NAT44: interface output feature and service host direct access (VPP-1176)

forwarding mode:
session initiaded from service host - translate
session initiaded from remote host - do not translate

Change-Id: I48170ee8e4ad14d3d3083ee31a40ef8d10d6ff32
Signed-off-by: Matus Fabian <matfabia@cisco.com>
(cherry picked from commit 204591d1bd754f6086edcf8b27a95beab929a78f)

3 files changed, 161 insertions, 6 deletions

diff --git a/src/plugins/nat/in2out.c b/src/plugins/nat/in2out.c
index fae930b607f..134d652feb0 100755
--- a/src/plugins/nat/in2out.c
+++ b/src/plugins/nat/in2out.c
@@ -464,6 +464,47 @@ icmp_get_ed_key(ip4_header_t *ip0, nat_ed_ses_key_t *p_key0)
   return 0;
 }
 
+static inline int
+nat_not_translate_output_feature_fwd (snat_main_t * sm, ip4_header_t * ip)
+{
+  nat_ed_ses_key_t key;
+  clib_bihash_kv_16_8_t kv, value;
+  udp_header_t *udp;
+
+  if (!sm->forwarding_enabled)
+    return 0;
+
+  if (ip->protocol == IP_PROTOCOL_ICMP)
+    {
+      if (icmp_get_ed_key (ip, &key))
+        return 0;
+    }
+  else if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
+    {
+      udp = ip4_next_header(ip);
+      key.l_addr = ip->src_address;
+      key.r_addr = ip->dst_address;
+      key.proto = ip->protocol;
+      key.r_port = udp->dst_port;
+      key.l_port = udp->src_port;
+    }
+  else
+    {
+      key.l_addr = ip->src_address;
+      key.r_addr = ip->dst_address;
+      key.proto = ip->protocol;
+      key.l_port = key.r_port = 0;
+    }
+  key.fib_index = 0;
+  kv.key[0] = key.as_u64[0];
+  kv.key[1] = key.as_u64[1];
+
+  if (!clib_bihash_search_16_8 (&sm->in2out_ed, &kv, &value))
+    return value.value == ~0ULL;
+
+  return 0;
+}
+
 /**
  * Get address and port values to be used for ICMP packet translation
  * and create session if needed
@@ -1283,6 +1324,8 @@ snat_in2out_lb (snat_main_t *sm,
 
   if (!clib_bihash_search_16_8 (&sm->in2out_ed, &s_kv, &s_value))
     {
+      if (s_value.value == ~0ULL)
+        return 0;
       s = pool_elt_at_index (tsm->sessions, s_value.value);
     }
   else
@@ -1517,6 +1560,12 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
             }
           else
             {
+              if (is_output_feature)
+                {
+                  if (PREDICT_FALSE(nat_not_translate_output_feature_fwd(sm, ip0)))
+                    goto trace00;
+                }
+
               if (PREDICT_FALSE (proto0 == ~0 || proto0 == SNAT_PROTOCOL_ICMP))
                 {
                   next0 = SNAT_IN2OUT_NEXT_SLOW_PATH;
@@ -1703,6 +1752,12 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
             }
           else
             {
+              if (is_output_feature)
+                {
+                  if (PREDICT_FALSE(nat_not_translate_output_feature_fwd(sm, ip1)))
+                    goto trace01;
+                }
+
               if (PREDICT_FALSE (proto1 == ~0 || proto1 == SNAT_PROTOCOL_ICMP))
                 {
                   next1 = SNAT_IN2OUT_NEXT_SLOW_PATH;
@@ -1716,8 +1771,6 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
                 }
             }
 
-          b1->flags |= VNET_BUFFER_F_IS_NATED;
-
           key1.addr = ip1->src_address;
           key1.port = udp1->src_port;
           key1.protocol = proto1;
@@ -1780,6 +1833,8 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
                 }
             }
 
+          b1->flags |= VNET_BUFFER_F_IS_NATED;
+
           old_addr1 = ip1->src_address.as_u32;
           ip1->src_address = s1->out2in.addr;
           new_addr1 = ip1->src_address.as_u32;
@@ -1925,6 +1980,12 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
             }
           else
             {
+               if (is_output_feature)
+                {
+                  if (PREDICT_FALSE(nat_not_translate_output_feature_fwd(sm, ip0)))
+                    goto trace0;
+                }
+
               if (PREDICT_FALSE (proto0 == ~0 || proto0 == SNAT_PROTOCOL_ICMP))
                 {
                   next0 = SNAT_IN2OUT_NEXT_SLOW_PATH;
diff --git a/src/plugins/nat/out2in.c b/src/plugins/nat/out2in.c
index 7f500a916f0..11e39ec07a8 100755
--- a/src/plugins/nat/out2in.c
+++ b/src/plugins/nat/out2in.c
@@ -311,6 +311,43 @@ icmp_get_ed_key(ip4_header_t *ip0, nat_ed_ses_key_t *p_key0)
   return 0;
 }
 
+static void
+create_bypass_for_fwd(snat_main_t * sm, ip4_header_t * ip)
+{
+  nat_ed_ses_key_t key;
+  clib_bihash_kv_16_8_t kv;
+  udp_header_t *udp;
+
+  if (ip->protocol == IP_PROTOCOL_ICMP)
+    {
+      if (icmp_get_ed_key (ip, &key))
+        return;
+    }
+  else if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
+    {
+      udp = ip4_next_header(ip);
+      key.r_addr = ip->src_address;
+      key.l_addr = ip->dst_address;
+      key.proto = ip->protocol;
+      key.l_port = udp->dst_port;
+      key.r_port = udp->src_port;
+    }
+  else
+    {
+      key.r_addr = ip->src_address;
+      key.l_addr = ip->dst_address;
+      key.proto = ip->protocol;
+      key.l_port = key.r_port = 0;
+    }
+  key.fib_index = 0;
+  kv.key[0] = key.as_u64[0];
+  kv.key[1] = key.as_u64[1];
+  kv.value = ~0ULL;
+
+  if (clib_bihash_add_del_16_8 (&sm->in2out_ed, &kv, 1))
+    clib_warning ("in2out_ed key add failed");
+}
+
 /**
  * Get address and port values to be used for ICMP packet translation
  * and create session if needed
@@ -382,6 +419,7 @@ u32 icmp_match_out2in_slow(snat_main_t *sm, vlib_node_runtime_t *node,
             }
           else
             {
+              create_bypass_for_fwd(sm, ip0);
               dont_translate = 1;
               goto out;
             }
@@ -1112,7 +1150,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
                       goto trace0;
                     }
                   else
-                    goto trace0;
+                    {
+                      create_bypass_for_fwd(sm, ip0);
+                      goto trace0;
+                    }
                 }
 
               /* Create session initiated by host from external network */
@@ -1275,7 +1316,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
                       goto trace1;
                     }
                   else
-                    goto trace1;
+                    {
+                      create_bypass_for_fwd(sm, ip1);
+                      goto trace1;
+                    }
                 }
 
               /* Create session initiated by host from external network */
@@ -1474,7 +1518,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
                       goto trace00;
                     }
                   else
-                    goto trace00;
+                    {
+                      create_bypass_for_fwd(sm, ip0);
+                      goto trace00;
+                    }
                 }
 
               /* Create session initiated by host from external network */
@@ -1714,7 +1761,10 @@ nat44_out2in_reass_node_fn (vlib_main_t * vm,
                           goto trace0;
                         }
                       else
-                        goto trace0;
+                        {
+                          create_bypass_for_fwd(sm, ip0);
+                          goto trace0;
+                        }
                     }
 
                   /* Create session initiated by host from external network */
diff --git a/test/test_nat.py b/test/test_nat.py
index c89180609fe..f039faf84fe 100644
--- a/test/test_nat.py
+++ b/test/test_nat.py
@@ -2697,6 +2697,50 @@ class TestNAT44(MethodHolder):
             self.logger.error(ppp("Unexpected or invalid packet:"), p)
             raise
 
+    def test_output_feature_and_service2(self):
+        """ NAT44 interface output feature and service host direct access """
+        self.vapi.nat44_forwarding_enable_disable(1)
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
+
+        # session initiaded from service host - translate
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
+
+        pkts = self.create_stream_out(self.pg1)
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
+
+        tcp_port_out = self.tcp_port_out
+        udp_port_out = self.udp_port_out
+        icmp_id_out = self.icmp_id_out
+
+        # session initiaded from remote host - do not translate
+        pkts = self.create_stream_out(self.pg1,
+                                      self.pg0.remote_ip4,
+                                      use_inside_ports=True)
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
+
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture, nat_ip=self.pg0.remote_ip4,
+                                same_port=True)
+
     def test_one_armed_nat44(self):
         """ One armed NAT44 """
         remote_host = self.pg9.remote_hosts[0]