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3 (C) 2009-2013 Christian Grothoff (and other contributing authors)
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13 General Public License for more details.
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21 * @file gns/gnunet-service-gns_interceptor.c
22 * @brief GNUnet GNS interceptor logic
23 * @author Martin Schanzenbach
26 #include "gnunet_util_lib.h"
27 #include "gnunet_dns_service.h"
28 #include "gnunet_dnsparser_lib.h"
29 #include "gnunet-service-gns_resolver.h"
30 #include "gnunet-service-gns_interceptor.h"
35 * Handle to a DNS intercepted
38 struct InterceptLookupHandle
42 * We keep these in a DLL.
44 struct InterceptLookupHandle *next;
47 * We keep these in a DLL.
49 struct InterceptLookupHandle *prev;
52 * the request handle to reply to
54 struct GNUNET_DNS_RequestHandle *request_handle;
57 * the dns parser packet received
59 struct GNUNET_DNSPARSER_Packet *packet;
62 * Handle for the lookup operation.
64 struct GNS_ResolverHandle *lookup;
70 * Our handle to the DNS handler library
72 static struct GNUNET_DNS_Handle *dns_handle;
75 * Key of the zone we start lookups in.
77 static struct GNUNET_CRYPTO_EccPublicKey zone;
82 static struct InterceptLookupHandle *ilh_head;
87 static struct InterceptLookupHandle *ilh_tail;
91 * Reply to dns request with the result from our lookup.
93 * @param cls the closure to the request (an InterceptLookupHandle)
94 * @param rd_count the number of records to return
95 * @param rd the record data
98 reply_to_dns (void *cls, uint32_t rd_count,
99 const struct GNUNET_NAMESTORE_RecordData *rd)
101 struct InterceptLookupHandle *ilh = cls;
102 struct GNUNET_DNSPARSER_Packet *packet = ilh->packet;
103 struct GNUNET_DNSPARSER_Query *query = &packet->queries[0];
108 unsigned int num_answers;
110 /* Put records in the DNS packet */
112 for (i=0; i < rd_count; i++)
113 if (rd[i].record_type == query->type)
117 struct GNUNET_DNSPARSER_Record answer_records[num_answers];
118 struct GNUNET_DNSPARSER_Record additional_records[rd_count - num_answers];
120 packet->answers = answer_records;
121 packet->additional_records = additional_records;
123 for (i=0; i < rd_count; i++)
125 if (rd[i].record_type == query->type)
127 answer_records[i].name = query->name;
128 answer_records[i].type = rd[i].record_type;
129 switch(rd[i].record_type)
131 case GNUNET_DNSPARSER_TYPE_NS:
132 case GNUNET_DNSPARSER_TYPE_CNAME:
133 case GNUNET_DNSPARSER_TYPE_PTR:
134 answer_records[i].data.hostname = (char*)rd[i].data;
136 case GNUNET_DNSPARSER_TYPE_SOA:
137 answer_records[i].data.soa =
138 (struct GNUNET_DNSPARSER_SoaRecord *)rd[i].data;
140 case GNUNET_DNSPARSER_TYPE_MX:
141 answer_records[i].data.mx =
142 (struct GNUNET_DNSPARSER_MxRecord *)rd[i].data;
145 answer_records[i].data.raw.data_len = rd[i].data_size;
146 answer_records[i].data.raw.data = (char*)rd[i].data;
149 GNUNET_break (0 == (rd[i].flags & GNUNET_NAMESTORE_RF_RELATIVE_EXPIRATION));
150 answer_records[i].expiration_time.abs_value_us = rd[i].expiration_time;
151 answer_records[i].class = GNUNET_DNSPARSER_CLASS_INTERNET;
155 additional_records[i].name = query->name;
156 additional_records[i].type = rd[i].record_type;
157 switch(rd[i].record_type)
159 case GNUNET_DNSPARSER_TYPE_NS:
160 case GNUNET_DNSPARSER_TYPE_CNAME:
161 case GNUNET_DNSPARSER_TYPE_PTR:
162 additional_records[i].data.hostname = (char*)rd[i].data;
164 case GNUNET_DNSPARSER_TYPE_SOA:
165 additional_records[i].data.soa =
166 (struct GNUNET_DNSPARSER_SoaRecord *)rd[i].data;
168 case GNUNET_DNSPARSER_TYPE_MX:
169 additional_records[i].data.mx =
170 (struct GNUNET_DNSPARSER_MxRecord *)rd[i].data;
173 additional_records[i].data.raw.data_len = rd[i].data_size;
174 additional_records[i].data.raw.data = (char*)rd[i].data;
177 GNUNET_break (0 == (rd[i].flags & GNUNET_NAMESTORE_RF_RELATIVE_EXPIRATION));
178 additional_records[i].expiration_time.abs_value_us = rd[i].expiration_time;
179 additional_records[i].class = GNUNET_DNSPARSER_CLASS_INTERNET;
182 packet->num_answers = num_answers;
183 packet->num_additional_records = rd_count - num_answers;
184 packet->flags.authoritative_answer = 1;
186 packet->flags.return_code = GNUNET_DNSPARSER_RETURN_CODE_NAME_ERROR;
188 packet->flags.return_code = GNUNET_DNSPARSER_RETURN_CODE_NO_ERROR;
189 packet->flags.query_or_response = 1;
190 ret = GNUNET_DNSPARSER_pack (packet,
191 1024, /* maximum allowed size for DNS reply */
194 if (GNUNET_OK != ret)
196 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
197 _("Error converting GNS response to DNS response!\n"));
201 GNUNET_DNS_request_answer (ilh->request_handle,
206 packet->num_answers = 0;
207 packet->answers = NULL;
208 packet->num_additional_records = 0;
209 packet->additional_records = NULL;
210 GNUNET_DNSPARSER_free_packet (packet);
212 GNUNET_CONTAINER_DLL_remove (ilh_head, ilh_tail, ilh);
218 * The DNS request handler. Called for every incoming DNS request.
220 * @param cls closure, unused
221 * @param rh request handle to user for reply
222 * @param request_length number of bytes in @a request
223 * @param request UDP payload of the DNS request
226 handle_dns_request (void *cls,
227 struct GNUNET_DNS_RequestHandle *rh,
228 size_t request_length,
231 struct GNUNET_DNSPARSER_Packet *p;
232 struct InterceptLookupHandle *ilh;
234 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
235 "Hijacked a DNS request. Processing.\n");
236 if (NULL == (p = GNUNET_DNSPARSER_parse (request, request_length)))
238 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
239 "Received malformed DNS packet, leaving it untouched.\n");
240 GNUNET_DNS_request_forward (rh);
241 GNUNET_DNSPARSER_free_packet (p);
245 /* Check TLD and decide if we or legacy dns is responsible */
246 if (1 != p->num_queries)
248 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
249 "Not exactly one query in DNS packet. Forwarding untouched.\n");
250 GNUNET_DNS_request_forward (rh);
251 GNUNET_DNSPARSER_free_packet(p);
255 /* Check for GNS TLDs. */
256 if ( (GNUNET_YES == is_gads_tld (p->queries[0].name)) ||
257 (GNUNET_YES == is_zkey_tld (p->queries[0].name)) ||
258 (0 == strcmp (p->queries[0].name, GNUNET_GNS_TLD)) )
260 /* Start resolution in GNS */
261 ilh = GNUNET_new (struct InterceptLookupHandle);
262 GNUNET_CONTAINER_DLL_insert (ilh_head, ilh_tail, ilh);
264 ilh->request_handle = rh;
265 ilh->lookup = GNS_resolver_lookup (&zone,
268 NULL /* FIXME: enable shorten for DNS intercepts? */,
273 /* This request does not concern us. Forward to real DNS. */
274 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
275 "Request for `%s' is forwarded to DNS untouched.\n",
277 GNUNET_DNS_request_forward (rh);
278 GNUNET_DNSPARSER_free_packet (p);
283 * Initialized the interceptor
285 * @param gnu_zone the zone to work in
286 * @param c the configuration
287 * @return GNUNET_OK on success
290 GNS_interceptor_init (const struct GNUNET_CRYPTO_EccPublicKey *gnu_zone,
291 const struct GNUNET_CONFIGURATION_Handle *c)
293 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
294 "DNS hijacking enabled. Connecting to DNS service.\n");
296 dns_handle = GNUNET_DNS_connect (c,
297 GNUNET_DNS_FLAG_PRE_RESOLUTION,
300 if (NULL == dns_handle)
302 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
303 _("Failed to connect to the DNS service!\n"));
304 return GNUNET_SYSERR;
311 * Disconnect from interceptor
314 GNS_interceptor_done ()
316 struct InterceptLookupHandle *ilh;
318 while (NULL != (ilh = ilh_head))
320 GNUNET_CONTAINER_DLL_remove (ilh_head, ilh_tail, ilh);
321 GNS_resolver_lookup_cancel (ilh->lookup);
322 GNUNET_DNS_request_drop (ilh->request_handle);
323 GNUNET_DNSPARSER_free_packet (ilh->packet);
326 if (NULL != dns_handle)
328 GNUNET_DNS_disconnect (dns_handle);
333 /* end of gnunet-service-gns_interceptor.c */