nat: move nat64 to a subfeature

Type: refactor

Change-Id: I3b9e17164647d2019b1f40cffeed63393345219e
Signed-off-by: Filip Varga <fivarga@cisco.com>

1 files changed, 796 insertions, 0 deletions

diff --git a/src/plugins/nat/nat64/nat64_out2in.c b/src/plugins/nat/nat64/nat64_out2in.c
new file mode 100644
index 00000000000..108edf0bdd1
--- /dev/null
+++ b/src/plugins/nat/nat64/nat64_out2in.c
@@ -0,0 +1,796 @@
+/*
+ * 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 <nat/nat64/nat64.h>
+#include <vnet/ip/ip4_to_ip6.h>
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/udp/udp.h>
+
+typedef struct
+{
+  u32 sw_if_index;
+  u32 next_index;
+} nat64_out2in_trace_t;
+
+static u8 *
+format_nat64_out2in_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 *);
+  nat64_out2in_trace_t *t = va_arg (*args, nat64_out2in_trace_t *);
+
+  s =
+    format (s, "NAT64-out2in: sw_if_index %d, next index %d", t->sw_if_index,
+	    t->next_index);
+
+  return s;
+}
+
+#define foreach_nat64_out2in_error                       \
+_(UNSUPPORTED_PROTOCOL, "unsupported protocol")          \
+_(NO_TRANSLATION, "no translation")                      \
+_(UNKNOWN, "unknown")
+
+typedef enum
+{
+#define _(sym,str) NAT64_OUT2IN_ERROR_##sym,
+  foreach_nat64_out2in_error
+#undef _
+    NAT64_OUT2IN_N_ERROR,
+} nat64_out2in_error_t;
+
+static char *nat64_out2in_error_strings[] = {
+#define _(sym,string) string,
+  foreach_nat64_out2in_error
+#undef _
+};
+
+typedef enum
+{
+  NAT64_OUT2IN_NEXT_IP6_LOOKUP,
+  NAT64_OUT2IN_NEXT_IP4_LOOKUP,
+  NAT64_OUT2IN_NEXT_DROP,
+  NAT64_OUT2IN_N_NEXT,
+} nat64_out2in_next_t;
+
+typedef struct nat64_out2in_set_ctx_t_
+{
+  vlib_buffer_t *b;
+  vlib_main_t *vm;
+  u32 thread_index;
+} nat64_out2in_set_ctx_t;
+
+static int
+nat64_out2in_tcp_udp (vlib_main_t * vm, vlib_buffer_t * b,
+		      nat64_out2in_set_ctx_t * ctx)
+{
+  ip4_header_t *ip4;
+  ip6_header_t *ip6;
+  ip_csum_t csum;
+  u16 *checksum = NULL;
+  ip6_frag_hdr_t *frag;
+  u32 frag_id;
+  ip4_address_t old_src, old_dst;
+
+  nat64_main_t *nm = &nat64_main;
+  nat64_db_bib_entry_t *bibe;
+  nat64_db_st_entry_t *ste;
+  ip46_address_t saddr;
+  ip46_address_t daddr;
+  ip6_address_t ip6_saddr;
+  u8 proto = vnet_buffer (b)->ip.reass.ip_proto;
+  u16 dport = vnet_buffer (b)->ip.reass.l4_dst_port;
+  u16 sport = vnet_buffer (b)->ip.reass.l4_src_port;
+  u32 sw_if_index, fib_index;
+  nat64_db_t *db = &nm->db[ctx->thread_index];
+
+  ip4 = vlib_buffer_get_current (b);
+
+  udp_header_t *udp = ip4_next_header (ip4);
+  tcp_header_t *tcp = ip4_next_header (ip4);
+  if (!vnet_buffer (b)->ip.reass.is_non_first_fragment)
+    {
+      if (ip4->protocol == IP_PROTOCOL_UDP)
+	{
+	  checksum = &udp->checksum;
+	  //UDP checksum is optional over IPv4 but mandatory for IPv6
+	  //We do not check udp->length sanity but use our safe computed value instead
+	  if (PREDICT_FALSE (!*checksum))
+	    {
+	      u16 udp_len =
+		clib_host_to_net_u16 (ip4->length) - sizeof (*ip4);
+	      csum = ip_incremental_checksum (0, udp, udp_len);
+	      csum =
+		ip_csum_with_carry (csum, clib_host_to_net_u16 (udp_len));
+	      csum =
+		ip_csum_with_carry (csum,
+				    clib_host_to_net_u16 (IP_PROTOCOL_UDP));
+	      csum =
+		ip_csum_with_carry (csum, *((u64 *) (&ip4->src_address)));
+	      *checksum = ~ip_csum_fold (csum);
+	    }
+	}
+      else
+	{
+	  checksum = &tcp->checksum;
+	}
+    }
+
+  old_src.as_u32 = ip4->src_address.as_u32;
+  old_dst.as_u32 = ip4->dst_address.as_u32;
+
+  // Deal with fragmented packets
+  u16 frag_offset = ip4_get_fragment_offset (ip4);
+  if (PREDICT_FALSE (ip4_get_fragment_more (ip4) || frag_offset))
+    {
+      ip6 =
+	(ip6_header_t *) u8_ptr_add (ip4,
+				     sizeof (*ip4) - sizeof (*ip6) -
+				     sizeof (*frag));
+      frag =
+	(ip6_frag_hdr_t *) u8_ptr_add (ip4, sizeof (*ip4) - sizeof (*frag));
+      frag_id = frag_id_4to6 (ip4->fragment_id);
+      vlib_buffer_advance (b, sizeof (*ip4) - sizeof (*ip6) - sizeof (*frag));
+    }
+  else
+    {
+      ip6 = (ip6_header_t *) (((u8 *) ip4) + sizeof (*ip4) - sizeof (*ip6));
+      vlib_buffer_advance (b, sizeof (*ip4) - sizeof (*ip6));
+      frag = NULL;
+    }
+
+  ip6->ip_version_traffic_class_and_flow_label =
+    clib_host_to_net_u32 ((6 << 28) + (ip4->tos << 20));
+  ip6->payload_length = u16_net_add (ip4->length, -sizeof (*ip4));
+  ip6->hop_limit = ip4->ttl;
+  ip6->protocol = ip4->protocol;
+
+  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
+  fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);
+
+  clib_memset (&saddr, 0, sizeof (saddr));
+  saddr.ip4.as_u32 = ip4->src_address.as_u32;
+  clib_memset (&daddr, 0, sizeof (daddr));
+  daddr.ip4.as_u32 = ip4->dst_address.as_u32;
+
+  ste =
+    nat64_db_st_entry_find (db, &daddr, &saddr, dport, sport, proto,
+			    fib_index, 0);
+  if (ste)
+    {
+      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
+      if (!bibe)
+	return -1;
+    }
+  else
+    {
+      bibe = nat64_db_bib_entry_find (db, &daddr, dport, proto, fib_index, 0);
+
+      if (!bibe)
+	return -1;
+
+      nat64_compose_ip6 (&ip6_saddr, &old_src, bibe->fib_index);
+      ste =
+	nat64_db_st_entry_create (ctx->thread_index, db, bibe, &ip6_saddr,
+				  &saddr.ip4, sport);
+
+      if (!ste)
+	return -1;
+
+      vlib_set_simple_counter (&nm->total_sessions, ctx->thread_index, 0,
+			       db->st.st_entries_num);
+    }
+
+  ip6->src_address.as_u64[0] = ste->in_r_addr.as_u64[0];
+  ip6->src_address.as_u64[1] = ste->in_r_addr.as_u64[1];
+
+  ip6->dst_address.as_u64[0] = bibe->in_addr.as_u64[0];
+  ip6->dst_address.as_u64[1] = bibe->in_addr.as_u64[1];
+
+  vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
+
+  nat64_session_reset_timeout (ste, ctx->vm);
+
+  if (PREDICT_FALSE (frag != NULL))
+    {
+      frag->next_hdr = ip6->protocol;
+      frag->identification = frag_id;
+      frag->rsv = 0;
+      frag->fragment_offset_and_more =
+	ip6_frag_hdr_offset_and_more (frag_offset, 1);
+      ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
+      ip6->payload_length = u16_net_add (ip6->payload_length, sizeof (*frag));
+    }
+
+  if (!vnet_buffer (b)->ip.reass.is_non_first_fragment)
+    {
+      udp->dst_port = bibe->in_port;
+
+      if (proto == IP_PROTOCOL_TCP)
+	{
+	  nat64_tcp_session_set_state (ste, tcp, 0);
+	}
+
+      csum = ip_csum_sub_even (*checksum, dport);
+      csum = ip_csum_add_even (csum, udp->dst_port);
+      csum = ip_csum_sub_even (csum, old_src.as_u32);
+      csum = ip_csum_sub_even (csum, old_dst.as_u32);
+      csum = ip_csum_add_even (csum, ip6->src_address.as_u64[0]);
+      csum = ip_csum_add_even (csum, ip6->src_address.as_u64[1]);
+      csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[0]);
+      csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[1]);
+      *checksum = ip_csum_fold (csum);
+    }
+
+  return 0;
+}
+
+static int
+nat64_out2in_icmp_set_cb (vlib_buffer_t * b, ip4_header_t * ip4,
+			  ip6_header_t * ip6, void *arg)
+{
+  nat64_main_t *nm = &nat64_main;
+  nat64_out2in_set_ctx_t *ctx = arg;
+  nat64_db_bib_entry_t *bibe;
+  nat64_db_st_entry_t *ste;
+  ip46_address_t saddr, daddr;
+  ip6_address_t ip6_saddr;
+  u32 sw_if_index, fib_index;
+  icmp46_header_t *icmp = ip4_next_header (ip4);
+  nat64_db_t *db = &nm->db[ctx->thread_index];
+
+  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
+  fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);
+
+  clib_memset (&saddr, 0, sizeof (saddr));
+  saddr.ip4.as_u32 = ip4->src_address.as_u32;
+  clib_memset (&daddr, 0, sizeof (daddr));
+  daddr.ip4.as_u32 = ip4->dst_address.as_u32;
+
+  if (icmp->type == ICMP6_echo_request || icmp->type == ICMP6_echo_reply)
+    {
+      u16 out_id = ((u16 *) (icmp))[2];
+      ste =
+	nat64_db_st_entry_find (db, &daddr, &saddr, out_id, 0,
+				IP_PROTOCOL_ICMP, fib_index, 0);
+
+      if (ste)
+	{
+	  bibe =
+	    nat64_db_bib_entry_by_index (db, IP_PROTOCOL_ICMP,
+					 ste->bibe_index);
+	  if (!bibe)
+	    return -1;
+	}
+      else
+	{
+	  bibe =
+	    nat64_db_bib_entry_find (db, &daddr, out_id,
+				     IP_PROTOCOL_ICMP, fib_index, 0);
+	  if (!bibe)
+	    return -1;
+
+	  nat64_compose_ip6 (&ip6_saddr, &ip4->src_address, bibe->fib_index);
+	  ste =
+	    nat64_db_st_entry_create (ctx->thread_index, db,
+				      bibe, &ip6_saddr, &saddr.ip4, 0);
+
+	  if (!ste)
+	    return -1;
+
+	  vlib_set_simple_counter (&nm->total_sessions, ctx->thread_index, 0,
+				   db->st.st_entries_num);
+	}
+
+      nat64_session_reset_timeout (ste, ctx->vm);
+
+      ip6->src_address.as_u64[0] = ste->in_r_addr.as_u64[0];
+      ip6->src_address.as_u64[1] = ste->in_r_addr.as_u64[1];
+
+      ip6->dst_address.as_u64[0] = bibe->in_addr.as_u64[0];
+      ip6->dst_address.as_u64[1] = bibe->in_addr.as_u64[1];
+      ((u16 *) (icmp))[2] = bibe->in_port;
+
+      vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
+    }
+  else
+    {
+      ip6_header_t *inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8);
+
+      nat64_compose_ip6 (&ip6->src_address, &ip4->src_address,
+			 vnet_buffer (ctx->b)->sw_if_index[VLIB_TX]);
+      ip6->dst_address.as_u64[0] = inner_ip6->src_address.as_u64[0];
+      ip6->dst_address.as_u64[1] = inner_ip6->src_address.as_u64[1];
+    }
+
+  return 0;
+}
+
+static int
+nat64_out2in_inner_icmp_set_cb (vlib_buffer_t * b, ip4_header_t * ip4,
+				ip6_header_t * ip6, void *arg)
+{
+  nat64_main_t *nm = &nat64_main;
+  nat64_out2in_set_ctx_t *ctx = arg;
+  nat64_db_bib_entry_t *bibe;
+  nat64_db_st_entry_t *ste;
+  ip46_address_t saddr, daddr;
+  u32 sw_if_index, fib_index;
+  u8 proto = ip4->protocol;
+  nat64_db_t *db = &nm->db[ctx->thread_index];
+
+  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
+  fib_index =
+    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6, sw_if_index);
+
+  clib_memset (&saddr, 0, sizeof (saddr));
+  saddr.ip4.as_u32 = ip4->src_address.as_u32;
+  clib_memset (&daddr, 0, sizeof (daddr));
+  daddr.ip4.as_u32 = ip4->dst_address.as_u32;
+
+  if (proto == IP_PROTOCOL_ICMP6)
+    {
+      icmp46_header_t *icmp = ip4_next_header (ip4);
+      u16 out_id = ((u16 *) (icmp))[2];
+      proto = IP_PROTOCOL_ICMP;
+
+      if (!
+	  (icmp->type == ICMP6_echo_request
+	   || icmp->type == ICMP6_echo_reply))
+	return -1;
+
+      ste =
+	nat64_db_st_entry_find (db, &saddr, &daddr, out_id, 0, proto,
+				fib_index, 0);
+      if (!ste)
+	return -1;
+
+      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
+      if (!bibe)
+	return -1;
+
+      ip6->dst_address.as_u64[0] = ste->in_r_addr.as_u64[0];
+      ip6->dst_address.as_u64[1] = ste->in_r_addr.as_u64[1];
+      ip6->src_address.as_u64[0] = bibe->in_addr.as_u64[0];
+      ip6->src_address.as_u64[1] = bibe->in_addr.as_u64[1];
+      ((u16 *) (icmp))[2] = bibe->in_port;
+
+      vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
+    }
+  else
+    {
+      udp_header_t *udp = ip4_next_header (ip4);
+      tcp_header_t *tcp = ip4_next_header (ip4);
+      u16 dport = udp->dst_port;
+      u16 sport = udp->src_port;
+      u16 *checksum;
+      ip_csum_t csum;
+
+      ste =
+	nat64_db_st_entry_find (db, &saddr, &daddr, sport, dport, proto,
+				fib_index, 0);
+      if (!ste)
+	return -1;
+
+      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
+      if (!bibe)
+	return -1;
+
+      nat64_compose_ip6 (&ip6->dst_address, &daddr.ip4, bibe->fib_index);
+      ip6->src_address.as_u64[0] = bibe->in_addr.as_u64[0];
+      ip6->src_address.as_u64[1] = bibe->in_addr.as_u64[1];
+      udp->src_port = bibe->in_port;
+
+      if (proto == IP_PROTOCOL_UDP)
+	checksum = &udp->checksum;
+      else
+	checksum = &tcp->checksum;
+      if (*checksum)
+	{
+	  csum = ip_csum_sub_even (*checksum, sport);
+	  csum = ip_csum_add_even (csum, udp->src_port);
+	  *checksum = ip_csum_fold (csum);
+	}
+
+      vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
+    }
+
+  return 0;
+}
+
+static int
+nat64_out2in_unk_proto (vlib_main_t * vm, vlib_buffer_t * p,
+			nat64_out2in_set_ctx_t * ctx)
+{
+  ip4_header_t *ip4 = vlib_buffer_get_current (p);
+  ip6_header_t *ip6;
+  ip6_frag_hdr_t *frag;
+  u32 frag_id;
+
+  nat64_main_t *nm = &nat64_main;
+  nat64_db_bib_entry_t *bibe;
+  nat64_db_st_entry_t *ste;
+  ip46_address_t saddr, daddr;
+  ip6_address_t ip6_saddr;
+  u32 sw_if_index, fib_index;
+  u8 proto = ip4->protocol;
+  nat64_db_t *db = &nm->db[ctx->thread_index];
+
+  // Deal with fragmented packets
+  u16 frag_offset = ip4_get_fragment_offset (ip4);
+  if (PREDICT_FALSE (ip4_get_fragment_more (ip4) || frag_offset))
+    {
+      ip6 =
+	(ip6_header_t *) u8_ptr_add (ip4,
+				     sizeof (*ip4) - sizeof (*ip6) -
+				     sizeof (*frag));
+      frag =
+	(ip6_frag_hdr_t *) u8_ptr_add (ip4, sizeof (*ip4) - sizeof (*frag));
+      frag_id = frag_id_4to6 (ip4->fragment_id);
+      vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6) - sizeof (*frag));
+    }
+  else
+    {
+      ip6 = (ip6_header_t *) (((u8 *) ip4) + sizeof (*ip4) - sizeof (*ip6));
+      vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6));
+      frag = NULL;
+    }
+
+  ip6->ip_version_traffic_class_and_flow_label =
+    clib_host_to_net_u32 ((6 << 28) + (ip4->tos << 20));
+  ip6->payload_length = u16_net_add (ip4->length, -sizeof (*ip4));
+  ip6->hop_limit = ip4->ttl;
+  ip6->protocol = ip4->protocol;
+
+  if (PREDICT_FALSE (frag != NULL))
+    {
+      frag->next_hdr = ip6->protocol;
+      frag->identification = frag_id;
+      frag->rsv = 0;
+      frag->fragment_offset_and_more =
+	ip6_frag_hdr_offset_and_more (frag_offset, 1);
+      ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
+      ip6->payload_length = u16_net_add (ip6->payload_length, sizeof (*frag));
+    }
+
+  sw_if_index = vnet_buffer (ctx->b)->sw_if_index[VLIB_RX];
+  fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);
+
+  clib_memset (&saddr, 0, sizeof (saddr));
+  saddr.ip4.as_u32 = ip4->src_address.as_u32;
+  clib_memset (&daddr, 0, sizeof (daddr));
+  daddr.ip4.as_u32 = ip4->dst_address.as_u32;
+
+  ste =
+    nat64_db_st_entry_find (db, &daddr, &saddr, 0, 0, proto, fib_index, 0);
+  if (ste)
+    {
+      bibe = nat64_db_bib_entry_by_index (db, proto, ste->bibe_index);
+      if (!bibe)
+	return -1;
+    }
+  else
+    {
+      bibe = nat64_db_bib_entry_find (db, &daddr, 0, proto, fib_index, 0);
+
+      if (!bibe)
+	return -1;
+
+      nat64_compose_ip6 (&ip6_saddr, &ip4->src_address, bibe->fib_index);
+      ste = nat64_db_st_entry_create (ctx->thread_index, db,
+				      bibe, &ip6_saddr, &saddr.ip4, 0);
+
+      if (!ste)
+	return -1;
+
+      vlib_set_simple_counter (&nm->total_sessions, ctx->thread_index, 0,
+			       db->st.st_entries_num);
+    }
+
+  nat64_session_reset_timeout (ste, ctx->vm);
+
+  ip6->src_address.as_u64[0] = ste->in_r_addr.as_u64[0];
+  ip6->src_address.as_u64[1] = ste->in_r_addr.as_u64[1];
+
+  ip6->dst_address.as_u64[0] = bibe->in_addr.as_u64[0];
+  ip6->dst_address.as_u64[1] = bibe->in_addr.as_u64[1];
+
+  vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
+
+  return 0;
+}
+
+VLIB_NODE_FN (nat64_out2in_node) (vlib_main_t * vm,
+				  vlib_node_runtime_t * node,
+				  vlib_frame_t * frame)
+{
+  u32 n_left_from, *from, *to_next;
+  nat64_out2in_next_t next_index;
+  nat64_main_t *nm = &nat64_main;
+  u32 thread_index = vm->thread_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 *ip40;
+	  u32 proto0;
+	  nat64_out2in_set_ctx_t ctx0;
+	  udp_header_t *udp0;
+	  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);
+	  ip40 = vlib_buffer_get_current (b0);
+
+	  ctx0.b = b0;
+	  ctx0.vm = vm;
+	  ctx0.thread_index = thread_index;
+
+	  next0 = NAT64_OUT2IN_NEXT_IP6_LOOKUP;
+
+	  proto0 = ip_proto_to_nat_proto (ip40->protocol);
+	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+	  if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_OTHER))
+	    {
+	      if (nat64_out2in_unk_proto (vm, b0, &ctx0))
+		{
+		  next0 = NAT64_OUT2IN_NEXT_DROP;
+		  b0->error = node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
+		}
+	      vlib_increment_simple_counter (&nm->counters.out2in.other,
+					     thread_index, sw_if_index0, 1);
+	      goto trace0;
+	    }
+
+	  if (proto0 == NAT_PROTOCOL_ICMP)
+	    {
+	      vlib_increment_simple_counter (&nm->counters.out2in.icmp,
+					     thread_index, sw_if_index0, 1);
+	      if (icmp_to_icmp6
+		  (b0, nat64_out2in_icmp_set_cb, &ctx0,
+		   nat64_out2in_inner_icmp_set_cb, &ctx0))
+		{
+		  next0 = NAT64_OUT2IN_NEXT_DROP;
+		  b0->error = node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
+		  goto trace0;
+		}
+	    }
+	  else
+	    {
+	      if (proto0 == NAT_PROTOCOL_TCP)
+		vlib_increment_simple_counter (&nm->counters.out2in.tcp,
+					       thread_index, sw_if_index0, 1);
+	      else
+		vlib_increment_simple_counter (&nm->counters.out2in.udp,
+					       thread_index, sw_if_index0, 1);
+
+	      if (nat64_out2in_tcp_udp (vm, b0, &ctx0))
+		{
+		  udp0 = ip4_next_header (ip40);
+		  /*
+		   * Send DHCP packets to the ipv4 stack, or we won't
+		   * be able to use dhcp client on the outside interface
+		   */
+		  if ((proto0 == NAT_PROTOCOL_UDP)
+		      && (udp0->dst_port ==
+			  clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_client)))
+		    {
+		      next0 = NAT64_OUT2IN_NEXT_IP4_LOOKUP;
+		      goto trace0;
+		    }
+		  next0 = NAT64_OUT2IN_NEXT_DROP;
+		  b0->error = node->errors[NAT64_OUT2IN_ERROR_NO_TRANSLATION];
+		  goto trace0;
+		}
+	    }
+
+	trace0:
+	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+			     && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+	    {
+	      nat64_out2in_trace_t *t =
+		vlib_add_trace (vm, node, b0, sizeof (*t));
+	      t->sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+	      t->next_index = next0;
+	    }
+
+	  if (next0 == NAT64_OUT2IN_NEXT_DROP)
+	    {
+	      vlib_increment_simple_counter (&nm->counters.out2in.drops,
+					     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;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat64_out2in_node) = {
+  .name = "nat64-out2in",
+  .vector_size = sizeof (u32),
+  .format_trace = format_nat64_out2in_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN (nat64_out2in_error_strings),
+  .error_strings = nat64_out2in_error_strings,
+  .n_next_nodes = NAT64_OUT2IN_N_NEXT,
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [NAT64_OUT2IN_NEXT_DROP] = "error-drop",
+    [NAT64_OUT2IN_NEXT_IP6_LOOKUP] = "ip6-lookup",
+    [NAT64_OUT2IN_NEXT_IP4_LOOKUP] = "ip4-lookup",
+  },
+};
+/* *INDENT-ON* */
+
+typedef struct nat64_out2in_frag_set_ctx_t_
+{
+  vlib_main_t *vm;
+  vlib_buffer_t *b;
+  u32 sess_index;
+  u32 thread_index;
+  u8 proto;
+  u8 first_frag;
+} nat64_out2in_frag_set_ctx_t;
+
+#define foreach_nat64_out2in_handoff_error                       \
+_(CONGESTION_DROP, "congestion drop")                            \
+_(SAME_WORKER, "same worker")                                    \
+_(DO_HANDOFF, "do handoff")
+
+typedef enum
+{
+#define _(sym,str) NAT64_OUT2IN_HANDOFF_ERROR_##sym,
+  foreach_nat64_out2in_handoff_error
+#undef _
+    NAT64_OUT2IN_HANDOFF_N_ERROR,
+} nat64_out2in_handoff_error_t;
+
+static char *nat64_out2in_handoff_error_strings[] = {
+#define _(sym,string) string,
+  foreach_nat64_out2in_handoff_error
+#undef _
+};
+
+typedef struct
+{
+  u32 next_worker_index;
+} nat64_out2in_handoff_trace_t;
+
+static u8 *
+format_nat64_out2in_handoff_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 *);
+  nat64_out2in_handoff_trace_t *t =
+    va_arg (*args, nat64_out2in_handoff_trace_t *);
+
+  s =
+    format (s, "NAT64-OUT2IN-HANDOFF: next-worker %d", t->next_worker_index);
+
+  return s;
+}
+
+VLIB_NODE_FN (nat64_out2in_handoff_node) (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame)
+{
+  nat64_main_t *nm = &nat64_main;
+  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
+  u32 n_enq, n_left_from, *from;
+  u16 thread_indices[VLIB_FRAME_SIZE], *ti;
+  u32 fq_index;
+  u32 thread_index = vm->thread_index;
+  u32 do_handoff = 0, same_worker = 0;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  vlib_get_buffers (vm, from, bufs, n_left_from);
+
+  b = bufs;
+  ti = thread_indices;
+
+  fq_index = nm->fq_out2in_index;
+
+  while (n_left_from > 0)
+    {
+      ip4_header_t *ip0;
+
+      ip0 = vlib_buffer_get_current (b[0]);
+      ti[0] = nat64_get_worker_out2in (b[0], ip0);
+
+      if (ti[0] != thread_index)
+	do_handoff++;
+      else
+	same_worker++;
+
+      if (PREDICT_FALSE
+	  ((node->flags & VLIB_NODE_FLAG_TRACE)
+	   && (b[0]->flags & VLIB_BUFFER_IS_TRACED)))
+	{
+	  nat64_out2in_handoff_trace_t *t =
+	    vlib_add_trace (vm, node, b[0], sizeof (*t));
+	  t->next_worker_index = ti[0];
+	}
+
+      n_left_from -= 1;
+      ti += 1;
+      b += 1;
+    }
+
+  n_enq =
+    vlib_buffer_enqueue_to_thread (vm, fq_index, from, thread_indices,
+				   frame->n_vectors, 1);
+
+  if (n_enq < frame->n_vectors)
+    vlib_node_increment_counter (vm, node->node_index,
+				 NAT64_OUT2IN_HANDOFF_ERROR_CONGESTION_DROP,
+				 frame->n_vectors - n_enq);
+  vlib_node_increment_counter (vm, node->node_index,
+			       NAT64_OUT2IN_HANDOFF_ERROR_SAME_WORKER,
+			       same_worker);
+  vlib_node_increment_counter (vm, node->node_index,
+			       NAT64_OUT2IN_HANDOFF_ERROR_DO_HANDOFF,
+			       do_handoff);
+
+  return frame->n_vectors;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat64_out2in_handoff_node) = {
+  .name = "nat64-out2in-handoff",
+  .vector_size = sizeof (u32),
+  .format_trace = format_nat64_out2in_handoff_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN(nat64_out2in_handoff_error_strings),
+  .error_strings = nat64_out2in_handoff_error_strings,
+
+  .n_next_nodes = 1,
+
+  .next_nodes = {
+    [0] = "error-drop",
+  },
+};
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */