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 /*}}}*/
 131
 132 /**
 133  * Send an dns-answer-packet to the helper
 134  */
 135 void
 136 helper_write(void* cls __attribute__((unused)), 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 __attribute__((unused)),
 210                void *client __attribute__((unused)), 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               GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "me->addrlen is %d\n", me->addrlen);
 256               if (me->addrlen == 0)
 257                 {
 258                   /* This is a mapping to a gnunet-service */
 259                   memcpy (hc, &me->desc.service_descriptor,
 260                           sizeof (GNUNET_HashCode));
 261
 262                   if (0x11 == pkt6->ip6_hdr.nxthdr
 263                       && (me->desc.
 264                           service_type & htonl (GNUNET_DNS_SERVICE_TYPE_UDP))
 265                       && (port_in_ports (me->desc.ports, pkt6_udp->udp_hdr.dpt)
 266                           || testBit (me->additional_ports,
 267                                       ntohs (pkt6_udp->udp_hdr.dpt))))
 268                     {
 269                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_UDP);
 270
 271                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 272                               ntohs (pkt6_udp->udp_hdr.len));
 273
 274                     }
 275                   else if (0x06 == pkt6->ip6_hdr.nxthdr
 276                            && (me->desc.
 277                                service_type & htonl (GNUNET_DNS_SERVICE_TYPE_TCP))
 278                            &&
 279                            (port_in_ports (me->desc.ports, pkt6_tcp->tcp_hdr.dpt)))
 280                     {
 281                       hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_TCP);
 282
 283                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 284                               ntohs (pkt6->ip6_hdr.paylgth));
 285
 286                     }
 287                   if (me->tunnel == NULL && NULL != cls)
 288                     {
 289                       *cls =
 290                         GNUNET_MESH_peer_request_connect_all (mesh_handle,
 291                                                               GNUNET_TIME_UNIT_FOREVER_REL,
 292                                                               1,
 293                                                               (struct
 294                                                                GNUNET_PeerIdentity
 295                                                                *) &me->desc.peer,
 296                                                               send_pkt_to_peer,
 297                                                               NULL, cls);
 298                       me->tunnel = *cls;
 299                     }
 300                   else if (NULL != cls)
 301                     {
 302                       *cls = me->tunnel;
 303                       send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1,
 304                                         NULL);
 305                       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 306                                   "Queued to send to peer %x, type %d\n",
 307                                   *((unsigned int *) &me->desc.peer), ntohs(hdr->type));
 308                     }
 309                 }
 310               else
 311                 {
 312                   /* This is a mapping to a "real" address */
 313                   struct remote_addr *s = (struct remote_addr*) hc;
 314                   s->addrlen = me->addrlen;
 315                   memcpy(s->addr, me->addr, me->addrlen);
 316                   s->proto= pkt6->ip6_hdr.nxthdr;
 317                   if (s->proto == 0x11)
 318                     {
 319                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_UDP;
 320                       memcpy (hc + 1, &pkt6_udp->udp_hdr,
 321                               ntohs (pkt6_udp->udp_hdr.len));
 322                       app_type = GNUNET_APPLICATION_TYPE_INTERNET_UDP_GATEWAY;
 323                     }
 324                   else if (s->proto == 0x06)
 325                     {
 326                       hdr->type = GNUNET_MESSAGE_TYPE_REMOTE_TCP;
 327                       memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 328                               ntohs (pkt6->ip6_hdr.paylgth));
 329                       if (ntohs(pkt6_tcp->tcp_hdr.dpt) == 443)
 330                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_HTTPS_GATEWAY;
 331                       else if (ntohs(pkt6_tcp->tcp_hdr.dpt) == 80)
 332                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_HTTP_GATEWAY;
 333                       else
 334                         app_type = GNUNET_APPLICATION_TYPE_INTERNET_TCP_GATEWAY;
 335                     }
 336                   if (me->tunnel == NULL && NULL != cls)
 337                     {
 338                       *cls = GNUNET_MESH_peer_request_connect_by_type(mesh_handle,
 339                                                                       GNUNET_TIME_UNIT_FOREVER_REL,
 340                                                                       app_type,
 341                                                                       send_pkt_to_peer,
 342                                                                       NULL,
 343                                                                       cls);
 344                       me->tunnel = *cls;
 345                     }
 346                   else if (NULL != cls)
 347                     {
 348                       *cls = me->tunnel;
 349                       send_pkt_to_peer(cls, (struct GNUNET_PeerIdentity*) 1, NULL);
 350                     }
 351                 }
 352             }
 353           break;
 354         case 0x3a:
 355           /* ICMPv6 */
 356           pkt6_icmp = (struct ip6_icmp *) pkt6;
 357           /* If this packet is an icmp-echo-request and a mapping exists, answer */
 358           if (pkt6_icmp->icmp_hdr.type == 0x80
 359               && (key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 360             {
 361               GNUNET_free (key);
 362               pkt6_icmp = GNUNET_malloc (ntohs (pkt6->shdr.size));
 363               memcpy (pkt6_icmp, pkt6, ntohs (pkt6->shdr.size));
 364               GNUNET_SCHEDULER_add_now (&send_icmp_response, pkt6_icmp);
 365             }
 366           break;
 367         }
 368     }
 369   /* ethertype is ipv4 */
 370   else if (ntohs (pkt_tun->tun.type) == 0x0800)
 371     {
 372       struct ip_pkt *pkt = (struct ip_pkt *) message;
 373       struct ip_udp *udp = (struct ip_udp *) message;
 374       GNUNET_assert (pkt->ip_hdr.version == 4);
 375
 376       /* Send dns-packets to the service-dns */
 377       if (pkt->ip_hdr.proto == 0x11 && ntohs (udp->udp_hdr.dpt) == 53)
 378         {
 379           /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 380           size_t len =
 381             sizeof (struct query_packet) + ntohs (udp->udp_hdr.len) - 9;
 382
 383           struct query_packet_list *query =
 384             GNUNET_malloc (len + 2 * sizeof (struct query_packet_list *));
 385           query->pkt.hdr.type = htons (GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 386           query->pkt.hdr.size = htons (len);
 387           query->pkt.orig_to = pkt->ip_hdr.dadr;
 388           query->pkt.orig_from = pkt->ip_hdr.sadr;
 389           query->pkt.src_port = udp->udp_hdr.spt;
 390           memcpy (query->pkt.data, udp->data, ntohs (udp->udp_hdr.len) - 8);
 391
 392           GNUNET_CONTAINER_DLL_insert_after (head, tail, tail, query);
 393
 394           GNUNET_assert (head != NULL);
 395
 396           if (dns_connection != NULL)
 397             GNUNET_CLIENT_notify_transmit_ready (dns_connection,
 398                                                  len,
 399                                                  GNUNET_TIME_UNIT_FOREVER_REL,
 400                                                  GNUNET_YES,
 401                                                  &send_query, NULL);
 402         }
 403     }
 404 }
 405
 406 void write_to_helper(void* buf, size_t len)
 407 {
 408   (void)GNUNET_DISK_file_write(helper_handle->fh_to_helper, buf, len);
 409 }
 410
 411 void schedule_helper_write(struct GNUNET_TIME_Relative time, void* cls)
 412 {
 413   GNUNET_SCHEDULER_add_write_file (time, helper_handle->fh_to_helper, &helper_write, cls);
 414 }