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