aboutsummaryrefslogtreecommitdiff
path: root/src/nat/gnunet-service-nat_externalip.c
blob: 0a251bdb299ffc83a35ec2ce5d9e4d9ca35eb583 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
/*
     This file is part of GNUnet.
     Copyright (C) 2009, 2015, 2016, 2017 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
 */
/**
 * Code to figure out what our external IPv4 address(es) might
 * be (external IPv4s are what is seen on the rest of the Internet).
 *
 * This can be implemented using different methods, and we allow
 * the main service to be notified about changes to what we believe
 * is our external IPv4 address.
 *
 * Note that this is explicitly only about NATed systems; if one
 * of our network interfaces has a global IP address this does
 * not count as "external".
 *
 * @file nat/gnunet-service-nat_externalip.c
 * @brief Functions for monitoring external IPv4 addresses
 * @author Christian Grothoff
 */
#include "platform.h"
#include <math.h>
#include "gnunet_util_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_signatures.h"
#include "gnunet_statistics_service.h"
#include "gnunet_resolver_service.h"
#include "gnunet_nat_service.h"
#include "gnunet-service-nat.h"
#include "gnunet-service-nat_externalip.h"
#include "gnunet-service-nat_stun.h"
#include "gnunet-service-nat_mini.h"
#include "gnunet-service-nat_helper.h"
#include "nat.h"
#include <gcrypt.h>


/**
 * How long do we wait until we re-try running `external-ip` if the
 * command failed to terminate nicely?
 */
#define EXTERN_IP_RETRY_TIMEOUT GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_MINUTES, 15)

/**
 * How long do we wait until we re-try running `external-ip` if the
 * command failed (but terminated)?
 */
#define EXTERN_IP_RETRY_FAILURE GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_MINUTES, 30)

/**
 * How long do we wait until we re-try running `external-ip` if the
 * command succeeded?
 */
#define EXTERN_IP_RETRY_SUCCESS GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_MINUTES, 5)


/**
 * Handle to monitor for external IP changes.
 */
struct GN_ExternalIPMonitor
{
  /**
   * Kept in DLL.
   */
  struct GN_ExternalIPMonitor *next;

  /**
   * Kept in DLL.
   */
  struct GN_ExternalIPMonitor *prev;

  /**
   * Function to call when we believe our external IPv4 address changed.
   */
  GN_NotifyExternalIPv4Change cb;

  /**
   * Closure for @e cb.
   */
  void *cb_cls;
};


/**
 * List of monitors, kept in DLL.
 */
static struct GN_ExternalIPMonitor *mon_head;

/**
 * List of monitors, kept in DLL.
 */
static struct GN_ExternalIPMonitor *mon_tail;

/**
 * Task run to obtain our external IP (if #enable_upnp is set
 * and if we find we have a NATed IP address).
 */
static struct GNUNET_SCHEDULER_Task *probe_external_ip_task;

/**
 * Handle to our operation to run `external-ip`.
 */
static struct GNUNET_NAT_ExternalHandle *probe_external_ip_op;

/**
 * What is our external IP address as claimed by `external-ip`?
 * 0 for unknown.
 */
static struct in_addr mini_external_ipv4;


/**
 * Tell relevant clients about a change in our external
 * IPv4 address.
 *
 * @param add #GNUNET_YES to add, #GNUNET_NO to remove
 * @param v4 the external address that changed
 */
static void
notify_monitors_external_ipv4_change (int add,
                                      const struct in_addr *v4)
{
  for (struct GN_ExternalIPMonitor *mon = mon_head;
       NULL != mon;
       mon = mon->next)
    mon->cb (mon->cb_cls,
             v4,
             add);
}


/**
 * Task used to run `external-ip` to get our external IPv4
 * address and pass it to NATed clients if possible.
 *
 * @param cls NULL
 */
static void
run_external_ip (void *cls);


/**
 * We learn our current external IP address.  If it changed,
 * notify all of our applicable clients. Also re-schedule
 * #run_external_ip with an appropriate timeout.
 *
 * @param cls NULL
 * @param addr the address, NULL on errors
 * @param result #GNUNET_NAT_ERROR_SUCCESS on success, otherwise the specific error code
 */
static void
handle_external_ip (void *cls,
                    const struct in_addr *addr,
                    enum GNUNET_NAT_StatusCode result)
{
  char buf[INET_ADDRSTRLEN];

  probe_external_ip_op = NULL;
  GNUNET_SCHEDULER_cancel (probe_external_ip_task);
  probe_external_ip_task
    = GNUNET_SCHEDULER_add_delayed ((NULL == addr)
                                    ? EXTERN_IP_RETRY_FAILURE
                                    : EXTERN_IP_RETRY_SUCCESS,
                                    &run_external_ip,
                                    NULL);
  switch (result)
  {
  case GNUNET_NAT_ERROR_SUCCESS:
    GNUNET_assert (NULL != addr);
    if (addr->s_addr == mini_external_ipv4.s_addr)
      return;   /* not change */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Our external IP is now %s\n",
                inet_ntop (AF_INET,
                           addr,
                           buf,
                           sizeof(buf)));
    if (0 != mini_external_ipv4.s_addr)
      notify_monitors_external_ipv4_change (GNUNET_NO,
                                            &mini_external_ipv4);
    mini_external_ipv4 = *addr;
    notify_monitors_external_ipv4_change (GNUNET_YES,
                                          &mini_external_ipv4);
    break;

  default:
    if (0 != mini_external_ipv4.s_addr)
      notify_monitors_external_ipv4_change (GNUNET_NO,
                                            &mini_external_ipv4);
    mini_external_ipv4.s_addr = 0;
    break;
  }
}


/**
 * Task used to run `external-ip` to get our external IPv4
 * address and pass it to NATed clients if possible.
 *
 * @param cls NULL
 */
static void
run_external_ip (void *cls)
{
  probe_external_ip_task
    = GNUNET_SCHEDULER_add_delayed (EXTERN_IP_RETRY_TIMEOUT,
                                    &run_external_ip,
                                    NULL);
  if (NULL != probe_external_ip_op)
  {
    GNUNET_NAT_mini_get_external_ipv4_cancel_ (probe_external_ip_op);
    probe_external_ip_op = NULL;
  }
  probe_external_ip_op
    = GNUNET_NAT_mini_get_external_ipv4_ (&handle_external_ip,
                                          NULL);
}


/**
 * We have changed our opinion about being NATed in the first
 * place. Adapt our probing.
 *
 * @param have_nat #GNUNET_YES if we believe we are behind NAT
 */
void
GN_nat_status_changed (int have_nat)
{
  if (GNUNET_YES != enable_upnp)
    return;
  if ((GNUNET_YES == have_nat) &&
      (NULL == probe_external_ip_task) &&
      (NULL == probe_external_ip_op))
  {
    probe_external_ip_task
      = GNUNET_SCHEDULER_add_now (&run_external_ip,
                                  NULL);
    return;
  }
  if (GNUNET_NO == have_nat)
  {
    if (NULL != probe_external_ip_task)
    {
      GNUNET_SCHEDULER_cancel (probe_external_ip_task);
      probe_external_ip_task = NULL;
    }
    if (NULL != probe_external_ip_op)
    {
      GNUNET_NAT_mini_get_external_ipv4_cancel_ (probe_external_ip_op);
      probe_external_ip_op = NULL;
    }
  }
}


/**
 * Start monitoring external IPv4 addresses.
 *
 * @param cb function to call on changes
 * @param cb_cls closure for @a cb
 * @return handle to cancel
 */
struct GN_ExternalIPMonitor *
GN_external_ipv4_monitor_start (GN_NotifyExternalIPv4Change cb,
                                void *cb_cls)
{
  struct GN_ExternalIPMonitor *mon;

  mon = GNUNET_new (struct GN_ExternalIPMonitor);
  mon->cb = cb;
  mon->cb_cls = cb_cls;
  GNUNET_CONTAINER_DLL_insert (mon_head,
                               mon_tail,
                               mon);
  if (0 != mini_external_ipv4.s_addr)
    cb (cb_cls,
        &mini_external_ipv4,
        GNUNET_YES);
  return mon;
}


/**
 * Stop calling monitor.
 *
 * @param mon monitor to call
 */
void
GN_external_ipv4_monitor_stop (struct GN_ExternalIPMonitor *mon)
{
  GNUNET_CONTAINER_DLL_remove (mon_head,
                               mon_tail,
                               mon);
  GNUNET_free (mon);
}

/* end of gnunet-service-nat_externalip.c */