src/vpn/gnunet-daemon-vpn-helper.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-helper.c
  23  * @brief
  24  * @author Philipp Toelke
  25  */
  26 #include <platform.h>
  27 #include <gnunet_common.h>
  28 #include <gnunet_client_lib.h>
  29 #include <gnunet_os_lib.h>
  30 #include <gnunet_mesh_service.h>
  31 #include <gnunet_protocols.h>
  32 #include <gnunet_server_lib.h>
  33 #include <gnunet_container_lib.h>
  34 #include <block_dns.h>
  35 #include <gnunet_configuration_lib.h>
  36 #include <gnunet_applications.h>
  37
  38 #include "gnunet-daemon-vpn-dns.h"
  39 #include "gnunet-daemon-vpn.h"
  40 #include "gnunet-daemon-vpn-helper.h"
  41 #include "gnunet-service-dns-p.h"
  42 #include "gnunet-vpn-packet.h"
  43 #include "gnunet-vpn-checksum.h"
  44 #include "gnunet-helper-vpn-api.h"
  45
  46 struct GNUNET_VPN_HELPER_Handle *helper_handle;
  47
  48 /**
  49  * The tunnels that will be used to send tcp- and udp-packets
  50  */
  51 static struct GNUNET_MESH_Tunnel* tcp_tunnel;
  52 static struct GNUNET_MESH_Tunnel* udp_tunnel;
  53
  54 /**
  55  * Start the helper-process
  56  *
  57  * If cls != NULL it is assumed that this function is called as a result of a dying
  58  * helper. cls is then taken as handle to the old helper and is cleaned up.
  59  * {{{
  60  */
  61 void
  62 start_helper_and_schedule(void *cls,
  63                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
  64   shs_task = GNUNET_SCHEDULER_NO_TASK;
  65     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
  66       return;
  67
  68     if (cls != NULL)
  69       cleanup_helper(cls);
  70     cls = NULL;
  71
  72     char* ifname;
  73     char* ipv6addr;
  74     char* ipv6prefix;
  75     char* ipv4addr;
  76     char* ipv4mask;
  77
  78     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IFNAME", &ifname))
  79       {
  80         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IFNAME' in configuration!\n");
  81         exit(1);
  82       }
  83
  84     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6ADDR", &ipv6addr))
  85       {
  86         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6ADDR' in configuration!\n");
  87         exit(1);
  88       }
  89
  90     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6PREFIX", &ipv6prefix))
  91       {
  92         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6PREFIX' in configuration!\n");
  93         exit(1);
  94       }
  95
  96     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4ADDR", &ipv4addr))
  97       {
  98         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4ADDR' in configuration!\n");
  99         exit(1);
 100       }
 101
 102     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4MASK", &ipv4mask))
 103       {
 104         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4MASK' in configuration!\n");
 105         exit(1);
 106       }
 107
 108     /* Start the helper
 109      * Messages get passed to the function message_token
 110      * When the helper dies, this function will be called again with the
 111      * helper_handle as cls.
 112      */
 113     helper_handle = start_helper(ifname,
 114                                  ipv6addr,
 115                                  ipv6prefix,
 116                                  ipv4addr,
 117                                  ipv4mask,
 118                                  "vpn-gnunet",
 119                                  start_helper_and_schedule,
 120                                  message_token,
 121                                  NULL);
 122
 123     GNUNET_free(ipv6addr);
 124     GNUNET_free(ipv6prefix);
 125     GNUNET_free(ipv4addr);
 126     GNUNET_free(ipv4mask);
 127     GNUNET_free(ifname);
 128
 129     /* Tell the dns-service to rehijack the dns-port
 130      * The routing-table gets flushed if an interface disappears.
 131      */
 132     restart_hijack = 1;
 133     if (NULL != dns_connection)
 134       GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 135
 136     GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL, helper_handle->fh_to_helper, &helper_write, NULL);
 137 }
 138 /*}}}*/
 139
 140 /**
 141  * Send an dns-answer-packet to the helper
 142  */
 143 void
 144 helper_write(void* cls __attribute__((unused)), const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 145     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 146       return;
 147
 148     struct answer_packet_list* ans = answer_proc_head;
 149
 150     if (NULL == ans) return;
 151
 152     size_t len = ntohs(ans->pkt.hdr.size);
 153
 154     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 155
 156     GNUNET_assert (20 == sizeof (struct ip_hdr));
 157     GNUNET_assert (8 == sizeof (struct udp_pkt));
 158     size_t data_len = len - sizeof(struct answer_packet) + 1;
 159     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 160     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 161
 162     struct ip_udp_dns* pkt = alloca(pkt_len);
 163     GNUNET_assert(pkt != NULL);
 164     memset(pkt, 0, pkt_len);
 165
 166     /* set the gnunet-header */
 167     pkt->shdr.size = htons(pkt_len);
 168     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 169
 170     /* set the tun-header (no flags and ethertype of IPv4) */
 171     pkt->tun.flags = 0;
 172     pkt->tun.type = htons(0x0800);
 173
 174     /* set the ip-header */
 175     pkt->ip_hdr.version = 4;
 176     pkt->ip_hdr.hdr_lngth = 5;
 177     pkt->ip_hdr.diff_serv = 0;
 178     pkt->ip_hdr.tot_lngth = htons(net_len);
 179     pkt->ip_hdr.ident = 0;
 180     pkt->ip_hdr.flags = 0;
 181     pkt->ip_hdr.frag_off = 0;
 182     pkt->ip_hdr.ttl = 255;
 183     pkt->ip_hdr.proto = 0x11; /* UDP */
 184     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 185     pkt->ip_hdr.sadr = ans->pkt.from;
 186     pkt->ip_hdr.dadr = ans->pkt.to;
 187
 188     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 189
 190     /* set the udp-header */
 191     pkt->udp_dns.udp_hdr.spt = htons(53);
 192     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 193     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 194     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 195
 196     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 197
 198     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 199     GNUNET_free(ans);
 200
 201     if (GNUNET_DISK_file_write(helper_handle->fh_to_helper, pkt, pkt_len) < 0)
 202       {
 203         cleanup_helper(helper_handle);
 204         GNUNET_SCHEDULER_add_now(start_helper_and_schedule, NULL);
 205         return;
 206       }
 207
 208     /* if more packets are available, reschedule */
 209     if (answer_proc_head != NULL)
 210       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 211                                        helper_handle->fh_to_helper,
 212                                        &helper_write,
 213                                        NULL);
 214 }
 215
 216 /**
 217  * Receive packets from the helper-process
 218  */
 219 void
 220 message_token (void *cls __attribute__((unused)),
 221                void *client __attribute__((unused)), const struct GNUNET_MessageHeader *message)
 222 {
 223   GNUNET_assert (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 224
 225   struct tun_pkt *pkt_tun = (struct tun_pkt *) message;
 226
 227   /* ethertype is ipv6 */
 228   if (ntohs (pkt_tun->tun.type) == 0x86dd)
 229     {
 230       struct ip6_pkt *pkt6 = (struct ip6_pkt *) message;
 231       GNUNET_assert (pkt6->ip6_hdr.version == 6);
 232       struct ip6_tcp *pkt6_tcp;
 233       struct ip6_udp *pkt6_udp;
 234       struct ip6_icmp *pkt6_icmp;
 235       GNUNET_HashCode *key;
 236
 237       switch (pkt6->ip6_hdr.nxthdr)
 238         {
 239         case 0x06:             /* TCP */
 240         case 0x11:             /* UDP */
 241           pkt6_tcp = (struct ip6_tcp *) pkt6;
 242           pkt6_udp = (struct ip6_udp *) pkt6;
 243
 244           if ((key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 245             {
 246               struct map_entry *me =
 247                 GNUNET_CONTAINER_multihashmap_get (hashmap, key);
 248               GNUNET_assert (me != NULL);
 249               GNUNET_free (key);
 250
 251               size_t size =
 252                 sizeof (struct GNUNET_MESH_Tunnel *) +
 253                 sizeof (struct GNUNET_MessageHeader) +
 254                 sizeof (GNUNET_HashCode) + ntohs (pkt6->ip6_hdr.paylgth);
 255
 256               struct GNUNET_MESH_Tunnel **cls = GNUNET_malloc (size);
 257               struct GNUNET_MessageHeader *hdr =
 258                 (struct GNUNET_MessageHeader *) (cls + 1);
 259               GNUNET_HashCode *hc = (GNUNET_HashCode *) (hdr + 1);
 260
 261               hdr->size = htons (sizeof (struct GNUNET_MessageHeader) +
 262                                  sizeof (GNUNET_HashCode) +
 263                                  ntohs (pkt6->ip6_hdr.paylgth));
 264
 265               GNUNET_MESH_ApplicationType app_type;
 266               GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "me->addrlen is %d\n", me->addrlen);
 267               if (me->addrlen == 0)
 268                 {
 269                   /* This is a mapping to a gnunet-service */
 270                   memcpy (hc, &me->desc.service_descriptor,
 271                           sizeof (GNUNET_HashCode));
 272
 273                   if (0x11 == pkt6->ip6_hdr.nxthdr
 274                       && (me->desc.
 275                           service_type & htonl (GNUNET_DNS_SERVICE_TYPE_UDP))
 276                       && (port_in_ports (me->desc.ports, pkt6_udp->udp_hdr.dpt)
 277                           || testBit (me->additional_ports,
 278                                       ntohs (pkt6_udp->udp_hdr.dpt))))
 279                     {
 280                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_UDP);
 281
 282                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 283                               ntohs (pkt6_udp->udp_hdr.len));
 284
 285                     }
 286                   else if (0x06 == pkt6->ip6_hdr.nxthdr
 287                            && (me->desc.
 288                                service_type & htonl (GNUNET_DNS_SERVICE_TYPE_TCP))
 289                            &&
 290                            (port_in_ports (me->desc.ports, pkt6_tcp->tcp_hdr.dpt)))
 291                     {
 292                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_TCP);
 293
 294                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 295                               ntohs (pkt6->ip6_hdr.paylgth));
 296
 297                     }
 298                   if (me->tunnel == NULL && NULL != cls)
 299                     {
 300                       *cls =
 301                         GNUNET_MESH_peer_request_connect_all (mesh_handle,
 302                                                               GNUNET_TIME_UNIT_FOREVER_REL,
 303                                                               1,
 304                                                               (struct
 305                                                                GNUNET_PeerIdentity
 306                                                                *) &me->desc.peer,
 307                                                               send_pkt_to_peer,
 308                                                               NULL, cls);
 309                       me->tunnel = *cls;
 310                     }
 311                   else if (NULL != cls)
 312                     {
 313                       *cls = me->tunnel;
 314                       send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1,
 315                                         NULL);
 316                       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 317                                   "Queued to send to peer %x, type %d\n",
 318                                   *((unsigned int *) &me->desc.peer), ntohs(hdr->type));
 319                     }
 320                 }
 321               else
 322                 {
 323                   /* This is a mapping to a "real" address */
 324                   struct remote_addr *s = (struct remote_addr*) hc;
 325                   s->addrlen = me->addrlen;
 326                   memcpy(s->addr, me->addr, me->addrlen);
 327                   s->proto= pkt6->ip6_hdr.nxthdr;
 328                   if (s->proto == 0x11)
 329                     {
 330                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_UDP;
 331                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 332                               ntohs (pkt6_udp->udp_hdr.len));
 333                       app_type = GNUNET_APPLICATION_TYPE_INTERNET_UDP_GATEWAY;
 334                       if (NULL != udp_tunnel)
 335                         me->tunnel = udp_tunnel;
 336                     }
 337                   else if (s->proto == 0x06)
 338                     {
 339                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_TCP;
 340                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 341                               ntohs (pkt6->ip6_hdr.paylgth));
 342                       app_type = GNUNET_APPLICATION_TYPE_INTERNET_TCP_GATEWAY;
 343                       if (NULL != tcp_tunnel)
 344                         me->tunnel = tcp_tunnel;
 345                     }
 346                   if (me->tunnel == NULL && NULL != cls)
 347                     {
 348                       *cls = GNUNET_MESH_peer_request_connect_by_type(mesh_handle,
 349                                                                       GNUNET_TIME_UNIT_FOREVER_REL,
 350                                                                       app_type,
 351                                                                       send_pkt_to_peer,
 352                                                                       NULL,
 353                                                                       cls);
 354                       me->tunnel = *cls;
 355                       if (GNUNET_APPLICATION_TYPE_INTERNET_UDP_GATEWAY == app_type)
 356                         udp_tunnel = *cls;
 357                       else if (GNUNET_APPLICATION_TYPE_INTERNET_TCP_GATEWAY == app_type)
 358                         tcp_tunnel = *cls;
 359                     }
 360                   else if (NULL != cls)
 361                     {
 362                       *cls = me->tunnel;
 363                       send_pkt_to_peer(cls, (struct GNUNET_PeerIdentity*) 1, NULL);
 364                     }
 365                 }
 366             }
 367           break;
 368         case 0x3a:
 369           /* ICMPv6 */
 370           pkt6_icmp = (struct ip6_icmp *) pkt6;
 371           /* If this packet is an icmp-echo-request and a mapping exists, answer */
 372           if (pkt6_icmp->icmp_hdr.type == 0x80
 373               && (key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 374             {
 375               GNUNET_free (key);
 376               pkt6_icmp = GNUNET_malloc (ntohs (pkt6->shdr.size));
 377               memcpy (pkt6_icmp, pkt6, ntohs (pkt6->shdr.size));
 378               GNUNET_SCHEDULER_add_now (&send_icmp_response, pkt6_icmp);
 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 =
 395             sizeof (struct query_packet) + ntohs (udp->udp_hdr.len) - 9;
 396
 397           struct query_packet_list *query =
 398             GNUNET_malloc (len + 2 * sizeof (struct query_packet_list *));
 399           query->pkt.hdr.type = htons (GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 400           query->pkt.hdr.size = htons (len);
 401           query->pkt.orig_to = pkt->ip_hdr.dadr;
 402           query->pkt.orig_from = pkt->ip_hdr.sadr;
 403           query->pkt.src_port = udp->udp_hdr.spt;
 404           memcpy (query->pkt.data, udp->data, ntohs (udp->udp_hdr.len) - 8);
 405
 406           GNUNET_CONTAINER_DLL_insert_after (head, tail, tail, query);
 407
 408           GNUNET_assert (head != NULL);
 409
 410           if (dns_connection != NULL)
 411             GNUNET_CLIENT_notify_transmit_ready (dns_connection,
 412                                                  len,
 413                                                  GNUNET_TIME_UNIT_FOREVER_REL,
 414                                                  GNUNET_YES,
 415                                                  &send_query, NULL);
 416         }
 417     }
 418 }
 419
 420 void write_to_helper(void* buf, size_t len)
 421 {
 422   (void)GNUNET_DISK_file_write(helper_handle->fh_to_helper, buf, len);
 423 }
 424
 425 void schedule_helper_write(struct GNUNET_TIME_Relative time, void* cls)
 426 {
 427   if (GNUNET_SCHEDULER_NO_TASK == shs_task) return;
 428   GNUNET_SCHEDULER_add_write_file (time, helper_handle->fh_to_helper, &helper_write, cls);
 429 }