Different way of detecting neighbor solicitation requests.

[tinc] / src / route.c

diff --git a/src/route.c b/src/route.c
index bd4341d..00b5298 100644 (file)
--- a/src/route.c
+++ b/src/route.c
@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: route.c,v 1.1.2.31 2002/03/11 13:56:00 guus Exp $
+    $Id: route.c,v 1.1.2.35 2002/03/15 15:40:40 guus Exp $
 */
 
 #include "config.h"
@@ -52,15 +52,15 @@
 
 #include "system.h"
 
+#ifndef s6_addr16
+#define s6_addr16 __u6_addr.__u6_addr16
+#endif
+
 int routing_mode = RMODE_ROUTER;
 int priorityinheritance = 0;
 int macexpire = 600;
 subnet_t mymac;
 
-#ifdef HAVE_FREEBSD
-#define s6_addr16 __u6_addr.__u6_addr16
-#endif
-
 void learn_mac(mac_t *address)
 {
   subnet_t *subnet;
@@ -190,14 +190,38 @@ cp
   return subnet->owner;  
 }
 
-node_t *route_neighborsol(vpn_packet_t *packet)
+unsigned short int inet_checksum(unsigned short int *data, int len, unsigned short int prevsum)
+{
+  unsigned long int checksum = prevsum ^ 0xFFFF;
+
+  while(len--)
+    checksum += ntohs(*data++);
+
+  while(checksum >> 16)
+    checksum = (checksum & 0xFFFF) + (checksum >> 16);
+
+  return checksum ^ 0xFFFF;
+}
+
+void route_neighborsol(vpn_packet_t *packet)
 {
   struct ip6_hdr *hdr;
   struct nd_neighbor_solicit *ns;
+  struct nd_opt_hdr *opt;
   subnet_t *subnet;
+  short unsigned int checksum;
+  
+  struct {
+    struct in6_addr ip6_src;      /* source address */
+    struct in6_addr ip6_dst;      /* destination address */
+    uint32_t length;
+    uint8_t junk[4];
+  } pseudo;
+
 cp
   hdr = (struct ip6_hdr *)(packet->data + 14);
-  ns = (struct nd_neighbor_solicit *)(packet->data + 14 + sizeof(struct ip6_hdr));
+  ns = (struct nd_neighbor_solicit *)(packet->data + 14 + sizeof(*hdr));
+  opt = (struct nd_opt_hdr *)(packet->data + 14 + sizeof(*hdr) + sizeof(*ns));
 
   /* First, snatch the source address from the neighbor solicitation packet */
 
@@ -205,7 +229,8 @@ cp
 
   /* Check if this is a valid neighbor solicitation request */
   
-  if(ns->nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT)
+  if(ns->nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
+     opt->nd_opt_type != ND_OPT_SOURCE_LINKADDR)
     {
       if(debug_lvl > DEBUG_TRAFFIC)
         {
@@ -214,6 +239,26 @@ cp
       return;
     }
 
+  /* Create pseudo header */
+
+  memcpy(&pseudo.ip6_src, &hdr->ip6_src, 16);
+  memcpy(&pseudo.ip6_dst, &hdr->ip6_dst, 16);
+  pseudo.length = htonl(sizeof(*ns) + sizeof(*opt) + 6);
+  pseudo.junk[0] = pseudo.junk[1] = pseudo.junk[2] = 0;
+  pseudo.junk[3] = IPPROTO_ICMPV6;
+  
+  /* Generate checksum */
+  
+  checksum = inet_checksum((unsigned short int *)&pseudo, sizeof(pseudo)/2, ~0);
+  checksum = inet_checksum((unsigned short int *)ns, sizeof(*ns)/2 + 4, checksum);
+
+  if(checksum)
+    {
+      if(debug_lvl >= DEBUG_TRAFFIC)
+          syslog(LOG_WARNING, _("Cannot route packet: checksum error for neighbor solicitation request"));
+      return;
+    }
+
   /* Check if the IPv6 address exists on the VPN */
 
   subnet = lookup_subnet_ipv6((ipv6_t *)&ns->nd_ns_target);
@@ -227,17 +272,46 @@ cp
                  ntohs(ns->nd_ns_target.s6_addr16[4]), ntohs(ns->nd_ns_target.s6_addr16[5]), ntohs(ns->nd_ns_target.s6_addr16[6]), ntohs(ns->nd_ns_target.s6_addr16[7]));
         }
 
-      return NULL;
+      return;
     }
 
   /* Check if it is for our own subnet */
   
   if(subnet->owner == myself)
-    return NULL;       /* silently ignore */
+    return;    /* silently ignore */
+
+  /* Create neighbor advertation reply */
+
+  memcpy(packet->data, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN); /* copy destination address */
+  packet->data[ETHER_ADDR_LEN*2 - 1] ^= 0xFF;                          /* mangle source address so it looks like it's not from us */
 
-  /* Forward to destination */
+  memcpy(&hdr->ip6_dst, &hdr->ip6_src, 16);                            /* swap destination and source protocol address */
+  memcpy(&hdr->ip6_src, &ns->nd_ns_target, 16);                                /* ... */
 
-  return subnet->owner;
+  memcpy((char *)opt + sizeof(*opt), packet->data + ETHER_ADDR_LEN, 6);        /* add fake source hard addr */
+
+  ns->nd_ns_hdr.icmp6_cksum = 0;
+  ns->nd_ns_hdr.icmp6_type = ND_NEIGHBOR_ADVERT;
+  ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[0] = 0x40;                 /* Set solicited flag */
+  ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[1] = ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[2] = ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[3] = 0;
+  opt->nd_opt_type = ND_OPT_TARGET_LINKADDR;
+
+  /* Create pseudo header */
+  
+  memcpy(&pseudo.ip6_src, &hdr->ip6_src, 16);
+  memcpy(&pseudo.ip6_dst, &hdr->ip6_dst, 16);
+  pseudo.length = htonl(sizeof(*ns) + sizeof(*opt) + 6);
+  pseudo.junk[0] = pseudo.junk[1] = pseudo.junk[2] = 0;
+  pseudo.junk[3] = IPPROTO_ICMPV6;
+  
+  /* Generate checksum */
+  
+  checksum = inet_checksum((unsigned short int *)&pseudo, sizeof(pseudo)/2, ~0);
+  checksum = inet_checksum((unsigned short int *)ns, sizeof(*ns)/2 + 4, checksum);
+
+  ns->nd_ns_hdr.icmp6_cksum = htons(checksum);
+
+  write_packet(packet);
 cp
 }
 
@@ -325,9 +399,12 @@ cp
               n = route_ipv4(packet);
               break;
             case 0x86DD:
+              if(packet->data[20] == IPPROTO_ICMPV6 && packet->data[54] = ND_NEIGHBOR_SOLICIT)
+               {
+                 route_neighborsol(packet);
+                 return;
+               }
               n = route_ipv6(packet);
-             if(!n && packet->data[0] == 0x33 && packet->data[1] == 0x33 && packet->data[2] == 0xff)
-               n = route_neighborsol(packet);
               break;
             case 0x0806:
               route_arp(packet);