nrelease - fix/improve livecd

[dragonfly.git] / crypto / openssh / clientloop.c

/* $OpenBSD: clientloop.c,v 1.380 2022/06/03 04:30:46 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/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
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.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 "ssh2.h"
#include "packet.h"
#include "sshbuf.h"
#include "compat.h"
#include "channels.h"
#include "dispatch.h"
#include "sshkey.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"

/* Permitted RSA signature algorithms for UpdateHostkeys proofs */
#define HOSTKEY_PROOF_RSA_ALGS  "rsa-sha2-512,rsa-sha2-256"

/* import options */
extern Options options;

/* 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;

/*
 * If this field is not NULL, the ForwardAgent socket is this path and different
 * instead of SSH_AUTH_SOCK.
 */
extern char *forward_agent_sock_path;

/*
 * 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;

/* 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 last_was_cr;         /* Last character was a newline. */
static int exit_status;         /* Used to store the command exit status. */
static struct sshbuf *stderr_buffer;    /* Used for final exit message. */
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 time_t server_alive_time;        /* Time to do server_alive_check */

static void client_init_dispatch(struct ssh *ssh);
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 */
/* XXX move to struct ssh? */
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, struct sshbuf *);
static void quit_message(const char *fmt, ...)
    __attribute__((__format__ (printf, 1, 2)));

static void
quit_message(const char *fmt, ...)
{
        char *msg;
        va_list args;
        int r;

        va_start(args, fmt);
        xvasprintf(&msg, fmt, args);
        va_end(args);

        if ((r = sshbuf_putf(stderr_buffer, "%s\r\n", msg)) != 0)
                fatal_fr(r, "sshbuf_putf");
        quit_pending = 1;
}

/*
 * 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 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;
}

/*
 * 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(struct ssh *ssh)
{
        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(ssh)) {
                /* some client connections are still open */
                if (control_persist_exit_time > 0)
                        debug2_f("cancel scheduled exit");
                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_f("schedule exit in %d seconds",
                    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(struct ssh *ssh, const char *display,
    const char *xauth_path, u_int trusted, u_int timeout,
    char **_proto, char **_data)
{
        char *cmd, 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, 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_f("display name too long");
                                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_f("mkdtemp: %s", strerror(errno));
                                return -1;
                        }
                        do_unlink = 1;
                        if ((r = snprintf(xauthfile, sizeof(xauthfile),
                            "%s/xauthfile", xauthdir)) < 0 ||
                            (size_t)r >= sizeof(xauthfile)) {
                                error_f("xauthfile path too long");
                                rmdir(xauthdir);
                                return -1;
                        }

                        if (timeout == 0) {
                                /* auth doesn't time out */
                                xasprintf(&cmd, "%s -f %s generate %s %s "
                                    "untrusted 2>%s",
                                    xauth_path, xauthfile, display,
                                    SSH_X11_PROTO, _PATH_DEVNULL);
                        } else {
                                /* Add some slack to requested expiry */
                                if (timeout < UINT_MAX - X11_TIMEOUT_SLACK)
                                        x11_timeout_real = timeout +
                                            X11_TIMEOUT_SLACK;
                                else {
                                        /* Don't overflow on long timeouts */
                                        x11_timeout_real = UINT_MAX;
                                }
                                xasprintf(&cmd, "%s -f %s generate %s %s "
                                    "untrusted timeout %u 2>%s",
                                    xauth_path, xauthfile, display,
                                    SSH_X11_PROTO, x11_timeout_real,
                                    _PATH_DEVNULL);
                        }
                        debug2_f("xauth command: %s", cmd);

                        if (timeout != 0 && 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(ssh,
                                    x11_refuse_time);
                        }
                        if (system(cmd) == 0)
                                generated = 1;
                        free(cmd);
                }

                /*
                 * 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) {
                        xasprintf(&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);
                        free(cmd);
                }
        }

        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_int8_t rnd[16];
                u_int i;

                logit("Warning: No xauth data; "
                    "using fake authentication data for X11 forwarding.");
                strlcpy(proto, SSH_X11_PROTO, sizeof proto);
                arc4random_buf(rnd, sizeof(rnd));
                for (i = 0; i < sizeof(rnd); i++) {
                        snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
                            rnd[i]);
                }
        }

        return 0;
}

/*
 * 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(struct ssh *ssh)
{
        if (!received_window_change_signal)
                return;
        received_window_change_signal = 0;
        debug2_f("changed");
        channel_send_window_changes(ssh);
}

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

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

        ssh_packet_set_alive_timeouts(ssh, 0);
        return 0;
}

static void
schedule_server_alive_check(void)
{
        if (options.server_alive_interval > 0)
                server_alive_time = monotime() + options.server_alive_interval;
}

static void
server_alive_check(struct ssh *ssh)
{
        int r;

        if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) {
                logit("Timeout, server %s not responding.", host);
                cleanup_exit(255);
        }
        if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
            (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 ||
            (r = sshpkt_put_u8(ssh, 1)) != 0 ||         /* boolean: want reply */
            (r = sshpkt_send(ssh)) != 0)
                fatal_fr(r, "send packet");
        /* Insert an empty placeholder to maintain ordering */
        client_register_global_confirm(NULL, NULL);
        schedule_server_alive_check();
}

/*
 * 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(struct ssh *ssh, struct pollfd **pfdp,
    u_int *npfd_allocp, u_int *npfd_activep, int rekeying,
    int *conn_in_readyp, int *conn_out_readyp)
{
        int timeout_secs, pollwait;
        time_t minwait_secs = 0, now = monotime();
        int ret;
        u_int p;

        *conn_in_readyp = *conn_out_readyp = 0;

        /* Prepare channel poll. First two pollfd entries are reserved */
        channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2,
            &minwait_secs);
        if (*npfd_activep < 2)
                fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */

        /* channel_prepare_poll could have closed the last channel */
        if (session_closed && !channel_still_open(ssh) &&
            !ssh_packet_have_data_to_write(ssh)) {
                /* clear events since we did not call poll() */
                for (p = 0; p < *npfd_activep; p++)
                        (*pfdp)[p].revents = 0;
                return;
        }

        /* Monitor server connection on reserved pollfd entries */
        (*pfdp)[0].fd = connection_in;
        (*pfdp)[0].events = POLLIN;
        (*pfdp)[1].fd = connection_out;
        (*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0;

        /*
         * Wait for something to happen.  This will suspend the process until
         * some polled 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)
                timeout_secs = MAXIMUM(server_alive_time - now, 0);
        if (options.rekey_interval > 0 && !rekeying)
                timeout_secs = MINIMUM(timeout_secs,
                    ssh_packet_get_rekey_timeout(ssh));
        set_control_persist_exit_time(ssh);
        if (control_persist_exit_time > 0) {
                timeout_secs = MINIMUM(timeout_secs,
                        control_persist_exit_time - now);
                if (timeout_secs < 0)
                        timeout_secs = 0;
        }
        if (minwait_secs != 0)
                timeout_secs = MINIMUM(timeout_secs, (int)minwait_secs);
        if (timeout_secs == INT_MAX)
                pollwait = -1;
        else if (timeout_secs >= INT_MAX / 1000)
                pollwait = INT_MAX;
        else
                pollwait = timeout_secs * 1000;

        ret = poll(*pfdp, *npfd_activep, pollwait);

        if (ret == -1) {
                /*
                 * We have to clear the events because we return.
                 * We have to return, because the mainloop checks for the flags
                 * set by the signal handlers.
                 */
                for (p = 0; p < *npfd_activep; p++)
                        (*pfdp)[p].revents = 0;
                if (errno == EINTR)
                        return;
                /* Note: we might still have data in the buffers. */
                quit_message("poll: %s", strerror(errno));
                return;
        }

        *conn_in_readyp = (*pfdp)[0].revents != 0;
        *conn_out_readyp = (*pfdp)[1].revents != 0;

        if (options.server_alive_interval > 0 && !*conn_in_readyp &&
            monotime() >= server_alive_time) {
                /*
                 * ServerAlive check is needed. We can't rely on the poll
                 * timing out since traffic on the client side such as port
                 * forwards can keep waking it up.
                 */
                server_alive_check(ssh);
        }
}

static void
client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr)
{
        /* Flush stdout and stderr buffers. */
        if (sshbuf_len(bout) > 0)
                atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout),
                    sshbuf_len(bout));
        if (sshbuf_len(berr) > 0)
                atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr),
                    sshbuf_len(berr));

        leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);

        sshbuf_reset(bin);
        sshbuf_reset(bout);
        sshbuf_reset(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;

        enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
}

static void
client_process_net_input(struct ssh *ssh)
{
        int r;

        /*
         * Read input from the server, and add any such data to the buffer of
         * the packet subsystem.
         */
        schedule_server_alive_check();
        if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
                return; /* success */
        if (r == SSH_ERR_SYSTEM_ERROR) {
                if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
                        return;
                if (errno == EPIPE) {
                        quit_message("Connection to %s closed by remote host.",
                            host);
                        return;
                }
        }
        quit_message("Read from remote host %s: %s", host, ssh_err(r));
}

static void
client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx)
{
        struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
        char errmsg[256];
        int r, 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 suppress 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) {
                        debug3_f("channel %d: mux request: %s", c->self,
                            cr->request_type);
                        if ((r = sshbuf_put(c->extended, errmsg,
                            strlen(errmsg))) != 0)
                                fatal_fr(r, "sshbuf_put");
                } 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(ssh, c);
                } else if (cr->action == CONFIRM_CLOSE) {
                        chan_read_failed(ssh, c);
                        chan_write_failed(ssh, c);
                }
        }
        free(cr);
}

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

void
client_expect_confirm(struct ssh *ssh, 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(ssh, 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_f("last_gc->ref_count = %d",
                            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(struct ssh *ssh)
{
        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 = ssh_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;
        }

        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(ssh, &fwd) == 0;
                else if (dynamic)
                        ok = channel_cancel_lport_listener(ssh, &fwd,
                            0, &options.fwd_opts) > 0;
                else
                        ok = channel_cancel_lport_listener(ssh, &fwd,
                            CHANNEL_CANCEL_PORT_STATIC,
                            &options.fwd_opts) > 0;
                if (!ok) {
                        logit("Unknown 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(ssh, &fwd,
                            &options.fwd_opts)) {
                                logit("Port forwarding failed.");
                                goto out;
                        }
                } else {
                        if (channel_request_remote_forwarding(ssh, &fwd) < 0) {
                                logit("Port forwarding failed.");
                                goto out;
                        }
                }
                logit("Forwarding port.");
        }

out:
        ssh_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_MUXCLIENT      1       /* don't show in mux client sessions */
#define SUPPRESS_MUXMASTER      2       /* don't show in mux master sessions */
#define SUPPRESS_SYSLOG         4       /* 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_NEVER},
    {"C",  "open a command line", SUPPRESS_MUXCLIENT},
    {"R",  "request rekey", SUPPRESS_NEVER},
    {"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(struct sshbuf *b, int escape_char, int mux_client,
    int using_stderr)
{
        unsigned int i, suppress_flags;
        int r;

        if ((r = sshbuf_putf(b,
            "%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0)
                fatal_fr(r, "sshbuf_putf");

        suppress_flags =
            (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;
                if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n",
                    escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0)
                        fatal_fr(r, "sshbuf_putf");
        }

        if ((r = sshbuf_putf(b,
            " %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)) != 0)
                fatal_fr(r, "sshbuf_putf");
}

/*
 * Process the characters one by one.
 */
static int
process_escapes(struct ssh *ssh, Channel *c,
    struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr,
    char *buf, int len)
{
        pid_t pid;
        int r, bytes = 0;
        u_int i;
        u_char ch;
        char *s;
        struct escape_filter_ctx *efc = c->filter_ctx == NULL ?
            NULL : (struct escape_filter_ctx *)c->filter_ctx;

        if (c->filter_ctx == NULL)
                return 0;

        if (len <= 0)
                return (0);

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

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

                        /* Process the escaped character. */
                        switch (ch) {
                        case '.':
                                /* Terminate the connection. */
                                if ((r = sshbuf_putf(berr, "%c.\r\n",
                                    efc->escape_char)) != 0)
                                        fatal_fr(r, "sshbuf_putf");
                                if (c && c->ctl_chan != -1) {
                                        chan_read_failed(ssh, c);
                                        chan_write_failed(ssh, c);
                                        if (c->detach_user) {
                                                c->detach_user(ssh,
                                                    c->self, NULL);
                                        }
                                        c->type = SSH_CHANNEL_ABANDONED;
                                        sshbuf_reset(c->input);
                                        chan_ibuf_empty(ssh, 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);
                                        if ((r = sshbuf_putf(berr,
                                            "%c%s escape not available to "
                                            "multiplexed sessions\r\n",
                                            efc->escape_char, b)) != 0)
                                                fatal_fr(r, "sshbuf_putf");
                                        continue;
                                }
                                /* Suspend the program. Inform the user */
                                if ((r = sshbuf_putf(berr,
                                    "%c^Z [suspend ssh]\r\n",
                                    efc->escape_char)) != 0)
                                        fatal_fr(r, "sshbuf_putf");

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

                                /* We have been continued. */
                                continue;

                        case 'B':
                                if ((r = sshbuf_putf(berr,
                                    "%cB\r\n", efc->escape_char)) != 0)
                                        fatal_fr(r, "sshbuf_putf");
                                channel_request_start(ssh, c->self, "break", 0);
                                if ((r = sshpkt_put_u32(ssh, 1000)) != 0 ||
                                    (r = sshpkt_send(ssh)) != 0)
                                        fatal_fr(r, "send packet");
                                continue;

                        case 'R':
                                if (ssh->compat & 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()) {
                                        if ((r = sshbuf_putf(berr,
                                            "%c%c [Logging to syslog]\r\n",
                                            efc->escape_char, ch)) != 0)
                                                fatal_fr(r, "sshbuf_putf");
                                        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);
                                if ((r = sshbuf_putf(berr,
                                    "%c%c [LogLevel %s]\r\n",
                                    efc->escape_char, ch,
                                    log_level_name(options.log_level))) != 0)
                                        fatal_fr(r, "sshbuf_putf");
                                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(ssh);

                                if ((r = sshbuf_putf(berr, "%c& "
                                    "[backgrounded]\n", efc->escape_char)) != 0)
                                        fatal_fr(r, "sshbuf_putf");

                                /* Fork into background. */
                                pid = fork();
                                if (pid == -1) {
                                        error("fork: %.100s", strerror(errno));
                                        continue;
                                }
                                if (pid != 0) { /* This is the parent. */
                                        /* The parent just exits. */
                                        exit(0);
                                }
                                /* The child continues serving connections. */
                                /* fake EOF on stdin */
                                if ((r = sshbuf_put_u8(bin, 4)) != 0)
                                        fatal_fr(r, "sshbuf_put_u8");
                                return -1;
                        case '?':
                                print_escape_help(berr, efc->escape_char,
                                    (c && c->ctl_chan != -1),
                                    log_is_on_stderr());
                                continue;

                        case '#':
                                if ((r = sshbuf_putf(berr, "%c#\r\n",
                                    efc->escape_char)) != 0)
                                        fatal_fr(r, "sshbuf_putf");
                                s = channel_open_message(ssh);
                                if ((r = sshbuf_put(berr, s, strlen(s))) != 0)
                                        fatal_fr(r, "sshbuf_put");
                                free(s);
                                continue;

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

                        default:
                                if (ch != efc->escape_char) {
                                        if ((r = sshbuf_put_u8(bin,
                                            efc->escape_char)) != 0)
                                                fatal_fr(r, "sshbuf_put_u8");
                                        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 == efc->escape_char) {
                                /*
                                 * It is. Set the flag and continue to
                                 * next character.
                                 */
                                efc->escape_pending = 1;
                                continue;
                        }
                }

                /*
                 * Normal character.  Record whether it was a newline,
                 * and append it to the buffer.
                 */
                last_was_cr = (ch == '\r' || ch == '\n');
                if ((r = sshbuf_put_u8(bin, ch)) != 0)
                        fatal_fr(r, "sshbuf_put_u8");
                bytes++;
        }
        return bytes;
}

/*
 * 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(struct ssh *ssh)
{
        ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending);
}

/* 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(struct ssh *ssh, int cid, void *ctx)
{
        free(ctx);
}

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

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

static void
client_channel_closed(struct ssh *ssh, int id, void *arg)
{
        channel_cancel_cleanup(ssh, 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(struct ssh *ssh, int have_pty, int escape_char_arg,
    int ssh2_chan_id)
{
        struct pollfd *pfd = NULL;
        u_int npfd_alloc = 0, npfd_active = 0;
        double start_time, total_time;
        int r, len;
        u_int64_t ibytes, obytes;
        int conn_in_ready, conn_out_ready;

        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 sendfd proc exec id tty",
                    NULL) == -1)
                        fatal_f("pledge(): %s", 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_f("pledge(): %s", strerror(errno));

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

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

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

        start_time = monotime_double();

        /* Initialize variables. */
        last_was_cr = 1;
        exit_status = -1;
        connection_in = ssh_packet_get_connection_in(ssh);
        connection_out = ssh_packet_get_connection_out(ssh);

        quit_pending = 0;

        /* Initialize buffer. */
        if ((stderr_buffer = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        client_init_dispatch(ssh);

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

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

        session_ident = ssh2_chan_id;
        if (session_ident != -1) {
                if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
                        channel_register_filter(ssh, session_ident,
                            client_simple_escape_filter, NULL,
                            client_filter_cleanup,
                            client_new_escape_filter_ctx(
                            escape_char_arg));
                }
                channel_register_cleanup(ssh, session_ident,
                    client_channel_closed, 0);
        }

        schedule_server_alive_check();

        /* 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(ssh);

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

                if (ssh_packet_is_rekeying(ssh)) {
                        debug("rekeying in progress");
                } else if (need_rekeying) {
                        /* manual rekey request */
                        debug("need rekeying");
                        if ((r = kex_start_rekex(ssh)) != 0)
                                fatal_fr(r, "kex_start_rekex");
                        need_rekeying = 0;
                } else {
                        /*
                         * Make packets from buffered channel data, and
                         * enqueue them for sending to the server.
                         */
                        if (ssh_packet_not_very_much_data_to_write(ssh))
                                channel_output_poll(ssh);

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

                        if (quit_pending)
                                break;
                }
                /*
                 * Wait until we have something to do (something becomes
                 * available on one of the descriptors).
                 */
                client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc,
                    &npfd_active, ssh_packet_is_rekeying(ssh),
                    &conn_in_ready, &conn_out_ready);

                if (quit_pending)
                        break;

                /* Do channel operations. */
                channel_after_poll(ssh, pfd, npfd_active);

                /* Buffer input from the connection.  */
                if (conn_in_ready)
                        client_process_net_input(ssh);

                if (quit_pending)
                        break;

                /* A timeout may have triggered rekeying */
                if ((r = ssh_packet_check_rekey(ssh)) != 0)
                        fatal_fr(r, "cannot start rekeying");

                /*
                 * Send as much buffered packet data as possible to the
                 * sender.
                 */
                if (conn_out_ready) {
                        if ((r = ssh_packet_write_poll(ssh)) != 0) {
                                sshpkt_fatal(ssh, r,
                                    "%s: ssh_packet_write_poll", __func__);
                        }
                }

                /*
                 * 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(pfd);

        /* Terminate the session. */

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

        if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
            (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 ||
            (r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 ||
            (r = sshpkt_put_cstring(ssh, "")) != 0 ||   /* language tag */
            (r = sshpkt_send(ssh)) != 0 ||
            (r = ssh_packet_write_wait(ssh)) != 0)
                fatal_fr(r, "send disconnect");

        channel_free_all(ssh);

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

        /*
         * 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 (options.session_type == SESSION_TYPE_NONE &&
            received_signal == SIGTERM) {
                received_signal = 0;
                exit_status = 0;
        }

        if (received_signal) {
                verbose("Killed by signal %d.", (int) received_signal);
                cleanup_exit(255);
        }

        /*
         * In interactive mode (with pseudo tty) display a message indicating
         * that the connection has been closed.
         */
        if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO)
                quit_message("Connection to %s closed.", host);

        /* Output any buffered data for stderr. */
        if (sshbuf_len(stderr_buffer) > 0) {
                len = atomicio(vwrite, fileno(stderr),
                    (u_char *)sshbuf_ptr(stderr_buffer),
                    sshbuf_len(stderr_buffer));
                if (len < 0 || (u_int)len != sshbuf_len(stderr_buffer))
                        error("Write failed flushing stderr buffer.");
                else if ((r = sshbuf_consume(stderr_buffer, len)) != 0)
                        fatal_fr(r, "sshbuf_consume");
        }

        /* Clear and free any buffers. */
        sshbuf_free(stderr_buffer);

        /* Report bytes transferred, and transfer rates. */
        total_time = monotime_double() - start_time;
        ssh_packet_get_bytes(ssh, &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 Channel *
client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type,
    int rchan, u_int rwindow, u_int rmaxpack)
{
        Channel *c = NULL;
        struct sshbuf *b = NULL;
        char *listen_address, *originator_address;
        u_int listen_port, originator_port;
        int r;

        /* Get rest of the packet */
        if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 ||
            (r = sshpkt_get_u32(ssh, &listen_port)) != 0 ||
            (r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 ||
            (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
            (r = sshpkt_get_end(ssh)) != 0)
                fatal_fr(r, "parse packet");

        debug_f("listen %s port %d, originator %s port %d",
            listen_address, listen_port, originator_address, originator_port);

        if (listen_port > 0xffff)
                error_f("invalid listen port");
        else if (originator_port > 0xffff)
                error_f("invalid originator port");
        else {
                c = channel_connect_by_listen_address(ssh,
                    listen_address, listen_port, "forwarded-tcpip",
                    originator_address);
        }

        if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
                if ((b = sshbuf_new()) == NULL) {
                        error_f("alloc reply");
                        goto out;
                }
                /* reconstruct and send to muxclient */
                if ((r = sshbuf_put_u8(b, 0)) != 0 ||   /* padlen */
                    (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
                    (r = sshbuf_put_cstring(b, request_type)) != 0 ||
                    (r = sshbuf_put_u32(b, rchan)) != 0 ||
                    (r = sshbuf_put_u32(b, rwindow)) != 0 ||
                    (r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
                    (r = sshbuf_put_cstring(b, listen_address)) != 0 ||
                    (r = sshbuf_put_u32(b, listen_port)) != 0 ||
                    (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
                    (r = sshbuf_put_u32(b, originator_port)) != 0 ||
                    (r = sshbuf_put_stringb(c->output, b)) != 0) {
                        error_fr(r, "compose for muxclient");
                        goto out;
                }
        }

 out:
        sshbuf_free(b);
        free(originator_address);
        free(listen_address);
        return c;
}

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

        /* Get the remote path. */
        if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 ||
            (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 ||    /* reserved */
            (r = sshpkt_get_end(ssh)) != 0)
                fatal_fr(r, "parse packet");

        debug_f("request: %s", listen_path);

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

static Channel *
client_request_x11(struct ssh *ssh, const char *request_type, int rchan)
{
        Channel *c = NULL;
        char *originator;
        u_int originator_port;
        int r, 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;
        }
        if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
            (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
            (r = sshpkt_get_end(ssh)) != 0)
                fatal_fr(r, "parse packet");
        /* XXX check permission */
        /* XXX range check originator port? */
        debug("client_request_x11: request from %s %u", originator,
            originator_port);
        free(originator);
        sock = x11_connect_display(ssh);
        if (sock < 0)
                return NULL;
        c = channel_new(ssh, "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(struct ssh *ssh, 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 (forward_agent_sock_path == NULL) {
                r = ssh_get_authentication_socket(&sock);
        } else {
                r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock);
        }
        if (r != 0) {
                if (r != SSH_ERR_AGENT_NOT_PRESENT)
                        debug_fr(r, "ssh_get_authentication_socket");
                return NULL;
        }
        if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey,
            ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0)
                debug_f("bound agent to hostkey");
        else
                debug2_fr(r, "ssh_agent_bind_hostkey");

        c = channel_new(ssh, "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;
}

char *
client_request_tun_fwd(struct ssh *ssh, int tun_mode,
    int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx)
{
        Channel *c;
        int r, fd;
        char *ifname = NULL;

        if (tun_mode == SSH_TUNMODE_NO)
                return 0;

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

        /* Open local tunnel device */
        if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) {
                error("Tunnel device open failed.");
                return NULL;
        }
        debug("Tunnel forwarding using interface %s", ifname);

        c = channel_new(ssh, "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(ssh, c->self, sys_tun_infilter,
                    sys_tun_outfilter, NULL, NULL);
#endif

        if (cb != NULL)
                channel_register_open_confirm(ssh, c->self, cb, cbctx);

        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
            (r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 ||
            (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
            (r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 ||
            (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
            (r = sshpkt_put_u32(ssh, tun_mode)) != 0 ||
            (r = sshpkt_put_u32(ssh, remote_tun)) != 0 ||
            (r = sshpkt_send(ssh)) != 0)
                sshpkt_fatal(ssh, r, "%s: send reply", __func__);

        return ifname;
}

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

        if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 ||
            (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
            (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
            (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
                goto out;

        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(ssh, ctype, rchan, rwindow,
                    rmaxpack);
        } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
                c = client_request_forwarded_streamlocal(ssh, ctype, rchan);
        } else if (strcmp(ctype, "x11") == 0) {
                c = client_request_x11(ssh, ctype, rchan);
        } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
                c = client_request_agent(ssh, ctype, rchan);
        }
        if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
                debug3("proxied to downstream: %s", ctype);
        } else if (c != NULL) {
                debug("confirm %s", ctype);
                c->remote_id = rchan;
                c->have_remote_id = 1;
                c->remote_window = rwindow;
                c->remote_maxpacket = rmaxpack;
                if (c->type != SSH_CHANNEL_CONNECTING) {
                        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
                            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
                            (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
                            (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
                            (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
                            (r = sshpkt_send(ssh)) != 0)
                                sshpkt_fatal(ssh, r, "%s: send reply", __func__);
                }
        } else {
                debug("failure %s", ctype);
                if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
                    (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
                    (r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 ||
                    (r = sshpkt_put_cstring(ssh, "open failed")) != 0 ||
                    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
                    (r = sshpkt_send(ssh)) != 0)
                        sshpkt_fatal(ssh, r, "%s: send failure", __func__);
        }
        r = 0;
 out:
        free(ctype);
        return r;
}

static int
client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
{
        Channel *c = NULL;
        char *rtype = NULL;
        u_char reply;
        u_int id, exitval;
        int r, success = 0;

        if ((r = sshpkt_get_u32(ssh, &id)) != 0)
                return r;
        if (id <= INT_MAX)
                c = channel_lookup(ssh, id);
        if (channel_proxy_upstream(c, type, seq, ssh))
                return 0;
        if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
            (r = sshpkt_get_u8(ssh, &reply)) != 0)
                goto out;

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

        if (c == NULL) {
                error("client_input_channel_req: channel %d: "
                    "unknown channel", id);
        } else if (strcmp(rtype, "eow@openssh.com") == 0) {
                if ((r = sshpkt_get_end(ssh)) != 0)
                        goto out;
                chan_rcvd_eow(ssh, c);
        } else if (strcmp(rtype, "exit-status") == 0) {
                if ((r = sshpkt_get_u32(ssh, &exitval)) != 0)
                        goto out;
                if (c->ctl_chan != -1) {
                        mux_exit_message(ssh, c, exitval);
                        success = 1;
                } else if ((int)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_f("no sink for exit-status on channel %d",
                            id);
                }
                if ((r = sshpkt_get_end(ssh)) != 0)
                        goto out;
        }
        if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
                if (!c->have_remote_id)
                        fatal_f("channel %d: no remote_id", c->self);
                if ((r = sshpkt_start(ssh, success ?
                    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
                    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
                    (r = sshpkt_send(ssh)) != 0)
                        sshpkt_fatal(ssh, r, "%s: send failure", __func__);
        }
        r = 0;
 out:
        free(rtype);
        return r;
}

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_match is filled in by hostkeys_find() and later (for new
         * keys) by client_global_hostkeys_private_confirm().
         */
        struct sshkey **keys;
        u_int *keys_match;      /* mask of HKF_MATCH_* from hostfile.h */
        int *keys_verified;     /* flag for new keys verified by server */
        size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */

        /*
         * 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;

        /* Various special cases. */
        int complex_hostspec;   /* wildcard or manual pattern-list host name */
        int ca_available;       /* saw CA key for this host */
        int old_key_seen;       /* saw old key with other name/addr */
        int other_name_seen;    /* saw key with other name/addr */
};

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_match);
        free(ctx->keys_verified);
        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);
}

/*
 * Returns non-zero if a known_hosts hostname list is not of a form that
 * can be handled by UpdateHostkeys. These include wildcard hostnames and
 * hostnames lists that do not follow the form host[,ip].
 */
static int
hostspec_is_complex(const char *hosts)
{
        char *cp;

        /* wildcard */
        if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL)
                return 1;
        /* single host/ip = ok */
        if ((cp = strchr(hosts, ',')) == NULL)
                return 0;
        /* more than two entries on the line */
        if (strchr(cp + 1, ',') != NULL)
                return 1;
        /* XXX maybe parse cp+1 and ensure it is an IP? */
        return 0;
}

/* callback to search for ctx->keys in known_hosts */
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->key == NULL)
                return 0;
        if (l->status != HKF_STATUS_MATCHED) {
                /* Record if one of the keys appears on a non-matching line */
                for (i = 0; i < ctx->nkeys; i++) {
                        if (sshkey_equal(l->key, ctx->keys[i])) {
                                ctx->other_name_seen = 1;
                                debug3_f("found %s key under different "
                                    "name/addr at %s:%ld",
                                    sshkey_ssh_name(ctx->keys[i]),
                                    l->path, l->linenum);
                                return 0;
                        }
                }
                return 0;
        }
        /* Don't proceed if revocation or CA markers are present */
        /* XXX relax this */
        if (l->marker != MRK_NONE) {
                debug3_f("hostkeys file %s:%ld has CA/revocation marker",
                    l->path, l->linenum);
                ctx->complex_hostspec = 1;
                return 0;
        }

        /* If CheckHostIP is enabled, then check for mismatched hostname/addr */
        if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) {
                if ((l->match & HKF_MATCH_HOST) == 0) {
                        /* Record if address matched a different hostname. */
                        ctx->other_name_seen = 1;
                        debug3_f("found address %s against different hostname "
                            "at %s:%ld", ctx->ip_str, l->path, l->linenum);
                        return 0;
                } else if ((l->match & HKF_MATCH_IP) == 0) {
                        /* Record if hostname matched a different address. */
                        ctx->other_name_seen = 1;
                        debug3_f("found hostname %s against different address "
                            "at %s:%ld", ctx->host_str, l->path, l->linenum);
                }
        }

        /*
         * UpdateHostkeys is skipped for wildcard host names and hostnames
         * that contain more than two entries (ssh never writes these).
         */
        if (hostspec_is_complex(l->hosts)) {
                debug3_f("hostkeys file %s:%ld complex host specification",
                    l->path, l->linenum);
                ctx->complex_hostspec = 1;
                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]))
                        continue;
                debug3_f("found %s key at %s:%ld",
                    sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
                ctx->keys_match[i] |= l->match;
                return 0;
        }
        /* This line contained a key that not offered by the server */
        debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key),
            l->path, l->linenum);
        if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1,
            sizeof(*ctx->old_keys))) == NULL)
                fatal_f("recallocarray failed nold = %zu", ctx->nold);
        ctx->old_keys = tmp;
        ctx->old_keys[ctx->nold++] = l->key;
        l->key = NULL;

        return 0;
}

/* callback to search for ctx->old_keys in known_hosts under other names */
static int
hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx)
{
        struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
        size_t i;
        int hashed;

        /* only care about lines that *don't* match the active host spec */
        if (l->status == HKF_STATUS_MATCHED || l->key == NULL)
                return 0;

        hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED);
        for (i = 0; i < ctx->nold; i++) {
                if (!sshkey_equal(l->key, ctx->old_keys[i]))
                        continue;
                debug3_f("found deprecated %s key at %s:%ld as %s",
                    sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum,
                    hashed ? "[HASHED]" : l->hosts);
                ctx->old_key_seen = 1;
                break;
        }
        return 0;
}

/*
 * Check known_hosts files for deprecated keys under other names. Returns 0
 * on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys
 * exist under names other than the active hostname/IP.
 */
static int
check_old_keys_othernames(struct hostkeys_update_ctx *ctx)
{
        size_t i;
        int r;

        debug2_f("checking for %zu deprecated keys", ctx->nold);
        for (i = 0; i < options.num_user_hostfiles; i++) {
                debug3_f("searching %s for %s / %s",
                    options.user_hostfiles[i], ctx->host_str,
                    ctx->ip_str ? ctx->ip_str : "(none)");
                if ((r = hostkeys_foreach(options.user_hostfiles[i],
                    hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str,
                    HKF_WANT_PARSE_KEY, 0)) != 0) {
                        if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
                                debug_f("hostkeys file %s does not exist",
                                    options.user_hostfiles[i]);
                                continue;
                        }
                        error_fr(r, "hostkeys_foreach failed for %s",
                            options.user_hostfiles[i]);
                        return -1;
                }
        }
        return 0;
}

static void
hostkey_change_preamble(LogLevel loglevel)
{
        do_log2(loglevel, "The server has updated its host keys.");
        do_log2(loglevel, "These changes were verified by the server's "
            "existing trusted key.");
}

static void
update_known_hosts(struct hostkeys_update_ctx *ctx)
{
        int r, was_raw = 0, first = 1;
        int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK;
        LogLevel loglevel = asking ?  SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
        char *fp, *response;
        size_t i;
        struct stat sb;

        for (i = 0; i < ctx->nkeys; i++) {
                if (!ctx->keys_verified[i])
                        continue;
                if ((fp = sshkey_fingerprint(ctx->keys[i],
                    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
                        fatal_f("sshkey_fingerprint failed");
                if (first && asking)
                        hostkey_change_preamble(loglevel);
                do_log2(loglevel, "Learned new hostkey: %s %s",
                    sshkey_type(ctx->keys[i]), fp);
                first = 0;
                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_f("sshkey_fingerprint failed");
                if (first && asking)
                        hostkey_change_preamble(loglevel);
                do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
                    sshkey_type(ctx->old_keys[i]), fp);
                first = 0;
                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);
        }
        if (options.update_hostkeys == 0)
                return;
        /*
         * 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).
         */
        for (i = 0; i < options.num_user_hostfiles; i++) {
                /*
                 * NB. keys are only added to hostfiles[0], for the rest we
                 * just delete the hostname entries.
                 */
                if (stat(options.user_hostfiles[i], &sb) != 0) {
                        if (errno == ENOENT) {
                                debug_f("known hosts file %s does not "
                                    "exist", options.user_hostfiles[i]);
                        } else {
                                error_f("known hosts file %s "
                                    "inaccessible: %s",
                                    options.user_hostfiles[i], strerror(errno));
                        }
                        continue;
                }
                if ((r = hostfile_replace_entries(options.user_hostfiles[i],
                    ctx->host_str, ctx->ip_str,
                    i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0,
                    options.hash_known_hosts, 0,
                    options.fingerprint_hash)) != 0) {
                        error_fr(r, "hostfile_replace_entries failed for %s",
                            options.user_hostfiles[i]);
                }
        }
}

static void
client_global_hostkeys_private_confirm(struct ssh *ssh, int type,
    u_int32_t seq, void *_ctx)
{
        struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
        size_t i, ndone;
        struct sshbuf *signdata;
        int r, plaintype;
        const u_char *sig;
        const char *rsa_kexalg = NULL;
        char *alg = NULL;
        size_t siglen;

        if (ctx->nnew == 0)
                fatal_f("ctx->nnew == 0"); /* sanity */
        if (type != SSH2_MSG_REQUEST_SUCCESS) {
                error("Server failed to confirm ownership of "
                    "private host keys");
                hostkeys_update_ctx_free(ctx);
                return;
        }
        if (sshkey_type_plain(sshkey_type_from_name(
            ssh->kex->hostkey_alg)) == KEY_RSA)
                rsa_kexalg = ssh->kex->hostkey_alg;
        if ((signdata = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        /*
         * 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_match[i] == 0.
         */
        for (ndone = i = 0; i < ctx->nkeys; i++) {
                if (ctx->keys_match[i])
                        continue;
                plaintype = sshkey_type_plain(ctx->keys[i]->type);
                /* 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_stringb(signdata,
                    ssh->kex->session_id)) != 0 ||
                    (r = sshkey_puts(ctx->keys[i], signdata)) != 0)
                        fatal_fr(r, "compose signdata");
                /* Extract and verify signature */
                if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
                        error_fr(r, "parse sig");
                        goto out;
                }
                if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) {
                        error_fr(r, "server gave unintelligible signature "
                            "for %s key %zu", sshkey_type(ctx->keys[i]), i);
                        goto out;
                }
                /*
                 * Special case for RSA keys: if a RSA hostkey was negotiated,
                 * then use its signature type for verification of RSA hostkey
                 * proofs. Otherwise, accept only RSA-SHA256/512 signatures.
                 */
                if (plaintype == KEY_RSA && rsa_kexalg == NULL &&
                    match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) {
                        debug_f("server used untrusted RSA signature algorithm "
                            "%s for key %zu, disregarding", alg, i);
                        free(alg);
                        /* zap the key from the list */
                        sshkey_free(ctx->keys[i]);
                        ctx->keys[i] = NULL;
                        ndone++;
                        continue;
                }
                debug3_f("verify %s key %zu using sigalg %s",
                    sshkey_type(ctx->keys[i]), i, alg);
                free(alg);
                if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
                    sshbuf_ptr(signdata), sshbuf_len(signdata),
                    plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) {
                        error_fr(r, "server gave bad signature for %s key %zu",
                            sshkey_type(ctx->keys[i]), i);
                        goto out;
                }
                /* Key is good. Mark it as 'seen' */
                ctx->keys_verified[i] = 1;
                ndone++;
        }
        /* Shouldn't happen */
        if (ndone != ctx->nnew)
                fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew);
        if ((r = sshpkt_get_end(ssh)) != 0) {
                error_f("protocol error");
                goto out;
        }

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

/*
 * Returns non-zero if the key is accepted by HostkeyAlgorithms.
 * Made slightly less trivial by the multiple RSA signature algorithm names.
 */
static int
key_accepted_by_hostkeyalgs(const struct sshkey *key)
{
        const char *ktype = sshkey_ssh_name(key);
        const char *hostkeyalgs = options.hostkeyalgorithms;

        if (key == NULL || key->type == KEY_UNSPEC)
                return 0;
        if (key->type == KEY_RSA &&
            (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 ||
            match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1))
                return 1;
        return match_pattern_list(ktype, hostkeyalgs, 0) == 1;
}

/*
 * 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(struct ssh *ssh)
{
        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;
        u_int want;

        if (hostkeys_seen)
                fatal_f("server already sent hostkeys");
        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_fr(r, "parse key");
                        goto out;
                }
                if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
                        do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ?
                            SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR,
                            "convert key");
                        continue;
                }
                fp = sshkey_fingerprint(key, options.fingerprint_hash,
                    SSH_FP_DEFAULT);
                debug3_f("received %s key %s", sshkey_type(key), fp);
                free(fp);

                if (!key_accepted_by_hostkeyalgs(key)) {
                        debug3_f("%s key not permitted by "
                            "HostkeyAlgorithms", sshkey_ssh_name(key));
                        continue;
                }
                /* Skip certs */
                if (sshkey_is_cert(key)) {
                        debug3_f("%s key is a certificate; skipping",
                            sshkey_ssh_name(key));
                        continue;
                }
                /* Ensure keys are unique */
                for (i = 0; i < ctx->nkeys; i++) {
                        if (sshkey_equal(key, ctx->keys[i])) {
                                error_f("received duplicated %s host key",
                                    sshkey_ssh_name(key));
                                goto out;
                        }
                }
                /* Key is good, record it */
                if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1,
                    sizeof(*ctx->keys))) == NULL)
                        fatal_f("recallocarray failed nkeys = %zu",
                            ctx->nkeys);
                ctx->keys = tmp;
                ctx->keys[ctx->nkeys++] = key;
                key = NULL;
        }

        if (ctx->nkeys == 0) {
                debug_f("server sent no hostkeys");
                goto out;
        }

        if ((ctx->keys_match = calloc(ctx->nkeys,
            sizeof(*ctx->keys_match))) == NULL ||
            (ctx->keys_verified = calloc(ctx->nkeys,
            sizeof(*ctx->keys_verified))) == NULL)
                fatal_f("calloc failed");

        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. */
        for (i = 0; i < options.num_user_hostfiles; i++) {
                debug_f("searching %s for %s / %s",
                    options.user_hostfiles[i], ctx->host_str,
                    ctx->ip_str ? ctx->ip_str : "(none)");
                if ((r = hostkeys_foreach(options.user_hostfiles[i],
                    hostkeys_find, ctx, ctx->host_str, ctx->ip_str,
                    HKF_WANT_PARSE_KEY, 0)) != 0) {
                        if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
                                debug_f("hostkeys file %s does not exist",
                                    options.user_hostfiles[i]);
                                continue;
                        }
                        error_fr(r, "hostkeys_foreach failed for %s",
                            options.user_hostfiles[i]);
                        goto out;
                }
        }

        /* Figure out if we have any new keys to add */
        ctx->nnew = ctx->nincomplete = 0;
        want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0);
        for (i = 0; i < ctx->nkeys; i++) {
                if (ctx->keys_match[i] == 0)
                        ctx->nnew++;
                if ((ctx->keys_match[i] & want) != want)
                        ctx->nincomplete++;
        }

        debug3_f("%zu server keys: %zu new, %zu retained, "
            "%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew,
            ctx->nkeys - ctx->nnew - ctx->nincomplete,
            ctx->nincomplete, ctx->nold);

        if (ctx->nnew == 0 && ctx->nold == 0) {
                debug_f("no new or deprecated keys from server");
                goto out;
        }

        /* Various reasons why we cannot proceed with the update */
        if (ctx->complex_hostspec) {
                debug_f("CA/revocation marker, manual host list or wildcard "
                    "host pattern found, skipping UserKnownHostsFile update");
                goto out;
        }
        if (ctx->other_name_seen) {
                debug_f("host key found matching a different name/address, "
                    "skipping UserKnownHostsFile update");
                goto out;
        }
        /*
         * If removing keys, check whether they appear under different
         * names/addresses and refuse to proceed if they do. This avoids
         * cases such as hosts with multiple names becoming inconsistent
         * with regards to CheckHostIP entries.
         * XXX UpdateHostkeys=force to override this (and other) checks?
         */
        if (ctx->nold != 0) {
                if (check_old_keys_othernames(ctx) != 0)
                        goto out; /* error already logged */
                if (ctx->old_key_seen) {
                        debug_f("key(s) for %s%s%s exist under other names; "
                            "skipping UserKnownHostsFile update",
                            ctx->host_str, ctx->ip_str == NULL ? "" : ",",
                            ctx->ip_str == NULL ? "" : ctx->ip_str);
                        goto out;
                }
        }

        if (ctx->nnew == 0) {
                /*
                 * We have some keys to remove or fix matching for.
                 * We can proceed to do this without requiring a fresh proof
                 * from the server.
                 */
                update_known_hosts(ctx);
                goto out;
        }
        /*
         * We have received previously-unseen keys from the server.
         * Ask the server to confirm ownership of the private halves.
         */
        debug3_f("asking server to prove ownership for %zu keys", 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_fr(r, "prepare hostkeys-prove");
        if ((buf = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new");
        for (i = 0; i < ctx->nkeys; i++) {
                if (ctx->keys_match[i])
                        continue;
                sshbuf_reset(buf);
                if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 ||
                    (r = sshpkt_put_stringb(ssh, buf)) != 0)
                        fatal_fr(r, "assemble hostkeys-prove");
        }
        if ((r = sshpkt_send(ssh)) != 0)
                fatal_fr(r, "send hostkeys-prove");
        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, struct ssh *ssh)
{
        char *rtype;
        u_char want_reply;
        int r, success = 0;

        if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
            (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
                goto out;
        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(ssh);
        if (want_reply) {
                if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS :
                    SSH2_MSG_REQUEST_FAILURE)) != 0 ||
                    (r = sshpkt_send(ssh)) != 0 ||
                    (r = ssh_packet_write_wait(ssh)) != 0)
                        goto out;
        }
        r = 0;
 out:
        free(rtype);
        return r;
}

static void
client_send_env(struct ssh *ssh, int id, const char *name, const char *val)
{
        int r;

        debug("channel %d: setting env %s = \"%s\"", id, name, val);
        channel_request_start(ssh, id, "env", 0);
        if ((r = sshpkt_put_cstring(ssh, name)) != 0 ||
            (r = sshpkt_put_cstring(ssh, val)) != 0 ||
            (r = sshpkt_send(ssh)) != 0)
                fatal_fr(r, "send setenv");
}

void
client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
    const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd,
    char **env)
{
        size_t i, j, len;
        int matched, r;
        char *name, *val;
        Channel *c = NULL;

        debug2_f("id %d", id);

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

        ssh_packet_set_interactive(ssh, 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) == -1)
                        memset(&ws, 0, sizeof(ws));

                channel_request_start(ssh, id, "pty-req", 1);
                client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
                if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : ""))
                    != 0 ||
                    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
                    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
                    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
                    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0)
                        fatal_fr(r, "build pty-req");
                if (tiop == NULL)
                        tiop = get_saved_tio();
                ssh_tty_make_modes(ssh, -1, tiop);
                if ((r = sshpkt_send(ssh)) != 0)
                        fatal_fr(r, "send pty-req");
                /* XXX wait for reply */
                c->client_tty = 1;
        }

        /* Transfer any environment variables from client to server */
        if (options.num_send_env != 0 && env != NULL) {
                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;
                        }
                        client_send_env(ssh, id, name, val);
                        free(name);
                }
        }
        for (i = 0; i < options.num_setenv; i++) {
                /* Split */
                name = xstrdup(options.setenv[i]);
                if ((val = strchr(name, '=')) == NULL) {
                        free(name);
                        continue;
                }
                *val++ = '\0';
                client_send_env(ssh, id, name, val);
                free(name);
        }

        len = sshbuf_len(cmd);
        if (len > 0) {
                if (len > 900)
                        len = 900;
                if (want_subsystem) {
                        debug("Sending subsystem: %.*s",
                            (int)len, (const u_char*)sshbuf_ptr(cmd));
                        channel_request_start(ssh, id, "subsystem", 1);
                        client_expect_confirm(ssh, id, "subsystem",
                            CONFIRM_CLOSE);
                } else {
                        debug("Sending command: %.*s",
                            (int)len, (const u_char*)sshbuf_ptr(cmd));
                        channel_request_start(ssh, id, "exec", 1);
                        client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
                }
                if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 ||
                    (r = sshpkt_send(ssh)) != 0)
                        fatal_fr(r, "send command");
        } else {
                channel_request_start(ssh, id, "shell", 1);
                client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
                if ((r = sshpkt_send(ssh)) != 0)
                        fatal_fr(r, "send shell");
        }
}

static void
client_init_dispatch(struct ssh *ssh)
{
        ssh_dispatch_init(ssh, &dispatch_protocol_error);

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

        /* rekeying */
        ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);

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

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 || options.session_type == SESSION_TYPE_NONE) {
                session_closed = 1;
                setproctitle("[stopped mux]");
        }
}

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