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_OS_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_YES, GNUNET_YES, GNUNET_NO, GNUNET_YES);
  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_OS_start_process(GNUNET_NO,
                                    0,
                                    NULL,
                                    eh->opipe,
                                    NULL,
                                    "external-ip",
                                    "external-ip",
                                    NULL);
  if (NULL == eh->eip)
    {
      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_OS_process_kill(eh->eip, SIGKILL);
      GNUNET_break(GNUNET_OK == GNUNET_OS_process_wait(eh->eip));
      GNUNET_OS_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 */