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 Tölke
  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 scheduler to use throughout the daemon
  48  */
  49 static struct GNUNET_SCHEDULER_Handle *sched;
  50
  51 /**
  52  * The configuration to use
  53  */
  54 static const struct GNUNET_CONFIGURATION_Handle *cfg;
  55
  56 /**
  57  * PipeHandle to receive data from the helper
  58  */
  59 static struct GNUNET_DISK_PipeHandle* helper_in;
  60
  61 /**
  62  * PipeHandle to send data to the helper
  63  */
  64 static struct GNUNET_DISK_PipeHandle* helper_out;
  65
  66 /**
  67  * FileHandle to receive data from the helper
  68  */
  69 static const struct GNUNET_DISK_FileHandle* fh_from_helper;
  70
  71 /**
  72  * FileHandle to send data to the helper
  73  */
  74 static const struct GNUNET_DISK_FileHandle* fh_to_helper;
  75
  76 /**
  77  * The Message-Tokenizer that tokenizes the messages comming from the helper
  78  */
  79 static struct GNUNET_SERVER_MessageStreamTokenizer* mst;
  80
  81 /**
  82  * The connection to the service-dns
  83  */
  84 static struct GNUNET_CLIENT_Connection *dns_connection;
  85
  86 /**
  87  * A flag to show that the service-dns has to rehijack the outbound dns-packets
  88  *
  89  * This gets set when the helper restarts as the routing-tables are flushed when
  90  * the interface vanishes.
  91  */
  92 static unsigned char restart_hijack;
  93
  94 /**
  95  * The process id of the helper
  96  */
  97 static struct GNUNET_OS_Process *helper_proc;
  98
  99 /**
 100  * a list of outgoing dns-query-packets
 101  */
 102 static struct query_packet_list *head;
 103
 104 /**
 105  * The last element of the list of outgoing dns-query-packets
 106  */
 107 static struct query_packet_list *tail;
 108
 109 /**
 110  * A list of processed dns-responses.
 111  *
 112  * "processed" means that the packet is complete and can be sent out via udp
 113  * directly
 114  */
 115 static struct answer_packet_list *answer_proc_head;
 116
 117 /**
 118  * The last element of the list of processed dns-responses.
 119  */
 120 static struct answer_packet_list *answer_proc_tail;
 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     GNUNET_OS_process_kill (helper_proc, SIGTERM);
 185     GNUNET_OS_process_wait (helper_proc);
 186     GNUNET_OS_process_close (helper_proc);
 187     helper_proc = NULL;
 188
 189     /* close the connection to the service-dns */
 190     if (dns_connection != NULL)
 191       {
 192         GNUNET_CLIENT_disconnect (dns_connection, GNUNET_NO);
 193         dns_connection = NULL;
 194       }
 195 }
 196
 197 /**
 198  * Start the helper-process
 199  */
 200 static void
 201 start_helper_and_schedule(void *cls,
 202                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
 203     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 204       return;
 205
 206     helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO);
 207     helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_NO, GNUNET_YES);
 208
 209     if (helper_in == NULL || helper_out == NULL) return;
 210
 211     helper_proc = GNUNET_OS_start_process(helper_in, helper_out, "gnunet-helper-vpn", "gnunet-helper-vpn", NULL);
 212
 213     fh_from_helper = GNUNET_DISK_pipe_handle (helper_out, GNUNET_DISK_PIPE_END_READ);
 214     fh_to_helper = GNUNET_DISK_pipe_handle (helper_in, GNUNET_DISK_PIPE_END_WRITE);
 215
 216     GNUNET_DISK_pipe_close_end(helper_out, GNUNET_DISK_PIPE_END_WRITE);
 217     GNUNET_DISK_pipe_close_end(helper_in, GNUNET_DISK_PIPE_END_READ);
 218
 219     /* Tell the dns-service to rehijack the dns-port
 220      * The routing-table gets flushed if an interface disappears.
 221      */
 222     restart_hijack = 1;
 223     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 224
 225     GNUNET_SCHEDULER_add_read_file (sched, GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 226 }
 227
 228 /**
 229  * Restart the helper-process
 230  */
 231 static void
 232 restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 233     // Kill the helper
 234     GNUNET_OS_process_kill (helper_proc, SIGKILL);
 235     GNUNET_OS_process_wait (helper_proc);
 236     GNUNET_OS_process_close (helper_proc);
 237     helper_proc = NULL;
 238
 239     GNUNET_DISK_pipe_close(helper_in);
 240     GNUNET_DISK_pipe_close(helper_out);
 241
 242     /* Restart the helper */
 243     GNUNET_SCHEDULER_add_delayed (sched, GNUNET_TIME_UNIT_SECONDS, start_helper_and_schedule, NULL);
 244 }
 245
 246 /**
 247  * Read from the helper-process
 248  */
 249 static void
 250 helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 251     /* no message can be bigger then 64k */
 252     char buf[65535];
 253
 254     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 255       return;
 256
 257     int t = GNUNET_DISK_file_read(fh_from_helper, &buf, 65535);
 258
 259     /* On read-error, restart the helper */
 260     if (t<=0) {
 261         GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Read error for header from vpn-helper: %m\n");
 262         GNUNET_SCHEDULER_add_now(sched, restart_helper, cls);
 263         return;
 264     }
 265
 266     /* FIXME */ GNUNET_SERVER_mst_receive(mst, NULL, buf, t, 0, 0);
 267
 268     GNUNET_SCHEDULER_add_read_file (sched, GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 269 }
 270
 271 /**
 272  * Calculate the checksum of an IPv4-Header
 273  */
 274 static uint16_t
 275 calculate_ip_checksum(uint16_t* hdr, short len) {
 276     uint32_t sum = 0;
 277     for(; len >= 2; len -= 2)
 278       sum += *(hdr++);
 279     if (len == 1)
 280       sum += *((unsigned char*)hdr);
 281
 282     sum = (sum >> 16) + (sum & 0xFFFF);
 283
 284     return ~sum;
 285 }
 286
 287 /**
 288  * Send an dns-answer-packet to the helper
 289  */
 290 static void
 291 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 292     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 293       return;
 294
 295     struct answer_packet_list* ans = answer_proc_head;
 296     size_t len = ntohs(ans->pkt.hdr.size);
 297
 298     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 299
 300     size_t data_len = len - sizeof(struct answer_packet) + 1;
 301     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 302     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 303
 304     struct ip_udp_dns* pkt = alloca(pkt_len);
 305     memset(pkt, 0, pkt_len);
 306
 307     /* set the gnunet-header */
 308     pkt->shdr.size = htons(pkt_len);
 309     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 310
 311     /* set the tun-header (no flags and ethertype of IPv4) */
 312     pkt->tun.flags = 0;
 313     pkt->tun.type = htons(0x0800);
 314
 315     /* set the ip-header */
 316     pkt->ip_hdr.version = 4;
 317     pkt->ip_hdr.hdr_lngth = 5;
 318     pkt->ip_hdr.diff_serv = 0;
 319     pkt->ip_hdr.tot_lngth = htons(net_len);
 320     pkt->ip_hdr.ident = 0;
 321     pkt->ip_hdr.flags = 0;
 322     pkt->ip_hdr.frag_off = 0;
 323     pkt->ip_hdr.ttl = 255;
 324     pkt->ip_hdr.proto = 0x11; /* UDP */
 325     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 326     pkt->ip_hdr.sadr = ans->pkt.from;
 327     pkt->ip_hdr.dadr = ans->pkt.to;
 328
 329     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 330
 331     /* set the udp-header */
 332     pkt->udp_dns.udp_hdr.spt = htons(53);
 333     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 334     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 335     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 336
 337     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 338
 339     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 340     GNUNET_free(ans);
 341
 342     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, pkt, pkt_len);
 343
 344     /* if more packets are available, reschedule */
 345     if (answer_proc_head != NULL)
 346       GNUNET_SCHEDULER_add_write_file (sched,
 347                                        GNUNET_TIME_UNIT_FOREVER_REL,
 348                                        fh_to_helper,
 349                                        &helper_write,
 350                                        NULL);
 351 }
 352
 353 static int
 354 address_mapping_exists(unsigned char addr[]) {
 355     return 1;
 356 }
 357
 358 static void
 359 send_icmp_response(void* cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
 360     struct ip6_icmp* request = cls;
 361
 362     struct ip6_icmp* response = alloca(ntohs(request->shdr.size));
 363     memset(response, 0, ntohs(request->shdr.size));
 364
 365     response->shdr.size = request->shdr.size;
 366     response->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 367
 368     response->tun.flags = 0;
 369     response->tun.type = htons(0x86dd);
 370
 371     response->ip6_hdr.hoplmt = 255;
 372     response->ip6_hdr.paylgth = request->ip6_hdr.paylgth;
 373     response->ip6_hdr.nxthdr = 0x3a;
 374     response->ip6_hdr.version = 6;
 375     memcpy(&response->ip6_hdr.sadr, &request->ip6_hdr.dadr, 16);
 376     memcpy(&response->ip6_hdr.dadr, &request->ip6_hdr.sadr, 16);
 377
 378     response->icmp_hdr.code = 0;
 379     response->icmp_hdr.type = 0x81;
 380
 381     /* Magic, more Magic! */
 382     response->icmp_hdr.chks = request->icmp_hdr.chks - 0x1;
 383
 384     /* Copy the rest of the packet */
 385     memcpy(response+1, request+1, ntohs(request->shdr.size) - sizeof(struct ip6_icmp));
 386
 387     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, response, ntohs(response->shdr.size));
 388
 389     GNUNET_free(request);
 390 }
 391
 392 /**
 393  * Receive packets from the helper-process
 394  */
 395 static void
 396 message_token(void *cls,
 397               void *client,
 398               const struct GNUNET_MessageHeader *message) {
 399     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 400
 401     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 402
 403     /* ethertype is ipv6 */
 404     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 405       {
 406         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 407         GNUNET_assert(pkt6->ip6_hdr.version == 6);
 408         struct ip6_tcp *pkt6_tcp;
 409         struct ip6_udp *pkt6_udp;
 410         struct ip6_icmp *pkt6_icmp;
 411
 412         pkt_printf(pkt6);
 413         switch(pkt6->ip6_hdr.nxthdr)
 414           {
 415           case 0x06:
 416             pkt6_tcp = (struct ip6_tcp*)pkt6;
 417             pkt_printf_ip6tcp(pkt6_tcp);
 418             break;
 419           case 0x11:
 420             pkt6_udp = (struct ip6_udp*)pkt6;
 421             pkt_printf_ip6udp(pkt6_udp);
 422             if (ntohs(pkt6_udp->udp_hdr.dpt) == 53) {
 423                 pkt_printf_ip6dns((struct ip6_udp_dns*)pkt6_udp);
 424             }
 425             break;
 426           case 0x3a:
 427             /* ICMPv6 */
 428             pkt6_icmp = GNUNET_malloc(ntohs(pkt6->shdr.size));
 429             memcpy(pkt6_icmp, pkt6, ntohs(pkt6->shdr.size));
 430             /* If this packet is an icmp-echo-request and a mapping exists, answer */
 431             if (pkt6_icmp->icmp_hdr.type == 0x80 && address_mapping_exists(pkt6->ip6_hdr.sadr))
 432                 GNUNET_SCHEDULER_add_now(sched, &send_icmp_response, pkt6_icmp);
 433             break;
 434           }
 435       }
 436     /* ethertype is ipv4 */
 437     else if (ntohs(pkt_tun->tun.type) == 0x0800)
 438       {
 439         struct ip_pkt *pkt = (struct ip_pkt*) message;
 440         struct ip_udp *udp = (struct ip_udp*) message;
 441         GNUNET_assert(pkt->ip_hdr.version == 4);
 442
 443         /* Send dns-packets to the service-dns */
 444         if (pkt->ip_hdr.proto == 0x11 && ntohs(udp->udp_hdr.dpt) == 53 )
 445           {
 446             /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 447             size_t len = sizeof(struct query_packet) + ntohs(udp->udp_hdr.len) - 9;
 448
 449             struct query_packet_list* query = GNUNET_malloc(len + 2*sizeof(struct query_packet_list*));
 450             query->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 451             query->pkt.hdr.size = htons(len);
 452             query->pkt.orig_to = pkt->ip_hdr.dadr;
 453             query->pkt.orig_from = pkt->ip_hdr.sadr;
 454             query->pkt.src_port = udp->udp_hdr.spt;
 455             memcpy(query->pkt.data, udp->data, ntohs(udp->udp_hdr.len) - 8);
 456
 457             GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, query);
 458
 459             if (dns_connection != NULL)
 460               GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 461                                                   len,
 462                                                   GNUNET_TIME_UNIT_FOREVER_REL,
 463                                                   GNUNET_YES,
 464                                                   &send_query,
 465                                                   NULL);
 466           }
 467       }
 468 }
 469
 470 /**
 471  * Connect to the service-dns
 472  */
 473 static void
 474 connect_to_service_dns (void *cls,
 475                         const struct GNUNET_SCHEDULER_TaskContext *tc) {
 476     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 477       return;
 478     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Connecting to service-dns\n");
 479     GNUNET_assert (dns_connection == NULL);
 480     dns_connection = GNUNET_CLIENT_connect (sched, "dns", cfg);
 481     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 482
 483     /* If a packet is already in the list, schedule to send it */
 484     if (head != NULL)
 485       GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 486                                           ntohs(head->pkt.hdr.size),
 487                                           GNUNET_TIME_UNIT_FOREVER_REL,
 488                                           GNUNET_YES,
 489                                           &send_query,
 490                                           NULL);
 491     else if (restart_hijack == 1)
 492       {
 493         GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 494       }
 495 }
 496
 497 /**
 498  * This gets scheduled with cls pointing to an answer_packet and does everything
 499  * needed in order to send it to the helper.
 500  *
 501  * At the moment this means "inventing" and IPv6-Address for .gnunet-services and
 502  * doing nothing for "real" services.
 503  */
 504 static void
 505 process_answer(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tc) {
 506     struct answer_packet* pkt = cls;
 507     struct answer_packet_list* list;
 508
 509     /* This answer is about a .gnunet-service
 510      *
 511      * It contains an almost complete DNS-Response, we have to fill in the ip
 512      * at the offset pkt->addroffset
 513      */
 514     //FIXME htons?
 515     if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_SERVICE)
 516       {
 517         unsigned char ip6addr[16];
 518
 519         pkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 520         memcpy(ip6addr, (int[]){htons(0x1234)}, 2);
 521         memcpy(ip6addr+2, &pkt->peer, 7);
 522         memcpy(ip6addr+9, &pkt->service_descriptor, 7);
 523
 524         memcpy(((char*)pkt)+ntohs(pkt->addroffset), ip6addr, 16);
 525
 526           /*FIXME:
 527            * -save DNS_Record into hashmap, pointed to by ip
 528            * -regularily walk through hashmap, deleting old entries
 529            *  when is an entry old?
 530            *  have a last-used field
 531            *  don't remove if last-used "recent", ask dht again if record expired
 532            */
 533
 534         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 535
 536         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 537       }
 538     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_REV)
 539       {
 540         unsigned short offset = ntohs(pkt->addroffset);
 541
 542         unsigned short namelen = htons(22); /* calculate the length of the answer */
 543         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};
 544
 545         list = GNUNET_malloc(2*sizeof(struct answer_packet_list*) + offset + 2 + ntohs(namelen));
 546
 547         struct answer_packet* rpkt = &list->pkt;
 548
 549         memcpy(rpkt, pkt, offset);
 550
 551         rpkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 552         rpkt->hdr.size = ntohs(offset + 2 + ntohs(namelen));
 553
 554         memcpy(((char*)rpkt)+offset, &namelen, 2);
 555         memcpy(((char*)rpkt)+offset+2, name, ntohs(namelen));
 556
 557       }
 558     else if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_IP)
 559       {
 560         list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 561         memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 562       }
 563
 564     GNUNET_free(pkt);
 565
 566     GNUNET_CONTAINER_DLL_insert_after(answer_proc_head, answer_proc_tail, answer_proc_tail, list);
 567
 568     GNUNET_SCHEDULER_add_write_file (sched, GNUNET_TIME_UNIT_FOREVER_REL, fh_to_helper, &helper_write, NULL);
 569
 570     return;
 571 }
 572
 573 /**
 574  * This receives packets from the service-dns and schedules process_answer to
 575  * handle it
 576  */
 577 static void
 578 dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg) {
 579     /* the service disconnected, reconnect after short wait */
 580     if (msg == NULL)
 581       {
 582         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 583         dns_connection = NULL;
 584         GNUNET_SCHEDULER_add_delayed (sched,
 585                                       GNUNET_TIME_UNIT_SECONDS,
 586                                       &connect_to_service_dns,
 587                                       NULL);
 588         return;
 589       }
 590
 591     /* the service did something strange, reconnect immediately */
 592     if (msg->type != htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS))
 593       {
 594         GNUNET_break (0);
 595         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 596         dns_connection = NULL;
 597         GNUNET_SCHEDULER_add_now (sched,
 598                                   &connect_to_service_dns,
 599                                   NULL);
 600         return;
 601       }
 602     void *pkt = GNUNET_malloc(ntohs(msg->size));
 603
 604     memcpy(pkt, msg, ntohs(msg->size));
 605
 606     GNUNET_SCHEDULER_add_now(sched, process_answer, pkt);
 607     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 608 }
 609
 610 /**
 611  * Main function that will be run by the scheduler.
 612  *
 613  * @param cls closure
 614  * @param sched the scheduler to use
 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      struct GNUNET_SCHEDULER_Handle *sched_,
 622      char *const *args,
 623      const char *cfgfile,
 624      const struct GNUNET_CONFIGURATION_Handle *cfg_) {
 625     sched = sched_;
 626     mst = GNUNET_SERVER_mst_create(&message_token, NULL);
 627     cfg = cfg_;
 628     restart_hijack = 0;
 629     GNUNET_SCHEDULER_add_now (sched, connect_to_service_dns, NULL);
 630     GNUNET_SCHEDULER_add_now (sched, start_helper_and_schedule, NULL);
 631     GNUNET_SCHEDULER_add_delayed(sched, GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls);
 632 }
 633
 634 /**
 635  * The main function to obtain template from gnunetd.
 636  *
 637  * @param argc number of arguments from the command line
 638  * @param argv command line arguments
 639  * @return 0 ok, 1 on error
 640  */
 641 int
 642 main (int argc, char *const *argv) {
 643     static const struct GNUNET_GETOPT_CommandLineOption options[] = {
 644         GNUNET_GETOPT_OPTION_END
 645     };
 646
 647     return (GNUNET_OK ==
 648             GNUNET_PROGRAM_run (argc,
 649                                 argv,
 650                                 "gnunet-daemon-vpn",
 651                                 gettext_noop ("help text"),
 652                                 options, &run, NULL)) ? ret : 1;
 653 }
 654
 655 /* end of gnunet-daemon-vpn.c */