nat: Revert "nat: respect udp checksum"

This reverts commit 80276a7101f23ddd7207983f48f85422daf2cb7f.

The commit in master was found to be wrong, was reverted, and replaced by 16572355c9069e2e8e4836dc6bd6a65feed2d390

This reverts the corresponding commit in stable/1908, to replace with the correct fix.

Type: fix
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
Change-Id: Idc27c0d81edf2263e523088f7ee7b66655db20f1

1 files changed, 27 insertions, 33 deletions

diff --git a/src/plugins/nat/nat_det_out2in.c b/src/plugins/nat/nat_det_out2in.c
index c4bd096deb1..45fba18b248 100644
--- a/src/plugins/nat/nat_det_out2in.c
+++ b/src/plugins/nat/nat_det_out2in.c
@@ -343,8 +343,7 @@ VLIB_NODE_FN (snat_det_out2in_node) (vlib_main_t * vm,
 	      b0->error = node->errors[NAT_DET_OUT2IN_ERROR_NO_TRANSLATION];
 	      goto trace0;
 	    }
-	  old_port0 = udp0->dst_port;
-	  udp0->dst_port = new_port0 = ses0->in_port;
+	  new_port0 = ses0->in_port;
 
 	  old_addr0 = ip0->dst_address;
 	  ip0->dst_address = new_addr0;
@@ -365,25 +364,24 @@ VLIB_NODE_FN (snat_det_out2in_node) (vlib_main_t * vm,
 		       && ses0->state == SNAT_SESSION_TCP_LAST_ACK)
 		snat_det_ses_close (dm0, ses0);
 
+	      old_port0 = tcp0->dst;
+	      tcp0->dst = new_port0;
+
 	      sum0 = tcp0->checksum;
 	      sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
 				     ip4_header_t,
 				     dst_address /* changed member */ );
+
 	      sum0 = ip_csum_update (sum0, old_port0, new_port0,
 				     ip4_header_t /* cheat */ ,
 				     length /* changed member */ );
 	      tcp0->checksum = ip_csum_fold (sum0);
 	    }
-	  else if (udp0->checksum)
+	  else
 	    {
-	      sum0 = udp0->checksum;
-	      sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
-				     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);
+	      old_port0 = udp0->dst_port;
+	      udp0->dst_port = new_port0;
+	      udp0->checksum = 0;
 	    }
 
 	trace0:
@@ -464,8 +462,7 @@ VLIB_NODE_FN (snat_det_out2in_node) (vlib_main_t * vm,
 	      b1->error = node->errors[NAT_DET_OUT2IN_ERROR_NO_TRANSLATION];
 	      goto trace1;
 	    }
-	  old_port1 = udp1->dst_port;
-	  udp1->dst_port = new_port1 = ses1->in_port;
+	  new_port1 = ses1->in_port;
 
 	  old_addr1 = ip1->dst_address;
 	  ip1->dst_address = new_addr1;
@@ -486,25 +483,24 @@ VLIB_NODE_FN (snat_det_out2in_node) (vlib_main_t * vm,
 		       && ses1->state == SNAT_SESSION_TCP_LAST_ACK)
 		snat_det_ses_close (dm1, ses1);
 
+	      old_port1 = tcp1->dst;
+	      tcp1->dst = new_port1;
+
 	      sum1 = tcp1->checksum;
 	      sum1 = ip_csum_update (sum1, old_addr1.as_u32, new_addr1.as_u32,
 				     ip4_header_t,
 				     dst_address /* changed member */ );
+
 	      sum1 = ip_csum_update (sum1, old_port1, new_port1,
 				     ip4_header_t /* cheat */ ,
 				     length /* changed member */ );
 	      tcp1->checksum = ip_csum_fold (sum1);
 	    }
-	  else if (udp1->checksum)
+	  else
 	    {
-	      sum1 = udp1->checksum;
-	      sum1 = ip_csum_update (sum1, old_addr1.as_u32, new_addr1.as_u32,
-				     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);
+	      old_port1 = udp1->dst_port;
+	      udp1->dst_port = new_port1;
+	      udp1->checksum = 0;
 	    }
 
 	trace1:
@@ -618,8 +614,7 @@ VLIB_NODE_FN (snat_det_out2in_node) (vlib_main_t * vm,
 	      b0->error = node->errors[NAT_DET_OUT2IN_ERROR_NO_TRANSLATION];
 	      goto trace00;
 	    }
-	  old_port0 = udp0->dst_port;
-	  udp0->dst_port = new_port0 = ses0->in_port;
+	  new_port0 = ses0->in_port;
 
 	  old_addr0 = ip0->dst_address;
 	  ip0->dst_address = new_addr0;
@@ -640,25 +635,24 @@ VLIB_NODE_FN (snat_det_out2in_node) (vlib_main_t * vm,
 		       && ses0->state == SNAT_SESSION_TCP_LAST_ACK)
 		snat_det_ses_close (dm0, ses0);
 
+	      old_port0 = tcp0->dst;
+	      tcp0->dst = new_port0;
+
 	      sum0 = tcp0->checksum;
 	      sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
 				     ip4_header_t,
 				     dst_address /* changed member */ );
+
 	      sum0 = ip_csum_update (sum0, old_port0, new_port0,
 				     ip4_header_t /* cheat */ ,
 				     length /* changed member */ );
 	      tcp0->checksum = ip_csum_fold (sum0);
 	    }
-	  else if (udp0->checksum)
+	  else
 	    {
-	      sum0 = udp0->checksum;
-	      sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
-				     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);
+	      old_port0 = udp0->dst_port;
+	      udp0->dst_port = new_port0;
+	      udp0->checksum = 0;
 	    }
 
 	trace00: