src/vpn/gnunet-service-dns.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2009 Christian Grothoff (and other contributing authors)
   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-service-dns.c
  23  * @author Philipp Tölke
  24  */
  25 #include "platform.h"
  26 #include "gnunet_getopt_lib.h"
  27 #include "gnunet_service_lib.h"
  28 #include "gnunet_network_lib.h"
  29 #include "gnunet_os_lib.h"
  30 #include "gnunet-service-dns-p.h"
  31 #include "gnunet_protocols.h"
  32 #include "gnunet-vpn-packet.h"
  33 #include "gnunet-vpn-pretty-print.h"
  34
  35 #define WE_DO_THIS_TO_GET_THE_PORT_WE_BOUND_TO_IN_ORDER_TO_HIJACK_EVERYTHING_BUT_THIS_PORT 1
  36 #define WHY_ON_EARTH_DO_WE_DO_THIS WE_DO_THIS_TO_GET_THE_PORT_WE_BOUND_TO_IN_ORDER_TO_HIJACK_EVERYTHING_BUT_THIS_PORT
  37
  38 struct dns_cls {
  39         struct GNUNET_SCHEDULER_Handle *sched;
  40
  41         struct GNUNET_NETWORK_Handle *dnsout;
  42
  43         unsigned short dnsoutport;
  44 };
  45
  46 static struct dns_cls mycls;
  47
  48 void hijack(unsigned short port) {
  49         char port_s[6];
  50
  51         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Hijacking, port is %d\n", port);
  52         snprintf(port_s, 6, "%d", port);
  53         GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", port_s, NULL);
  54 }
  55
  56 void unhijack(unsigned short port) {
  57         char port_s[6];
  58
  59         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "unHijacking, port is %d\n", port);
  60         snprintf(port_s, 6, "%d", port);
  61         GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", "-d", port_s, NULL);
  62 }
  63
  64 void receive_query(void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message)
  65 {
  66         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Received query!\n");
  67         struct query_packet* pkt = (struct query_packet*)message;
  68         GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Of length %d\n", ntohs(pkt->hdr.size));
  69         struct dns_pkt* dns = (struct dns_pkt*)pkt->data;
  70
  71         pkt_printf_dns(dns);
  72
  73         GNUNET_SERVER_receive_done(client, GNUNET_OK);
  74 }
  75
  76 /**
  77  * Task run during shutdown.
  78  *
  79  * @param cls unused
  80  * @param tc unused
  81  */
  82 static void
  83 cleanup_task (void *cls,
  84               const struct GNUNET_SCHEDULER_TaskContext *tc)
  85 {
  86         unhijack(mycls.dnsoutport);
  87 }
  88
  89 /**
  90  * @param cls closure
  91  * @param sched scheduler to use
  92  * @param server the initialized server
  93  * @param cfg configuration to use
  94  */
  95 static void
  96 run (void *cls,
  97      struct GNUNET_SCHEDULER_Handle *sched,
  98      struct GNUNET_SERVER_Handle *server,
  99      const struct GNUNET_CONFIGURATION_Handle *cfg)
 100 {
 101   static const struct GNUNET_SERVER_MessageHandler handlers[] = {
 102           /* callback, cls, type, size */
 103     {&receive_query, NULL, GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS, 0},
 104     {NULL, NULL, 0, 0}
 105   };
 106   struct sockaddr_in addr;
 107
 108   mycls.sched = sched;
 109   mycls.dnsout = GNUNET_NETWORK_socket_create (AF_INET, SOCK_DGRAM, 0);
 110   if (mycls.dnsout == NULL)
 111     return;
 112   memset(&addr, 0, sizeof(struct sockaddr_in));
 113
 114   int err = GNUNET_NETWORK_socket_bind (mycls.dnsout,
 115                                         (struct sockaddr*)&addr,
 116                                         sizeof(struct sockaddr_in));
 117
 118   if (err != GNUNET_YES) {
 119         GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not bind a port, exiting\n");
 120         return;
 121   }
 122 #if WHY_ON_EARTH_DO_WE_DO_THIS
 123   socklen_t addrlen = sizeof(struct sockaddr_in);
 124   err = getsockname(GNUNET_NETWORK_get_fd(mycls.dnsout),
 125                     (struct sockaddr*) &addr,
 126                     &addrlen);
 127 #endif
 128
 129   mycls.dnsoutport = htons(addr.sin_port);
 130
 131   hijack(htons(addr.sin_port));
 132
 133   GNUNET_SERVER_add_handlers (server, handlers);
 134   GNUNET_SCHEDULER_add_delayed (sched,
 135                   GNUNET_TIME_UNIT_FOREVER_REL,
 136                   &cleanup_task,
 137                   cls);
 138 }
 139
 140 /**
 141  * The main function for the dns service.
 142  *
 143  * @param argc number of arguments from the command line
 144  * @param argv command line arguments
 145  * @return 0 ok, 1 on error
 146  */
 147 int
 148 main (int argc, char *const *argv)
 149 {
 150   return (GNUNET_OK ==
 151           GNUNET_SERVICE_run (argc,
 152                               argv,
 153                               "gnunet-service-dns",
 154                               GNUNET_SERVICE_OPTION_NONE,
 155                               &run, NULL)) ? 0 : 1;
 156 }