CGN: fix outside port calculation and set buffer error (VPP-623)
[vpp.git] / src / plugins / snat / out2in.c
index 9e5a8af..178aa56 100644 (file)
 #include <vnet/handoff.h>
 
 #include <vnet/ip/ip.h>
+#include <vnet/udp/udp.h>
 #include <vnet/ethernet/ethernet.h>
 #include <vnet/fib/ip4_fib.h>
 #include <snat/snat.h>
+#include <snat/snat_ipfix_logging.h>
+#include <snat/snat_det.h>
 
 #include <vppinfra/hash.h>
 #include <vppinfra/error.h>
@@ -78,6 +81,7 @@ static u8 * format_snat_out2in_worker_handoff_trace (u8 * s, va_list * args)
 vlib_node_registration_t snat_out2in_node;
 vlib_node_registration_t snat_out2in_fast_node;
 vlib_node_registration_t snat_out2in_worker_handoff_node;
+vlib_node_registration_t snat_det_out2in_node;
 
 #define foreach_snat_out2in_error                       \
 _(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
@@ -101,6 +105,7 @@ static char * snat_out2in_error_strings[] = {
 typedef enum {
   SNAT_OUT2IN_NEXT_DROP,
   SNAT_OUT2IN_NEXT_LOOKUP,
+  SNAT_OUT2IN_NEXT_ICMP_ERROR,
   SNAT_OUT2IN_N_NEXT,
 } snat_out2in_next_t;
 
@@ -144,6 +149,7 @@ create_session_for_static_mapping (snat_main_t *sm,
       pool_get (sm->per_thread_data[cpu_index].users, u);
       memset (u, 0, sizeof (*u));
       u->addr = in2out.addr;
+      u->fib_index = in2out.fib_index;
 
       pool_get (sm->per_thread_data[cpu_index].list_pool,
                 per_user_list_head_elt);
@@ -210,9 +216,20 @@ create_session_for_static_mapping (snat_main_t *sm,
   if (clib_bihash_add_del_8_8 (&sm->out2in, &kv0, 1 /* is_add */))
       clib_warning ("out2in key add failed");
 
-  return s;
+  /* log NAT event */
+  snat_ipfix_logging_nat44_ses_create(s->in2out.addr.as_u32,
+                                      s->out2in.addr.as_u32,
+                                      s->in2out.protocol,
+                                      s->in2out.port,
+                                      s->out2in.port,
+                                      s->in2out.fib_index);
+   return s;
 }
 
+typedef struct {
+  u16 src_port, dst_port;
+} tcp_udp_header_t;
+
 static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
                                          vlib_buffer_t * b0,
                                          ip4_header_t * ip0,
@@ -221,24 +238,67 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
                                          u32 rx_fib_index0,
                                          vlib_node_runtime_t * node,
                                          u32 next0, f64 now,
-                                         u32 cpu_index)
+                                         u32 cpu_index,
+                                         snat_session_t ** p_s0)
 {
   snat_session_key_t key0, sm0;
-  icmp_echo_header_t *echo0;
+  icmp_echo_header_t *echo0, *inner_echo0 = 0;
+  ip4_header_t *inner_ip0 = 0;
+  void *l4_header = 0;
+  icmp46_header_t *inner_icmp0;
   clib_bihash_kv_8_8_t kv0, value0;
-  snat_session_t * s0;
+  snat_session_t * s0 = 0;
   u32 new_addr0, old_addr0;
   u16 old_id0, new_id0;
   ip_csum_t sum0;
+  u16 checksum0;
   snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data;
+  u8 is_error_message = 0;
 
   echo0 = (icmp_echo_header_t *)(icmp0+1);
 
   key0.addr = ip0->dst_address;
-  key0.port = echo0->identifier;
-  key0.protocol = SNAT_PROTOCOL_ICMP;
   key0.fib_index = rx_fib_index0;
-  
+
+  switch(icmp0->type)
+    {
+    case ICMP4_destination_unreachable:
+    case ICMP4_time_exceeded:
+    case ICMP4_parameter_problem:
+    case ICMP4_source_quench:
+    case ICMP4_redirect:
+    case ICMP4_alternate_host_address:
+      is_error_message = 1;
+    }
+
+  if (!is_error_message)
+    {
+      key0.protocol = SNAT_PROTOCOL_ICMP;
+      key0.port = echo0->identifier;
+    }
+  else
+    {
+      inner_ip0 = (ip4_header_t *)(echo0+1);
+      l4_header = ip4_next_header (inner_ip0);
+      key0.protocol = ip_proto_to_snat_proto (inner_ip0->protocol);
+      switch (key0.protocol)
+        {
+        case SNAT_PROTOCOL_ICMP:
+          inner_icmp0 = (icmp46_header_t*)l4_header;
+          inner_echo0 = (icmp_echo_header_t *)(inner_icmp0+1);
+          key0.port = inner_echo0->identifier;
+          break;
+        case SNAT_PROTOCOL_UDP:
+        case SNAT_PROTOCOL_TCP:
+          key0.port = ((tcp_udp_header_t*)l4_header)->src_port;
+          break;
+        default:
+          b0->error = node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
+          next0 = SNAT_OUT2IN_NEXT_DROP;
+          goto out;
+        }
+    }
+
   kv0.key = key0.as_u64;
   
   if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
@@ -255,47 +315,122 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
                 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;
+              if (first_int_addr)
+                rt->cached_ip4_address = first_int_addr->as_u32;
+              else
+                rt->cached_ip4_address = 0;
             }
           
           /* Don't NAT packet aimed at the intfc address */
-          if (PREDICT_FALSE(ip0->dst_address.as_u32 ==
-                            rt->cached_ip4_address))
-            return next0;
+          if (PREDICT_FALSE(ip0->dst_address.as_u32 == rt->cached_ip4_address))
+            goto out;
 
           b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-          return SNAT_OUT2IN_NEXT_DROP;
+          next0 = SNAT_OUT2IN_NEXT_DROP;
+          goto out;
+        }
+
+      if (is_error_message)
+        {
+          next0 = SNAT_OUT2IN_NEXT_DROP;
+          goto out;
         }
 
       /* Create session initiated by host from external network */
       s0 = create_session_for_static_mapping(sm, b0, sm0, key0,
                                              node, cpu_index);
+
       if (!s0)
-        return SNAT_OUT2IN_NEXT_DROP;
+        {
+          next0 = SNAT_OUT2IN_NEXT_DROP;
+          goto out;
+        }
     }
   else
     s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
                             value0.value);
 
+  if (PREDICT_FALSE(icmp0->type != ICMP4_echo_reply && !is_error_message))
+    {
+      b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
+      next0 = SNAT_OUT2IN_NEXT_DROP;
+      goto out;
+    }
+
+  sum0 = ip_incremental_checksum (0, icmp0,
+                                  ntohs(ip0->length) - ip4_header_bytes (ip0));
+  checksum0 = ~ip_csum_fold (sum0);
+  if (checksum0 != 0 && checksum0 != 0xffff)
+    {
+      next0 = SNAT_OUT2IN_NEXT_DROP;
+      goto out;
+    }
+
   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->in2out.fib_index;
   
   sum0 = ip0->checksum;
-  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
-                         ip4_header_t,
+  sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                          dst_address /* changed member */);
   ip0->checksum = ip_csum_fold (sum0);
   
-  old_id0 = echo0->identifier;
-  new_id0 = s0->in2out.port;
-  echo0->identifier = new_id0;
+  if (!is_error_message)
+    {
+      old_id0 = echo0->identifier;
+      new_id0 = s0->in2out.port;
+      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);
+      sum0 = icmp0->checksum;
+      sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                             identifier /* changed member */);
+      icmp0->checksum = ip_csum_fold (sum0);
+    }
+  else
+    {
+      if (!ip4_header_checksum_is_valid (inner_ip0))
+        {
+          next0 = SNAT_OUT2IN_NEXT_DROP;
+          goto out;
+        }
+
+      old_addr0 = inner_ip0->src_address.as_u32;
+      inner_ip0->src_address = s0->in2out.addr;
+      new_addr0 = inner_ip0->src_address.as_u32;
+
+      sum0 = icmp0->checksum;
+      sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
+                             src_address /* changed member */);
+      icmp0->checksum = ip_csum_fold (sum0);
+
+      switch (key0.protocol)
+        {
+        case SNAT_PROTOCOL_ICMP:
+          old_id0 = inner_echo0->identifier;
+          new_id0 = s0->in2out.port;
+          inner_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);
+          break;
+        case SNAT_PROTOCOL_UDP:
+        case SNAT_PROTOCOL_TCP:
+          old_id0 = ((tcp_udp_header_t*)l4_header)->src_port;
+          new_id0 = s0->in2out.port;
+          ((tcp_udp_header_t*)l4_header)->src_port = new_id0;
+
+          sum0 = icmp0->checksum;
+          sum0 = ip_csum_update (sum0, old_id0, new_id0, tcp_udp_header_t,
+                                 src_port);
+          icmp0->checksum = ip_csum_fold (sum0);
+          break;
+        default:
+          ASSERT(0);
+        }
+    }
 
   /* Accounting */
   s0->last_heard = now;
@@ -311,6 +446,8 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
                           s0->per_user_index);
     }
 
+out:
+  *p_s0 = s0;
   return next0;
 }
 
@@ -393,22 +530,26 @@ snat_out2in_node_fn (vlib_main_t * vm,
          rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
                                    sw_if_index0);
 
-          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;
+          proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
           if (PREDICT_FALSE (proto0 == ~0))
               goto trace0;
 
+          if (PREDICT_FALSE(ip0->ttl == 1))
+            {
+              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
+                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
+                                           0);
+              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
+              goto trace0;
+            }
+
           if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
             {
               next0 = icmp_out2in_slow_path 
                 (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node, 
-                 next0, now, cpu_index);
+                 next0, now, cpu_index, &s0);
               goto trace0;
             }
 
@@ -426,6 +567,14 @@ snat_out2in_node_fn (vlib_main_t * vm,
               if (snat_static_mapping_match(sm, key0, &sm0, 1))
                 {
                   b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  /* 
+                   * Send DHCP packets to the ipv4 stack, or we won't
+                   * be able to use dhcp client on the outside interface
+                   */
+                  if (proto0 != SNAT_PROTOCOL_UDP 
+                      || (udp0->dst_port 
+                          != clib_host_to_net_u16(UDP_DST_PORT_dhcp_to_client)))
+                    next0 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace0;
                 }
 
@@ -433,7 +582,11 @@ snat_out2in_node_fn (vlib_main_t * vm,
               s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node,
                                                      cpu_index);
               if (!s0)
-                goto trace0;
+                {
+                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  next0 = SNAT_OUT2IN_NEXT_DROP;
+                  goto trace0;
+                }
             }
           else
             s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
@@ -452,9 +605,9 @@ snat_out2in_node_fn (vlib_main_t * vm,
 
           if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
             {
-              old_port0 = tcp0->ports.dst;
-              tcp0->ports.dst = s0->in2out.port;
-              new_port0 = tcp0->ports.dst;
+              old_port0 = tcp0->dst_port;
+              tcp0->dst_port = s0->in2out.port;
+              new_port0 = tcp0->dst_port;
 
               sum0 = tcp0->checksum;
               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
@@ -512,22 +665,26 @@ snat_out2in_node_fn (vlib_main_t * vm,
          rx_fib_index1 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
                                    sw_if_index1);
 
-          proto1 = ~0;
-          proto1 = (ip1->protocol == IP_PROTOCOL_UDP) 
-            ? SNAT_PROTOCOL_UDP : proto1;
-          proto1 = (ip1->protocol == IP_PROTOCOL_TCP) 
-            ? SNAT_PROTOCOL_TCP : proto1;
-          proto1 = (ip1->protocol == IP_PROTOCOL_ICMP) 
-            ? SNAT_PROTOCOL_ICMP : proto1;
+          proto1 = ip_proto_to_snat_proto (ip1->protocol);
 
           if (PREDICT_FALSE (proto1 == ~0))
               goto trace1;
 
+          if (PREDICT_FALSE(ip0->ttl == 1))
+            {
+              vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+              icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
+                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
+                                           0);
+              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
+              goto trace1;
+            }
+
           if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
             {
               next1 = icmp_out2in_slow_path 
                 (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node, 
-                 next1, now, cpu_index);
+                 next1, now, cpu_index, &s1);
               goto trace1;
             }
 
@@ -545,6 +702,14 @@ snat_out2in_node_fn (vlib_main_t * vm,
               if (snat_static_mapping_match(sm, key1, &sm1, 1))
                 {
                   b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  /* 
+                   * Send DHCP packets to the ipv4 stack, or we won't
+                   * be able to use dhcp client on the outside interface
+                   */
+                  if (proto1 != SNAT_PROTOCOL_UDP 
+                      || (udp1->dst_port 
+                          != clib_host_to_net_u16(UDP_DST_PORT_dhcp_to_client)))
+                    next1 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace1;
                 }
 
@@ -552,7 +717,11 @@ snat_out2in_node_fn (vlib_main_t * vm,
               s1 = create_session_for_static_mapping(sm, b1, sm1, key1, node,
                                                      cpu_index);
               if (!s1)
-                goto trace1;
+                {
+                  b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  next1 = SNAT_OUT2IN_NEXT_DROP;
+                  goto trace1;
+                }
             }
           else
             s1 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
@@ -571,9 +740,9 @@ snat_out2in_node_fn (vlib_main_t * vm,
 
           if (PREDICT_TRUE(proto1 == SNAT_PROTOCOL_TCP))
             {
-              old_port1 = tcp1->ports.dst;
-              tcp1->ports.dst = s1->in2out.port;
-              new_port1 = tcp1->ports.dst;
+              old_port1 = tcp1->dst_port;
+              tcp1->dst_port = s1->in2out.port;
+              new_port1 = tcp1->dst_port;
 
               sum1 = tcp1->checksum;
               sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
@@ -665,22 +834,26 @@ snat_out2in_node_fn (vlib_main_t * vm,
          rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index, 
                                    sw_if_index0);
 
-          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;
+          proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
           if (PREDICT_FALSE (proto0 == ~0))
               goto trace00;
 
+          if (PREDICT_FALSE(ip0->ttl == 1))
+            {
+              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
+                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
+                                           0);
+              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
+              goto trace00;
+            }
+
           if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
             {
               next0 = icmp_out2in_slow_path 
                 (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node, 
-                 next0, now, cpu_index);
+                 next0, now, cpu_index, &s0);
               goto trace00;
             }
 
@@ -698,6 +871,15 @@ snat_out2in_node_fn (vlib_main_t * vm,
               if (snat_static_mapping_match(sm, key0, &sm0, 1))
                 {
                   b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                  /* 
+                   * Send DHCP packets to the ipv4 stack, or we won't
+                   * be able to use dhcp client on the outside interface
+                   */
+                  if (proto0 != SNAT_PROTOCOL_UDP 
+                      || (udp0->dst_port 
+                          != clib_host_to_net_u16(UDP_DST_PORT_dhcp_to_client)))
+
+                    next0 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace00;
                 }
 
@@ -705,7 +887,11 @@ snat_out2in_node_fn (vlib_main_t * vm,
               s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node,
                                                      cpu_index);
               if (!s0)
-                goto trace00;
+                {
+                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                    next0 = SNAT_OUT2IN_NEXT_DROP;
+                  goto trace00;
+                }
             }
           else
             s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions,
@@ -724,9 +910,9 @@ snat_out2in_node_fn (vlib_main_t * vm,
 
           if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
             {
-              old_port0 = tcp0->ports.dst;
-              tcp0->ports.dst = s0->in2out.port;
-              new_port0 = tcp0->ports.dst;
+              old_port0 = tcp0->dst_port;
+              tcp0->dst_port = s0->in2out.port;
+              new_port0 = tcp0->dst_port;
 
               sum0 = tcp0->checksum;
               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
@@ -807,10 +993,432 @@ VLIB_REGISTER_NODE (snat_out2in_node) = {
   .next_nodes = {
     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
+    [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
   },
 };
 VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_node, snat_out2in_node_fn);
 
+/**************************/
+/*** deterministic mode ***/
+/**************************/
+static uword
+snat_det_out2in_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;
+
+  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 >= 4 && n_left_to_next >= 2)
+        {
+          u32 bi0, bi1;
+         vlib_buffer_t * b0, * b1;
+          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
+          u32 next1 = SNAT_OUT2IN_NEXT_LOOKUP;
+          u32 sw_if_index0, sw_if_index1;
+          ip4_header_t * ip0, * ip1;
+          ip_csum_t sum0, sum1;
+          ip4_address_t new_addr0, old_addr0, new_addr1, old_addr1;
+          u16 new_port0, old_port0, old_port1, new_port1;
+          udp_header_t * udp0, * udp1;
+          tcp_header_t * tcp0, * tcp1;
+          u32 proto0, proto1;
+          snat_det_out_key_t key0, key1;
+          snat_det_map_t * dm0, * dm1;
+          snat_det_session_t * ses0 = 0, * ses1 = 0;
+
+         /* Prefetch next iteration. */
+         {
+           vlib_buffer_t * p2, * p3;
+
+           p2 = vlib_get_buffer (vm, from[2]);
+           p3 = vlib_get_buffer (vm, from[3]);
+
+           vlib_prefetch_buffer_header (p2, LOAD);
+           vlib_prefetch_buffer_header (p3, LOAD);
+
+           CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
+           CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
+         }
+
+          /* speculatively enqueue b0 and b1 to the current next frame */
+         to_next[0] = bi0 = from[0];
+         to_next[1] = bi1 = from[1];
+         from += 2;
+         to_next += 2;
+         n_left_from -= 2;
+         n_left_to_next -= 2;
+
+         b0 = vlib_get_buffer (vm, bi0);
+         b1 = vlib_get_buffer (vm, bi1);
+
+          ip0 = vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+
+          key0.ext_host_addr = ip0->src_address;
+          key0.ext_host_port = tcp0->src;
+          key0.out_port = tcp0->dst;
+
+          dm0 = snat_det_map_by_out(sm, &ip0->dst_address);
+          if (PREDICT_FALSE(!dm0))
+            {
+              clib_warning("unknown dst address:  %U",
+                           format_ip4_address, &ip0->dst_address);
+              next0 = SNAT_OUT2IN_NEXT_DROP;
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace0;
+            }
+
+          snat_det_reverse(dm0, &ip0->dst_address,
+                           clib_net_to_host_u16(tcp0->dst), &new_addr0);
+
+          ses0 = snat_det_get_ses_by_out (dm0, &new_addr0, key0.as_u64);
+          if (PREDICT_FALSE(!ses0))
+            {
+              clib_warning("no match src %U:%d dst %U:%d for user %U",
+                           format_ip4_address, &ip0->src_address,
+                           clib_net_to_host_u16 (tcp0->src),
+                           format_ip4_address, &ip0->dst_address,
+                           clib_net_to_host_u16 (tcp0->dst),
+                           format_ip4_address, &new_addr0);
+              next0 = SNAT_OUT2IN_NEXT_DROP;
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace0;
+            }
+          new_port0 = ses0->in_port;
+
+          proto0 = ip_proto_to_snat_proto (ip0->protocol);
+
+          old_addr0 = ip0->dst_address;
+          ip0->dst_address = new_addr0;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm->inside_fib_index;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+            {
+              if (tcp0->flags & TCP_FLAG_FIN && ses0->state == SNAT_SESSION_TCP_ESTABLISHED)
+                ses0->state = SNAT_SESSION_TCP_CLOSE_WAIT;
+              else if (tcp0->flags & TCP_FLAG_ACK && 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
+            {
+              old_port0 = udp0->dst_port;
+              udp0->dst_port = new_port0;
+              udp0->checksum = 0;
+            }
+
+        trace0:
+
+          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;
+              t->session_index = ~0;
+              if (ses0)
+                t->session_index = ses0 - dm0->sessions;
+            }
+
+          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
+
+         b1 = vlib_get_buffer (vm, bi1);
+
+          ip1 = vlib_buffer_get_current (b1);
+          udp1 = ip4_next_header (ip1);
+          tcp1 = (tcp_header_t *) udp1;
+
+          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_RX];
+
+          key1.ext_host_addr = ip1->src_address;
+          key1.ext_host_port = tcp1->src;
+          key1.out_port = tcp1->dst;
+
+          dm1 = snat_det_map_by_out(sm, &ip1->dst_address);
+          if (PREDICT_FALSE(!dm1))
+            {
+              clib_warning("unknown dst address:  %U",
+                           format_ip4_address, &ip1->dst_address);
+              next1 = SNAT_OUT2IN_NEXT_DROP;
+              b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace1;
+            }
+
+          snat_det_reverse(dm1, &ip1->dst_address,
+                           clib_net_to_host_u16(tcp1->dst), &new_addr1);
+
+          ses1 = snat_det_get_ses_by_out (dm1, &new_addr1, key1.as_u64);
+          if (PREDICT_FALSE(!ses1))
+            {
+              clib_warning("no match src %U:%d dst %U:%d for user %U",
+                           format_ip4_address, &ip1->src_address,
+                           clib_net_to_host_u16 (tcp1->src),
+                           format_ip4_address, &ip1->dst_address,
+                           clib_net_to_host_u16 (tcp1->dst),
+                           format_ip4_address, &new_addr1);
+              next1 = SNAT_OUT2IN_NEXT_DROP;
+              b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace1;
+            }
+          new_port1 = ses1->in_port;
+
+          proto1 = ip_proto_to_snat_proto (ip1->protocol);
+
+          old_addr1 = ip1->dst_address;
+          ip1->dst_address = new_addr1;
+          vnet_buffer(b1)->sw_if_index[VLIB_TX] = sm->inside_fib_index;
+
+          sum1 = ip1->checksum;
+          sum1 = ip_csum_update (sum1, old_addr1.as_u32, new_addr1.as_u32,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip1->checksum = ip_csum_fold (sum1);
+
+          if (PREDICT_TRUE(proto1 == SNAT_PROTOCOL_TCP))
+            {
+              if (tcp1->flags & TCP_FLAG_FIN && ses1->state == SNAT_SESSION_TCP_ESTABLISHED)
+                ses1->state = SNAT_SESSION_TCP_CLOSE_WAIT;
+              else if (tcp1->flags & TCP_FLAG_ACK && 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
+            {
+              old_port1 = udp1->dst_port;
+              udp1->dst_port = new_port1;
+              udp1->checksum = 0;
+            }
+
+        trace1:
+
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b1->flags & VLIB_BUFFER_IS_TRACED)))
+            {
+              snat_out2in_trace_t *t =
+                 vlib_add_trace (vm, node, b1, sizeof (*t));
+              t->sw_if_index = sw_if_index1;
+              t->next_index = next1;
+              t->session_index = ~0;
+              if (ses1)
+                t->session_index = ses1 - dm1->sessions;
+            }
+
+          pkts_processed += next1 != SNAT_OUT2IN_NEXT_DROP;
+
+          /* verify speculative enqueues, maybe switch current next frame */
+          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
+                                           to_next, n_left_to_next,
+                                           bi0, bi1, next0, next1);
+         }
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+       {
+          u32 bi0;
+         vlib_buffer_t * b0;
+          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
+          u32 sw_if_index0;
+          ip4_header_t * ip0;
+          ip_csum_t sum0;
+          ip4_address_t new_addr0, old_addr0;
+          u16 new_port0, old_port0;
+          udp_header_t * udp0;
+          tcp_header_t * tcp0;
+          u32 proto0;
+          snat_det_out_key_t key0;
+          snat_det_map_t * dm0;
+          snat_det_session_t * ses0 = 0;
+
+          /* 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;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+
+          key0.ext_host_addr = ip0->src_address;
+          key0.ext_host_port = tcp0->src;
+          key0.out_port = tcp0->dst;
+
+          dm0 = snat_det_map_by_out(sm, &ip0->dst_address);
+          if (PREDICT_FALSE(!dm0))
+            {
+              clib_warning("unknown dst address:  %U",
+                           format_ip4_address, &ip0->dst_address);
+              next0 = SNAT_OUT2IN_NEXT_DROP;
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace00;
+            }
+
+          snat_det_reverse(dm0, &ip0->dst_address,
+                           clib_net_to_host_u16(tcp0->dst), &new_addr0);
+
+          ses0 = snat_det_get_ses_by_out (dm0, &new_addr0, key0.as_u64);
+          if (PREDICT_FALSE(!ses0))
+            {
+              clib_warning("no match src %U:%d dst %U:%d for user %U",
+                           format_ip4_address, &ip0->src_address,
+                           clib_net_to_host_u16 (tcp0->src),
+                           format_ip4_address, &ip0->dst_address,
+                           clib_net_to_host_u16 (tcp0->dst),
+                           format_ip4_address, &new_addr0);
+              next0 = SNAT_OUT2IN_NEXT_DROP;
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+              goto trace00;
+            }
+          new_port0 = ses0->in_port;
+
+          proto0 = ip_proto_to_snat_proto (ip0->protocol);
+
+          old_addr0 = ip0->dst_address;
+          ip0->dst_address = new_addr0;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm->inside_fib_index;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+            {
+              if (tcp0->flags & TCP_FLAG_FIN && ses0->state == SNAT_SESSION_TCP_ESTABLISHED)
+                ses0->state = SNAT_SESSION_TCP_CLOSE_WAIT;
+              else if (tcp0->flags & TCP_FLAG_ACK && 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
+            {
+              old_port0 = udp0->dst_port;
+              udp0->dst_port = new_port0;
+              udp0->checksum = 0;
+            }
+
+        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;
+              t->session_index = ~0;
+              if (ses0)
+                t->session_index = ses0 - dm0->sessions;
+            }
+
+          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_det_out2in_node.index,
+                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
+                               pkts_processed);
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (snat_det_out2in_node) = {
+  .function = snat_det_out2in_node_fn,
+  .name = "snat-det-out2in",
+  .vector_size = sizeof (u32),
+  .format_trace = format_snat_out2in_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 = 2,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
+    [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
+  },
+};
+VLIB_NODE_FUNCTION_MULTIARCH (snat_det_out2in_node, snat_det_out2in_node_fn);
+
+/**********************/
+/*** worker handoff ***/
+/**********************/
 static uword
 snat_out2in_worker_handoff_fn (vlib_main_t * vm,
                                vlib_node_runtime_t * node,
@@ -851,9 +1459,6 @@ snat_out2in_worker_handoff_fn (vlib_main_t * vm,
       u32 sw_if_index0;
       u32 rx_fib_index0;
       ip4_header_t * ip0;
-      udp_header_t * udp0;
-      snat_static_mapping_key_t key0;
-      clib_bihash_kv_8_8_t kv0, value0;
       u8 do_handoff;
 
       bi0 = from[0];
@@ -866,45 +1471,8 @@ snat_out2in_worker_handoff_fn (vlib_main_t * vm,
       rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
 
       ip0 = vlib_buffer_get_current (b0);
-      udp0 = ip4_next_header (ip0);
 
-      key0.addr = ip0->dst_address;
-      key0.port = udp0->dst_port;
-      key0.fib_index = rx_fib_index0;
-
-      if (PREDICT_FALSE(ip0->protocol == IP_PROTOCOL_ICMP))
-        {
-          icmp46_header_t * icmp0 = (icmp46_header_t *) udp0;
-          icmp_echo_header_t *echo0 = (icmp_echo_header_t *)(icmp0+1);
-          key0.port = echo0->identifier;
-        }
-
-      kv0.key = key0.as_u64;
-
-      /* Ever heard of of the "user" before? */
-      if (clib_bihash_search_8_8 (&sm->worker_by_out, &kv0, &value0))
-        {
-          key0.port = 0;
-          kv0.key = key0.as_u64;
-
-          if (clib_bihash_search_8_8 (&sm->worker_by_out, &kv0, &value0))
-            {
-              /* No, assign next available worker (RR) */
-              next_worker_index = sm->first_worker_index +
-                sm->workers[sm->next_worker++ % vec_len (sm->workers)];
-            }
-          else
-            {
-              /* Static mapping without port */
-              next_worker_index = value0.value;
-            }
-
-          /* Add to translated packets worker lookup */
-          kv0.value = next_worker_index;
-          clib_bihash_add_del_8_8 (&sm->worker_by_out, &kv0, 1);
-        }
-      else
-        next_worker_index = value0.value;
+      next_worker_index = sm->worker_out2in_cb(ip0, rx_fib_index0);
 
       if (PREDICT_FALSE (next_worker_index != cpu_index))
         {
@@ -944,7 +1512,7 @@ snat_out2in_worker_handoff_fn (vlib_main_t * vm,
           /* if this is 1st frame */
           if (!f)
             {
-              f = vlib_get_frame_to_node (vm, snat_out2in_node.index);
+              f = vlib_get_frame_to_node (vm, sm->out2in_node_index);
               to_next = vlib_frame_vector_args (f);
             }
 
@@ -964,7 +1532,7 @@ snat_out2in_worker_handoff_fn (vlib_main_t * vm,
     }
 
   if (f)
-    vlib_put_frame_to_node (vm, snat_out2in_node.index, f);
+    vlib_put_frame_to_node (vm, sm->out2in_node_index, f);
 
   if (hf)
     hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;
@@ -1011,6 +1579,9 @@ VLIB_REGISTER_NODE (snat_out2in_worker_handoff_node) = {
 
 VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_worker_handoff_node, snat_out2in_worker_handoff_fn);
 
+/********************************/
+/*** static mapping only mode ***/
+/********************************/
 static inline u32 icmp_out2in_fast (snat_main_t *sm,
                                     vlib_buffer_t * b0,
                                     ip4_header_t * ip0,
@@ -1043,7 +1614,10 @@ static inline u32 icmp_out2in_fast (snat_main_t *sm,
             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;
+          if (first_int_addr)
+            rt->cached_ip4_address = first_int_addr->as_u32;
+          else
+            rt->cached_ip4_address = 0;
         }
 
       /* Don't NAT packet aimed at the intfc address */
@@ -1140,13 +1714,7 @@ snat_out2in_fast_node_fn (vlib_main_t * vm,
 
          vnet_feature_next (sw_if_index0, &next0, b0);
 
-          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;
+          proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
           if (PREDICT_FALSE (proto0 == ~0))
               goto trace00;
@@ -1184,8 +1752,8 @@ snat_out2in_fast_node_fn (vlib_main_t * vm,
             {
                if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
                 {
-                  old_port0 = tcp0->ports.dst;
-                  tcp0->ports.dst = new_port0;
+                  old_port0 = tcp0->dst_port;
+                  tcp0->dst_port = new_port0;
 
                   sum0 = tcp0->checksum;
                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
@@ -1263,6 +1831,7 @@ VLIB_REGISTER_NODE (snat_out2in_fast_node) = {
   .next_nodes = {
     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
+    [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
   },
 };
 VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_fast_node, snat_out2in_fast_node_fn);