nat_api_stun.c

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/*
     This file is part of GNUnet.
     Copyright (C) 2009, 2015, 2016 GNUnet e.V.
 
     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.
 
     GNUnet 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
     Affero General Public License for more details.
 
     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
     SPDX-License-Identifier: AGPL3.0-or-later
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_resolver_service.h"
#include "gnunet_nat_service.h"
 
 
#include "nat_stun.h"
 
#define LOG(kind, ...) GNUNET_log_from (kind, "stun", __VA_ARGS__)
 
#define TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)
 
 
struct GNUNET_NAT_STUN_Handle
{
  struct GNUNET_RESOLVER_RequestHandle *dns_active;
 
  struct GNUNET_NETWORK_Handle *sock;
 
  char *stun_server;
 
  GNUNET_NAT_TestCallback cb;
 
  void *cb_cls;
 
  int dns_success;
 
  uint16_t stun_port;
};
 
 
static int
encode_message (enum StunClasses msg_class,
                enum StunMethods method)
{
  return ((msg_class & 1) << 4) | ((msg_class & 2) << 7)
         | (method & 0x000f) | ((method & 0x0070) << 1) | ((method & 0x0f800)
                                                           << 2);
}
 
 
static void
generate_request_id (struct stun_header *req)
{
  req->magic = htonl (STUN_MAGIC_COOKIE);
  for (unsigned int x = 0; x < 3; x++)
    req->id.id[x] = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
                                              UINT32_MAX);
}
 
 
static void
stun_dns_callback (void *cls,
                   const struct sockaddr *addr,
                   socklen_t addrlen)
{
  struct GNUNET_NAT_STUN_Handle *rh = cls;
  struct stun_header req;
  struct sockaddr_in server;
 
  if (NULL == addr)
  {
    rh->dns_active = NULL;
    if (GNUNET_NO == rh->dns_success)
    {
      LOG (GNUNET_ERROR_TYPE_INFO,
           "Error resolving host %s\n",
           rh->stun_server);
      rh->cb (rh->cb_cls,
              GNUNET_NAT_ERROR_NOT_ONLINE);
    }
    else if (GNUNET_SYSERR == rh->dns_success)
    {
      rh->cb (rh->cb_cls,
              GNUNET_NAT_ERROR_INTERNAL_NETWORK_ERROR);
    }
    else
    {
      rh->cb (rh->cb_cls,
              GNUNET_NAT_ERROR_SUCCESS);
    }
    GNUNET_NAT_stun_make_request_cancel (rh);
    return;
  }
 
  rh->dns_success = GNUNET_YES;
  memset (&server, 0, sizeof(server));
  server.sin_family = AF_INET;
  server.sin_addr = ((struct sockaddr_in *) addr)->sin_addr;
  server.sin_port = htons (rh->stun_port);
#if HAVE_SOCKADDR_IN_SIN_LEN
  server.sin_len = (u_char) sizeof(struct sockaddr_in);
#endif
 
  /* Craft the simplest possible STUN packet. A request binding */
  generate_request_id (&req);
  req.msglen = htons (0);
  req.msgtype = htons (encode_message (STUN_REQUEST,
                                       STUN_BINDING));
 
  /* Send the packet */
  if (-1 ==
      GNUNET_NETWORK_socket_sendto (rh->sock,
                                    &req,
                                    sizeof(req),
                                    (const struct sockaddr *) &server,
                                    sizeof(server)))
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
                         "sendto");
    rh->dns_success = GNUNET_SYSERR;
    return;
  }
}
 
 
struct GNUNET_NAT_STUN_Handle *
GNUNET_NAT_stun_make_request (const char *server,
                              uint16_t port,
                              struct GNUNET_NETWORK_Handle *sock,
                              GNUNET_NAT_TestCallback cb,
                              void *cb_cls)
{
  struct GNUNET_NAT_STUN_Handle *rh;
 
  rh = GNUNET_new (struct GNUNET_NAT_STUN_Handle);
  rh->sock = sock;
  rh->cb = cb;
  rh->cb_cls = cb_cls;
  rh->stun_server = GNUNET_strdup (server);
  rh->stun_port = port;
  rh->dns_success = GNUNET_NO;
  rh->dns_active = GNUNET_RESOLVER_ip_get (rh->stun_server,
                                           AF_INET,
                                           TIMEOUT,
                                           &stun_dns_callback,
                                           rh);
  if (NULL == rh->dns_active)
  {
    GNUNET_NAT_stun_make_request_cancel (rh);
    return NULL;
  }
  return rh;
}
 
 
void
GNUNET_NAT_stun_make_request_cancel (struct GNUNET_NAT_STUN_Handle *rh)
{
  if (NULL != rh->dns_active)
  {
    GNUNET_RESOLVER_request_cancel (rh->dns_active);
    rh->dns_active = NULL;
  }
  GNUNET_free (rh->stun_server);
  GNUNET_free (rh);
}
 
 
/* end of nat_stun.c */