2 This file is part of GNUnet.
3 (C) 2007, 2008, 2009 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 2, or (at your
8 option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file util/gnunet-service-resolver.c
23 * @brief code to do DNS resolution
24 * @author Christian Grothoff
27 #include "gnunet_disk_lib.h"
28 #include "gnunet_getopt_lib.h"
29 #include "gnunet_protocols.h"
30 #include "gnunet_service_lib.h"
31 #include "gnunet_statistics_service.h"
32 #include "gnunet_strings_lib.h"
33 #include "gnunet_time_lib.h"
37 * A cached DNS lookup result.
42 * This is a linked list.
47 * Hostname in human-readable form.
52 * Hostname in binary format.
57 * Last time this entry was updated.
59 struct GNUNET_TIME_Absolute last_refresh;
62 * Last time this entry was requested.
64 struct GNUNET_TIME_Absolute last_request;
67 * Number of bytes in sa.
74 * Start of the linked list of cached DNS lookup results.
76 static struct IPCache *head;
81 * Resolve the given request using getnameinfo
83 * @param cache the request to resolve (and where to store the result)
86 getnameinfo_resolve (struct IPCache *cache)
90 if (0 == getnameinfo (cache->sa,
92 hostname, sizeof (hostname), NULL, 0, 0))
93 cache->addr = GNUNET_strdup (hostname);
98 #if HAVE_GETHOSTBYADDR
100 * Resolve the given request using gethostbyaddr
102 * @param cache the request to resolve (and where to store the result)
105 gethostbyaddr_resolve (struct IPCache *cache)
109 switch (cache->sa->sa_family)
112 ent = gethostbyaddr (&((struct sockaddr_in *) cache->sa)->sin_addr,
113 sizeof (struct in_addr), AF_INET);
116 ent = gethostbyaddr (&((struct sockaddr_in6 *) cache->sa)->sin6_addr,
117 sizeof (struct in6_addr), AF_INET6);
123 cache->addr = GNUNET_strdup (ent->h_name);
128 * Resolve the given request using the available methods.
130 * @param cache the request to resolve (and where to store the result)
133 cache_resolve (struct IPCache *cache)
136 if (cache->addr == NULL)
137 getnameinfo_resolve (cache);
139 #if HAVE_GETHOSTBYADDR
140 if (cache->addr == NULL)
141 gethostbyaddr_resolve (cache);
148 * Get an IP address as a string (works for both IPv4 and IPv6). Note
149 * that the resolution happens asynchronously and that the first call
150 * may not immediately result in the FQN (but instead in a
151 * human-readable IP address).
153 * @param client handle to the client making the request (for sending the reply)
154 * @param sa should be of type "struct sockaddr*"
155 * @param salen number of bytes in sa
158 get_ip_as_string (struct GNUNET_SERVER_Client *client,
159 const struct sockaddr *sa, socklen_t salen)
161 struct IPCache *cache;
162 struct IPCache *prev;
163 struct GNUNET_TIME_Absolute now;
164 struct GNUNET_SERVER_TransmitContext *tc;
166 if (salen < sizeof (struct sockaddr))
169 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
172 now = GNUNET_TIME_absolute_get ();
175 while ((cache != NULL) &&
176 ((cache->salen != salen) || (0 != memcmp (cache->sa, sa, salen))))
178 if (GNUNET_TIME_absolute_get_duration (cache->last_request).rel_value <
183 prev->next = cache->next;
184 GNUNET_free_non_null (cache->addr);
185 GNUNET_free (cache->sa);
192 GNUNET_free_non_null (cache->addr);
193 GNUNET_free (cache->sa);
204 cache->last_request = now;
205 if (GNUNET_TIME_absolute_get_duration (cache->last_request).rel_value <
208 GNUNET_free_non_null (cache->addr);
211 cache_resolve (cache);
216 cache = GNUNET_malloc (sizeof (struct IPCache));
218 cache->salen = salen;
219 cache->sa = GNUNET_malloc (salen);
220 memcpy (cache->sa, sa, salen);
221 cache->last_request = GNUNET_TIME_absolute_get ();
222 cache->last_refresh = GNUNET_TIME_absolute_get ();
224 cache_resolve (cache);
227 tc = GNUNET_SERVER_transmit_context_create (client);
228 if (cache->addr != NULL)
229 GNUNET_SERVER_transmit_context_append_data (tc,
231 strlen (cache->addr) + 1,
232 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
233 GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
234 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
235 GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
241 getaddrinfo_resolve (struct GNUNET_SERVER_TransmitContext *tc,
242 const char *hostname, int domain)
245 struct addrinfo hints;
246 struct addrinfo *result;
247 struct addrinfo *pos;
249 memset (&hints, 0, sizeof (struct addrinfo));
252 hints.ai_family = domain;
254 hints.ai_family = AF_INET;
256 hints.ai_socktype = SOCK_STREAM; /* go for TCP */
258 if (0 != (s = getaddrinfo (hostname, NULL, &hints, &result)))
260 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
261 _("Could not resolve `%s' (%s): %s\n"), hostname,
263 AF_INET) ? "IPv4" : ((domain ==
264 AF_INET6) ? "IPv6" : "any"),
266 if ((s == EAI_BADFLAGS) || (s == EAI_MEMORY)
274 return GNUNET_NO; /* other function may still succeed */
275 return GNUNET_SYSERR;
278 return GNUNET_SYSERR;
282 GNUNET_SERVER_transmit_context_append_data (tc,
285 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
288 freeaddrinfo (result);
293 #if HAVE_GETHOSTBYNAME2
295 gethostbyname2_resolve (struct GNUNET_SERVER_TransmitContext *tc,
296 const char *hostname, int domain)
299 struct sockaddr_in a4;
300 struct sockaddr_in6 a6;
304 if (domain == AF_UNSPEC)
306 ret1 = gethostbyname2_resolve (tc, hostname, AF_INET);
307 ret2 = gethostbyname2_resolve (tc, hostname, AF_INET6);
308 if ((ret1 == GNUNET_OK) || (ret2 == GNUNET_OK))
310 if ((ret1 == GNUNET_SYSERR) || (ret2 == GNUNET_SYSERR))
311 return GNUNET_SYSERR;
314 hp = gethostbyname2 (hostname, domain);
317 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
318 _("Could not find IP of host `%s': %s\n"),
319 hostname, hstrerror (h_errno));
320 return GNUNET_SYSERR;
322 GNUNET_assert (hp->h_addrtype == domain);
323 if (domain == AF_INET)
325 GNUNET_assert (hp->h_length == sizeof (struct in_addr));
326 memset (&a4, 0, sizeof (a4));
327 a4.sin_family = AF_INET;
328 #if HAVE_SOCKADDR_IN_SIN_LEN
329 a4.sin_len = (u_char) sizeof (struct sockaddr_in);
331 memcpy (&a4.sin_addr, hp->h_addr_list[0], hp->h_length);
332 GNUNET_SERVER_transmit_context_append_data (tc,
335 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
339 GNUNET_assert (hp->h_length == sizeof (struct in6_addr));
340 memset (&a6, 0, sizeof (a6));
341 a6.sin6_family = AF_INET6;
342 #if HAVE_SOCKADDR_IN_SIN_LEN
343 a6.sin6_len = (u_char) sizeof (struct sockaddr_in6);
345 memcpy (&a6.sin6_addr, hp->h_addr_list[0], hp->h_length);
346 GNUNET_SERVER_transmit_context_append_data (tc,
349 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
355 #if HAVE_GETHOSTBYNAME
357 gethostbyname_resolve (struct GNUNET_SERVER_TransmitContext *tc,
358 const char *hostname)
361 struct sockaddr_in addr;
363 hp = GETHOSTBYNAME (hostname);
366 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
367 _("Could not find IP of host `%s': %s\n"),
368 hostname, hstrerror (h_errno));
369 return GNUNET_SYSERR;
371 if (hp->h_addrtype != AF_INET)
374 return GNUNET_SYSERR;
376 GNUNET_assert (hp->h_length == sizeof (struct in_addr));
377 memset (&addr, 0, sizeof (addr));
378 addr.sin_family = AF_INET;
379 #if HAVE_SOCKADDR_IN_SIN_LEN
380 addr.sin_len = (u_char) sizeof (struct sockaddr_in);
382 memcpy (&addr.sin_addr, hp->h_addr_list[0], hp->h_length);
383 GNUNET_SERVER_transmit_context_append_data (tc,
386 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
393 * Convert a string to an IP address.
395 * @param client where to send the IP address
396 * @param hostname the hostname to resolve
397 * @param domain AF_INET or AF_INET6; use AF_UNSPEC for "any"
400 get_ip_from_hostname (struct GNUNET_SERVER_Client *client,
401 const char *hostname, int domain)
404 struct GNUNET_SERVER_TransmitContext *tc;
406 tc = GNUNET_SERVER_transmit_context_create (client);
409 if (ret == GNUNET_NO)
410 ret = getaddrinfo_resolve (tc, hostname, domain);
412 #if HAVE_GETHOSTBYNAME2
413 if (ret == GNUNET_NO)
414 ret = gethostbyname2_resolve (tc, hostname, domain);
416 #if HAVE_GETHOSTBYNAME
417 if ((ret == GNUNET_NO) && ((domain == AF_UNSPEC) || (domain == PF_INET)))
418 gethostbyname_resolve (tc, hostname);
420 GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
421 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
422 GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
427 * Handle GET-message.
430 * @param client identification of the client
431 * @param message the actual message
434 handle_get (void *cls,
435 struct GNUNET_SERVER_Client *client,
436 const struct GNUNET_MessageHeader *message)
439 const struct GNUNET_RESOLVER_GetMessage *msg;
440 const char *hostname;
441 const struct sockaddr *sa;
446 msize = ntohs (message->size);
447 if (msize < sizeof (struct GNUNET_RESOLVER_GetMessage))
450 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
453 msg = (const struct GNUNET_RESOLVER_GetMessage *) message;
454 size = msize - sizeof (struct GNUNET_RESOLVER_GetMessage);
455 direction = ntohl (msg->direction);
456 domain = ntohl (msg->domain);
457 if (direction == GNUNET_NO)
459 /* IP from hostname */
460 hostname = (const char *) &msg[1];
461 if (hostname[size - 1] != '\0')
464 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
468 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
469 _("Resolver asked to look up `%s'.\n"), hostname);
471 get_ip_from_hostname (client, hostname, domain);
476 char buf[INET6_ADDRSTRLEN];
478 sa = (const struct sockaddr*) &msg[1];
479 if (size < sizeof (struct sockaddr_in))
482 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
485 switch (sa->sa_family)
488 if (size != sizeof (struct sockaddr_in))
491 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
495 inet_ntop (AF_INET, sa, buf, size);
499 if (size != sizeof (struct sockaddr_in6))
502 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
506 inet_ntop (AF_INET6, sa, buf, size);
511 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
515 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
516 _("Resolver asked to look up IP address `%s'.\n"),
519 get_ip_as_string (client, sa, size);
525 * Process resolver requests.
528 * @param server the initialized server
529 * @param cfg configuration to use
533 struct GNUNET_SERVER_Handle *server,
534 const struct GNUNET_CONFIGURATION_Handle *cfg)
536 static const struct GNUNET_SERVER_MessageHandler handlers[] = {
537 {&handle_get, NULL, GNUNET_MESSAGE_TYPE_RESOLVER_REQUEST, 0},
540 GNUNET_SERVER_add_handlers (server, handlers);
545 * The main function for the resolver service.
547 * @param argc number of arguments from the command line
548 * @param argv command line arguments
549 * @return 0 ok, 1 on error
552 main (int argc, char *const *argv)
558 GNUNET_SERVICE_run (argc,
560 "resolver", GNUNET_SERVICE_OPTION_NONE,
561 &run, NULL)) ? 0 : 1;
566 GNUNET_free_non_null (head->addr);
567 GNUNET_free (head->sa);
574 /* end of gnunet-service-resolver.c */