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  */
 139 static size_t
 140 send_query(void* cls, size_t size, void* buf) {
 141     size_t len;
 142     /*
 143      * Send the rehijack-message
 144      */
 145     if (restart_hijack == 1)
 146       {
 147         restart_hijack = 0;
 148         /*
 149          * The message is just a header
 150          */
 151         GNUNET_assert(sizeof(struct GNUNET_MessageHeader) <= size);
 152         struct GNUNET_MessageHeader* hdr = buf;
 153         len = sizeof(struct GNUNET_MessageHeader);
 154         hdr->size = htons(len);
 155         hdr->type = htons(GNUNET_MESSAGE_TYPE_REHIJACK);
 156       }
 157     else
 158       {
 159         struct query_packet_list* query = head;
 160         len = ntohs(query->pkt.hdr.size);
 161
 162         GNUNET_assert(len <= size);
 163
 164         memcpy(buf, &query->pkt.hdr, len);
 165
 166         GNUNET_CONTAINER_DLL_remove (head, tail, query);
 167
 168         GNUNET_free(query);
 169       }
 170
 171     /*
 172      * Check whether more data is to be sent
 173      */
 174     if (head != NULL)
 175       {
 176         GNUNET_CLIENT_notify_transmit_ready(dns_connection, ntohs(head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 177       }
 178     else if (restart_hijack == 1)
 179       {
 180         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 181       }
 182
 183     return len;
 184 }
 185 /* }}} */
 186
 187 /**
 188  * Function scheduled as very last function, cleans up after us
 189  *{{{
 190  */
 191 static void
 192 cleanup(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 193     GNUNET_assert (0 != (tskctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN));
 194
 195     /* stop the helper */
 196     if (helper_proc != NULL)
 197       {
 198         GNUNET_OS_process_kill (helper_proc, SIGTERM);
 199         GNUNET_OS_process_wait (helper_proc);
 200         GNUNET_OS_process_close (helper_proc);
 201         helper_proc = NULL;
 202       }
 203
 204     /* close the connection to the service-dns */
 205     if (dns_connection != NULL)
 206       {
 207         GNUNET_CLIENT_disconnect (dns_connection, GNUNET_NO);
 208         dns_connection = NULL;
 209       }
 210 }
 211 /*}}}*/
 212
 213 /**
 214  * Start the helper-process
 215  * {{{
 216  */
 217 static void
 218 start_helper_and_schedule(void *cls,
 219                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
 220     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 221       return;
 222
 223     helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO);
 224     helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_NO, GNUNET_YES);
 225
 226     if (helper_in == NULL || helper_out == NULL) return;
 227
 228     helper_proc = GNUNET_OS_start_process(helper_in, helper_out, "gnunet-helper-vpn", "gnunet-helper-vpn", NULL);
 229
 230     fh_from_helper = GNUNET_DISK_pipe_handle (helper_out, GNUNET_DISK_PIPE_END_READ);
 231     fh_to_helper = GNUNET_DISK_pipe_handle (helper_in, GNUNET_DISK_PIPE_END_WRITE);
 232
 233     GNUNET_DISK_pipe_close_end(helper_out, GNUNET_DISK_PIPE_END_WRITE);
 234     GNUNET_DISK_pipe_close_end(helper_in, GNUNET_DISK_PIPE_END_READ);
 235
 236     /* Tell the dns-service to rehijack the dns-port
 237      * The routing-table gets flushed if an interface disappears.
 238      */
 239     restart_hijack = 1;
 240     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 241
 242     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 243 }
 244 /*}}}*/
 245
 246 /**
 247  * Restart the helper-process
 248  * {{{
 249  */
 250 static void
 251 restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 252     // Kill the helper
 253     GNUNET_OS_process_kill (helper_proc, SIGKILL);
 254     GNUNET_OS_process_wait (helper_proc);
 255     GNUNET_OS_process_close (helper_proc);
 256     helper_proc = NULL;
 257
 258     GNUNET_DISK_pipe_close(helper_in);
 259     GNUNET_DISK_pipe_close(helper_out);
 260
 261     /* Restart the helper */
 262     GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS, start_helper_and_schedule, NULL);
 263 }
 264 /*}}}*/
 265
 266 /**
 267  * Read from the helper-process
 268  * {{{
 269  */
 270 static void
 271 helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 272     /* no message can be bigger then 64k */
 273     char buf[65535];
 274
 275     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 276       return;
 277
 278     int t = GNUNET_DISK_file_read(fh_from_helper, &buf, 65535);
 279
 280     /* On read-error, restart the helper */
 281     if (t<=0) {
 282         GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Read error for header from vpn-helper: %m\n");
 283         GNUNET_SCHEDULER_add_now(restart_helper, cls);
 284         return;
 285     }
 286
 287     /* FIXME */ GNUNET_SERVER_mst_receive(mst, NULL, buf, t, 0, 0);
 288
 289     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 290 }
 291 /*}}}*/
 292
 293 /**
 294  * Calculate the checksum of an IPv4-Header
 295  */
 296 static uint16_t
 297 calculate_ip_checksum(uint16_t* hdr, short len) {
 298     uint32_t sum = 0;
 299     for(; len >= 2; len -= 2)
 300       sum += *(hdr++);
 301     if (len == 1)
 302       sum += *((unsigned char*)hdr);
 303
 304     sum = (sum >> 16) + (sum & 0xFFFF);
 305
 306     return ~sum;
 307 }
 308
 309 /**
 310  * Send an dns-answer-packet to the helper
 311  */
 312 static void
 313 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 314     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 315       return;
 316
 317     struct answer_packet_list* ans = answer_proc_head;
 318     size_t len = ntohs(ans->pkt.hdr.size);
 319
 320     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 321
 322     GNUNET_assert (20 == sizeof (struct ip_hdr));
 323     GNUNET_assert (8 == sizeof (struct udp_pkt));
 324     size_t data_len = len - sizeof(struct answer_packet) + 1;
 325     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 326     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 327
 328     struct ip_udp_dns* pkt = alloca(pkt_len);
 329     memset(pkt, 0, pkt_len);
 330
 331     /* set the gnunet-header */
 332     pkt->shdr.size = htons(pkt_len);
 333     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 334
 335     /* set the tun-header (no flags and ethertype of IPv4) */
 336     pkt->tun.flags = 0;
 337     pkt->tun.type = htons(0x0800);
 338
 339     /* set the ip-header */
 340     pkt->ip_hdr.version = 4;
 341     pkt->ip_hdr.hdr_lngth = 5;
 342     pkt->ip_hdr.diff_serv = 0;
 343     pkt->ip_hdr.tot_lngth = htons(net_len);
 344     pkt->ip_hdr.ident = 0;
 345     pkt->ip_hdr.flags = 0;
 346     pkt->ip_hdr.frag_off = 0;
 347     pkt->ip_hdr.ttl = 255;
 348     pkt->ip_hdr.proto = 0x11; /* UDP */
 349     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 350     pkt->ip_hdr.sadr = ans->pkt.from;
 351     pkt->ip_hdr.dadr = ans->pkt.to;
 352
 353     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 354
 355     /* set the udp-header */
 356     pkt->udp_dns.udp_hdr.spt = htons(53);
 357     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 358     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 359     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 360
 361     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 362
 363     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 364     GNUNET_free(ans);
 365
 366     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, pkt, pkt_len);
 367
 368     /* if more packets are available, reschedule */
 369     if (answer_proc_head != NULL)
 370       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 371                                        fh_to_helper,
 372                                        &helper_write,
 373                                        NULL);
 374 }
 375
 376 /**
 377  * @return GNUNET_YES if a mapping exists
 378  */
 379 static int
 380 address_mapping_exists(unsigned char addr[]) {
 381     GNUNET_HashCode* key = alloca(sizeof(GNUNET_HashCode));
 382     unsigned char* k = (unsigned char*)key;
 383     memset(key, 0, sizeof(GNUNET_HashCode));
 384     unsigned int i;
 385     for (i = 0; i < 16; i++)
 386         k[15-i] = addr[i];
 387
 388     return GNUNET_CONTAINER_multihashmap_contains(hashmap, key);
 389 }
 390
 391 static void
 392 send_icmp_response(void* cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 393     struct ip6_icmp* request = cls;
 394
 395     struct ip6_icmp* response = alloca(ntohs(request->shdr.size));
 396     memset(response, 0, ntohs(request->shdr.size));
 397
 398     response->shdr.size = request->shdr.size;
 399     response->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 400
 401     response->tun.flags = 0;
 402     response->tun.type = htons(0x86dd);
 403
 404     response->ip6_hdr.hoplmt = 255;
 405     response->ip6_hdr.paylgth = request->ip6_hdr.paylgth;
 406     response->ip6_hdr.nxthdr = 0x3a;
 407     response->ip6_hdr.version = 6;
 408     memcpy(&response->ip6_hdr.sadr, &request->ip6_hdr.dadr, 16);
 409     memcpy(&response->ip6_hdr.dadr, &request->ip6_hdr.sadr, 16);
 410
 411     response->icmp_hdr.code = 0;
 412     response->icmp_hdr.type = 0x81;
 413
 414     /* Magic, more Magic! */
 415     response->icmp_hdr.chks = request->icmp_hdr.chks - 0x1;
 416
 417     /* Copy the rest of the packet */
 418     memcpy(response+1, request+1, ntohs(request->shdr.size) - sizeof(struct ip6_icmp));
 419
 420     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, response, ntohs(response->shdr.size));
 421
 422     GNUNET_free(request);
 423 }
 424
 425 /**
 426  * Receive packets from the helper-process
 427  */
 428 static void
 429 message_token(void *cls,
 430               void *client,
 431               const struct GNUNET_MessageHeader *message) {
 432     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 433
 434     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 435
 436     /* ethertype is ipv6 */
 437     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 438       {
 439         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 440         GNUNET_assert(pkt6->ip6_hdr.version == 6);
 441         struct ip6_tcp *pkt6_tcp;
 442         struct ip6_udp *pkt6_udp;
 443         struct ip6_icmp *pkt6_icmp;
 444
 445         pkt_printf(pkt6);
 446         switch(pkt6->ip6_hdr.nxthdr)
 447           {
 448           case 0x06:
 449             pkt6_tcp = (struct ip6_tcp*)pkt6;
 450             pkt_printf_ip6tcp(pkt6_tcp);
 451             break;
 452           case 0x11:
 453             pkt6_udp = (struct ip6_udp*)pkt6;
 454             pkt_printf_ip6udp(pkt6_udp);
 455             if (ntohs(pkt6_udp->udp_hdr.dpt) == 53) {
 456                 pkt_printf_ip6dns((struct ip6_udp_dns*)pkt6_udp);
 457             }
 458             break;
 459           case 0x3a:
 460             /* ICMPv6 */
 461             pkt6_icmp = (struct ip6_icmp*)pkt6;
 462             /* If this packet is an icmp-echo-request and a mapping exists, answer */
 463             if (pkt6_icmp->icmp_hdr.type == 0x80 && address_mapping_exists(pkt6->ip6_hdr.dadr))
 464               {
 465                 pkt6_icmp = GNUNET_malloc(ntohs(pkt6->shdr.size));
 466                 memcpy(pkt6_icmp, pkt6, ntohs(pkt6->shdr.size));
 467                 GNUNET_SCHEDULER_add_now(&send_icmp_response, pkt6_icmp);
 468               }
 469             break;
 470           }
 471       }
 472     /* ethertype is ipv4 */
 473     else if (ntohs(pkt_tun->tun.type) == 0x0800)
 474       {
 475         struct ip_pkt *pkt = (struct ip_pkt*) message;
 476         struct ip_udp *udp = (struct ip_udp*) message;
 477         GNUNET_assert(pkt->ip_hdr.version == 4);
 478
 479         /* Send dns-packets to the service-dns */
 480         if (pkt->ip_hdr.proto == 0x11 && ntohs(udp->udp_hdr.dpt) == 53 )
 481           {
 482             /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 483             size_t len = sizeof(struct query_packet) + ntohs(udp->udp_hdr.len) - 9;
 484
 485             struct query_packet_list* query = GNUNET_malloc(len + 2*sizeof(struct query_packet_list*));
 486             query->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 487             query->pkt.hdr.size = htons(len);
 488             query->pkt.orig_to = pkt->ip_hdr.dadr;
 489             query->pkt.orig_from = pkt->ip_hdr.sadr;
 490             query->pkt.src_port = udp->udp_hdr.spt;
 491             memcpy(query->pkt.data, udp->data, ntohs(udp->udp_hdr.len) - 8);
 492
 493             GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, query);
 494
 495             if (dns_connection != NULL)
 496               GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 497                                                   len,
 498                                                   GNUNET_TIME_UNIT_FOREVER_REL,
 499                                                   GNUNET_YES,
 500                                                   &send_query,
 501                                                   NULL);
 502           }
 503       }
 504 }
 505
 506 /**
 507  * Connect to the service-dns
 508  */
 509 static void
 510 connect_to_service_dns (void *cls,
 511                         const struct GNUNET_SCHEDULER_TaskContext *tc) {
 512     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 513       return;
 514     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Connecting to service-dns\n");
 515     GNUNET_assert (dns_connection == NULL);
 516     dns_connection = GNUNET_CLIENT_connect ("dns", cfg);
 517     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 518
 519     /* If a packet is already in the list, schedule to send it */
 520     if (head != NULL)
 521       GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 522                                           ntohs(head->pkt.hdr.size),
 523                                           GNUNET_TIME_UNIT_FOREVER_REL,
 524                                           GNUNET_YES,
 525                                           &send_query,
 526                                           NULL);
 527     else if (restart_hijack == 1)
 528       {
 529         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 530       }
 531 }
 532
 533 /**
 534  * Create a new Address from an answer-packet
 535  * {{{
 536  */
 537 void
 538 new_ip6addr(char* buf, struct answer_packet* pkt) {
 539         memcpy(buf+14, (int[]){htons(0x3412)}, 2);
 540         memcpy(buf+8, &pkt->service_descr.service_descriptor, 6);
 541         memcpy(buf, &pkt->service_descr.peer, 8);
 542 }
 543 /*}}}*/
 544
 545 /**
 546  * This gets scheduled with cls pointing to an answer_packet and does everything
 547  * needed in order to send it to the helper.
 548  *
 549  * At the moment this means "inventing" and IPv6-Address for .gnunet-services and
 550  * doing nothing for "real" services.
 551  */
 552 static void
 553 process_answer(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tc) {
 554     struct answer_packet* pkt = cls;
 555     struct answer_packet_list* list;
 556
 557     /* This answer is about a .gnunet-service
 558      *
 559      * It contains an almost complete DNS-Response, we have to fill in the ip
 560      * at the offset pkt->addroffset
 561      */
 562     //FIXME htons?
 563     if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_SERVICE)
 564       {
 565         pkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 566
 567         GNUNET_HashCode key;
 568         memset(&key, 0, sizeof(GNUNET_HashCode));
 569         new_ip6addr((char*)&key, pkt);
 570
 571         uint16_t namelen = strlen((char*)pkt->data+12)+1;
 572
 573         struct map_entry* value = GNUNET_malloc(sizeof(struct GNUNET_vpn_service_descriptor) + 2 + namelen);
 574
 575         value->namelen = namelen;
 576         memcpy(value->name, pkt->data+12, namelen);
 577
 578         memcpy(&value->desc, &pkt->service_descr, sizeof(struct GNUNET_vpn_service_descriptor));
 579
 580         if (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put(hashmap,
 581                                                            &key,
 582                                                            value,
 583                                                            GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
 584           {
 585             GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not store to hashmap\n");
 586           }
 587
 588         /*
 589          * Copy the newly generated backward ip-address to the packet
 590          */
 591         char* c = ((char*)pkt)+ntohs(pkt->addroffset);
 592         char* k = (char*)&key;
 593         unsigned int i;
 594         for (i = 0; i < 16; i++)
 595             c[15-i] = k[i];
 596
 597         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 598
 599         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 600
 601       }
 602     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_REV)
 603       {
 604         GNUNET_HashCode key;
 605         memset(&key, 0, sizeof key);
 606         unsigned char* k = (unsigned char*)&key;
 607         unsigned char* s = pkt->data+12;
 608         int i = 0;
 609         /* Whoever designed the reverse IPv6-lookup is batshit insane */
 610         for (i = 0; i < 16; i++)
 611           {
 612             unsigned char c1 = s[(4*i)+1];
 613             unsigned char c2 = s[(4*i)+3];
 614             if (c1 <= '9')
 615               k[i] = c1 - '0';
 616             else
 617               k[i] = c1 - 87; /* 87 is the difference between 'a' and 10 */
 618             if (c2 <= '9')
 619               k[i] += 16*(c2 - '0');
 620             else
 621               k[i] += 16*(c2 - 87);
 622           }
 623
 624         struct map_entry* map_entry = GNUNET_CONTAINER_multihashmap_get(hashmap, &key);
 625         unsigned short offset = ntohs(pkt->addroffset);
 626
 627         if (map_entry == NULL)
 628           {
 629             GNUNET_free(pkt);
 630             return;
 631           }
 632
 633         unsigned short namelen = htons(map_entry->namelen);
 634         char* name = map_entry->name;
 635
 636         list = GNUNET_malloc(2*sizeof(struct answer_packet_list*) + offset + 2 + ntohs(namelen));
 637
 638         struct answer_packet* rpkt = &list->pkt;
 639
 640         memcpy(rpkt, pkt, offset);
 641
 642         rpkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 643         rpkt->hdr.size = ntohs(offset + 2 + ntohs(namelen));
 644
 645         memcpy(((char*)rpkt)+offset, &namelen, 2);
 646         memcpy(((char*)rpkt)+offset+2, name, ntohs(namelen));
 647
 648       }
 649     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_IP)
 650       {
 651         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 652         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 653       }
 654     else
 655       {
 656         GNUNET_break(0);
 657         GNUNET_free(pkt);
 658         return;
 659       }
 660
 661     GNUNET_free(pkt);
 662
 663     GNUNET_CONTAINER_DLL_insert_after(answer_proc_head, answer_proc_tail, answer_proc_tail, list);
 664
 665     GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_to_helper, &helper_write, NULL);
 666
 667     return;
 668 }
 669
 670 /**
 671  * This receives packets from the service-dns and schedules process_answer to
 672  * handle it
 673  */
 674 static void
 675 dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg) {
 676     /* the service disconnected, reconnect after short wait */
 677     if (msg == NULL)
 678       {
 679         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 680         dns_connection = NULL;
 681         GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
 682                                       &connect_to_service_dns,
 683                                       NULL);
 684         return;
 685       }
 686
 687     /* the service did something strange, reconnect immediately */
 688     if (msg->type != htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS))
 689       {
 690         GNUNET_break (0);
 691         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 692         dns_connection = NULL;
 693         GNUNET_SCHEDULER_add_now (&connect_to_service_dns,
 694                                   NULL);
 695         return;
 696       }
 697     void *pkt = GNUNET_malloc(ntohs(msg->size));
 698
 699     memcpy(pkt, msg, ntohs(msg->size));
 700
 701     GNUNET_SCHEDULER_add_now(process_answer, pkt);
 702     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 703 }
 704
 705 /**
 706  * Main function that will be run by the scheduler.
 707  *
 708  * @param cls closure
 709  * @param args remaining command-line arguments
 710  * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 711  * @param cfg configuration
 712  */
 713 static void
 714 run (void *cls,
 715      char *const *args,
 716      const char *cfgfile,
 717      const struct GNUNET_CONFIGURATION_Handle *cfg_) {
 718     mst = GNUNET_SERVER_mst_create(&message_token, NULL);
 719     cfg = cfg_;
 720     restart_hijack = 0;
 721     hashmap = GNUNET_CONTAINER_multihashmap_create(65536);
 722     GNUNET_SCHEDULER_add_now (connect_to_service_dns, NULL);
 723     GNUNET_SCHEDULER_add_now (start_helper_and_schedule, NULL);
 724     GNUNET_SCHEDULER_add_delayed(GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls);
 725 }
 726
 727 /**
 728  * The main function to obtain template from gnunetd.
 729  *
 730  * @param argc number of arguments from the command line
 731  * @param argv command line arguments
 732  * @return 0 ok, 1 on error
 733  */
 734 int
 735 main (int argc, char *const *argv) {
 736     static const struct GNUNET_GETOPT_CommandLineOption options[] = {
 737         GNUNET_GETOPT_OPTION_END
 738     };
 739
 740     return (GNUNET_OK ==
 741             GNUNET_PROGRAM_run (argc,
 742                                 argv,
 743                                 "gnunet-daemon-vpn",
 744                                 gettext_noop ("help text"),
 745                                 options, &run, NULL)) ? ret : 1;
 746 }
 747
 748 /* end of gnunet-daemon-vpn.c */