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path: root/src/plugins/cnat/cnat_node.h
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}
/*
 * Copyright (c) 2015 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.
 */
/*
  Copyright (c) 2001-2005 Eliot Dresselhaus

  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:

  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#ifndef included_clib_smp_h
#define included_clib_smp_h

#include <vppinfra/cache.h>
#include <vppinfra/os.h>	/* for os_panic */

#define clib_smp_swap(addr,new) __sync_lock_test_and_set(addr,new)

#if defined (i386) || defined (__x86_64__)
#define clib_smp_pause() do { asm volatile ("pause"); } while (0)
#elif defined (__aarch64__) || defined (__arm__)
#define clib_smp_pause() do { asm volatile ("isb" ::: "memory"); } while (0)
#endif

#ifndef clib_smp_pause
#define clib_smp_pause() do { } while (0)
#endif

#ifdef CLIB_UNIX
#include <sched.h>

always_inline void
os_sched_yield (void)
{
  sched_yield ();
}
#else
always_inline void
os_sched_yield (void)
{
  clib_smp_pause ();
}
#endif


#endif /* included_clib_smp_h */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */
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/*
 * 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.
 */

#ifndef __CNAT_NODE_H__
#define __CNAT_NODE_H__

#include <vlibmemory/api.h>
#include <vnet/dpo/load_balance.h>
#include <vnet/dpo/load_balance_map.h>

#include <cnat/cnat_session.h>
#include <cnat/cnat_client.h>
#include <cnat/cnat_inline.h>
#include <cnat/cnat_translation.h>

#include <vnet/ip/ip4_inlines.h>
#include <vnet/ip/ip6_inlines.h>

typedef uword (*cnat_node_sub_t) (vlib_main_t * vm,
				  vlib_node_runtime_t * node,
				  vlib_buffer_t * b,
				  cnat_node_ctx_t * ctx, int rv,
				  cnat_session_t * session);

typedef struct cnat_trace_element_t_
{
  cnat_session_t session;
  cnat_translation_t tr;
  u32 sw_if_index[VLIB_N_RX_TX];
  u32 snat_policy_result;
  u8 flags;
} cnat_trace_element_t;

typedef enum cnat_trace_element_flag_t_
{
  CNAT_TRACE_SESSION_FOUND = (1 << 0),
  CNAT_TRACE_SESSION_CREATED = (1 << 1),
  CNAT_TRACE_TRANSLATION_FOUND = (1 << 2),
  CNAT_TRACE_NO_NAT = (1 << 3),
} cnat_trace_element_flag_t;

static_always_inline void
cnat_add_trace (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_buffer_t *b,
		cnat_session_t *session, const cnat_translation_t *ct,
		u8 flags)
{
  cnat_trace_element_t *t;
  if (NULL != ct)
    flags |= CNAT_TRACE_TRANSLATION_FOUND;

  t = vlib_add_trace (vm, node, b, sizeof (*t));
  t->sw_if_index[VLIB_RX] = vnet_buffer (b)->sw_if_index[VLIB_RX];
  t->sw_if_index[VLIB_TX] = vnet_buffer (b)->sw_if_index[VLIB_TX];

  if (flags & (CNAT_TRACE_SESSION_FOUND | CNAT_TRACE_SESSION_CREATED))
    clib_memcpy (&t->session, session, sizeof (t->session));
  if (flags & CNAT_TRACE_TRANSLATION_FOUND)
    clib_memcpy (&t->tr, ct, sizeof (cnat_translation_t));
  t->flags = flags;
}

static u8 *
format_cnat_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 *);
  cnat_trace_element_t *t = va_arg (*args, cnat_trace_element_t *);
  u32 indent = format_get_indent (s);
  vnet_main_t *vnm = vnet_get_main ();

  if (t->flags & CNAT_TRACE_SESSION_CREATED)
    s = format (s, "created session");
  else if (t->flags & CNAT_TRACE_SESSION_FOUND)
    s = format (s, "found session");
  else
    s = format (s, "session not found");

  if (t->flags & (CNAT_TRACE_NO_NAT))
    s = format (s, " [policy:skip]");

  s = format (s, "\n%Uin:%U out:%U ", format_white_space, indent,
	      format_vnet_sw_if_index_name, vnm, t->sw_if_index[VLIB_RX],
	      format_vnet_sw_if_index_name, vnm, t->sw_if_index[VLIB_TX]);

  if (t->flags & (CNAT_TRACE_SESSION_CREATED | CNAT_TRACE_SESSION_FOUND))
    s = format (s, "\n%U%U", format_white_space, indent, format_cnat_session,
		&t->session, 1);

  if (t->flags & CNAT_TRACE_TRANSLATION_FOUND)
    s = format (s, "\n%Utranslation: %U", format_white_space, indent,
		format_cnat_translation, &t->tr, 0);

  return s;
}

static_always_inline u8
icmp_type_is_error_message (u8 icmp_type)
{
  switch (icmp_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:
      return 1;
    }
  return 0;
}

static_always_inline u8
icmp_type_is_echo (u8 icmp_type)
{
  switch (icmp_type)
    {
    case ICMP4_echo_request:
    case ICMP4_echo_reply:
      return 1;
    }
  return 0;
}

static_always_inline u8
icmp6_type_is_echo (u8 icmp_type)
{
  switch (icmp_type)
    {
    case ICMP6_echo_request:
    case ICMP6_echo_reply:
      return 1;
    }
  return 0;
}

static_always_inline u8
icmp6_type_is_error_message (u8 icmp_type)
{
  switch (icmp_type)
    {
    case ICMP6_destination_unreachable:
    case ICMP6_time_exceeded:
    case ICMP6_parameter_problem:
      return 1;
    }
  return 0;
}

static_always_inline u8
cmp_ip6_address (const ip6_address_t * a1, const ip6_address_t * a2)
{
  return ((a1->as_u64[0] == a2->as_u64[0])
	  && (a1->as_u64[1] == a2->as_u64[1]));
}

/**
 * Inline translation functions
 */

static_always_inline u8
has_ip6_address (ip6_address_t * a)
{
  return ((0 != a->as_u64[0]) || (0 != a->as_u64[1]));
}

static_always_inline void
cnat_ip4_translate_l4 (ip4_header_t * ip4, udp_header_t * udp,
		       ip_csum_t * sum,
		       ip4_address_t new_addr[VLIB_N_DIR],
		       u16 new_port[VLIB_N_DIR])
{
  u16 old_port[VLIB_N_DIR];
  ip4_address_t old_addr[VLIB_N_DIR];

  /* Fastpath no checksum */
  if (PREDICT_TRUE (0 == *sum))
    {
      udp->dst_port = new_port[VLIB_TX];
      udp->src_port = new_port[VLIB_RX];
      return;
    }

  old_port[VLIB_TX] = udp->dst_port;
  old_port[VLIB_RX] = udp->src_port;
  old_addr[VLIB_TX] = ip4->dst_address;
  old_addr[VLIB_RX] = ip4->src_address;

  if (new_addr[VLIB_TX].as_u32)
    {
      *sum =
	ip_csum_update (*sum, old_addr[VLIB_TX].as_u32,
			new_addr[VLIB_TX].as_u32, ip4_header_t, dst_address);
    }
  if (new_port[VLIB_TX])
    {
      udp->dst_port = new_port[VLIB_TX];
      *sum = ip_csum_update (*sum, old_port[VLIB_TX], new_port[VLIB_TX],
			     ip4_header_t /* cheat */ ,
			     length /* changed member */ );
    }
  if (new_addr[VLIB_RX].as_u32)
    {
      *sum =
	ip_csum_update (*sum, old_addr[VLIB_RX].as_u32,
			new_addr[VLIB_RX].as_u32, ip4_header_t, src_address);
    }
  if (new_port[VLIB_RX])
    {
      udp->src_port = new_port[VLIB_RX];
      *sum = ip_csum_update (*sum, old_port[VLIB_RX], new_port[VLIB_RX],
			     ip4_header_t /* cheat */ ,
			     length /* changed member */ );
    }
}

static_always_inline void
cnat_ip4_translate_l3 (ip4_header_t * ip4, ip4_address_t new_addr[VLIB_N_DIR])
{
  ip4_address_t old_addr[VLIB_N_DIR];
  ip_csum_t sum;

  old_addr[VLIB_TX] = ip4->dst_address;
  old_addr[VLIB_RX] = ip4->src_address;

  sum = ip4->checksum;
  if (new_addr[VLIB_TX].as_u32)
    {
      ip4->dst_address = new_addr[VLIB_TX];
      sum =
	ip_csum_update (sum, old_addr[VLIB_TX].as_u32,
			new_addr[VLIB_TX].as_u32, ip4_header_t, dst_address);
    }
  if (new_addr[VLIB_RX].as_u32)
    {
      ip4->src_address = new_addr[VLIB_RX];
      sum =
	ip_csum_update (sum, old_addr[VLIB_RX].as_u32,
			new_addr[VLIB_RX].as_u32, ip4_header_t, src_address);
    }
  ip4->checksum = ip_csum_fold (sum);
}

static_always_inline void
cnat_tcp_update_session_lifetime (tcp_header_t * tcp, u32 index)
{
  cnat_main_t *cm = &cnat_main;
  if (PREDICT_FALSE (tcp_fin (tcp)))
    {
      cnat_timestamp_set_lifetime (index, CNAT_DEFAULT_TCP_RST_TIMEOUT);
    }

  if (PREDICT_FALSE (tcp_rst (tcp)))
    {
      cnat_timestamp_set_lifetime (index, CNAT_DEFAULT_TCP_RST_TIMEOUT);
    }

  if (PREDICT_FALSE (tcp_syn (tcp) && tcp_ack (tcp)))
    {
      cnat_timestamp_set_lifetime (index, cm->tcp_max_age);
    }
}

static_always_inline void
cnat_translation_icmp4_echo (ip4_header_t * ip4, icmp46_header_t * icmp,
			     ip4_address_t new_addr[VLIB_N_DIR],
			     u16 new_port[VLIB_N_DIR])
{
  ip_csum_t sum;
  u16 old_port;
  cnat_echo_header_t *echo = (cnat_echo_header_t *) (icmp + 1);

  cnat_ip4_translate_l3 (ip4, new_addr);
  old_port = echo->identifier;
  echo->identifier = new_port[VLIB_RX];

  sum = icmp->checksum;
  sum = ip_csum_update (sum, old_port, new_port[VLIB_RX],
			ip4_header_t /* cheat */ ,
			length /* changed member */ );

  icmp->checksum = ip_csum_fold (sum);
}

static_always_inline void
cnat_translation_icmp4_error (ip4_header_t * outer_ip4,
			      icmp46_header_t * icmp,
			      ip4_address_t outer_new_addr[VLIB_N_DIR],
			      u16 outer_new_port[VLIB_N_DIR],
			      u8 snat_outer_ip)
{
  ip4_address_t new_addr[VLIB_N_DIR];
  ip4_address_t old_addr[VLIB_N_DIR];
  u16 new_port[VLIB_N_DIR];
  u16 old_port[VLIB_N_DIR];
  ip_csum_t sum, old_ip_sum, inner_l4_sum, inner_l4_old_sum;

  ip4_header_t *ip4 = (ip4_header_t *) (icmp + 2);
  udp_header_t *udp = (udp_header_t *) (ip4 + 1);
  tcp_header_t *tcp = (tcp_header_t *) udp;

  /* Swap inner ports */
  new_addr[VLIB_TX] = outer_new_addr[VLIB_RX];
  new_addr[VLIB_RX] = outer_new_addr[VLIB_TX];
  new_port[VLIB_TX] = outer_new_port[VLIB_RX];
  new_port[VLIB_RX] = outer_new_port[VLIB_TX];

  old_addr[VLIB_TX] = ip4->dst_address;
  old_addr[VLIB_RX] = ip4->src_address;
  old_port[VLIB_RX] = udp->src_port;
  old_port[VLIB_TX] = udp->dst_port;

  sum = icmp->checksum;
  old_ip_sum = ip4->checksum;

  /* translate outer ip. */
  if (!snat_outer_ip)
    outer_new_addr[VLIB_RX] = outer_ip4->src_address;
  cnat_ip4_translate_l3 (outer_ip4, outer_new_addr);

  if (ip4->protocol == IP_PROTOCOL_TCP)
    {
      inner_l4_old_sum = inner_l4_sum = tcp->checksum;
      cnat_ip4_translate_l4 (ip4, udp, &inner_l4_sum, new_addr, new_port);
      tcp->checksum = ip_csum_fold (inner_l4_sum);
    }
  else if (ip4->protocol == IP_PROTOCOL_UDP)
    {
      inner_l4_old_sum = inner_l4_sum = udp->checksum;
      cnat_ip4_translate_l4 (ip4, udp, &inner_l4_sum, new_addr, new_port);
      udp->checksum = ip_csum_fold (inner_l4_sum);
    }
  else
    return;

  /* UDP/TCP checksum changed */
  sum = ip_csum_update (sum, inner_l4_old_sum, inner_l4_sum,
			ip4_header_t, checksum);

  /* UDP/TCP Ports changed */
  if (old_port[VLIB_TX] && new_port[VLIB_TX])
    sum = ip_csum_update (sum, old_port[VLIB_TX], new_port[VLIB_TX],
			  ip4_header_t /* cheat */ ,
			  length /* changed member */ );

  if (old_port[VLIB_RX] && new_port[VLIB_RX])
    sum = ip_csum_update (sum, old_port[VLIB_RX], new_port[VLIB_RX],
			  ip4_header_t /* cheat */ ,
			  length /* changed member */ );


  cnat_ip4_translate_l3 (ip4, new_addr);
  ip_csum_t new_ip_sum = ip4->checksum;
  /* IP checksum changed */
  sum = ip_csum_update (sum, old_ip_sum, new_ip_sum, ip4_header_t, checksum);

  /* IP src/dst addr changed */
  if (new_addr[VLIB_TX].as_u32)
    sum =
      ip_csum_update (sum, old_addr[VLIB_TX].as_u32, new_addr[VLIB_TX].as_u32,
		      ip4_header_t, dst_address);

  if (new_addr[VLIB_RX].as_u32)
    sum =
      ip_csum_update (sum, old_addr[VLIB_RX].as_u32, new_addr[VLIB_RX].as_u32,
		      ip4_header_t, src_address);

  icmp->checksum = ip_csum_fold (sum);
}

static_always_inline void
cnat_translation_ip4 (const cnat_session_t * session,
		      ip4_header_t * ip4, udp_header_t * udp)
{
  tcp_header_t *tcp = (tcp_header_t *) udp;
  ip4_address_t new_addr[VLIB_N_DIR];
  u16 new_port[VLIB_N_DIR];

  new_addr[VLIB_TX] = session->value.cs_ip[VLIB_TX].ip4;
  new_addr[VLIB_RX] = session->value.cs_ip[VLIB_RX].ip4;
  new_port[VLIB_TX] = session->value.cs_port[VLIB_TX];
  new_port[VLIB_RX] = session->value.cs_port[VLIB_RX];

  if (ip4->protocol == IP_PROTOCOL_TCP)
    {
      ip_csum_t sum = tcp->checksum;
      cnat_ip4_translate_l4 (ip4, udp, &sum, new_addr, new_port);
      tcp->checksum = ip_csum_fold (sum);
      cnat_ip4_translate_l3 (ip4, new_addr);
      cnat_tcp_update_session_lifetime (tcp, session->value.cs_ts_index);
    }
  else if (ip4->protocol == IP_PROTOCOL_UDP)
    {
      ip_csum_t sum = udp->checksum;
      cnat_ip4_translate_l4 (ip4, udp, &sum, new_addr, new_port);
      udp->checksum = ip_csum_fold (sum);
      cnat_ip4_translate_l3 (ip4, new_addr);
    }
  else if (ip4->protocol == IP_PROTOCOL_ICMP)
    {
      icmp46_header_t *icmp = (icmp46_header_t *) udp;
      if (icmp_type_is_error_message (icmp->type))
	{
	  /* SNAT only if src_addr was translated */
	  u8 snat_outer_ip =
	    (ip4->src_address.as_u32 ==
	     session->key.cs_ip[VLIB_RX].ip4.as_u32);
	  cnat_translation_icmp4_error (ip4, icmp, new_addr, new_port,
					snat_outer_ip);
	}
      else if (icmp_type_is_echo (icmp->type))
	cnat_translation_icmp4_echo (ip4, icmp, new_addr, new_port);
    }
}

static_always_inline void
cnat_ip6_translate_l3 (ip6_header_t * ip6, ip6_address_t new_addr[VLIB_N_DIR])
{
  if (has_ip6_address (&new_addr[VLIB_TX]))
    ip6_address_copy (&ip6->dst_address, &new_addr[VLIB_TX]);
  if (has_ip6_address (&new_addr[VLIB_RX]))
    ip6_address_copy (&ip6->src_address, &new_addr[VLIB_RX]);
}

static_always_inline void
cnat_ip6_translate_l4 (ip6_header_t * ip6, udp_header_t * udp,
		       ip_csum_t * sum,
		       ip6_address_t new_addr[VLIB_N_DIR],
		       u16 new_port[VLIB_N_DIR])
{
  u16 old_port[VLIB_N_DIR];
  ip6_address_t old_addr[VLIB_N_DIR];

  /* Fastpath no checksum */
  if (PREDICT_TRUE (0 == *sum))
    {
      udp->dst_port = new_port[VLIB_TX];
      udp->src_port = new_port[VLIB_RX];
      return;
    }

  old_port[VLIB_TX] = udp->dst_port;
  old_port[VLIB_RX] = udp->src_port;
  ip6_address_copy (&old_addr[VLIB_TX], &ip6->dst_address);
  ip6_address_copy (&old_addr[VLIB_RX], &ip6->src_address);

  if (has_ip6_address (&new_addr[VLIB_TX]))
    {
      *sum = ip_csum_add_even (*sum, new_addr[VLIB_TX].as_u64[0]);
      *sum = ip_csum_add_even (*sum, new_addr[VLIB_TX].as_u64[1]);
      *sum = ip_csum_sub_even (*sum, old_addr[VLIB_TX].as_u64[0]);
      *sum = ip_csum_sub_even (*sum, old_addr[VLIB_TX].as_u64[1]);
    }

  if (new_port[VLIB_TX])
    {
      udp->dst_port = new_port[VLIB_TX];
      *sum = ip_csum_update (*sum, old_port[VLIB_TX], new_port[VLIB_TX],
			     ip4_header_t /* cheat */ ,
			     length /* changed member */ );
    }
  if (has_ip6_address (&new_addr[VLIB_RX]))
    {
      *sum = ip_csum_add_even (*sum, new_addr[VLIB_RX].as_u64[0]);
      *sum = ip_csum_add_even (*sum, new_addr[VLIB_RX].as_u64[1]);
      *sum = ip_csum_sub_even (*sum, old_addr[VLIB_RX].as_u64[0]);
      *sum = ip_csum_sub_even (*sum, old_addr[VLIB_RX].as_u64[1]);
    }

  if (new_port[VLIB_RX])
    {
      udp->src_port = new_port[VLIB_RX];
      *sum = ip_csum_update (*sum, old_port[VLIB_RX], new_port[VLIB_RX],
			     ip4_header_t /* cheat */ ,
			     length /* changed member */ );
    }
}

static_always_inline void
cnat_translation_icmp6_echo (ip6_header_t * ip6, icmp46_header_t * icmp,
			     ip6_address_t new_addr[VLIB_N_DIR],
			     u16 new_port[VLIB_N_DIR])
{
  cnat_echo_header_t *echo = (cnat_echo_header_t *) (icmp + 1);
  ip6_address_t old_addr[VLIB_N_DIR];
  ip_csum_t sum;
  u16 old_port;
  old_port = echo->identifier;
  ip6_address_copy (&old_addr[VLIB_TX], &ip6->dst_address);
  ip6_address_copy (&old_addr[VLIB_RX], &ip6->src_address);

  sum = icmp->checksum;

  cnat_ip6_translate_l3 (ip6, new_addr);
  if (has_ip6_address (&new_addr[VLIB_TX]))
    {
      sum = ip_csum_add_even (sum, new_addr[VLIB_TX].as_u64[0]);
      sum = ip_csum_add_even (sum, new_addr[VLIB_TX].as_u64[1]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_TX].as_u64[0]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_TX].as_u64[1]);
    }

  if (has_ip6_address (&new_addr[VLIB_RX]))
    {
      sum = ip_csum_add_even (sum, new_addr[VLIB_RX].as_u64[0]);
      sum = ip_csum_add_even (sum, new_addr[VLIB_RX].as_u64[1]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_RX].as_u64[0]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_RX].as_u64[1]);
    }

  echo->identifier = new_port[VLIB_RX];
  sum = ip_csum_update (sum, old_port, new_port[VLIB_RX],
			ip4_header_t /* cheat */ ,
			length /* changed member */ );

  icmp->checksum = ip_csum_fold (sum);
}

static_always_inline void
cnat_translation_icmp6_error (ip6_header_t * outer_ip6,
			      icmp46_header_t * icmp,
			      ip6_address_t outer_new_addr[VLIB_N_DIR],
			      u16 outer_new_port[VLIB_N_DIR],
			      u8 snat_outer_ip)
{
  ip6_address_t new_addr[VLIB_N_DIR];
  ip6_address_t old_addr[VLIB_N_DIR];
  ip6_address_t outer_old_addr[VLIB_N_DIR];
  u16 new_port[VLIB_N_DIR];
  u16 old_port[VLIB_N_DIR];
  ip_csum_t sum, inner_l4_sum, inner_l4_old_sum;

  if (!icmp6_type_is_error_message (icmp->type))
    return;

  ip6_header_t *ip6 = (ip6_header_t *) (icmp + 2);
  udp_header_t *udp = (udp_header_t *) (ip6 + 1);
  tcp_header_t *tcp = (tcp_header_t *) udp;

  /* Swap inner ports */
  ip6_address_copy (&new_addr[VLIB_RX], &outer_new_addr[VLIB_TX]);
  ip6_address_copy (&new_addr[VLIB_TX], &outer_new_addr[VLIB_RX]);
  new_port[VLIB_TX] = outer_new_port[VLIB_RX];
  new_port[VLIB_RX] = outer_new_port[VLIB_TX];

  ip6_address_copy (&old_addr[VLIB_TX], &ip6->dst_address);
  ip6_address_copy (&old_addr[VLIB_RX], &ip6->src_address);
  old_port[VLIB_RX] = udp->src_port;
  old_port[VLIB_TX] = udp->dst_port;

  sum = icmp->checksum;
  /* Translate outer ip */
  ip6_address_copy (&outer_old_addr[VLIB_TX], &outer_ip6->dst_address);
  ip6_address_copy (&outer_old_addr[VLIB_RX], &outer_ip6->src_address);
  if (!snat_outer_ip)
    ip6_address_copy (&outer_new_addr[VLIB_RX], &outer_ip6->src_address);
  cnat_ip6_translate_l3 (outer_ip6, outer_new_addr);
  if (has_ip6_address (&outer_new_addr[VLIB_TX]))
    {
      sum = ip_csum_add_even (sum, outer_new_addr[VLIB_TX].as_u64[0]);
      sum = ip_csum_add_even (sum, outer_new_addr[VLIB_TX].as_u64[1]);
      sum = ip_csum_sub_even (sum, outer_old_addr[VLIB_TX].as_u64[0]);
      sum = ip_csum_sub_even (sum, outer_old_addr[VLIB_TX].as_u64[1]);
    }

  if (has_ip6_address (&outer_new_addr[VLIB_RX]))
    {
      sum = ip_csum_add_even (sum, outer_new_addr[VLIB_RX].as_u64[0]);
      sum = ip_csum_add_even (sum, outer_new_addr[VLIB_RX].as_u64[1]);
      sum = ip_csum_sub_even (sum, outer_old_addr[VLIB_RX].as_u64[0]);
      sum = ip_csum_sub_even (sum, outer_old_addr[VLIB_RX].as_u64[1]);
    }

  /* Translate inner TCP / UDP */
  if (ip6->protocol == IP_PROTOCOL_TCP)
    {
      inner_l4_old_sum = inner_l4_sum = tcp->checksum;
      cnat_ip6_translate_l4 (ip6, udp, &inner_l4_sum, new_addr, new_port);
      tcp->checksum = ip_csum_fold (inner_l4_sum);
    }
  else if (ip6->protocol == IP_PROTOCOL_UDP)
    {
      inner_l4_old_sum = inner_l4_sum = udp->checksum;
      cnat_ip6_translate_l4 (ip6, udp, &inner_l4_sum, new_addr, new_port);
      udp->checksum = ip_csum_fold (inner_l4_sum);
    }
  else
    return;

  /* UDP/TCP checksum changed */
  sum = ip_csum_update (sum, inner_l4_old_sum, inner_l4_sum,
			ip4_header_t /* cheat */ ,
			checksum);

  /* UDP/TCP Ports changed */
  if (old_port[VLIB_TX] && new_port[VLIB_TX])
    sum = ip_csum_update (sum, old_port[VLIB_TX], new_port[VLIB_TX],
			  ip4_header_t /* cheat */ ,
			  length /* changed member */ );

  if (old_port[VLIB_RX] && new_port[VLIB_RX])
    sum = ip_csum_update (sum, old_port[VLIB_RX], new_port[VLIB_RX],
			  ip4_header_t /* cheat */ ,
			  length /* changed member */ );


  cnat_ip6_translate_l3 (ip6, new_addr);
  /* IP src/dst addr changed */
  if (has_ip6_address (&new_addr[VLIB_TX]))
    {
      sum = ip_csum_add_even (sum, new_addr[VLIB_TX].as_u64[0]);
      sum = ip_csum_add_even (sum, new_addr[VLIB_TX].as_u64[1]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_TX].as_u64[0]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_TX].as_u64[1]);
    }

  if (has_ip6_address (&new_addr[VLIB_RX]))
    {
      sum = ip_csum_add_even (sum, new_addr[VLIB_RX].as_u64[0]);
      sum = ip_csum_add_even (sum, new_addr[VLIB_RX].as_u64[1]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_RX].as_u64[0]);
      sum = ip_csum_sub_even (sum, old_addr[VLIB_RX].as_u64[1]);
    }

  icmp->checksum = ip_csum_fold (sum);
}

static_always_inline void
cnat_translation_ip6 (const cnat_session_t * session,
		      ip6_header_t * ip6, udp_header_t * udp)
{
  tcp_header_t *tcp = (tcp_header_t *) udp;
  ip6_address_t new_addr[VLIB_N_DIR];
  u16 new_port[VLIB_N_DIR];

  ip6_address_copy (&new_addr[VLIB_TX], &session->value.cs_ip[VLIB_TX].ip6);
  ip6_address_copy (&new_addr[VLIB_RX], &session->value.cs_ip[VLIB_RX].ip6);
  new_port[VLIB_TX] = session->value.cs_port[VLIB_TX];
  new_port[VLIB_RX] = session->value.cs_port[VLIB_RX];

  if (ip6->protocol == IP_PROTOCOL_TCP)
    {
      ip_csum_t sum = tcp->checksum;
      cnat_ip6_translate_l4 (ip6, udp, &sum, new_addr, new_port);
      tcp->checksum = ip_csum_fold (sum);
      cnat_ip6_translate_l3 (ip6, new_addr);
      cnat_tcp_update_session_lifetime (tcp, session->value.cs_ts_index);
    }
  else if (ip6->protocol == IP_PROTOCOL_UDP)
    {
      ip_csum_t sum = udp->checksum;
      cnat_ip6_translate_l4 (ip6, udp, &sum, new_addr, new_port);
      udp->checksum = ip_csum_fold (sum);
      cnat_ip6_translate_l3 (ip6, new_addr);
    }
  else if (ip6->protocol == IP_PROTOCOL_ICMP6)
    {
      icmp46_header_t *icmp = (icmp46_header_t *) udp;
      if (icmp6_type_is_error_message (icmp->type))
	{
	  /* SNAT only if src_addr was translated */
	  u8 snat_outer_ip = cmp_ip6_address (&ip6->src_address,
					      &session->key.
					      cs_ip[VLIB_RX].ip6);
	  cnat_translation_icmp6_error (ip6, icmp, new_addr, new_port,
					snat_outer_ip);
	}
      else if (icmp6_type_is_echo (icmp->type))
	cnat_translation_icmp6_echo (ip6, icmp, new_addr, new_port);
    }
}

static_always_inline void
cnat_session_make_key (vlib_buffer_t *b, ip_address_family_t af,
		       cnat_session_location_t cs_loc, cnat_bihash_kv_t *bkey)
{
  udp_header_t *udp;
  cnat_session_t *session = (cnat_session_t *) bkey;
  u32 iph_offset = 0;
  session->key.cs_af = af;

  session->key.cs_loc = cs_loc;
  session->key.__cs_pad = 0;
  if (cs_loc == CNAT_LOCATION_OUTPUT)
    /* rewind buffer */
    iph_offset = vnet_buffer (b)->ip.save_rewrite_length;

  if (AF_IP4 == af)
    {
      ip4_header_t *ip4;
      ip4 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b) + iph_offset);

      if (PREDICT_FALSE (ip4->protocol == IP_PROTOCOL_ICMP))
	{
	  icmp46_header_t *icmp = (icmp46_header_t *) (ip4 + 1);
	  if (icmp_type_is_error_message (icmp->type))
	    {
	      ip4 = (ip4_header_t *) (icmp + 2);	/* Use inner packet */
	      udp = (udp_header_t *) (ip4 + 1);
	      /* Swap dst & src for search as ICMP payload is reversed */
	      ip46_address_set_ip4 (&session->key.cs_ip[VLIB_RX],
				    &ip4->dst_address);
	      ip46_address_set_ip4 (&session->key.cs_ip[VLIB_TX],
				    &ip4->src_address);
	      session->key.cs_proto = ip4->protocol;
	      session->key.cs_port[VLIB_TX] = udp->src_port;
	      session->key.cs_port[VLIB_RX] = udp->dst_port;
	    }
	  else if (icmp_type_is_echo (icmp->type))
	    {
	      cnat_echo_header_t *echo = (cnat_echo_header_t *) (icmp + 1);
	      ip46_address_set_ip4 (&session->key.cs_ip[VLIB_TX],
				    &ip4->dst_address);
	      ip46_address_set_ip4 (&session->key.cs_ip[VLIB_RX],
				    &ip4->src_address);
	      session->key.cs_proto = ip4->protocol;
	      session->key.cs_port[VLIB_TX] = echo->identifier;
	      session->key.cs_port[VLIB_RX] = echo->identifier;
	    }
	  else
	    goto error;
	}
      else if (ip4->protocol == IP_PROTOCOL_UDP ||
	       ip4->protocol == IP_PROTOCOL_TCP)
	{
	  udp = (udp_header_t *) (ip4 + 1);
	  ip46_address_set_ip4 (&session->key.cs_ip[VLIB_TX],
				&ip4->dst_address);
	  ip46_address_set_ip4 (&session->key.cs_ip[VLIB_RX],
				&ip4->src_address);
	  session->key.cs_proto = ip4->protocol;
	  session->key.cs_port[VLIB_RX] = udp->src_port;
	  session->key.cs_port[VLIB_TX] = udp->dst_port;
	}
      else
	goto error;
    }
  else
    {
      ip6_header_t *ip6;
      ip6 = (ip6_header_t *) ((u8 *) vlib_buffer_get_current (b) + iph_offset);
      if (PREDICT_FALSE (ip6->protocol == IP_PROTOCOL_ICMP6))
	{
	  icmp46_header_t *icmp = (icmp46_header_t *) (ip6 + 1);
	  if (icmp6_type_is_error_message (icmp->type))
	    {
	      ip6 = (ip6_header_t *) (icmp + 2);	/* Use inner packet */
	      udp = (udp_header_t *) (ip6 + 1);
	      /* Swap dst & src for search as ICMP payload is reversed */
	      ip46_address_set_ip6 (&session->key.cs_ip[VLIB_RX],
				    &ip6->dst_address);
	      ip46_address_set_ip6 (&session->key.cs_ip[VLIB_TX],
				    &ip6->src_address);
	      session->key.cs_proto = ip6->protocol;
	      session->key.cs_port[VLIB_TX] = udp->src_port;
	      session->key.cs_port[VLIB_RX] = udp->dst_port;
	    }
	  else if (icmp6_type_is_echo (icmp->type))
	    {
	      cnat_echo_header_t *echo = (cnat_echo_header_t *) (icmp + 1);
	      ip46_address_set_ip6 (&session->key.cs_ip[VLIB_TX],
				    &ip6->dst_address);
	      ip46_address_set_ip6 (&session->key.cs_ip[VLIB_RX],
				    &ip6->src_address);
	      session->key.cs_proto = ip6->protocol;
	      session->key.cs_port[VLIB_TX] = echo->identifier;
	      session->key.cs_port[VLIB_RX] = echo->identifier;
	    }
	  else
	    goto error;
	}
      else if (ip6->protocol == IP_PROTOCOL_UDP ||
	       ip6->protocol == IP_PROTOCOL_TCP)
	{
	  udp = (udp_header_t *) (ip6 + 1);
	  ip46_address_set_ip6 (&session->key.cs_ip[VLIB_TX],
				&ip6->dst_address);
	  ip46_address_set_ip6 (&session->key.cs_ip[VLIB_RX],
				&ip6->src_address);
	  session->key.cs_port[VLIB_RX] = udp->src_port;
	  session->key.cs_port[VLIB_TX] = udp->dst_port;
	  session->key.cs_proto = ip6->protocol;
	}
      else
	goto error;
    }
  return;

error:
  /* Ensure we dont find anything */
  session->key.cs_proto = 0;
  return;
}

static_always_inline cnat_ep_trk_t *
cnat_load_balance (const cnat_translation_t *ct, ip_address_family_t af,
		   ip4_header_t *ip4, ip6_header_t *ip6, u32 *dpoi_index)
{
  cnat_main_t *cm = &cnat_main;
  const load_balance_t *lb0;
  const dpo_id_t *dpo0;
  u32 hash_c0, bucket0;

  lb0 = load_balance_get (ct->ct_lb.dpoi_index);
  if (PREDICT_FALSE (!lb0->lb_n_buckets))
    return (NULL);

  /* session table miss */
  hash_c0 = (AF_IP4 == af ? ip4_compute_flow_hash (ip4, lb0->lb_hash_config) :
			    ip6_compute_flow_hash (ip6, lb0->lb_hash_config));

  if (PREDICT_FALSE (ct->lb_type == CNAT_LB_MAGLEV))
    bucket0 = ct->lb_maglev[hash_c0 % cm->maglev_len];
  else
    bucket0 = hash_c0 % lb0->lb_n_buckets;

  dpo0 = load_balance_get_fwd_bucket (lb0, bucket0);

  *dpoi_index = dpo0->dpoi_index;

  return &ct->ct_active_paths[bucket0];
}

/**
 * Create NAT sessions
 * rsession_location is the location the (return) session will be
 * matched at
 */
static_always_inline void
cnat_session_create (cnat_session_t *session, cnat_node_ctx_t *ctx,
		     cnat_session_location_t rsession_location,
		     u8 rsession_flags)
{
  cnat_client_t *cc;
  cnat_bihash_kv_t rkey;
  cnat_session_t *rsession = (cnat_session_t *) & rkey;
  cnat_bihash_kv_t *bkey = (cnat_bihash_kv_t *) session;
  cnat_bihash_kv_t rvalue;
  int rv;

  session->value.cs_ts_index = cnat_timestamp_new (ctx->now);
  cnat_bihash_add_del (&cnat_session_db, bkey, 1);

  if (!(rsession_flags & CNAT_SESSION_FLAG_NO_CLIENT))
    {
      /* is this the first time we've seen this source address */
      cc = (AF_IP4 == ctx->af ?
	      cnat_client_ip4_find (&session->value.cs_ip[VLIB_RX].ip4) :
	      cnat_client_ip6_find (&session->value.cs_ip[VLIB_RX].ip6));

      if (NULL == cc)
	{
	  ip_address_t addr;
	  uword *p;
	  u32 refcnt;

	  addr.version = ctx->af;
	  ip46_address_copy (&addr.ip, &session->value.cs_ip[VLIB_RX]);

	  /* Throttle */
	  clib_spinlock_lock (&cnat_client_db.throttle_lock);

	  p = hash_get_mem (cnat_client_db.throttle_mem, &addr);
	  if (p)
	    {
	      refcnt = p[0] + 1;
	      hash_set_mem (cnat_client_db.throttle_mem, &addr, refcnt);
	    }
	  else
	    hash_set_mem_alloc (&cnat_client_db.throttle_mem, &addr, 0);

	  clib_spinlock_unlock (&cnat_client_db.throttle_lock);

	  /* fire client create to the main thread */
	  if (!p)
	    vl_api_rpc_call_main_thread (cnat_client_learn, (u8 *) &addr,
					 sizeof (addr));
	}
      else
	{
	  /* Refcount reverse session */
	  cnat_client_cnt_session (cc);
	}
    }

  /* create the reverse flow key */
  ip46_address_copy (&rsession->key.cs_ip[VLIB_RX],
		     &session->value.cs_ip[VLIB_TX]);
  ip46_address_copy (&rsession->key.cs_ip[VLIB_TX],
		     &session->value.cs_ip[VLIB_RX]);
  rsession->key.cs_proto = session->key.cs_proto;
  rsession->key.cs_loc = rsession_location;
  rsession->key.__cs_pad = 0;
  rsession->key.cs_af = ctx->af;
  rsession->key.cs_port[VLIB_RX] = session->value.cs_port[VLIB_TX];
  rsession->key.cs_port[VLIB_TX] = session->value.cs_port[VLIB_RX];

  /* First search for existing reverse session */
  rv = cnat_bihash_search_i2 (&cnat_session_db, &rkey, &rvalue);
  if (!rv)
    {
      /* Reverse session already exists
         cleanup before creating for refcnts */
      cnat_session_t *found_rsession = (cnat_session_t *) & rvalue;
      cnat_session_free (found_rsession);
    }
  /* add the reverse flow */
  ip46_address_copy (&rsession->value.cs_ip[VLIB_RX],
		     &session->key.cs_ip[VLIB_TX]);
  ip46_address_copy (&rsession->value.cs_ip[VLIB_TX],
		     &session->key.cs_ip[VLIB_RX]);
  rsession->value.cs_ts_index = session->value.cs_ts_index;
  rsession->value.cs_lbi = INDEX_INVALID;
  rsession->value.flags = rsession_flags;
  rsession->value.cs_port[VLIB_TX] = session->key.cs_port[VLIB_RX];
  rsession->value.cs_port[VLIB_RX] = session->key.cs_port[VLIB_TX];

  cnat_bihash_add_del (&cnat_session_db, &rkey, 1);
}

always_inline uword
cnat_node_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
		  vlib_frame_t *frame, cnat_node_sub_t cnat_sub,
		  ip_address_family_t af, cnat_session_location_t cs_loc,
		  u8 do_trace)
{
  u32 n_left, *from, thread_index;
  vlib_buffer_t *bufs[VLIB_FRAME_SIZE];
  vlib_buffer_t **b = bufs;
  u16 nexts[VLIB_FRAME_SIZE], *next;
  f64 now;

  thread_index = vm->thread_index;
  from = vlib_frame_vector_args (frame);
  n_left = frame->n_vectors;
  next = nexts;
  vlib_get_buffers (vm, from, bufs, n_left);
  now = vlib_time_now (vm);
  cnat_session_t *session[4];
  cnat_bihash_kv_t bkey[4], bvalue[4];
  u64 hash[4];
  int rv[4];

  cnat_node_ctx_t ctx = { now, thread_index, af, do_trace };

  if (n_left >= 8)
    {
      /* Kickstart our state */
      cnat_session_make_key (b[3], af, cs_loc, &bkey[3]);
      cnat_session_make_key (b[2], af, cs_loc, &bkey[2]);
      cnat_session_make_key (b[1], af, cs_loc, &bkey[1]);
      cnat_session_make_key (b[0], af, cs_loc, &bkey[0]);

      hash[3] = cnat_bihash_hash (&bkey[3]);
      hash[2] = cnat_bihash_hash (&bkey[2]);
      hash[1] = cnat_bihash_hash (&bkey[1]);
      hash[0] = cnat_bihash_hash (&bkey[0]);
    }

  while (n_left >= 8)
    {
      if (n_left >= 12)
	{
	  vlib_prefetch_buffer_header (b[11], LOAD);
	  vlib_prefetch_buffer_header (b[10], LOAD);
	  vlib_prefetch_buffer_header (b[9], LOAD);
	  vlib_prefetch_buffer_header (b[8], LOAD);
	}

      rv[3] = cnat_bihash_search_i2_hash (&cnat_session_db, hash[3], &bkey[3],
					  &bvalue[3]);
      session[3] = (cnat_session_t *) (rv[3] ? &bkey[3] : &bvalue[3]);
      next[3] = cnat_sub (vm, node, b[3], &ctx, rv[3], session[3]);

      rv[2] = cnat_bihash_search_i2_hash (&cnat_session_db, hash[2], &bkey[2],
					  &bvalue[2]);
      session[2] = (cnat_session_t *) (rv[2] ? &bkey[2] : &bvalue[2]);
      next[2] = cnat_sub (vm, node, b[2], &ctx, rv[2], session[2]);

      rv[1] = cnat_bihash_search_i2_hash (&cnat_session_db, hash[1], &bkey[1],
					  &bvalue[1]);
      session[1] = (cnat_session_t *) (rv[1] ? &bkey[1] : &bvalue[1]);
      next[1] = cnat_sub (vm, node, b[1], &ctx, rv[1], session[1]);

      rv[0] = cnat_bihash_search_i2_hash (&cnat_session_db, hash[0], &bkey[0],
					  &bvalue[0]);
      session[0] = (cnat_session_t *) (rv[0] ? &bkey[0] : &bvalue[0]);
      next[0] = cnat_sub (vm, node, b[0], &ctx, rv[0], session[0]);

      cnat_session_make_key (b[7], af, cs_loc, &bkey[3]);
      cnat_session_make_key (b[6], af, cs_loc, &bkey[2]);
      cnat_session_make_key (b[5], af, cs_loc, &bkey[1]);
      cnat_session_make_key (b[4], af, cs_loc, &bkey[0]);

      hash[3] = cnat_bihash_hash (&bkey[3]);
      hash[2] = cnat_bihash_hash (&bkey[2]);
      hash[1] = cnat_bihash_hash (&bkey[1]);
      hash[0] = cnat_bihash_hash (&bkey[0]);

      cnat_bihash_prefetch_bucket (&cnat_session_db, hash[3]);
      cnat_bihash_prefetch_bucket (&cnat_session_db, hash[2]);
      cnat_bihash_prefetch_bucket (&cnat_session_db, hash[1]);
      cnat_bihash_prefetch_bucket (&cnat_session_db, hash[0]);

      cnat_bihash_prefetch_data (&cnat_session_db, hash[3]);
      cnat_bihash_prefetch_data (&cnat_session_db, hash[2]);
      cnat_bihash_prefetch_data (&cnat_session_db, hash[1]);
      cnat_bihash_prefetch_data (&cnat_session_db, hash[0]);

      b += 4;
      next += 4;
      n_left -= 4;
    }

  while (n_left > 0)
    {
      cnat_session_make_key (b[0], af, cs_loc, &bkey[0]);
      rv[0] = cnat_bihash_search_i2 (&cnat_session_db, &bkey[0], &bvalue[0]);

      session[0] = (cnat_session_t *) (rv[0] ? &bkey[0] : &bvalue[0]);
      next[0] = cnat_sub (vm, node, b[0], &ctx, rv[0], session[0]);

      b++;
      next++;
      n_left--;
    }

  vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);

  return frame->n_vectors;
}

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */

#endif