ip: fix udp/tcp checksum corner cases

[vpp.git] / src / vnet / ip / ip6_forward.c

diff --git a/src/vnet/ip/ip6_forward.c b/src/vnet/ip/ip6_forward.c
index 252bdf9..067db77 100644 (file)
--- a/src/vnet/ip/ip6_forward.c
+++ b/src/vnet/ip/ip6_forward.c
@@ -1017,7 +1017,8 @@ ip6_tcp_udp_icmp_compute_checksum (vlib_main_t * vm, vlib_buffer_t * p0,
   u16 sum16, payload_length_host_byte_order;
   u32 i, n_this_buffer, n_bytes_left;
   u32 headers_size = sizeof (ip0[0]);
-  void *data_this_buffer;
+  u8 *data_this_buffer;
+  u8 length_odd;
 
   ASSERT (bogus_lengthp);
   *bogus_lengthp = 0;
@@ -1025,7 +1026,7 @@ ip6_tcp_udp_icmp_compute_checksum (vlib_main_t * vm, vlib_buffer_t * p0,
   /* Initialize checksum with ip header. */
   sum0 = ip0->payload_length + clib_host_to_net_u16 (ip0->protocol);
   payload_length_host_byte_order = clib_net_to_host_u16 (ip0->payload_length);
-  data_this_buffer = (void *) (ip0 + 1);
+  data_this_buffer = (u8 *) (ip0 + 1);
 
   for (i = 0; i < ARRAY_LEN (ip0->src_address.as_uword); i++)
     {
@@ -1078,14 +1079,27 @@ ip6_tcp_udp_icmp_compute_checksum (vlib_main_t * vm, vlib_buffer_t * p0,
       if (n_bytes_left == 0)
        break;
 
+      ASSERT (p0->flags & VLIB_BUFFER_NEXT_PRESENT);
       if (!(p0->flags & VLIB_BUFFER_NEXT_PRESENT))
        {
          *bogus_lengthp = 1;
          return 0xfefe;
        }
+
+      length_odd = (n_this_buffer & 1);
+
       p0 = vlib_get_buffer (vm, p0->next_buffer);
       data_this_buffer = vlib_buffer_get_current (p0);
       n_this_buffer = clib_min (p0->current_length, n_bytes_left);
+
+      if (PREDICT_FALSE (length_odd))
+       {
+         /* Prepend a 0 or the resulting checksum will be incorrect. */
+         data_this_buffer--;
+         n_this_buffer++;
+         n_bytes_left++;
+         data_this_buffer[0] = 0;
+       }
     }
 
   sum16 = ~ip_csum_fold (sum0);