npt66: icmp6 alg to handle icmp6 error messages

Support rewriting the inner packet for ICMP6 error messages.

Type: feature
Change-Id: I7e11f53626037075a23310f1cb7e673b0cb52843
Signed-off-by: Ole Troan <otroan@employees.org>

1 files changed, 76 insertions, 1 deletions

diff --git a/src/plugins/npt66/npt66_node.c b/src/plugins/npt66/npt66_node.c
index ebe33593700..f74f9143998 100644
--- a/src/plugins/npt66/npt66_node.c
+++ b/src/plugins/npt66/npt66_node.c
@@ -159,6 +159,69 @@ done:
   return rv;
 }
 
+static int
+npt66_icmp6_translate (vlib_buffer_t *b, ip6_header_t *outer_ip,
+		       icmp46_header_t *icmp, npt66_binding_t *binding,
+		       int dir)
+{
+  ip6_header_t *ip = (ip6_header_t *) (icmp + 2);
+  int rv = 0;
+  vlib_main_t *vm = vlib_get_main ();
+
+  if (clib_net_to_host_u16 (outer_ip->payload_length) <
+      sizeof (icmp46_header_t) + 4 + sizeof (ip6_header_t))
+    {
+      clib_warning ("ICMP6 payload too short");
+      return -1;
+    }
+
+  // Validate checksums
+  int bogus_length;
+  u16 sum16;
+  sum16 = ip6_tcp_udp_icmp_compute_checksum (vm, b, outer_ip, &bogus_length);
+  if (sum16 != 0 && sum16 != 0xffff)
+    {
+      clib_warning ("ICMP6 checksum failed");
+      return -1;
+    }
+  if (dir == VLIB_RX)
+    {
+      if (!ip6_prefix_cmp (ip->src_address, binding->external,
+			   binding->external_plen))
+	{
+	  clib_warning (
+	    "npt66_icmp6_translate: src address is not internal (%U -> %U)",
+	    format_ip6_address, &ip->src_address, format_ip6_address,
+	    &ip->dst_address);
+	  goto done;
+	}
+      ip->src_address = ip6_prefix_copy (ip->src_address, binding->internal,
+					 binding->internal_plen);
+      /* Checksum neutrality */
+      rv = npt66_adjust_checksum (binding->internal_plen, true, binding->delta,
+				  &ip->src_address);
+    }
+  else
+    {
+      if (!ip6_prefix_cmp (ip->dst_address, binding->external,
+			   binding->external_plen))
+	{
+	  clib_warning (
+	    "npt66_icmp6_translate: dst address is not external (%U -> %U)",
+	    format_ip6_address, &ip->src_address, format_ip6_address,
+	    &ip->dst_address);
+	  goto done;
+	}
+      ip->dst_address = ip6_prefix_copy (ip->dst_address, binding->internal,
+					 binding->internal_plen);
+      rv = npt66_adjust_checksum (binding->internal_plen, false,
+				  binding->delta, &ip->dst_address);
+    }
+done:
+
+  return rv;
+}
+
 /*
  * Lookup the packet tuple in the flow cache, given the lookup mask.
  * If a binding is found, rewrite the packet according to instructions,
@@ -194,8 +257,20 @@ npt66_node_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 
       /* By default pass packet to next node in the feature chain */
       vnet_feature_next_u16 (next, b[0]);
+      int rv;
+      icmp46_header_t *icmp = (icmp46_header_t *) (ip + 1);
+      if (ip->protocol == IP_PROTOCOL_ICMP6 && icmp->type < 128)
+	{
+	  rv = npt66_icmp6_translate (b[0], ip, icmp, binding, dir);
+	  if (rv < 0)
+	    {
+	      clib_warning ("ICMP6 npt66_translate failed");
+	      *next = NPT66_NEXT_DROP;
+	      goto next;
+	    }
+	}
+      rv = npt66_translate (ip, binding, dir);
 
-      int rv = npt66_translate (ip, binding, dir);
       if (rv < 0)
 	{
 	  vlib_node_increment_counter (vm, node->node_index,