mutt_tunnel.c

/**
 * @file
 * Support for network tunnelling
 *
 * @authors
 * Copyright (C) 2000 Manoj Kasichainula <manoj@io.com>
 * Copyright (C) 2001,2005 Brendan Cully <brendan@kublai.com>
 *
 * @copyright
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"
#include <errno.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "mutt.h"
#include "mutt_tunnel.h"
#include "account.h"
#include "globals.h"
#include "lib/lib.h"
#include "mutt_socket.h"
#include "protos.h"

/**
 * struct TunnelData - A network tunnel (pair of sockets)
 */
struct TunnelData
{
  pid_t pid;
  int readfd;
  int writefd;
};

static int tunnel_socket_open(struct Connection *conn)
{
  struct TunnelData *tunnel = NULL;
  int pid;
  int rc;
  int pin[2], pout[2];
  int devnull;

  tunnel = safe_malloc(sizeof(struct TunnelData));
  conn->sockdata = tunnel;

  mutt_message(_("Connecting with \"%s\"..."), Tunnel);

  if ((rc = pipe(pin)) == -1)
  {
    mutt_perror("pipe");
    FREE(&conn->sockdata);
    return -1;
  }
  if ((rc = pipe(pout)) == -1)
  {
    mutt_perror("pipe");
    close(pin[0]);
    close(pin[1]);
    FREE(&conn->sockdata);
    return -1;
  }

  mutt_block_signals_system();
  if ((pid = fork()) == 0)
  {
    mutt_unblock_signals_system(0);
    devnull = open("/dev/null", O_RDWR);
    if (devnull < 0 || dup2(pout[0], STDIN_FILENO) < 0 ||
        dup2(pin[1], STDOUT_FILENO) < 0 || dup2(devnull, STDERR_FILENO) < 0)
      _exit(127);
    close(pin[0]);
    close(pin[1]);
    close(pout[0]);
    close(pout[1]);
    close(devnull);

    /* Don't let the subprocess think it can use the controlling tty */
    setsid();

    execle(EXECSHELL, "sh", "-c", Tunnel, NULL, mutt_envlist());
    _exit(127);
  }
  mutt_unblock_signals_system(1);

  if (pid == -1)
  {
    mutt_perror("fork");
    close(pin[0]);
    close(pin[1]);
    close(pout[0]);
    close(pout[1]);
    FREE(&conn->sockdata);
    return -1;
  }
  if (close(pin[1]) < 0 || close(pout[0]) < 0)
    mutt_perror("close");

  fcntl(pin[0], F_SETFD, FD_CLOEXEC);
  fcntl(pout[1], F_SETFD, FD_CLOEXEC);

  tunnel->readfd = pin[0];
  tunnel->writefd = pout[1];
  tunnel->pid = pid;

  conn->fd = 42; /* stupid hack */

  return 0;
}

static int tunnel_socket_close(struct Connection *conn)
{
  struct TunnelData *tunnel = (struct TunnelData *) conn->sockdata;
  int status;

  close(tunnel->readfd);
  close(tunnel->writefd);
  waitpid(tunnel->pid, &status, 0);
  if (!WIFEXITED(status) || WEXITSTATUS(status))
  {
    mutt_error(_("Tunnel to %s returned error %d (%s)"), conn->account.host,
               WEXITSTATUS(status), NONULL(mutt_strsysexit(WEXITSTATUS(status))));
    mutt_sleep(2);
  }
  FREE(&conn->sockdata);

  return 0;
}

static int tunnel_socket_read(struct Connection *conn, char *buf, size_t len)
{
  struct TunnelData *tunnel = (struct TunnelData *) conn->sockdata;
  int rc;

  rc = read(tunnel->readfd, buf, len);
  if (rc == -1)
  {
    mutt_error(_("Tunnel error talking to %s: %s"), conn->account.host, strerror(errno));
    mutt_sleep(1);
  }

  return rc;
}

static int tunnel_socket_write(struct Connection *conn, const char *buf, size_t len)
{
  struct TunnelData *tunnel = (struct TunnelData *) conn->sockdata;
  int rc;

  rc = write(tunnel->writefd, buf, len);
  if (rc == -1)
  {
    mutt_error(_("Tunnel error talking to %s: %s"), conn->account.host, strerror(errno));
    mutt_sleep(1);
  }

  return rc;
}

static int tunnel_socket_poll(struct Connection *conn, time_t wait_secs)
{
  struct TunnelData *tunnel = (struct TunnelData *) conn->sockdata;
  int ofd;
  int rc;

  ofd = conn->fd;
  conn->fd = tunnel->readfd;
  rc = raw_socket_poll(conn, wait_secs);
  conn->fd = ofd;

  return rc;
}

int mutt_tunnel_socket_setup(struct Connection *conn)
{
  conn->conn_open = tunnel_socket_open;
  conn->conn_close = tunnel_socket_close;
  conn->conn_read = tunnel_socket_read;
  conn->conn_write = tunnel_socket_write;
  conn->conn_poll = tunnel_socket_poll;

  return 0;
}