npt66: checksum applied to src address instead of dst address on rx

Applied the checksum delta to the source address instead of the destination address
in the RX direction.

Cleaned up tests a little.

Type: fix
Change-Id: I871f3448365587e5319dfbca6ea356935321ff9b
Signed-off-by: Ole Troan <otroan@employees.org>

2 files changed, 28 insertions, 21 deletions

diff --git a/src/plugins/npt66/npt66_node.c b/src/plugins/npt66/npt66_node.c
index 95fe8594dbb..21dddee3951 100644
--- a/src/plugins/npt66/npt66_node.c
+++ b/src/plugins/npt66/npt66_node.c
@@ -121,7 +121,6 @@ static int
 npt66_translate (ip6_header_t *ip, npt66_binding_t *binding, int dir)
 {
   int rv = 0;
-  clib_warning ("npt66_translate: before: %U", format_ip6_header, ip, 40);
   if (dir == VLIB_TX)
     {
       if (!ip6_prefix_cmp (ip->src_address, binding->internal,
@@ -147,9 +146,8 @@ npt66_translate (ip6_header_t *ip, npt66_binding_t *binding, int dir)
       ip->dst_address = ip6_prefix_copy (ip->dst_address, binding->internal,
 					 binding->internal_plen);
       rv = npt66_adjust_checksum (binding->internal_plen, true, binding->delta,
-				  &ip->src_address);
+				  &ip->dst_address);
     }
-  clib_warning ("npt66_translate: after: %U", format_ip6_header, ip, 40);
 done:
   return rv;
 }
diff --git a/test/test_npt66.py b/test/test_npt66.py
index 5173c62d44f..6565c38aae0 100644
--- a/test/test_npt66.py
+++ b/test/test_npt66.py
@@ -29,35 +29,43 @@ class TestNPT66(VppTestCase):
             i.admin_down()
         super(TestNPT66, self).tearDown()
 
-    def send_and_verify(self, in2out, internal, external):
-        if in2out:
-            sendif = self.pg0
-            recvif = self.pg1
-            local_mac = self.pg0.local_mac
-            remote_mac = self.pg0.remote_mac
-            src = ipaddress.ip_interface(internal).ip + 1
-            dst = self.pg1.remote_ip6
-        else:
-            sendif = self.pg1
-            recvif = self.pg0
-            local_mac = self.pg1.local_mac
-            remote_mac = self.pg1.remote_mac
-            src = self.pg1.remote_ip6
-            dst = ipaddress.ip_interface(external).ip + 1
+    def send_and_verify(self, internal):
+        sendif = self.pg0
+        recvif = self.pg1
+        local_mac = self.pg0.local_mac
+        remote_mac = self.pg0.remote_mac
+        src = ipaddress.ip_interface(internal).ip + 1
+        dst = self.pg1.remote_ip6
 
         p = (
             Ether(dst=local_mac, src=remote_mac)
             / IPv6(src=src, dst=dst)
             / ICMPv6EchoRequest()
+            / Raw(b"Request")
         )
         rxs = self.send_and_expect(sendif, p, recvif)
         for rx in rxs:
-            rx.show2()
             original_cksum = rx[ICMPv6EchoRequest].cksum
             del rx[ICMPv6EchoRequest].cksum
             rx = rx.__class__(bytes(rx))
             self.assertEqual(original_cksum, rx[ICMPv6EchoRequest].cksum)
 
+            # Generate a replies
+            reply = (
+                Ether(dst=rx[Ether].src, src=local_mac)
+                / IPv6(src=rx[IPv6].dst, dst=rx[IPv6].src)
+                / ICMPv6EchoRequest()
+                / Raw(b"Reply")
+            )
+
+            replies = self.send_and_expect(recvif, reply, sendif)
+            for r in replies:
+                self.assertEqual(str(p[IPv6].src), r[IPv6].dst)
+                original_cksum = r[ICMPv6EchoRequest].cksum
+                del r[ICMPv6EchoRequest].cksum
+                r = r.__class__(bytes(r))
+                self.assertEqual(original_cksum, r[ICMPv6EchoRequest].cksum)
+
     def do_test(self, internal, external):
         self.vapi.npt66_binding_add_del(
             sw_if_index=self.pg1.sw_if_index,
@@ -65,10 +73,10 @@ class TestNPT66(VppTestCase):
             external=external,
             is_add=True,
         )
+        ## TODO use route api
         self.vapi.cli(f"ip route add {internal} via {self.pg0.remote_ip6}")
 
-        self.send_and_verify(True, internal, external)
-        self.send_and_verify(False, internal, external)
+        self.send_and_verify(internal)
 
         self.vapi.npt66_binding_add_del(
             sw_if_index=self.pg1.sw_if_index,
@@ -80,6 +88,7 @@ class TestNPT66(VppTestCase):
     def test_npt66_simple(self):
         """Send and receive a packet through NPT66"""
 
+        self.do_test("fd00:0000:0000::/48", "2001:4650:c3ed::/48")
         self.do_test("fc00:1::/48", "2001:db8:1::/48")
         self.do_test("fc00:1234::/32", "2001:db8:1::/32")
         self.do_test("fc00:1234::/63", "2001:db8:1::/56")