VPP-1283: IPv4 PMTU missing MTU value in ICMP4 message.

[vpp.git] / src / vnet / ip / ip4_forward.c

diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index ce2d619..40fe9dc 100644 (file)
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -1963,6 +1963,29 @@ typedef enum
 #define IP4_MCAST_ADDR_MASK 0xffff7f00
 #endif
 
+always_inline void
+ip4_mtu_check (vlib_buffer_t * b, u16 packet_len,
+              u16 adj_packet_bytes, bool df, u32 * next, u32 * error)
+{
+  if (packet_len > adj_packet_bytes)
+    {
+      *error = IP4_ERROR_MTU_EXCEEDED;
+      if (df)
+       {
+         icmp4_error_set_vnet_buffer
+           (b, ICMP4_destination_unreachable,
+            ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
+            adj_packet_bytes);
+         *next = IP4_REWRITE_NEXT_ICMP_ERROR;
+       }
+      else
+       {
+         /* Add support for fragmentation here */
+         *next = IP4_REWRITE_NEXT_DROP;
+       }
+    }
+}
+
 always_inline uword
 ip4_rewrite_inline (vlib_main_t * vm,
                    vlib_node_runtime_t * node,
@@ -2123,26 +2146,16 @@ ip4_rewrite_inline (vlib_main_t * vm,
          vnet_buffer (p1)->ip.save_rewrite_length = rw_len1;
 
          /* Check MTU of outgoing interface. */
-         if (vlib_buffer_length_in_chain (vm, p0) >
-             adj0[0].rewrite_header.max_l3_packet_bytes)
-           {
-             error0 = IP4_ERROR_MTU_EXCEEDED;
-             next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
-             icmp4_error_set_vnet_buffer
-               (p0, ICMP4_destination_unreachable,
-                ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
-                0);
-           }
-         if (vlib_buffer_length_in_chain (vm, p1) >
-             adj1[0].rewrite_header.max_l3_packet_bytes)
-           {
-             error1 = IP4_ERROR_MTU_EXCEEDED;
-             next1 = IP4_REWRITE_NEXT_ICMP_ERROR;
-             icmp4_error_set_vnet_buffer
-               (p1, ICMP4_destination_unreachable,
-                ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
-                0);
-           }
+         ip4_mtu_check (p0, clib_net_to_host_u16 (ip0->length),
+                        adj0[0].rewrite_header.max_l3_packet_bytes,
+                        ip0->flags_and_fragment_offset &
+                        clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
+                        &next0, &error0);
+         ip4_mtu_check (p1, clib_net_to_host_u16 (ip1->length),
+                        adj1[0].rewrite_header.max_l3_packet_bytes,
+                        ip1->flags_and_fragment_offset &
+                        clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
+                        &next1, &error1);
 
          if (is_mcast)
            {
@@ -2326,16 +2339,12 @@ ip4_rewrite_inline (vlib_main_t * vm,
               vlib_buffer_length_in_chain (vm, p0) + rw_len0);
 
          /* Check MTU of outgoing interface. */
-         if (vlib_buffer_length_in_chain (vm, p0) >
-             adj0[0].rewrite_header.max_l3_packet_bytes)
-           {
-             error0 = IP4_ERROR_MTU_EXCEEDED;
-             next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
-             icmp4_error_set_vnet_buffer
-               (p0, ICMP4_destination_unreachable,
-                ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
-                0);
-           }
+         ip4_mtu_check (p0, clib_net_to_host_u16 (ip0->length),
+                        adj0[0].rewrite_header.max_l3_packet_bytes,
+                        ip0->flags_and_fragment_offset &
+                        clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
+                        &next0, &error0);
+
          if (is_mcast)
            {
              error0 = ((adj0[0].rewrite_header.sw_if_index ==