src/vpn/gnunet-daemon-vpn.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2010 Christian Grothoff
   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-daemon-vpn.c
  23  * @brief
  24  * @author Philipp Toelke
  25  */
  26 #include "platform.h"
  27 #include "gnunet_getopt_lib.h"
  28 #include "gnunet_program_lib.h"
  29 #include "gnunet_os_lib.h"
  30 #include "gnunet-vpn-helper-p.h"
  31 #include "gnunet-vpn-packet.h"
  32 #include "gnunet-vpn-pretty-print.h"
  33 #include "gnunet_common.h"
  34 #include "gnunet_protocols.h"
  35 #include "gnunet_server_lib.h"
  36 #include "gnunet-service-dns-p.h"
  37 #include "gnunet_client_lib.h"
  38 #include "gnunet_container_lib.h"
  39 #include "block_dns.h"
  40
  41 /**
  42  * Final status code.
  43  */
  44 static int ret;
  45
  46 /**
  47  * The configuration to use
  48  */
  49 static const struct GNUNET_CONFIGURATION_Handle *cfg;
  50
  51 /**
  52  * PipeHandle to receive data from the helper
  53  */
  54 static struct GNUNET_DISK_PipeHandle* helper_in;
  55
  56 /**
  57  * PipeHandle to send data to the helper
  58  */
  59 static struct GNUNET_DISK_PipeHandle* helper_out;
  60
  61 /**
  62  * FileHandle to receive data from the helper
  63  */
  64 static const struct GNUNET_DISK_FileHandle* fh_from_helper;
  65
  66 /**
  67  * FileHandle to send data to the helper
  68  */
  69 static const struct GNUNET_DISK_FileHandle* fh_to_helper;
  70
  71 /**
  72  * The Message-Tokenizer that tokenizes the messages comming from the helper
  73  */
  74 static struct GNUNET_SERVER_MessageStreamTokenizer* mst;
  75
  76 /**
  77  * The connection to the service-dns
  78  */
  79 static struct GNUNET_CLIENT_Connection *dns_connection;
  80
  81 /**
  82  * A flag to show that the service-dns has to rehijack the outbound dns-packets
  83  *
  84  * This gets set when the helper restarts as the routing-tables are flushed when
  85  * the interface vanishes.
  86  */
  87 static unsigned char restart_hijack;
  88
  89 /**
  90  * The process id of the helper
  91  */
  92 static struct GNUNET_OS_Process *helper_proc;
  93
  94 /**
  95  * a list of outgoing dns-query-packets
  96  */
  97 static struct query_packet_list *head;
  98
  99 /**
 100  * The last element of the list of outgoing dns-query-packets
 101  */
 102 static struct query_packet_list *tail;
 103
 104 /**
 105  * A list of processed dns-responses.
 106  *
 107  * "processed" means that the packet is complete and can be sent out via udp
 108  * directly
 109  */
 110 static struct answer_packet_list *answer_proc_head;
 111
 112 /**
 113  * The last element of the list of processed dns-responses.
 114  */
 115 static struct answer_packet_list *answer_proc_tail;
 116
 117 /**
 118  * The hashmap containing the mappings from ipv6-addresses to gnunet-descriptors
 119  */
 120 static struct GNUNET_CONTAINER_MultiHashMap* hashmap;
 121
 122 static void helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx);
 123 static void dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg);
 124
 125 /**
 126  * Callback called by notify_transmit_ready; sends dns-queries or rehijack-messages
 127  * to the service-dns
 128  */
 129 static size_t
 130 send_query(void* cls, size_t size, void* buf) {
 131     size_t len;
 132     /*
 133      * Send the rehijack-message
 134      */
 135     if (restart_hijack == 1)
 136       {
 137         restart_hijack = 0;
 138         /*
 139          * The message is just a header
 140          */
 141         GNUNET_assert(sizeof(struct GNUNET_MessageHeader) <= size);
 142         struct GNUNET_MessageHeader* hdr = buf;
 143         len = sizeof(struct GNUNET_MessageHeader);
 144         hdr->size = htons(len);
 145         hdr->type = htons(GNUNET_MESSAGE_TYPE_REHIJACK);
 146       }
 147     else
 148       {
 149         struct query_packet_list* query = head;
 150         len = ntohs(query->pkt.hdr.size);
 151
 152         GNUNET_assert(len <= size);
 153
 154         memcpy(buf, &query->pkt.hdr, len);
 155
 156         GNUNET_CONTAINER_DLL_remove (head, tail, query);
 157
 158         GNUNET_free(query);
 159       }
 160
 161     /*
 162      * Check whether more data is to be sent
 163      */
 164     if (head != NULL)
 165       {
 166         GNUNET_CLIENT_notify_transmit_ready(dns_connection, ntohs(head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 167       }
 168     else if (restart_hijack == 1)
 169       {
 170         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 171       }
 172
 173     return len;
 174 }
 175
 176 /**
 177  * Function scheduled as very last function, cleans up after us
 178  */
 179 static void
 180 cleanup(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 181     GNUNET_assert (0 != (tskctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN));
 182
 183     /* stop the helper */
 184     if (helper_proc != NULL)
 185       {
 186         GNUNET_OS_process_kill (helper_proc, SIGTERM);
 187         GNUNET_OS_process_wait (helper_proc);
 188         GNUNET_OS_process_close (helper_proc);
 189         helper_proc = NULL;
 190       }
 191
 192     /* close the connection to the service-dns */
 193     if (dns_connection != NULL)
 194       {
 195         GNUNET_CLIENT_disconnect (dns_connection, GNUNET_NO);
 196         dns_connection = NULL;
 197       }
 198 }
 199
 200 /**
 201  * Start the helper-process
 202  */
 203 static void
 204 start_helper_and_schedule(void *cls,
 205                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
 206     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 207       return;
 208
 209     helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO);
 210     helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_NO, GNUNET_YES);
 211
 212     if (helper_in == NULL || helper_out == NULL) return;
 213
 214     helper_proc = GNUNET_OS_start_process(helper_in, helper_out, "gnunet-helper-vpn", "gnunet-helper-vpn", NULL);
 215
 216     fh_from_helper = GNUNET_DISK_pipe_handle (helper_out, GNUNET_DISK_PIPE_END_READ);
 217     fh_to_helper = GNUNET_DISK_pipe_handle (helper_in, GNUNET_DISK_PIPE_END_WRITE);
 218
 219     GNUNET_DISK_pipe_close_end(helper_out, GNUNET_DISK_PIPE_END_WRITE);
 220     GNUNET_DISK_pipe_close_end(helper_in, GNUNET_DISK_PIPE_END_READ);
 221
 222     /* Tell the dns-service to rehijack the dns-port
 223      * The routing-table gets flushed if an interface disappears.
 224      */
 225     restart_hijack = 1;
 226     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 227
 228     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 229 }
 230
 231 /**
 232  * Restart the helper-process
 233  */
 234 static void
 235 restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 236     // Kill the helper
 237     GNUNET_OS_process_kill (helper_proc, SIGKILL);
 238     GNUNET_OS_process_wait (helper_proc);
 239     GNUNET_OS_process_close (helper_proc);
 240     helper_proc = NULL;
 241
 242     GNUNET_DISK_pipe_close(helper_in);
 243     GNUNET_DISK_pipe_close(helper_out);
 244
 245     /* Restart the helper */
 246     GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS, start_helper_and_schedule, NULL);
 247 }
 248
 249 /**
 250  * Read from the helper-process
 251  */
 252 static void
 253 helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 254     /* no message can be bigger then 64k */
 255     char buf[65535];
 256
 257     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 258       return;
 259
 260     int t = GNUNET_DISK_file_read(fh_from_helper, &buf, 65535);
 261
 262     /* On read-error, restart the helper */
 263     if (t<=0) {
 264         GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Read error for header from vpn-helper: %m\n");
 265         GNUNET_SCHEDULER_add_now(restart_helper, cls);
 266         return;
 267     }
 268
 269     /* FIXME */ GNUNET_SERVER_mst_receive(mst, NULL, buf, t, 0, 0);
 270
 271     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 272 }
 273
 274 /**
 275  * Calculate the checksum of an IPv4-Header
 276  */
 277 static uint16_t
 278 calculate_ip_checksum(uint16_t* hdr, short len) {
 279     uint32_t sum = 0;
 280     for(; len >= 2; len -= 2)
 281       sum += *(hdr++);
 282     if (len == 1)
 283       sum += *((unsigned char*)hdr);
 284
 285     sum = (sum >> 16) + (sum & 0xFFFF);
 286
 287     return ~sum;
 288 }
 289
 290 /**
 291  * Send an dns-answer-packet to the helper
 292  */
 293 static void
 294 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 295     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 296       return;
 297
 298     struct answer_packet_list* ans = answer_proc_head;
 299     size_t len = ntohs(ans->pkt.hdr.size);
 300
 301     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 302
 303     size_t data_len = len - sizeof(struct answer_packet) + 1;
 304     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 305     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 306
 307     struct ip_udp_dns* pkt = alloca(pkt_len);
 308     memset(pkt, 0, pkt_len);
 309
 310     /* set the gnunet-header */
 311     pkt->shdr.size = htons(pkt_len);
 312     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 313
 314     /* set the tun-header (no flags and ethertype of IPv4) */
 315     pkt->tun.flags = 0;
 316     pkt->tun.type = htons(0x0800);
 317
 318     /* set the ip-header */
 319     pkt->ip_hdr.version = 4;
 320     pkt->ip_hdr.hdr_lngth = 5;
 321     pkt->ip_hdr.diff_serv = 0;
 322     pkt->ip_hdr.tot_lngth = htons(net_len);
 323     pkt->ip_hdr.ident = 0;
 324     pkt->ip_hdr.flags = 0;
 325     pkt->ip_hdr.frag_off = 0;
 326     pkt->ip_hdr.ttl = 255;
 327     pkt->ip_hdr.proto = 0x11; /* UDP */
 328     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 329     pkt->ip_hdr.sadr = ans->pkt.from;
 330     pkt->ip_hdr.dadr = ans->pkt.to;
 331
 332     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 333
 334     /* set the udp-header */
 335     pkt->udp_dns.udp_hdr.spt = htons(53);
 336     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 337     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 338     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 339
 340     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 341
 342     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 343     GNUNET_free(ans);
 344
 345     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, pkt, pkt_len);
 346
 347     /* if more packets are available, reschedule */
 348     if (answer_proc_head != NULL)
 349       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 350                                        fh_to_helper,
 351                                        &helper_write,
 352                                        NULL);
 353 }
 354
 355 /**
 356  * @return GNUNET_YES if a mapping exists
 357  */
 358 static int
 359 address_mapping_exists(unsigned char addr[]) {
 360     GNUNET_HashCode* key = alloca(sizeof(GNUNET_HashCode));
 361     memset(key, 0, sizeof(GNUNET_HashCode));
 362     memcpy(key, addr, 16);
 363
 364     return GNUNET_CONTAINER_multihashmap_contains(hashmap, key);
 365 }
 366
 367 static void
 368 send_icmp_response(void* cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 369     struct ip6_icmp* request = cls;
 370
 371     struct ip6_icmp* response = alloca(ntohs(request->shdr.size));
 372     memset(response, 0, ntohs(request->shdr.size));
 373
 374     response->shdr.size = request->shdr.size;
 375     response->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 376
 377     response->tun.flags = 0;
 378     response->tun.type = htons(0x86dd);
 379
 380     response->ip6_hdr.hoplmt = 255;
 381     response->ip6_hdr.paylgth = request->ip6_hdr.paylgth;
 382     response->ip6_hdr.nxthdr = 0x3a;
 383     response->ip6_hdr.version = 6;
 384     memcpy(&response->ip6_hdr.sadr, &request->ip6_hdr.dadr, 16);
 385     memcpy(&response->ip6_hdr.dadr, &request->ip6_hdr.sadr, 16);
 386
 387     response->icmp_hdr.code = 0;
 388     response->icmp_hdr.type = 0x81;
 389
 390     /* Magic, more Magic! */
 391     response->icmp_hdr.chks = request->icmp_hdr.chks - 0x1;
 392
 393     /* Copy the rest of the packet */
 394     memcpy(response+1, request+1, ntohs(request->shdr.size) - sizeof(struct ip6_icmp));
 395
 396     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, response, ntohs(response->shdr.size));
 397
 398     GNUNET_free(request);
 399 }
 400
 401 /**
 402  * Receive packets from the helper-process
 403  */
 404 static void
 405 message_token(void *cls,
 406               void *client,
 407               const struct GNUNET_MessageHeader *message) {
 408     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 409
 410     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 411
 412     /* ethertype is ipv6 */
 413     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 414       {
 415         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 416         GNUNET_assert(pkt6->ip6_hdr.version == 6);
 417         struct ip6_tcp *pkt6_tcp;
 418         struct ip6_udp *pkt6_udp;
 419         struct ip6_icmp *pkt6_icmp;
 420
 421         pkt_printf(pkt6);
 422         switch(pkt6->ip6_hdr.nxthdr)
 423           {
 424           case 0x06:
 425             pkt6_tcp = (struct ip6_tcp*)pkt6;
 426             pkt_printf_ip6tcp(pkt6_tcp);
 427             break;
 428           case 0x11:
 429             pkt6_udp = (struct ip6_udp*)pkt6;
 430             pkt_printf_ip6udp(pkt6_udp);
 431             if (ntohs(pkt6_udp->udp_hdr.dpt) == 53) {
 432                 pkt_printf_ip6dns((struct ip6_udp_dns*)pkt6_udp);
 433             }
 434             break;
 435           case 0x3a:
 436             /* ICMPv6 */
 437             pkt6_icmp = (struct ip6_icmp*)pkt6;
 438             /* If this packet is an icmp-echo-request and a mapping exists, answer */
 439             if (pkt6_icmp->icmp_hdr.type == 0x80 && address_mapping_exists(pkt6->ip6_hdr.dadr))
 440               {
 441                 pkt6_icmp = GNUNET_malloc(ntohs(pkt6->shdr.size));
 442                 memcpy(pkt6_icmp, pkt6, ntohs(pkt6->shdr.size));
 443                 GNUNET_SCHEDULER_add_now(&send_icmp_response, pkt6_icmp);
 444               }
 445             break;
 446           }
 447       }
 448     /* ethertype is ipv4 */
 449     else if (ntohs(pkt_tun->tun.type) == 0x0800)
 450       {
 451         struct ip_pkt *pkt = (struct ip_pkt*) message;
 452         struct ip_udp *udp = (struct ip_udp*) message;
 453         GNUNET_assert(pkt->ip_hdr.version == 4);
 454
 455         /* Send dns-packets to the service-dns */
 456         if (pkt->ip_hdr.proto == 0x11 && ntohs(udp->udp_hdr.dpt) == 53 )
 457           {
 458             /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 459             size_t len = sizeof(struct query_packet) + ntohs(udp->udp_hdr.len) - 9;
 460
 461             struct query_packet_list* query = GNUNET_malloc(len + 2*sizeof(struct query_packet_list*));
 462             query->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 463             query->pkt.hdr.size = htons(len);
 464             query->pkt.orig_to = pkt->ip_hdr.dadr;
 465             query->pkt.orig_from = pkt->ip_hdr.sadr;
 466             query->pkt.src_port = udp->udp_hdr.spt;
 467             memcpy(query->pkt.data, udp->data, ntohs(udp->udp_hdr.len) - 8);
 468
 469             GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, query);
 470
 471             if (dns_connection != NULL)
 472               GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 473                                                   len,
 474                                                   GNUNET_TIME_UNIT_FOREVER_REL,
 475                                                   GNUNET_YES,
 476                                                   &send_query,
 477                                                   NULL);
 478           }
 479       }
 480 }
 481
 482 /**
 483  * Connect to the service-dns
 484  */
 485 static void
 486 connect_to_service_dns (void *cls,
 487                         const struct GNUNET_SCHEDULER_TaskContext *tc) {
 488     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 489       return;
 490     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Connecting to service-dns\n");
 491     GNUNET_assert (dns_connection == NULL);
 492     dns_connection = GNUNET_CLIENT_connect ("dns", cfg);
 493     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 494
 495     /* If a packet is already in the list, schedule to send it */
 496     if (head != NULL)
 497       GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 498                                           ntohs(head->pkt.hdr.size),
 499                                           GNUNET_TIME_UNIT_FOREVER_REL,
 500                                           GNUNET_YES,
 501                                           &send_query,
 502                                           NULL);
 503     else if (restart_hijack == 1)
 504       {
 505         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 506       }
 507 }
 508
 509 /**
 510  * Create a new Address from an answer-packet
 511  * {{{
 512  */
 513 void
 514 new_ip6addr(char* buf, struct answer_packet* pkt) {
 515         memcpy(buf, (int[]){htons(0x1234)}, 2);
 516         memcpy(buf+2, &pkt->service_descr.service_descriptor, 6);
 517         memcpy(buf+8, &pkt->service_descr.peer, 8);
 518 }
 519 /*}}}*/
 520
 521 /**
 522  * This gets scheduled with cls pointing to an answer_packet and does everything
 523  * needed in order to send it to the helper.
 524  *
 525  * At the moment this means "inventing" and IPv6-Address for .gnunet-services and
 526  * doing nothing for "real" services.
 527  */
 528 static void
 529 process_answer(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tc) {
 530     struct answer_packet* pkt = cls;
 531     struct answer_packet_list* list;
 532
 533     /* This answer is about a .gnunet-service
 534      *
 535      * It contains an almost complete DNS-Response, we have to fill in the ip
 536      * at the offset pkt->addroffset
 537      */
 538     //FIXME htons?
 539     if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_SERVICE)
 540       {
 541         pkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 542
 543         GNUNET_HashCode key;
 544         memset(&key, 0, sizeof(GNUNET_HashCode));
 545         new_ip6addr((char*)&key, pkt);
 546
 547         struct GNUNET_vpn_service_descriptor* value = GNUNET_malloc(sizeof(struct GNUNET_vpn_service_descriptor));
 548         memcpy(value, &pkt->service_descr, sizeof(struct GNUNET_vpn_service_descriptor));
 549
 550         if (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put(hashmap,
 551                                                            &key,
 552                                                            value,
 553                                                            GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
 554           {
 555             GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not store to hashmap\n");
 556           }
 557
 558         memcpy(((char*)pkt)+ntohs(pkt->addroffset), &key, 16);
 559
 560           /*FIXME:
 561            * -save DNS_Record into hashmap, pointed to by ip
 562            * -regularily walk through hashmap, deleting old entries
 563            *  when is an entry old?
 564            *  have a last-used field
 565            *  don't remove if last-used "recent", ask dht again if record expired
 566            */
 567
 568         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 569
 570         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 571       }
 572     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_REV)
 573       {
 574         unsigned short offset = ntohs(pkt->addroffset);
 575
 576         unsigned short namelen = htons(22); /* calculate the length of the answer */
 577         char name[22] = {13, 'p', 'h', 'i', 'l', 'i', 'p', 'p', 't', 'o', 'e', 'l', 'k', 'e', 6, 'g', 'n', 'u', 'n', 'e', 't', 0};
 578
 579         list = GNUNET_malloc(2*sizeof(struct answer_packet_list*) + offset + 2 + ntohs(namelen));
 580
 581         struct answer_packet* rpkt = &list->pkt;
 582
 583         memcpy(rpkt, pkt, offset);
 584
 585         rpkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 586         rpkt->hdr.size = ntohs(offset + 2 + ntohs(namelen));
 587
 588         memcpy(((char*)rpkt)+offset, &namelen, 2);
 589         memcpy(((char*)rpkt)+offset+2, name, ntohs(namelen));
 590
 591       }
 592     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_IP)
 593       {
 594         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 595         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 596       }
 597     else
 598       {
 599         GNUNET_break(0);
 600         GNUNET_free(pkt);
 601         return;
 602       }
 603
 604     GNUNET_free(pkt);
 605
 606     GNUNET_CONTAINER_DLL_insert_after(answer_proc_head, answer_proc_tail, answer_proc_tail, list);
 607
 608     GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_to_helper, &helper_write, NULL);
 609
 610     return;
 611 }
 612
 613 /**
 614  * This receives packets from the service-dns and schedules process_answer to
 615  * handle it
 616  */
 617 static void
 618 dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg) {
 619     /* the service disconnected, reconnect after short wait */
 620     if (msg == NULL)
 621       {
 622         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 623         dns_connection = NULL;
 624         GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
 625                                       &connect_to_service_dns,
 626                                       NULL);
 627         return;
 628       }
 629
 630     /* the service did something strange, reconnect immediately */
 631     if (msg->type != htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS))
 632       {
 633         GNUNET_break (0);
 634         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 635         dns_connection = NULL;
 636         GNUNET_SCHEDULER_add_now (&connect_to_service_dns,
 637                                   NULL);
 638         return;
 639       }
 640     void *pkt = GNUNET_malloc(ntohs(msg->size));
 641
 642     memcpy(pkt, msg, ntohs(msg->size));
 643
 644     GNUNET_SCHEDULER_add_now(process_answer, pkt);
 645     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 646 }
 647
 648 /**
 649  * Main function that will be run by the scheduler.
 650  *
 651  * @param cls closure
 652  * @param args remaining command-line arguments
 653  * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 654  * @param cfg configuration
 655  */
 656 static void
 657 run (void *cls,
 658      char *const *args,
 659      const char *cfgfile,
 660      const struct GNUNET_CONFIGURATION_Handle *cfg_) {
 661     mst = GNUNET_SERVER_mst_create(&message_token, NULL);
 662     cfg = cfg_;
 663     restart_hijack = 0;
 664     hashmap = GNUNET_CONTAINER_multihashmap_create(65536);
 665     GNUNET_SCHEDULER_add_now (connect_to_service_dns, NULL);
 666     GNUNET_SCHEDULER_add_now (start_helper_and_schedule, NULL);
 667     GNUNET_SCHEDULER_add_delayed(GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls);
 668 }
 669
 670 /**
 671  * The main function to obtain template from gnunetd.
 672  *
 673  * @param argc number of arguments from the command line
 674  * @param argv command line arguments
 675  * @return 0 ok, 1 on error
 676  */
 677 int
 678 main (int argc, char *const *argv) {
 679     static const struct GNUNET_GETOPT_CommandLineOption options[] = {
 680         GNUNET_GETOPT_OPTION_END
 681     };
 682
 683     return (GNUNET_OK ==
 684             GNUNET_PROGRAM_run (argc,
 685                                 argv,
 686                                 "gnunet-daemon-vpn",
 687                                 gettext_noop ("help text"),
 688                                 options, &run, NULL)) ? ret : 1;
 689 }
 690
 691 /* end of gnunet-daemon-vpn.c */