VPP-339: SNAT static mapping

1:1 NAT
1:1 NAT with ports
1:1 NAT static mapping only - add "static mapping only [connection tracking]"
                              to snat startup config

Change-Id: I37cd06a9d71d1943eb6618034d7c547c4a9348c4
Signed-off-by: Matus Fabian <matfabia@cisco.com>

1 files changed, 468 insertions, 42 deletions

diff --git a/plugins/snat-plugin/snat/out2in.c b/plugins/snat-plugin/snat/out2in.c
index 861dae63b0a..b3497c40d31 100644
--- a/plugins/snat-plugin/snat/out2in.c
+++ b/plugins/snat-plugin/snat/out2in.c
@@ -25,8 +25,6 @@
 #include <vppinfra/error.h>
 #include <vppinfra/elog.h>
 
-vlib_node_registration_t snat_out2in_node;
-
 typedef struct {
   u32 sw_if_index;
   u32 next_index;
@@ -45,7 +43,20 @@ static u8 * format_snat_out2in_trace (u8 * s, va_list * args)
   return s;
 }
 
+static u8 * format_snat_out2in_fast_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  snat_out2in_trace_t * t = va_arg (*args, snat_out2in_trace_t *);
+  
+  s = format (s, "SNAT_OUT2IN_FAST: sw_if_index %d, next index %d",
+              t->sw_if_index, t->next_index);
+  return s;
+}
+
+
 vlib_node_registration_t snat_out2in_node;
+vlib_node_registration_t snat_out2in_fast_node;
 
 #define foreach_snat_out2in_error                       \
 _(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
@@ -71,6 +82,101 @@ typedef enum {
   SNAT_OUT2IN_N_NEXT,
 } snat_out2in_next_t;
 
+/**
+ * @brief Create session for static mapping.
+ *
+ * Create NAT session initiated by host from external network with static
+ * mapping.
+ *
+ * @param sm     SNAT main.
+ * @param b0     Vlib buffer.
+ * @param in2out In2out SNAT session key.
+ * @param out2in Out2in SNAT session key.
+ * @param node   Vlib node.
+ *
+ * @returns SNAT session if successfully created otherwise 0.
+ */
+static inline snat_session_t *
+create_session_for_static_mapping (snat_main_t *sm,
+                                   vlib_buffer_t *b0,
+                                   snat_session_key_t in2out,
+                                   snat_session_key_t out2in,
+                                   vlib_node_runtime_t * node)
+{
+  snat_user_t *u;
+  snat_user_key_t user_key;
+  snat_session_t *s;
+  clib_bihash_kv_8_8_t kv0, value0;
+  dlist_elt_t * per_user_translation_list_elt;
+  dlist_elt_t * per_user_list_head_elt;
+
+  user_key.addr = in2out.addr;
+  user_key.fib_index = in2out.fib_index;
+  kv0.key = user_key.as_u64;
+
+  /* Ever heard of the "user" = inside ip4 address before? */
+  if (clib_bihash_search_8_8 (&sm->user_hash, &kv0, &value0))
+    {
+      /* no, make a new one */
+      pool_get (sm->users, u);
+      memset (u, 0, sizeof (*u));
+      u->addr = in2out.addr;
+
+      pool_get (sm->list_pool, per_user_list_head_elt);
+
+      u->sessions_per_user_list_head_index = per_user_list_head_elt -
+        sm->list_pool;
+
+      clib_dlist_init (sm->list_pool, u->sessions_per_user_list_head_index);
+
+      kv0.value = u - sm->users;
+
+      /* add user */
+      clib_bihash_add_del_8_8 (&sm->user_hash, &kv0, 1 /* is_add */);
+    }
+  else
+    {
+      u = pool_elt_at_index (sm->users, value0.value);
+    }
+
+  pool_get (sm->sessions, s);
+  memset (s, 0, sizeof (*s));
+
+  s->outside_address_index = ~0;
+  s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
+  u->nstaticsessions++;
+
+  /* Create list elts */
+  pool_get (sm->list_pool, per_user_translation_list_elt);
+  clib_dlist_init (sm->list_pool, per_user_translation_list_elt -
+                   sm->list_pool);
+
+  per_user_translation_list_elt->value = s - sm->sessions;
+  s->per_user_index = per_user_translation_list_elt - sm->list_pool;
+  s->per_user_list_head_index = u->sessions_per_user_list_head_index;
+
+  clib_dlist_addtail (sm->list_pool, s->per_user_list_head_index,
+                      per_user_translation_list_elt - sm->list_pool);
+
+  s->in2out = in2out;
+  s->out2in = out2in;
+  s->in2out.protocol = out2in.protocol;
+
+  /* Add to translation hashes */
+  kv0.key = s->in2out.as_u64;
+  kv0.value = s - sm->sessions;
+  if (clib_bihash_add_del_8_8 (&sm->in2out, &kv0, 1 /* is_add */))
+      clib_warning ("in2out key add failed");
+
+  kv0.key = s->out2in.as_u64;
+  kv0.value = s - sm->sessions;
+
+  if (clib_bihash_add_del_8_8 (&sm->out2in, &kv0, 1 /* is_add */))
+      clib_warning ("out2in key add failed");
+
+  return s;
+}
+
 static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
                                          vlib_buffer_t * b0,
                                          ip4_header_t * ip0,
@@ -80,7 +186,7 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
                                          vlib_node_runtime_t * node,
                                          u32 next0, f64 now)
 {
-  snat_session_key_t key0;
+  snat_session_key_t key0, sm0;
   icmp_echo_header_t *echo0;
   clib_bihash_kv_8_8_t kv0, value0;
   snat_session_t * s0;
@@ -100,24 +206,35 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
   
   if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
     {
-      ip4_address_t * first_int_addr;
-
-      if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+      /* Try to match static mapping by external address and port,
+         destination address and port in packet */
+      if (snat_static_mapping_match(sm, key0, &sm0, 1))
         {
-          first_int_addr = 
-            ip4_interface_first_address (sm->ip4_main, sw_if_index0,
-                                         0 /* just want the address */);
-          rt->cached_sw_if_index = sw_if_index0;
-          rt->cached_ip4_address = first_int_addr->as_u32;
+           ip4_address_t * first_int_addr;
+
+          if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+            {
+              first_int_addr = 
+                ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                             0 /* just want the address */);
+              rt->cached_sw_if_index = sw_if_index0;
+              rt->cached_ip4_address = first_int_addr->as_u32;
+            }
+          
+          /* Don't NAT packet aimed at the intfc address */
+          if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                            rt->cached_ip4_address))
+            return next0;
+
+          b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+          return SNAT_OUT2IN_NEXT_DROP;
         }
-      
-      /* Don't NAT packet aimed at the intfc address */
-      if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
-                        rt->cached_ip4_address))
-        return next0;
 
-      b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-      return SNAT_OUT2IN_NEXT_DROP;
+      /* Create session initiated by host from external network */
+      s0 = create_session_for_static_mapping(sm, b0, sm0, key0,
+                                             node);
+      if (!s0)
+        return SNAT_OUT2IN_NEXT_DROP;
     }
   else
     s0 = pool_elt_at_index (sm->sessions, value0.value);
@@ -142,13 +259,17 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
                          identifier);
   icmp0->checksum = ip_csum_fold (sum0);
 
-  /* Accounting, per-user LRU list maintenance */
+  /* Accounting */
   s0->last_heard = now;
   s0->total_pkts++;
   s0->total_bytes += vlib_buffer_length_in_chain (sm->vlib_main, b0);
-  clib_dlist_remove (sm->list_pool, s0->per_user_index);
-  clib_dlist_addtail (sm->list_pool, s0->per_user_list_head_index,
-                      s0->per_user_index);
+  /* Per-user LRU list maintenance for dynamic translation */
+  if (!snat_is_session_static (s0))
+    {
+      clib_dlist_remove (sm->list_pool, s0->per_user_index);
+      clib_dlist_addtail (sm->list_pool, s0->per_user_list_head_index,
+                          s0->per_user_index);
+    }
 
   return next0;
 }
@@ -193,7 +314,7 @@ snat_out2in_node_fn (vlib_main_t * vm,
           udp_header_t * udp0, * udp1;
           tcp_header_t * tcp0, * tcp1;
           icmp46_header_t * icmp0, * icmp1;
-          snat_session_key_t key0, key1;
+          snat_session_key_t key0, key1, sm0, sm1;
           u32 rx_fib_index0, rx_fib_index1;
           u32 proto0, proto1;
           snat_session_t * s0 = 0, * s1 = 0;
@@ -264,14 +385,27 @@ snat_out2in_node_fn (vlib_main_t * vm,
           kv0.key = key0.as_u64;
 
           if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
-            goto trace0;
+            {
+              /* Try to match static mapping by external address and port,
+                 destination address and port in packet */
+              if (snat_static_mapping_match(sm, key0, &sm0, 1))
+                {
+                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  goto trace0;
+                }
+
+              /* Create session initiated by host from external network */
+              s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node);
+              if (!s0)
+                goto trace0;
+            }
           else
             s0 = pool_elt_at_index (sm->sessions, value0.value);
 
           old_addr0 = ip0->dst_address.as_u32;
           ip0->dst_address = s0->in2out.addr;
           new_addr0 = ip0->dst_address.as_u32;
-          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
 
           sum0 = ip0->checksum;
           sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
@@ -302,13 +436,17 @@ snat_out2in_node_fn (vlib_main_t * vm,
               udp0->checksum = 0;
             }
 
-          /* Accounting, per-user LRU list maintenance */
+          /* Accounting */
           s0->last_heard = now;
           s0->total_pkts++;
           s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
-          clib_dlist_remove (sm->list_pool, s0->per_user_index);
-          clib_dlist_addtail (sm->list_pool, s0->per_user_list_head_index,
-                              s0->per_user_index);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s0))
+            {
+              clib_dlist_remove (sm->list_pool, s0->per_user_index);
+              clib_dlist_addtail (sm->list_pool, s0->per_user_list_head_index,
+                                  s0->per_user_index);
+            }
         trace0:
 
           if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
@@ -366,14 +504,27 @@ snat_out2in_node_fn (vlib_main_t * vm,
           kv1.key = key1.as_u64;
 
           if (clib_bihash_search_8_8 (&sm->out2in, &kv1, &value1))
-            goto trace1;
+            {
+              /* Try to match static mapping by external address and port,
+                 destination address and port in packet */
+              if (snat_static_mapping_match(sm, key1, &sm1, 1))
+                {
+                  b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  goto trace1;
+                }
+
+              /* Create session initiated by host from external network */
+              s1 = create_session_for_static_mapping(sm, b1, sm1, key1, node);
+              if (!s1)
+                goto trace1;
+            }
           else
             s1 = pool_elt_at_index (sm->sessions, value1.value);
 
           old_addr1 = ip1->dst_address.as_u32;
           ip1->dst_address = s1->in2out.addr;
           new_addr1 = ip1->dst_address.as_u32;
-          vnet_buffer(b1)->sw_if_index[VLIB_TX] = s1->out2in.fib_index;
+          vnet_buffer(b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
 
           sum1 = ip1->checksum;
           sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
@@ -404,13 +555,17 @@ snat_out2in_node_fn (vlib_main_t * vm,
               udp1->checksum = 0;
             }
 
-          /* Accounting, per-user LRU list maintenance */
+          /* Accounting */
           s1->last_heard = now;
           s1->total_pkts++;
           s1->total_bytes += vlib_buffer_length_in_chain (vm, b1);
-          clib_dlist_remove (sm->list_pool, s1->per_user_index);
-          clib_dlist_addtail (sm->list_pool, s1->per_user_list_head_index,
-                              s1->per_user_index);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s1))
+            {
+              clib_dlist_remove (sm->list_pool, s1->per_user_index);
+              clib_dlist_addtail (sm->list_pool, s1->per_user_list_head_index,
+                                  s1->per_user_index);
+            }
         trace1:
 
           if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
@@ -447,7 +602,7 @@ snat_out2in_node_fn (vlib_main_t * vm,
           udp_header_t * udp0;
           tcp_header_t * tcp0;
           icmp46_header_t * icmp0;
-          snat_session_key_t key0;
+          snat_session_key_t key0, sm0;
           u32 rx_fib_index0;
           u32 proto0;
           snat_session_t * s0 = 0;
@@ -503,14 +658,27 @@ snat_out2in_node_fn (vlib_main_t * vm,
           kv0.key = key0.as_u64;
 
           if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
-            goto trace00;
+            {
+              /* Try to match static mapping by external address and port,
+                 destination address and port in packet */
+              if (snat_static_mapping_match(sm, key0, &sm0, 1))
+                {
+                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  goto trace00;
+                }
+
+              /* Create session initiated by host from external network */
+              s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node);
+              if (!s0)
+                goto trace00;
+            }
           else
             s0 = pool_elt_at_index (sm->sessions, value0.value);
 
           old_addr0 = ip0->dst_address.as_u32;
           ip0->dst_address = s0->in2out.addr;
           new_addr0 = ip0->dst_address.as_u32;
-          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
 
           sum0 = ip0->checksum;
           sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
@@ -541,13 +709,17 @@ snat_out2in_node_fn (vlib_main_t * vm,
               udp0->checksum = 0;
             }
 
-          /* Accounting, per-user LRU list maintenance */
+          /* Accounting */
           s0->last_heard = now;
           s0->total_pkts++;
           s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
-          clib_dlist_remove (sm->list_pool, s0->per_user_index);
-          clib_dlist_addtail (sm->list_pool, s0->per_user_list_head_index,
-                              s0->per_user_index);
+          /* Per-user LRU list maintenance for dynamic translation */
+          if (!snat_is_session_static (s0))
+            {
+              clib_dlist_remove (sm->list_pool, s0->per_user_index);
+              clib_dlist_addtail (sm->list_pool, s0->per_user_list_head_index,
+                                  s0->per_user_index);
+            }
         trace00:
 
           if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
@@ -599,3 +771,257 @@ VLIB_REGISTER_NODE (snat_out2in_node) = {
   },
 };
 VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_node, snat_out2in_node_fn);
+
+static inline u32 icmp_out2in_fast (snat_main_t *sm,
+                                    vlib_buffer_t * b0,
+                                    ip4_header_t * ip0,
+                                    icmp46_header_t * icmp0,
+                                    u32 sw_if_index0,
+                                    vlib_node_runtime_t * node,
+                                    u32 next0)
+{
+  snat_session_key_t key0, sm0;
+  icmp_echo_header_t *echo0;
+  u32 new_addr0, old_addr0;
+  u16 old_id0, new_id0;
+  ip_csum_t sum0;
+  snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+
+  echo0 = (icmp_echo_header_t *)(icmp0+1);
+
+  key0.addr = ip0->dst_address;
+  key0.port = echo0->identifier;
+
+  if (snat_static_mapping_match(sm, key0, &sm0, 1))
+    {
+      ip4_address_t * first_int_addr;
+
+      if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
+        {
+          first_int_addr =
+            ip4_interface_first_address (sm->ip4_main, sw_if_index0,
+                                         0 /* just want the address */);
+          rt->cached_sw_if_index = sw_if_index0;
+          rt->cached_ip4_address = first_int_addr->as_u32;
+        }
+
+      /* Don't NAT packet aimed at the intfc address */
+      if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
+                        rt->cached_ip4_address))
+        return next0;
+
+      b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+      return SNAT_OUT2IN_NEXT_DROP;
+    }
+
+  new_addr0 = sm0.addr.as_u32;
+  new_id0 = sm0.port;
+  vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+
+  old_addr0 = ip0->dst_address.as_u32;
+  ip0->dst_address.as_u32 = new_addr0;
+
+  sum0 = ip0->checksum;
+  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                         ip4_header_t,
+                         dst_address /* changed member */);
+  ip0->checksum = ip_csum_fold (sum0);
+
+  if (PREDICT_FALSE(new_id0 != echo0->identifier))
+    {
+      old_id0 = echo0->identifier;
+      echo0->identifier = new_id0;
+
+      sum0 = icmp0->checksum;
+      sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                             identifier);
+      icmp0->checksum = ip_csum_fold (sum0);
+    }
+
+  return next0;
+}
+
+static uword
+snat_out2in_fast_node_fn (vlib_main_t * vm,
+	        	  vlib_node_runtime_t * node,
+		          vlib_frame_t * frame)
+{
+  u32 n_left_from, * from, * to_next;
+  snat_out2in_next_t next_index;
+  u32 pkts_processed = 0;
+  snat_main_t * sm = &snat_main;
+  ip_lookup_main_t * lm = sm->ip4_lookup_main;
+  ip_config_main_t * cm = &lm->feature_config_mains[VNET_IP_RX_UNICAST_FEAT];
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index,
+			   to_next, n_left_to_next);
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+          u32 bi0;
+	  vlib_buffer_t * b0;
+          u32 next0 = SNAT_OUT2IN_NEXT_DROP;
+          u32 sw_if_index0;
+          ip4_header_t * ip0;
+          ip_csum_t sum0;
+          u32 new_addr0, old_addr0;
+          u16 new_port0, old_port0;
+          udp_header_t * udp0;
+          tcp_header_t * tcp0;
+          icmp46_header_t * icmp0;
+          snat_session_key_t key0, sm0;
+          u32 proto0;
+
+          /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+
+	  vnet_get_config_data (&cm->config_main,
+                                &b0->current_config_index,
+                                &next0,
+                                0 /* sizeof config data */);
+          proto0 = ~0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_UDP)
+            ? SNAT_PROTOCOL_UDP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_TCP)
+            ? SNAT_PROTOCOL_TCP : proto0;
+          proto0 = (ip0->protocol == IP_PROTOCOL_ICMP)
+            ? SNAT_PROTOCOL_ICMP : proto0;
+
+          if (PREDICT_FALSE (proto0 == ~0))
+              goto trace00;
+
+          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+            {
+              next0 = icmp_out2in_fast
+                (sm, b0, ip0, icmp0, sw_if_index0, node, next0);
+              goto trace00;
+            }
+
+          key0.addr = ip0->dst_address;
+          key0.port = udp0->dst_port;
+
+          if (snat_static_mapping_match(sm, key0, &sm0, 1))
+            {
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace00;
+            }
+
+          new_addr0 = sm0.addr.as_u32;
+          new_port0 = sm0.port;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+          old_addr0 = ip0->dst_address.as_u32;
+          ip0->dst_address.as_u32 = new_addr0;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_FALSE(new_port0 != udp0->dst_port))
+            {
+               if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+                {
+                  old_port0 = tcp0->ports.dst;
+                  tcp0->ports.dst = new_port0;
+
+                  sum0 = tcp0->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 */);
+                  tcp0->checksum = ip_csum_fold(sum0);
+                }
+              else
+                {
+                  old_port0 = udp0->dst_port;
+                  udp0->dst_port = new_port0;
+                  udp0->checksum = 0;
+                }
+            }
+          else
+            {
+              if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+                {
+                  sum0 = tcp0->checksum;
+                  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                         ip4_header_t,
+                                         dst_address /* changed member */);
+
+                  tcp0->checksum = ip_csum_fold(sum0);
+                }
+            }
+
+        trace00:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+            {
+              snat_out2in_trace_t *t =
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+            }
+
+          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
+
+          /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, snat_out2in_fast_node.index,
+                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
+                               pkts_processed);
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (snat_out2in_fast_node) = {
+  .function = snat_out2in_fast_node_fn,
+  .name = "snat-out2in-fast",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_out2in_fast_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  
+  .n_errors = ARRAY_LEN(snat_out2in_error_strings),
+  .error_strings = snat_out2in_error_strings,
+
+  .runtime_data_bytes = sizeof (snat_runtime_t),
+  
+  .n_next_nodes = SNAT_OUT2IN_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
+  },
+};
+VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_fast_node, snat_out2in_fast_node_fn);