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 struct map_entry {
 123     struct GNUNET_vpn_service_descriptor desc;
 124     uint16_t namelen;
 125     /**
 126      * In DNS-Format!
 127      */
 128     char name[1];
 129 };
 130
 131 static void helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx);
 132 static void dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg);
 133
 134 /**
 135  * Callback called by notify_transmit_ready; sends dns-queries or rehijack-messages
 136  * to the service-dns
 137  */
 138 static size_t
 139 send_query(void* cls, size_t size, void* buf) {
 140     size_t len;
 141     /*
 142      * Send the rehijack-message
 143      */
 144     if (restart_hijack == 1)
 145       {
 146         restart_hijack = 0;
 147         /*
 148          * The message is just a header
 149          */
 150         GNUNET_assert(sizeof(struct GNUNET_MessageHeader) <= size);
 151         struct GNUNET_MessageHeader* hdr = buf;
 152         len = sizeof(struct GNUNET_MessageHeader);
 153         hdr->size = htons(len);
 154         hdr->type = htons(GNUNET_MESSAGE_TYPE_REHIJACK);
 155       }
 156     else
 157       {
 158         struct query_packet_list* query = head;
 159         len = ntohs(query->pkt.hdr.size);
 160
 161         GNUNET_assert(len <= size);
 162
 163         memcpy(buf, &query->pkt.hdr, len);
 164
 165         GNUNET_CONTAINER_DLL_remove (head, tail, query);
 166
 167         GNUNET_free(query);
 168       }
 169
 170     /*
 171      * Check whether more data is to be sent
 172      */
 173     if (head != NULL)
 174       {
 175         GNUNET_CLIENT_notify_transmit_ready(dns_connection, ntohs(head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 176       }
 177     else if (restart_hijack == 1)
 178       {
 179         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 180       }
 181
 182     return len;
 183 }
 184
 185 /**
 186  * Function scheduled as very last function, cleans up after us
 187  */
 188 static void
 189 cleanup(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 190     GNUNET_assert (0 != (tskctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN));
 191
 192     /* stop the helper */
 193     if (helper_proc != NULL)
 194       {
 195         GNUNET_OS_process_kill (helper_proc, SIGTERM);
 196         GNUNET_OS_process_wait (helper_proc);
 197         GNUNET_OS_process_close (helper_proc);
 198         helper_proc = NULL;
 199       }
 200
 201     /* close the connection to the service-dns */
 202     if (dns_connection != NULL)
 203       {
 204         GNUNET_CLIENT_disconnect (dns_connection, GNUNET_NO);
 205         dns_connection = NULL;
 206       }
 207 }
 208
 209 /**
 210  * Start the helper-process
 211  */
 212 static void
 213 start_helper_and_schedule(void *cls,
 214                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
 215     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 216       return;
 217
 218     helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO);
 219     helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_NO, GNUNET_YES);
 220
 221     if (helper_in == NULL || helper_out == NULL) return;
 222
 223     helper_proc = GNUNET_OS_start_process(helper_in, helper_out, "gnunet-helper-vpn", "gnunet-helper-vpn", NULL);
 224
 225     fh_from_helper = GNUNET_DISK_pipe_handle (helper_out, GNUNET_DISK_PIPE_END_READ);
 226     fh_to_helper = GNUNET_DISK_pipe_handle (helper_in, GNUNET_DISK_PIPE_END_WRITE);
 227
 228     GNUNET_DISK_pipe_close_end(helper_out, GNUNET_DISK_PIPE_END_WRITE);
 229     GNUNET_DISK_pipe_close_end(helper_in, GNUNET_DISK_PIPE_END_READ);
 230
 231     /* Tell the dns-service to rehijack the dns-port
 232      * The routing-table gets flushed if an interface disappears.
 233      */
 234     restart_hijack = 1;
 235     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 236
 237     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 238 }
 239
 240 /**
 241  * Restart the helper-process
 242  */
 243 static void
 244 restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 245     // Kill the helper
 246     GNUNET_OS_process_kill (helper_proc, SIGKILL);
 247     GNUNET_OS_process_wait (helper_proc);
 248     GNUNET_OS_process_close (helper_proc);
 249     helper_proc = NULL;
 250
 251     GNUNET_DISK_pipe_close(helper_in);
 252     GNUNET_DISK_pipe_close(helper_out);
 253
 254     /* Restart the helper */
 255     GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS, start_helper_and_schedule, NULL);
 256 }
 257
 258 /**
 259  * Read from the helper-process
 260  */
 261 static void
 262 helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 263     /* no message can be bigger then 64k */
 264     char buf[65535];
 265
 266     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 267       return;
 268
 269     int t = GNUNET_DISK_file_read(fh_from_helper, &buf, 65535);
 270
 271     /* On read-error, restart the helper */
 272     if (t<=0) {
 273         GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Read error for header from vpn-helper: %m\n");
 274         GNUNET_SCHEDULER_add_now(restart_helper, cls);
 275         return;
 276     }
 277
 278     /* FIXME */ GNUNET_SERVER_mst_receive(mst, NULL, buf, t, 0, 0);
 279
 280     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 281 }
 282
 283 /**
 284  * Calculate the checksum of an IPv4-Header
 285  */
 286 static uint16_t
 287 calculate_ip_checksum(uint16_t* hdr, short len) {
 288     uint32_t sum = 0;
 289     for(; len >= 2; len -= 2)
 290       sum += *(hdr++);
 291     if (len == 1)
 292       sum += *((unsigned char*)hdr);
 293
 294     sum = (sum >> 16) + (sum & 0xFFFF);
 295
 296     return ~sum;
 297 }
 298
 299 /**
 300  * Send an dns-answer-packet to the helper
 301  */
 302 static void
 303 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 304     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 305       return;
 306
 307     struct answer_packet_list* ans = answer_proc_head;
 308     size_t len = ntohs(ans->pkt.hdr.size);
 309
 310     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 311
 312     size_t data_len = len - sizeof(struct answer_packet) + 1;
 313     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 314     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 315
 316     struct ip_udp_dns* pkt = alloca(pkt_len);
 317     memset(pkt, 0, pkt_len);
 318
 319     /* set the gnunet-header */
 320     pkt->shdr.size = htons(pkt_len);
 321     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 322
 323     /* set the tun-header (no flags and ethertype of IPv4) */
 324     pkt->tun.flags = 0;
 325     pkt->tun.type = htons(0x0800);
 326
 327     /* set the ip-header */
 328     pkt->ip_hdr.version = 4;
 329     pkt->ip_hdr.hdr_lngth = 5;
 330     pkt->ip_hdr.diff_serv = 0;
 331     pkt->ip_hdr.tot_lngth = htons(net_len);
 332     pkt->ip_hdr.ident = 0;
 333     pkt->ip_hdr.flags = 0;
 334     pkt->ip_hdr.frag_off = 0;
 335     pkt->ip_hdr.ttl = 255;
 336     pkt->ip_hdr.proto = 0x11; /* UDP */
 337     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 338     pkt->ip_hdr.sadr = ans->pkt.from;
 339     pkt->ip_hdr.dadr = ans->pkt.to;
 340
 341     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 342
 343     /* set the udp-header */
 344     pkt->udp_dns.udp_hdr.spt = htons(53);
 345     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 346     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 347     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 348
 349     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 350
 351     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 352     GNUNET_free(ans);
 353
 354     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, pkt, pkt_len);
 355
 356     /* if more packets are available, reschedule */
 357     if (answer_proc_head != NULL)
 358       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 359                                        fh_to_helper,
 360                                        &helper_write,
 361                                        NULL);
 362 }
 363
 364 /**
 365  * @return GNUNET_YES if a mapping exists
 366  */
 367 static int
 368 address_mapping_exists(unsigned char addr[]) {
 369     GNUNET_HashCode* key = alloca(sizeof(GNUNET_HashCode));
 370     memset(key, 0, sizeof(GNUNET_HashCode));
 371     memcpy(key, addr, 16);
 372
 373     return GNUNET_CONTAINER_multihashmap_contains(hashmap, key);
 374 }
 375
 376 static void
 377 send_icmp_response(void* cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 378     struct ip6_icmp* request = cls;
 379
 380     struct ip6_icmp* response = alloca(ntohs(request->shdr.size));
 381     memset(response, 0, ntohs(request->shdr.size));
 382
 383     response->shdr.size = request->shdr.size;
 384     response->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 385
 386     response->tun.flags = 0;
 387     response->tun.type = htons(0x86dd);
 388
 389     response->ip6_hdr.hoplmt = 255;
 390     response->ip6_hdr.paylgth = request->ip6_hdr.paylgth;
 391     response->ip6_hdr.nxthdr = 0x3a;
 392     response->ip6_hdr.version = 6;
 393     memcpy(&response->ip6_hdr.sadr, &request->ip6_hdr.dadr, 16);
 394     memcpy(&response->ip6_hdr.dadr, &request->ip6_hdr.sadr, 16);
 395
 396     response->icmp_hdr.code = 0;
 397     response->icmp_hdr.type = 0x81;
 398
 399     /* Magic, more Magic! */
 400     response->icmp_hdr.chks = request->icmp_hdr.chks - 0x1;
 401
 402     /* Copy the rest of the packet */
 403     memcpy(response+1, request+1, ntohs(request->shdr.size) - sizeof(struct ip6_icmp));
 404
 405     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, response, ntohs(response->shdr.size));
 406
 407     GNUNET_free(request);
 408 }
 409
 410 /**
 411  * Receive packets from the helper-process
 412  */
 413 static void
 414 message_token(void *cls,
 415               void *client,
 416               const struct GNUNET_MessageHeader *message) {
 417     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 418
 419     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 420
 421     /* ethertype is ipv6 */
 422     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 423       {
 424         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 425         GNUNET_assert(pkt6->ip6_hdr.version == 6);
 426         struct ip6_tcp *pkt6_tcp;
 427         struct ip6_udp *pkt6_udp;
 428         struct ip6_icmp *pkt6_icmp;
 429
 430         pkt_printf(pkt6);
 431         switch(pkt6->ip6_hdr.nxthdr)
 432           {
 433           case 0x06:
 434             pkt6_tcp = (struct ip6_tcp*)pkt6;
 435             pkt_printf_ip6tcp(pkt6_tcp);
 436             break;
 437           case 0x11:
 438             pkt6_udp = (struct ip6_udp*)pkt6;
 439             pkt_printf_ip6udp(pkt6_udp);
 440             if (ntohs(pkt6_udp->udp_hdr.dpt) == 53) {
 441                 pkt_printf_ip6dns((struct ip6_udp_dns*)pkt6_udp);
 442             }
 443             break;
 444           case 0x3a:
 445             /* ICMPv6 */
 446             pkt6_icmp = (struct ip6_icmp*)pkt6;
 447             /* If this packet is an icmp-echo-request and a mapping exists, answer */
 448             if (pkt6_icmp->icmp_hdr.type == 0x80 && address_mapping_exists(pkt6->ip6_hdr.dadr))
 449               {
 450                 pkt6_icmp = GNUNET_malloc(ntohs(pkt6->shdr.size));
 451                 memcpy(pkt6_icmp, pkt6, ntohs(pkt6->shdr.size));
 452                 GNUNET_SCHEDULER_add_now(&send_icmp_response, pkt6_icmp);
 453               }
 454             break;
 455           }
 456       }
 457     /* ethertype is ipv4 */
 458     else if (ntohs(pkt_tun->tun.type) == 0x0800)
 459       {
 460         struct ip_pkt *pkt = (struct ip_pkt*) message;
 461         struct ip_udp *udp = (struct ip_udp*) message;
 462         GNUNET_assert(pkt->ip_hdr.version == 4);
 463
 464         /* Send dns-packets to the service-dns */
 465         if (pkt->ip_hdr.proto == 0x11 && ntohs(udp->udp_hdr.dpt) == 53 )
 466           {
 467             /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 468             size_t len = sizeof(struct query_packet) + ntohs(udp->udp_hdr.len) - 9;
 469
 470             struct query_packet_list* query = GNUNET_malloc(len + 2*sizeof(struct query_packet_list*));
 471             query->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 472             query->pkt.hdr.size = htons(len);
 473             query->pkt.orig_to = pkt->ip_hdr.dadr;
 474             query->pkt.orig_from = pkt->ip_hdr.sadr;
 475             query->pkt.src_port = udp->udp_hdr.spt;
 476             memcpy(query->pkt.data, udp->data, ntohs(udp->udp_hdr.len) - 8);
 477
 478             GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, query);
 479
 480             if (dns_connection != NULL)
 481               GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 482                                                   len,
 483                                                   GNUNET_TIME_UNIT_FOREVER_REL,
 484                                                   GNUNET_YES,
 485                                                   &send_query,
 486                                                   NULL);
 487           }
 488       }
 489 }
 490
 491 /**
 492  * Connect to the service-dns
 493  */
 494 static void
 495 connect_to_service_dns (void *cls,
 496                         const struct GNUNET_SCHEDULER_TaskContext *tc) {
 497     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 498       return;
 499     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Connecting to service-dns\n");
 500     GNUNET_assert (dns_connection == NULL);
 501     dns_connection = GNUNET_CLIENT_connect ("dns", cfg);
 502     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 503
 504     /* If a packet is already in the list, schedule to send it */
 505     if (head != NULL)
 506       GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 507                                           ntohs(head->pkt.hdr.size),
 508                                           GNUNET_TIME_UNIT_FOREVER_REL,
 509                                           GNUNET_YES,
 510                                           &send_query,
 511                                           NULL);
 512     else if (restart_hijack == 1)
 513       {
 514         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 515       }
 516 }
 517
 518 /**
 519  * Create a new Address from an answer-packet
 520  * {{{
 521  */
 522 void
 523 new_ip6addr(char* buf, struct answer_packet* pkt) {
 524         memcpy(buf, (int[]){htons(0x1234)}, 2);
 525         memcpy(buf+2, &pkt->service_descr.service_descriptor, 6);
 526         memcpy(buf+8, &pkt->service_descr.peer, 8);
 527 }
 528 /*}}}*/
 529
 530 /**
 531  * This gets scheduled with cls pointing to an answer_packet and does everything
 532  * needed in order to send it to the helper.
 533  *
 534  * At the moment this means "inventing" and IPv6-Address for .gnunet-services and
 535  * doing nothing for "real" services.
 536  */
 537 static void
 538 process_answer(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tc) {
 539     struct answer_packet* pkt = cls;
 540     struct answer_packet_list* list;
 541
 542     /* This answer is about a .gnunet-service
 543      *
 544      * It contains an almost complete DNS-Response, we have to fill in the ip
 545      * at the offset pkt->addroffset
 546      */
 547     //FIXME htons?
 548     if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_SERVICE)
 549       {
 550         pkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 551
 552         GNUNET_HashCode key;
 553         memset(&key, 0, sizeof(GNUNET_HashCode));
 554         new_ip6addr((char*)&key, pkt);
 555
 556         uint16_t namelen = strlen((char*)pkt->data+12)+1;
 557
 558         struct map_entry* value = GNUNET_malloc(sizeof(struct GNUNET_vpn_service_descriptor) + 2 + namelen);
 559
 560         value->namelen = namelen;
 561         memcpy(value->name, pkt->data+12, namelen);
 562
 563         memcpy(&value->desc, &pkt->service_descr, sizeof(struct GNUNET_vpn_service_descriptor));
 564
 565         if (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put(hashmap,
 566                                                            &key,
 567                                                            value,
 568                                                            GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
 569           {
 570             GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not store to hashmap\n");
 571           }
 572
 573         memcpy(((char*)pkt)+ntohs(pkt->addroffset), &key, 16);
 574
 575         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 576
 577         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 578
 579       }
 580     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_REV)
 581       {
 582         GNUNET_HashCode key;
 583         memset(&key, 0, sizeof key);
 584         unsigned char* k = (unsigned char*)&key;
 585         unsigned char* s = pkt->data+12;
 586         int i = 0;
 587         /* Whoever designed the reverse IPv6-lookup is batshit insane */
 588         for (i = 0; i < 16; i++)
 589           {
 590             unsigned char c1 = s[(4*i)+1];
 591             unsigned char c2 = s[(4*i)+3];
 592             if (c1 <= '9')
 593               k[15-i] = c1 - '0';
 594             else
 595               k[15-i] = c1 - 87; /* 87 is the difference between 'a' and 10 */
 596             if (c2 <= '9')
 597               k[15-i] += 16*(c2 - '0');
 598             else
 599               k[15-i] += 16*(c2 - 87);
 600           }
 601
 602         struct map_entry* map_entry = GNUNET_CONTAINER_multihashmap_get(hashmap, &key);
 603         unsigned short offset = ntohs(pkt->addroffset);
 604
 605         if (map_entry == NULL)
 606           {
 607             GNUNET_free(pkt);
 608             return;
 609           }
 610
 611         unsigned short namelen = htons(map_entry->namelen);
 612         char* name = map_entry->name;
 613
 614         list = GNUNET_malloc(2*sizeof(struct answer_packet_list*) + offset + 2 + ntohs(namelen));
 615
 616         struct answer_packet* rpkt = &list->pkt;
 617
 618         memcpy(rpkt, pkt, offset);
 619
 620         rpkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 621         rpkt->hdr.size = ntohs(offset + 2 + ntohs(namelen));
 622
 623         memcpy(((char*)rpkt)+offset, &namelen, 2);
 624         memcpy(((char*)rpkt)+offset+2, name, ntohs(namelen));
 625
 626       }
 627     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_IP)
 628       {
 629         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 630         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 631       }
 632     else
 633       {
 634         GNUNET_break(0);
 635         GNUNET_free(pkt);
 636         return;
 637       }
 638
 639     GNUNET_free(pkt);
 640
 641     GNUNET_CONTAINER_DLL_insert_after(answer_proc_head, answer_proc_tail, answer_proc_tail, list);
 642
 643     GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_to_helper, &helper_write, NULL);
 644
 645     return;
 646 }
 647
 648 /**
 649  * This receives packets from the service-dns and schedules process_answer to
 650  * handle it
 651  */
 652 static void
 653 dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg) {
 654     /* the service disconnected, reconnect after short wait */
 655     if (msg == NULL)
 656       {
 657         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 658         dns_connection = NULL;
 659         GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
 660                                       &connect_to_service_dns,
 661                                       NULL);
 662         return;
 663       }
 664
 665     /* the service did something strange, reconnect immediately */
 666     if (msg->type != htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS))
 667       {
 668         GNUNET_break (0);
 669         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 670         dns_connection = NULL;
 671         GNUNET_SCHEDULER_add_now (&connect_to_service_dns,
 672                                   NULL);
 673         return;
 674       }
 675     void *pkt = GNUNET_malloc(ntohs(msg->size));
 676
 677     memcpy(pkt, msg, ntohs(msg->size));
 678
 679     GNUNET_SCHEDULER_add_now(process_answer, pkt);
 680     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 681 }
 682
 683 /**
 684  * Main function that will be run by the scheduler.
 685  *
 686  * @param cls closure
 687  * @param args remaining command-line arguments
 688  * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 689  * @param cfg configuration
 690  */
 691 static void
 692 run (void *cls,
 693      char *const *args,
 694      const char *cfgfile,
 695      const struct GNUNET_CONFIGURATION_Handle *cfg_) {
 696     mst = GNUNET_SERVER_mst_create(&message_token, NULL);
 697     cfg = cfg_;
 698     restart_hijack = 0;
 699     hashmap = GNUNET_CONTAINER_multihashmap_create(65536);
 700     GNUNET_SCHEDULER_add_now (connect_to_service_dns, NULL);
 701     GNUNET_SCHEDULER_add_now (start_helper_and_schedule, NULL);
 702     GNUNET_SCHEDULER_add_delayed(GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls);
 703 }
 704
 705 /**
 706  * The main function to obtain template from gnunetd.
 707  *
 708  * @param argc number of arguments from the command line
 709  * @param argv command line arguments
 710  * @return 0 ok, 1 on error
 711  */
 712 int
 713 main (int argc, char *const *argv) {
 714     static const struct GNUNET_GETOPT_CommandLineOption options[] = {
 715         GNUNET_GETOPT_OPTION_END
 716     };
 717
 718     return (GNUNET_OK ==
 719             GNUNET_PROGRAM_run (argc,
 720                                 argv,
 721                                 "gnunet-daemon-vpn",
 722                                 gettext_noop ("help text"),
 723                                 options, &run, NULL)) ? ret : 1;
 724 }
 725
 726 /* end of gnunet-daemon-vpn.c */