aboutsummaryrefslogtreecommitdiff
path: root/src/util/gnunet-service-resolver.c
blob: ec56292a8cadac2895cca394dad02e238d1dcde0 (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
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
/*
     This file is part of GNUnet.
     Copyright (C) 2007-2013 Christian Grothoff (and other contributing authors)

     GNUnet 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, 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
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file util/gnunet-service-resolver.c
 * @brief code to do DNS resolution
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_statistics_service.h"
#include "resolver.h"

/**
 * A cached DNS lookup result (for reverse lookup).
 */
struct IPCache
{
  /**
   * This is a doubly linked list.
   */
  struct IPCache *next;

  /**
   * This is a doubly linked list.
   */
  struct IPCache *prev;

  /**
   * Hostname in human-readable form.
   */
  char *addr;

  /**
   * Binary IP address, allocated at the end of this struct.
   */
  const void *ip;

  /**
   * Last time this entry was updated.
   */
  struct GNUNET_TIME_Absolute last_refresh;

  /**
   * Last time this entry was requested.
   */
  struct GNUNET_TIME_Absolute last_request;

  /**
   * Number of bytes in ip.
   */
  size_t ip_len;

  /**
   * Address family of the IP.
   */
  int af;
};


/**
 * Start of the linked list of cached DNS lookup results.
 */
static struct IPCache *cache_head;

/**
 * Tail of the linked list of cached DNS lookup results.
 */
static struct IPCache *cache_tail;


#if HAVE_GETNAMEINFO
/**
 * Resolve the given request using getnameinfo
 *
 * @param cache the request to resolve (and where to store the result)
 */
static void
getnameinfo_resolve (struct IPCache *cache)
{
  char hostname[256];
  const struct sockaddr *sa;
  struct sockaddr_in v4;
  struct sockaddr_in6 v6;
  size_t salen;
  int ret;

  switch (cache->af)
  {
  case AF_INET:
    GNUNET_assert (cache->ip_len == sizeof (struct in_addr));
    sa = (const struct sockaddr*) &v4;
    memset (&v4, 0, sizeof (v4));
    v4.sin_addr = * (const struct in_addr*) cache->ip;
    v4.sin_family = AF_INET;
#if HAVE_SOCKADDR_IN_SIN_LEN
    v4.sin_len = sizeof (v4);
#endif
    salen = sizeof (v4);
    break;
  case AF_INET6:
    GNUNET_assert (cache->ip_len == sizeof (struct in6_addr));
    sa = (const struct sockaddr*) &v6;
    memset (&v6, 0, sizeof (v6));
    v6.sin6_addr = * (const struct in6_addr*) cache->ip;
    v6.sin6_family = AF_INET6;
#if HAVE_SOCKADDR_IN_SIN_LEN
    v6.sin6_len = sizeof (v6);
#endif
    salen = sizeof (v6);
    break;
  default:
    GNUNET_assert (0);
  }

  if (0 ==
      (ret = getnameinfo (sa, salen,
                          hostname, sizeof (hostname),
                          NULL,
                          0, 0)))
  {
    cache->addr = GNUNET_strdup (hostname);
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "getnameinfo failed: %s\n",
                gai_strerror (ret));
  }
}
#endif


#if HAVE_GETHOSTBYADDR
/**
 * Resolve the given request using gethostbyaddr
 *
 * @param cache the request to resolve (and where to store the result)
 */
static void
gethostbyaddr_resolve (struct IPCache *cache)
{
  struct hostent *ent;

  ent = gethostbyaddr (cache->ip,
		       cache->ip_len,
		       cache->af);
  if (NULL != ent)
  {
    cache->addr = GNUNET_strdup (ent->h_name);
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "gethostbyaddr failed: %s\n",
                hstrerror (h_errno));
  }
}
#endif


/**
 * Resolve the given request using the available methods.
 *
 * @param cache the request to resolve (and where to store the result)
 */
static void
cache_resolve (struct IPCache *cache)
{
#if HAVE_GETNAMEINFO
  if (NULL == cache->addr)
    getnameinfo_resolve (cache);
#endif
#if HAVE_GETHOSTBYADDR
  if (NULL == cache->addr)
    gethostbyaddr_resolve (cache);
#endif
}


/**
 * Get an IP address as a string (works for both IPv4 and IPv6).  Note
 * that the resolution happens asynchronously and that the first call
 * may not immediately result in the FQN (but instead in a
 * human-readable IP address).
 *
 * @param client handle to the client making the request (for sending the reply)
 * @param af AF_INET or AF_INET6
 * @param ip `struct in_addr` or `struct in6_addr`
 */
static void
get_ip_as_string (struct GNUNET_SERVER_Client *client,
                  int af,
		  const void *ip)
{
  struct IPCache *pos;
  struct IPCache *next;
  struct GNUNET_TIME_Absolute now;
  struct GNUNET_SERVER_TransmitContext *tc;
  size_t ip_len;
  struct in6_addr ix;

  switch (af)
  {
  case AF_INET:
    ip_len = sizeof (struct in_addr);
    break;
  case AF_INET6:
    ip_len = sizeof (struct in6_addr);
    break;
  default:
    GNUNET_assert (0);
  }
  now = GNUNET_TIME_absolute_get ();
  next = cache_head;
  while ( (NULL != (pos = next)) &&
	  ( (pos->af != af) ||
	    (pos->ip_len != ip_len) ||
	    (0 != memcmp (pos->ip, ip, ip_len))) )
  {
    next = pos->next;
    if (GNUNET_TIME_absolute_get_duration (pos->last_request).rel_value_us <
        60 * 60 * 1000 * 1000LL)
    {
      GNUNET_CONTAINER_DLL_remove (cache_head,
				   cache_tail,
				   pos);
      GNUNET_free_non_null (pos->addr);
      GNUNET_free (pos);
      continue;
    }
  }
  if (NULL != pos)
  {
    if ( (1 == inet_pton (af,
                          pos->ip,
                          &ix)) &&
         (GNUNET_TIME_absolute_get_duration (pos->last_request).rel_value_us >
          120 * 1000 * 1000LL) )
    {
      /* try again if still numeric AND 2 minutes have expired */
      GNUNET_free_non_null (pos->addr);
      pos->addr = NULL;
      cache_resolve (pos);
      pos->last_request = now;
    }
  }
  else
  {
    pos = GNUNET_malloc (sizeof (struct IPCache) + ip_len);
    pos->ip = &pos[1];
    memcpy (&pos[1], ip, ip_len);
    pos->last_request = now;
    pos->last_refresh = now;
    pos->ip_len = ip_len;
    pos->af = af;
    GNUNET_CONTAINER_DLL_insert (cache_head,
				 cache_tail,
				 pos);
    cache_resolve (pos);
  }
  tc = GNUNET_SERVER_transmit_context_create (client);
  if (NULL != pos->addr)
    GNUNET_SERVER_transmit_context_append_data (tc, pos->addr,
                                                strlen (pos->addr) + 1,
                                                GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
  else
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Reverse lookup failed\n");
  GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
                                              GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
}


#if HAVE_GETADDRINFO
static int
getaddrinfo_resolve (struct GNUNET_SERVER_TransmitContext *tc,
                     const char *hostname, int af)
{
  int s;
  struct addrinfo hints;
  struct addrinfo *result;
  struct addrinfo *pos;

#ifdef WINDOWS
  /* Due to a bug, getaddrinfo will not return a mix of different families */
  if (AF_UNSPEC == af)
  {
    int ret1;
    int ret2;
    ret1 = getaddrinfo_resolve (tc, hostname, AF_INET);
    ret2 = getaddrinfo_resolve (tc, hostname, AF_INET6);
    if ((ret1 == GNUNET_OK) || (ret2 == GNUNET_OK))
      return GNUNET_OK;
    if ((ret1 == GNUNET_SYSERR) || (ret2 == GNUNET_SYSERR))
      return GNUNET_SYSERR;
    return GNUNET_NO;
  }
#endif

  memset (&hints, 0, sizeof (struct addrinfo));
  hints.ai_family = af;
  hints.ai_socktype = SOCK_STREAM;      /* go for TCP */

  if (0 != (s = getaddrinfo (hostname, NULL, &hints, &result)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("Could not resolve `%s' (%s): %s\n"),
                hostname,
                (af ==
                 AF_INET) ? "IPv4" : ((af == AF_INET6) ? "IPv6" : "any"),
                gai_strerror (s));
    if ((s == EAI_BADFLAGS) || (s == EAI_MEMORY)
#ifndef WINDOWS
        || (s == EAI_SYSTEM)
#else
        || 1
#endif
        )
      return GNUNET_NO;         /* other function may still succeed */
    return GNUNET_SYSERR;
  }
  if (NULL == result)
    return GNUNET_SYSERR;
  for (pos = result; pos != NULL; pos = pos->ai_next)
  {
    switch (pos->ai_family)
    {
    case AF_INET:
      GNUNET_SERVER_transmit_context_append_data (tc,
						  &((struct sockaddr_in*) pos->ai_addr)->sin_addr,
						  sizeof (struct in_addr),
						  GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
      break;
    case AF_INET6:
      GNUNET_SERVER_transmit_context_append_data (tc,
						  &((struct sockaddr_in6*) pos->ai_addr)->sin6_addr,
						  sizeof (struct in6_addr),
						  GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
      break;
    default:
      /* unsupported, skip */
      break;
    }
  }
  freeaddrinfo (result);
  return GNUNET_OK;
}
#endif


#if HAVE_GETHOSTBYNAME2
static int
gethostbyname2_resolve (struct GNUNET_SERVER_TransmitContext *tc,
                        const char *hostname,
                        int af)
{
  struct hostent *hp;
  int ret1;
  int ret2;

#ifdef WINDOWS
  /* gethostbyname2() in plibc is a compat dummy that calls gethostbyname(). */
  return GNUNET_NO;
#endif

  if (af == AF_UNSPEC)
  {
    ret1 = gethostbyname2_resolve (tc, hostname, AF_INET);
    ret2 = gethostbyname2_resolve (tc, hostname, AF_INET6);
    if ((ret1 == GNUNET_OK) || (ret2 == GNUNET_OK))
      return GNUNET_OK;
    if ((ret1 == GNUNET_SYSERR) || (ret2 == GNUNET_SYSERR))
      return GNUNET_SYSERR;
    return GNUNET_NO;
  }
  hp = gethostbyname2 (hostname, af);
  if (hp == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("Could not find IP of host `%s': %s\n"), hostname,
                hstrerror (h_errno));
    return GNUNET_SYSERR;
  }
  GNUNET_assert (hp->h_addrtype == af);
  switch (af)
  {
  case AF_INET:
    GNUNET_assert (hp->h_length == sizeof (struct in_addr));
    GNUNET_SERVER_transmit_context_append_data (tc,
						hp->h_addr_list[0],
						hp->h_length,
                                                GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
    break;
  case AF_INET6:
    GNUNET_assert (hp->h_length == sizeof (struct in6_addr));
    GNUNET_SERVER_transmit_context_append_data (tc,
						hp->h_addr_list[0],
						hp->h_length,
                                                GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
    break;
  default:
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}
#endif


#if HAVE_GETHOSTBYNAME
static int
gethostbyname_resolve (struct GNUNET_SERVER_TransmitContext *tc,
                       const char *hostname)
{
  struct hostent *hp;

  hp = GETHOSTBYNAME (hostname);
  if (NULL == hp)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("Could not find IP of host `%s': %s\n"),
                hostname,
                hstrerror (h_errno));
    return GNUNET_SYSERR;
  }
  if (hp->h_addrtype != AF_INET)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  GNUNET_assert (hp->h_length == sizeof (struct in_addr));
  GNUNET_SERVER_transmit_context_append_data (tc,
					      hp->h_addr_list[0],
					      hp->h_length,
                                              GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
  return GNUNET_OK;
}
#endif


/**
 * Convert a string to an IP address.
 *
 * @param client where to send the IP address
 * @param hostname the hostname to resolve
 * @param af AF_INET or AF_INET6; use AF_UNSPEC for "any"
 */
static void
get_ip_from_hostname (struct GNUNET_SERVER_Client *client,
                      const char *hostname,
                      int af)
{
  int ret;
  struct GNUNET_SERVER_TransmitContext *tc;

  tc = GNUNET_SERVER_transmit_context_create (client);
  ret = GNUNET_NO;
#if HAVE_GETADDRINFO
  if (ret == GNUNET_NO)
    ret = getaddrinfo_resolve (tc, hostname, af);
#endif
#if HAVE_GETHOSTBYNAME2
  if (ret == GNUNET_NO)
    ret = gethostbyname2_resolve (tc, hostname, af);
#endif
#if HAVE_GETHOSTBYNAME
  if ((ret == GNUNET_NO) && ((af == AF_UNSPEC) || (af == PF_INET)))
    gethostbyname_resolve (tc, hostname);
#endif
  GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
                                              GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
}


/**
 * Handle GET-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_get (void *cls,
            struct GNUNET_SERVER_Client *client,
            const struct GNUNET_MessageHeader *message)
{
  uint16_t msize;
  const struct GNUNET_RESOLVER_GetMessage *msg;
  const void *ip;
  uint16_t size;
  int direction;
  int af;

  msize = ntohs (message->size);
  if (msize < sizeof (struct GNUNET_RESOLVER_GetMessage))
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client,
                                GNUNET_SYSERR);
    return;
  }
  msg = (const struct GNUNET_RESOLVER_GetMessage *) message;
  size = msize - sizeof (struct GNUNET_RESOLVER_GetMessage);
  direction = ntohl (msg->direction);
  af = ntohl (msg->af);
  if (GNUNET_NO == direction)
  {
    /* IP from hostname */
    const char *hostname;

    hostname = (const char *) &msg[1];
    if (hostname[size - 1] != '\0')
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client,
                                  GNUNET_SYSERR);
      return;
    }
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Resolver asked to look up `%s'.\n",
                hostname);
    get_ip_from_hostname (client, hostname, af);
    return;
  }
  ip = &msg[1];
  switch (af)
  {
  case AF_INET:
    if (size != sizeof (struct in_addr))
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client,
                                  GNUNET_SYSERR);
      return;
    }
    break;
  case AF_INET6:
    if (size != sizeof (struct in6_addr))
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client,
                                  GNUNET_SYSERR);
      return;
    }
    break;
  default:
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client,
                                GNUNET_SYSERR);
    return;
  }
  {
    char buf[INET6_ADDRSTRLEN];

    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		"Resolver asked to look up IP address `%s'.\n",
		inet_ntop (af, ip, buf, sizeof (buf)));
  }
  get_ip_as_string (client, af, ip);
}


/**
 * Process resolver requests.
 *
 * @param cls closure
 * @param server the initialized server
 * @param cfg configuration to use
 */
static void
run (void *cls, struct GNUNET_SERVER_Handle *server,
     const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  static const struct GNUNET_SERVER_MessageHandler handlers[] = {
    {&handle_get, NULL, GNUNET_MESSAGE_TYPE_RESOLVER_REQUEST, 0},
    {NULL, NULL, 0, 0}
  };
  GNUNET_SERVER_add_handlers (server, handlers);
}


/**
 * The main function for the resolver service.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *const *argv)
{
  struct IPCache *pos;
  int ret;

  ret =
      (GNUNET_OK ==
       GNUNET_SERVICE_run (argc, argv,
                           "resolver",
                           GNUNET_SERVICE_OPTION_NONE,
                           &run, NULL)) ? 0 : 1;
  while (NULL != (pos = cache_head))
  {
    GNUNET_CONTAINER_DLL_remove (cache_head,
				 cache_tail,
				 pos);
    GNUNET_free_non_null (pos->addr);
    GNUNET_free (pos);
  }
  return ret;
}

#if defined(LINUX) && defined(__GLIBC__)
#include <malloc.h>

/**
 * MINIMIZE heap size (way below 128k) since this process doesn't need much.
 */
void __attribute__ ((constructor))
GNUNET_ARM_memory_init ()
{
  mallopt (M_TRIM_THRESHOLD, 4 * 1024);
  mallopt (M_TOP_PAD, 1 * 1024);
  malloc_trim (0);
}
#endif


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