/*

 * 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 "packet.h"

#include "buffer.h"

#include "session.h"

#include "dbutil.h"

#include "channel.h"

#include "ssh.h"

#include "runopts.h"

#include "termcodes.h"

#include "chansession.h"

#include "agentfwd.h"

static void cli_closechansess(const struct Channel *channel);

static int cli_initchansess(struct Channel *channel);

static void cli_chansessreq(struct Channel *channel);

static void send_chansess_pty_req(const struct Channel *channel);

static void send_chansess_shell_req(const struct Channel *channel);

static void cli_escape_handler(const struct Channel *channel, const unsigned char* buf, int *len);

static int cli_init_netcat(struct Channel *channel);

static void cli_tty_setup(void);

const struct ChanType clichansess = {

  "session", /* name */

  cli_initchansess, /* inithandler */

  NULL, /* checkclosehandler */

  cli_chansessreq, /* reqhandler */

  cli_closechansess, /* closehandler */

  NULL, /* cleanup */

};

static void cli_chansessreq(struct Channel *channel) {

  char* type = NULL;

  int wantreply;

  TRACE(("enter cli_chansessreq"))

  type = buf_getstring(ses.payload, NULL);

  wantreply = buf_getbool(ses.payload);

  if (strcmp(type, "exit-status") == 0) {

    cli_ses.retval = buf_getint(ses.payload);

    TRACE(("got exit-status of '%d'", cli_ses.retval))

  } else if (strcmp(type, "exit-signal") == 0) {

    TRACE(("got exit-signal, ignoring it"))

  } else {

    TRACE(("unknown request '%s'", type))

    if (wantreply) {

      send_msg_channel_failure(channel);

    }

    goto out;

  }

out:

  m_free(type);

}

/* If the main session goes, we close it up */

static void cli_closechansess(const struct Channel *UNUSED(channel)) {

  cli_tty_cleanup(); /* Restore tty modes etc */

  /* This channel hasn't gone yet, so we have > 1 */

  if (ses.chancount > 1) {

    dropbear_log(LOG_INFO, "Waiting for other channels to close...");

  }

}

/* Taken from OpenSSH's sshtty.c:

 * RCSID("OpenBSD: sshtty.c,v 1.5 2003/09/19 17:43:35 markus Exp "); */

static void cli_tty_setup() {

  struct termios tio;

  TRACE(("enter cli_pty_setup"))

  if (cli_ses.tty_raw_mode == 1) {

    TRACE(("leave cli_tty_setup: already in raw mode!"))

    return;

  }

  if (tcgetattr(STDIN_FILENO, &tio) == -1) {

    dropbear_exit("Failed to set raw TTY mode");

  }

  /* make a copy */

  cli_ses.saved_tio = tio;

  tio.c_iflag |= IGNPAR;

  tio.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);

#ifdef IUCLC

  tio.c_iflag &= ~IUCLC;

#endif

  tio.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);

#ifdef IEXTEN

  tio.c_lflag &= ~IEXTEN;

#endif

  tio.c_oflag &= ~OPOST;

  tio.c_cc[VMIN] = 1;

  tio.c_cc[VTIME] = 0;

  if (tcsetattr(STDIN_FILENO, TCSADRAIN, &tio) == -1) {

    dropbear_exit("Failed to set raw TTY mode");

  }

  cli_ses.tty_raw_mode = 1;

  TRACE(("leave cli_tty_setup"))

}

void cli_tty_cleanup() {

  TRACE(("enter cli_tty_cleanup"))

  if (cli_ses.tty_raw_mode == 0) {

    TRACE(("leave cli_tty_cleanup: not in raw mode"))

    return;

  }

  if (tcsetattr(STDIN_FILENO, TCSADRAIN, &cli_ses.saved_tio) == -1) {

    dropbear_log(LOG_WARNING, "Failed restoring TTY");

  } else {

    cli_ses.tty_raw_mode = 0; 

  }

  TRACE(("leave cli_tty_cleanup"))

}

static void put_termcodes() {

  struct termios tio;

  unsigned int sshcode;

  const struct TermCode *termcode;

  unsigned int value;

  unsigned int mapcode;

  unsigned int bufpos1, bufpos2;

  TRACE(("enter put_termcodes"))

  if (tcgetattr(STDIN_FILENO, &tio) == -1) {

    dropbear_log(LOG_WARNING, "Failed reading termmodes");

    buf_putint(ses.writepayload, 1); /* Just the terminator */

    buf_putbyte(ses.writepayload, 0); /* TTY_OP_END */

    return;

  }

  bufpos1 = ses.writepayload->pos;

  buf_putint(ses.writepayload, 0); /* A placeholder for the final length */

  /* As with Dropbear server, we ignore baud rates for now */

  for (sshcode = 1; sshcode < MAX_TERMCODE; sshcode++) {

    termcode = &termcodes[sshcode];

    mapcode = termcode->mapcode;

    switch (termcode->type) {

      case TERMCODE_NONE:

        continue;

      case TERMCODE_CONTROLCHAR:

        value = tio.c_cc[mapcode];

        break;

      case TERMCODE_INPUT:

        value = tio.c_iflag & mapcode;

        break;

      case TERMCODE_OUTPUT:

        value = tio.c_oflag & mapcode;

        break;

      case TERMCODE_LOCAL:

        value = tio.c_lflag & mapcode;

        break;

      case TERMCODE_CONTROL:

        value = tio.c_cflag & mapcode;

        break;

      default:

        continue;

    }

    /* If we reach here, we have something to say */

    buf_putbyte(ses.writepayload, sshcode);

    buf_putint(ses.writepayload, value);

  }

  buf_putbyte(ses.writepayload, 0); /* THE END, aka TTY_OP_END */

  /* Put the string length at the start of the buffer */

  bufpos2 = ses.writepayload->pos;

  buf_setpos(ses.writepayload, bufpos1); /* Jump back */

  buf_putint(ses.writepayload, bufpos2 - bufpos1 - 4); /* len(termcodes) */

  buf_setpos(ses.writepayload, bufpos2); /* Back where we were */

  TRACE(("leave put_termcodes"))

}

static void put_winsize() {

  struct winsize ws;

  if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0) {

    /* Some sane defaults */

    ws.ws_row = 25;

    ws.ws_col = 80;

    ws.ws_xpixel = 0;

    ws.ws_ypixel = 0;

  }

  buf_putint(ses.writepayload, ws.ws_col); /* Cols */

  buf_putint(ses.writepayload, ws.ws_row); /* Rows */

  buf_putint(ses.writepayload, ws.ws_xpixel); /* Width */

  buf_putint(ses.writepayload, ws.ws_ypixel); /* Height */

}

static void sigwinch_handler(int UNUSED(unused)) {

  cli_ses.winchange = 1;

}

void cli_chansess_winchange() {

  unsigned int i;

  struct Channel *channel = NULL;

  for (i = 0; i < ses.chansize; i++) {

    channel = ses.channels[i];

    if (channel != NULL && channel->type == &clichansess) {

      CHECKCLEARTOWRITE();

      buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_REQUEST);

      buf_putint(ses.writepayload, channel->remotechan);

      buf_putstring(ses.writepayload, "window-change", 13);

      buf_putbyte(ses.writepayload, 0); /* FALSE says the spec */

      put_winsize();

      encrypt_packet();

    }

  }

  cli_ses.winchange = 0;

}

static void send_chansess_pty_req(const struct Channel *channel) {

  char* term = NULL;

  TRACE(("enter send_chansess_pty_req"))

  start_send_channel_request(channel, "pty-req");

  /* Don't want replies */

  buf_putbyte(ses.writepayload, 0);

  /* Get the terminal */

  term = getenv("TERM");

  if (term == NULL) {

    term = "vt100"; /* Seems a safe default */

  }

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

  /* Window size */

  put_winsize();

  /* Terminal mode encoding */

  put_termcodes();

  encrypt_packet();

  /* Set up a window-change handler */

  if (signal(SIGWINCH, sigwinch_handler) == SIG_ERR) {

    dropbear_exit("Signal error");

  }

  TRACE(("leave send_chansess_pty_req"))

}

static void send_chansess_shell_req(const struct Channel *channel) {

  char* reqtype = NULL;

  TRACE(("enter send_chansess_shell_req"))

  if (cli_opts.cmd) {

    if (cli_opts.is_subsystem) {

      reqtype = "subsystem";

    } else {

      reqtype = "exec";

    }

  } else {

    reqtype = "shell";

  }

  start_send_channel_request(channel, reqtype);

  /* XXX TODO */

  buf_putbyte(ses.writepayload, 0); /* Don't want replies */

  if (cli_opts.cmd) {

    buf_putstring(ses.writepayload, cli_opts.cmd, strlen(cli_opts.cmd));

  }

  encrypt_packet();

  TRACE(("leave send_chansess_shell_req"))

}

/* Shared for normal client channel and netcat-alike */

static int cli_init_stdpipe_sess(struct Channel *channel) {

  channel->writefd = STDOUT_FILENO;

  setnonblocking(STDOUT_FILENO);

  channel->readfd = STDIN_FILENO;

  setnonblocking(STDIN_FILENO);

  channel->errfd = STDERR_FILENO;

  setnonblocking(STDERR_FILENO);

  channel->extrabuf = cbuf_new(opts.recv_window);

  channel->bidir_fd = 0;

  return 0;

}

static int cli_init_netcat(struct Channel *channel) {

  return cli_init_stdpipe_sess(channel);

}

static int cli_initchansess(struct Channel *channel) {

  cli_init_stdpipe_sess(channel);

#if DROPBEAR_CLI_AGENTFWD

  if (cli_opts.agent_fwd) {

    cli_setup_agent(channel);

  }

#endif

  if (cli_opts.wantpty) {

    send_chansess_pty_req(channel);

    channel->prio = DROPBEAR_PRIO_LOWDELAY;

  }

  send_chansess_shell_req(channel);

  if (cli_opts.wantpty) {

    cli_tty_setup();

    channel->read_mangler = cli_escape_handler;

    cli_ses.last_char = '\r';

  }

  return 0; /* Success */

}

#if DROPBEAR_CLI_NETCAT

static const struct ChanType cli_chan_netcat = {

  "direct-tcpip",

  cli_init_netcat, /* inithandler */

  NULL,

  NULL,

  cli_closechansess,

  NULL,

};

void cli_send_netcat_request() {

  const char* source_host = "127.0.0.1";

  const int source_port = 22;

  TRACE(("enter cli_send_netcat_request"))

  cli_opts.wantpty = 0;

  if (send_msg_channel_open_init(STDIN_FILENO, &cli_chan_netcat) 

      == DROPBEAR_FAILURE) {

    dropbear_exit("Couldn't open initial channel");

  }

  buf_putstring(ses.writepayload, cli_opts.netcat_host,

      strlen(cli_opts.netcat_host));

  buf_putint(ses.writepayload, cli_opts.netcat_port);

  /* originator ip - localhost is accurate enough */

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

  buf_putint(ses.writepayload, source_port);

  encrypt_packet();

  TRACE(("leave cli_send_netcat_request"))

}

#endif

void cli_send_chansess_request() {

  TRACE(("enter cli_send_chansess_request"))

  if (send_msg_channel_open_init(STDIN_FILENO, &clichansess) 

      == DROPBEAR_FAILURE) {

    dropbear_exit("Couldn't open initial channel");

  }

  /* No special channel request data */

  encrypt_packet();

  TRACE(("leave cli_send_chansess_request"))

}

/* returns 1 if the character should be consumed, 0 to pass through */

static int

do_escape(unsigned char c) {

  switch (c) {

    case '.':

      dropbear_exit("Terminated");

      return 1;

    case 0x1a:

      /* ctrl-z */

      cli_tty_cleanup();

      kill(getpid(), SIGTSTP);

      /* after continuation */

      cli_tty_setup();

      cli_ses.winchange = 1;

      return 1;

    default:

      return 0;

  }

}

static

void cli_escape_handler(const struct Channel* UNUSED(channel), const unsigned char* buf, int *len) {

  char c;

  int skip_char = 0;

  /* only handle escape characters if they are read one at a time. simplifies 

     the code and avoids nasty people putting ~. at the start of a line to paste  */

  if (*len != 1) {

    cli_ses.last_char = 0x0;

    return;

  }

  c = buf[0];

  if (cli_ses.last_char == DROPBEAR_ESCAPE_CHAR) {

    skip_char = do_escape(c);

    cli_ses.last_char = 0x0;

  } else {

    if (c == DROPBEAR_ESCAPE_CHAR) {

      if (cli_ses.last_char == '\r') {

        cli_ses.last_char = DROPBEAR_ESCAPE_CHAR;

        skip_char = 1;

      } else {

        cli_ses.last_char = 0x0;

      }

    } else {

      cli_ses.last_char = c;

    }

  }

  if (skip_char) {

    *len = 0;

  }

}