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