[GNUnet-SVN] r19039 - gnunet/src/exit

[gnunet]

Author: grothoff
Date: 2012-01-06 23:25:49 +0100 (Fri, 06 Jan 2012)
New Revision: 19039

Modified:
   gnunet/src/exit/gnunet-daemon-exit.c
   gnunet/src/exit/gnunet-helper-exit.c
Log:
-finshing first round of re-implementation; missing structs should be done 
together with entry-component

Modified: gnunet/src/exit/gnunet-daemon-exit.c
===================================================================
--- gnunet/src/exit/gnunet-daemon-exit.c        2012-01-06 21:46:57 UTC (rev 
19038)
+++ gnunet/src/exit/gnunet-daemon-exit.c        2012-01-06 22:25:49 UTC (rev 
19039)
@@ -25,7 +25,6 @@
  * @author Christian Grothoff
  *
  * TODO:
- * - setup_fresh_address is not implemented
  * - need proper message headers for mesh P2P messages
  * - factor out crc computations from DNS/EXIT into shared library?
  */
@@ -891,42 +890,87 @@
  */
 static void
 setup_fresh_address (int af,
-                    int proto,
+                    uint8_t proto,
                     struct SocketAddress *local_address)
 {
+  local_address->af = af;
+  local_address->proto = (uint8_t) proto;
+  /* default "local" port range is often 32768--61000,
+     so we pick a random value in that range */         
+  local_address->port 
+    = (uint16_t) 32768 + GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 
+                                                  28232);      
   switch (af)
   {
   case AF_INET:
     {
       const char *ipv4addr = exit_argv[4];
       const char *ipv4mask = exit_argv[5];
-      uint32_t tmp;
-      uint32_t tmp2;
-      
-      GNUNET_assert (1 == inet_pton (AF_INET, ipv4addr, &tmp));
-      GNUNET_assert (1 == inet_pton (AF_INET, ipv4mask, &tmp2));
-      // FIXME
-      /* This should be a noop */
-      tmp = tmp & tmp2;
-      tmp |= ntohl (*((uint32_t *) /*tunnel*/ 42)) & (~tmp2);
-      
-      // pkt4->source_address.s_addr = tmp;
+      struct in_addr addr;
+      struct in_addr mask;
+      struct in_addr rnd;
+
+      GNUNET_assert (1 == inet_pton (AF_INET, ipv4addr, &addr));
+      GNUNET_assert (1 == inet_pton (AF_INET, ipv4mask, &mask));           
+      if (0 == ~mask.s_addr)
+      {
+       /* only one valid IP anyway */
+       local_address->address.ipv4 = addr;
+       return;
+      }
+      /* Given 192.168.0.1/255.255.0.0, we want a mask 
+        of '192.168.255.255', thus:  */
+      mask.s_addr = addr.s_addr | ~mask.s_addr;
+      /* Pick random IPv4 address within the subnet, except 'addr' or 'mask' 
itself */
+      do
+       {
+         rnd.s_addr = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 
+                                                UINT32_MAX);   
+         local_address->address.ipv4.s_addr = (addr.s_addr | rnd.s_addr) & 
mask.s_addr;
+       }
+      while ( (local_address->address.ipv4.s_addr == addr.s_addr) ||
+             (local_address->address.ipv4.s_addr == mask.s_addr) );
     }
     break;
   case AF_INET6:
     {
       const char *ipv6addr = exit_argv[2];
-      /* Generate a new src-address
-       * This takes as much from the address of the tunnel as fits into
-       * the host-mask*/
-      unsigned long long ipv6prefix_r = (ipv6prefix + 7) / 8;
-      inet_pton (AF_INET6, ipv6addr, &local_address->address.ipv6);
-      if (ipv6prefix_r < (16 - sizeof (void *)))
-       ipv6prefix_r = 16 - sizeof (void *);
+      struct in6_addr addr;
+      struct in6_addr mask;
+      struct in6_addr rnd;
+      int i;
+
+      GNUNET_assert (1 == inet_pton (AF_INET6, ipv6addr, &addr));
+      GNUNET_assert (ipv6prefix < 128);
+      if (ipv6prefix == 127)
+      {
+       /* only one valid IP anyway */
+       local_address->address.ipv6 = addr;
+       return;
+      }
+      /* Given ABCD::/96, we want a mask of 'ABCD::FFFF:FFFF,
+        thus: */
+      mask = addr;
+      for (i=127;i>=128-ipv6prefix;i--)
+       mask.s6_addr[i / 8] |= (1 << (i % 8));
       
-      unsigned int offset = ipv6prefix_r - (16 - sizeof (void *));
-      // memcpy ((((char *) &pkt6->source_address)) + ipv6prefix_r, ((char *) 
&tunnel) + offset, 16 - ipv6prefix_r);
-      offset++;
+      /* Pick random IPv6 address within the subnet, except 'addr' or 'mask' 
itself */
+      do
+       {
+         for (i=0;i<16;i++)
+         {
+           rnd.s6_addr[i] = (unsigned char) GNUNET_CRYPTO_random_u32 
(GNUNET_CRYPTO_QUALITY_WEAK, 
+                                                                      256);
+           local_address->address.ipv6.s6_addr[i]
+             = (addr.s6_addr[i] | rnd.s6_addr[i]) & mask.s6_addr[i];
+         }
+       }
+      while ( (0 == memcmp (&local_address->address.ipv6,
+                           &addr,
+                           sizeof (struct in6_addr))) ||
+             (0 == memcmp (&local_address->address.ipv6,
+                           &mask,
+                           sizeof (struct in6_addr))) );
     }
     break;
   default:
@@ -1052,7 +1096,7 @@
   pkt4->diff_serv = 0;
   pkt4->total_length = htons ((uint16_t) (sizeof (struct ip4_header) + len));
   pkt4->identification = (uint16_t) GNUNET_CRYPTO_random_u32 
(GNUNET_CRYPTO_QUALITY_WEAK, 
-                                                             65536);
+                                                             UINT16_MAX + 1);
   pkt4->flags = 0;
   pkt4->fragmentation_offset = 0;
   pkt4->ttl = 255;

Modified: gnunet/src/exit/gnunet-helper-exit.c
===================================================================
--- gnunet/src/exit/gnunet-helper-exit.c        2012-01-06 21:46:57 UTC (rev 
19038)
+++ gnunet/src/exit/gnunet-helper-exit.c        2012-01-06 22:25:49 UTC (rev 
19039)
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     (C) 2010 Christian Grothoff
+     (C) 2010, 2011, 2012 Christian Grothoff
 
      GNUnet is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
@@ -19,12 +19,17 @@
 */
 
 /**
- * @file vpn/gnunet-daemon-vpn.c
- * @brief the helper for various vpn-daemons. Opens a virtual 
network-interface,
+ * @file exit/gnunet-helper-exit.c
+ * @brief the helper for exit nodes. Opens a virtual network-interface,
  * sends data received on the if to stdout, sends data received on stdin to the
  * interface
  * @author Philipp Tölke
  *
+ * TODO:
+ * - need to add code to setup ip_forwarding and NAT (for IPv4) so that
+ *   users don't need to ALSO do admin work; this is what will set
+ *   gnunet-helper-exit.c apart from gnunet-helper-vpn.c
+ *
  * The following list of people have reviewed this code and considered
  * it safe since the last modification (if you reviewed it, please
  * have your name added to the list):