gnunet-service-nat_mini.c

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/*
     This file is part of GNUnet.
     Copyright (C) 2011-2014, 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_nat_service.h"
#include "gnunet-service-nat_mini.h"
#include "nat.h"
 
#define LOG(kind, ...) GNUNET_log_from (kind, "nat", __VA_ARGS__)
 
#define MAP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)
 
#define UNMAP_TIMEOUT \
        GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 1)
 
#define MAP_REFRESH_FREQ \
        GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)
 
 
/* ************************* external-ip calling ************************ */
 
struct GNUNET_NAT_ExternalHandle
{
  GNUNET_NAT_IPCallback cb;
 
  void *cb_cls;
 
  struct GNUNET_SCHEDULER_Task *task;
 
  struct GNUNET_Process *eip;
 
  struct GNUNET_DISK_PipeHandle *opipe;
 
  const struct GNUNET_DISK_FileHandle *r;
 
  size_t off;
 
  char buf[17];
 
  enum GNUNET_NAT_StatusCode ret;
};
 
 
static void
read_external_ipv4 (void *cls)
{
  struct GNUNET_NAT_ExternalHandle *eh = cls;
  ssize_t ret;
  struct in_addr addr;
 
  eh->task = NULL;
  ret = GNUNET_DISK_file_read (eh->r,
                               &eh->buf[eh->off],
                               sizeof(eh->buf) - eh->off);
  if (ret > 0)
  {
    /* try to read more */
    eh->off += ret;
    eh->task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
                                               eh->r,
                                               &read_external_ipv4,
                                               eh);
    return;
  }
  eh->ret = GNUNET_NAT_ERROR_EXTERNAL_IP_UTILITY_OUTPUT_INVALID;
  if ((eh->off > 7) && (eh->buf[eh->off - 1] == '\n'))
  {
    eh->buf[eh->off - 1] = '\0';
    if (1 == inet_pton (AF_INET, eh->buf, &addr))
    {
      if (0 == addr.s_addr)
        eh->ret =
          GNUNET_NAT_ERROR_EXTERNAL_IP_ADDRESS_INVALID;     /* got 0.0.0.0 */
      else
        eh->ret = GNUNET_NAT_ERROR_SUCCESS;
    }
  }
  eh->cb (eh->cb_cls,
          (GNUNET_NAT_ERROR_SUCCESS == eh->ret) ? &addr : NULL,
          eh->ret);
  GNUNET_NAT_mini_get_external_ipv4_cancel_ (eh);
}
 
 
static void
signal_external_ip_error (void *cls)
{
  struct GNUNET_NAT_ExternalHandle *eh = cls;
 
  eh->task = NULL;
  eh->cb (eh->cb_cls, NULL, eh->ret);
  GNUNET_free (eh);
}
 
 
struct GNUNET_NAT_ExternalHandle *
GNUNET_NAT_mini_get_external_ipv4_ (GNUNET_NAT_IPCallback cb, void *cb_cls)
{
  struct GNUNET_NAT_ExternalHandle *eh;
 
  eh = GNUNET_new (struct GNUNET_NAT_ExternalHandle);
  eh->cb = cb;
  eh->cb_cls = cb_cls;
  eh->ret = GNUNET_NAT_ERROR_SUCCESS;
  if (GNUNET_SYSERR ==
      GNUNET_OS_check_helper_binary ("external-ip", GNUNET_NO, NULL))
  {
    LOG (GNUNET_ERROR_TYPE_INFO, _ ("`external-ip' command not found\n"));
    eh->ret = GNUNET_NAT_ERROR_EXTERNAL_IP_UTILITY_NOT_FOUND;
    eh->task = GNUNET_SCHEDULER_add_now (&signal_external_ip_error, eh);
    return eh;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Running `external-ip' to determine our external IP\n");
  eh->opipe = GNUNET_DISK_pipe (GNUNET_DISK_PF_BLOCKING_RW);
  if (NULL == eh->opipe)
  {
    eh->ret = GNUNET_NAT_ERROR_IPC_FAILURE;
    eh->task = GNUNET_SCHEDULER_add_now (&signal_external_ip_error, eh);
    return eh;
  }
  eh->eip = GNUNET_process_create ();
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_process_set_options (
                   eh->eip,
                   GNUNET_process_option_std_inheritance (
                     GNUNET_OS_INHERIT_STD_NONE),
                   GNUNET_process_option_inherit_wpipe (eh->opipe,
                                                        STDOUT_FILENO)));
  if ( (GNUNET_OK !=
        GNUNET_process_set_command (eh->eip,
                                    "external-ip")) ||
       (GNUNET_OK !=
        GNUNET_process_start (eh->eip)) )
  {
    GNUNET_process_destroy (eh->eip);
    eh->eip = NULL;
    GNUNET_DISK_pipe_close (eh->opipe);
    eh->ret = GNUNET_NAT_ERROR_EXTERNAL_IP_UTILITY_FAILED;
    eh->task = GNUNET_SCHEDULER_add_now (&signal_external_ip_error,
                                         eh);
    return eh;
  }
  GNUNET_DISK_pipe_close_end (eh->opipe, GNUNET_DISK_PIPE_END_WRITE);
  eh->r = GNUNET_DISK_pipe_handle (eh->opipe, GNUNET_DISK_PIPE_END_READ);
  eh->task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
                                             eh->r,
                                             &read_external_ipv4,
                                             eh);
  return eh;
}
 
 
void
GNUNET_NAT_mini_get_external_ipv4_cancel_ (struct GNUNET_NAT_ExternalHandle *eh)
{
  if (NULL != eh->eip)
  {
    (void) GNUNET_process_kill (eh->eip,
                                SIGKILL);
    GNUNET_break (GNUNET_OK ==
                  GNUNET_process_wait (eh->eip,
                                       true,
                                       NULL,
                                       NULL));
    GNUNET_process_destroy (eh->eip);
  }
  if (NULL != eh->opipe)
  {
    GNUNET_DISK_pipe_close (eh->opipe);
    eh->opipe = NULL;
  }
  if (NULL != eh->task)
  {
    GNUNET_SCHEDULER_cancel (eh->task);
    eh->task = NULL;
  }
  GNUNET_free (eh);
}
 
 
/* ************************* upnpc calling ************************ */
 
 
struct GNUNET_NAT_MiniHandle
{
  GNUNET_NAT_MiniAddressCallback ac;
 
  void *ac_cls;
 
  struct GNUNET_OS_CommandHandle *map_cmd;
 
  struct GNUNET_OS_CommandHandle *refresh_cmd;
 
  struct GNUNET_OS_CommandHandle *unmap_cmd;
 
  struct sockaddr_in current_addr;
 
  struct GNUNET_SCHEDULER_Task *refresh_task;
 
  int is_tcp;
 
  int did_map;
 
  int found;
 
  uint16_t port;
};
 
 
static void
do_refresh (void *cls);
 
 
static void
process_map_output (void *cls, const char *line);
 
 
static void
run_upnpc_r (struct GNUNET_NAT_MiniHandle *mini)
{
  char pstr[6];
 
  GNUNET_snprintf (pstr, sizeof(pstr), "%u", (unsigned int) mini->port);
  mini->map_cmd = GNUNET_OS_command_run (&process_map_output,
                                         mini,
                                         MAP_TIMEOUT,
                                         "upnpc",
                                         "upnpc",
                                         "-r",
                                         pstr,
                                         mini->is_tcp ? "tcp" : "udp",
                                         NULL);
  if (NULL == mini->map_cmd)
  {
    mini->ac (mini->ac_cls,
              GNUNET_SYSERR,
              NULL,
              0,
              GNUNET_NAT_ERROR_UPNPC_FAILED);
    return;
  }
}
 
 
static void
process_refresh_output (void *cls, const char *line)
{
  struct GNUNET_NAT_MiniHandle *mini = cls;
  char pstr[9];
  const char *s;
  unsigned int nport;
  struct in_addr exip;
 
  if (NULL == line)
  {
    GNUNET_OS_command_stop (mini->refresh_cmd);
    mini->refresh_cmd = NULL;
    if (GNUNET_NO == mini->found)
    {
      /* mapping disappeared, try to re-create */
      if (GNUNET_YES == mini->did_map)
      {
        mini->ac (mini->ac_cls,
                  GNUNET_NO,
                  (const struct sockaddr *) &mini->current_addr,
                  sizeof(mini->current_addr),
                  GNUNET_NAT_ERROR_SUCCESS);
        mini->did_map = GNUNET_NO;
      }
      run_upnpc_r (mini);
    }
    return;
  }
  if (! mini->did_map)
    return; /* never mapped, won't find our mapping anyway */
 
  /* we're looking for output of the form:
  * "ExternalIPAddress = 12.134.41.124" */
 
  s = strstr (line, "ExternalIPAddress = ");
  if (NULL != s)
  {
    s += strlen ("ExternalIPAddress = ");
    if (1 != inet_pton (AF_INET, s, &exip))
      return;   /* skip */
    if (exip.s_addr == mini->current_addr.sin_addr.s_addr)
      return;   /* no change */
    /* update mapping */
    mini->ac (mini->ac_cls,
              GNUNET_NO,
              (const struct sockaddr *) &mini->current_addr,
              sizeof(mini->current_addr),
              GNUNET_NAT_ERROR_SUCCESS);
    mini->current_addr.sin_addr = exip;
    mini->ac (mini->ac_cls,
              GNUNET_YES,
              (const struct sockaddr *) &mini->current_addr,
              sizeof(mini->current_addr),
              GNUNET_NAT_ERROR_SUCCESS);
    return;
  }
  /*
   * we're looking for output of the form:
   *
   * "0 TCP  3000->192.168.2.150:3000  'libminiupnpc' ''"
   * "1 UDP  3001->192.168.2.150:3001  'libminiupnpc' ''"
   *
   * the pattern we look for is:
   *
   * "%s TCP  PORT->STRING:OURPORT *" or
   * "%s UDP  PORT->STRING:OURPORT *"
   */GNUNET_snprintf (pstr, sizeof(pstr), ":%u ", mini->port);
  if (NULL == (s = strstr (line, "->")))
    return; /* skip */
  if (NULL == strstr (s, pstr))
    return; /* skip */
  if (1 != sscanf (line,
                   (mini->is_tcp) ? "%*u TCP  %u->%*s:%*u %*s"
                   : "%*u UDP  %u->%*s:%*u %*s",
                   &nport))
    return; /* skip */
  mini->found = GNUNET_YES;
  if (nport == ntohs (mini->current_addr.sin_port))
    return; /* no change */
 
  /* external port changed, update mapping */
  mini->ac (mini->ac_cls,
            GNUNET_NO,
            (const struct sockaddr *) &mini->current_addr,
            sizeof(mini->current_addr),
            GNUNET_NAT_ERROR_SUCCESS);
  mini->current_addr.sin_port = htons ((uint16_t) nport);
  mini->ac (mini->ac_cls,
            GNUNET_YES,
            (const struct sockaddr *) &mini->current_addr,
            sizeof(mini->current_addr),
            GNUNET_NAT_ERROR_SUCCESS);
}
 
 
static void
do_refresh (void *cls)
{
  struct GNUNET_NAT_MiniHandle *mini = cls;
  int ac;
 
  mini->refresh_task =
    GNUNET_SCHEDULER_add_delayed (MAP_REFRESH_FREQ, &do_refresh, mini);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Running `upnpc' to check if our mapping still exists\n");
  mini->found = GNUNET_NO;
  ac = GNUNET_NO;
  if (NULL != mini->map_cmd)
  {
    /* took way too long, abort it! */
    GNUNET_OS_command_stop (mini->map_cmd);
    mini->map_cmd = NULL;
    ac = GNUNET_YES;
  }
  if (NULL != mini->refresh_cmd)
  {
    /* took way too long, abort it! */
    GNUNET_OS_command_stop (mini->refresh_cmd);
    mini->refresh_cmd = NULL;
    ac = GNUNET_YES;
  }
  mini->refresh_cmd = GNUNET_OS_command_run (&process_refresh_output,
                                             mini,
                                             MAP_TIMEOUT,
                                             "upnpc",
                                             "upnpc",
                                             "-l",
                                             NULL);
  if (GNUNET_YES == ac)
    mini->ac (mini->ac_cls,
              GNUNET_SYSERR,
              NULL,
              0,
              GNUNET_NAT_ERROR_UPNPC_TIMEOUT);
}
 
 
static void
process_map_output (void *cls, const char *line)
{
  struct GNUNET_NAT_MiniHandle *mini = cls;
  const char *ipaddr;
  char *ipa;
  const char *pstr;
  unsigned int port;
 
  if (NULL == line)
  {
    GNUNET_OS_command_stop (mini->map_cmd);
    mini->map_cmd = NULL;
    if (GNUNET_YES != mini->did_map)
      mini->ac (mini->ac_cls,
                GNUNET_SYSERR,
                NULL,
                0,
                GNUNET_NAT_ERROR_UPNPC_PORTMAP_FAILED);
    if (NULL == mini->refresh_task)
      mini->refresh_task =
        GNUNET_SCHEDULER_add_delayed (MAP_REFRESH_FREQ, &do_refresh, mini);
    return;
  }
  /*
   * The upnpc output we're after looks like this:
   *
   * "external 87.123.42.204:3000 TCP is redirected to internal 192.168.2.150:3000"
   */if ((NULL == (ipaddr = strstr (line, " "))) ||
      (NULL == (pstr = strstr (ipaddr, ":"))) ||
      (1 != sscanf (pstr + 1, "%u", &port)))
  {
    return;   /* skip line */
  }
  ipa = GNUNET_strdup (ipaddr + 1);
  strstr (ipa, ":")[0] = '\0';
  if (1 != inet_pton (AF_INET, ipa, &mini->current_addr.sin_addr))
  {
    GNUNET_free (ipa);
    return;   /* skip line */
  }
  GNUNET_free (ipa);
 
  mini->current_addr.sin_port = htons (port);
  mini->current_addr.sin_family = AF_INET;
#if HAVE_SOCKADDR_IN_SIN_LEN
  mini->current_addr.sin_len = sizeof(struct sockaddr_in);
#endif
  mini->did_map = GNUNET_YES;
  mini->ac (mini->ac_cls,
            GNUNET_YES,
            (const struct sockaddr *) &mini->current_addr,
            sizeof(mini->current_addr),
            GNUNET_NAT_ERROR_SUCCESS);
}
 
 
struct GNUNET_NAT_MiniHandle *
GNUNET_NAT_mini_map_start (uint16_t port,
                           int is_tcp,
                           GNUNET_NAT_MiniAddressCallback ac,
                           void *ac_cls)
{
  struct GNUNET_NAT_MiniHandle *ret;
 
  if (GNUNET_SYSERR == GNUNET_OS_check_helper_binary ("upnpc", GNUNET_NO, NULL))
  {
    LOG (GNUNET_ERROR_TYPE_INFO, _ ("`upnpc' command not found\n"));
    ac (ac_cls, GNUNET_SYSERR, NULL, 0, GNUNET_NAT_ERROR_UPNPC_NOT_FOUND);
    return NULL;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Running `upnpc' to install mapping\n");
  ret = GNUNET_new (struct GNUNET_NAT_MiniHandle);
  ret->ac = ac;
  ret->ac_cls = ac_cls;
  ret->is_tcp = is_tcp;
  ret->port = port;
  ret->refresh_task =
    GNUNET_SCHEDULER_add_delayed (MAP_REFRESH_FREQ, &do_refresh, ret);
  run_upnpc_r (ret);
  return ret;
}
 
 
static void
process_unmap_output (void *cls, const char *line)
{
  struct GNUNET_NAT_MiniHandle *mini = cls;
 
  if (NULL == line)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG, "UPnP unmap done\n");
    GNUNET_OS_command_stop (mini->unmap_cmd);
    mini->unmap_cmd = NULL;
    GNUNET_free (mini);
    return;
  }
  /* we don't really care about the output... */
}
 
 
void
GNUNET_NAT_mini_map_stop (struct GNUNET_NAT_MiniHandle *mini)
{
  char pstr[6];
 
  if (NULL != mini->refresh_task)
  {
    GNUNET_SCHEDULER_cancel (mini->refresh_task);
    mini->refresh_task = NULL;
  }
  if (NULL != mini->refresh_cmd)
  {
    GNUNET_OS_command_stop (mini->refresh_cmd);
    mini->refresh_cmd = NULL;
  }
  if (NULL != mini->map_cmd)
  {
    GNUNET_OS_command_stop (mini->map_cmd);
    mini->map_cmd = NULL;
  }
  if (GNUNET_NO == mini->did_map)
  {
    GNUNET_free (mini);
    return;
  }
  mini->ac (mini->ac_cls,
            GNUNET_NO,
            (const struct sockaddr *) &mini->current_addr,
            sizeof(mini->current_addr),
            GNUNET_NAT_ERROR_SUCCESS);
  /* Note: oddly enough, deletion uses the external port whereas
   * addition uses the internal port; this rarely matters since they
   * often are the same, but it might... */
  GNUNET_snprintf (pstr,
                   sizeof(pstr),
                   "%u",
                   (unsigned int) ntohs (mini->current_addr.sin_port));
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Unmapping port %u with UPnP\n",
       ntohs (mini->current_addr.sin_port));
  mini->unmap_cmd = GNUNET_OS_command_run (&process_unmap_output,
                                           mini,
                                           UNMAP_TIMEOUT,
                                           "upnpc",
                                           "upnpc",
                                           "-d",
                                           pstr,
                                           mini->is_tcp ? "tcp" : "udp",
                                           NULL);
}
 
 
/* end of gnunet-service-nat_mini.c */