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_core_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
  36 #include "gnunet-daemon-vpn-dns.h"
  37 #include "gnunet-daemon-vpn.h"
  38 #include "gnunet-daemon-vpn-helper.h"
  39 #include "gnunet-service-dns-p.h"
  40 #include "gnunet-vpn-packet.h"
  41
  42 /**
  43  * PipeHandle to receive data from the helper
  44  */
  45 static struct GNUNET_DISK_PipeHandle* helper_in;
  46
  47 /**
  48  * PipeHandle to send data to the helper
  49  */
  50 static struct GNUNET_DISK_PipeHandle* helper_out;
  51
  52 /**
  53  * FileHandle to receive data from the helper
  54  */
  55 static const struct GNUNET_DISK_FileHandle* fh_from_helper;
  56
  57 /**
  58  * FileHandle to send data to the helper
  59  */
  60 static const struct GNUNET_DISK_FileHandle* fh_to_helper;
  61
  62 /**
  63  * Start the helper-process
  64  * {{{
  65  */
  66 void
  67 start_helper_and_schedule(void *cls,
  68                           const struct GNUNET_SCHEDULER_TaskContext *tc) {
  69     if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
  70       return;
  71
  72     helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO);
  73     helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_NO, GNUNET_YES);
  74
  75     if (helper_in == NULL || helper_out == NULL) return;
  76
  77     helper_proc = GNUNET_OS_start_process(helper_in, helper_out, "gnunet-helper-vpn", "gnunet-helper-vpn", NULL);
  78
  79     fh_from_helper = GNUNET_DISK_pipe_handle (helper_out, GNUNET_DISK_PIPE_END_READ);
  80     fh_to_helper = GNUNET_DISK_pipe_handle (helper_in, GNUNET_DISK_PIPE_END_WRITE);
  81
  82     GNUNET_DISK_pipe_close_end(helper_out, GNUNET_DISK_PIPE_END_WRITE);
  83     GNUNET_DISK_pipe_close_end(helper_in, GNUNET_DISK_PIPE_END_READ);
  84
  85     /* Tell the dns-service to rehijack the dns-port
  86      * The routing-table gets flushed if an interface disappears.
  87      */
  88     restart_hijack = 1;
  89     GNUNET_CLIENT_notify_transmit_ready(dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
  90
  91     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
  92 }
  93 /*}}}*/
  94 /**
  95  * Restart the helper-process
  96  * {{{
  97  */
  98 void
  99 restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
 100     // Kill the helper
 101     GNUNET_OS_process_kill (helper_proc, SIGKILL);
 102     GNUNET_OS_process_wait (helper_proc);
 103     GNUNET_OS_process_close (helper_proc);
 104     helper_proc = NULL;
 105
 106     GNUNET_DISK_pipe_close(helper_in);
 107     GNUNET_DISK_pipe_close(helper_out);
 108
 109     /* Restart the helper */
 110     GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS, start_helper_and_schedule, NULL);
 111 }
 112 /*}}}*/
 113
 114 /**
 115  * Read from the helper-process
 116  * {{{
 117  */
 118 void
 119 helper_read(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 120     /* no message can be bigger then 64k */
 121     char buf[65535];
 122
 123     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 124       return;
 125
 126     int t = GNUNET_DISK_file_read(fh_from_helper, &buf, 65535);
 127
 128     /* On read-error, restart the helper */
 129     if (t<=0) {
 130         GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Read error for header from vpn-helper: %m\n");
 131         GNUNET_SCHEDULER_add_now(restart_helper, cls);
 132         return;
 133     }
 134
 135     /* FIXME */ GNUNET_SERVER_mst_receive(mst, NULL, buf, t, 0, 0);
 136
 137     GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, fh_from_helper, &helper_read, NULL);
 138 }
 139 /*}}}*/
 140
 141 /**
 142  * Send an dns-answer-packet to the helper
 143  */
 144 void
 145 helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tsdkctx) {
 146     if (tsdkctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
 147       return;
 148
 149     struct answer_packet_list* ans = answer_proc_head;
 150     size_t len = ntohs(ans->pkt.hdr.size);
 151
 152     GNUNET_assert(ans->pkt.subtype == GNUNET_DNS_ANSWER_TYPE_IP);
 153
 154     GNUNET_assert (20 == sizeof (struct ip_hdr));
 155     GNUNET_assert (8 == sizeof (struct udp_pkt));
 156     size_t data_len = len - sizeof(struct answer_packet) + 1;
 157     size_t net_len = sizeof(struct ip_hdr) + sizeof(struct udp_dns) + data_len;
 158     size_t pkt_len = sizeof(struct GNUNET_MessageHeader) + sizeof(struct pkt_tun) + net_len;
 159
 160     struct ip_udp_dns* pkt = alloca(pkt_len);
 161     GNUNET_assert(pkt != NULL);
 162     memset(pkt, 0, pkt_len);
 163
 164     /* set the gnunet-header */
 165     pkt->shdr.size = htons(pkt_len);
 166     pkt->shdr.type = htons(GNUNET_MESSAGE_TYPE_VPN_HELPER);
 167
 168     /* set the tun-header (no flags and ethertype of IPv4) */
 169     pkt->tun.flags = 0;
 170     pkt->tun.type = htons(0x0800);
 171
 172     /* set the ip-header */
 173     pkt->ip_hdr.version = 4;
 174     pkt->ip_hdr.hdr_lngth = 5;
 175     pkt->ip_hdr.diff_serv = 0;
 176     pkt->ip_hdr.tot_lngth = htons(net_len);
 177     pkt->ip_hdr.ident = 0;
 178     pkt->ip_hdr.flags = 0;
 179     pkt->ip_hdr.frag_off = 0;
 180     pkt->ip_hdr.ttl = 255;
 181     pkt->ip_hdr.proto = 0x11; /* UDP */
 182     pkt->ip_hdr.chks = 0; /* Will be calculated later*/
 183     pkt->ip_hdr.sadr = ans->pkt.from;
 184     pkt->ip_hdr.dadr = ans->pkt.to;
 185
 186     pkt->ip_hdr.chks = calculate_ip_checksum((uint16_t*)&pkt->ip_hdr, 5*4);
 187
 188     /* set the udp-header */
 189     pkt->udp_dns.udp_hdr.spt = htons(53);
 190     pkt->udp_dns.udp_hdr.dpt = ans->pkt.dst_port;
 191     pkt->udp_dns.udp_hdr.len = htons(net_len - sizeof(struct ip_hdr));
 192     pkt->udp_dns.udp_hdr.crc = 0; /* Optional for IPv4 */
 193
 194     memcpy(&pkt->udp_dns.data, ans->pkt.data, data_len);
 195
 196     GNUNET_CONTAINER_DLL_remove (answer_proc_head, answer_proc_tail, ans);
 197     GNUNET_free(ans);
 198
 199     /* FIXME */ GNUNET_DISK_file_write(fh_to_helper, pkt, pkt_len);
 200
 201     /* if more packets are available, reschedule */
 202     if (answer_proc_head != NULL)
 203       GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
 204                                        fh_to_helper,
 205                                        &helper_write,
 206                                        NULL);
 207 }
 208 /**
 209  * Receive packets from the helper-process
 210  */
 211 void
 212 message_token(void *cls,
 213               void *client,
 214               const struct GNUNET_MessageHeader *message) {
 215     GNUNET_assert(ntohs(message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
 216
 217     struct tun_pkt *pkt_tun = (struct tun_pkt*) message;
 218
 219     /* ethertype is ipv6 */
 220     if (ntohs(pkt_tun->tun.type) == 0x86dd)
 221       {
 222         struct ip6_pkt *pkt6 = (struct ip6_pkt*) message;
 223         GNUNET_assert(pkt6->ip6_hdr.version == 6);
 224         struct ip6_tcp *pkt6_tcp;
 225         struct ip6_udp *pkt6_udp;
 226         struct ip6_icmp *pkt6_icmp;
 227         GNUNET_HashCode* key;
 228
 229         switch(pkt6->ip6_hdr.nxthdr)
 230           {
 231           case 0x06:
 232             pkt6_tcp = (struct ip6_tcp*)pkt6;
 233             break;
 234           case 0x11:
 235             pkt6_udp = (struct ip6_udp*)pkt6;
 236             if ((key = address_mapping_exists(pkt6->ip6_hdr.dadr)) != NULL)
 237               {
 238                 struct map_entry* me = GNUNET_CONTAINER_multihashmap_get(hashmap, key);
 239                 GNUNET_assert(me != NULL);
 240                 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);
 241                 GNUNET_free(key);
 242                 if (me->desc.service_type & htonl(GNUNET_DNS_SERVICE_TYPE_UDP) &&
 243                     (port_in_ports(me->desc.ports, pkt6_udp->udp_hdr.dpt) ||
 244                      port_in_ports(me->additional_ports, pkt6_udp->udp_hdr.dpt)))
 245                   {
 246                     size_t size = sizeof(struct GNUNET_PeerIdentity) + sizeof(struct GNUNET_MessageHeader) + sizeof(GNUNET_HashCode) + ntohs(pkt6_udp->udp_hdr.len);
 247                     struct GNUNET_PeerIdentity *cls = GNUNET_malloc(size);
 248                     struct GNUNET_MessageHeader *hdr = (struct GNUNET_MessageHeader*)(cls+1);
 249                     GNUNET_HashCode* hc = (GNUNET_HashCode*)(hdr + 1);
 250                     memcpy(cls, &me->desc.peer, sizeof(struct GNUNET_PeerIdentity));
 251                     memcpy(hc, &me->desc.service_descriptor, sizeof(GNUNET_HashCode));
 252                     memcpy(hc+1, &pkt6_udp->udp_hdr, ntohs(pkt6_udp->udp_hdr.len));
 253                     GNUNET_CORE_peer_request_connect(core_handle,
 254                                         GNUNET_TIME_UNIT_FOREVER_REL,
 255                                         (struct GNUNET_PeerIdentity*)&me->desc.peer,
 256                                         send_udp_to_peer,
 257                                         cls);
 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(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, fh_to_helper, &helper_write, cls);
 320 }