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 /**
  43  * The scheduler to use throughout the service
  44  */
  45 static struct GNUNET_SCHEDULER_Handle *sched;
  46
  47 /**
  48  * The UDP-Socket through which DNS-Resolves will be sent if they are not to be
  49  * sent through gnunet. The port of this socket will not be hijacked.
  50  */
  51 static struct GNUNET_NETWORK_Handle *dnsout;
  52
  53 /**
  54  * The port bound to the socket dnsout
  55  */
  56 static unsigned short dnsoutport;
  57
  58 /**
  59  * A handle to the DHT-Service
  60  */
  61 static struct GNUNET_DHT_Handle *dht;
  62
  63 /**
  64  * The configuration to use
  65  */
  66 static const struct GNUNET_CONFIGURATION_Handle *cfg;
  67
  68 /**
  69  * A list of DNS-Responses that have to be sent to the requesting client
  70  */
  71 static struct answer_packet_list *head;
  72
  73 /**
  74  * The tail of the list of DNS-responses
  75  */
  76 static struct answer_packet_list *tail;
  77
  78 /**
  79  * A structure containing a mapping from network-byte-ordered DNS-id to
  80  * some information needed to handle this query
  81  *
  82  * It currently allocates at least
  83  * (1 + machine-width + 32 + 32 + 16 + machine-width + 8) * 65536 bit
  84  * = 1.7 MiB on 64 bit.
  85  * = 1.2 MiB on 32 bit.
  86  */
  87 static struct {
  88     unsigned valid:1;
  89     struct GNUNET_SERVER_Client* client;
  90     unsigned local_ip:32;
  91     unsigned remote_ip:32;
  92     unsigned local_port:16;
  93     char* name;
  94     unsigned namelen:8;
  95 } query_states[65536];
  96
  97 /**
  98  * A struct used to give more than one value as
  99  * closure to receive_dht
 100  */
 101 struct receive_dht_cls {
 102     unsigned short id;
 103     struct GNUNET_DHT_GetHandle* handle;
 104 };
 105
 106 /**
 107  * Hijack all outgoing DNS-Traffic but for traffic leaving "our" port.
 108  */
 109 static void
 110 hijack(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tc) {
 111     char port_s[6];
 112
 113     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Hijacking, port is %d\n", dnsoutport);
 114     snprintf(port_s, 6, "%d", dnsoutport);
 115     GNUNET_OS_process_close (GNUNET_OS_start_process(NULL,
 116                                                      NULL,
 117                                                      "gnunet-helper-hijack-dns",
 118                                                      "gnunet-hijack-dns",
 119                                                      port_s,
 120                                                      NULL));
 121 }
 122
 123 /**
 124  * Delete the hijacking-routes
 125  */
 126 static void
 127 unhijack(unsigned short port) {
 128     char port_s[6];
 129
 130     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "unHijacking, port is %d\n", port);
 131     snprintf(port_s, 6, "%d", port);
 132     GNUNET_OS_start_process(NULL,
 133                             NULL,
 134                             "gnunet-helper-hijack-dns",
 135                             "gnunet-hijack-dns",
 136                             "-d",
 137                             port_s,
 138                             NULL);
 139 }
 140
 141 /**
 142  * Send the DNS-Response to the client. Gets called via the notify_transmit_ready-
 143  * system.
 144  */
 145 static size_t
 146 send_answer(void* cls, size_t size, void* buf) {
 147     struct answer_packet_list* query = head;
 148     size_t len = ntohs(query->pkt.hdr.size);
 149
 150     GNUNET_assert(len <= size);
 151
 152     memcpy(buf, &query->pkt.hdr, len);
 153
 154     GNUNET_CONTAINER_DLL_remove (head, tail, query);
 155
 156     GNUNET_free(query);
 157
 158     /* When more data is to be sent, reschedule */
 159     if (head != NULL)
 160       GNUNET_SERVER_notify_transmit_ready(cls,
 161                                           ntohs(head->pkt.hdr.size),
 162                                           GNUNET_TIME_UNIT_FOREVER_REL,
 163                                           &send_answer,
 164                                           cls);
 165
 166     return len;
 167 }
 168
 169 /**
 170  * Receive a block from the dht.
 171  */
 172 static void
 173 receive_dht(void *cls,
 174             struct GNUNET_TIME_Absolute exp,
 175             const GNUNET_HashCode *key,
 176             const struct GNUNET_PeerIdentity *const *get_path,
 177             const struct GNUNET_PeerIdentity *const *put_path,
 178             enum GNUNET_BLOCK_Type type,
 179             size_t size,
 180             const void *data) {
 181
 182     unsigned short id = ((struct receive_dht_cls*)cls)->id;
 183     struct GNUNET_DHT_GetHandle* handle = ((struct receive_dht_cls*)cls)->handle;
 184     GNUNET_free(cls);
 185
 186     GNUNET_assert(type == GNUNET_BLOCK_TYPE_DNS);
 187
 188     /* If no query with this id is pending, ignore the block */
 189     if (query_states[id].valid != GNUNET_YES) return;
 190     query_states[id].valid = GNUNET_NO;
 191
 192     const struct GNUNET_DNS_Record* rec = data;
 193     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 194                "Got block of size %d, peer: %08x, desc: %08x\n",
 195                size,
 196                *((unsigned int*)&rec->peer),
 197                *((unsigned int*)&rec->service_descriptor));
 198
 199     size_t len = sizeof(struct answer_packet) - 1 \
 200                  + sizeof(struct dns_static) \
 201                  + query_states[id].namelen \
 202                  + sizeof(struct dns_query_line) \
 203                  + 2 /* To hold the pointer (as defined in RFC1035) to the name */ \
 204                  + sizeof(struct dns_record_line) - 1 \
 205                  + 16; /* To hold the IPv6-Address */
 206
 207     struct answer_packet_list* answer = GNUNET_malloc(len + 2*sizeof(struct answer_packet_list*));
 208     memset(answer, 0, len + 2*sizeof(struct answer_packet_list*));
 209
 210     answer->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS);
 211     answer->pkt.hdr.size = htons(len);
 212     answer->pkt.subtype = GNUNET_DNS_ANSWER_TYPE_SERVICE;
 213
 214     GNUNET_CRYPTO_hash(&rec->peer,
 215                        sizeof(struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
 216                        &answer->pkt.peer);
 217
 218     memcpy(&answer->pkt.service_descriptor,
 219            &rec->service_descriptor,
 220            sizeof(GNUNET_HashCode));
 221     memcpy(&answer->pkt.service_type,
 222            &rec->service_type,
 223            sizeof(answer->pkt.service_type));
 224     memcpy(&answer->pkt.ports, &rec->ports, sizeof(answer->pkt.ports));
 225
 226     answer->pkt.from = query_states[id].remote_ip;
 227
 228     answer->pkt.to = query_states[id].local_ip;
 229     answer->pkt.dst_port = query_states[id].local_port;
 230
 231     struct dns_pkt *dpkt = (struct dns_pkt*)answer->pkt.data;
 232
 233     dpkt->s.id = id;
 234     dpkt->s.aa = 1;
 235     dpkt->s.qr = 1;
 236     dpkt->s.ra = 1;
 237     dpkt->s.qdcount = htons(1);
 238     dpkt->s.ancount = htons(1);
 239
 240     memcpy(dpkt->data, query_states[id].name, query_states[id].namelen);
 241     GNUNET_free(query_states[id].name);
 242
 243
 244     struct dns_query_line* dque = (struct dns_query_line*)(dpkt->data+(query_states[id].namelen));
 245     dque->type = htons(28); /* AAAA */
 246     dque->class = htons(1); /* IN */
 247
 248     char* anname = (char*)(dpkt->data+(query_states[id].namelen)+sizeof(struct dns_query_line));
 249     memcpy(anname, (char[]){0xc0, 0x0c}, 2);
 250
 251     struct dns_record_line *drec_data = (struct dns_record_line*)(dpkt->data+(query_states[id].namelen)+sizeof(struct dns_query_line)+2);
 252     drec_data->type = htons(28); /* AAAA */
 253     drec_data->class = htons(1); /* IN */
 254     drec_data->ttl = htonl(3600); /* FIXME: read from block */
 255     drec_data->data_len = htons(16);
 256
 257     /* Calculate at which offset in the packet the IPv6-Address belongs, it is
 258      * filled in by the daemon-vpn */
 259     answer->pkt.addroffset = htons((unsigned short)((unsigned long)(&drec_data->data)-(unsigned long)(&answer->pkt)));
 260
 261     GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, answer);
 262
 263     GNUNET_SERVER_notify_transmit_ready(query_states[id].client,
 264                                         len,
 265                                         GNUNET_TIME_UNIT_FOREVER_REL,
 266                                         &send_answer,
 267                                         query_states[id].client);
 268
 269     GNUNET_DHT_get_stop(handle);
 270 }
 271
 272 /**
 273  * This receives a GNUNET_MESSAGE_TYPE_REHIJACK and rehijacks the DNS
 274  */
 275 static void
 276 rehijack(void *cls,
 277          struct GNUNET_SERVER_Client *client,
 278          const struct GNUNET_MessageHeader *message) {
 279     unhijack(dnsoutport);
 280     GNUNET_SCHEDULER_add_delayed(sched, GNUNET_TIME_UNIT_SECONDS, hijack, NULL);
 281
 282     GNUNET_SERVER_receive_done(client, GNUNET_OK);
 283 }
 284
 285 /**
 286  * This receives the dns-payload from the daemon-vpn and sends it on over the udp-socket
 287  */
 288 static void
 289 receive_query(void *cls,
 290               struct GNUNET_SERVER_Client *client,
 291               const struct GNUNET_MessageHeader *message) {
 292     struct query_packet* pkt = (struct query_packet*)message;
 293     struct dns_pkt* dns = (struct dns_pkt*)pkt->data;
 294     struct dns_pkt_parsed* pdns = parse_dns_packet(dns);
 295
 296     query_states[dns->s.id].valid = GNUNET_YES;
 297     query_states[dns->s.id].client = client;
 298     query_states[dns->s.id].local_ip = pkt->orig_from;
 299     query_states[dns->s.id].local_port = pkt->src_port;
 300     query_states[dns->s.id].remote_ip = pkt->orig_to;
 301     query_states[dns->s.id].namelen = strlen((char*)dns->data) + 1;
 302     query_states[dns->s.id].name = GNUNET_malloc(query_states[dns->s.id].namelen);
 303     memcpy(query_states[dns->s.id].name, dns->data, query_states[dns->s.id].namelen);
 304
 305     if (pdns->queries[0]->namelen > 9 &&
 306         0 == strncmp(pdns->queries[0]->name+(pdns->queries[0]->namelen - 9), ".gnunet.", 9))
 307       {
 308         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Query for .gnunet!\n");
 309         GNUNET_HashCode key;
 310         GNUNET_CRYPTO_hash(pdns->queries[0]->name, pdns->queries[0]->namelen, &key);
 311
 312         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 313                    "Getting with key %08x, len is %d\n",
 314                    *((unsigned int*)&key),
 315                    pdns->queries[0]->namelen);
 316
 317         struct receive_dht_cls* cls = GNUNET_malloc(sizeof(struct receive_dht_cls));
 318         cls->id = dns->s.id;
 319
 320         cls->handle = GNUNET_DHT_get_start(dht,
 321                                            GNUNET_TIME_UNIT_MINUTES,
 322                                            GNUNET_BLOCK_TYPE_DNS,
 323                                            &key,
 324                                            GNUNET_DHT_RO_NONE,
 325                                            NULL,
 326                                            0,
 327                                            NULL,
 328                                            0,
 329                                            receive_dht,
 330                                            cls);
 331
 332         goto out;
 333       }
 334
 335     /* The query should be sent to the network */
 336
 337     struct sockaddr_in dest;
 338     memset(&dest, 0, sizeof dest);
 339     dest.sin_port = htons(53);
 340     dest.sin_addr.s_addr = pkt->orig_to;
 341
 342     GNUNET_NETWORK_socket_sendto(dnsout,
 343                                  dns,
 344                                  ntohs(pkt->hdr.size) - sizeof(struct query_packet) + 1,
 345                                  (struct sockaddr*) &dest,
 346                                  sizeof dest);
 347
 348 out:
 349     free_parsed_dns_packet(pdns);
 350     pdns = NULL;
 351     GNUNET_SERVER_receive_done(client, GNUNET_OK);
 352 }
 353
 354 /**
 355  * Read a response-packet of the UDP-Socket
 356  */
 357 static void
 358 read_response (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 359     unsigned char buf[65536];
 360     struct dns_pkt* dns = (struct dns_pkt*)buf;
 361
 362     if (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 363       return;
 364
 365     struct sockaddr_in addr;
 366     memset(&addr, 0, sizeof addr);
 367     unsigned int addrlen = sizeof addr;
 368
 369     int r;
 370     r = GNUNET_NETWORK_socket_recvfrom(dnsout,
 371                                        buf,
 372                                        65536,
 373                                        (struct sockaddr*)&addr,
 374                                        &addrlen);
 375
 376     /* if (r < 0) FIXME */
 377
 378     if (query_states[dns->s.id].valid == GNUNET_YES) {
 379         query_states[dns->s.id].valid = GNUNET_NO;
 380
 381         size_t len = sizeof(struct answer_packet) + r - 1; /* 1 for the unsigned char data[1]; */
 382         struct answer_packet_list* answer = GNUNET_malloc(len + 2*sizeof(struct answer_packet_list*));
 383         answer->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS);
 384         answer->pkt.hdr.size = htons(len);
 385         answer->pkt.subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 386         answer->pkt.from = addr.sin_addr.s_addr;
 387         answer->pkt.to = query_states[dns->s.id].local_ip;
 388         answer->pkt.dst_port = query_states[dns->s.id].local_port;
 389         memcpy(answer->pkt.data, buf, r);
 390
 391         GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, answer);
 392
 393         GNUNET_SERVER_notify_transmit_ready(query_states[dns->s.id].client,
 394                                             len,
 395                                             GNUNET_TIME_UNIT_FOREVER_REL,
 396                                             &send_answer,
 397                                             query_states[dns->s.id].client);
 398     }
 399
 400     GNUNET_SCHEDULER_add_read_net(sched,
 401                                   GNUNET_TIME_UNIT_FOREVER_REL,
 402                                   dnsout,
 403                                   &read_response,
 404                                   NULL);
 405 }
 406
 407
 408 /**
 409  * Task run during shutdown.
 410  *
 411  * @param cls unused
 412  * @param tc unused
 413  */
 414 static void
 415 cleanup_task (void *cls,
 416               const struct GNUNET_SCHEDULER_TaskContext *tc)
 417 {
 418   unhijack(dnsoutport);
 419   GNUNET_DHT_disconnect(dht);
 420 }
 421
 422 /**
 423  * Publish a DNS-record in the DHT. This is up to now just for testing.
 424  */
 425 static void
 426 publish_name (void *cls,
 427               const struct GNUNET_SCHEDULER_TaskContext *tc) {
 428     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 429       return;
 430
 431     char* name = "philipptoelke.gnunet.";
 432     size_t size = sizeof(struct GNUNET_DNS_Record);
 433     struct GNUNET_DNS_Record data;
 434     memset(&data, 0, size);
 435
 436     data.purpose.size = htonl(size - sizeof(struct GNUNET_CRYPTO_RsaSignature));
 437     data.purpose.purpose = GNUNET_SIGNATURE_PURPOSE_DNS_RECORD;
 438
 439     GNUNET_CRYPTO_hash(name, strlen(name)+1, &data.service_descriptor);
 440
 441     char* keyfile;
 442     if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_filename(cfg, "GNUNETD",
 443                                                              "HOSTKEY", &keyfile))
 444       {
 445         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "could not read keyfile-value\n");
 446         if (keyfile != NULL) GNUNET_free(keyfile);
 447         return;
 448       }
 449
 450     struct GNUNET_CRYPTO_RsaPrivateKey *my_private_key = GNUNET_CRYPTO_rsa_key_create_from_file(keyfile);
 451     GNUNET_free(keyfile);
 452
 453     GNUNET_CRYPTO_rsa_key_get_public(my_private_key, &data.peer);
 454
 455     data.expiration_time = GNUNET_TIME_relative_to_absolute(GNUNET_TIME_UNIT_HOURS);
 456
 457   /* Sign the block */
 458     if (GNUNET_OK != GNUNET_CRYPTO_rsa_sign(my_private_key,
 459                                             &data.purpose,
 460                                             &data.signature))
 461       {
 462         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "could not sign DNS_Record\n");
 463         return;
 464       }
 465     GNUNET_CRYPTO_rsa_key_free(my_private_key);
 466
 467     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
 468                "Putting with key %08x\n",
 469                *((unsigned int*)&data.service_descriptor));
 470
 471     GNUNET_DHT_put(dht,
 472                    &data.service_descriptor,
 473                    GNUNET_DHT_RO_NONE,
 474                    GNUNET_BLOCK_TYPE_DNS,
 475                    size,
 476                    (char*)&data,
 477                    GNUNET_TIME_relative_to_absolute(GNUNET_TIME_UNIT_HOURS),
 478                    GNUNET_TIME_UNIT_MINUTES,
 479                    NULL,
 480                    NULL);
 481
 482     GNUNET_SCHEDULER_add_delayed (sched,
 483                                   GNUNET_TIME_UNIT_HOURS,
 484                                   publish_name,
 485                                   NULL);
 486 }
 487
 488 /**
 489  * @param cls closure
 490  * @param sched scheduler to use
 491  * @param server the initialized server
 492  * @param cfg configuration to use
 493  */
 494 static void
 495 run (void *cls,
 496      struct GNUNET_SCHEDULER_Handle *sched_,
 497      struct GNUNET_SERVER_Handle *server,
 498      const struct GNUNET_CONFIGURATION_Handle *cfg_)
 499 {
 500   static const struct GNUNET_SERVER_MessageHandler handlers[] = {
 501       /* callback, cls, type, size */
 502         {&receive_query, NULL, GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS, 0},
 503         {&rehijack, NULL, GNUNET_MESSAGE_TYPE_REHIJACK, sizeof(struct GNUNET_MessageHeader)},
 504         {NULL, NULL, 0, 0}
 505   };
 506
 507   cfg = cfg_;
 508   sched = sched_;
 509
 510   unsigned int i;
 511   for (i = 0; i < 65536; i++) {
 512       query_states[i].valid = GNUNET_NO;
 513   }
 514
 515   dht = GNUNET_DHT_connect(sched, cfg, 1024);
 516
 517   struct sockaddr_in addr;
 518
 519   dnsout = GNUNET_NETWORK_socket_create (AF_INET, SOCK_DGRAM, 0);
 520   if (dnsout == NULL)
 521     return;
 522   memset(&addr, 0, sizeof(struct sockaddr_in));
 523
 524   int err = GNUNET_NETWORK_socket_bind (dnsout,
 525                                         (struct sockaddr*)&addr,
 526                                         sizeof(struct sockaddr_in));
 527
 528   if (err != GNUNET_YES) {
 529       GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not bind a port, exiting\n");
 530       return;
 531   }
 532
 533   /* Read the port we bound to */
 534   socklen_t addrlen = sizeof(struct sockaddr_in);
 535   err = getsockname(GNUNET_NETWORK_get_fd(dnsout),
 536                     (struct sockaddr*) &addr,
 537                     &addrlen);
 538
 539   dnsoutport = htons(addr.sin_port);
 540
 541   GNUNET_SCHEDULER_add_now (sched, publish_name, NULL);
 542
 543   GNUNET_SCHEDULER_add_read_net(sched, GNUNET_TIME_UNIT_FOREVER_REL, dnsout, &read_response, NULL);
 544
 545   GNUNET_SERVER_add_handlers (server, handlers);
 546   GNUNET_SCHEDULER_add_delayed (sched,
 547                                 GNUNET_TIME_UNIT_FOREVER_REL,
 548                                 &cleanup_task,
 549                                 cls);
 550 }
 551
 552 /**
 553  * The main function for the dns service.
 554  *
 555  * @param argc number of arguments from the command line
 556  * @param argv command line arguments
 557  * @return 0 ok, 1 on error
 558  */
 559 int
 560 main (int argc, char *const *argv)
 561 {
 562   return (GNUNET_OK ==
 563           GNUNET_SERVICE_run (argc,
 564                               argv,
 565                               "dns",
 566                               GNUNET_SERVICE_OPTION_NONE,
 567                               &run, NULL)) ? 0 : 1;
 568 }