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 static void helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx);
 118 static void dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg);
 119
 120 /**
 121  * Callback called by notify_transmit_ready; sends dns-queries or rehijack-messages
 122  * to the service-dns
 123  */
 124 static size_t
 125 send_query(void* cls, size_t size, void* buf) {
 126     size_t len;
 127     /*
 128      * Send the rehijack-message
 129      */
 130     if (restart_hijack == 1)
 131       {
 132         restart_hijack = 0;
 133         /*
 134          * The message is just a header
 135          */
 136         GNUNET_assert(sizeof(struct GNUNET_MessageHeader) <= size);
 137         struct GNUNET_MessageHeader* hdr = buf;
 138         len = sizeof(struct GNUNET_MessageHeader);
 139         hdr->size = htons(len);
 140         hdr->type = htons(GNUNET_MESSAGE_TYPE_REHIJACK);
 141       }
 142     else
 143       {
 144         struct query_packet_list* query = head;
 145         len = ntohs(query->pkt.hdr.size);
 146
 147         GNUNET_assert(len <= size);
 148
 149         memcpy(buf, &query->pkt.hdr, len);
 150
 151         GNUNET_CONTAINER_DLL_remove (head, tail, query);
 152
 153         GNUNET_free(query);
 154       }
 155
 156     /*
 157      * Check whether more data is to be sent
 158      */
 159     if (head != NULL)
 160       {
 161         GNUNET_CLIENT_notify_transmit_ready(dns_connection, ntohs(head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 162       }
 163     else if (restart_hijack == 1)
 164       {
 165         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 166       }
 167
 168     return len;
 169 }
 170
 171 /**
 172  * Function scheduled as very last function, cleans up after us
 173  */
 174 static void
 175 cleanup(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 176     GNUNET_assert (0 != (tskctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN));
 177
 178     /* stop the helper */
 179     if (helper_proc != NULL)
 180       {
 181         GNUNET_OS_process_kill (helper_proc, SIGTERM);
 182         GNUNET_OS_process_wait (helper_proc);
 183         GNUNET_OS_process_close (helper_proc);
 184         helper_proc = NULL;
 185       }
 186
 187     /* close the connection to the service-dns */
 188     if (dns_connection != NULL)
 189       {
 190         GNUNET_CLIENT_disconnect (dns_connection, GNUNET_NO);
 191         dns_connection = NULL;
 192       }
 193 }
 194
 195 /**
 196  * Start the helper-process
 197  */
 198 static void
 199 start_helper_and_schedule(void *cls,
 200                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
 201     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 202       return;
 203
 204     helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO);
 205     helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_NO, GNUNET_YES);
 206
 207     if (helper_in == NULL || helper_out == NULL) return;
 208
 209     helper_proc = GNUNET_OS_start_process(helper_in, helper_out, "gnunet-helper-vpn", "gnunet-helper-vpn", NULL);
 210
 211     fh_from_helper = GNUNET_DISK_pipe_handle (helper_out, GNUNET_DISK_PIPE_END_READ);
 212     fh_to_helper = GNUNET_DISK_pipe_handle (helper_in, GNUNET_DISK_PIPE_END_WRITE);
 213
 214     GNUNET_DISK_pipe_close_end(helper_out, GNUNET_DISK_PIPE_END_WRITE);
 215     GNUNET_DISK_pipe_close_end(helper_in, GNUNET_DISK_PIPE_END_READ);
 216
 217     /* Tell the dns-service to rehijack the dns-port
 218      * The routing-table gets flushed if an interface disappears.
 219      */
 220     restart_hijack = 1;
 221     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 222
 223     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 224 }
 225
 226 /**
 227  * Restart the helper-process
 228  */
 229 static void
 230 restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 231     // Kill the helper
 232     GNUNET_OS_process_kill (helper_proc, SIGKILL);
 233     GNUNET_OS_process_wait (helper_proc);
 234     GNUNET_OS_process_close (helper_proc);
 235     helper_proc = NULL;
 236
 237     GNUNET_DISK_pipe_close(helper_in);
 238     GNUNET_DISK_pipe_close(helper_out);
 239
 240     /* Restart the helper */
 241     GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS, start_helper_and_schedule, NULL);
 242 }
 243
 244 /**
 245  * Read from the helper-process
 246  */
 247 static void
 248 helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 249     /* no message can be bigger then 64k */
 250     char buf[65535];
 251
 252     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 253       return;
 254
 255     int t = GNUNET_DISK_file_read(fh_from_helper, &buf, 65535);
 256
 257     /* On read-error, restart the helper */
 258     if (t<=0) {
 259         GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Read error for header from vpn-helper: %m\n");
 260         GNUNET_SCHEDULER_add_now(restart_helper, cls);
 261         return;
 262     }
 263
 264     /* FIXME */ GNUNET_SERVER_mst_receive(mst, NULL, buf, t, 0, 0);
 265
 266     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 267 }
 268
 269 /**
 270  * Calculate the checksum of an IPv4-Header
 271  */
 272 static uint16_t
 273 calculate_ip_checksum(uint16_t* hdr, short len) {
 274     uint32_t sum = 0;
 275     for(; len >= 2; len -= 2)
 276       sum += *(hdr++);
 277     if (len == 1)
 278       sum += *((unsigned char*)hdr);
 279
 280     sum = (sum >> 16) + (sum & 0xFFFF);
 281
 282     return ~sum;
 283 }
 284
 285 /**
 286  * Send an dns-answer-packet to the helper
 287  */
 288 static void
 289 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 290     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 291       return;
 292
 293     struct answer_packet_list* ans = answer_proc_head;
 294     size_t len = ntohs(ans->pkt.hdr.size);
 295
 296     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 297
 298     size_t data_len = len - sizeof(struct answer_packet) + 1;
 299     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 300     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 301
 302     struct ip_udp_dns* pkt = alloca(pkt_len);
 303     memset(pkt, 0, pkt_len);
 304
 305     /* set the gnunet-header */
 306     pkt->shdr.size = htons(pkt_len);
 307     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 308
 309     /* set the tun-header (no flags and ethertype of IPv4) */
 310     pkt->tun.flags = 0;
 311     pkt->tun.type = htons(0x0800);
 312
 313     /* set the ip-header */
 314     pkt->ip_hdr.version = 4;
 315     pkt->ip_hdr.hdr_lngth = 5;
 316     pkt->ip_hdr.diff_serv = 0;
 317     pkt->ip_hdr.tot_lngth = htons(net_len);
 318     pkt->ip_hdr.ident = 0;
 319     pkt->ip_hdr.flags = 0;
 320     pkt->ip_hdr.frag_off = 0;
 321     pkt->ip_hdr.ttl = 255;
 322     pkt->ip_hdr.proto = 0x11; /* UDP */
 323     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 324     pkt->ip_hdr.sadr = ans->pkt.from;
 325     pkt->ip_hdr.dadr = ans->pkt.to;
 326
 327     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 328
 329     /* set the udp-header */
 330     pkt->udp_dns.udp_hdr.spt = htons(53);
 331     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 332     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 333     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 334
 335     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 336
 337     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 338     GNUNET_free(ans);
 339
 340     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, pkt, pkt_len);
 341
 342     /* if more packets are available, reschedule */
 343     if (answer_proc_head != NULL)
 344       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 345                                        fh_to_helper,
 346                                        &helper_write,
 347                                        NULL);
 348 }
 349
 350 static int
 351 address_mapping_exists(unsigned char addr[]) {
 352     return 1;
 353 }
 354
 355 static void
 356 send_icmp_response(void* cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 357     struct ip6_icmp* request = cls;
 358
 359     struct ip6_icmp* response = alloca(ntohs(request->shdr.size));
 360     memset(response, 0, ntohs(request->shdr.size));
 361
 362     response->shdr.size = request->shdr.size;
 363     response->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 364
 365     response->tun.flags = 0;
 366     response->tun.type = htons(0x86dd);
 367
 368     response->ip6_hdr.hoplmt = 255;
 369     response->ip6_hdr.paylgth = request->ip6_hdr.paylgth;
 370     response->ip6_hdr.nxthdr = 0x3a;
 371     response->ip6_hdr.version = 6;
 372     memcpy(&response->ip6_hdr.sadr, &request->ip6_hdr.dadr, 16);
 373     memcpy(&response->ip6_hdr.dadr, &request->ip6_hdr.sadr, 16);
 374
 375     response->icmp_hdr.code = 0;
 376     response->icmp_hdr.type = 0x81;
 377
 378     /* Magic, more Magic! */
 379     response->icmp_hdr.chks = request->icmp_hdr.chks - 0x1;
 380
 381     /* Copy the rest of the packet */
 382     memcpy(response+1, request+1, ntohs(request->shdr.size) - sizeof(struct ip6_icmp));
 383
 384     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, response, ntohs(response->shdr.size));
 385
 386     GNUNET_free(request);
 387 }
 388
 389 /**
 390  * Receive packets from the helper-process
 391  */
 392 static void
 393 message_token(void *cls,
 394               void *client,
 395               const struct GNUNET_MessageHeader *message) {
 396     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 397
 398     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 399
 400     /* ethertype is ipv6 */
 401     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 402       {
 403         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 404         GNUNET_assert(pkt6->ip6_hdr.version == 6);
 405         struct ip6_tcp *pkt6_tcp;
 406         struct ip6_udp *pkt6_udp;
 407         struct ip6_icmp *pkt6_icmp;
 408
 409         pkt_printf(pkt6);
 410         switch(pkt6->ip6_hdr.nxthdr)
 411           {
 412           case 0x06:
 413             pkt6_tcp = (struct ip6_tcp*)pkt6;
 414             pkt_printf_ip6tcp(pkt6_tcp);
 415             break;
 416           case 0x11:
 417             pkt6_udp = (struct ip6_udp*)pkt6;
 418             pkt_printf_ip6udp(pkt6_udp);
 419             if (ntohs(pkt6_udp->udp_hdr.dpt) == 53) {
 420                 pkt_printf_ip6dns((struct ip6_udp_dns*)pkt6_udp);
 421             }
 422             break;
 423           case 0x3a:
 424             /* ICMPv6 */
 425             pkt6_icmp = GNUNET_malloc(ntohs(pkt6->shdr.size));
 426             memcpy(pkt6_icmp, pkt6, ntohs(pkt6->shdr.size));
 427             /* If this packet is an icmp-echo-request and a mapping exists, answer */
 428             if (pkt6_icmp->icmp_hdr.type == 0x80 && address_mapping_exists(pkt6->ip6_hdr.sadr))
 429                 GNUNET_SCHEDULER_add_now(&send_icmp_response, pkt6_icmp);
 430             break;
 431           }
 432       }
 433     /* ethertype is ipv4 */
 434     else if (ntohs(pkt_tun->tun.type) == 0x0800)
 435       {
 436         struct ip_pkt *pkt = (struct ip_pkt*) message;
 437         struct ip_udp *udp = (struct ip_udp*) message;
 438         GNUNET_assert(pkt->ip_hdr.version == 4);
 439
 440         /* Send dns-packets to the service-dns */
 441         if (pkt->ip_hdr.proto == 0x11 && ntohs(udp->udp_hdr.dpt) == 53 )
 442           {
 443             /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 444             size_t len = sizeof(struct query_packet) + ntohs(udp->udp_hdr.len) - 9;
 445
 446             struct query_packet_list* query = GNUNET_malloc(len + 2*sizeof(struct query_packet_list*));
 447             query->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 448             query->pkt.hdr.size = htons(len);
 449             query->pkt.orig_to = pkt->ip_hdr.dadr;
 450             query->pkt.orig_from = pkt->ip_hdr.sadr;
 451             query->pkt.src_port = udp->udp_hdr.spt;
 452             memcpy(query->pkt.data, udp->data, ntohs(udp->udp_hdr.len) - 8);
 453
 454             GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, query);
 455
 456             if (dns_connection != NULL)
 457               GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 458                                                   len,
 459                                                   GNUNET_TIME_UNIT_FOREVER_REL,
 460                                                   GNUNET_YES,
 461                                                   &send_query,
 462                                                   NULL);
 463           }
 464       }
 465 }
 466
 467 /**
 468  * Connect to the service-dns
 469  */
 470 static void
 471 connect_to_service_dns (void *cls,
 472                         const struct GNUNET_SCHEDULER_TaskContext *tc) {
 473     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 474       return;
 475     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Connecting to service-dns\n");
 476     GNUNET_assert (dns_connection == NULL);
 477     dns_connection = GNUNET_CLIENT_connect ("dns", cfg);
 478     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 479
 480     /* If a packet is already in the list, schedule to send it */
 481     if (head != NULL)
 482       GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 483                                           ntohs(head->pkt.hdr.size),
 484                                           GNUNET_TIME_UNIT_FOREVER_REL,
 485                                           GNUNET_YES,
 486                                           &send_query,
 487                                           NULL);
 488     else if (restart_hijack == 1)
 489       {
 490         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 491       }
 492 }
 493
 494 /**
 495  * This gets scheduled with cls pointing to an answer_packet and does everything
 496  * needed in order to send it to the helper.
 497  *
 498  * At the moment this means "inventing" and IPv6-Address for .gnunet-services and
 499  * doing nothing for "real" services.
 500  */
 501 static void
 502 process_answer(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tc) {
 503     struct answer_packet* pkt = cls;
 504     struct answer_packet_list* list;
 505
 506     /* This answer is about a .gnunet-service
 507      *
 508      * It contains an almost complete DNS-Response, we have to fill in the ip
 509      * at the offset pkt->addroffset
 510      */
 511     //FIXME htons?
 512     if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_SERVICE)
 513       {
 514         unsigned char ip6addr[16];
 515
 516         pkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 517         memcpy(ip6addr, (int[]){htons(0x1234)}, 2);
 518         memcpy(ip6addr+2, &pkt->peer, 7);
 519         memcpy(ip6addr+9, &pkt->service_descriptor, 7);
 520
 521         memcpy(((char*)pkt)+ntohs(pkt->addroffset), ip6addr, 16);
 522
 523           /*FIXME:
 524            * -save DNS_Record into hashmap, pointed to by ip
 525            * -regularily walk through hashmap, deleting old entries
 526            *  when is an entry old?
 527            *  have a last-used field
 528            *  don't remove if last-used "recent", ask dht again if record expired
 529            */
 530
 531         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 532
 533         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 534       }
 535     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_REV)
 536       {
 537         unsigned short offset = ntohs(pkt->addroffset);
 538
 539         unsigned short namelen = htons(22); /* calculate the length of the answer */
 540         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};
 541
 542         list = GNUNET_malloc(2*sizeof(struct answer_packet_list*) + offset + 2 + ntohs(namelen));
 543
 544         struct answer_packet* rpkt = &list->pkt;
 545
 546         memcpy(rpkt, pkt, offset);
 547
 548         rpkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 549         rpkt->hdr.size = ntohs(offset + 2 + ntohs(namelen));
 550
 551         memcpy(((char*)rpkt)+offset, &namelen, 2);
 552         memcpy(((char*)rpkt)+offset+2, name, ntohs(namelen));
 553
 554       }
 555     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_IP)
 556       {
 557         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 558         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 559       }
 560     else
 561       {
 562         GNUNET_break(0);
 563         GNUNET_free(pkt);
 564         return;
 565       }
 566
 567     GNUNET_free(pkt);
 568
 569     GNUNET_CONTAINER_DLL_insert_after(answer_proc_head, answer_proc_tail, answer_proc_tail, list);
 570
 571     GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_to_helper, &helper_write, NULL);
 572
 573     return;
 574 }
 575
 576 /**
 577  * This receives packets from the service-dns and schedules process_answer to
 578  * handle it
 579  */
 580 static void
 581 dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg) {
 582     /* the service disconnected, reconnect after short wait */
 583     if (msg == NULL)
 584       {
 585         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 586         dns_connection = NULL;
 587         GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
 588                                       &connect_to_service_dns,
 589                                       NULL);
 590         return;
 591       }
 592
 593     /* the service did something strange, reconnect immediately */
 594     if (msg->type != htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS))
 595       {
 596         GNUNET_break (0);
 597         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 598         dns_connection = NULL;
 599         GNUNET_SCHEDULER_add_now (&connect_to_service_dns,
 600                                   NULL);
 601         return;
 602       }
 603     void *pkt = GNUNET_malloc(ntohs(msg->size));
 604
 605     memcpy(pkt, msg, ntohs(msg->size));
 606
 607     GNUNET_SCHEDULER_add_now(process_answer, pkt);
 608     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 609 }
 610
 611 /**
 612  * Main function that will be run by the scheduler.
 613  *
 614  * @param cls closure
 615  * @param args remaining command-line arguments
 616  * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 617  * @param cfg configuration
 618  */
 619 static void
 620 run (void *cls,
 621      char *const *args,
 622      const char *cfgfile,
 623      const struct GNUNET_CONFIGURATION_Handle *cfg_) {
 624     mst = GNUNET_SERVER_mst_create(&message_token, NULL);
 625     cfg = cfg_;
 626     restart_hijack = 0;
 627     GNUNET_SCHEDULER_add_now (connect_to_service_dns, NULL);
 628     GNUNET_SCHEDULER_add_now (start_helper_and_schedule, NULL);
 629     GNUNET_SCHEDULER_add_delayed(GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls);
 630 }
 631
 632 /**
 633  * The main function to obtain template from gnunetd.
 634  *
 635  * @param argc number of arguments from the command line
 636  * @param argv command line arguments
 637  * @return 0 ok, 1 on error
 638  */
 639 int
 640 main (int argc, char *const *argv) {
 641     static const struct GNUNET_GETOPT_CommandLineOption options[] = {
 642         GNUNET_GETOPT_OPTION_END
 643     };
 644
 645     return (GNUNET_OK ==
 646             GNUNET_PROGRAM_run (argc,
 647                                 argv,
 648                                 "gnunet-daemon-vpn",
 649                                 gettext_noop ("help text"),
 650                                 options, &run, NULL)) ? ret : 1;
 651 }
 652
 653 /* end of gnunet-daemon-vpn.c */