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