path: root/src/msh.c

/**
 * @file msh.c
 * @brief program to launch remote processes through MSH.  This program is
 *          to be started by the MSH Daemon or by any process in the process
 *          subtree having the MSH Daemon as a parent process.
 * @author Sree Harsha Totakura <sreeharsha@totakura.in> 
 */

#include "common.h"
#include <gnunet/gnunet_util_lib.h>
#include "termios.h"
#include "mtypes.h"
#include "util.h"

#define LOG(kind,...)                           \
  GNUNET_log (kind, __VA_ARGS__)

#define LOG_DEBUG(...) LOG(GNUNET_ERROR_TYPE_DEBUG, __VA_ARGS__)

#define LOG_ERROR(...) LOG(GNUNET_ERROR_TYPE_ERROR, __VA_ARGS__)

/**
 * Configuration section for connection to local MSHD
 */
#define MSHD_LOCAL "MSHD-LOCAL"

/**
 * Configuration section for connection to remote MSHD
 */
#define MSHD_REMOTE "MSHD-REMOTE"

/**
 * The message queue for sending messages to the controller service
 */
struct MessageQueue
{
  /**
   * next pointer for DLL
   */
  struct MessageQueue *next;

  /**
   * prev pointer for DLL
   */
  struct MessageQueue *prev;

  /**
   * The message to be sent
   */
  struct GNUNET_MessageHeader *msg;
};


/**
 * Context information for a connection
 */
struct ConnCtx
{
  /**
   * The transmit handle
   */
  struct GNUNET_CLIENT_TransmitHandle *tx;

  /**
   * The client connection handle
   */
  struct GNUNET_CLIENT_Connection *conn;

  /**
   * configuration used to obtain this connection
   */
  struct GNUNET_CONFIGURATION_Handle *cfg;

  /**
   * DLL head for the message queue
   */
   struct MessageQueue *mq_head;

  /**
   * DLL tail for the message queue
   */
   struct MessageQueue *mq_tail;

  /**
   * retry backoff time for this connection
   */
  struct GNUNET_TIME_Relative backoff;
};


/**
 * context for the connection to parent MSHD
 */
static struct ConnCtx ctx_local;

/**
 * context for the connection to remote MSHD
 */
static struct ConnCtx ctx_remote;

/**
 * file handle for the stdin
 */
static struct GNUNET_DISK_FileHandle *fh_stdin;

/**
 * file handle for stdout
 */
static struct GNUNET_DISK_FileHandle *fh_stdout;

/**
 * file handle for stdout
 */
static struct GNUNET_DISK_FileHandle *fh_stderr;

/**
 * The command string (cmd + parameters)
 */
static char *cmdstr;

/**
 * Program help text
 */
static char *help_text = 
    "MSH utility to lauch remote programs\n"
    "Usage: msh <ip-address> <cmd> [arg] ... \n";

/**
 * Buffer used to read data from input streams
 */
static char recv_buf[GNUNET_SERVER_MAX_MESSAGE_SIZE];

/**
 * Handle for a test to check if MSHD is running in a mode accepting remote commands.
 */
struct GNUNET_CLIENT_TestHandle *test;

/**
 * length of the cmdstr
 */
static size_t cmdstr_len;

/**
 * Task to forward stdin to MSHD
 */
static GNUNET_SCHEDULER_TaskIdentifier task_fwd_stdin;

/**
 * Shutdown task to disconnect client connections
 */
static GNUNET_SCHEDULER_TaskIdentifier task_shutdown;

/**
 * flag to indicate successful completion by setting it to GNUNET_OK
 */
static int result;

/**
 * different states
 */
enum State
{
  /**
   * Address lookup of the remote instance
   */
  STATE_LOOKUP,
  
  /**
   * Remote command is delivered to remote MSHD
   */
  STATE_DELIVER_CMD,

  /**
   * Get authorization credential from parent MSHD
   */
  STATE_GET_CRED,

  /**
   * stdin and stdout streams are forwarded to and from the MSHD
   */
  STATE_FORWARD_STREAMS,

} state;


/**
 * Terminal window size information
 */
static struct winsize ws;

/**
 * Terminal settings
 */
static struct termios tio;

/**
 * The ip address of the remote node
 */
static in_addr_t target;

/**
 * The port number where the MSHD is listening on target host
 */
static uint16_t target_port;

/**
 * Do not allocate pseudo-tty
 */
static int disable_pty;

/**
 * Are we capable of allocating pseudo-tty
 */
static int can_pty;

/**
 * Do we need to allocate a pseudo-tty
 */
static int need_pty;

/**
 * Did we set our terminal to raw mode
 */
static int tty_rawed;

/**
 * Destroys a connection context
 *
 * @param ctx connection context
 */
static void
destroy_conn_ctx (struct ConnCtx *ctx)
{
  struct MessageQueue *mq;

  if (NULL != ctx->tx)
  {
    GNUNET_CLIENT_notify_transmit_ready_cancel (ctx->tx);
    ctx->tx = NULL;
  }
  if (NULL != ctx->conn)
  {   
    GNUNET_CLIENT_disconnect (ctx->conn);
    ctx->conn = NULL;
  }
  if (NULL != ctx->cfg)
  {
    GNUNET_CONFIGURATION_destroy (ctx->cfg);
    ctx->cfg = NULL;
  }
  while (NULL != (mq = ctx->mq_head))
  {
    GNUNET_CONTAINER_DLL_remove (ctx->mq_head, ctx->mq_tail, mq);
    GNUNET_free (mq->msg);
    GNUNET_free (mq);
  } 
}


/**
 * Shutdown task.  Disconnect both client connections by destroying both
 * contexts 
 *
 * @param cls NULL
 * @param tc scheduler task context
 */
static void
do_shutdown (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  task_shutdown = GNUNET_SCHEDULER_NO_TASK;
  LOG_DEBUG ("Shutting down\n");
  destroy_conn_ctx (&ctx_local);
  destroy_conn_ctx (&ctx_remote);
  if ( can_pty && tty_rawed )
  {
    if (tcsetattr(0, TCSADRAIN, &tio) == -1)
    {
      GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "tcsetattr");
      LOG_ERROR ("Failed to set terminal back from raw mode.  "
                 "The terminal may behave wierdly\n");
    }
  }
  if (NULL != fh_stdin)
    GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fh_stdin));
  if (NULL != fh_stdout)
    GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fh_stdout));
  if (NULL != fh_stderr)
    GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fh_stderr));
}


/**
 * Function called to notify a client about the connection
 * begin ready to queue more data.  "buf" will be
 * NULL and "size" zero if the connection was closed for
 * writing in the meantime.
 *
 * @param cls closure
 * @param size number of bytes available in buf
 * @param buf where the callee should write the message
 * @return number of bytes written to buf
 */
static size_t
conn_transmit_ready (void *cls, size_t size, void *buf)
{
  struct ConnCtx *ctx = cls;
  struct MessageQueue *mq;
  uint16_t msg_size;
  size_t wrote;

  wrote = 0;
  GNUNET_assert (NULL != ctx->tx);
  ctx->tx = NULL;
  if ((0 == size) && (NULL == buf))
  {
    LOG_ERROR ("Connection to MSHD broken\n");
    destroy_conn_ctx (ctx);
    return 0;
  }
  mq = ctx->mq_head;
  GNUNET_assert (NULL != mq);
  if ((0 == size) || (NULL == buf))
  {
    LOG_DEBUG ("Message sending timed out -- retrying\n");
    ctx->backoff = GNUNET_TIME_STD_BACKOFF (ctx->backoff);
    ctx->tx =
        GNUNET_CLIENT_notify_transmit_ready (ctx->conn, ntohs (mq->msg->size),
                                             ctx->backoff, GNUNET_NO,
                                             &conn_transmit_ready,
                                             ctx);
        
    return 0;
  }
  ctx->backoff = GNUNET_TIME_UNIT_ZERO;
  msg_size = ntohs (mq->msg->size);
  GNUNET_assert ( msg_size <= size);
  (void) memcpy (buf, mq->msg, msg_size);
  wrote = msg_size;
  LOG_DEBUG ("Message of type %u, size %u sent\n", ntohs (mq->msg->type), ntohs (mq->msg->size));
  GNUNET_free (mq->msg);
  GNUNET_CONTAINER_DLL_remove (ctx->mq_head, ctx->mq_tail, mq);
  GNUNET_free (mq);
  if (NULL != (mq = ctx->mq_head))
  {
    ctx->backoff = GNUNET_TIME_STD_BACKOFF (ctx->backoff);
    ctx->tx =
        GNUNET_CLIENT_notify_transmit_ready (ctx->conn, ntohs (mq->msg->size),
                                             ctx->backoff, GNUNET_NO,
                                             &conn_transmit_ready,
                                             ctx);
  }  
  return wrote;
}


/**
 * Queues a message in send queue assocaited with conn
 *
 * @param msg the message to queue
 */
static void
queue_message (struct ConnCtx *ctx, struct GNUNET_MessageHeader *msg)
{
  struct MessageQueue *mq;
  uint16_t type;
  uint16_t size;

  type = ntohs (msg->type);
  size = ntohs (msg->size);
  mq = GNUNET_malloc (sizeof (struct MessageQueue));
  mq->msg = msg;
  LOG_DEBUG ("Queueing message of type %u, size %u for sending\n", type, size);
  GNUNET_CONTAINER_DLL_insert_tail (ctx->mq_head, ctx->mq_tail, mq);
  if (NULL == ctx->tx)
  {
    ctx->backoff = GNUNET_TIME_STD_BACKOFF (ctx->backoff);
    ctx->tx =
        GNUNET_CLIENT_notify_transmit_ready (ctx->conn, size,
                                             ctx->backoff, GNUNET_NO,
                                             &conn_transmit_ready,
                                             ctx);
  }
}


/**
 * Dispatcher for received messages
 *
 * @param cls connection context
 * @param msg message received, NULL on timeout or fatal error
 */
static void
dispatch (void *cls, const struct GNUNET_MessageHeader *msg);


/**
 * forward stdin data to MSHD
 *
 * @param cls NULL
 * @param tc scheduler task context
 */
static void
fwd_stdin (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{  
  struct MSH_MSG_CmdIO *msg;
  ssize_t size;
  uint16_t msg_size;
  
  task_fwd_stdin = GNUNET_SCHEDULER_NO_TASK;
  if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
  {
    return;
  }
  size = GNUNET_DISK_file_read (fh_stdin, recv_buf,
                                GNUNET_SERVER_MAX_MESSAGE_SIZE
                                - sizeof (struct MSH_MSG_CmdIO));
  if (GNUNET_SYSERR == size)
  {
    GNUNET_break (0);
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  if (0 == size)
  {
    GNUNET_SCHEDULER_shutdown ();
    return;
  }  
  msg_size = sizeof (struct MSH_MSG_CmdIO) + size;
  msg = GNUNET_malloc (msg_size);
  msg->header.size = htons (msg_size);
  msg->header.type = htons (MSH_MTYPE_CMD_STREAM_STDIN);
  (void) memcpy (msg->data, recv_buf, size);
  queue_message (&ctx_remote, &msg->header);
  task_fwd_stdin = 
      GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
                                      fh_stdin, &fwd_stdin, NULL);
}


/**
 * Type of a function to call when we receive a message
 * from the service.
 *
 * @param ctx the connection context
 * @param msg message received, NULL on timeout or fatal error
 * @return GNUNET_OK to keep the connection open; any other value to close it
 */
static int
handle_cmd_output (struct ConnCtx *ctx,
                   const struct GNUNET_MessageHeader *msg_)
{
  const struct MSH_MSG_CmdIO *msg;
  uint16_t size;
  uint16_t mtype;

  msg = (const struct MSH_MSG_CmdIO *) msg_;
  mtype = ntohs (msg->header.type);
  if ( (MSH_MTYPE_CMD_STREAM_STDOUT != mtype)
       && (MSH_MTYPE_CMD_STREAM_STDERR != mtype) )
  {
    GNUNET_break (0);
    GNUNET_SCHEDULER_shutdown ();
    return GNUNET_SYSERR;;
  }
  size = ntohs (msg->header.size);
  size -= sizeof (struct MSH_MSG_CmdIO);
  switch (mtype)
  {
  case MSH_MTYPE_CMD_STREAM_STDOUT:
    GNUNET_break (size ==  GNUNET_DISK_file_write (fh_stdout, msg->data, size));
    break;
  case MSH_MTYPE_CMD_STREAM_STDERR:
    if (NULL == fh_stderr)
      break;
    GNUNET_break (size == GNUNET_DISK_file_write (fh_stderr, msg->data, size));
    break;
  default:
    GNUNET_assert (0);
  }
  return GNUNET_OK;
}


/**
 * Type of a function to call when we receive a message
 * from the service.
 *
 * @param ctx the connection context
 * @param msg message received, NULL on timeout or fatal error
 * @return GNUNET_OK to keep the connection open; any other value to close it
 */
static int
handle_exec_begin (struct ConnCtx *ctx,
                   const struct GNUNET_MessageHeader *msg_)
{
  LOG (GNUNET_ERROR_TYPE_INFO, "Executing remote command\n");
  fh_stdin = GNUNET_DISK_get_handle_from_native (stdin);
  fh_stdout = GNUNET_DISK_get_handle_from_native (stdout);
  fh_stderr = GNUNET_DISK_get_handle_from_native (stderr);
  GNUNET_assert (NULL != fh_stdin);
  GNUNET_assert (NULL != fh_stdout);
  state = STATE_FORWARD_STREAMS;
  task_fwd_stdin = 
      GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
                                      fh_stdin, &fwd_stdin, NULL);
  result = GNUNET_OK;
  return GNUNET_OK;
}


/**
 * Set the terminal into raw mode
 */
void
enter_raw_mode(int quiet)
{
  struct termios raw_tio;

  raw_tio = tio;
  raw_tio.c_iflag |= IGNPAR;
  raw_tio.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
#ifdef IUCLC
  raw_tio.c_iflag &= ~IUCLC;
#endif
  raw_tio.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
#ifdef IEXTEN
  raw_tio.c_lflag &= ~IEXTEN;
#endif
  raw_tio.c_oflag &= ~OPOST;
  raw_tio.c_cc[VMIN] = 1;
  raw_tio.c_cc[VTIME] = 0;
  if (tcsetattr(fileno(stdin), TCSADRAIN, &raw_tio) == -1) {
    if (!quiet)
      GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "tcsetattr");
  } else
    tty_rawed = 1;
}


/**
 * Generate PTY_MODE message containing the settings to be used for the created
 * pseudo-tty
 *
 * @return the PTY_MODE message; NULL upon error
 */
static struct MSH_MSG_PtyMode *
gen_pty_msg ()
{
  struct MSH_MSG_PtyMode *tmsg;
  char *cp;
  uint16_t *ts;
  size_t size;
  unsigned int count;

  cp = getenv ("TERM");  

  /* count the number of terminal settings */
  count = 0;
#define TTYCHAR(NAME,OP)                        \
  count++;
#define TTYMODE(NAME,FIELD,OP)                  \
  count++;
#include "ttymodes.h"
#undef TTYCHAR
#undef TTYMODE

  /* Build the terminal mode message */
  size = sizeof (struct MSH_MSG_PtyMode) + 
      (sizeof (uint16_t) * 2 * count) + ((NULL != cp) ? (strlen(cp) + 1) : 0);
  tmsg = GNUNET_malloc (size);
  tmsg->header.type = htons (MSH_MTYPE_PTY_MODE);
  tmsg->header.size = htons (size);
  tmsg->ws_row = htons (ws.ws_row);
  tmsg->ws_col = htons (ws.ws_col);
  tmsg->ws_xpixel = htons (ws.ws_xpixel);
  tmsg->ws_ypixel = htons (ws.ws_ypixel);
  tmsg->ospeed = htonl (speed_to_baud (cfgetospeed (&tio)));
  tmsg->ispeed = htonl (speed_to_baud (cfgetispeed (&tio)));
  tmsg->nsettings = htons (count);
  /* Populate the message with settings */
  ts = (uint16_t *) &tmsg[1];
#define TTYCHAR(NAME,OP)                        \
    *(ts++) = htons (OP);                       \
    *(ts++) = htons (tio.c_cc[NAME]);

#define TTYMODE(NAME, FIELD, OP)                \
    *(ts++) = htons (OP);                       \
    *(ts++) = htons ((tio.FIELD & NAME) != 0);
#include "ttymodes.h"
#undef TTYCHAR
#undef TTYMODE
  /* copy the TERM env variable's value */
  if (NULL != cp)
    (void) memcpy ((void *)ts, cp, strlen (cp));
  return tmsg;
}


/**
 * Type of a function to call when we receive a message
 * from the service.
 *
 * @param ctx the connection context
 * @param msg message received, NULL on timeout or fatal error
 * @return GNUNET_OK to keep the connection open; any other value to close it
 */
static int
handle_challenge_response (struct ConnCtx *ctx,
                           const struct GNUNET_MessageHeader *msg_)
{
  struct GNUNET_MessageHeader *msg;
  struct MSH_MSG_RunCmd *rmsg;
  struct MSH_MSG_PtyMode *ptymsg;
  uint16_t size;
  
  LOG_DEBUG ("Received CHALLENGE_RESPONSE.  Forwarding it to remote MSHD\n");
  msg = GNUNET_copy_message (msg_);
  queue_message (&ctx_remote, msg);
  destroy_conn_ctx (&ctx_local);
  if (can_pty && !disable_pty)
  {
    ptymsg = gen_pty_msg ();
    queue_message (&ctx_remote, &ptymsg->header);
    enter_raw_mode (1);
  }
  /* now queue RUN_CMD message */
  size = sizeof (struct MSH_MSG_RunCmd) + cmdstr_len;
  rmsg = GNUNET_malloc (size);
  rmsg->header.size = htons (size);
  rmsg->header.type = htons (MSH_MTYPE_RUNCMD);
  (void) memcpy (rmsg->cmd, cmdstr, cmdstr_len);
  queue_message (&ctx_remote, &rmsg->header);
  return GNUNET_OK;
}


/**
 * Type of a function to call when we receive a message
 * from the service.
 *
 * @param ctx the connection context
 * @param msg message received, NULL on timeout or fatal error
 * @return GNUNET_OK to keep the connection open; any other value to close it
 */
static int
handle_challenge (struct ConnCtx *ctx,
                  const struct GNUNET_MessageHeader *msg_)
{
  struct GNUNET_MessageHeader *msg;

  LOG_DEBUG ("Received CHALLENGE message.  Forwarding it to parent MSHD\n");
  if (sizeof (struct MSH_MSG_Challenge) > ntohs (msg_->size))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  msg = GNUNET_copy_message (msg_);
  queue_message (&ctx_local, msg);
  return GNUNET_OK;
}


/**
 * Tries to establish a connection to the target remote MSHD
 */
static void
target_connect ()
{
  struct MSH_MSG_SessionOpen *msg;
  struct GNUNET_CONFIGURATION_Handle *cfg;
  uint16_t size;

  cfg = GNUNET_CONFIGURATION_create ();
  GNUNET_CONFIGURATION_set_value_string (cfg, MSHD_REMOTE, "HOSTNAME",
                                         ip2str (target));
  GNUNET_CONFIGURATION_set_value_number (cfg, MSHD_REMOTE, "PORT",
                                         target_port);
  ctx_remote.cfg = cfg;
  ctx_remote.conn = GNUNET_CLIENT_connect (MSHD_REMOTE, ctx_remote.cfg);
  GNUNET_assert (NULL != ctx_remote.conn);
  size = sizeof (struct MSH_MSG_SessionOpen);
  msg = GNUNET_malloc (size);
  msg->header.size = htons (size);
  msg->header.type = htons (MSH_MTYPE_SESSION_OPEN);
  //(void) memcpy (msg->cmd, cmdstr, cmdstr_len);
  if (can_pty)
    msg->type = htonl (MSH_SESSION_TYPE_INTERACTIVE);
  else
    msg->type = htonl (MSH_SESSION_TYPE_NONINTERACTIVE);
  queue_message (&ctx_remote, &msg->header);
  GNUNET_CLIENT_receive (ctx_remote.conn, &dispatch, &ctx_remote,
                         GNUNET_TIME_UNIT_FOREVER_REL);
 }


/**
 * Type of a function to call when we receive a message
 * from the service.
 *
 * @param ctx the connection context
 * @param msg message received, NULL on timeout or fatal error
 * @return GNUNET_OK to keep the connection open; any other value to close it
 */
static int
handle_lookup_reply (struct ConnCtx *ctx,
                     const struct GNUNET_MessageHeader *msg_)
{
  const struct MSH_MSG_AddressLookupReply *msg;
  uint16_t size;

  size = ntohs (msg_->size);
  msg = (const struct MSH_MSG_AddressLookupReply *) msg_;
  if (0 == (target_port = ntohs (msg->port)))
  {
    if ('\0' != msg->emsg[(size - sizeof (struct MSH_MSG_AddressLookup)) - 1])
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
    LOG_ERROR ("Address lookup for IP:%s failed with error: %s\n",
               ip2str (target), msg->emsg);
    return GNUNET_SYSERR;
  }
  LOG_DEBUG ("ADDRESS_LOOKUP_REPLY:  Service available on %s:%u\n",
             ip2str (target), target_port);
  target_connect ();
  return GNUNET_OK;
}


/**
 * Dispatcher for received messages
 *
 * @param cls connection context
 * @param msg message received, NULL on timeout or fatal error
 */
static void
dispatch (void *cls, const struct GNUNET_MessageHeader *msg)
{
  struct ConnCtx *ctx = cls;
  int ret;
  
  if (NULL == msg)
  {
    LOG_DEBUG ("Broken IPC connection\n");
    goto err_ret;
  }
  switch (ntohs (msg->type))
  {
  case MSH_MTYPE_ADDRESS_LOOKUP_REPLY:
    ret = handle_lookup_reply (ctx, msg);
    break;
  case MSH_MTYPE_CHALLENGE:
    ret = handle_challenge (ctx, msg);
    break;
  case MSH_MTYPE_CHALLENGE_RESPONSE:
    ret = handle_challenge_response (ctx, msg);
    break;
  case MSH_MTYPE_EXEC_BEGIN:
    ret = handle_exec_begin (ctx, msg);
    break;
  case MSH_MTYPE_CMD_STREAM_STDOUT:
  case MSH_MTYPE_CMD_STREAM_STDERR:
    ret = handle_cmd_output (ctx, msg);
    break;
  default:
    LOG (GNUNET_ERROR_TYPE_WARNING, "Unrecognised message of type %u received\n", 
         ntohs (msg->type));
    goto err_ret;
  }
  if (GNUNET_SYSERR == ret)
    goto err_ret;

  /* We destroy local_ctx in handle_challenge_response, hence this check */
  if (NULL != ctx->conn)
    GNUNET_CLIENT_receive (ctx->conn, &dispatch, ctx, GNUNET_TIME_UNIT_FOREVER_REL);
  return;

 err_ret:
  destroy_conn_ctx (ctx);
  GNUNET_SCHEDULER_shutdown ();
}


/**
 * Function called with the result on the service test.
 *
 * @param cls NULL
 * @param status GNUNET_YES if the service is running,
 *               GNUNET_NO if the service is not running
 *               GNUNET_SYSERR if the configuration is invalid
 */
static void
status_cb (void *cls, int status)
{
  struct MSH_MSG_AddressLookup *msg;
  uint16_t size;

  test = NULL;
  if (GNUNET_YES != status)
  {
    LOG_ERROR ("Service not running\n");
    return;
  }
  ctx_local.conn = GNUNET_CLIENT_connect (MSHD_LOCAL, ctx_local.cfg);
  GNUNET_assert (NULL != ctx_local.conn);
  GNUNET_assert (0 != cmdstr_len);
  size = sizeof (struct MSH_MSG_AddressLookup);
  msg = GNUNET_malloc (size);
  msg->header.size = htons (size);
  msg->header.type = htons (MSH_MTYPE_ADDRESS_LOOKUP);
  msg->ip = htonl ((uint32_t) target);
  queue_message (&ctx_local, &msg->header);
  GNUNET_CLIENT_receive (ctx_local.conn, &dispatch, &ctx_local,
                         GNUNET_TIME_UNIT_FOREVER_REL);
  task_shutdown = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
                                                &do_shutdown, NULL);
}


/**
 * Reads terminal settings and window size
 *
 * @return GNUNET_OK upon success; GNUNET_SYSERR upon error
 */
static int
read_tty_settings ()
{
  if (ioctl(0, TIOCGWINSZ, &ws) < 0)
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "ioctl");
    return GNUNET_SYSERR;
  }
  if (-1 == tcgetattr (0, &tio))
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "tcgetattr");
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Main function that will be run.
 *
 * @param cls closure
 * @param args remaining command-line arguments
 * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 * @param cfg_ configuration
 */
static void 
run (void *cls, char *const *args, const char *cfgfile,
     const struct GNUNET_CONFIGURATION_Handle *cfg_)
{
  char *ipstr;
  char *psock_path;
  size_t arg_len;
  unsigned int cnt;
  
  if (!disable_pty && isatty (0))
    can_pty = 1;
  if (need_pty && !can_pty)
  {
    LOG_ERROR ("Not attached to a terminal but pseudo-tty is requested (-t) option");
    return;
  }
  if (can_pty)
  {
    if (GNUNET_OK != read_tty_settings ())
      return;
  }
  state = STATE_DELIVER_CMD;
  if (NULL == (ipstr = args[0]))
  {
    LOG_ERROR ("Require an IP address\n");
    fprintf (stderr, "%s", help_text);
    return; 
  }
  target = inet_network (ipstr);
  if ((uint32_t) -1 == target)
  {
    LOG_ERROR ("Invalid IP address given");
    return;
  }
  for (cnt = 1; NULL != args[cnt]; cnt++)
  {
    arg_len = strlen (args[cnt]) + 1;
    cmdstr = GNUNET_realloc (cmdstr, cmdstr_len + arg_len);
    (void) memcpy (cmdstr + cmdstr_len, args[cnt], arg_len);
    cmdstr_len += arg_len;
  }
  if (0 == cmdstr_len)
  {
    LOG_ERROR ("Require command to execute remotely\n");
    fprintf (stderr, "%s", help_text);
    return;
  }
  if (NULL == (psock_path = getenv("MSHD_SOCK")) )
  {
    LOG_ERROR ("Could not find socket for local MSHD.  Are we running under MSHD?\n");
    return;
  }
  LOG_DEBUG ("Unix socket path: %s\n", psock_path);
  ctx_local.cfg = GNUNET_CONFIGURATION_dup (cfg_);
  GNUNET_CONFIGURATION_set_value_string (ctx_local.cfg, MSHD_LOCAL,
                                         "UNIXPATH", psock_path);
  GNUNET_CONFIGURATION_set_value_string (ctx_local.cfg, "TESTING",
                                        "USE_ABSTRACT_SOCKETS", "YES");
  test = GNUNET_CLIENT_service_test (MSHD_LOCAL, ctx_local.cfg,
                                     GNUNET_TIME_UNIT_SECONDS,
                                     &status_cb, NULL);
}


/**
 * Program entry point
 */
int
main (int argc, char * const argv[])
{
  static const struct GNUNET_GETOPT_CommandLineOption options[] = {
    {'T', "disable-pty", NULL, _("do not allocate a pseudo-tty"), 0,
     &GNUNET_GETOPT_set_one, (void *) &disable_pty},
    {'t', "require-pty", NULL, _("exit with error if a pseudo-tty cannot be allocated"),
     0, &GNUNET_GETOPT_set_one, (void *) &need_pty},
    GNUNET_GETOPT_OPTION_END
  };
   
  result = GNUNET_SYSERR;
  if (GNUNET_OK != GNUNET_PROGRAM_run (argc, argv, "msh",
                                       help_text,
                                       options, &run, NULL))
  {
    GNUNET_break (0);
    return 1;
  }
  return (GNUNET_OK == result) ? 0 : 2;
}