source: trunk/third/openssh/clientloop.c @ 18759

/*
 * 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"
RCSID("$OpenBSD: clientloop.c,v 1.104 2002/08/22 19:38:42 stevesk Exp $");

#include "ssh.h"
#include "ssh1.h"
#include "ssh2.h"
#include "xmalloc.h"
#include "packet.h"
#include "buffer.h"
#include "compat.h"
#include "channels.h"
#include "dispatch.h"
#include "buffer.h"
#include "bufaux.h"
#include "key.h"
#include "kex.h"
#include "log.h"
#include "readconf.h"
#include "clientloop.h"
#include "authfd.h"
#include "atomicio.h"
#include "sshtty.h"
#include "misc.h"
#include "readpass.h"

/* import options */
extern Options options;

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

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

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

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

/* Common data for the client loop code. */
static int quit_pending;        /* Set to non-zero to quit the client loop. */
static int escape_char;         /* Escape character. */
static int escape_pending;      /* Last character was the escape character */
static int last_was_cr;         /* Last character was a newline. */
static int exit_status;         /* Used to store the exit status of the command. */
static int stdin_eof;           /* EOF has been encountered on standard error. */
static Buffer stdin_buffer;     /* Buffer for stdin data. */
static Buffer stdout_buffer;    /* Buffer for stdout data. */
static Buffer stderr_buffer;    /* Buffer for stderr data. */
static u_long stdin_bytes, stdout_bytes, stderr_bytes;
static u_int buffer_high;/* Soft max buffer size. */
static int connection_in;       /* Connection to server (input). */
static int connection_out;      /* Connection to server (output). */
static int need_rekeying;       /* Set to non-zero if rekeying is requested. */
static int session_closed = 0;  /* In SSH2: login session closed. */

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

/*XXX*/
extern Kex *xxx_kex;

/* Restores stdin to blocking mode. */

static void
leave_non_blocking(void)
{
        if (in_non_blocking_mode) {
                (void) fcntl(fileno(stdin), F_SETFL, 0);
                in_non_blocking_mode = 0;
                fatal_remove_cleanup((void (*) (void *)) leave_non_blocking, NULL);
        }
}

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

static void
enter_non_blocking(void)
{
        in_non_blocking_mode = 1;
        (void) fcntl(fileno(stdin), F_SETFL, O_NONBLOCK);
        fatal_add_cleanup((void (*) (void *)) leave_non_blocking, NULL);
}

/*
 * Signal handler for the window change signal (SIGWINCH).  This just sets a
 * flag indicating that the window has changed.
 */

static void
window_change_handler(int sig)
{
        received_window_change_signal = 1;
        signal(SIGWINCH, window_change_handler);
}

/*
 * Signal handler for signals that cause the program to terminate.  These
 * signals must be trapped to restore terminal modes.
 */

static void
signal_handler(int sig)
{
        received_signal = sig;
        quit_pending = 1;
}

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

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

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

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

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

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


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

static void
client_make_packets_from_stdin_data(void)
{
        u_int len;

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

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

static void
client_check_window_change(void)
{
        struct winsize ws;

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

        if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
                return;

        debug2("client_check_window_change: changed");

        if (compat20) {
                channel_request_start(session_ident, "window-change", 0);
                packet_put_int(ws.ws_col);
                packet_put_int(ws.ws_row);
                packet_put_int(ws.ws_xpixel);
                packet_put_int(ws.ws_ypixel);
                packet_send();
        } else {
                packet_start(SSH_CMSG_WINDOW_SIZE);
                packet_put_int(ws.ws_row);
                packet_put_int(ws.ws_col);
                packet_put_int(ws.ws_xpixel);
                packet_put_int(ws.ws_ypixel);
                packet_send();
        }
}

/*
 * Waits until the client can do something (some data becomes available on
 * one of the file descriptors).
 */

static void
client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
    int *maxfdp, int *nallocp, int rekeying)
{
        /* Add any selections by the channel mechanism. */
        channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, rekeying);

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

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

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

        /*
         * Wait for something to happen.  This will suspend the process until
         * some selected descriptor can be read, written, or has some other
         * event pending. Note: if you want to implement SSH_MSG_IGNORE
         * messages to fool traffic analysis, this might be the place to do
         * it: just have a random timeout for the select, and send a random
         * SSH_MSG_IGNORE packet when the timeout expires.
         */

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

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

                if (errno == EINTR)
                        return;
                /* Note: we might still have data in the buffers. */
                snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
                buffer_append(&stderr_buffer, buf, strlen(buf));
                quit_pending = 1;
        }
}

static void
client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr)
{
        struct winsize oldws, newws;

        /* Flush stdout and stderr buffers. */
        if (buffer_len(bout) > 0)
                atomicio(write, fileno(stdout), buffer_ptr(bout), buffer_len(bout));
        if (buffer_len(berr) > 0)
                atomicio(write, fileno(stderr), buffer_ptr(berr), buffer_len(berr));

        leave_raw_mode();

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

        /* Save old window size. */
        ioctl(fileno(stdin), TIOCGWINSZ, &oldws);

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

        /* Check if the window size has changed. */
        if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 &&
            (oldws.ws_row != newws.ws_row ||
            oldws.ws_col != newws.ws_col ||
            oldws.ws_xpixel != newws.ws_xpixel ||
            oldws.ws_ypixel != newws.ws_ypixel))
                received_window_change_signal = 1;

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

        enter_raw_mode();
}

static void
client_process_net_input(fd_set * readset)
{
        int len;
        char buf[8192];

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

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

static void
process_cmdline(void)
{
        void (*handler)(int);
        char *s, *cmd;
        u_short fwd_port, fwd_host_port;
        char buf[1024], sfwd_port[6], sfwd_host_port[6];
        int local = 0;

        leave_raw_mode();
        handler = signal(SIGINT, SIG_IGN);
        cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
        if (s == NULL)
                goto out;
        while (*s && isspace(*s))
                s++;
        if (*s == 0)
                goto out;
        if (strlen(s) < 2 || s[0] != '-' || !(s[1] == 'L' || s[1] == 'R')) {
                log("Invalid command.");
                goto out;
        }
        if (s[1] == 'L')
                local = 1;
        if (!local && !compat20) {
                log("Not supported for SSH protocol version 1.");
                goto out;
        }
        s += 2;
        while (*s && isspace(*s))
                s++;

        if (sscanf(s, "%5[0-9]:%255[^:]:%5[0-9]",
            sfwd_port, buf, sfwd_host_port) != 3 &&
            sscanf(s, "%5[0-9]/%255[^/]/%5[0-9]",
            sfwd_port, buf, sfwd_host_port) != 3) {
                log("Bad forwarding specification.");
                goto out;
        }
        if ((fwd_port = a2port(sfwd_port)) == 0 ||
            (fwd_host_port = a2port(sfwd_host_port)) == 0) {
                log("Bad forwarding port(s).");
                goto out;
        }
        if (local) {
                if (channel_setup_local_fwd_listener(fwd_port, buf,
                    fwd_host_port, options.gateway_ports) < 0) {
                        log("Port forwarding failed.");
                        goto out;
                }
        } else
                channel_request_remote_forwarding(fwd_port, buf,
                    fwd_host_port);
        log("Forwarding port.");
out:
        signal(SIGINT, handler);
        enter_raw_mode();
        if (cmd)
                xfree(cmd);
}

/* process the characters one by one */
static int
process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
{
        char string[1024];
        pid_t pid;
        int bytes = 0;
        u_int i;
        u_char ch;
        char *s;

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

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

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

                                quit_pending = 1;
                                return -1;

                        case 'Z' - 64:
                                /* Suspend the program. */
                                /* Print a message to that effect to the user. */
                                snprintf(string, sizeof string, "%c^Z [suspend ssh]\r\n", escape_char);
                                buffer_append(berr, string, strlen(string));

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

                                /* We have been continued. */
                                continue;

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

                        case '&':
                                /*
                                 * Detach the program (continue to serve connections,
                                 * but put in background and no more new connections).
                                 */
                                /* Restore tty modes. */
                                leave_raw_mode();

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

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

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

                        case '?':
                                snprintf(string, sizeof string,
"%c?\r\n\
Supported escape sequences:\r\n\
%c.  - terminate connection\r\n\
%cC  - open a command line\r\n\
%cR  - Request rekey (SSH protocol 2 only)\r\n\
%c^Z - suspend ssh\r\n\
%c#  - list forwarded connections\r\n\
%c&  - background ssh (when waiting for connections to terminate)\r\n\
%c?  - this message\r\n\
%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, escape_char, escape_char,
                                    escape_char, escape_char, escape_char, escape_char,
                                    escape_char, escape_char);
                                buffer_append(berr, string, strlen(string));
                                continue;

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

                        case 'C':
                                process_cmdline();
                                continue;

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

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

static void
client_process_input(fd_set * readset)
{
        int len;
        char buf[8192];

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

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

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

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

static void
client_process_buffered_input_packets(void)
{
        dispatch_run(DISPATCH_NONBLOCK, &quit_pending, compat20 ? xxx_kex : NULL);
}

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

static int
simple_escape_filter(Channel *c, char *buf, int len)
{
        /* XXX we assume c->extended is writeable */
        return process_escapes(&c->input, &c->output, &c->extended, buf, len);
}

static void
client_channel_closed(int id, void *arg)
{
        if (id != session_ident)
                error("client_channel_closed: id %d != session_ident %d",
                    id, session_ident);
        channel_cancel_cleanup(id);
        session_closed = 1;
        if (in_raw_mode())
                leave_raw_mode();
}

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

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

        debug("Entering interactive session.");

        start_time = get_current_time();

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

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

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

        client_init_dispatch();

        /* Set signal handlers to restore non-blocking mode.  */
        signal(SIGINT, signal_handler);
        signal(SIGQUIT, signal_handler);
        signal(SIGTERM, signal_handler);
        if (have_pty)
                signal(SIGWINCH, window_change_handler);

        if (have_pty)
                enter_raw_mode();

        if (compat20) {
                session_ident = ssh2_chan_id;
                if (escape_char != SSH_ESCAPECHAR_NONE)
                        channel_register_filter(session_ident,
                            simple_escape_filter);
                if (session_ident != -1)
                        channel_register_cleanup(session_ident,
                            client_channel_closed);
        } else {
                /* Check if we should immediately send eof on stdin. */
                client_check_initial_eof_on_stdin();
        }

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

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

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

                rekeying = (xxx_kex != NULL && !xxx_kex->done);

                if (rekeying) {
                        debug("rekeying in progress");
                } else {
                        /*
                         * Make packets of buffered stdin data, and buffer
                         * them for sending to the server.
                         */
                        if (!compat20)
                                client_make_packets_from_stdin_data();

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

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

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

                if (quit_pending)
                        break;

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

                        if (need_rekeying) {
                                debug("user requests rekeying");
                                xxx_kex->done = 0;
                                kex_send_kexinit(xxx_kex);
                                need_rekeying = 0;
                        }
                }

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

                if (quit_pending)
                        break;

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

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

        /* Terminate the session. */

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

        channel_free_all();

        if (have_pty)
                leave_raw_mode();

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

        if (received_signal) {
                if (in_non_blocking_mode)       /* XXX */
                        leave_non_blocking();
                fatal("Killed by signal %d.", (int) received_signal);
        }

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

        /* Output any buffered data for stdout. */
        while (buffer_len(&stdout_buffer) > 0) {
                len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
                    buffer_len(&stdout_buffer));
                if (len <= 0) {
                        error("Write failed flushing stdout buffer.");
                        break;
                }
                buffer_consume(&stdout_buffer, len);
                stdout_bytes += len;
        }

        /* Output any buffered data for stderr. */
        while (buffer_len(&stderr_buffer) > 0) {
                len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
                    buffer_len(&stderr_buffer));
                if (len <= 0) {
                        error("Write failed flushing stderr buffer.");
                        break;
                }
                buffer_consume(&stderr_buffer, len);
                stderr_bytes += len;
        }

        /* Clear and free any buffers. */
        memset(buf, 0, sizeof(buf));
        buffer_free(&stdin_buffer);
        buffer_free(&stdout_buffer);
        buffer_free(&stderr_buffer);

        /* Report bytes transferred, and transfer rates. */
        total_time = get_current_time() - start_time;
        debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds",
            stdin_bytes, stdout_bytes, stderr_bytes, total_time);
        if (total_time > 0)
                debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f",
                    stdin_bytes / total_time, stdout_bytes / total_time,
                    stderr_bytes / total_time);

        /* Return the exit status of the program. */
        debug("Exit status %d", exit_status);
        return exit_status;
}

/*********/

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

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

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

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

        sock = channel_connect_by_listen_address(listen_port);
        if (sock < 0) {
                xfree(originator_address);
                xfree(listen_address);
                return NULL;
        }
        c = channel_new("forwarded-tcpip",
            SSH_CHANNEL_CONNECTING, sock, sock, -1,
            CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
            xstrdup(originator_address), 1);
        xfree(originator_address);
        xfree(listen_address);
        return c;
}

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

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

static Channel *
client_request_agent(const char *request_type, int rchan)
{
        Channel *c = NULL;
        int 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;
        }
        sock =  ssh_get_authentication_socket();
        if (sock < 0)
                return NULL;
        c = channel_new("authentication agent connection",
            SSH_CHANNEL_OPEN, sock, sock, -1,
            CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
            xstrdup("authentication agent connection"), 1);
        c->force_drain = 1;
        return c;
}

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

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

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

        if (strcmp(ctype, "forwarded-tcpip") == 0) {
                c = client_request_forwarded_tcpip(ctype, rchan);
        } else if (strcmp(ctype, "x11") == 0) {
                c = client_request_x11(ctype, rchan);
        } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
                c = client_request_agent(ctype, rchan);
        }
/* XXX duplicate : */
        if (c != NULL) {
                debug("confirm %s", ctype);
                c->remote_id = rchan;
                c->remote_window = rwindow;
                c->remote_maxpacket = rmaxpack;
                if (c->type != SSH_CHANNEL_CONNECTING) {
                        packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
                        packet_put_int(c->remote_id);
                        packet_put_int(c->self);
                        packet_put_int(c->local_window);
                        packet_put_int(c->local_maxpacket);
                        packet_send();
                }
        } else {
                debug("failure %s", ctype);
                packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
                packet_put_int(rchan);
                packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
                if (!(datafellows & SSH_BUG_OPENFAILURE)) {
                        packet_put_cstring("open failed");
                        packet_put_cstring("");
                }
                packet_send();
        }
        xfree(ctype);
}
static void
client_input_channel_req(int type, u_int32_t seq, void *ctxt)
{
        Channel *c = NULL;
        int id, reply, success = 0;
        char *rtype;

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

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

        if (session_ident == -1) {
                error("client_input_channel_req: no channel %d", session_ident);
        } else if (id != session_ident) {
                error("client_input_channel_req: channel %d: wrong channel: %d",
                    session_ident, id);
        }
        c = channel_lookup(id);
        if (c == NULL) {
                error("client_input_channel_req: channel %d: unknown channel", id);
        } else if (strcmp(rtype, "exit-status") == 0) {
                success = 1;
                exit_status = packet_get_int();
                packet_check_eom();
        }
        if (reply) {
                packet_start(success ?
                    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
                packet_put_int(c->remote_id);
                packet_send();
        }
        xfree(rtype);
}
static void
client_input_global_request(int type, u_int32_t seq, void *ctxt)
{
        char *rtype;
        int want_reply;
        int success = 0;

        rtype = packet_get_string(NULL);
        want_reply = packet_get_char();
        debug("client_input_global_request: rtype %s want_reply %d", rtype, want_reply);
        if (want_reply) {
                packet_start(success ?
                    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
                packet_send();
                packet_write_wait();
        }
        xfree(rtype);
}

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

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

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

        /* global request reply messages */
        dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
        dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
}
static void
client_init_dispatch_13(void)
{
        dispatch_init(NULL);
        dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
        dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
        dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
        dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
        dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
        dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
        dispatch_set(SSH_SMSG_EXITSTATUS, &client_input_exit_status);
        dispatch_set(SSH_SMSG_STDERR_DATA, &client_input_stderr_data);
        dispatch_set(SSH_SMSG_STDOUT_DATA, &client_input_stdout_data);

        dispatch_set(SSH_SMSG_AGENT_OPEN, options.forward_agent ?
            &auth_input_open_request : &deny_input_open);
        dispatch_set(SSH_SMSG_X11_OPEN, options.forward_x11 ?
            &x11_input_open : &deny_input_open);
}
static void
client_init_dispatch_15(void)
{
        client_init_dispatch_13();
        dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
        dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, & channel_input_oclose);
}
static void
client_init_dispatch(void)
{
        if (compat20)
                client_init_dispatch_20();
        else if (compat13)
                client_init_dispatch_13();
        else
                client_init_dispatch_15();
}