                buffer_append(&stderr_buffer, buf, strlen(buf));
                        }
                        /* Mark that we have seen EOF. */
                        stdin_eof = 1;
                        /*
                         * Send an EOF message to the server unless there is
                         * data in the buffer.  If there is data in the
                         * buffer, no message will be sent now.  Code
                         * elsewhere will send the EOF when the buffer
                         * becomes empty if stdin_eof is set.
                         */
                        if (buffer_len(&stdin_buffer) == 0) {
                                packet_start(SSH_CMSG_EOF);
                                packet_send();
                        }
                } else if (escape_char1 == SSH_ESCAPECHAR_NONE) {
                        /*
                         * Normal successful read, and no escape character.
                         * Just append the data to buffer.
                         */
                        buffer_append(&stdin_buffer, buf, len);
                } else {
                        /*
                         * Normal, successful read.  But we have an escape
                         * character and have to process the characters one
                         * by one.
                         */
                        if (process_escapes(NULL, &stdin_buffer,
                            &stdout_buffer, &stderr_buffer, buf, len) == -1)
                                return;
                }
        }
}

static void
client_process_output(fd_set *writeset)
{
        int len;
        char buf[100];

        /* Write buffered output to stdout. */
        if (FD_ISSET(fileno(stdout), writeset)) {
                /* Write as much data as possible. */
                len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
                    buffer_len(&stdout_buffer));
                if (len <= 0) {
                        if (errno == EINTR || errno == EAGAIN ||
                            errno == EWOULDBLOCK)
                                len = 0;
                        else {
                                /*
                                 * An error or EOF was encountered.  Put an
                                 * error message to stderr buffer.
                                 */
                                snprintf(buf, sizeof buf,
                                    "write stdout: %.50s\r\n", strerror(errno));
                                buffer_append(&stderr_buffer, buf, strlen(buf));
                                quit_pending = 1;
                                return;
                        }
                }
                /* Consume printed data from the buffer. */
                buffer_consume(&stdout_buffer, len);
        }
        /* Write buffered output to stderr. */
        if (FD_ISSET(fileno(stderr), writeset)) {
                /* Write as much data as possible. */
                len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
                    buffer_len(&stderr_buffer));
                if (len <= 0) {
                        if (errno == EINTR || errno == EAGAIN ||
                            errno == EWOULDBLOCK)
                                len = 0;
                        else {
                                /*
                                 * EOF or error, but can't even print
                                 * error message.
                                 */
                                quit_pending = 1;
                                return;
                        }
                }
                /* Consume printed characters from the buffer. */
                buffer_consume(&stderr_buffer, len);
        }
}

/*
 * Get packets from the connection input buffer, and process them as long as
 * there are packets available.
 *
 * Any unknown packets received during the actual
 * session cause the session to terminate.  This is
 * intended to make debugging easier since no
 * confirmations are sent.  Any compatible protocol
 * extensions must be negotiated during the
 * preparatory phase.
 */

static void
client_process_buffered_input_packets(void)
{
        dispatch_run(DISPATCH_NONBLOCK, &quit_pending, active_state);
}

/* scan buf[] for '~' before sending data to the peer */

/* Helper: allocate a new escape_filter_ctx and fill in its escape char */
void *
client_new_escape_filter_ctx(int escape_char)
{
        struct escape_filter_ctx *ret;

        ret = xcalloc(1, sizeof(*ret));
        ret->escape_pending = 0;
        ret->escape_char = escape_char;
        return (void *)ret;
}

/* Free the escape filter context on channel free */
void
client_filter_cleanup(int cid, void *ctx)
{
        free(ctx);
}

int
client_simple_escape_filter(Channel *c, char *buf, int len)
{
        if (c->extended_usage != CHAN_EXTENDED_WRITE)
                return 0;

        return process_escapes(c, &c->input, &c->output, &c->extended,
            buf, len);
}

static void
client_channel_closed(int id, void *arg)
{
        channel_cancel_cleanup(id);
        session_closed = 1;
        leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
}

/*
 * Implements the interactive session with the server.  This is called after
 * the user has been authenticated, and a command has been started on the
 * remote host.  If escape_char != SSH_ESCAPECHAR_NONE, it is the character
 * used as an escape character for terminating or suspending the session.
 */

int
client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
{
        fd_set *readset = NULL, *writeset = NULL;
        double start_time, total_time;
        int r, max_fd = 0, max_fd2 = 0, len;
        u_int64_t ibytes, obytes;
        u_int nalloc = 0;
        char buf[100];

        debug("Entering interactive session.");

        if (options.control_master &&
            !option_clear_or_none(options.control_path)) {
                debug("pledge: id");
                if (pledge("stdio rpath wpath cpath unix inet dns recvfd proc exec id tty",
                    NULL) == -1)
                        fatal("%s pledge(): %s", __func__, strerror(errno));

        } else if (options.forward_x11 || options.permit_local_command) {
                debug("pledge: exec");
                if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty",
                    NULL) == -1)
                        fatal("%s pledge(): %s", __func__, strerror(errno));

        } else if (options.update_hostkeys) {
                debug("pledge: filesystem full");
                if (pledge("stdio rpath wpath cpath unix inet dns proc tty",
                    NULL) == -1)
                        fatal("%s pledge(): %s", __func__, strerror(errno));

        } else if (!option_clear_or_none(options.proxy_command) ||
            fork_after_authentication_flag) {
                debug("pledge: proc");
                if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1)
                        fatal("%s pledge(): %s", __func__, strerror(errno));

        } else {
                debug("pledge: network");
                if (pledge("stdio unix inet dns tty", NULL) == -1)
                        fatal("%s pledge(): %s", __func__, strerror(errno));
        }

        start_time = get_current_time();

        /* Initialize variables. */
        escape_pending1 = 0;
        last_was_cr = 1;
        exit_status = -1;
        stdin_eof = 0;
        buffer_high = 64 * 1024;
        connection_in = packet_get_connection_in();
        connection_out = packet_get_connection_out();
        max_fd = MAX(connection_in, connection_out);

        if (!compat20) {
                /* enable nonblocking unless tty */
                if (!isatty(fileno(stdin)))
                        set_nonblock(fileno(stdin));
                if (!isatty(fileno(stdout)))
                        set_nonblock(fileno(stdout));
                if (!isatty(fileno(stderr)))
                        set_nonblock(fileno(stderr));
                max_fd = MAX(max_fd, fileno(stdin));
                max_fd = MAX(max_fd, fileno(stdout));
                max_fd = MAX(max_fd, fileno(stderr));
        }
        quit_pending = 0;
        escape_char1 = escape_char_arg;

        /* Initialize buffers. */
        buffer_init(&stdin_buffer);
        buffer_init(&stdout_buffer);
        buffer_init(&stderr_buffer);

        client_init_dispatch();

        /*
         * Set signal handlers, (e.g. to restore non-blocking mode)
         * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
         */
        if (signal(SIGHUP, SIG_IGN) != SIG_IGN)
                signal(SIGHUP, signal_handler);
        if (signal(SIGINT, SIG_IGN) != SIG_IGN)
                signal(SIGINT, signal_handler);
        if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
                signal(SIGQUIT, signal_handler);
        if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
                signal(SIGTERM, signal_handler);
        signal(SIGWINCH, window_change_handler);

        if (have_pty)
                enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);

        if (compat20) {
                session_ident = ssh2_chan_id;
                if (session_ident != -1) {
                        if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
                                channel_register_filter(session_ident,
                                    client_simple_escape_filter, NULL,
                                    client_filter_cleanup,
                                    client_new_escape_filter_ctx(
                                    escape_char_arg));
                        }
                        channel_register_cleanup(session_ident,
                            client_channel_closed, 0);
                }
        } else {
                /* Check if we should immediately send eof on stdin. */
                client_check_initial_eof_on_stdin();
        }

        /* Main loop of the client for the interactive session mode. */
        while (!quit_pending) {

                /* Process buffered packets sent by the server. */
                client_process_buffered_input_packets();

                if (compat20 && session_closed && !channel_still_open())
                        break;

                if (ssh_packet_is_rekeying(active_state)) {
                        debug("rekeying in progress");
                } else if (need_rekeying) {
                        /* manual rekey request */
                        debug("need rekeying");
                        if ((r = kex_start_rekex(active_state)) != 0)
                                fatal("%s: kex_start_rekex: %s", __func__,
                                    ssh_err(r));
                        need_rekeying = 0;
                } else {
                        /*
                         * Make packets of buffered stdin data, and buffer
                         * them for sending to the server.
                         */
                        if (!compat20)
                                client_make_packets_from_stdin_data();

                        /*
                         * Make packets from buffered channel data, and
                         * enqueue them for sending to the server.
                         */
                        if (packet_not_very_much_data_to_write())
                                channel_output_poll();

                        /*
                         * Check if the window size has changed, and buffer a
                         * message about it to the server if so.
                         */
                        client_check_window_change();

                        if (quit_pending)
                                break;
                }
                /*
                 * Wait until we have something to do (something becomes
                 * available on one of the descriptors).
                 */
                max_fd2 = max_fd;
                client_wait_until_can_do_something(&readset, &writeset,
                    &max_fd2, &nalloc, ssh_packet_is_rekeying(active_state));

                if (quit_pending)
                        break;

                /* Do channel operations unless rekeying in progress. */
                if (!ssh_packet_is_rekeying(active_state))
                        channel_after_select(readset, writeset);

                /* Buffer input from the connection.  */
                client_process_net_input(readset);

                if (quit_pending)
                        break;

                if (!compat20) {
                        /* Buffer data from stdin */
                        client_process_input(readset);
                        /*
                         * Process output to stdout and stderr.  Output to
                         * the connection is processed elsewhere (above).
                         */
                        client_process_output(writeset);
                }

                /*
                 * Send as much buffered packet data as possible to the
                 * sender.
                 */
                if (FD_ISSET(connection_out, writeset))
                        packet_write_poll();

                /*
                 * If we are a backgrounded control master, and the
                 * timeout has expired without any active client
                 * connections, then quit.
                 */
                if (control_persist_exit_time > 0) {
                        if (monotime() >= control_persist_exit_time) {
                                debug("ControlPersist timeout expired");
                                break;
                        }
                }
        }
        free(readset);
        free(writeset);

        /* Terminate the session. */

        /* Stop watching for window change. */
        signal(SIGWINCH, SIG_DFL);

        if (compat20) {
                packet_start(SSH2_MSG_DISCONNECT);
                packet_put_int(SSH2_DISCONNECT_BY_APPLICATION);
                packet_put_cstring("disconnected by user");
                packet_put_cstring(""); /* language tag */
                packet_send();
                packet_write_wait();
        }

        channel_free_all();

        if (have_pty)
                leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);

        /* restore blocking io */
        if (!isatty(fileno(stdin)))
                unset_nonblock(fileno(stdin));
        if (!isatty(fileno(stdout)))
                unset_nonblock(fileno(stdout));
        if (!isatty(fileno(stderr)))
                unset_nonblock(fileno(stderr));

        /*
         * If there was no shell or command requested, there will be no remote
         * exit status to be returned.  In that case, clear error code if the
         * connection was deliberately terminated at this end.
         */
        if (no_shell_flag && received_signal == SIGTERM) {
                received_signal = 0;
                exit_status = 0;
        }

        if (received_signal)
                fatal("Killed by signal %d.", (int) received_signal);

        /*
         * In interactive mode (with pseudo tty) display a message indicating
         * that the connection has been closed.
         */
        if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
                snprintf(buf, sizeof buf,
                    "Connection to %.64s closed.\r\n", host);
                buffer_append(&stderr_buffer, buf, strlen(buf));
        }

        /* Output any buffered data for stdout. */
        if (buffer_len(&stdout_buffer) > 0) {
                len = atomicio(vwrite, fileno(stdout),
                    buffer_ptr(&stdout_buffer), buffer_len(&stdout_buffer));
                if (len < 0 || (u_int)len != buffer_len(&stdout_buffer))
                        error("Write failed flushing stdout buffer.");
                else
                        buffer_consume(&stdout_buffer, len);
        }

        /* Output any buffered data for stderr. */
        if (buffer_len(&stderr_buffer) > 0) {
                len = atomicio(vwrite, fileno(stderr),
                    buffer_ptr(&stderr_buffer), buffer_len(&stderr_buffer));
                if (len < 0 || (u_int)len != buffer_len(&stderr_buffer))
                        error("Write failed flushing stderr buffer.");
                else
                        buffer_consume(&stderr_buffer, len);
        }

        /* Clear and free any buffers. */
        explicit_bzero(buf, sizeof(buf));
        buffer_free(&stdin_buffer);
        buffer_free(&stdout_buffer);
        buffer_free(&stderr_buffer);

        /* Report bytes transferred, and transfer rates. */
        total_time = get_current_time() - start_time;
        packet_get_bytes(&ibytes, &obytes);
        verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds",
            (unsigned long long)obytes, (unsigned long long)ibytes, total_time);
        if (total_time > 0)
                verbose("Bytes per second: sent %.1f, received %.1f",
                    obytes / total_time, ibytes / total_time);
        /* Return the exit status of the program. */
        debug("Exit status %d", exit_status);
        return exit_status;
}

/*********/

static int
client_input_stdout_data(int type, u_int32_t seq, void *ctxt)
{
        u_int data_len;
        char *data = packet_get_string(&data_len);
        packet_check_eom();
        buffer_append(&stdout_buffer, data, data_len);
        explicit_bzero(data, data_len);
        free(data);
        return 0;
}
static int
client_input_stderr_data(int type, u_int32_t seq, void *ctxt)
{
        u_int data_len;
        char *data = packet_get_string(&data_len);
        packet_check_eom();
        buffer_append(&stderr_buffer, data, data_len);
        explicit_bzero(data, data_len);
        free(data);
        return 0;
}
static int
client_input_exit_status(int type, u_int32_t seq, void *ctxt)
{
        exit_status = packet_get_int();
        packet_check_eom();
        /* Acknowledge the exit. */
        packet_start(SSH_CMSG_EXIT_CONFIRMATION);
        packet_send();
        /*
         * Must wait for packet to be sent since we are
         * exiting the loop.
         */
        packet_write_wait();
        /* Flag that we want to exit. */
        quit_pending = 1;
        return 0;
}

static int
client_input_agent_open(int type, u_int32_t seq, void *ctxt)
{
        Channel *c = NULL;
        int r, remote_id, sock;

        /* Read the remote channel number from the message. */
        remote_id = packet_get_int();
        packet_check_eom();

        /*
         * Get a connection to the local authentication agent (this may again
         * get forwarded).
         */
        if ((r = ssh_get_authentication_socket(&sock)) != 0 &&
            r != SSH_ERR_AGENT_NOT_PRESENT)
                debug("%s: ssh_get_authentication_socket: %s",
                    __func__, ssh_err(r));


        /*
         * If we could not connect the agent, send an error message back to
         * the server. This should never happen unless the agent dies,
         * because authentication forwarding is only enabled if we have an
         * agent.
         */
        if (sock >= 0) {
                c = channel_new("", SSH_CHANNEL_OPEN, sock, sock,
                    -1, 0, 0, 0, "authentication agent connection", 1);
                c->remote_id = remote_id;
                c->force_drain = 1;
        }
        if (c == NULL) {
                packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
                packet_put_int(remote_id);
        } else {
                /* Send a confirmation to the remote host. */
                debug("Forwarding authentication connection.");
                packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
                packet_put_int(remote_id);
                packet_put_int(c->self);
        }
        packet_send();
        return 0;
}

static Channel *
client_request_forwarded_tcpip(const char *request_type, int rchan)
{
        Channel *c = NULL;
        char *listen_address, *originator_address;
        u_short listen_port, originator_port;

        /* Get rest of the packet */
        listen_address = packet_get_string(NULL);
        listen_port = packet_get_int();
        originator_address = packet_get_string(NULL);
        originator_port = packet_get_int();
        packet_check_eom();

        debug("%s: listen %s port %d, originator %s port %d", __func__,
            listen_address, listen_port, originator_address, originator_port);

        c = channel_connect_by_listen_address(listen_address, listen_port,
            "forwarded-tcpip", originator_address);

        free(originator_address);
        free(listen_address);
        return c;
}

static Channel *
client_request_forwarded_streamlocal(const char *request_type, int rchan)
{
        Channel *c = NULL;
        char *listen_path;

        /* Get the remote path. */
        listen_path = packet_get_string(NULL);
        /* XXX: Skip reserved field for now. */
        if (packet_get_string_ptr(NULL) == NULL)
                fatal("%s: packet_get_string_ptr failed", __func__);
        packet_check_eom();

        debug("%s: %s", __func__, listen_path);

        c = channel_connect_by_listen_path(listen_path,
            "forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
        free(listen_path);
        return c;
}

static Channel *
client_request_x11(const char *request_type, int rchan)
{
        Channel *c = NULL;
        char *originator;
        u_short originator_port;
        int sock;

        if (!options.forward_x11) {
                error("Warning: ssh server tried X11 forwarding.");
                error("Warning: this is probably a break-in attempt by a "
                    "malicious server.");
                return NULL;
        }
        if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) {
                verbose("Rejected X11 connection after ForwardX11Timeout "
                    "expired");
                return NULL;
        }
        originator = packet_get_string(NULL);
        if (datafellows & SSH_BUG_X11FWD) {
                debug2("buggy server: x11 request w/o originator_port");
                originator_port = 0;
        } else {
                originator_port = packet_get_int();
        }
        packet_check_eom();
        /* XXX check permission */
        debug("client_request_x11: request from %s %d", originator,
            originator_port);
        free(originator);
        sock = x11_connect_display();
        if (sock < 0)
                return NULL;
        c = channel_new("x11",
            SSH_CHANNEL_X11_OPEN, sock, sock, -1,
            CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
        c->force_drain = 1;
        return c;
}

static Channel *
client_request_agent(const char *request_type, int rchan)
{
        Channel *c = NULL;
        int r, sock;

        if (!options.forward_agent) {
                error("Warning: ssh server tried agent forwarding.");
                error("Warning: this is probably a break-in attempt by a "
                    "malicious server.");
                return NULL;
        }
        if ((r = ssh_get_authentication_socket(&sock)) != 0) {
                if (r != SSH_ERR_AGENT_NOT_PRESENT)
                        debug("%s: ssh_get_authentication_socket: %s",
                            __func__, ssh_err(r));
                return NULL;
        }
        c = channel_new("authentication agent connection",
            SSH_CHANNEL_OPEN, sock, sock, -1,
            CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
            "authentication agent connection", 1);
        c->force_drain = 1;
        return c;
}

int
client_request_tun_fwd(int tun_mode, int local_tun, int remote_tun)
{
        Channel *c;
        int fd;

        if (tun_mode == SSH_TUNMODE_NO)
                return 0;

        if (!compat20) {
                error("Tunnel forwarding is not supported for protocol 1");
                return -1;
        }

        debug("Requesting tun unit %d in mode %d", local_tun, tun_mode);

        /* Open local tunnel device */
        if ((fd = tun_open(local_tun, tun_mode)) == -1) {
                error("Tunnel device open failed.");
                return -1;
        }

        c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
            CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
        c->datagram = 1;

#if defined(SSH_TUN_FILTER)
        if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
                channel_register_filter(c->self, sys_tun_infilter,
                    sys_tun_outfilter, NULL, NULL);
#endif

        packet_start(SSH2_MSG_CHANNEL_OPEN);
        packet_put_cstring("tun@openssh.com");
        packet_put_int(c->self);
        packet_put_int(c->local_window_max);
        packet_put_int(c->local_maxpacket);
        packet_put_int(tun_mode);
        packet_put_int(remote_tun);
        packet_send();

        return 0;
}

/* XXXX move to generic input handler */
static int
client_input_channel_open(int type, u_int32_t seq, void *ctxt)
{
        Channel *c = NULL;
        char *ctype;
        int rchan;
        u_int rmaxpack, rwindow, len;

        ctype = packet_get_string(&len);
        rchan = packet_get_int();
        rwindow = packet_get_int();
        rmaxpack = packet_get_int();

        debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
            ctype, rchan, rwindow, rmaxpack);

        if (strcmp(ctype, "forwarded-tcpip") == 0) {
                c = client_request_forwarded_tcpip(ctype, rchan);
        } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
                c = client_request_forwarded_streamlocal(ctype, rchan);
        } else if (strcmp(ctype, "x11") == 0) {
                c = client_request_x11(ctype, rchan);
        } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
                c = client_request_agent(ctype, rchan);
        }
/* XXX duplicate : */
        if (c != NULL) {
                debug("confirm %s", ctype);
                c->remote_id = rchan;
                c->remote_window = rwindow;
                c->remote_maxpacket = rmaxpack;
                if (c->type != SSH_CHANNEL_CONNECTING) {
                        packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
                        packet_put_int(c->remote_id);
                        packet_put_int(c->self);
                        packet_put_int(c->local_window);
                        packet_put_int(c->local_maxpacket);
                        packet_send();
                }
        } else {
                debug("failure %s", ctype);
                packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
                packet_put_int(rchan);
                packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
                if (!(datafellows & SSH_BUG_OPENFAILURE)) {
                        packet_put_cstring("open failed");
                        packet_put_cstring("");
                }
                packet_send();
        }
        free(ctype);
        return 0;
}

static int
client_input_channel_req(int type, u_int32_t seq, void *ctxt)
{
        Channel *c = NULL;
        int exitval, id, reply, success = 0;
        char *rtype;

        id = packet_get_int();
        rtype = packet_get_string(NULL);
        reply = packet_get_char();

        debug("client_input_channel_req: channel %d rtype %s reply %d",
            id, rtype, reply);

        if (id == -1) {
                error("client_input_channel_req: request for channel -1");
        } else if ((c = channel_lookup(id)) == NULL) {
                error("client_input_channel_req: channel %d: "
                    "unknown channel", id);
        } else if (strcmp(rtype, "eow@openssh.com") == 0) {
                packet_check_eom();
                chan_rcvd_eow(c);
        } else if (strcmp(rtype, "exit-status") == 0) {
                exitval = packet_get_int();
                if (c->ctl_chan != -1) {
                        mux_exit_message(c, exitval);
                        success = 1;
                } else if (id == session_ident) {
                        /* Record exit value of local session */
                        success = 1;
                        exit_status = exitval;
                } else {
                        /* Probably for a mux channel that has already closed */
                        debug("%s: no sink for exit-status on channel %d",
                            __func__, id);
                }
                packet_check_eom();
        }
        if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
                packet_start(success ?
                    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
                packet_put_int(c->remote_id);
                packet_send();
        }
        free(rtype);
        return 0;
}

struct hostkeys_update_ctx {
        /* The hostname and (optionally) IP address string for the server */
        char *host_str, *ip_str;

        /*
         * Keys received from the server and a flag for each indicating
         * whether they already exist in known_hosts.
         * keys_seen is filled in by hostkeys_find() and later (for new
         * keys) by client_global_hostkeys_private_confirm().
         */
        struct sshkey **keys;
        int *keys_seen;
        size_t nkeys;

        size_t nnew;

        /*
         * Keys that are in known_hosts, but were not present in the update
         * from the server (i.e. scheduled to be deleted).
         * Filled in by hostkeys_find().
         */
        struct sshkey **old_keys;
        size_t nold;
};

static void
hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx)
{
        size_t i;

        if (ctx == NULL)
                return;
        for (i = 0; i < ctx->nkeys; i++)
                sshkey_free(ctx->keys[i]);
        free(ctx->keys);
        free(ctx->keys_seen);
        for (i = 0; i < ctx->nold; i++)
                sshkey_free(ctx->old_keys[i]);
        free(ctx->old_keys);
        free(ctx->host_str);
        free(ctx->ip_str);
        free(ctx);
}

static int
hostkeys_find(struct hostkey_foreach_line *l, void *_ctx)
{
        struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
        size_t i;
        struct sshkey **tmp;

        if (l->status != HKF_STATUS_MATCHED || l->key == NULL ||
            l->key->type == KEY_RSA1)
                return 0;

        /* Mark off keys we've already seen for this host */
        for (i = 0; i < ctx->nkeys; i++) {
                if (sshkey_equal(l->key, ctx->keys[i])) {
                        debug3("%s: found %s key at %s:%ld", __func__,
                            sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
                        ctx->keys_seen[i] = 1;
                        return 0;
                }
        }
        /* This line contained a key that not offered by the server */
        debug3("%s: deprecated %s key at %s:%ld", __func__,
            sshkey_ssh_name(l->key), l->path, l->linenum);
        if ((tmp = reallocarray(ctx->old_keys, ctx->nold + 1,
            sizeof(*ctx->old_keys))) == NULL)
                fatal("%s: reallocarray failed nold = %zu",
                    __func__, ctx->nold);
        ctx->old_keys = tmp;
        ctx->old_keys[ctx->nold++] = l->key;
        l->key = NULL;

        return 0;
}

static void
update_known_hosts(struct hostkeys_update_ctx *ctx)
{
        int r, was_raw = 0;
        int loglevel = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK ?
            SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
        char *fp, *response;
        size_t i;

        for (i = 0; i < ctx->nkeys; i++) {
                if (ctx->keys_seen[i] != 2)
                        continue;
                if ((fp = sshkey_fingerprint(ctx->keys[i],
                    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
                        fatal("%s: sshkey_fingerprint failed", __func__);
                do_log2(loglevel, "Learned new hostkey: %s %s",
                    sshkey_type(ctx->keys[i]), fp);
                free(fp);
        }
        for (i = 0; i < ctx->nold; i++) {
                if ((fp = sshkey_fingerprint(ctx->old_keys[i],
                    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
                        fatal("%s: sshkey_fingerprint failed", __func__);
                do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
                    sshkey_type(ctx->old_keys[i]), fp);
                free(fp);
        }
        if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
                if (get_saved_tio() != NULL) {
                        leave_raw_mode(1);
                        was_raw = 1;
                }
                response = NULL;
                for (i = 0; !quit_pending && i < 3; i++) {
                        free(response);
                        response = read_passphrase("Accept updated hostkeys? "
                            "(yes/no): ", RP_ECHO);
                        if (strcasecmp(response, "yes") == 0)
                                break;
                        else if (quit_pending || response == NULL ||
                            strcasecmp(response, "no") == 0) {
                                options.update_hostkeys = 0;
                                break;
                        } else {
                                do_log2(loglevel, "Please enter "
                                    "\"yes\" or \"no\"");
                        }
                }
                if (quit_pending || i >= 3 || response == NULL)
                        options.update_hostkeys = 0;
                free(response);
                if (was_raw)
                        enter_raw_mode(1);
        }

        /*
         * Now that all the keys are verified, we can go ahead and replace
         * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
         * cancel the operation).
         */
        if (options.update_hostkeys != 0 &&
            (r = hostfile_replace_entries(options.user_hostfiles[0],
            ctx->host_str, ctx->ip_str, ctx->keys, ctx->nkeys,
            options.hash_known_hosts, 0,
            options.fingerprint_hash)) != 0)
                error("%s: hostfile_replace_entries failed: %s",
                    __func__, ssh_err(r));
}

static void
client_global_hostkeys_private_confirm(int type, u_int32_t seq, void *_ctx)
{
        struct ssh *ssh = active_state; /* XXX */
        struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
        size_t i, ndone;
        struct sshbuf *signdata;
        int r;
        const u_char *sig;
        size_t siglen;

        if (ctx->nnew == 0)
                fatal("%s: ctx->nnew == 0", __func__); /* sanity */
        if (type != SSH2_MSG_REQUEST_SUCCESS) {
                error("Server failed to confirm ownership of "
                    "private host keys");
                hostkeys_update_ctx_free(ctx);
                return;
        }
        if ((signdata = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        /* Don't want to accidentally accept an unbound signature */
        if (ssh->kex->session_id_len == 0)
                fatal("%s: ssh->kex->session_id_len == 0", __func__);
        /*
         * Expect a signature for each of the ctx->nnew private keys we
         * haven't seen before. They will be in the same order as the
         * ctx->keys where the corresponding ctx->keys_seen[i] == 0.
         */
        for (ndone = i = 0; i < ctx->nkeys; i++) {
                if (ctx->keys_seen[i])
                        continue;
                /* Prepare data to be signed: session ID, unique string, key */
                sshbuf_reset(signdata);
                if ( (r = sshbuf_put_cstring(signdata,
                    "hostkeys-prove-00@openssh.com")) != 0 ||
                    (r = sshbuf_put_string(signdata, ssh->kex->session_id,
                    ssh->kex->session_id_len)) != 0 ||
                    (r = sshkey_puts(ctx->keys[i], signdata)) != 0)
                        fatal("%s: failed to prepare signature: %s",
                            __func__, ssh_err(r));
                /* Extract and verify signature */
                if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
                        error("%s: couldn't parse message: %s",
                            __func__, ssh_err(r));
                        goto out;
                }
                if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
                    sshbuf_ptr(signdata), sshbuf_len(signdata), 0)) != 0) {
                        error("%s: server gave bad signature for %s key %zu",
                            __func__, sshkey_type(ctx->keys[i]), i);
                        goto out;
                }
                /* Key is good. Mark it as 'seen' */
                ctx->keys_seen[i] = 2;
                ndone++;
        }
        if (ndone != ctx->nnew)
                fatal("%s: ndone != ctx->nnew (%zu / %zu)", __func__,
                    ndone, ctx->nnew);  /* Shouldn't happen */
        ssh_packet_check_eom(ssh);

        /* Make the edits to known_hosts */
        update_known_hosts(ctx);
 out:
        hostkeys_update_ctx_free(ctx);
}

/*
 * Handle hostkeys-00@openssh.com global request to inform the client of all
 * the server's hostkeys. The keys are checked against the user's
 * HostkeyAlgorithms preference before they are accepted.
 */
static int
client_input_hostkeys(void)
{
        struct ssh *ssh = active_state; /* XXX */
        const u_char *blob = NULL;
        size_t i, len = 0;
        struct sshbuf *buf = NULL;
        struct sshkey *key = NULL, **tmp;
        int r;
        char *fp;
        static int hostkeys_seen = 0; /* XXX use struct ssh */
        extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */
        struct hostkeys_update_ctx *ctx = NULL;

        if (hostkeys_seen)
                fatal("%s: server already sent hostkeys", __func__);
        if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK &&
            options.batch_mode)
                return 1; /* won't ask in batchmode, so don't even try */
        if (!options.update_hostkeys || options.num_user_hostfiles <= 0)
                return 1;

        ctx = xcalloc(1, sizeof(*ctx));
        while (ssh_packet_remaining(ssh) > 0) {
                sshkey_free(key);
                key = NULL;
                if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) {
                        error("%s: couldn't parse message: %s",
                            __func__, ssh_err(r));
                        goto out;
                }
                if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
                        error("%s: parse key: %s", __func__, ssh_err(r));
                        goto out;
                }
                fp = sshkey_fingerprint(key, options.fingerprint_hash,
                    SSH_FP_DEFAULT);
                debug3("%s: received %s key %s", __func__,
                    sshkey_type(key), fp);
                free(fp);

                /* Check that the key is accepted in HostkeyAlgorithms */
                if (match_pattern_list(sshkey_ssh_name(key),
                    options.hostkeyalgorithms ? options.hostkeyalgorithms :
                    KEX_DEFAULT_PK_ALG, 0) != 1) {
                        debug3("%s: %s key not permitted by HostkeyAlgorithms",
                            __func__, sshkey_ssh_name(key));
                        continue;
                }
                /* Skip certs */
                if (sshkey_is_cert(key)) {
                        debug3("%s: %s key is a certificate; skipping",
                            __func__, sshkey_ssh_name(key));
                        continue;
                }
                /* Ensure keys are unique */
                for (i = 0; i < ctx->nkeys; i++) {
                        if (sshkey_equal(key, ctx->keys[i])) {
                                error("%s: received duplicated %s host key",
                                    __func__, sshkey_ssh_name(key));
                                goto out;
                        }
                }
                /* Key is good, record it */
                if ((tmp = reallocarray(ctx->keys, ctx->nkeys + 1,
                    sizeof(*ctx->keys))) == NULL)
                        fatal("%s: reallocarray failed nkeys = %zu",
                            __func__, ctx->nkeys);
                ctx->keys = tmp;
                ctx->keys[ctx->nkeys++] = key;
                key = NULL;
        }

        if (ctx->nkeys == 0) {
                debug("%s: server sent no hostkeys", __func__);
                goto out;
        }

        if ((ctx->keys_seen = calloc(ctx->nkeys,
            sizeof(*ctx->keys_seen))) == NULL)
                fatal("%s: calloc failed", __func__);

        get_hostfile_hostname_ipaddr(host,
            options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL,
            options.port, &ctx->host_str,
            options.check_host_ip ? &ctx->ip_str : NULL);

        /* Find which keys we already know about. */
        if ((r = hostkeys_foreach(options.user_hostfiles[0], hostkeys_find,
            ctx, ctx->host_str, ctx->ip_str,
            HKF_WANT_PARSE_KEY|HKF_WANT_MATCH)) != 0) {
                error("%s: hostkeys_foreach failed: %s", __func__, ssh_err(r));
                goto out;
        }

        /* Figure out if we have any new keys to add */
        ctx->nnew = 0;
        for (i = 0; i < ctx->nkeys; i++) {
                if (!ctx->keys_seen[i])
                        ctx->nnew++;
        }

        debug3("%s: %zu keys from server: %zu new, %zu retained. %zu to remove",
            __func__, ctx->nkeys, ctx->nnew, ctx->nkeys - ctx->nnew, ctx->nold);

        if (ctx->nnew == 0 && ctx->nold != 0) {
                /* We have some keys to remove. Just do it. */
                update_known_hosts(ctx);
        } else if (ctx->nnew != 0) {
                /*
                 * We have received hitherto-unseen keys from the server.
                 * Ask the server to confirm ownership of the private halves.
                 */
                debug3("%s: asking server to prove ownership for %zu keys",
                    __func__, ctx->nnew);
                if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
                    (r = sshpkt_put_cstring(ssh,
                    "hostkeys-prove-00@openssh.com")) != 0 ||
                    (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */
                        fatal("%s: cannot prepare packet: %s",
                            __func__, ssh_err(r));
                if ((buf = sshbuf_new()) == NULL)
                        fatal("%s: sshbuf_new", __func__);
                for (i = 0; i < ctx->nkeys; i++) {
                        if (ctx->keys_seen[i])
                                continue;
                        sshbuf_reset(buf);
                        if ((r = sshkey_putb(ctx->keys[i], buf)) != 0)
                                fatal("%s: sshkey_putb: %s",
                                    __func__, ssh_err(r));
                        if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
                                fatal("%s: sshpkt_put_string: %s",
                                    __func__, ssh_err(r));
                }
                if ((r = sshpkt_send(ssh)) != 0)
                        fatal("%s: sshpkt_send: %s", __func__, ssh_err(r));
                client_register_global_confirm(
                    client_global_hostkeys_private_confirm, ctx);
                ctx = NULL;  /* will be freed in callback */
        }

        /* Success */
 out:
        hostkeys_update_ctx_free(ctx);
        sshkey_free(key);
        sshbuf_free(buf);
        /*
         * NB. Return success for all cases. The server doesn't need to know
         * what the client does with its hosts file.
         */
        return 1;
}

static int
client_input_global_request(int type, u_int32_t seq, void *ctxt)
{
        char *rtype;
        int want_reply;
        int success = 0;

        rtype = packet_get_cstring(NULL);
        want_reply = packet_get_char();
        debug("client_input_global_request: rtype %s want_reply %d",
            rtype, want_reply);
        if (strcmp(rtype, "hostkeys-00@openssh.com") == 0)
                success = client_input_hostkeys();
        if (want_reply) {
                packet_start(success ?
                    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
                packet_send();
                packet_write_wait();
        }
        free(rtype);
        return 0;
}

void
client_session2_setup(int id, int want_tty, int want_subsystem,
    const char *term, struct termios *tiop, int in_fd, Buffer *cmd, char **env)
{
        int len;
        Channel *c = NULL;

        debug2("%s: id %d", __func__, id);

        if ((c = channel_lookup(id)) == NULL)
                fatal("client_session2_setup: channel %d: unknown channel", id);

        packet_set_interactive(want_tty,
            options.ip_qos_interactive, options.ip_qos_bulk);

        if (want_tty) {
                struct winsize ws;

                /* Store window size in the packet. */
                if (ioctl(in_fd, TIOCGWINSZ, &ws) < 0)
                        memset(&ws, 0, sizeof(ws));

                channel_request_start(id, "pty-req", 1);
                client_expect_confirm(id, "PTY allocation", CONFIRM_TTY);
                packet_put_cstring(term != NULL ? term : "");
                packet_put_int((u_int)ws.ws_col);
                packet_put_int((u_int)ws.ws_row);
                packet_put_int((u_int)ws.ws_xpixel);
                packet_put_int((u_int)ws.ws_ypixel);
                if (tiop == NULL)
                        tiop = get_saved_tio();
                tty_make_modes(-1, tiop);
                packet_send();
                /* XXX wait for reply */
                c->client_tty = 1;
        }

        /* Transfer any environment variables from client to server */
        if (options.num_send_env != 0 && env != NULL) {
                int i, j, matched;
                char *name, *val;

                debug("Sending environment.");
                for (i = 0; env[i] != NULL; i++) {
                        /* Split */
                        name = xstrdup(env[i]);
                        if ((val = strchr(name, '=')) == NULL) {
                                free(name);
                                continue;
                        }
                        *val++ = '\0';

                        matched = 0;
                        for (j = 0; j < options.num_send_env; j++) {
                                if (match_pattern(name, options.send_env[j])) {
                                        matched = 1;
                                        break;
                                }
                        }
                        if (!matched) {
                                debug3("Ignored env %s", name);
                                free(name);
                                continue;
                        }

                        debug("Sending env %s = %s", name, val);
                        channel_request_start(id, "env", 0);
                        packet_put_cstring(name);
                        packet_put_cstring(val);
                        packet_send();
                        free(name);
                }
        }

        len = buffer_len(cmd);
        if (len > 0) {
                if (len > 900)
                        len = 900;
                if (want_subsystem) {
                        debug("Sending subsystem: %.*s",
                            len, (u_char*)buffer_ptr(cmd));
                        channel_request_start(id, "subsystem", 1);
                        client_expect_confirm(id, "subsystem", CONFIRM_CLOSE);
                } else {
                        debug("Sending command: %.*s",
                            len, (u_char*)buffer_ptr(cmd));
                        channel_request_start(id, "exec", 1);
                        client_expect_confirm(id, "exec", CONFIRM_CLOSE);
                }
                packet_put_string(buffer_ptr(cmd), buffer_len(cmd));
                packet_send();
        } else {
                channel_request_start(id, "shell", 1);
                client_expect_confirm(id, "shell", CONFIRM_CLOSE);
                packet_send();
        }
}

static void
client_init_dispatch_20(void)
{
        dispatch_init(&dispatch_protocol_error);

        dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
        dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
        dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
        dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
        dispatch_set(SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
        dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
        dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
        dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
        dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
        dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
        dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
        dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);

        /* rekeying */
        dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);

        /* global request reply messages */
        dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
        dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
}

static void
client_init_dispatch_13(void)
{
        dispatch_init(NULL);
        dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
        dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
        dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
        dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
        dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
        dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
        dispatch_set(SSH_SMSG_EXITSTATUS, &client_input_exit_status);
        dispatch_set(SSH_SMSG_STDERR_DATA, &client_input_stderr_data);
        dispatch_set(SSH_SMSG_STDOUT_DATA, &client_input_stdout_data);

        dispatch_set(SSH_SMSG_AGENT_OPEN, options.forward_agent ?
            &client_input_agent_open : &deny_input_open);
        dispatch_set(SSH_SMSG_X11_OPEN, options.forward_x11 ?
            &x11_input_open : &deny_input_open);
}

static void
client_init_dispatch_15(void)
{
        client_init_dispatch_13();
        dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
        dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, & channel_input_oclose);
}

static void
client_init_dispatch(void)
{
        if (compat20)
                client_init_dispatch_20();
        else if (compat13)
                client_init_dispatch_13();
        else
                client_init_dispatch_15();
}

void
client_stop_mux(void)
{
        if (options.control_path != NULL && muxserver_sock != -1)
                unlink(options.control_path);
        /*
         * If we are in persist mode, or don't have a shell, signal that we
         * should close when all active channels are closed.
         */
        if (options.control_persist || no_shell_flag) {
                session_closed = 1;
                setproctitle("[stopped mux]");
        }
}

/* client specific fatal cleanup */
void
cleanup_exit(int i)
{
        leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
        leave_non_blocking();
        if (options.control_path != NULL && muxserver_sock != -1)
                unlink(options.control_path);
        ssh_kill_proxy_command();
        _exit(i);
}