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   shs_task = GNUNET_SCHEDULER_NO_TASK;
  59     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
  60       return;
  61
  62     if (cls != NULL)
  63       cleanup_helper(cls);
  64     cls = NULL;
  65
  66     char* ifname;
  67     char* ipv6addr;
  68     char* ipv6prefix;
  69     char* ipv4addr;
  70     char* ipv4mask;
  71
  72     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IFNAME", &ifname))
  73       {
  74         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IFNAME' in configuration!\n");
  75         exit(1);
  76       }
  77
  78     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6ADDR", &ipv6addr))
  79       {
  80         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6ADDR' in configuration!\n");
  81         exit(1);
  82       }
  83
  84     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6PREFIX", &ipv6prefix))
  85       {
  86         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6PREFIX' in configuration!\n");
  87         exit(1);
  88       }
  89
  90     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4ADDR", &ipv4addr))
  91       {
  92         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4ADDR' in configuration!\n");
  93         exit(1);
  94       }
  95
  96     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4MASK", &ipv4mask))
  97       {
  98         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4MASK' in configuration!\n");
  99         exit(1);
 100       }
 101
 102     /* Start the helper
 103      * Messages get passed to the function message_token
 104      * When the helper dies, this function will be called again with the
 105      * helper_handle as cls.
 106      */
 107     helper_handle = start_helper(ifname,
 108                                  ipv6addr,
 109                                  ipv6prefix,
 110                                  ipv4addr,
 111                                  ipv4mask,
 112                                  "vpn-gnunet",
 113                                  start_helper_and_schedule,
 114                                  message_token,
 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     GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL, helper_handle->fh_to_helper, &helper_write, NULL);
 131 }
 132 /*}}}*/
 133
 134 /**
 135  * Send an dns-answer-packet to the helper
 136  */
 137 void
 138 helper_write(void* cls __attribute__((unused)), const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 139     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 140       return;
 141
 142     struct answer_packet_list* ans = answer_proc_head;
 143
 144     if (NULL == ans) return;
 145
 146     size_t len = ntohs(ans->pkt.hdr.size);
 147
 148     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 149
 150     GNUNET_assert (20 == sizeof (struct ip_hdr));
 151     GNUNET_assert (8 == sizeof (struct udp_pkt));
 152     size_t data_len = len - sizeof(struct answer_packet) + 1;
 153     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 154     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 155
 156     struct ip_udp_dns* pkt = alloca(pkt_len);
 157     GNUNET_assert(pkt != NULL);
 158     memset(pkt, 0, pkt_len);
 159
 160     /* set the gnunet-header */
 161     pkt->shdr.size = htons(pkt_len);
 162     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 163
 164     /* set the tun-header (no flags and ethertype of IPv4) */
 165     pkt->tun.flags = 0;
 166     pkt->tun.type = htons(0x0800);
 167
 168     /* set the ip-header */
 169     pkt->ip_hdr.version = 4;
 170     pkt->ip_hdr.hdr_lngth = 5;
 171     pkt->ip_hdr.diff_serv = 0;
 172     pkt->ip_hdr.tot_lngth = htons(net_len);
 173     pkt->ip_hdr.ident = 0;
 174     pkt->ip_hdr.flags = 0;
 175     pkt->ip_hdr.frag_off = 0;
 176     pkt->ip_hdr.ttl = 255;
 177     pkt->ip_hdr.proto = 0x11; /* UDP */
 178     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 179     pkt->ip_hdr.sadr = ans->pkt.from;
 180     pkt->ip_hdr.dadr = ans->pkt.to;
 181
 182     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 183
 184     /* set the udp-header */
 185     pkt->udp_dns.udp_hdr.spt = htons(53);
 186     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 187     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 188     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 189
 190     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 191
 192     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 193     GNUNET_free(ans);
 194
 195     if (GNUNET_DISK_file_write(helper_handle->fh_to_helper, pkt, pkt_len) < 0)
 196       {
 197         cleanup_helper(helper_handle);
 198         GNUNET_SCHEDULER_add_now(start_helper_and_schedule, NULL);
 199         return;
 200       }
 201
 202     /* if more packets are available, reschedule */
 203     if (answer_proc_head != NULL)
 204       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 205                                        helper_handle->fh_to_helper,
 206                                        &helper_write,
 207                                        NULL);
 208 }
 209
 210 /**
 211  * Receive packets from the helper-process
 212  */
 213 void
 214 message_token (void *cls __attribute__((unused)),
 215                void *client __attribute__((unused)), const struct GNUNET_MessageHeader *message)
 216 {
 217   GNUNET_assert (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 218
 219   struct tun_pkt *pkt_tun = (struct tun_pkt *) message;
 220
 221   /* ethertype is ipv6 */
 222   if (ntohs (pkt_tun->tun.type) == 0x86dd)
 223     {
 224       struct ip6_pkt *pkt6 = (struct ip6_pkt *) message;
 225       GNUNET_assert (pkt6->ip6_hdr.version == 6);
 226       struct ip6_tcp *pkt6_tcp;
 227       struct ip6_udp *pkt6_udp;
 228       struct ip6_icmp *pkt6_icmp;
 229       GNUNET_HashCode *key;
 230
 231       switch (pkt6->ip6_hdr.nxthdr)
 232         {
 233         case 0x06:             /* TCP */
 234         case 0x11:             /* UDP */
 235           pkt6_tcp = (struct ip6_tcp *) pkt6;
 236           pkt6_udp = (struct ip6_udp *) pkt6;
 237
 238           if ((key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 239             {
 240               struct map_entry *me =
 241                 GNUNET_CONTAINER_multihashmap_get (hashmap, key);
 242               GNUNET_assert (me != NULL);
 243               GNUNET_free (key);
 244
 245               size_t size =
 246                 sizeof (struct GNUNET_MESH_Tunnel *) +
 247                 sizeof (struct GNUNET_MessageHeader) +
 248                 sizeof (GNUNET_HashCode) + ntohs (pkt6->ip6_hdr.paylgth);
 249
 250               struct GNUNET_MESH_Tunnel **cls = GNUNET_malloc (size);
 251               struct GNUNET_MessageHeader *hdr =
 252                 (struct GNUNET_MessageHeader *) (cls + 1);
 253               GNUNET_HashCode *hc = (GNUNET_HashCode *) (hdr + 1);
 254
 255               hdr->size = htons (sizeof (struct GNUNET_MessageHeader) +
 256                                  sizeof (GNUNET_HashCode) +
 257                                  ntohs (pkt6->ip6_hdr.paylgth));
 258
 259               GNUNET_MESH_ApplicationType app_type;
 260               GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "me->addrlen is %d\n", me->addrlen);
 261               if (me->addrlen == 0)
 262                 {
 263                   /* This is a mapping to a gnunet-service */
 264                   memcpy (hc, &me->desc.service_descriptor,
 265                           sizeof (GNUNET_HashCode));
 266
 267                   if (0x11 == pkt6->ip6_hdr.nxthdr
 268                       && (me->desc.
 269                           service_type & htonl (GNUNET_DNS_SERVICE_TYPE_UDP))
 270                       && (port_in_ports (me->desc.ports, pkt6_udp->udp_hdr.dpt)
 271                           || testBit (me->additional_ports,
 272                                       ntohs (pkt6_udp->udp_hdr.dpt))))
 273                     {
 274                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_UDP);
 275
 276                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 277                               ntohs (pkt6_udp->udp_hdr.len));
 278
 279                     }
 280                   else if (0x06 == pkt6->ip6_hdr.nxthdr
 281                            && (me->desc.
 282                                service_type & htonl (GNUNET_DNS_SERVICE_TYPE_TCP))
 283                            &&
 284                            (port_in_ports (me->desc.ports, pkt6_tcp->tcp_hdr.dpt)))
 285                     {
 286                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_TCP);
 287
 288                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 289                               ntohs (pkt6->ip6_hdr.paylgth));
 290
 291                     }
 292                   if (me->tunnel == NULL && NULL != cls)
 293                     {
 294                       *cls =
 295                         GNUNET_MESH_peer_request_connect_all (mesh_handle,
 296                                                               GNUNET_TIME_UNIT_FOREVER_REL,
 297                                                               1,
 298                                                               (struct
 299                                                                GNUNET_PeerIdentity
 300                                                                *) &me->desc.peer,
 301                                                               send_pkt_to_peer,
 302                                                               NULL, cls);
 303                       me->tunnel = *cls;
 304                     }
 305                   else if (NULL != cls)
 306                     {
 307                       *cls = me->tunnel;
 308                       send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1,
 309                                         NULL);
 310                       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 311                                   "Queued to send to peer %x, type %d\n",
 312                                   *((unsigned int *) &me->desc.peer), ntohs(hdr->type));
 313                     }
 314                 }
 315               else
 316                 {
 317                   /* This is a mapping to a "real" address */
 318                   struct remote_addr *s = (struct remote_addr*) hc;
 319                   s->addrlen = me->addrlen;
 320                   memcpy(s->addr, me->addr, me->addrlen);
 321                   s->proto= pkt6->ip6_hdr.nxthdr;
 322                   if (s->proto == 0x11)
 323                     {
 324                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_UDP;
 325                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 326                               ntohs (pkt6_udp->udp_hdr.len));
 327                       app_type = GNUNET_APPLICATION_TYPE_INTERNET_UDP_GATEWAY;
 328                     }
 329                   else if (s->proto == 0x06)
 330                     {
 331                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_TCP;
 332                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 333                               ntohs (pkt6->ip6_hdr.paylgth));
 334                       if (ntohs(pkt6_tcp->tcp_hdr.dpt) == 443)
 335                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_HTTPS_GATEWAY;
 336                       else if (ntohs(pkt6_tcp->tcp_hdr.dpt) == 80)
 337                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_HTTP_GATEWAY;
 338                       else
 339                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_TCP_GATEWAY;
 340                     }
 341                   if (me->tunnel == NULL && NULL != cls)
 342                     {
 343                       *cls = GNUNET_MESH_peer_request_connect_by_type(mesh_handle,
 344                                                                       GNUNET_TIME_UNIT_FOREVER_REL,
 345                                                                       app_type,
 346                                                                       send_pkt_to_peer,
 347                                                                       NULL,
 348                                                                       cls);
 349                       me->tunnel = *cls;
 350                     }
 351                   else if (NULL != cls)
 352                     {
 353                       *cls = me->tunnel;
 354                       send_pkt_to_peer(cls, (struct GNUNET_PeerIdentity*) 1, NULL);
 355                     }
 356                 }
 357             }
 358           break;
 359         case 0x3a:
 360           /* ICMPv6 */
 361           pkt6_icmp = (struct ip6_icmp *) pkt6;
 362           /* If this packet is an icmp-echo-request and a mapping exists, answer */
 363           if (pkt6_icmp->icmp_hdr.type == 0x80
 364               && (key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 365             {
 366               GNUNET_free (key);
 367               pkt6_icmp = GNUNET_malloc (ntohs (pkt6->shdr.size));
 368               memcpy (pkt6_icmp, pkt6, ntohs (pkt6->shdr.size));
 369               GNUNET_SCHEDULER_add_now (&send_icmp_response, pkt6_icmp);
 370             }
 371           break;
 372         }
 373     }
 374   /* ethertype is ipv4 */
 375   else if (ntohs (pkt_tun->tun.type) == 0x0800)
 376     {
 377       struct ip_pkt *pkt = (struct ip_pkt *) message;
 378       struct ip_udp *udp = (struct ip_udp *) message;
 379       GNUNET_assert (pkt->ip_hdr.version == 4);
 380
 381       /* Send dns-packets to the service-dns */
 382       if (pkt->ip_hdr.proto == 0x11 && ntohs (udp->udp_hdr.dpt) == 53)
 383         {
 384           /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 385           size_t len =
 386             sizeof (struct query_packet) + ntohs (udp->udp_hdr.len) - 9;
 387
 388           struct query_packet_list *query =
 389             GNUNET_malloc (len + 2 * sizeof (struct query_packet_list *));
 390           query->pkt.hdr.type = htons (GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 391           query->pkt.hdr.size = htons (len);
 392           query->pkt.orig_to = pkt->ip_hdr.dadr;
 393           query->pkt.orig_from = pkt->ip_hdr.sadr;
 394           query->pkt.src_port = udp->udp_hdr.spt;
 395           memcpy (query->pkt.data, udp->data, ntohs (udp->udp_hdr.len) - 8);
 396
 397           GNUNET_CONTAINER_DLL_insert_after (head, tail, tail, query);
 398
 399           GNUNET_assert (head != NULL);
 400
 401           if (dns_connection != NULL)
 402             GNUNET_CLIENT_notify_transmit_ready (dns_connection,
 403                                                  len,
 404                                                  GNUNET_TIME_UNIT_FOREVER_REL,
 405                                                  GNUNET_YES,
 406                                                  &send_query, NULL);
 407         }
 408     }
 409 }
 410
 411 void write_to_helper(void* buf, size_t len)
 412 {
 413   (void)GNUNET_DISK_file_write(helper_handle->fh_to_helper, buf, len);
 414 }
 415
 416 void schedule_helper_write(struct GNUNET_TIME_Relative time, void* cls)
 417 {
 418   if (GNUNET_SCHEDULER_NO_TASK == shs_task) return;
 419   GNUNET_SCHEDULER_add_write_file (time, helper_handle->fh_to_helper, &helper_write, cls);
 420 }