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