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
29 #include "gnunet_disk_lib.h"
30 #include "gnunet_getopt_lib.h"
31 #include "gnunet_protocols.h"
32 #include "gnunet_service_lib.h"
33 #include "gnunet_statistics_service.h"
34 #include "gnunet_strings_lib.h"
35 #include "gnunet_time_lib.h"
39 * A cached DNS lookup result.
44 * This is a linked list.
49 * Hostname in human-readable form.
54 * Hostname in binary format.
59 * Last time this entry was updated.
61 struct GNUNET_TIME_Absolute last_refresh;
64 * Last time this entry was requested.
66 struct GNUNET_TIME_Absolute last_request;
69 * Number of bytes in sa.
76 * Start of the linked list of cached DNS lookup results.
78 static struct IPCache *head;
83 * Resolve the given request using getnameinfo
85 * @param cache the request to resolve (and where to store the result)
88 getnameinfo_resolve (struct IPCache *cache)
92 if (0 == getnameinfo (cache->sa,
94 hostname, sizeof (hostname), NULL, 0, 0))
95 cache->addr = GNUNET_strdup (hostname);
100 #if HAVE_GETHOSTBYADDR
102 * Resolve the given request using gethostbyaddr
104 * @param cache the request to resolve (and where to store the result)
107 gethostbyaddr_resolve (struct IPCache *cache)
111 switch (cache->sa->sa_family)
114 ent = gethostbyaddr (&((struct sockaddr_in *) cache->sa)->sin_addr,
115 sizeof (struct in_addr), AF_INET);
118 ent = gethostbyaddr (&((struct sockaddr_in6 *) cache->sa)->sin6_addr,
119 sizeof (struct in6_addr), AF_INET6);
125 cache->addr = GNUNET_strdup (ent->h_name);
130 * Resolve the given request using the available methods.
132 * @param cache the request to resolve (and where to store the result)
135 cache_resolve (struct IPCache *cache)
138 if (cache->addr == NULL)
139 getnameinfo_resolve (cache);
141 #if HAVE_GETHOSTBYADDR
142 if (cache->addr == NULL)
143 gethostbyaddr_resolve (cache);
150 * Get an IP address as a string (works for both IPv4 and IPv6). Note
151 * that the resolution happens asynchronously and that the first call
152 * may not immediately result in the FQN (but instead in a
153 * human-readable IP address).
155 * @param client handle to the client making the request (for sending the reply)
156 * @param sa should be of type "struct sockaddr*"
157 * @param salen number of bytes in sa
160 get_ip_as_string (struct GNUNET_SERVER_Client *client,
161 const struct sockaddr *sa, socklen_t salen)
163 struct IPCache *cache;
164 struct IPCache *prev;
165 struct GNUNET_TIME_Absolute now;
166 struct GNUNET_SERVER_TransmitContext *tc;
168 if (salen < sizeof (struct sockaddr))
171 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
174 now = GNUNET_TIME_absolute_get ();
177 while ((cache != NULL) &&
178 ((cache->salen != salen) || (0 != memcmp (cache->sa, sa, salen))))
180 if (GNUNET_TIME_absolute_get_duration (cache->last_request).rel_value <
185 prev->next = cache->next;
186 GNUNET_free_non_null (cache->addr);
187 GNUNET_free (cache->sa);
194 GNUNET_free_non_null (cache->addr);
195 GNUNET_free (cache->sa);
206 cache->last_request = now;
207 if (GNUNET_TIME_absolute_get_duration (cache->last_request).rel_value <
210 GNUNET_free_non_null (cache->addr);
213 cache_resolve (cache);
218 cache = GNUNET_malloc (sizeof (struct IPCache));
220 cache->salen = salen;
221 cache->sa = GNUNET_malloc (salen);
222 memcpy (cache->sa, sa, salen);
223 cache->last_request = GNUNET_TIME_absolute_get ();
224 cache->last_refresh = GNUNET_TIME_absolute_get ();
226 cache_resolve (cache);
229 tc = GNUNET_SERVER_transmit_context_create (client);
230 if (cache->addr != NULL)
231 GNUNET_SERVER_transmit_context_append_data (tc,
233 strlen (cache->addr) + 1,
234 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
235 GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
236 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
237 GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
243 getaddrinfo_resolve (struct GNUNET_SERVER_TransmitContext *tc,
244 const char *hostname, int domain)
247 struct addrinfo hints;
248 struct addrinfo *result;
249 struct addrinfo *pos;
251 memset (&hints, 0, sizeof (struct addrinfo));
254 hints.ai_family = domain;
256 hints.ai_family = AF_INET;
258 hints.ai_socktype = SOCK_STREAM; /* go for TCP */
260 if (0 != (s = getaddrinfo (hostname, NULL, &hints, &result)))
262 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
263 _("Could not resolve `%s' (%s): %s\n"), hostname,
265 AF_INET) ? "IPv4" : ((domain ==
266 AF_INET6) ? "IPv6" : "any"),
268 if ((s == EAI_BADFLAGS) || (s == EAI_MEMORY)
276 return GNUNET_NO; /* other function may still succeed */
277 return GNUNET_SYSERR;
280 return GNUNET_SYSERR;
284 GNUNET_SERVER_transmit_context_append_data (tc,
287 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
290 freeaddrinfo (result);
295 #if HAVE_GETHOSTBYNAME2
297 gethostbyname2_resolve (struct GNUNET_SERVER_TransmitContext *tc,
298 const char *hostname, int domain)
301 struct sockaddr_in a4;
302 struct sockaddr_in6 a6;
306 if (domain == AF_UNSPEC)
308 ret1 = gethostbyname2_resolve (tc, hostname, AF_INET);
309 ret2 = gethostbyname2_resolve (tc, hostname, AF_INET6);
310 if ((ret1 == GNUNET_OK) || (ret2 == GNUNET_OK))
312 if ((ret1 == GNUNET_SYSERR) || (ret2 == GNUNET_SYSERR))
313 return GNUNET_SYSERR;
316 hp = gethostbyname2 (hostname, domain);
319 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
320 _("Could not find IP of host `%s': %s\n"),
321 hostname, hstrerror (h_errno));
322 return GNUNET_SYSERR;
324 GNUNET_assert (hp->h_addrtype == domain);
325 if (domain == AF_INET)
327 GNUNET_assert (hp->h_length == sizeof (struct in_addr));
328 memset (&a4, 0, sizeof (a4));
329 a4.sin_family = AF_INET;
330 memcpy (&a4.sin_addr, hp->h_addr_list[0], hp->h_length);
331 GNUNET_SERVER_transmit_context_append_data (tc,
334 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
338 GNUNET_assert (hp->h_length == sizeof (struct in6_addr));
339 memset (&a6, 0, sizeof (a6));
340 a6.sin6_family = AF_INET6;
341 memcpy (&a6.sin6_addr, hp->h_addr_list[0], hp->h_length);
342 GNUNET_SERVER_transmit_context_append_data (tc,
345 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
351 #if HAVE_GETHOSTBYNAME
353 gethostbyname_resolve (struct GNUNET_SERVER_TransmitContext *tc,
354 const char *hostname)
357 struct sockaddr_in addr;
359 hp = GETHOSTBYNAME (hostname);
362 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
363 _("Could not find IP of host `%s': %s\n"),
364 hostname, hstrerror (h_errno));
365 return GNUNET_SYSERR;
367 if (hp->h_addrtype != AF_INET)
370 return GNUNET_SYSERR;
372 GNUNET_assert (hp->h_length == sizeof (struct in_addr));
373 memset (&addr, 0, sizeof (addr));
374 addr.sin_family = AF_INET;
375 memcpy (&addr.sin_addr, hp->h_addr_list[0], hp->h_length);
376 GNUNET_SERVER_transmit_context_append_data (tc,
379 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
386 * Convert a string to an IP address.
388 * @param client where to send the IP address
389 * @param hostname the hostname to resolve
390 * @param domain AF_INET or AF_INET6; use AF_UNSPEC for "any"
393 get_ip_from_hostname (struct GNUNET_SERVER_Client *client,
394 const char *hostname, int domain)
397 struct GNUNET_SERVER_TransmitContext *tc;
399 tc = GNUNET_SERVER_transmit_context_create (client);
402 if (ret == GNUNET_NO)
403 ret = getaddrinfo_resolve (tc, hostname, domain);
405 #if HAVE_GETHOSTBYNAME2
406 if (ret == GNUNET_NO)
407 ret = gethostbyname2_resolve (tc, hostname, domain);
409 #if HAVE_GETHOSTBYNAME
410 if ((ret == GNUNET_NO) && ((domain == AF_UNSPEC) || (domain == PF_INET)))
411 gethostbyname_resolve (tc, hostname);
413 GNUNET_SERVER_transmit_context_append_data (tc, NULL, 0,
414 GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
415 GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
420 * Handle GET-message.
423 * @param client identification of the client
424 * @param message the actual message
427 handle_get (void *cls,
428 struct GNUNET_SERVER_Client *client,
429 const struct GNUNET_MessageHeader *message)
432 const struct GNUNET_RESOLVER_GetMessage *msg;
433 const char *hostname;
438 msize = ntohs (message->size);
439 if (msize < sizeof (struct GNUNET_RESOLVER_GetMessage))
442 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
445 msg = (const struct GNUNET_RESOLVER_GetMessage *) message;
446 size = msize - sizeof (struct GNUNET_RESOLVER_GetMessage);
447 direction = ntohl (msg->direction);
448 domain = ntohl (msg->domain);
449 if (direction == GNUNET_NO)
451 /* IP from hostname */
452 hostname = (const char *) &msg[1];
453 if (hostname[size - 1] != '\0')
456 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
460 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
461 _("Resolver asked to look up `%s'.\n"), hostname);
463 get_ip_from_hostname (client, hostname, domain);
468 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
469 _("Resolver asked to look up IP address.\n"));
471 get_ip_as_string (client, (const struct sockaddr *) &msg[1], size);
477 * Process resolver requests.
480 * @param server the initialized server
481 * @param cfg configuration to use
485 struct GNUNET_SERVER_Handle *server,
486 const struct GNUNET_CONFIGURATION_Handle *cfg)
488 static const struct GNUNET_SERVER_MessageHandler handlers[] = {
489 {&handle_get, NULL, GNUNET_MESSAGE_TYPE_RESOLVER_REQUEST, 0},
492 GNUNET_SERVER_add_handlers (server, handlers);
497 * The main function for the resolver service.
499 * @param argc number of arguments from the command line
500 * @param argv command line arguments
501 * @return 0 ok, 1 on error
504 main (int argc, char *const *argv)
510 GNUNET_SERVICE_run (argc,
512 "resolver", GNUNET_SERVICE_OPTION_NONE,
513 &run, NULL)) ? 0 : 1;
518 GNUNET_free_non_null (head->addr);
519 GNUNET_free (head->sa);
526 /* end of gnunet-service-resolver.c */