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
  37 #include "gnunet-daemon-vpn-dns.h"
  38 #include "gnunet-daemon-vpn.h"
  39 #include "gnunet-daemon-vpn-helper.h"
  40 #include "gnunet-service-dns-p.h"
  41 #include "gnunet-vpn-packet.h"
  42 #include "gnunet-vpn-checksum.h"
  43 #include "gnunet-helper-vpn-api.h"
  44
  45 struct GNUNET_VPN_HELPER_Handle *helper_handle;
  46
  47 /**
  48  * Start the helper-process
  49  *
  50  * If cls != NULL it is assumed that this function is called as a result of a dying
  51  * helper. cls is then taken as handle to the old helper and is cleaned up.
  52  * {{{
  53  */
  54 void
  55 start_helper_and_schedule(void *cls,
  56                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
  57     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
  58       return;
  59
  60     if (cls != NULL)
  61       cleanup_helper(cls);
  62     cls = NULL;
  63
  64     char* ifname;
  65     char* ipv6addr;
  66     char* ipv6prefix;
  67     char* ipv4addr;
  68     char* ipv4mask;
  69
  70     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IFNAME", &ifname))
  71       {
  72         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IFNAME' in configuration!\n");
  73         exit(1);
  74       }
  75
  76     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6ADDR", &ipv6addr))
  77       {
  78         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6ADDR' in configuration!\n");
  79         exit(1);
  80       }
  81
  82     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV6PREFIX", &ipv6prefix))
  83       {
  84         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV6PREFIX' in configuration!\n");
  85         exit(1);
  86       }
  87
  88     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4ADDR", &ipv4addr))
  89       {
  90         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4ADDR' in configuration!\n");
  91         exit(1);
  92       }
  93
  94     if (GNUNET_SYSERR == GNUNET_CONFIGURATION_get_value_string(cfg, "vpn", "IPV4MASK", &ipv4mask))
  95       {
  96         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "No entry 'IPV4MASK' in configuration!\n");
  97         exit(1);
  98       }
  99
 100     /* Start the helper
 101      * Messages get passed to the function message_token
 102      * When the helper dies, this function will be called again with the
 103      * helper_handle as cls.
 104      */
 105     helper_handle = start_helper(ifname,
 106                                  ipv6addr,
 107                                  ipv6prefix,
 108                                  ipv4addr,
 109                                  ipv4mask,
 110                                  "vpn-gnunet",
 111                                  start_helper_and_schedule,
 112                                  message_token,
 113                                  NULL,
 114                                  NULL);
 115
 116     GNUNET_free(ipv6addr);
 117     GNUNET_free(ipv6prefix);
 118     GNUNET_free(ipv4addr);
 119     GNUNET_free(ipv4mask);
 120     GNUNET_free(ifname);
 121
 122     /* Tell the dns-service to rehijack the dns-port
 123      * The routing-table gets flushed if an interface disappears.
 124      */
 125     restart_hijack = 1;
 126     if (NULL != dns_connection)
 127       GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 128 }
 129 /*}}}*/
 130
 131 /**
 132  * Send an dns-answer-packet to the helper
 133  */
 134 void
 135 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 136     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 137       return;
 138
 139     struct answer_packet_list* ans = answer_proc_head;
 140     size_t len = ntohs(ans->pkt.hdr.size);
 141
 142     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 143
 144     GNUNET_assert (20 == sizeof (struct ip_hdr));
 145     GNUNET_assert (8 == sizeof (struct udp_pkt));
 146     size_t data_len = len - sizeof(struct answer_packet) + 1;
 147     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 148     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 149
 150     struct ip_udp_dns* pkt = alloca(pkt_len);
 151     GNUNET_assert(pkt != NULL);
 152     memset(pkt, 0, pkt_len);
 153
 154     /* set the gnunet-header */
 155     pkt->shdr.size = htons(pkt_len);
 156     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 157
 158     /* set the tun-header (no flags and ethertype of IPv4) */
 159     pkt->tun.flags = 0;
 160     pkt->tun.type = htons(0x0800);
 161
 162     /* set the ip-header */
 163     pkt->ip_hdr.version = 4;
 164     pkt->ip_hdr.hdr_lngth = 5;
 165     pkt->ip_hdr.diff_serv = 0;
 166     pkt->ip_hdr.tot_lngth = htons(net_len);
 167     pkt->ip_hdr.ident = 0;
 168     pkt->ip_hdr.flags = 0;
 169     pkt->ip_hdr.frag_off = 0;
 170     pkt->ip_hdr.ttl = 255;
 171     pkt->ip_hdr.proto = 0x11; /* UDP */
 172     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 173     pkt->ip_hdr.sadr = ans->pkt.from;
 174     pkt->ip_hdr.dadr = ans->pkt.to;
 175
 176     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 177
 178     /* set the udp-header */
 179     pkt->udp_dns.udp_hdr.spt = htons(53);
 180     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 181     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 182     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 183
 184     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 185
 186     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 187     GNUNET_free(ans);
 188
 189     if (GNUNET_DISK_file_write(helper_handle->fh_to_helper, pkt, pkt_len) < 0)
 190       {
 191         cleanup_helper(helper_handle);
 192         GNUNET_SCHEDULER_add_now(start_helper_and_schedule, NULL);
 193         return;
 194       }
 195
 196     /* if more packets are available, reschedule */
 197     if (answer_proc_head != NULL)
 198       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 199                                        helper_handle->fh_to_helper,
 200                                        &helper_write,
 201                                        NULL);
 202 }
 203
 204 /**
 205  * Receive packets from the helper-process
 206  */
 207 void
 208 message_token (void *cls,
 209                void *client, const struct GNUNET_MessageHeader *message)
 210 {
 211   GNUNET_assert (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 212
 213   struct tun_pkt *pkt_tun = (struct tun_pkt *) message;
 214
 215   /* ethertype is ipv6 */
 216   if (ntohs (pkt_tun->tun.type) == 0x86dd)
 217     {
 218       struct ip6_pkt *pkt6 = (struct ip6_pkt *) message;
 219       GNUNET_assert (pkt6->ip6_hdr.version == 6);
 220       struct ip6_tcp *pkt6_tcp;
 221       struct ip6_udp *pkt6_udp;
 222       struct ip6_icmp *pkt6_icmp;
 223       GNUNET_HashCode *key;
 224
 225       switch (pkt6->ip6_hdr.nxthdr)
 226         {
 227         case 0x06:             /* TCP */
 228         case 0x11:             /* UDP */
 229           pkt6_tcp = (struct ip6_tcp *) pkt6;
 230           pkt6_udp = (struct ip6_udp *) pkt6;
 231
 232           if ((key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 233             {
 234               struct map_entry *me =
 235                 GNUNET_CONTAINER_multihashmap_get (hashmap, key);
 236               GNUNET_assert (me != NULL);
 237               GNUNET_free (key);
 238
 239               size_t size =
 240                 sizeof (struct GNUNET_MESH_Tunnel *) +
 241                 sizeof (struct GNUNET_MessageHeader) +
 242                 sizeof (GNUNET_HashCode) + ntohs (pkt6->ip6_hdr.paylgth);
 243
 244               struct GNUNET_MESH_Tunnel **cls = GNUNET_malloc (size);
 245               struct GNUNET_MessageHeader *hdr =
 246                 (struct GNUNET_MessageHeader *) (cls + 1);
 247               GNUNET_HashCode *hc = (GNUNET_HashCode *) (hdr + 1);
 248
 249               hdr->size = htons (sizeof (struct GNUNET_MessageHeader) +
 250                                  sizeof (GNUNET_HashCode) +
 251                                  ntohs (pkt6->ip6_hdr.paylgth));
 252
 253               memcpy (hc, &me->desc.service_descriptor,
 254                       sizeof (GNUNET_HashCode));
 255
 256               if (0x11 == pkt6->ip6_hdr.nxthdr
 257                   && (me->desc.
 258                       service_type & htonl (GNUNET_DNS_SERVICE_TYPE_UDP))
 259                   && (port_in_ports (me->desc.ports, pkt6_udp->udp_hdr.dpt)
 260                       || testBit (me->additional_ports,
 261                                   ntohs (pkt6_udp->udp_hdr.dpt))))
 262                 {
 263                   hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_UDP);
 264
 265                   memcpy (hc + 1, &pkt6_udp->udp_hdr,
 266                           ntohs (pkt6_udp->udp_hdr.len));
 267
 268                 }
 269               else if (0x06 == pkt6->ip6_hdr.nxthdr
 270                        && (me->desc.
 271                            service_type & htonl (GNUNET_DNS_SERVICE_TYPE_TCP))
 272                        &&
 273                        (port_in_ports (me->desc.ports, pkt6_tcp->tcp_hdr.dpt)))
 274                 {
 275                   hdr->type = ntohs (GNUNET_MESSAGE_TYPE_SERVICE_TCP);
 276
 277                   memcpy (hc + 1, &pkt6_tcp->tcp_hdr,
 278                           ntohs (pkt6->ip6_hdr.paylgth));
 279
 280                 }
 281               else
 282                 {
 283                   GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Dropping packet. nxthdr=%d, type=%d, dpt=%x, flg=%d, ports=%x\n",
 284                              pkt6->ip6_hdr.nxthdr, ntohl(me->desc.service_type),
 285                              ntohs(pkt6_tcp->tcp_hdr.dpt), pkt6_tcp->tcp_hdr.flg, me->desc.ports);
 286                   GNUNET_free (cls);
 287                   cls = NULL;
 288                 }
 289               if (me->tunnel == NULL && NULL != cls)
 290                 {
 291                   *cls =
 292                     GNUNET_MESH_peer_request_connect_all (mesh_handle,
 293                                                           GNUNET_TIME_UNIT_FOREVER_REL,
 294                                                           1,
 295                                                           (struct
 296                                                            GNUNET_PeerIdentity
 297                                                            *) &me->desc.peer,
 298                                                           send_pkt_to_peer,
 299                                                           NULL, cls);
 300                   me->tunnel = *cls;
 301                 }
 302               else if (NULL != cls)
 303                 {
 304                   *cls = me->tunnel;
 305                   send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1,
 306                                     NULL);
 307                   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 308                               "Queued to send to peer %x, type %d\n",
 309                               *((unsigned int *) &me->desc.peer), ntohs(hdr->type));
 310                 }
 311             }
 312           break;
 313         case 0x3a:
 314           /* ICMPv6 */
 315           pkt6_icmp = (struct ip6_icmp *) pkt6;
 316           /* If this packet is an icmp-echo-request and a mapping exists, answer */
 317           if (pkt6_icmp->icmp_hdr.type == 0x80
 318               && (key = address_mapping_exists (pkt6->ip6_hdr.dadr)) != NULL)
 319             {
 320               GNUNET_free (key);
 321               pkt6_icmp = GNUNET_malloc (ntohs (pkt6->shdr.size));
 322               memcpy (pkt6_icmp, pkt6, ntohs (pkt6->shdr.size));
 323               GNUNET_SCHEDULER_add_now (&send_icmp_response, pkt6_icmp);
 324             }
 325           break;
 326         }
 327     }
 328   /* ethertype is ipv4 */
 329   else if (ntohs (pkt_tun->tun.type) == 0x0800)
 330     {
 331       struct ip_pkt *pkt = (struct ip_pkt *) message;
 332       struct ip_udp *udp = (struct ip_udp *) message;
 333       GNUNET_assert (pkt->ip_hdr.version == 4);
 334
 335       /* Send dns-packets to the service-dns */
 336       if (pkt->ip_hdr.proto == 0x11 && ntohs (udp->udp_hdr.dpt) == 53)
 337         {
 338           /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 339           size_t len =
 340             sizeof (struct query_packet) + ntohs (udp->udp_hdr.len) - 9;
 341
 342           struct query_packet_list *query =
 343             GNUNET_malloc (len + 2 * sizeof (struct query_packet_list *));
 344           query->pkt.hdr.type = htons (GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 345           query->pkt.hdr.size = htons (len);
 346           query->pkt.orig_to = pkt->ip_hdr.dadr;
 347           query->pkt.orig_from = pkt->ip_hdr.sadr;
 348           query->pkt.src_port = udp->udp_hdr.spt;
 349           memcpy (query->pkt.data, udp->data, ntohs (udp->udp_hdr.len) - 8);
 350
 351           GNUNET_CONTAINER_DLL_insert_after (head, tail, tail, query);
 352
 353           GNUNET_assert (head != NULL);
 354
 355           if (dns_connection != NULL)
 356             GNUNET_CLIENT_notify_transmit_ready (dns_connection,
 357                                                  len,
 358                                                  GNUNET_TIME_UNIT_FOREVER_REL,
 359                                                  GNUNET_YES,
 360                                                  &send_query, NULL);
 361         }
 362     }
 363 }
 364
 365 void write_to_helper(void* buf, size_t len)
 366 {
 367   (void)GNUNET_DISK_file_write(helper_handle->fh_to_helper, buf, len);
 368 }
 369
 370 void schedule_helper_write(struct GNUNET_TIME_Relative time, void* cls)
 371 {
 372   GNUNET_SCHEDULER_add_write_file (time, helper_handle->fh_to_helper, &helper_write, cls);
 373 }