inetutils/talk/look_up.c

/*
  Copyright (C) 1995-2025 Free Software Foundation, Inc.

  This file is part of GNU Inetutils.

  GNU Inetutils 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 3 of the License, or (at
  your option) any later version.

  GNU Inetutils 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/'. */

/*
 * Copyright (c) 1983, 1993
 *	The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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 <config.h>

#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <protocols/talkd.h>
#include <unistd.h>
#include <errno.h>
#include "talk_ctl.h"
#include "talk.h"

/*
 * Look for an invitation on 'machine'
 */
static int
look_for_invite (CTL_RESPONSE *rp)
{
  current_state = "Checking for invitation on caller's machine";
  ctl_transact (his_machine_addr, msg, LOOK_UP, rp);
  /* the switch is for later options, such as multiple invitations */
  switch (rp->answer)
    {

    case SUCCESS:
      msg.id_num = htonl (rp->id_num);
      return (1);

    default:
      /* there wasn't an invitation waiting for us */
      return (0);
    }
}

/*
 * See if the local daemon has an invitation for us.
 */
int
check_local (void)
{
  CTL_RESPONSE response;
  CTL_RESPONSE *rp = &response;

  /* the rest of msg was set up in get_names */
  msg.ctl_addr.sa_family = htons (ctl_addr.sin_family);
  memcpy (msg.ctl_addr.sa_data,
	  ((struct sockaddr *) &ctl_addr)->sa_data,
	  sizeof ((struct sockaddr *) & ctl_addr)->sa_data);

  /* must be initiating a talk */
  if (!look_for_invite (rp))
    return (0);
  /*
   * There was an invitation waiting for us,
   * so connect with the other (hopefully waiting) party
   */
  current_state = "Waiting to connect with caller";
  do
    {
      struct sockaddr addr;

      if (rp->addr.sa_family != AF_INET)
	p_error ("Response uses invalid network address");
      errno = 0;
      addr.sa_family = rp->addr.sa_family;
#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
      addr.sa_len = sizeof (struct sockaddr_in);
#endif
      memcpy (&addr.sa_data, &rp->addr.sa_data, sizeof (addr.sa_data));

      if (connect (sockt, &addr, sizeof (addr)) != -1)
	return (1);
    }
  while (errno == EINTR);
  if (errno == ECONNREFUSED)
    {
      /*
       * The caller gave up, but his invitation somehow
       * was not cleared. Clear it and initiate an
       * invitation. (We know there are no newer invitations,
       * the talkd works LIFO.)
       */
      ctl_transact (his_machine_addr, msg, DELETE, rp);
      close (sockt);
      open_sockt ();
      return (0);
    }
  p_error ("Unable to connect with initiator");

  return -1;
}