X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvnet%2Ftcp%2Ftcp_pg.c;h=07bdb113fd0dfa44fb4d9d7310e447f2e8e0b756;hb=c5df8c71c;hp=3be4592c6799b1878795379b0363994d15c6eaaf;hpb=636815199a1f359fdd0da706985a74eca95254da;p=vpp.git

diff --git a/src/vnet/tcp/tcp_pg.c b/src/vnet/tcp/tcp_pg.c
index 3be4592c679..07bdb113fd0 100644
--- a/src/vnet/tcp/tcp_pg.c
+++ b/src/vnet/tcp/tcp_pg.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Copyright (c) 2016-2019 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
@@ -77,7 +77,11 @@ tcp_pg_edit_function (pg_main_t * pg,
       ASSERT (p0->current_data == 0);
       ip0 = (void *) (p0->data + ip_offset);
       tcp0 = (void *) (p0->data + tcp_offset);
-      tcp_len0 = clib_net_to_host_u16 (ip0->length) - sizeof (ip0[0]);
+      /* if IP length has been specified, then calculate the length based on buffer */
+      if (ip0->length == 0)
+	tcp_len0 = vlib_buffer_length_in_chain (vm, p0) - tcp_offset;
+      else
+	tcp_len0 = clib_net_to_host_u16 (ip0->length) - tcp_offset;
 
       /* Initialize checksum with header. */
       if (BITS (sum0) == 32)