src/vpn/gnunet-service-dns.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2009 Christian Grothoff (and other contributing authors)
   4
   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 3, or (at your
   8      option) any later version.
   9
  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.
  14
  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.
  19 */
  20
  21 /**
  22  * @file vpn/gnunet-service-dns.c
  23  * @author Philipp Toelke
  24  */
  25 #include "platform.h"
  26 #include "gnunet_getopt_lib.h"
  27 #include "gnunet_service_lib.h"
  28 #include "gnunet_network_lib.h"
  29 #include "gnunet_os_lib.h"
  30 #include "gnunet-service-dns-p.h"
  31 #include "gnunet_protocols.h"
  32 #include "gnunet-vpn-packet.h"
  33 #include "gnunet-vpn-pretty-print.h"
  34 #include "gnunet_container_lib.h"
  35 #include "gnunet-dns-parser.h"
  36 #include "gnunet_dht_service.h"
  37 #include "gnunet_block_lib.h"
  38 #include "block_dns.h"
  39 #include "gnunet_crypto_lib.h"
  40 #include "gnunet_signatures.h"
  41
  42 struct dns_cls {
  43         struct GNUNET_SCHEDULER_Handle *sched;
  44
  45         struct GNUNET_NETWORK_Handle *dnsout;
  46
  47         struct GNUNET_DHT_Handle *dht;
  48
  49         unsigned short dnsoutport;
  50
  51         const struct GNUNET_CONFIGURATION_Handle *cfg;
  52
  53         struct answer_packet_list *head;
  54         struct answer_packet_list *tail;
  55 };
  56 static struct dns_cls mycls;
  57
  58 struct dns_query_id_state {
  59         unsigned valid:1;
  60         struct GNUNET_SERVER_Client* client;
  61         unsigned local_ip:32;
  62         unsigned remote_ip:32;
  63         unsigned local_port:16;
  64         char* name;
  65         unsigned namelen:8;
  66 };
  67 static struct dns_query_id_state query_states[65536]; /* This is < 1.5MiB */
  68
  69 void hijack(unsigned short port) {
  70         char port_s[6];
  71
  72         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Hijacking, port is %d\n", port);
  73         snprintf(port_s, 6, "%d", port);
  74         GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", port_s, NULL);
  75 }
  76
  77 void unhijack(unsigned short port) {
  78         char port_s[6];
  79
  80         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "unHijacking, port is %d\n", port);
  81         snprintf(port_s, 6, "%d", port);
  82         GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", "-d", port_s, NULL);
  83 }
  84
  85 size_t send_answer(void* cls, size_t size, void* buf);
  86
  87 struct receive_dht_cls {
  88   unsigned short id;
  89   struct GNUNET_DHT_GetHandle* handle;
  90 };
  91
  92 void receive_dht(void *cls,
  93                  struct GNUNET_TIME_Absolute exp,
  94                  const GNUNET_HashCode *key,
  95                  const struct GNUNET_PeerIdentity *const *get_path,
  96                  const struct GNUNET_PeerIdentity *const *put_path,
  97                  enum GNUNET_BLOCK_Type type,
  98                  size_t size,
  99                  const void *data)
 100 {
 101   unsigned short id = ((struct receive_dht_cls*)cls)->id;
 102   struct GNUNET_DHT_GetHandle* handle = ((struct receive_dht_cls*)cls)->handle;
 103   GNUNET_free(cls);
 104
 105   GNUNET_assert(type == GNUNET_BLOCK_TYPE_DNS);
 106
 107   if (query_states[id].valid != GNUNET_YES) return;
 108   query_states[id].valid = GNUNET_NO;
 109
 110   const struct GNUNET_DNS_Record* rec = data;
 111   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Got block of size %d, peer: %08x, desc: %08x\n", size, *((unsigned int*)&rec->peer), *((unsigned int*)&rec->service_descriptor));
 112
 113   size_t len = sizeof(struct answer_packet) - 1 \
 114                + sizeof(struct dns_static) \
 115                + query_states[id].namelen \
 116                + sizeof(struct dns_query_line) \
 117                + 2 /* To hold the pointer to the name */ \
 118                + sizeof(struct dns_record_line) - 1 \
 119                + 16;
 120                ;
 121   struct answer_packet_list* answer = GNUNET_malloc(len + 2*sizeof(struct answer_packet_list*));
 122   memset(answer, 0, len + 2*sizeof(struct answer_packet_list*));
 123
 124   answer->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS);
 125   answer->pkt.hdr.size = htons(len);
 126   answer->pkt.subtype = GNUNET_DNS_ANSWER_TYPE_SERVICE;
 127
 128   GNUNET_CRYPTO_hash(&rec->peer, sizeof(struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded), &answer->pkt.peer);
 129   memcpy(&answer->pkt.service_descriptor, &rec->service_descriptor, sizeof(GNUNET_HashCode));
 130   memcpy(&answer->pkt.service_type, &rec->service_type, sizeof(answer->pkt.service_type));
 131   memcpy(&answer->pkt.ports, &rec->ports, sizeof(answer->pkt.ports));
 132
 133   answer->pkt.from = query_states[id].remote_ip;
 134
 135   answer->pkt.to = query_states[id].local_ip;
 136   answer->pkt.dst_port = query_states[id].local_port;
 137
 138   struct dns_pkt *dpkt = (struct dns_pkt*)answer->pkt.data;
 139
 140   dpkt->s.id = id;
 141   dpkt->s.aa = 1;
 142   dpkt->s.qr = 1;
 143   dpkt->s.ra = 1;
 144   dpkt->s.qdcount = htons(1);
 145   dpkt->s.ancount = htons(1);
 146
 147   memcpy(dpkt->data, query_states[id].name, query_states[id].namelen);
 148   GNUNET_free(query_states[id].name);
 149
 150
 151   struct dns_query_line* dque = (struct dns_query_line*)(dpkt->data+(query_states[id].namelen));
 152   dque->type = htons(28);
 153   dque->class = htons(1);
 154
 155   char* anname = (char*)(dpkt->data+(query_states[id].namelen)+sizeof(struct dns_query_line));
 156   memcpy(anname, (char[]){0xc0, 0x0c}, 2);
 157
 158   struct dns_record_line *drec_data = (struct dns_record_line*)(dpkt->data+(query_states[id].namelen)+sizeof(struct dns_query_line)+2);
 159   drec_data->type = htons(28); /* AAAA */
 160   drec_data->class = htons(1); /* IN */
 161   drec_data->ttl = htonl(3600); /* FIXME: read from block */
 162   drec_data->data_len = htons(16);
 163
 164   answer->pkt.addroffset = htons((unsigned short)((unsigned long)(&drec_data->data)-(unsigned long)(&answer->pkt)));
 165
 166   GNUNET_CONTAINER_DLL_insert_after(mycls.head, mycls.tail, mycls.tail, answer);
 167
 168   GNUNET_SERVER_notify_transmit_ready(query_states[id].client,
 169                                       len,
 170                                       GNUNET_TIME_UNIT_FOREVER_REL,
 171                                       &send_answer,
 172                                       query_states[id].client);
 173
 174   GNUNET_DHT_get_stop(handle);
 175 }
 176
 177 /**
 178  * This receives a GNUNET_MESSAGE_TYPE_REHIJACK and rehijacks the DNS
 179  */
 180 void rehijack(void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message) {
 181     unhijack(mycls.dnsoutport);
 182     hijack(mycls.dnsoutport);
 183 }
 184
 185 /**
 186  * This receives the dns-payload from the daemon-vpn and sends it on over the udp-socket
 187  */
 188 void receive_query(void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message)
 189 {
 190         struct query_packet* pkt = (struct query_packet*)message;
 191         struct dns_pkt* dns = (struct dns_pkt*)pkt->data;
 192         struct dns_pkt_parsed* pdns = parse_dns_packet(dns);
 193
 194         query_states[dns->s.id].valid = GNUNET_YES;
 195         query_states[dns->s.id].client = client;
 196         query_states[dns->s.id].local_ip = pkt->orig_from;
 197         query_states[dns->s.id].local_port = pkt->src_port;
 198         query_states[dns->s.id].remote_ip = pkt->orig_to;
 199         query_states[dns->s.id].namelen = strlen((char*)dns->data) + 1;
 200         query_states[dns->s.id].name = GNUNET_malloc(query_states[dns->s.id].namelen);
 201         memcpy(query_states[dns->s.id].name, dns->data, query_states[dns->s.id].namelen);
 202
 203         if (pdns->queries[0]->namelen > 9 &&
 204             0 == strncmp(pdns->queries[0]->name+(pdns->queries[0]->namelen - 9), ".gnunet.", 9)) {
 205
 206             GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Query for .gnunet!\n");
 207             GNUNET_HashCode key;
 208             GNUNET_CRYPTO_hash(pdns->queries[0]->name, pdns->queries[0]->namelen, &key);
 209
 210             GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Getting with key %08x, len is %d\n", *((unsigned int*)&key), pdns->queries[0]->namelen);
 211
 212             struct receive_dht_cls* cls = GNUNET_malloc(sizeof(struct receive_dht_cls));
 213             cls->id = dns->s.id;
 214
 215             cls->handle = GNUNET_DHT_get_start(mycls.dht,
 216                                  GNUNET_TIME_UNIT_MINUTES,
 217                                  GNUNET_BLOCK_TYPE_DNS,
 218                                  &key,
 219                                  GNUNET_DHT_RO_NONE,
 220                                  NULL,
 221                                  0,
 222                                  NULL,
 223                                  0,
 224                                  receive_dht,
 225                                  cls);
 226
 227             goto out;
 228         }
 229
 230         /* The query should be sent to the network */
 231         GNUNET_free(pdns);
 232
 233         struct sockaddr_in dest;
 234         memset(&dest, 0, sizeof dest);
 235         dest.sin_port = htons(53);
 236         dest.sin_addr.s_addr = pkt->orig_to;
 237
 238         /* int r = */ GNUNET_NETWORK_socket_sendto(mycls.dnsout, dns, ntohs(pkt->hdr.size) - sizeof(struct query_packet) + 1, (struct sockaddr*) &dest, sizeof dest);
 239
 240 out:
 241         GNUNET_SERVER_receive_done(client, GNUNET_OK);
 242 }
 243
 244 size_t send_answer(void* cls, size_t size, void* buf) {
 245         struct answer_packet_list* query = mycls.head;
 246         size_t len = ntohs(query->pkt.hdr.size);
 247
 248         GNUNET_assert(len <= size);
 249
 250         memcpy(buf, &query->pkt.hdr, len);
 251
 252         GNUNET_CONTAINER_DLL_remove (mycls.head, mycls.tail, query);
 253
 254         GNUNET_free(query);
 255
 256         if (mycls.head != NULL) {
 257                 GNUNET_SERVER_notify_transmit_ready(cls, ntohs(mycls.head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, &send_answer, cls);
 258         }
 259
 260         return len;
 261 }
 262
 263 static void read_response (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 264         unsigned char buf[65536];
 265         struct dns_pkt* dns = (struct dns_pkt*)buf;
 266
 267         if (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 268                 return;
 269
 270         struct sockaddr_in addr;
 271         memset(&addr, 0, sizeof addr);
 272         unsigned int addrlen = sizeof addr;
 273
 274         int r;
 275         r = GNUNET_NETWORK_socket_recvfrom(mycls.dnsout, buf, 65536, (struct sockaddr*)&addr, &addrlen);
 276
 277         /* if (r < 0) TODO */
 278
 279         if (query_states[dns->s.id].valid == GNUNET_YES) {
 280                 query_states[dns->s.id].valid = GNUNET_NO;
 281
 282                 size_t len = sizeof(struct answer_packet) + r - 1; /* 1 for the unsigned char data[1]; */
 283                 struct answer_packet_list* answer = GNUNET_malloc(len + 2*sizeof(struct answer_packet_list*));
 284                 answer->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS);
 285                 answer->pkt.hdr.size = htons(len);
 286                 answer->pkt.subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 287                 answer->pkt.from = addr.sin_addr.s_addr;
 288                 answer->pkt.to = query_states[dns->s.id].local_ip;
 289                 answer->pkt.dst_port = query_states[dns->s.id].local_port;
 290                 memcpy(answer->pkt.data, buf, r);
 291
 292                 GNUNET_CONTAINER_DLL_insert_after(mycls.head, mycls.tail, mycls.tail, answer);
 293
 294                 /* struct GNUNET_CONNECTION_TransmitHandle* th = */ GNUNET_SERVER_notify_transmit_ready(query_states[dns->s.id].client, len, GNUNET_TIME_UNIT_FOREVER_REL, &send_answer, query_states[dns->s.id].client);
 295         }
 296
 297         GNUNET_SCHEDULER_add_read_net(mycls.sched, GNUNET_TIME_UNIT_FOREVER_REL, mycls.dnsout, &read_response, NULL);
 298 }
 299
 300
 301 /**
 302  * Task run during shutdown.
 303  *
 304  * @param cls unused
 305  * @param tc unused
 306  */
 307 static void
 308 cleanup_task (void *cls,
 309               const struct GNUNET_SCHEDULER_TaskContext *tc)
 310 {
 311         unhijack(mycls.dnsoutport);
 312         GNUNET_DHT_disconnect(mycls.dht);
 313 }
 314
 315 static void
 316 publish_name (void *cls,
 317              const struct GNUNET_SCHEDULER_TaskContext *tc)
 318 {
 319   if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 320     return;
 321
 322   char* name = "philipptoelke.gnunet.";
 323   size_t size = sizeof(struct GNUNET_DNS_Record);
 324   struct GNUNET_DNS_Record data;
 325   memset(&data, 0, size);
 326
 327   data.purpose.size = htonl(size - sizeof(struct GNUNET_CRYPTO_RsaSignature));
 328   data.purpose.purpose = GNUNET_SIGNATURE_PURPOSE_DNS_RECORD;
 329
 330   GNUNET_CRYPTO_hash(name, strlen(name)+1, &data.service_descriptor);
 331
 332   char* keyfile;
 333   if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_filename(mycls.cfg, "GNUNETD",
 334                                                            "HOSTKEY", &keyfile))
 335     {
 336       GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "could not read keyfile-value\n");
 337       if (keyfile != NULL) GNUNET_free(keyfile);
 338       return;
 339     }
 340
 341   struct GNUNET_CRYPTO_RsaPrivateKey *my_private_key = GNUNET_CRYPTO_rsa_key_create_from_file(keyfile);
 342   GNUNET_free(keyfile);
 343
 344   GNUNET_CRYPTO_rsa_key_get_public(my_private_key, &data.peer);
 345
 346   data.expiration_time = GNUNET_TIME_relative_to_absolute(GNUNET_TIME_UNIT_HOURS);
 347
 348   /* Sign the block
 349    */
 350
 351   if (GNUNET_OK != GNUNET_CRYPTO_rsa_sign(my_private_key,
 352                                           &data.purpose,
 353                                           &data.signature))
 354     {
 355       GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "could not sign DNS_Record\n");
 356       return;
 357     }
 358   GNUNET_free(my_private_key);
 359
 360   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Putting with key %08x\n", *((unsigned int*)&data.service_descriptor));
 361
 362   GNUNET_DHT_put(mycls.dht,
 363                  &data.service_descriptor,
 364                  GNUNET_DHT_RO_NONE,
 365                  GNUNET_BLOCK_TYPE_DNS,
 366                  size,
 367                  (char*)&data,
 368                  GNUNET_TIME_relative_to_absolute(GNUNET_TIME_UNIT_HOURS),
 369                  GNUNET_TIME_UNIT_MINUTES,
 370                  NULL,
 371                  NULL);
 372
 373   GNUNET_SCHEDULER_add_delayed (mycls.sched, GNUNET_TIME_UNIT_HOURS, publish_name, NULL);
 374 }
 375
 376 /**
 377  * @param cls closure
 378  * @param sched scheduler to use
 379  * @param server the initialized server
 380  * @param cfg configuration to use
 381  */
 382 static void
 383 run (void *cls,
 384      struct GNUNET_SCHEDULER_Handle *sched,
 385      struct GNUNET_SERVER_Handle *server,
 386      const struct GNUNET_CONFIGURATION_Handle *cfg)
 387 {
 388   static const struct GNUNET_SERVER_MessageHandler handlers[] = {
 389           /* callback, cls, type, size */
 390     {&receive_query, NULL, GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS, 0},
 391     {&rehijack, NULL, GNUNET_MESSAGE_TYPE_REHIJACK, sizeof(struct GNUNET_MessageHeader)},
 392     {NULL, NULL, 0, 0}
 393   };
 394
 395   mycls.cfg = cfg;
 396
 397   {
 398   int i;
 399   for (i = 0; i < 65536; i++) {
 400     query_states[i].valid = GNUNET_NO;
 401   }
 402   }
 403
 404   mycls.dht = GNUNET_DHT_connect(sched, cfg, 1024);
 405
 406   struct sockaddr_in addr;
 407
 408   mycls.sched = sched;
 409   mycls.dnsout = GNUNET_NETWORK_socket_create (AF_INET, SOCK_DGRAM, 0);
 410   if (mycls.dnsout == NULL)
 411     return;
 412   memset(&addr, 0, sizeof(struct sockaddr_in));
 413
 414   int err = GNUNET_NETWORK_socket_bind (mycls.dnsout,
 415                                         (struct sockaddr*)&addr,
 416                                         sizeof(struct sockaddr_in));
 417
 418   if (err != GNUNET_YES) {
 419         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not bind a port, exiting\n");
 420         return;
 421   }
 422   socklen_t addrlen = sizeof(struct sockaddr_in);
 423   err = getsockname(GNUNET_NETWORK_get_fd(mycls.dnsout),
 424                     (struct sockaddr*) &addr,
 425                     &addrlen);
 426
 427   mycls.dnsoutport = htons(addr.sin_port);
 428
 429   hijack(htons(addr.sin_port));
 430
 431   GNUNET_SCHEDULER_add_now (mycls.sched, publish_name, NULL);
 432
 433         GNUNET_SCHEDULER_add_read_net(sched, GNUNET_TIME_UNIT_FOREVER_REL, mycls.dnsout, &read_response, NULL);
 434
 435   GNUNET_SERVER_add_handlers (server, handlers);
 436   GNUNET_SCHEDULER_add_delayed (sched,
 437                   GNUNET_TIME_UNIT_FOREVER_REL,
 438                   &cleanup_task,
 439                   cls);
 440 }
 441
 442 /**
 443  * The main function for the dns service.
 444  *
 445  * @param argc number of arguments from the command line
 446  * @param argv command line arguments
 447  * @return 0 ok, 1 on error
 448  */
 449 int
 450 main (int argc, char *const *argv)
 451 {
 452   return (GNUNET_OK ==
 453           GNUNET_SERVICE_run (argc,
 454                               argv,
 455                               "dns",
 456                               GNUNET_SERVICE_OPTION_NONE,
 457                               &run, NULL)) ? 0 : 1;
 458 }