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