nat: respect udp checksum

Type: fix

Change-Id: I73895fa0101bd50483160c8dc6faac2c67513077
Signed-off-by: Filip Varga <fivarga@cisco.com>
(cherry picked from commit 0d75f783644a24b219ed79d9f9c17387783f67ca)

1 files changed, 74 insertions, 36 deletions

diff --git a/src/plugins/nat/in2out.c b/src/plugins/nat/in2out.c
index c69bc61236b..802202d7939 100755
--- a/src/plugins/nat/in2out.c
+++ b/src/plugins/nat/in2out.c
@@ -1075,12 +1075,11 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
 				 src_address /* changed member */ );
 	  ip0->checksum = ip_csum_fold (sum0);
 
+	  old_port0 = udp0->src_port;
+	  new_port0 = udp0->src_port = s0->out2in.port;
+
 	  if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
 	    {
-	      old_port0 = tcp0->src_port;
-	      tcp0->src_port = s0->out2in.port;
-	      new_port0 = tcp0->src_port;
-
 	      sum0 = tcp0->checksum;
 	      sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 				     ip4_header_t,
@@ -1094,9 +1093,17 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
 	    }
 	  else
 	    {
-	      old_port0 = udp0->src_port;
-	      udp0->src_port = s0->out2in.port;
-	      udp0->checksum = 0;
+	      if (PREDICT_FALSE (udp0->checksum))
+		{
+		  sum0 = udp0->checksum;
+		  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+					 ip4_header_t,
+					 dst_address /* changed member */ );
+		  sum0 = ip_csum_update (sum0, old_port0, new_port0,
+					 ip4_header_t /* cheat */ ,
+					 length /* changed member */ );
+		  udp0->checksum = ip_csum_fold (sum0);
+		}
 	      udp_packets++;
 	    }
 
@@ -1264,12 +1271,11 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
 				 src_address /* changed member */ );
 	  ip1->checksum = ip_csum_fold (sum1);
 
+	  old_port1 = udp1->src_port;
+	  new_port1 = udp1->src_port = s1->out2in.port;
+
 	  if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
 	    {
-	      old_port1 = tcp1->src_port;
-	      tcp1->src_port = s1->out2in.port;
-	      new_port1 = tcp1->src_port;
-
 	      sum1 = tcp1->checksum;
 	      sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
 				     ip4_header_t,
@@ -1283,9 +1289,17 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
 	    }
 	  else
 	    {
-	      old_port1 = udp1->src_port;
-	      udp1->src_port = s1->out2in.port;
-	      udp1->checksum = 0;
+	      if (PREDICT_FALSE (udp1->checksum))
+		{
+		  sum1 = udp1->checksum;
+		  sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
+					 ip4_header_t,
+					 dst_address /* changed member */ );
+		  sum1 = ip_csum_update (sum1, old_port1, new_port1,
+					 ip4_header_t /* cheat */ ,
+					 length /* changed member */ );
+		  udp1->checksum = ip_csum_fold (sum1);
+		}
 	      udp_packets++;
 	    }
 
@@ -1488,12 +1502,11 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
 				 src_address /* changed member */ );
 	  ip0->checksum = ip_csum_fold (sum0);
 
+	  old_port0 = udp0->src_port;
+	  new_port0 = udp0->src_port = s0->out2in.port;
+
 	  if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
 	    {
-	      old_port0 = tcp0->src_port;
-	      tcp0->src_port = s0->out2in.port;
-	      new_port0 = tcp0->src_port;
-
 	      sum0 = tcp0->checksum;
 	      sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 				     ip4_header_t,
@@ -1507,9 +1520,17 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
 	    }
 	  else
 	    {
-	      old_port0 = udp0->src_port;
-	      udp0->src_port = s0->out2in.port;
-	      udp0->checksum = 0;
+	      if (PREDICT_FALSE (udp0->checksum))
+		{
+		  sum0 = udp0->checksum;
+		  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+					 ip4_header_t,
+					 dst_address /* changed member */ );
+		  sum0 = ip_csum_update (sum0, old_port0, new_port0,
+					 ip4_header_t /* cheat */ ,
+					 length /* changed member */ );
+		  udp0->checksum = ip_csum_fold (sum0);
+		}
 	      udp_packets++;
 	    }
 
@@ -1869,12 +1890,11 @@ VLIB_NODE_FN (nat44_in2out_reass_node) (vlib_main_t * vm,
 
 	  if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
 	    {
+	      old_port0 = udp0->src_port;
+	      new_port0 = udp0->src_port = s0->out2in.port;
+
 	      if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
 		{
-		  old_port0 = tcp0->src_port;
-		  tcp0->src_port = s0->out2in.port;
-		  new_port0 = tcp0->src_port;
-
 		  sum0 = tcp0->checksum;
 		  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 					 ip4_header_t,
@@ -1884,11 +1904,16 @@ VLIB_NODE_FN (nat44_in2out_reass_node) (vlib_main_t * vm,
 					 length /* changed member */ );
 		  tcp0->checksum = ip_csum_fold (sum0);
 		}
-	      else
+	      else if (PREDICT_FALSE (udp0->checksum))
 		{
-		  old_port0 = udp0->src_port;
-		  udp0->src_port = s0->out2in.port;
-		  udp0->checksum = 0;
+		  sum0 = udp0->checksum;
+		  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+					 ip4_header_t,
+					 dst_address /* changed member */ );
+		  sum0 = ip_csum_update (sum0, old_port0, new_port0,
+					 ip4_header_t /* cheat */ ,
+					 length /* changed member */ );
+		  udp0->checksum = ip_csum_fold (sum0);
 		}
 	    }
 
@@ -2099,11 +2124,11 @@ VLIB_NODE_FN (snat_in2out_fast_node) (vlib_main_t * vm,
 
 	  if (PREDICT_FALSE (new_port0 != udp0->dst_port))
 	    {
+	      old_port0 = udp0->src_port;
+	      udp0->src_port = new_port0;
+
 	      if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
 		{
-		  old_port0 = tcp0->src_port;
-		  tcp0->src_port = new_port0;
-
 		  sum0 = tcp0->checksum;
 		  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 					 ip4_header_t,
@@ -2114,11 +2139,16 @@ VLIB_NODE_FN (snat_in2out_fast_node) (vlib_main_t * vm,
 		  mss_clamping (sm, tcp0, &sum0);
 		  tcp0->checksum = ip_csum_fold (sum0);
 		}
-	      else
+	      else if (udp0->checksum)
 		{
-		  old_port0 = udp0->src_port;
-		  udp0->src_port = new_port0;
-		  udp0->checksum = 0;
+		  sum0 = udp0->checksum;
+		  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+					 ip4_header_t,
+					 dst_address /* changed member */ );
+		  sum0 = ip_csum_update (sum0, old_port0, new_port0,
+					 ip4_header_t /* cheat */ ,
+					 length /* changed member */ );
+		  udp0->checksum = ip_csum_fold (sum0);
 		}
 	    }
 	  else
@@ -2132,6 +2162,14 @@ VLIB_NODE_FN (snat_in2out_fast_node) (vlib_main_t * vm,
 		  mss_clamping (sm, tcp0, &sum0);
 		  tcp0->checksum = ip_csum_fold (sum0);
 		}
+	      else if (udp0->checksum)
+		{
+		  sum0 = udp0->checksum;
+		  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+					 ip4_header_t,
+					 dst_address /* changed member */ );
+		  udp0->checksum = ip_csum_fold (sum0);
+		}
 	    }
 
 	  /* Hairpinning */