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  * Start the helper-process
  50  *
  51  * If cls != NULL it is assumed that this function is called as a result of a dying
  52  * helper. cls is then taken as handle to the old helper and is cleaned up.
  53  * {{{
  54  */
  55 void
  56 start_helper_and_schedule(void *cls,
  57                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
  58     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
  59       return;
  60
  61     if (cls != NULL)
  62       cleanup_helper(cls);
  63     cls = NULL;
  64
  65     char* ifname;
  66     char* ipv6addr;
  67     char* ipv6prefix;
  68     char* ipv4addr;
  69     char* ipv4mask;
  70
  71     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IFNAME", &ifname))
  72       {
  73         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IFNAME' in configuration!\n");
  74         exit(1);
  75       }
  76
  77     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6ADDR", &ipv6addr))
  78       {
  79         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6ADDR' in configuration!\n");
  80         exit(1);
  81       }
  82
  83     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6PREFIX", &ipv6prefix))
  84       {
  85         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6PREFIX' in configuration!\n");
  86         exit(1);
  87       }
  88
  89     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4ADDR", &ipv4addr))
  90       {
  91         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4ADDR' in configuration!\n");
  92         exit(1);
  93       }
  94
  95     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4MASK", &ipv4mask))
  96       {
  97         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4MASK' in configuration!\n");
  98         exit(1);
  99       }
 100
 101     /* Start the helper
 102      * Messages get passed to the function message_token
 103      * When the helper dies, this function will be called again with the
 104      * helper_handle as cls.
 105      */
 106     helper_handle = start_helper(ifname,
 107                                  ipv6addr,
 108                                  ipv6prefix,
 109                                  ipv4addr,
 110                                  ipv4mask,
 111                                  "vpn-gnunet",
 112                                  start_helper_and_schedule,
 113                                  message_token,
 114                                  NULL,
 115                                  NULL);
 116
 117     GNUNET_free(ipv6addr);
 118     GNUNET_free(ipv6prefix);
 119     GNUNET_free(ipv4addr);
 120     GNUNET_free(ipv4mask);
 121     GNUNET_free(ifname);
 122
 123     /* Tell the dns-service to rehijack the dns-port
 124      * The routing-table gets flushed if an interface disappears.
 125      */
 126     restart_hijack = 1;
 127     if (NULL != dns_connection)
 128       GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 129 }
 130 /*}}}*/
 131
 132 /**
 133  * Send an dns-answer-packet to the helper
 134  */
 135 void
 136 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 137     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 138       return;
 139
 140     struct answer_packet_list* ans = answer_proc_head;
 141     size_t len = ntohs(ans->pkt.hdr.size);
 142
 143     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 144
 145     GNUNET_assert (20 == sizeof (struct ip_hdr));
 146     GNUNET_assert (8 == sizeof (struct udp_pkt));
 147     size_t data_len = len - sizeof(struct answer_packet) + 1;
 148     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 149     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 150
 151     struct ip_udp_dns* pkt = alloca(pkt_len);
 152     GNUNET_assert(pkt != NULL);
 153     memset(pkt, 0, pkt_len);
 154
 155     /* set the gnunet-header */
 156     pkt->shdr.size = htons(pkt_len);
 157     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 158
 159     /* set the tun-header (no flags and ethertype of IPv4) */
 160     pkt->tun.flags = 0;
 161     pkt->tun.type = htons(0x0800);
 162
 163     /* set the ip-header */
 164     pkt->ip_hdr.version = 4;
 165     pkt->ip_hdr.hdr_lngth = 5;
 166     pkt->ip_hdr.diff_serv = 0;
 167     pkt->ip_hdr.tot_lngth = htons(net_len);
 168     pkt->ip_hdr.ident = 0;
 169     pkt->ip_hdr.flags = 0;
 170     pkt->ip_hdr.frag_off = 0;
 171     pkt->ip_hdr.ttl = 255;
 172     pkt->ip_hdr.proto = 0x11; /* UDP */
 173     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 174     pkt->ip_hdr.sadr = ans->pkt.from;
 175     pkt->ip_hdr.dadr = ans->pkt.to;
 176
 177     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 178
 179     /* set the udp-header */
 180     pkt->udp_dns.udp_hdr.spt = htons(53);
 181     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 182     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 183     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 184
 185     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 186
 187     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 188     GNUNET_free(ans);
 189
 190     if (GNUNET_DISK_file_write(helper_handle->fh_to_helper, pkt, pkt_len) < 0)
 191       {
 192         cleanup_helper(helper_handle);
 193         GNUNET_SCHEDULER_add_now(start_helper_and_schedule, NULL);
 194         return;
 195       }
 196
 197     /* if more packets are available, reschedule */
 198     if (answer_proc_head != NULL)
 199       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 200                                        helper_handle->fh_to_helper,
 201                                        &helper_write,
 202                                        NULL);
 203 }
 204
 205 /**
 206  * Receive packets from the helper-process
 207  */
 208 void
 209 message_token (void *cls,
 210                void *client, const struct GNUNET_MessageHeader *message)
 211 {
 212   GNUNET_assert (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 213
 214   struct tun_pkt *pkt_tun = (struct tun_pkt *) message;
 215
 216   /* ethertype is ipv6 */
 217   if (ntohs (pkt_tun->tun.type) == 0x86dd)
 218     {
 219       struct ip6_pkt *pkt6 = (struct ip6_pkt *) message;
 220       GNUNET_assert (pkt6->ip6_hdr.version == 6);
 221       struct ip6_tcp *pkt6_tcp;
 222       struct ip6_udp *pkt6_udp;
 223       struct ip6_icmp *pkt6_icmp;
 224       GNUNET_HashCode *key;
 225
 226       switch (pkt6->ip6_hdr.nxthdr)
 227         {
 228         case 0x06:             /* TCP */
 229         case 0x11:             /* UDP */
 230           pkt6_tcp = (struct ip6_tcp *) pkt6;
 231           pkt6_udp = (struct ip6_udp *) pkt6;
 232
 233           if ((key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 234             {
 235               struct map_entry *me =
 236                 GNUNET_CONTAINER_multihashmap_get (hashmap, key);
 237               GNUNET_assert (me != NULL);
 238               GNUNET_free (key);
 239
 240               size_t size =
 241                 sizeof (struct GNUNET_MESH_Tunnel *) +
 242                 sizeof (struct GNUNET_MessageHeader) +
 243                 sizeof (GNUNET_HashCode) + ntohs (pkt6->ip6_hdr.paylgth);
 244
 245               struct GNUNET_MESH_Tunnel **cls = GNUNET_malloc (size);
 246               struct GNUNET_MessageHeader *hdr =
 247                 (struct GNUNET_MessageHeader *) (cls + 1);
 248               GNUNET_HashCode *hc = (GNUNET_HashCode *) (hdr + 1);
 249
 250               hdr->size = htons (sizeof (struct GNUNET_MessageHeader) +
 251                                  sizeof (GNUNET_HashCode) +
 252                                  ntohs (pkt6->ip6_hdr.paylgth));
 253
 254               GNUNET_MESH_ApplicationType app_type;
 255               if (me->addrlen == 0)
 256                 {
 257                   /* This is a mapping to a gnunet-service */
 258                   memcpy (hc, &me->desc.service_descriptor,
 259                           sizeof (GNUNET_HashCode));
 260
 261                   if (0x11 == pkt6->ip6_hdr.nxthdr
 262                       && (me->desc.
 263                           service_type & htonl (GNUNET_DNS_SERVICE_TYPE_UDP))
 264                       && (port_in_ports (me->desc.ports, pkt6_udp->udp_hdr.dpt)
 265                           || testBit (me->additional_ports,
 266                                       ntohs (pkt6_udp->udp_hdr.dpt))))
 267                     {
 268                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_UDP);
 269
 270                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 271                               ntohs (pkt6_udp->udp_hdr.len));
 272
 273                     }
 274                   else if (0x06 == pkt6->ip6_hdr.nxthdr
 275                            && (me->desc.
 276                                service_type & htonl (GNUNET_DNS_SERVICE_TYPE_TCP))
 277                            &&
 278                            (port_in_ports (me->desc.ports, pkt6_tcp->tcp_hdr.dpt)))
 279                     {
 280                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_TCP);
 281
 282                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 283                               ntohs (pkt6->ip6_hdr.paylgth));
 284
 285                     }
 286                   if (me->tunnel == NULL && NULL != cls)
 287                     {
 288                       *cls =
 289                         GNUNET_MESH_peer_request_connect_all (mesh_handle,
 290                                                               GNUNET_TIME_UNIT_FOREVER_REL,
 291                                                               1,
 292                                                               (struct
 293                                                                GNUNET_PeerIdentity
 294                                                                *) &me->desc.peer,
 295                                                               send_pkt_to_peer,
 296                                                               NULL, cls);
 297                       me->tunnel = *cls;
 298                     }
 299                   else if (NULL != cls)
 300                     {
 301                       *cls = me->tunnel;
 302                       send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1,
 303                                         NULL);
 304                       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 305                                   "Queued to send to peer %x, type %d\n",
 306                                   *((unsigned int *) &me->desc.peer), ntohs(hdr->type));
 307                     }
 308                 }
 309               else
 310                 {
 311                   /* This is a mapping to a "real" address */
 312                   struct remote_addr *s = (struct remote_addr*) hc;
 313                   s->addrlen = me->addrlen;
 314                   memcpy(s->addr, me->addr, me->addrlen);
 315                   s->proto= pkt6->ip6_hdr.nxthdr;
 316                   if (s->proto == 0x11)
 317                     {
 318                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_UDP;
 319                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 320                               ntohs (pkt6_udp->udp_hdr.len));
 321                       app_type = GNUNET_APPLICATION_TYPE_INTERNET_UDP_GATEWAY;
 322                     }
 323                   else if (s->proto == 0x06)
 324                     {
 325                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_TCP;
 326                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 327                               ntohs (pkt6->ip6_hdr.paylgth));
 328                       if (ntohs(pkt6_tcp->tcp_hdr.dpt) == 443)
 329                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_HTTPS_GATEWAY;
 330                       else if (ntohs(pkt6_tcp->tcp_hdr.dpt) == 80)
 331                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_HTTP_GATEWAY;
 332                       else
 333                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_TCP_GATEWAY;
 334                     }
 335                   if (me->tunnel == NULL && NULL != cls)
 336                     {
 337                       *cls = GNUNET_MESH_peer_request_connect_by_type(mesh_handle,
 338                                                                       GNUNET_TIME_UNIT_FOREVER_REL,
 339                                                                       app_type,
 340                                                                       send_pkt_to_peer,
 341                                                                       NULL,
 342                                                                       cls);
 343                       me->tunnel = *cls;
 344                     }
 345                   else if (NULL != cls)
 346                     {
 347                       *cls = me->tunnel;
 348                       send_pkt_to_peer(cls, (struct GNUNET_PeerIdentity*) 1, NULL);
 349                     }
 350                 }
 351             }
 352           break;
 353         case 0x3a:
 354           /* ICMPv6 */
 355           pkt6_icmp = (struct ip6_icmp *) pkt6;
 356           /* If this packet is an icmp-echo-request and a mapping exists, answer */
 357           if (pkt6_icmp->icmp_hdr.type == 0x80
 358               && (key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 359             {
 360               GNUNET_free (key);
 361               pkt6_icmp = GNUNET_malloc (ntohs (pkt6->shdr.size));
 362               memcpy (pkt6_icmp, pkt6, ntohs (pkt6->shdr.size));
 363               GNUNET_SCHEDULER_add_now (&send_icmp_response, pkt6_icmp);
 364             }
 365           break;
 366         }
 367     }
 368   /* ethertype is ipv4 */
 369   else if (ntohs (pkt_tun->tun.type) == 0x0800)
 370     {
 371       struct ip_pkt *pkt = (struct ip_pkt *) message;
 372       struct ip_udp *udp = (struct ip_udp *) message;
 373       GNUNET_assert (pkt->ip_hdr.version == 4);
 374
 375       /* Send dns-packets to the service-dns */
 376       if (pkt->ip_hdr.proto == 0x11 && ntohs (udp->udp_hdr.dpt) == 53)
 377         {
 378           /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 379           size_t len =
 380             sizeof (struct query_packet) + ntohs (udp->udp_hdr.len) - 9;
 381
 382           struct query_packet_list *query =
 383             GNUNET_malloc (len + 2 * sizeof (struct query_packet_list *));
 384           query->pkt.hdr.type = htons (GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 385           query->pkt.hdr.size = htons (len);
 386           query->pkt.orig_to = pkt->ip_hdr.dadr;
 387           query->pkt.orig_from = pkt->ip_hdr.sadr;
 388           query->pkt.src_port = udp->udp_hdr.spt;
 389           memcpy (query->pkt.data, udp->data, ntohs (udp->udp_hdr.len) - 8);
 390
 391           GNUNET_CONTAINER_DLL_insert_after (head, tail, tail, query);
 392
 393           GNUNET_assert (head != NULL);
 394
 395           if (dns_connection != NULL)
 396             GNUNET_CLIENT_notify_transmit_ready (dns_connection,
 397                                                  len,
 398                                                  GNUNET_TIME_UNIT_FOREVER_REL,
 399                                                  GNUNET_YES,
 400                                                  &send_query, NULL);
 401         }
 402     }
 403 }
 404
 405 void write_to_helper(void* buf, size_t len)
 406 {
 407   (void)GNUNET_DISK_file_write(helper_handle->fh_to_helper, buf, len);
 408 }
 409
 410 void schedule_helper_write(struct GNUNET_TIME_Relative time, void* cls)
 411 {
 412   GNUNET_SCHEDULER_add_write_file (time, helper_handle->fh_to_helper, &helper_write, cls);
 413 }