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     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 126 }
 127 /*}}}*/
 128
 129 /**
 130  * Send an dns-answer-packet to the helper
 131  */
 132 void
 133 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 134     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 135       return;
 136
 137     struct answer_packet_list* ans = answer_proc_head;
 138     size_t len = ntohs(ans->pkt.hdr.size);
 139
 140     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 141
 142     GNUNET_assert (20 == sizeof (struct ip_hdr));
 143     GNUNET_assert (8 == sizeof (struct udp_pkt));
 144     size_t data_len = len - sizeof(struct answer_packet) + 1;
 145     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 146     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 147
 148     struct ip_udp_dns* pkt = alloca(pkt_len);
 149     GNUNET_assert(pkt != NULL);
 150     memset(pkt, 0, pkt_len);
 151
 152     /* set the gnunet-header */
 153     pkt->shdr.size = htons(pkt_len);
 154     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 155
 156     /* set the tun-header (no flags and ethertype of IPv4) */
 157     pkt->tun.flags = 0;
 158     pkt->tun.type = htons(0x0800);
 159
 160     /* set the ip-header */
 161     pkt->ip_hdr.version = 4;
 162     pkt->ip_hdr.hdr_lngth = 5;
 163     pkt->ip_hdr.diff_serv = 0;
 164     pkt->ip_hdr.tot_lngth = htons(net_len);
 165     pkt->ip_hdr.ident = 0;
 166     pkt->ip_hdr.flags = 0;
 167     pkt->ip_hdr.frag_off = 0;
 168     pkt->ip_hdr.ttl = 255;
 169     pkt->ip_hdr.proto = 0x11; /* UDP */
 170     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 171     pkt->ip_hdr.sadr = ans->pkt.from;
 172     pkt->ip_hdr.dadr = ans->pkt.to;
 173
 174     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 175
 176     /* set the udp-header */
 177     pkt->udp_dns.udp_hdr.spt = htons(53);
 178     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 179     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 180     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 181
 182     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 183
 184     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 185     GNUNET_free(ans);
 186
 187     /* FIXME */ GNUNET_DISK_file_write(helper_handle->fh_to_helper, pkt, pkt_len);
 188
 189     /* if more packets are available, reschedule */
 190     if (answer_proc_head != NULL)
 191       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 192                                        helper_handle->fh_to_helper,
 193                                        &helper_write,
 194                                        NULL);
 195 }
 196 /**
 197  * Receive packets from the helper-process
 198  */
 199 void
 200 message_token(void *cls,
 201               void *client,
 202               const struct GNUNET_MessageHeader *message) {
 203     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 204
 205     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 206
 207     /* ethertype is ipv6 */
 208     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 209       {
 210         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 211         GNUNET_assert(pkt6->ip6_hdr.version == 6);
 212         struct ip6_tcp *pkt6_tcp;
 213         struct ip6_udp *pkt6_udp;
 214         struct ip6_icmp *pkt6_icmp;
 215         GNUNET_HashCode* key;
 216
 217         switch(pkt6->ip6_hdr.nxthdr)
 218           {
 219           case 0x06:
 220             pkt6_tcp = (struct ip6_tcp*)pkt6;
 221             break;
 222           case 0x11:
 223             pkt6_udp = (struct ip6_udp*)pkt6;
 224             if ((key = address_mapping_exists(pkt6->ip6_hdr.dadr)) != NULL)
 225               {
 226                 struct map_entry* me = GNUNET_CONTAINER_multihashmap_get(hashmap, key);
 227                 GNUNET_assert(me != NULL);
 228                 GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Mapping exists; type: %d; UDP is %d; port: %x/%x!\n", me->desc.service_type, htonl(GNUNET_DNS_SERVICE_TYPE_UDP), pkt6_udp->udp_hdr.dpt, me->desc.ports);
 229                 GNUNET_free(key);
 230                 if (me->desc.service_type & htonl(GNUNET_DNS_SERVICE_TYPE_UDP) &&
 231                     (port_in_ports(me->desc.ports, pkt6_udp->udp_hdr.dpt) ||
 232                      port_in_ports(me->additional_ports, pkt6_udp->udp_hdr.dpt)))
 233                   {
 234                     size_t size = sizeof(struct GNUNET_MESH_Tunnel*) + sizeof(struct GNUNET_MessageHeader) + sizeof(GNUNET_HashCode) + ntohs(pkt6_udp->udp_hdr.len);
 235                     struct GNUNET_MESH_Tunnel **cls = GNUNET_malloc(size);
 236                     struct GNUNET_MessageHeader *hdr = (struct GNUNET_MessageHeader*)(cls+1);
 237                     GNUNET_HashCode* hc = (GNUNET_HashCode*)(hdr + 1);
 238
 239                     memcpy(hc, &me->desc.service_descriptor, sizeof(GNUNET_HashCode));
 240                     memcpy(hc+1, &pkt6_udp->udp_hdr, ntohs(pkt6_udp->udp_hdr.len));
 241
 242                     if (me->tunnel == NULL)
 243                       {
 244                         *cls = GNUNET_MESH_peer_request_connect_all(mesh_handle,
 245                                                                     GNUNET_TIME_UNIT_FOREVER_REL,
 246                                                                     1,
 247                                                                     (struct GNUNET_PeerIdentity*)&me->desc.peer,
 248                                                                     send_udp_to_peer,
 249                                                                     NULL,
 250                                                                     cls);
 251                         me->tunnel = *cls;
 252                       }
 253                     else
 254                       {
 255                         *cls = me->tunnel;
 256                         send_udp_to_peer(cls, (struct GNUNET_PeerIdentity*)1, NULL);
 257                       }
 258                     GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Queued to send to peer %x\n", *((unsigned int*)&me->desc.peer));
 259                   }
 260               }
 261             break;
 262           case 0x3a:
 263             /* ICMPv6 */
 264             pkt6_icmp = (struct ip6_icmp*)pkt6;
 265             /* If this packet is an icmp-echo-request and a mapping exists, answer */
 266             if (pkt6_icmp->icmp_hdr.type == 0x80 && (key = address_mapping_exists(pkt6->ip6_hdr.dadr)) != NULL)
 267               {
 268                 GNUNET_free(key);
 269                 pkt6_icmp = GNUNET_malloc(ntohs(pkt6->shdr.size));
 270                 memcpy(pkt6_icmp, pkt6, ntohs(pkt6->shdr.size));
 271                 GNUNET_SCHEDULER_add_now(&send_icmp_response, pkt6_icmp);
 272               }
 273             break;
 274           }
 275       }
 276     /* ethertype is ipv4 */
 277     else if (ntohs(pkt_tun->tun.type) == 0x0800)
 278       {
 279         struct ip_pkt *pkt = (struct ip_pkt*) message;
 280         struct ip_udp *udp = (struct ip_udp*) message;
 281         GNUNET_assert(pkt->ip_hdr.version == 4);
 282
 283         /* Send dns-packets to the service-dns */
 284         if (pkt->ip_hdr.proto == 0x11 && ntohs(udp->udp_hdr.dpt) == 53 )
 285           {
 286             /* 9 = 8 for the udp-header + 1 for the unsigned char data[1]; */
 287             size_t len = sizeof(struct query_packet) + ntohs(udp->udp_hdr.len) - 9;
 288
 289             struct query_packet_list* query = GNUNET_malloc(len + 2*sizeof(struct query_packet_list*));
 290             query->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS);
 291             query->pkt.hdr.size = htons(len);
 292             query->pkt.orig_to = pkt->ip_hdr.dadr;
 293             query->pkt.orig_from = pkt->ip_hdr.sadr;
 294             query->pkt.src_port = udp->udp_hdr.spt;
 295             memcpy(query->pkt.data, udp->data, ntohs(udp->udp_hdr.len) - 8);
 296
 297             GNUNET_CONTAINER_DLL_insert_after(head, tail, tail, query);
 298
 299             GNUNET_assert(head != NULL);
 300
 301             if (dns_connection != NULL)
 302               GNUNET_CLIENT_notify_transmit_ready(dns_connection,
 303                                                   len,
 304                                                   GNUNET_TIME_UNIT_FOREVER_REL,
 305                                                   GNUNET_YES,
 306                                                   &send_query,
 307                                                   NULL);
 308           }
 309       }
 310 }
 311
 312 void write_to_helper(void* buf, size_t len)
 313 {
 314   (void)GNUNET_DISK_file_write(helper_handle->fh_to_helper, buf, len);
 315 }
 316
 317 void schedule_helper_write(struct GNUNET_TIME_Relative time, void* cls)
 318 {
 319   GNUNET_SCHEDULER_add_write_file (time, helper_handle->fh_to_helper, &helper_write, cls);
 320 }