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