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 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 || 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     GNUNET_OS_process_kill (helper_proc, SIGTERM);
 181     GNUNET_OS_process_wait (helper_proc);
 182     GNUNET_OS_process_close (helper_proc);
 183     helper_proc = NULL;
 184
 185     /* close the connection to the service-dns */
 186     if (dns_connection != NULL)
 187       {
 188         GNUNET_CLIENT_disconnect (dns_connection, GNUNET_NO);
 189         dns_connection = NULL;
 190       }
 191 }
 192
 193 /**
 194  * Start the helper-process
 195  */
 196 static void
 197 start_helper_and_schedule(void *cls,
 198                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
 199     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 200       return;
 201
 202     helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO);
 203     helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_NO, GNUNET_YES);
 204
 205     if (helper_in == NULL || helper_out == NULL) return;
 206
 207     helper_proc = GNUNET_OS_start_process(helper_in, helper_out, "gnunet-helper-vpn", "gnunet-helper-vpn", NULL);
 208
 209     fh_from_helper = GNUNET_DISK_pipe_handle (helper_out, GNUNET_DISK_PIPE_END_READ);
 210     fh_to_helper = GNUNET_DISK_pipe_handle (helper_in, GNUNET_DISK_PIPE_END_WRITE);
 211
 212     GNUNET_DISK_pipe_close_end(helper_out, GNUNET_DISK_PIPE_END_WRITE);
 213     GNUNET_DISK_pipe_close_end(helper_in, GNUNET_DISK_PIPE_END_READ);
 214
 215     GNUNET_SCHEDULER_add_read_file (sched, GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 216 }
 217
 218 /**
 219  * Restart the helper-process
 220  */
 221 static void
 222 restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 223     // Kill the helper
 224     GNUNET_OS_process_kill (helper_proc, SIGKILL);
 225     GNUNET_OS_process_wait (helper_proc);
 226     GNUNET_OS_process_close (helper_proc);
 227     helper_proc = NULL;
 228
 229     /* Tell the dns-service to rehijack the dns-port
 230      * The routing-table gets flushed if an interface disappears.
 231      */
 232     restart_hijack = 1;
 233     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 234
 235     GNUNET_DISK_pipe_close(helper_in);
 236     GNUNET_DISK_pipe_close(helper_out);
 237
 238     /* Restart the helper */
 239     GNUNET_SCHEDULER_add_delayed (sched, GNUNET_TIME_UNIT_SECONDS, start_helper_and_schedule, NULL);
 240 }
 241
 242 /**
 243  * Read from the helper-process
 244  */
 245 static void
 246 helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 247     /* no message can be bigger then 64k */
 248     char buf[65535];
 249
 250     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 251       return;
 252
 253     int t = GNUNET_DISK_file_read(fh_from_helper, &buf, 65535);
 254
 255     /* On read-error, restart the helper */
 256     if (t<=0) {
 257         GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Read error for header from vpn-helper: %m\n");
 258         GNUNET_SCHEDULER_add_now(sched, restart_helper, cls);
 259         return;
 260     }
 261
 262     /* FIXME */ GNUNET_SERVER_mst_receive(mst, NULL, buf, t, 0, 0);
 263
 264     GNUNET_SCHEDULER_add_read_file (sched, GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 265 }
 266
 267 /**
 268  * Calculate the checksum of an IPv4-Header
 269  */
 270 static uint16_t
 271 calculate_ip_checksum(uint16_t* hdr, short len) {
 272     uint32_t sum = 0;
 273     for(; len >= 2; len -= 2)
 274       sum += *(hdr++);
 275     if (len == 1)
 276       sum += *((unsigned char*)hdr);
 277
 278     sum = (sum >> 16) + (sum & 0xFFFF);
 279
 280     return ~sum;
 281 }
 282
 283 /**
 284  * Send an dns-answer-packet to the helper
 285  */
 286 static void
 287 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 288     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 289       return;
 290
 291     struct answer_packet_list* ans = answer_proc_head;
 292     size_t len = ntohs(ans->pkt.hdr.size);
 293
 294     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 295
 296     size_t data_len = len - sizeof(struct answer_packet) + 1;
 297     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 298     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 299
 300     struct ip_udp_dns* pkt = alloca(pkt_len);
 301     memset(pkt, 0, pkt_len);
 302
 303     /* set the gnunet-header */
 304     pkt->shdr.size = htons(pkt_len);
 305     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 306
 307     /* set the tun-header (no flags and ethertype of IPv4) */
 308     pkt->tun.flags = 0;
 309     pkt->tun.type = htons(0x0800);
 310
 311     /* set the ip-header */
 312     pkt->ip_hdr.version = 4;
 313     pkt->ip_hdr.hdr_lngth = 5;
 314     pkt->ip_hdr.diff_serv = 0;
 315     pkt->ip_hdr.tot_lngth = htons(net_len);
 316     pkt->ip_hdr.ident = 0;
 317     pkt->ip_hdr.flags = 0;
 318     pkt->ip_hdr.frag_off = 0;
 319     pkt->ip_hdr.ttl = 255;
 320     pkt->ip_hdr.proto = 0x11; /* UDP */
 321     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 322     pkt->ip_hdr.sadr = ans->pkt.from;
 323     pkt->ip_hdr.dadr = ans->pkt.to;
 324
 325     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 326
 327     /* set the udp-header */
 328     pkt->udp_dns.udp_hdr.spt = htons(53);
 329     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 330     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 331     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 332
 333     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 334
 335     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 336     GNUNET_free(ans);
 337
 338     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, pkt, pkt_len);
 339
 340     /* if more packets are available, reschedule */
 341     if (answer_proc_head != NULL)
 342       GNUNET_SCHEDULER_add_write_file (sched,
 343                                        GNUNET_TIME_UNIT_FOREVER_REL,
 344                                        fh_to_helper,
 345                                        &helper_write,
 346                                        NULL);
 347 }
 348
 349 /**
 350  * Receive packets from the helper-process
 351  */
 352 static void
 353 message_token(void *cls,
 354               void *client,
 355               const struct GNUNET_MessageHeader *message) {
 356     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 357
 358     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 359
 360     /* ethertype is ipv6 */
 361     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 362       {
 363         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 364         struct ip6_tcp *pkt6_tcp;
 365         struct ip6_udp *pkt6_udp;
 366
 367         pkt_printf(pkt6);
 368         switch(pkt6->ip6_hdr.nxthdr)
 369           {
 370           case 0x06:
 371             pkt6_tcp = (struct ip6_tcp*)pkt6;
 372             pkt_printf_ip6tcp(pkt6_tcp);
 373             break;
 374           case 0x11:
 375             pkt6_udp = (struct ip6_udp*)pkt6;
 376             pkt_printf_ip6udp(pkt6_udp);
 377             if (ntohs(pkt6_udp->udp_hdr.dpt) == 53) {
 378                 pkt_printf_ip6dns((struct ip6_udp_dns*)pkt6_udp);
 379             }
 380             break;
 381           }
 382       }
 383     /* ethertype is ipv4 */
 384     else if (ntohs(pkt_tun->tun.type) == 0x0800)
 385       {
 386         struct ip_pkt *pkt = (struct ip_pkt*) message;
 387         struct ip_udp *udp = (struct ip_udp*) message;
 388         GNUNET_assert(pkt->ip_hdr.version == 4);
 389
 390         /* Send dns-packets to the service-dns */
 391         if (pkt->ip_hdr.proto == 0x11 && ntohs(udp->udp_hdr.dpt) == 53 )
 392           {
 393             /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 394             size_t len = sizeof(struct query_packet) + ntohs(udp->udp_hdr.len) - 9;
 395
 396             struct query_packet_list* query = GNUNET_malloc(len + 2*sizeof(struct query_packet_list*));
 397             query->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 398             query->pkt.hdr.size = htons(len);
 399             query->pkt.orig_to = pkt->ip_hdr.dadr;
 400             query->pkt.orig_from = pkt->ip_hdr.sadr;
 401             query->pkt.src_port = udp->udp_hdr.spt;
 402             memcpy(query->pkt.data, udp->data, ntohs(udp->udp_hdr.len) - 8);
 403
 404             GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, query);
 405
 406             if (dns_connection != NULL)
 407               GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 408                                                   len,
 409                                                   GNUNET_TIME_UNIT_FOREVER_REL,
 410                                                   GNUNET_YES,
 411                                                   &send_query,
 412                                                   NULL);
 413           }
 414       }
 415 }
 416
 417 /**
 418  * Connect to the service-dns
 419  */
 420 static void
 421 connect_to_service_dns (void *cls,
 422                         const struct GNUNET_SCHEDULER_TaskContext *tc) {
 423     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
 424       return;
 425     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Connecting to service-dns\n");
 426     GNUNET_assert (dns_connection == NULL);
 427     dns_connection = GNUNET_CLIENT_connect (sched, "dns", cfg);
 428     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 429
 430     /* If a packet is already in the list, schedule to send it */
 431     if (head != NULL)
 432       GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 433                                           ntohs(head->pkt.hdr.size),
 434                                           GNUNET_TIME_UNIT_FOREVER_REL,
 435                                           GNUNET_YES,
 436                                           &send_query,
 437                                           NULL);
 438 }
 439
 440 /**
 441  * This gets scheduled with cls pointing to an answer_packet and does everything
 442  * needed in order to send it to the helper.
 443  *
 444  * At the moment this means "inventing" and IPv6-Address for .gnunet-services and
 445  * doing nothing for "real" services.
 446  */
 447 static void
 448 process_answer(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tc) {
 449     struct answer_packet* pkt = cls;
 450
 451     /* This answer is about a .gnunet-service
 452      *
 453      * It contains an almost complete DNS-Response, we have to fill in the ip
 454      * at the offset pkt->addroffset
 455      */
 456     if (pkt->subtype == GNUNET_DNS_ANSWER_TYPE_SERVICE)
 457       {
 458         unsigned char ip6addr[16];
 459
 460         pkt->subtype = GNUNET_DNS_ANSWER_TYPE_IP;
 461         memcpy(ip6addr, (int[]){htons(0x1234)}, 2);
 462         memcpy(ip6addr+2, &pkt->peer, 7);
 463         memcpy(ip6addr+9, &pkt->service_descriptor, 7);
 464
 465         memcpy(((char*)pkt)+ntohs(pkt->addroffset), ip6addr, 16);
 466
 467           /*FIXME:
 468            * -save DNS_Record into hashmap, pointed to by ip
 469            * -regularily walk through hashmap, deleting old entries
 470            *  when is an entry old?
 471            *  have a last-used field
 472            *  don't remove if last-used "recent", ask dht again if record expired
 473            */
 474       }
 475
 476     struct answer_packet_list* list = GNUNET_malloc(htons(pkt->hdr.size) + 2*sizeof(struct answer_packet_list*));
 477
 478     memcpy(&list->pkt, pkt, htons(pkt->hdr.size));
 479
 480     GNUNET_CONTAINER_DLL_insert_after(answer_proc_head, answer_proc_tail, answer_proc_tail, list);
 481
 482     GNUNET_SCHEDULER_add_write_file (sched, GNUNET_TIME_UNIT_FOREVER_REL, fh_to_helper, &helper_write, NULL);
 483
 484     return;
 485 }
 486
 487 /**
 488  * This receives packets from the service-dns and schedules process_answer to
 489  * handle it
 490  */
 491 static void
 492 dns_answer_handler(void* cls, const struct GNUNET_MessageHeader *msg) {
 493     /* the service disconnected, reconnect after short wait */
 494     if (msg == NULL)
 495       {
 496         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 497         dns_connection = NULL;
 498         GNUNET_SCHEDULER_add_delayed (sched,
 499                                       GNUNET_TIME_UNIT_SECONDS,
 500                                       &connect_to_service_dns,
 501                                       NULL);
 502         return;
 503       }
 504
 505     /* the service did something strange, reconnect immediately */
 506     if (msg->type != htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS))
 507       {
 508         GNUNET_break (0);
 509         GNUNET_CLIENT_disconnect(dns_connection, GNUNET_NO);
 510         dns_connection = NULL;
 511         GNUNET_SCHEDULER_add_now (sched,
 512                                   &connect_to_service_dns,
 513                                   NULL);
 514         return;
 515       }
 516     void *pkt = GNUNET_malloc(ntohs(msg->size));
 517
 518     memcpy(pkt, msg, ntohs(msg->size));
 519
 520     GNUNET_SCHEDULER_add_now(sched, process_answer, pkt);
 521     GNUNET_CLIENT_receive(dns_connection, &dns_answer_handler, NULL, GNUNET_TIME_UNIT_FOREVER_REL);
 522 }
 523
 524 /**
 525  * Main function that will be run by the scheduler.
 526  *
 527  * @param cls closure
 528  * @param sched the scheduler to use
 529  * @param args remaining command-line arguments
 530  * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 531  * @param cfg configuration
 532  */
 533 static void
 534 run (void *cls,
 535      struct GNUNET_SCHEDULER_Handle *sched_,
 536      char *const *args,
 537      const char *cfgfile,
 538      const struct GNUNET_CONFIGURATION_Handle *cfg_) {
 539     sched = sched_;
 540     mst = GNUNET_SERVER_mst_create(&message_token, NULL);
 541     cfg = cfg_;
 542     restart_hijack = 0;
 543     GNUNET_SCHEDULER_add_now (sched, connect_to_service_dns, NULL);
 544     GNUNET_SCHEDULER_add_now (sched, start_helper_and_schedule, NULL);
 545     GNUNET_SCHEDULER_add_delayed(sched, GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls);
 546 }
 547
 548 /**
 549  * The main function to obtain template from gnunetd.
 550  *
 551  * @param argc number of arguments from the command line
 552  * @param argv command line arguments
 553  * @return 0 ok, 1 on error
 554  */
 555 int
 556 main (int argc, char *const *argv) {
 557     static const struct GNUNET_GETOPT_CommandLineOption options[] = {
 558         GNUNET_GETOPT_OPTION_END
 559     };
 560
 561     return (GNUNET_OK ==
 562             GNUNET_PROGRAM_run (argc,
 563                                 argv,
 564                                 "gnunet-daemon-vpn",
 565                                 gettext_noop ("help text"),
 566                                 options, &run, NULL)) ? ret : 1;
 567 }
 568
 569 /* end of gnunet-daemon-vpn.c */