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 "gnunet_block_dns.h"
  39
  40 struct dns_cls {
  41         struct GNUNET_SCHEDULER_Handle *sched;
  42
  43         struct GNUNET_NETWORK_Handle *dnsout;
  44
  45         struct GNUNET_DHT_Handle *dht;
  46
  47         unsigned short dnsoutport;
  48
  49         struct answer_packet_list *head;
  50         struct answer_packet_list *tail;
  51 };
  52 static struct dns_cls mycls;
  53
  54 struct dns_query_id_state {
  55         unsigned valid:1;
  56         struct GNUNET_SERVER_Client* client;
  57         unsigned local_ip:32;
  58         unsigned remote_ip:32;
  59         unsigned local_port:16;
  60 };
  61 static struct dns_query_id_state query_states[65536]; /* This is < 1.5MiB */
  62
  63 void hijack(unsigned short port) {
  64         char port_s[6];
  65
  66         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Hijacking, port is %d\n", port);
  67         snprintf(port_s, 6, "%d", port);
  68         GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", port_s, NULL);
  69 }
  70
  71 void unhijack(unsigned short port) {
  72         char port_s[6];
  73
  74         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "unHijacking, port is %d\n", port);
  75         snprintf(port_s, 6, "%d", port);
  76         GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", "-d", port_s, NULL);
  77 }
  78
  79 size_t send_answer(void* cls, size_t size, void* buf);
  80
  81 struct receive_dht_cls {
  82   unsigned short id;
  83   struct GNUNET_DHT_GetHandle* handle;
  84 };
  85
  86 void receive_dht(void *cls,
  87                  struct GNUNET_TIME_Absolute exp,
  88                  const GNUNET_HashCode *key,
  89                  const struct GNUNET_PeerIdentity *const *get_path,
  90                  const struct GNUNET_PeerIdentity *const *put_path,
  91                  enum GNUNET_BLOCK_Type type,
  92                  size_t size,
  93                  const void *data)
  94 {
  95   unsigned short id = ((struct receive_dht_cls*)cls)->id;
  96   struct GNUNET_DHT_GetHandle* handle = ((struct receive_dht_cls*)cls)->handle;
  97   GNUNET_free(cls);
  98
  99   GNUNET_assert(type == GNUNET_BLOCK_TYPE_DNS);
 100
 101   if (query_states[id].valid != GNUNET_YES) return;
 102   query_states[id].valid = GNUNET_NO;
 103
 104   const struct GNUNET_DNS_Record* rec = data;
 105   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));
 106
 107   size_t len = sizeof(struct answer_packet) + size - 1; /* 1 for the unsigned char data[1]; */
 108   struct answer_packet_list* answer = GNUNET_malloc(len + 2*sizeof(struct answer_packet_list*));
 109   answer->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS);
 110   answer->pkt.hdr.size = htons(len);
 111   answer->pkt.subtype = GNUNET_DNS_ANSWER_TYPE_SERVICE;
 112
 113   answer->pkt.from = query_states[id].remote_ip;
 114
 115   answer->pkt.to = query_states[id].local_ip;
 116   answer->pkt.dst_port = query_states[id].local_port;
 117
 118   answer->pkt.id = id;
 119
 120   memcpy(answer->pkt.data, data, size);
 121
 122   GNUNET_CONTAINER_DLL_insert_after(mycls.head, mycls.tail, mycls.tail, answer);
 123
 124   GNUNET_SERVER_notify_transmit_ready(query_states[id].client,
 125                                       len,
 126                                       GNUNET_TIME_UNIT_FOREVER_REL,
 127                                       &send_answer,
 128                                       query_states[id].client);
 129
 130   GNUNET_DHT_get_stop(handle);
 131 }
 132
 133 /**
 134  * This receives the dns-payload from the daemon-vpn and sends it on over the udp-socket
 135  */
 136 void receive_query(void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message)
 137 {
 138         struct query_packet* pkt = (struct query_packet*)message;
 139         struct dns_pkt* dns = (struct dns_pkt*)pkt->data;
 140         struct dns_pkt_parsed* pdns = parse_dns_packet(dns);
 141
 142         query_states[dns->s.id].valid = GNUNET_YES;
 143         query_states[dns->s.id].client = client;
 144         query_states[dns->s.id].local_ip = pkt->orig_from;
 145         query_states[dns->s.id].local_port = pkt->src_port;
 146         query_states[dns->s.id].remote_ip = pkt->orig_to;
 147
 148         if (pdns->queries[0]->namelen > 9 &&
 149             0 == strncmp(pdns->queries[0]->name+(pdns->queries[0]->namelen - 9), ".gnunet.", 9)) {
 150
 151             GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Query for .gnunet!\n");
 152             GNUNET_HashCode key;
 153             GNUNET_CRYPTO_hash(pdns->queries[0]->name, pdns->queries[0]->namelen, &key);
 154
 155             GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Getting with key %08x, len is %d\n", *((unsigned int*)&key), pdns->queries[0]->namelen);
 156
 157             struct receive_dht_cls* cls = GNUNET_malloc(sizeof(struct receive_dht_cls));
 158             cls->id = dns->s.id;
 159
 160             cls->handle = GNUNET_DHT_get_start(mycls.dht,
 161                                  GNUNET_TIME_UNIT_MINUTES,
 162                                  GNUNET_BLOCK_TYPE_DNS,
 163                                  &key,
 164                                  GNUNET_DHT_RO_NONE,
 165                                  NULL,
 166                                  0,
 167                                  NULL,
 168                                  0,
 169                                  receive_dht,
 170                                  cls);
 171
 172             goto out;
 173         }
 174
 175         /* The query should be sent to the network */
 176         GNUNET_free(pdns);
 177
 178         struct sockaddr_in dest;
 179         memset(&dest, 0, sizeof dest);
 180         dest.sin_port = htons(53);
 181         dest.sin_addr.s_addr = pkt->orig_to;
 182
 183         /* int r = */ GNUNET_NETWORK_socket_sendto(mycls.dnsout, dns, ntohs(pkt->hdr.size) - sizeof(struct query_packet) + 1, (struct sockaddr*) &dest, sizeof dest);
 184
 185 out:
 186         GNUNET_SERVER_receive_done(client, GNUNET_OK);
 187 }
 188
 189 size_t send_answer(void* cls, size_t size, void* buf) {
 190         struct answer_packet_list* query = mycls.head;
 191         size_t len = ntohs(query->pkt.hdr.size);
 192
 193         GNUNET_assert(len <= size);
 194
 195         memcpy(buf, &query->pkt.hdr, len);
 196
 197         GNUNET_CONTAINER_DLL_remove (mycls.head, mycls.tail, query);
 198
 199         GNUNET_free(query);
 200
 201         if (mycls.head != NULL) {
 202                 GNUNET_SERVER_notify_transmit_ready(cls, ntohs(mycls.head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, &send_answer, cls);
 203         }
 204
 205         return len;
 206 }
 207
 208 static void read_response (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 209         unsigned char buf[65536];
 210         struct dns_pkt* dns = (struct dns_pkt*)buf;
 211
 212         if (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 213                 return;
 214
 215         struct sockaddr_in addr;
 216         memset(&addr, 0, sizeof addr);
 217         unsigned int addrlen = sizeof addr;
 218
 219         int r;
 220         r = GNUNET_NETWORK_socket_recvfrom(mycls.dnsout, buf, 65536, (struct sockaddr*)&addr, &addrlen);
 221
 222         /* if (r < 0) TODO */
 223
 224         if (query_states[dns->s.id].valid == GNUNET_YES) {
 225                 query_states[dns->s.id].valid = GNUNET_NO;
 226
 227                 size_t len = sizeof(struct answer_packet) + r - 1; /* 1 for the unsigned char data[1]; */
 228                 struct answer_packet_list* answer = GNUNET_malloc(len + 2*sizeof(struct answer_packet_list*));
 229                 answer->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS);
 230                 answer->pkt.hdr.size = htons(len);
 231                 answer->pkt.subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 232                 answer->pkt.from = addr.sin_addr.s_addr;
 233                 answer->pkt.to = query_states[dns->s.id].local_ip;
 234                 answer->pkt.dst_port = query_states[dns->s.id].local_port;
 235                 memcpy(answer->pkt.data, buf, r);
 236
 237                 GNUNET_CONTAINER_DLL_insert_after(mycls.head, mycls.tail, mycls.tail, answer);
 238
 239                 /* 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);
 240         }
 241
 242         GNUNET_SCHEDULER_add_read_net(mycls.sched, GNUNET_TIME_UNIT_FOREVER_REL, mycls.dnsout, &read_response, NULL);
 243 }
 244
 245
 246 /**
 247  * Task run during shutdown.
 248  *
 249  * @param cls unused
 250  * @param tc unused
 251  */
 252 static void
 253 cleanup_task (void *cls,
 254               const struct GNUNET_SCHEDULER_TaskContext *tc)
 255 {
 256         unhijack(mycls.dnsoutport);
 257         GNUNET_DHT_disconnect(mycls.dht);
 258 }
 259
 260 static void
 261 publish_name (void *cls,
 262              const struct GNUNET_SCHEDULER_TaskContext *tc)
 263 {
 264   if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 265     return;
 266
 267   char* name = "philipptoelke.gnunet.";
 268   size_t size = sizeof(struct GNUNET_DNS_Record) + strlen(name);
 269   struct GNUNET_DNS_Record *data = alloca(size);
 270   memset(data, 0, size);
 271   memcpy(data->name, name, strlen(name) + 1);
 272   data->namelen = strlen(name) + 1;
 273   *((unsigned int*)&data->service_descriptor) = 0x11223344;
 274   *((unsigned int*)&data->peer) = 0x55667788;
 275
 276   GNUNET_HashCode key;
 277   GNUNET_CRYPTO_hash(name, strlen(name)+1, &key);
 278   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Putting with key %08x, len is %d\n", *((unsigned int*)&key), strlen(name));
 279
 280   GNUNET_DHT_put(mycls.dht,
 281                       &key,
 282                       GNUNET_DHT_RO_NONE,
 283                       GNUNET_BLOCK_TYPE_DNS,
 284                       size,
 285                       (char*)data,
 286                       GNUNET_TIME_relative_to_absolute(GNUNET_TIME_UNIT_HOURS),
 287                       GNUNET_TIME_UNIT_MINUTES,
 288                       NULL,
 289                       NULL);
 290
 291   GNUNET_SCHEDULER_add_delayed (mycls.sched, GNUNET_TIME_UNIT_HOURS, publish_name, NULL);
 292 }
 293
 294 /**
 295  * @param cls closure
 296  * @param sched scheduler to use
 297  * @param server the initialized server
 298  * @param cfg configuration to use
 299  */
 300 static void
 301 run (void *cls,
 302      struct GNUNET_SCHEDULER_Handle *sched,
 303      struct GNUNET_SERVER_Handle *server,
 304      const struct GNUNET_CONFIGURATION_Handle *cfg)
 305 {
 306   static const struct GNUNET_SERVER_MessageHandler handlers[] = {
 307           /* callback, cls, type, size */
 308     {&receive_query, NULL, GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS, 0},
 309     {NULL, NULL, 0, 0}
 310   };
 311
 312   {
 313   int i;
 314   for (i = 0; i < 65536; i++) {
 315     query_states[i].valid = GNUNET_NO;
 316   }
 317   }
 318
 319   mycls.dht = GNUNET_DHT_connect(sched, cfg, 1024);
 320
 321   struct sockaddr_in addr;
 322
 323   mycls.sched = sched;
 324   mycls.dnsout = GNUNET_NETWORK_socket_create (AF_INET, SOCK_DGRAM, 0);
 325   if (mycls.dnsout == NULL)
 326     return;
 327   memset(&addr, 0, sizeof(struct sockaddr_in));
 328
 329   int err = GNUNET_NETWORK_socket_bind (mycls.dnsout,
 330                                         (struct sockaddr*)&addr,
 331                                         sizeof(struct sockaddr_in));
 332
 333   if (err != GNUNET_YES) {
 334         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not bind a port, exiting\n");
 335         return;
 336   }
 337   socklen_t addrlen = sizeof(struct sockaddr_in);
 338   err = getsockname(GNUNET_NETWORK_get_fd(mycls.dnsout),
 339                     (struct sockaddr*) &addr,
 340                     &addrlen);
 341
 342   mycls.dnsoutport = htons(addr.sin_port);
 343
 344   hijack(htons(addr.sin_port));
 345
 346   GNUNET_SCHEDULER_add_now (mycls.sched, publish_name, NULL);
 347
 348         GNUNET_SCHEDULER_add_read_net(sched, GNUNET_TIME_UNIT_FOREVER_REL, mycls.dnsout, &read_response, NULL);
 349
 350   GNUNET_SERVER_add_handlers (server, handlers);
 351   GNUNET_SCHEDULER_add_delayed (sched,
 352                   GNUNET_TIME_UNIT_FOREVER_REL,
 353                   &cleanup_task,
 354                   cls);
 355 }
 356
 357 /**
 358  * The main function for the dns service.
 359  *
 360  * @param argc number of arguments from the command line
 361  * @param argv command line arguments
 362  * @return 0 ok, 1 on error
 363  */
 364 int
 365 main (int argc, char *const *argv)
 366 {
 367   return (GNUNET_OK ==
 368           GNUNET_SERVICE_run (argc,
 369                               argv,
 370                               "dns",
 371                               GNUNET_SERVICE_OPTION_NONE,
 372                               &run, NULL)) ? 0 : 1;
 373 }