nat: Final NAT44 EI/ED split patch

This patch achieves complete separation of
endpoint-dependent and endpoint-independent IPv4 NAT
features. Some common stuff is also moved to NAT
library.

Type: refactor

Change-Id: I52468b7e2b5ac28958a2baf8e2ea01787322e801
Signed-off-by: Filip Varga <fivarga@cisco.com>

1 files changed, 748 insertions, 0 deletions

diff --git a/src/plugins/nat/nat44-ei/nat44_ei_hairpinning.c b/src/plugins/nat/nat44-ei/nat44_ei_hairpinning.c
new file mode 100644
index 00000000000..0de2de1faf4
--- /dev/null
+++ b/src/plugins/nat/nat44-ei/nat44_ei_hairpinning.c
@@ -0,0 +1,748 @@
+/*
+ * nat44_ei.c - nat44 endpoint dependent plugin
+ * * Copyright (c) 2020 Cisco and/or its affiliates.  * Licensed under the
+ * Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License
+ * at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/fib/ip4_fib.h>
+
+#include <nat/nat44-ei/nat44_ei.h>
+#include <nat/nat44-ei/nat44_ei_inlines.h>
+#include <nat/nat44-ei/nat44_ei_hairpinning.h>
+
+/* NAT buffer flags */
+#define NAT44_EI_FLAG_HAIRPINNING (1 << 0)
+
+typedef enum
+{
+  NAT44_EI_HAIRPIN_SRC_NEXT_DROP,
+  NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT,
+  NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT_WH,
+  NAT44_EI_HAIRPIN_SRC_NEXT_INTERFACE_OUTPUT,
+  NAT44_EI_HAIRPIN_SRC_N_NEXT,
+} nat44_ei_hairpin_src_next_t;
+
+typedef enum
+{
+  NAT44_EI_HAIRPIN_NEXT_LOOKUP,
+  NAT44_EI_HAIRPIN_NEXT_DROP,
+  NAT44_EI_HAIRPIN_NEXT_HANDOFF,
+  NAT44_EI_HAIRPIN_N_NEXT,
+} nat44_ei_hairpin_next_t;
+
+typedef struct
+{
+  ip4_address_t addr;
+  u16 port;
+  u32 fib_index;
+  u32 session_index;
+} nat44_ei_hairpin_trace_t;
+
+static u8 *
+format_nat44_ei_hairpin_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 *);
+  nat44_ei_hairpin_trace_t *t = va_arg (*args, nat44_ei_hairpin_trace_t *);
+
+  s = format (s, "new dst addr %U port %u fib-index %u", format_ip4_address,
+	      &t->addr, clib_net_to_host_u16 (t->port), t->fib_index);
+  if (~0 == t->session_index)
+    {
+      s = format (s, " is-static-mapping");
+    }
+  else
+    {
+      s = format (s, " session-index %u", t->session_index);
+    }
+
+  return s;
+}
+
+extern vnet_feature_arc_registration_t vnet_feat_arc_ip4_local;
+
+static_always_inline int
+nat44_ei_is_hairpinning (nat44_ei_main_t *nm, ip4_address_t *dst_addr)
+{
+  nat44_ei_address_t *ap;
+  clib_bihash_kv_8_8_t kv, value;
+
+  vec_foreach (ap, nm->addresses)
+    {
+      if (ap->addr.as_u32 == dst_addr->as_u32)
+	return 1;
+    }
+
+  init_nat_k (&kv, *dst_addr, 0, 0, 0);
+  if (!clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv, &value))
+    return 1;
+
+  return 0;
+}
+
+#ifndef CLIB_MARCH_VARIANT
+void
+nat44_ei_hairpinning_sm_unknown_proto (nat44_ei_main_t *nm, vlib_buffer_t *b,
+				       ip4_header_t *ip)
+{
+  clib_bihash_kv_8_8_t kv, value;
+  nat44_ei_static_mapping_t *m;
+  u32 old_addr, new_addr;
+  ip_csum_t sum;
+
+  init_nat_k (&kv, ip->dst_address, 0, 0, 0);
+  if (clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv, &value))
+    return;
+
+  m = pool_elt_at_index (nm->static_mappings, value.value);
+
+  old_addr = ip->dst_address.as_u32;
+  new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
+  sum = ip->checksum;
+  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
+  ip->checksum = ip_csum_fold (sum);
+
+  if (vnet_buffer (b)->sw_if_index[VLIB_TX] == ~0)
+    vnet_buffer (b)->sw_if_index[VLIB_TX] = m->fib_index;
+}
+#endif
+
+#ifndef CLIB_MARCH_VARIANT
+int
+nat44_ei_hairpinning (vlib_main_t *vm, vlib_node_runtime_t *node,
+		      nat44_ei_main_t *nm, u32 thread_index, vlib_buffer_t *b0,
+		      ip4_header_t *ip0, udp_header_t *udp0,
+		      tcp_header_t *tcp0, u32 proto0, int do_trace,
+		      u32 *required_thread_index)
+{
+  nat44_ei_session_t *s0 = NULL;
+  clib_bihash_kv_8_8_t kv0, value0;
+  ip_csum_t sum0;
+  u32 new_dst_addr0 = 0, old_dst_addr0, si = ~0;
+  u16 new_dst_port0 = ~0, old_dst_port0;
+  int rv;
+  ip4_address_t sm0_addr;
+  u16 sm0_port;
+  u32 sm0_fib_index;
+  u32 old_sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_TX];
+
+  /* Check if destination is static mappings */
+  if (!nat44_ei_static_mapping_match (
+	ip0->dst_address, udp0->dst_port, nm->outside_fib_index, proto0,
+	&sm0_addr, &sm0_port, &sm0_fib_index, 1 /* by external */, 0, 0))
+    {
+      new_dst_addr0 = sm0_addr.as_u32;
+      new_dst_port0 = sm0_port;
+      vnet_buffer (b0)->sw_if_index[VLIB_TX] = sm0_fib_index;
+    }
+  /* or active session */
+  else
+    {
+      init_nat_k (&kv0, ip0->dst_address, udp0->dst_port,
+		  nm->outside_fib_index, proto0);
+      rv = clib_bihash_search_8_8 (&nm->out2in, &kv0, &value0);
+      if (rv)
+	{
+	  rv = 0;
+	  goto trace;
+	}
+
+      if (thread_index != nat_value_get_thread_index (&value0))
+	{
+	  *required_thread_index = nat_value_get_thread_index (&value0);
+	  return 0;
+	}
+
+      si = nat_value_get_session_index (&value0);
+      s0 = pool_elt_at_index (nm->per_thread_data[thread_index].sessions, si);
+      new_dst_addr0 = s0->in2out.addr.as_u32;
+      new_dst_port0 = s0->in2out.port;
+      vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+    }
+
+  /* Check if anything has changed and if not, then return 0. This
+     helps avoid infinite loop, repeating the three nodes
+     nat44-hairpinning-->ip4-lookup-->ip4-local, in case nothing has
+     changed. */
+  old_dst_addr0 = ip0->dst_address.as_u32;
+  old_dst_port0 = tcp0->dst;
+  if (new_dst_addr0 == old_dst_addr0 && new_dst_port0 == old_dst_port0 &&
+      vnet_buffer (b0)->sw_if_index[VLIB_TX] == old_sw_if_index)
+    return 0;
+
+  /* Destination is behind the same NAT, use internal address and port */
+  if (new_dst_addr0)
+    {
+      old_dst_addr0 = ip0->dst_address.as_u32;
+      ip0->dst_address.as_u32 = new_dst_addr0;
+      sum0 = ip0->checksum;
+      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0, ip4_header_t,
+			     dst_address);
+      ip0->checksum = ip_csum_fold (sum0);
+
+      old_dst_port0 = tcp0->dst;
+      if (PREDICT_TRUE (new_dst_port0 != old_dst_port0))
+	{
+	  if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
+	    {
+	      tcp0->dst = new_dst_port0;
+	      sum0 = tcp0->checksum;
+	      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0,
+				     ip4_header_t, dst_address);
+	      sum0 = ip_csum_update (sum0, old_dst_port0, new_dst_port0,
+				     ip4_header_t /* cheat */, length);
+	      tcp0->checksum = ip_csum_fold (sum0);
+	    }
+	  else
+	    {
+	      udp0->dst_port = new_dst_port0;
+	      udp0->checksum = 0;
+	    }
+	}
+      else
+	{
+	  if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
+	    {
+	      sum0 = tcp0->checksum;
+	      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0,
+				     ip4_header_t, dst_address);
+	      tcp0->checksum = ip_csum_fold (sum0);
+	    }
+	}
+      rv = 1;
+      goto trace;
+    }
+  rv = 0;
+trace:
+  if (do_trace && PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
+				 (b0->flags & VLIB_BUFFER_IS_TRACED)))
+    {
+      nat44_ei_hairpin_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
+      t->addr.as_u32 = new_dst_addr0;
+      t->port = new_dst_port0;
+      t->fib_index = vnet_buffer (b0)->sw_if_index[VLIB_TX];
+      if (s0)
+	{
+	  t->session_index = si;
+	}
+      else
+	{
+	  t->session_index = ~0;
+	}
+    }
+  return rv;
+}
+#endif
+
+#ifndef CLIB_MARCH_VARIANT
+u32
+nat44_ei_icmp_hairpinning (nat44_ei_main_t *nm, vlib_buffer_t *b0,
+			   u32 thread_index, ip4_header_t *ip0,
+			   icmp46_header_t *icmp0, u32 *required_thread_index)
+{
+  clib_bihash_kv_8_8_t kv0, value0;
+  u32 old_dst_addr0, new_dst_addr0;
+  u32 old_addr0, new_addr0;
+  u16 old_port0, new_port0;
+  u16 old_checksum0, new_checksum0;
+  u32 si, ti = 0;
+  ip_csum_t sum0;
+  nat44_ei_session_t *s0;
+  nat44_ei_static_mapping_t *m0;
+
+  if (icmp_type_is_error_message (
+	vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags))
+    {
+      ip4_header_t *inner_ip0 = 0;
+      tcp_udp_header_t *l4_header = 0;
+
+      inner_ip0 = (ip4_header_t *) ((icmp_echo_header_t *) (icmp0 + 1) + 1);
+      l4_header = ip4_next_header (inner_ip0);
+      u32 protocol = ip_proto_to_nat_proto (inner_ip0->protocol);
+
+      if (protocol != NAT_PROTOCOL_TCP && protocol != NAT_PROTOCOL_UDP)
+	return 1;
+
+      init_nat_k (&kv0, ip0->dst_address, l4_header->src_port,
+		  nm->outside_fib_index, protocol);
+      if (clib_bihash_search_8_8 (&nm->out2in, &kv0, &value0))
+	return 1;
+      ti = nat_value_get_thread_index (&value0);
+      if (ti != thread_index)
+	{
+	  *required_thread_index = ti;
+	  return 1;
+	}
+      si = nat_value_get_session_index (&value0);
+      s0 = pool_elt_at_index (nm->per_thread_data[ti].sessions, si);
+      new_dst_addr0 = s0->in2out.addr.as_u32;
+      vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+
+      /* update inner source IP address */
+      old_addr0 = inner_ip0->src_address.as_u32;
+      inner_ip0->src_address.as_u32 = new_dst_addr0;
+      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);
+      icmp0->checksum = ip_csum_fold (sum0);
+
+      /* update inner IP header checksum */
+      old_checksum0 = inner_ip0->checksum;
+      sum0 = inner_ip0->checksum;
+      sum0 =
+	ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t, src_address);
+      inner_ip0->checksum = ip_csum_fold (sum0);
+      new_checksum0 = inner_ip0->checksum;
+      sum0 = icmp0->checksum;
+      sum0 = ip_csum_update (sum0, old_checksum0, new_checksum0, ip4_header_t,
+			     checksum);
+      icmp0->checksum = ip_csum_fold (sum0);
+
+      /* update inner source port */
+      old_port0 = l4_header->src_port;
+      l4_header->src_port = s0->in2out.port;
+      new_port0 = l4_header->src_port;
+      sum0 = icmp0->checksum;
+      sum0 = ip_csum_update (sum0, old_port0, new_port0, tcp_udp_header_t,
+			     src_port);
+      icmp0->checksum = ip_csum_fold (sum0);
+    }
+  else
+    {
+      init_nat_k (&kv0, ip0->dst_address, 0, nm->outside_fib_index, 0);
+      if (clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv0,
+				  &value0))
+	{
+	  icmp_echo_header_t *echo0 = (icmp_echo_header_t *) (icmp0 + 1);
+	  u16 icmp_id0 = echo0->identifier;
+	  init_nat_k (&kv0, ip0->dst_address, icmp_id0, nm->outside_fib_index,
+		      NAT_PROTOCOL_ICMP);
+	  int rv = clib_bihash_search_8_8 (&nm->out2in, &kv0, &value0);
+	  if (!rv)
+	    {
+	      ti = nat_value_get_thread_index (&value0);
+	      if (ti != thread_index)
+		{
+		  *required_thread_index = ti;
+		  return 1;
+		}
+	      si = nat_value_get_session_index (&value0);
+	      s0 = pool_elt_at_index (nm->per_thread_data[ti].sessions, si);
+	      new_dst_addr0 = s0->in2out.addr.as_u32;
+	      vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+	      echo0->identifier = s0->in2out.port;
+	      sum0 = icmp0->checksum;
+	      sum0 = ip_csum_update (sum0, icmp_id0, s0->in2out.port,
+				     icmp_echo_header_t, identifier);
+	      icmp0->checksum = ip_csum_fold (sum0);
+	      goto change_addr;
+	    }
+
+	  return 1;
+	}
+
+      m0 = pool_elt_at_index (nm->static_mappings, value0.value);
+
+      new_dst_addr0 = m0->local_addr.as_u32;
+      if (vnet_buffer (b0)->sw_if_index[VLIB_TX] == ~0)
+	vnet_buffer (b0)->sw_if_index[VLIB_TX] = m0->fib_index;
+    }
+change_addr:
+  /* Destination is behind the same NAT, use internal address and port */
+  if (new_dst_addr0)
+    {
+      old_dst_addr0 = ip0->dst_address.as_u32;
+      ip0->dst_address.as_u32 = new_dst_addr0;
+      sum0 = ip0->checksum;
+      sum0 = ip_csum_update (sum0, old_dst_addr0, new_dst_addr0, ip4_header_t,
+			     dst_address);
+      ip0->checksum = ip_csum_fold (sum0);
+    }
+  return 0;
+}
+#endif
+
+void nat44_ei_hairpinning_unknown_proto (nat44_ei_main_t *nm, vlib_buffer_t *b,
+					 ip4_header_t *ip);
+
+#ifndef CLIB_MARCH_VARIANT
+void
+nat44_ei_hairpinning_unknown_proto (nat44_ei_main_t *nm, vlib_buffer_t *b,
+				    ip4_header_t *ip)
+{
+  clib_bihash_kv_8_8_t kv, value;
+  nat44_ei_static_mapping_t *m;
+  u32 old_addr, new_addr;
+  ip_csum_t sum;
+
+  init_nat_k (&kv, ip->dst_address, 0, 0, 0);
+  if (clib_bihash_search_8_8 (&nm->static_mapping_by_external, &kv, &value))
+    return;
+
+  m = pool_elt_at_index (nm->static_mappings, value.value);
+
+  old_addr = ip->dst_address.as_u32;
+  new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
+  sum = ip->checksum;
+  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
+  ip->checksum = ip_csum_fold (sum);
+
+  if (vnet_buffer (b)->sw_if_index[VLIB_TX] == ~0)
+    vnet_buffer (b)->sw_if_index[VLIB_TX] = m->fib_index;
+}
+#endif
+
+VLIB_NODE_FN (nat44_ei_hairpin_src_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  u32 n_left_from, *from, *to_next;
+  nat44_ei_hairpin_src_next_t next_index;
+  nat44_ei_main_t *nm = &nat44_ei_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 > 0 && n_left_to_next > 0)
+	{
+	  u32 bi0;
+	  vlib_buffer_t *b0;
+	  u32 next0;
+	  nat44_ei_interface_t *i;
+	  u32 sw_if_index0;
+
+	  /* 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);
+	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+	  vnet_feature_next (&next0, b0);
+
+	  pool_foreach (i, nm->output_feature_interfaces)
+	    {
+	      /* Only packets from NAT inside interface */
+	      if ((nat44_ei_interface_is_inside (i)) &&
+		  (sw_if_index0 == i->sw_if_index))
+		{
+		  if (PREDICT_FALSE ((vnet_buffer (b0)->snat.flags) &
+				     NAT44_EI_FLAG_HAIRPINNING))
+		    {
+		      if (PREDICT_TRUE (nm->num_workers > 1))
+			next0 = NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT_WH;
+		      else
+			next0 = NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT;
+		    }
+		  break;
+		}
+	    }
+
+	  if (next0 != NAT44_EI_HAIRPIN_SRC_NEXT_DROP)
+	    {
+	      vlib_increment_simple_counter (
+		&nm->counters.hairpinning, vm->thread_index, sw_if_index0, 1);
+	    }
+
+	  /* 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);
+    }
+
+  return frame->n_vectors;
+}
+
+VLIB_NODE_FN (nat44_ei_hairpin_dst_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  u32 n_left_from, *from, *to_next;
+  u32 thread_index = vm->thread_index;
+  nat44_ei_hairpin_next_t next_index;
+  nat44_ei_main_t *nm = &nat44_ei_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 > 0 && n_left_to_next > 0)
+	{
+	  u32 bi0;
+	  vlib_buffer_t *b0;
+	  u32 next0;
+	  ip4_header_t *ip0;
+	  u32 proto0;
+	  u32 sw_if_index0;
+	  u32 required_thread_index = thread_index;
+
+	  /* 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);
+	  next0 = NAT44_EI_HAIRPIN_NEXT_LOOKUP;
+	  ip0 = vlib_buffer_get_current (b0);
+	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+
+	  proto0 = ip_proto_to_nat_proto (ip0->protocol);
+
+	  vnet_buffer (b0)->snat.flags = 0;
+	  if (PREDICT_FALSE (nat44_ei_is_hairpinning (nm, &ip0->dst_address)))
+	    {
+	      if (proto0 == NAT_PROTOCOL_TCP || proto0 == NAT_PROTOCOL_UDP)
+		{
+		  udp_header_t *udp0 = ip4_next_header (ip0);
+		  tcp_header_t *tcp0 = (tcp_header_t *) udp0;
+
+		  nat44_ei_hairpinning (vm, node, nm, thread_index, b0, ip0,
+					udp0, tcp0, proto0, 1 /* do_trace */,
+					&required_thread_index);
+		}
+	      else if (proto0 == NAT_PROTOCOL_ICMP)
+		{
+		  icmp46_header_t *icmp0 = ip4_next_header (ip0);
+
+		  nat44_ei_icmp_hairpinning (nm, b0, thread_index, ip0, icmp0,
+					     &required_thread_index);
+		}
+	      else
+		{
+		  nat44_ei_hairpinning_unknown_proto (nm, b0, ip0);
+		}
+
+	      vnet_buffer (b0)->snat.flags = NAT44_EI_FLAG_HAIRPINNING;
+	    }
+
+	  if (thread_index != required_thread_index)
+	    {
+	      vnet_buffer (b0)->snat.required_thread_index =
+		required_thread_index;
+	      next0 = NAT44_EI_HAIRPIN_NEXT_HANDOFF;
+	    }
+
+	  if (next0 != NAT44_EI_HAIRPIN_NEXT_DROP)
+	    {
+	      vlib_increment_simple_counter (
+		&nm->counters.hairpinning, vm->thread_index, sw_if_index0, 1);
+	    }
+
+	  /* 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);
+    }
+
+  return frame->n_vectors;
+}
+
+VLIB_NODE_FN (nat44_ei_hairpinning_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  u32 n_left_from, *from, *to_next;
+  u32 thread_index = vm->thread_index;
+  nat44_ei_hairpin_next_t next_index;
+  nat44_ei_main_t *nm = &nat44_ei_main;
+  vnet_feature_main_t *fm = &feature_main;
+  u8 arc_index = vnet_feat_arc_ip4_local.feature_arc_index;
+  vnet_feature_config_main_t *cm = &fm->feature_config_mains[arc_index];
+
+  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;
+	  ip4_header_t *ip0;
+	  u32 proto0;
+	  udp_header_t *udp0;
+	  tcp_header_t *tcp0;
+	  u32 sw_if_index0;
+	  u32 required_thread_index = thread_index;
+
+	  /* 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];
+
+	  proto0 = ip_proto_to_nat_proto (ip0->protocol);
+	  int next0_resolved = 0;
+
+	  if (nat44_ei_hairpinning (vm, node, nm, thread_index, b0, ip0, udp0,
+				    tcp0, proto0, 1 /* do_trace */,
+				    &required_thread_index))
+	    {
+	      next0 = NAT44_EI_HAIRPIN_NEXT_LOOKUP;
+	      next0_resolved = 1;
+	    }
+
+	  if (thread_index != required_thread_index)
+	    {
+	      vnet_buffer (b0)->snat.required_thread_index =
+		required_thread_index;
+	      next0 = NAT44_EI_HAIRPIN_NEXT_HANDOFF;
+	      next0_resolved = 1;
+	    }
+
+	  if (!next0_resolved)
+	    vnet_get_config_data (&cm->config_main, &b0->current_config_index,
+				  &next0, 0);
+
+	  if (next0 != NAT44_EI_HAIRPIN_NEXT_DROP)
+	    {
+	      vlib_increment_simple_counter (
+		&nm->counters.hairpinning, vm->thread_index, sw_if_index0, 1);
+	    }
+
+	  /* 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);
+    }
+
+  return frame->n_vectors;
+}
+
+VLIB_NODE_FN (nat44_ei_hairpinning_dst_handoff_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  return nat44_ei_hairpinning_handoff_fn_inline (
+    vm, node, frame, nat44_ei_main.hairpin_dst_fq_index);
+}
+
+VLIB_NODE_FN (nat44_ei_hairpinning_handoff_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  return nat44_ei_hairpinning_handoff_fn_inline (
+    vm, node, frame, nat44_ei_main.hairpinning_fq_index);
+}
+
+VLIB_REGISTER_NODE (nat44_ei_hairpinning_dst_handoff_node) = {
+  .name = "nat44-ei-hairpin-dst-handoff",
+  .vector_size = sizeof (u32),
+  .n_errors = ARRAY_LEN(nat44_ei_hairpinning_handoff_error_strings),
+  .error_strings = nat44_ei_hairpinning_handoff_error_strings,
+  .format_trace = format_nat44_ei_hairpinning_handoff_trace,
+
+  .n_next_nodes = 1,
+
+  .next_nodes = {
+    [0] = "error-drop",
+  },
+};
+
+VLIB_REGISTER_NODE (nat44_ei_hairpinning_handoff_node) = {
+  .name = "nat44-ei-hairpinning-handoff",
+  .vector_size = sizeof (u32),
+  .n_errors = ARRAY_LEN(nat44_ei_hairpinning_handoff_error_strings),
+  .error_strings = nat44_ei_hairpinning_handoff_error_strings,
+  .format_trace = format_nat44_ei_hairpinning_handoff_trace,
+
+  .n_next_nodes = 1,
+
+  .next_nodes = {
+    [0] = "error-drop",
+  },
+};
+
+VLIB_REGISTER_NODE (nat44_ei_hairpin_src_node) = {
+  .name = "nat44-ei-hairpin-src",
+  .vector_size = sizeof (u32),
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_next_nodes = NAT44_EI_HAIRPIN_SRC_N_NEXT,
+  .next_nodes = {
+     [NAT44_EI_HAIRPIN_SRC_NEXT_DROP] = "error-drop",
+     [NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT] = "nat44-ei-in2out-output",
+     [NAT44_EI_HAIRPIN_SRC_NEXT_INTERFACE_OUTPUT] = "interface-output",
+     [NAT44_EI_HAIRPIN_SRC_NEXT_SNAT_IN2OUT_WH] = "nat44-ei-in2out-output-worker-handoff",
+  },
+};
+
+VLIB_REGISTER_NODE (nat44_ei_hairpin_dst_node) = {
+  .name = "nat44-ei-hairpin-dst",
+  .vector_size = sizeof (u32),
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .format_trace = format_nat44_ei_hairpin_trace,
+  .n_next_nodes = NAT44_EI_HAIRPIN_N_NEXT,
+  .next_nodes = {
+    [NAT44_EI_HAIRPIN_NEXT_DROP] = "error-drop",
+    [NAT44_EI_HAIRPIN_NEXT_LOOKUP] = "ip4-lookup",
+    [NAT44_EI_HAIRPIN_NEXT_HANDOFF] = "nat44-ei-hairpin-dst-handoff",
+  },
+};
+
+VLIB_REGISTER_NODE (nat44_ei_hairpinning_node) = {
+  .name = "nat44-ei-hairpinning",
+  .vector_size = sizeof (u32),
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .format_trace = format_nat44_ei_hairpin_trace,
+  .n_next_nodes = NAT44_EI_HAIRPIN_N_NEXT,
+  .next_nodes = {
+    [NAT44_EI_HAIRPIN_NEXT_DROP] = "error-drop",
+    [NAT44_EI_HAIRPIN_NEXT_LOOKUP] = "ip4-lookup",
+    [NAT44_EI_HAIRPIN_NEXT_HANDOFF] = "nat44-ei-hairpinning-handoff",
+  },
+};
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */