/*

 * Dropbear SSH

 * 

 * Copyright (c) 2002,2003 Matt Johnston

 * Copyright (c) 2004 by Mihnea Stoenescu

 * All rights reserved.

 * 

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 * 

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE. */

#include "includes.h"

#include "session.h"

#include "dbutil.h"

#include "kex.h"

#include "ssh.h"

#include "packet.h"

#include "tcpfwd.h"

#include "channel.h"

#include "dbrandom.h"

#include "service.h"

#include "runopts.h"

#include "chansession.h"

#include "agentfwd.h"

#include "crypto_desc.h"

#include "netio.h"

static void cli_remoteclosed(void) ATTRIB_NORETURN;

static void cli_sessionloop(void);

static void cli_session_init(pid_t proxy_cmd_pid);

static void cli_finished(void) ATTRIB_NORETURN;

static void recv_msg_service_accept(void);

static void cli_session_cleanup(void);

static void recv_msg_global_request_cli(void);

static void cli_algos_initialise(void);

struct clientsession cli_ses; /* GLOBAL */

/* Sorted in decreasing frequency will be more efficient - data and window

 * should be first */

static const packettype cli_packettypes[] = {

  /* TYPE, FUNCTION */

  {SSH_MSG_CHANNEL_DATA, recv_msg_channel_data},

  {SSH_MSG_CHANNEL_EXTENDED_DATA, recv_msg_channel_extended_data},

  {SSH_MSG_CHANNEL_WINDOW_ADJUST, recv_msg_channel_window_adjust},

  {SSH_MSG_USERAUTH_FAILURE, recv_msg_userauth_failure}, /* client */

  {SSH_MSG_USERAUTH_SUCCESS, recv_msg_userauth_success}, /* client */

  {SSH_MSG_KEXINIT, recv_msg_kexinit},

  {SSH_MSG_KEXDH_REPLY, recv_msg_kexdh_reply}, /* client */

  {SSH_MSG_NEWKEYS, recv_msg_newkeys},

  {SSH_MSG_SERVICE_ACCEPT, recv_msg_service_accept}, /* client */

  {SSH_MSG_CHANNEL_REQUEST, recv_msg_channel_request},

  {SSH_MSG_CHANNEL_OPEN, recv_msg_channel_open},

  {SSH_MSG_CHANNEL_EOF, recv_msg_channel_eof},

  {SSH_MSG_CHANNEL_CLOSE, recv_msg_channel_close},

  {SSH_MSG_CHANNEL_OPEN_CONFIRMATION, recv_msg_channel_open_confirmation},

  {SSH_MSG_CHANNEL_OPEN_FAILURE, recv_msg_channel_open_failure},

  {SSH_MSG_USERAUTH_BANNER, recv_msg_userauth_banner}, /* client */

  {SSH_MSG_USERAUTH_SPECIFIC_60, recv_msg_userauth_specific_60}, /* client */

  {SSH_MSG_GLOBAL_REQUEST, recv_msg_global_request_cli},

  {SSH_MSG_CHANNEL_SUCCESS, ignore_recv_response},

  {SSH_MSG_CHANNEL_FAILURE, ignore_recv_response},

#if DROPBEAR_CLI_REMOTETCPFWD

  {SSH_MSG_REQUEST_SUCCESS, cli_recv_msg_request_success}, /* client */

  {SSH_MSG_REQUEST_FAILURE, cli_recv_msg_request_failure}, /* client */

#else

  /* For keepalive */

  {SSH_MSG_REQUEST_SUCCESS, ignore_recv_response},

  {SSH_MSG_REQUEST_FAILURE, ignore_recv_response},

#endif

  {SSH_MSG_EXT_INFO, recv_msg_ext_info},

  {0, NULL} /* End */

};

static const struct ChanType *cli_chantypes[] = {

#if DROPBEAR_CLI_REMOTETCPFWD

  &cli_chan_tcpremote,

#endif

#if DROPBEAR_CLI_AGENTFWD

  &cli_chan_agent,

#endif

  NULL /* Null termination */

};

void cli_connected(int result, int sock, void* userdata, const char *errstring)

{

  struct sshsession *myses = userdata;

  if (result == DROPBEAR_FAILURE) {

    dropbear_exit("Connect failed: %s", errstring);

  }

  myses->sock_in = myses->sock_out = sock;

  DEBUG1(("cli_connected"))

  ses.socket_prio = DROPBEAR_PRIO_NORMAL;

  /* switches to lowdelay */

  update_channel_prio();

}

void cli_session(int sock_in, int sock_out, struct dropbear_progress_connection *progress, pid_t proxy_cmd_pid) {

  common_session_init(sock_in, sock_out);

  if (progress) {

    connect_set_writequeue(progress, &ses.writequeue);

  }

  chaninitialise(cli_chantypes);

  cli_algos_initialise();

  /* Set up cli_ses vars */

  cli_session_init(proxy_cmd_pid);

  /* Ready to go */

  ses.init_done = 1;

  /* Exchange identification */

  send_session_identification();

  kexfirstinitialise(); /* initialise the kex state */

  send_msg_kexinit();

  session_loop(cli_sessionloop);

  /* Not reached */

}

#if DROPBEAR_KEX_FIRST_FOLLOWS

static void cli_send_kex_first_guess() {

  send_msg_kexdh_init();

}

#endif

static void cli_session_init(pid_t proxy_cmd_pid) {

  cli_ses.state = STATE_NOTHING;

  cli_ses.kex_state = KEX_NOTHING;

  cli_ses.tty_raw_mode = 0;

  cli_ses.winchange = 0;

  /* We store std{in,out,err}'s flags, so we can set them back on exit

   * (otherwise busybox's ash isn't happy */

  cli_ses.stdincopy = dup(STDIN_FILENO);

  cli_ses.stdinflags = fcntl(STDIN_FILENO, F_GETFL, 0);

  cli_ses.stdoutcopy = dup(STDOUT_FILENO);

  cli_ses.stdoutflags = fcntl(STDOUT_FILENO, F_GETFL, 0);

  cli_ses.stderrcopy = dup(STDERR_FILENO);

  cli_ses.stderrflags = fcntl(STDERR_FILENO, F_GETFL, 0);

  cli_ses.retval = EXIT_SUCCESS; /* Assume it's clean if we don't get a

                    specific exit status */

  cli_ses.proxy_cmd_pid = proxy_cmd_pid;

  TRACE(("proxy command PID='%d'", proxy_cmd_pid));

  /* Auth */

  cli_ses.lastprivkey = NULL;

  cli_ses.lastauthtype = 0;

  cli_ses.is_trivial_auth = 1;

  /* For printing "remote host closed" for the user */

  ses.remoteclosed = cli_remoteclosed;

  ses.extra_session_cleanup = cli_session_cleanup;

  /* packet handlers */

  ses.packettypes = cli_packettypes;

  ses.isserver = 0;

#if DROPBEAR_KEX_FIRST_FOLLOWS

  ses.send_kex_first_guess = cli_send_kex_first_guess;

#endif

}

static void send_msg_service_request(const char* servicename) {

  TRACE(("enter send_msg_service_request: servicename='%s'", servicename))

  CHECKCLEARTOWRITE();

  buf_putbyte(ses.writepayload, SSH_MSG_SERVICE_REQUEST);

  buf_putstring(ses.writepayload, servicename, strlen(servicename));

  encrypt_packet();

  TRACE(("leave send_msg_service_request"))

}

static void recv_msg_service_accept(void) {

  /* do nothing, if it failed then the server MUST have disconnected */

}

/* This function drives the progress of the session - it initiates KEX,

 * service, userauth and channel requests */

static void cli_sessionloop() {

  TRACE2(("enter cli_sessionloop"))

  if (ses.lastpacket == 0) {

    TRACE2(("exit cli_sessionloop: no real packets yet"))

    return;

  }

  if (ses.lastpacket == SSH_MSG_KEXINIT && cli_ses.kex_state == KEX_NOTHING) {

    /* We initiate the KEXDH. If DH wasn't the correct type, the KEXINIT

     * negotiation would have failed. */

    if (!ses.kexstate.our_first_follows_matches) {

      send_msg_kexdh_init();

    }

    cli_ses.kex_state = KEXDH_INIT_SENT;      

    TRACE(("leave cli_sessionloop: done with KEXINIT_RCVD"))

    return;

  }

  /* A KEX has finished, so we should go back to our KEX_NOTHING state */

  if (cli_ses.kex_state != KEX_NOTHING && ses.kexstate.sentnewkeys) {

    cli_ses.kex_state = KEX_NOTHING;

  }

  /* We shouldn't do anything else if a KEX is in progress */

  if (cli_ses.kex_state != KEX_NOTHING) {

    TRACE(("leave cli_sessionloop: kex_state != KEX_NOTHING"))

    return;

  }

  if (ses.kexstate.donefirstkex == 0) {

    /* We might reach here if we have partial packet reads or have

     * received SSG_MSG_IGNORE etc. Just skip it */

    TRACE2(("donefirstkex false\n"))

    return;

  }

  switch (cli_ses.state) {

    case STATE_NOTHING:

      /* We've got the transport layer sorted, we now need to request

       * userauth */

      send_msg_service_request(SSH_SERVICE_USERAUTH);

      /* We aren't using any "implicit server authentication" methods,

      so don't need to wait for a response for SSH_SERVICE_USERAUTH

      before sending the auth messages (rfc4253 10) */

      cli_auth_getmethods();

      cli_ses.state = USERAUTH_REQ_SENT;

      TRACE(("leave cli_sessionloop: sent userauth methods req"))

      return;

    case USERAUTH_REQ_SENT:

      TRACE(("leave cli_sessionloop: waiting, req_sent"))

      return;

    case USERAUTH_FAIL_RCVD:

      if (cli_auth_try() == DROPBEAR_FAILURE) {

        dropbear_exit("No auth methods could be used.");

      }

      cli_ses.state = USERAUTH_REQ_SENT;

      TRACE(("leave cli_sessionloop: cli_auth_try"))

      return;

    case USERAUTH_SUCCESS_RCVD:

#ifndef DISABLE_SYSLOG

      if (opts.usingsyslog) {

        dropbear_log(LOG_INFO, "Authentication succeeded.");

      }

#endif

      if (cli_opts.backgrounded) {

        int devnull;

        /* keeping stdin open steals input from the terminal and

           is confusing, though stdout/stderr could be useful. */

        devnull = open(DROPBEAR_PATH_DEVNULL, O_RDONLY);

        if (devnull < 0) {

          dropbear_exit("Opening /dev/null: %d %s",

              errno, strerror(errno));

        }

        dup2(devnull, STDIN_FILENO);

        if (daemon(0, 1) < 0) {

          dropbear_exit("Backgrounding failed: %d %s", 

              errno, strerror(errno));

        }

      }

#if DROPBEAR_CLI_NETCAT

      if (cli_opts.netcat_host) {

        cli_send_netcat_request();

      } else 

#endif

      if (!cli_opts.no_cmd) {

        cli_send_chansess_request();

      }

#if DROPBEAR_CLI_LOCALTCPFWD

      setup_localtcp();

#endif

#if DROPBEAR_CLI_REMOTETCPFWD

      setup_remotetcp();

#endif

      TRACE(("leave cli_sessionloop: running"))

      cli_ses.state = SESSION_RUNNING;

      return;

    case SESSION_RUNNING:

      if (ses.chancount < 1 && !cli_opts.no_cmd) {

        cli_finished();

      }

      if (cli_ses.winchange) {

        cli_chansess_winchange();

      }

      return;

    /* XXX more here needed */

  default:

    break;

  }

  TRACE2(("leave cli_sessionloop: fell out"))

}

void kill_proxy_command(void) {

  /*

   * Send SIGHUP to proxy command if used. We don't wait() in

   * case it hangs and instead rely on init to reap the child

   */

  if (cli_ses.proxy_cmd_pid > 1) {

    TRACE(("killing proxy command with PID='%d'", cli_ses.proxy_cmd_pid));

    kill(cli_ses.proxy_cmd_pid, SIGHUP);

  }

}

static void cli_session_cleanup(void) {

  if (!ses.init_done) {

    return;

  }

  kill_proxy_command();

  /* Set std{in,out,err} back to non-blocking - busybox ash dies nastily if

   * we don't revert the flags */

  /* Ignore return value since there's nothing we can do */

  (void)fcntl(cli_ses.stdincopy, F_SETFL, cli_ses.stdinflags);

  (void)fcntl(cli_ses.stdoutcopy, F_SETFL, cli_ses.stdoutflags);

  (void)fcntl(cli_ses.stderrcopy, F_SETFL, cli_ses.stderrflags);

  /* Don't leak */

  m_close(cli_ses.stdincopy);

  m_close(cli_ses.stdoutcopy);

  m_close(cli_ses.stderrcopy);

  cli_tty_cleanup();

  if (cli_ses.server_sig_algs) {

    buf_free(cli_ses.server_sig_algs);

  }

}

static void cli_finished() {

  TRACE(("cli_finished()"))

  session_cleanup();

  fprintf(stderr, "Connection to %s@%s:%s closed.\n", cli_opts.username,

      cli_opts.remotehost, cli_opts.remoteport);

  exit(cli_ses.retval);

}

/* called when the remote side closes the connection */

static void cli_remoteclosed() {

  /* XXX TODO perhaps print a friendlier message if we get this but have

   * already sent/received disconnect message(s) ??? */

  m_close(ses.sock_in);

  m_close(ses.sock_out);

  ses.sock_in = -1;

  ses.sock_out = -1;

  dropbear_exit("Remote closed the connection");

}

/* Operates in-place turning dirty (untrusted potentially containing control

 * characters) text into clean text. 

 * Note: this is safe only with ascii - other charsets could have problems. */

void cleantext(char* dirtytext) {

  unsigned int i, j;

  char c;

  j = 0;

  for (i = 0; dirtytext[i] != '\0'; i++) {

    c = dirtytext[i];

    /* We can ignore '\r's */

    if ( (c >= ' ' && c <= '~') || c == '\n' || c == '\t') {

      dirtytext[j] = c;

      j++;

    }

  }

  /* Null terminate */

  dirtytext[j] = '\0';

}

static void recv_msg_global_request_cli(void) {

  unsigned int wantreply = 0;

  buf_eatstring(ses.payload);

  wantreply = buf_getbool(ses.payload);

  TRACE(("recv_msg_global_request_cli: want_reply: %u", wantreply));

  if (wantreply) {

    /* Send a proper rejection */

    send_msg_request_failure();

  }

}

void cli_dropbear_exit(int exitcode, const char* format, va_list param) {

  char exitmsg[400];

  char fullmsg[550];

  /* Note that exit message must be rendered before session cleanup */

  /* Render the formatted exit message */

  vsnprintf(exitmsg, sizeof(exitmsg), format, param);

  TRACE(("Exited, cleaning up: %s", exitmsg))

  /* Add the prefix depending on session/auth state */

  if (!ses.init_done) {

    snprintf(fullmsg, sizeof(fullmsg), "Exited: %s", exitmsg);

  } else {

    snprintf(fullmsg, sizeof(fullmsg), 

        "Connection to %s@%s:%s exited: %s", 

        cli_opts.username, cli_opts.remotehost, 

        cli_opts.remoteport, exitmsg);

  }

  /* Do the cleanup first, since then the terminal will be reset */

  session_cleanup();

#if DROPBEAR_FUZZ

    if (fuzz.do_jmp) {

        longjmp(fuzz.jmp, 1);

    }

#endif

  /* Avoid printing onwards from terminal cruft */

  fprintf(stderr, "\n");

  dropbear_log(LOG_INFO, "%s", fullmsg);

  exit(exitcode);

}

void cli_dropbear_log(int priority, const char* format, va_list param) {

  char printbuf[1024];

  const char *name;

  name = cli_opts.progname;

  if (!name) {

    name = "dbclient";

  }

  vsnprintf(printbuf, sizeof(printbuf), format, param);

#ifndef DISABLE_SYSLOG

  if (opts.usingsyslog) {

    syslog(priority, "%s", printbuf);

  }

#endif

  fprintf(stderr, "%s: %s\n", name, printbuf);

  fflush(stderr);

}

static void cli_algos_initialise(void) {

  algo_type *algo;

  for (algo = sshkex; algo->name; algo++) {

    if (strcmp(algo->name, SSH_STRICT_KEX_S) == 0) {

      algo->usable = 0;

    }

  }

}