snat: Hairpinning (VPP-444)

Change-Id: I73881ef32d547852da96e77402a1758f37e812d5
Signed-off-by: Matus Fabian <matfabia@cisco.com>

1 files changed, 67 insertions, 0 deletions

diff --git a/test/test_snat.py b/test/test_snat.py
index e90d9c0b71d..5cc76f6c7da 100644
--- a/test/test_snat.py
+++ b/test/test_snat.py
@@ -34,6 +34,9 @@ class TestSNAT(VppTestCase):
                 i.config_ip4()
                 i.resolve_arp()
 
+            cls.pg0.generate_remote_hosts(2)
+            cls.pg0.configure_ipv4_neighbors()
+
             cls.overlapping_interfaces = list(list(cls.pg_interfaces[4:7]))
 
             for i in cls.overlapping_interfaces:
@@ -526,6 +529,70 @@ class TestSNAT(VppTestCase):
         capture = self.pg6.get_capture()
         self.verify_capture_in(capture, self.pg6)
 
+    def test_hairpinning(self):
+        """ SNAT hairpinning """
+
+        host = self.pg0.remote_hosts[0]
+        server = self.pg0.remote_hosts[1]
+        host_in_port = 1234
+        host_out_port = 0
+        server_in_port = 5678
+        server_out_port = 8765
+
+        self.snat_add_address(self.snat_addr)
+        self.vapi.snat_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.snat_interface_add_del_feature(self.pg1.sw_if_index,
+                                                 is_inside=0)
+        # add static mapping for server
+        self.snat_add_static_mapping(server.ip4, self.snat_addr,
+                                     server_in_port, server_out_port)
+
+        # send packet from host to server
+        p = (Ether(src=host.mac, dst=self.pg0.local_mac) /
+             IP(src=host.ip4, dst=self.snat_addr) /
+             TCP(sport=host_in_port, dport=server_out_port))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture()
+        self.assertEqual(1, len(capture))
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.snat_addr)
+            self.assertEqual(ip.dst, server.ip4)
+            self.assertNotEqual(tcp.sport, host_in_port)
+            self.assertEqual(tcp.dport, server_in_port)
+            host_out_port = tcp.sport
+        except:
+            error("Unexpected or invalid packet:")
+            error(p.show())
+            raise
+
+        # send reply from server to host
+        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
+             IP(src=server.ip4, dst=self.snat_addr) /
+             TCP(sport=server_in_port, dport=host_out_port))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture()
+        self.assertEqual(1, len(capture))
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.snat_addr)
+            self.assertEqual(ip.dst, host.ip4)
+            self.assertEqual(tcp.sport, server_out_port)
+            self.assertEqual(tcp.dport, host_in_port)
+        except:
+            error("Unexpected or invalid packet:")
+            error(p.show())
+            raise
+
+
     def tearDown(self):
         super(TestSNAT, self).tearDown()
         if not self.vpp_dead: