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, 1183 insertions, 0 deletions

diff --git a/src/plugins/nat/nat44-ed/nat44_ed.h b/src/plugins/nat/nat44-ed/nat44_ed.h
new file mode 100644
index 00000000000..10d1207fec8
--- /dev/null
+++ b/src/plugins/nat/nat44-ed/nat44_ed.h
@@ -0,0 +1,1183 @@
+/*
+ * 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.
+ */
+/**
+ * @file nat.c
+ * NAT plugin global declarations
+ */
+#ifndef __included_nat44_ed_h__
+#define __included_nat44_ed_h__
+
+#include <vnet/vnet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/ip/icmp46_packet.h>
+#include <vnet/api_errno.h>
+#include <vnet/fib/fib_source.h>
+#include <vppinfra/elog.h>
+#include <vppinfra/bihash_8_8.h>
+#include <vppinfra/bihash_16_8.h>
+#include <vppinfra/dlist.h>
+#include <vppinfra/error.h>
+#include <vlibapi/api.h>
+
+#include <nat/lib/lib.h>
+#include <nat/lib/inlines.h>
+
+/* default number of worker handoff frame queue elements */
+#define NAT_FQ_NELTS_DEFAULT 64
+
+/* NAT buffer flags */
+#define SNAT_FLAG_HAIRPINNING (1 << 0)
+
+/* NAT44 API Configuration flags */
+#define foreach_nat44_config_flag  \
+  _(0x00, IS_ENDPOINT_INDEPENDENT) \
+  _(0x01, IS_ENDPOINT_DEPENDENT)   \
+  _(0x02, IS_STATIC_MAPPING_ONLY)  \
+  _(0x04, IS_CONNECTION_TRACKING)  \
+  _(0x08, IS_OUT2IN_DPO)
+
+typedef enum nat44_config_flags_t_
+{
+#define _(n,f) NAT44_API_##f = n,
+  foreach_nat44_config_flag
+#undef _
+} nat44_config_flags_t;
+
+typedef struct
+{
+  /* nat44 plugin features */
+  u8 static_mapping_only;
+  u8 connection_tracking;
+
+  u32 inside_vrf;
+  u32 outside_vrf;
+
+  /* maximum number of sessions */
+  u32 sessions;
+
+} nat44_config_t;
+
+typedef enum
+{
+  NAT_NEXT_DROP,
+  NAT_NEXT_ICMP_ERROR,
+  NAT_NEXT_IN2OUT_ED_FAST_PATH,
+  NAT_NEXT_IN2OUT_ED_SLOW_PATH,
+  NAT_NEXT_IN2OUT_ED_OUTPUT_FAST_PATH,
+  NAT_NEXT_IN2OUT_ED_OUTPUT_SLOW_PATH,
+  NAT_NEXT_OUT2IN_ED_FAST_PATH,
+  NAT_NEXT_OUT2IN_ED_SLOW_PATH,
+  NAT_NEXT_IN2OUT_CLASSIFY,
+  NAT_NEXT_OUT2IN_CLASSIFY,
+  NAT_N_NEXT,
+} nat_next_t;
+
+typedef struct
+{
+  u32 next_index;
+  u32 arc_next_index;
+} nat_pre_trace_t;
+
+/* External address and port allocation modes */
+#define foreach_nat_addr_and_port_alloc_alg \
+  _(0, DEFAULT, "default")         \
+  _(1, MAPE, "map-e")              \
+  _(2, RANGE, "port-range")
+
+typedef enum
+{
+#define _(v, N, s) NAT_ADDR_AND_PORT_ALLOC_ALG_##N = v,
+  foreach_nat_addr_and_port_alloc_alg
+#undef _
+} nat_addr_and_port_alloc_alg_t;
+
+/* Session state */
+#define foreach_snat_session_state          \
+  _(0, UNKNOWN, "unknown")                 \
+  _(1, UDP_ACTIVE, "udp-active")           \
+  _(2, TCP_SYN_SENT, "tcp-syn-sent")       \
+  _(3, TCP_ESTABLISHED, "tcp-established") \
+  _(4, TCP_FIN_WAIT, "tcp-fin-wait")       \
+  _(5, TCP_CLOSE_WAIT, "tcp-close-wait")   \
+  _(6, TCP_CLOSING, "tcp-closing")         \
+  _(7, TCP_LAST_ACK, "tcp-last-ack")       \
+  _(8, TCP_CLOSED, "tcp-closed")           \
+  _(9, ICMP_ACTIVE, "icmp-active")
+
+typedef enum
+{
+#define _(v, N, s) SNAT_SESSION_##N = v,
+  foreach_snat_session_state
+#undef _
+} snat_session_state_t;
+
+#define foreach_nat_in2out_ed_error                     \
+_(UNSUPPORTED_PROTOCOL, "unsupported protocol")         \
+_(OUT_OF_PORTS, "out of ports")                         \
+_(BAD_ICMP_TYPE, "unsupported ICMP type")               \
+_(MAX_SESSIONS_EXCEEDED, "maximum sessions exceeded")   \
+_(NON_SYN, "non-SYN packet try to create session")      \
+_(TCP_CLOSED, "drops due to TCP in transitory timeout")
+
+typedef enum
+{
+#define _(sym,str) NAT_IN2OUT_ED_ERROR_##sym,
+  foreach_nat_in2out_ed_error
+#undef _
+    NAT_IN2OUT_ED_N_ERROR,
+} nat_in2out_ed_error_t;
+
+#define foreach_nat_out2in_ed_error                                           \
+  _ (UNSUPPORTED_PROTOCOL, "unsupported protocol")                            \
+  _ (OUT_OF_PORTS, "out of ports")                                            \
+  _ (BAD_ICMP_TYPE, "unsupported ICMP type")                                  \
+  _ (NO_TRANSLATION, "no translation")                                        \
+  _ (MAX_SESSIONS_EXCEEDED, "maximum sessions exceeded")                      \
+  _ (NON_SYN, "non-SYN packet try to create session")                         \
+  _ (TCP_CLOSED, "drops due to TCP in transitory timeout")                    \
+  _ (HASH_ADD_FAILED, "hash table add failed")
+
+typedef enum
+{
+#define _(sym,str) NAT_OUT2IN_ED_ERROR_##sym,
+  foreach_nat_out2in_ed_error
+#undef _
+    NAT_OUT2IN_ED_N_ERROR,
+} nat_out2in_ed_error_t;
+
+
+/* Endpoint dependent TCP session state */
+#define NAT44_SES_I2O_FIN 1
+#define NAT44_SES_O2I_FIN 2
+#define NAT44_SES_I2O_FIN_ACK 4
+#define NAT44_SES_O2I_FIN_ACK 8
+#define NAT44_SES_I2O_SYN 16
+#define NAT44_SES_O2I_SYN 32
+#define NAT44_SES_RST     64
+
+/* Session flags */
+#define SNAT_SESSION_FLAG_STATIC_MAPPING     (1 << 0)
+#define SNAT_SESSION_FLAG_UNKNOWN_PROTO	     (1 << 1)
+#define SNAT_SESSION_FLAG_LOAD_BALANCING     (1 << 2)
+#define SNAT_SESSION_FLAG_TWICE_NAT	     (1 << 3)
+#define SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT (1 << 4)
+#define SNAT_SESSION_FLAG_FWD_BYPASS	     (1 << 5)
+#define SNAT_SESSION_FLAG_AFFINITY	     (1 << 6)
+#define SNAT_SESSION_FLAG_EXACT_ADDRESS	     (1 << 7)
+#define SNAT_SESSION_FLAG_HAIRPINNING	     (1 << 8)
+
+/* NAT interface flags */
+#define NAT_INTERFACE_FLAG_IS_INSIDE 1
+#define NAT_INTERFACE_FLAG_IS_OUTSIDE 2
+
+/* Static mapping flags */
+#define NAT_STATIC_MAPPING_FLAG_ADDR_ONLY      1
+#define NAT_STATIC_MAPPING_FLAG_OUT2IN_ONLY    2
+#define NAT_STATIC_MAPPING_FLAG_IDENTITY_NAT   4
+#define NAT_STATIC_MAPPING_FLAG_LB             8
+#define NAT_STATIC_MAPPING_FLAG_EXACT_ADDRESS  16
+
+/* *INDENT-OFF* */
+typedef CLIB_PACKED(struct
+{
+  // number of sessions in this vrf
+  u32 ses_count;
+
+  u32 rx_fib_index;
+  u32 tx_fib_index;
+
+  // is this vrf expired
+  u8 expired;
+}) per_vrf_sessions_t;
+/* *INDENT-ON* */
+
+typedef struct
+{
+  ip4_address_t saddr, daddr;
+  u32 fib_index;
+  u16 sport, dport;
+  u16 icmp_id;
+  u8 proto;
+} nat_6t_t;
+
+typedef struct
+{
+#define NAT_FLOW_OP_SADDR_REWRITE   (1 << 1)
+#define NAT_FLOW_OP_SPORT_REWRITE   (1 << 2)
+#define NAT_FLOW_OP_DADDR_REWRITE   (1 << 3)
+#define NAT_FLOW_OP_DPORT_REWRITE   (1 << 4)
+#define NAT_FLOW_OP_ICMP_ID_REWRITE (1 << 5)
+#define NAT_FLOW_OP_TXFIB_REWRITE   (1 << 6)
+  int ops;
+  nat_6t_t match;
+  nat_6t_t rewrite;
+  uword l3_csum_delta;
+  uword l4_csum_delta;
+} nat_6t_flow_t;
+
+void nat44_ed_forwarding_enable_disable (u8 is_enable);
+
+always_inline void
+nat_6t_flow_saddr_rewrite_set (nat_6t_flow_t *f, u32 saddr)
+{
+  f->ops |= NAT_FLOW_OP_SADDR_REWRITE;
+  f->rewrite.saddr.as_u32 = saddr;
+}
+
+always_inline void
+nat_6t_flow_daddr_rewrite_set (nat_6t_flow_t *f, u32 daddr)
+{
+  f->ops |= NAT_FLOW_OP_DADDR_REWRITE;
+  f->rewrite.daddr.as_u32 = daddr;
+}
+
+always_inline void
+nat_6t_flow_sport_rewrite_set (nat_6t_flow_t *f, u32 sport)
+{
+  f->ops |= NAT_FLOW_OP_SPORT_REWRITE;
+  f->rewrite.sport = sport;
+}
+
+always_inline void
+nat_6t_flow_dport_rewrite_set (nat_6t_flow_t *f, u32 dport)
+{
+  f->ops |= NAT_FLOW_OP_DPORT_REWRITE;
+  f->rewrite.dport = dport;
+}
+
+always_inline void
+nat_6t_flow_txfib_rewrite_set (nat_6t_flow_t *f, u32 tx_fib_index)
+{
+  f->ops |= NAT_FLOW_OP_TXFIB_REWRITE;
+  f->rewrite.fib_index = tx_fib_index;
+}
+
+always_inline void
+nat_6t_flow_icmp_id_rewrite_set (nat_6t_flow_t *f, u16 id)
+{
+  f->ops |= NAT_FLOW_OP_ICMP_ID_REWRITE;
+  f->rewrite.icmp_id = id;
+}
+
+/* *INDENT-OFF* */
+typedef CLIB_PACKED(struct
+{
+  /* Outside network tuple */
+  struct
+  {
+    ip4_address_t addr;
+    u32 fib_index;
+    u16 port;
+  } out2in;
+
+  /* Inside network tuple */
+  struct
+  {
+    ip4_address_t addr;
+    u32 fib_index;
+    u16 port;
+  } in2out;
+
+  nat_protocol_t nat_proto;
+
+  nat_6t_flow_t i2o;
+  nat_6t_flow_t o2i;
+
+  /* Flags */
+  u32 flags;
+
+  /* head of LRU list in which this session is tracked */
+  u32 lru_head_index;
+  /* index in global LRU list */
+  u32 lru_index;
+  f64 last_lru_update;
+
+  /* Last heard timer */
+  f64 last_heard;
+
+  /* Last HA refresh */
+  f64 ha_last_refreshed;
+
+  /* Counters */
+  u64 total_bytes;
+  u32 total_pkts;
+
+  /* External host address and port */
+  ip4_address_t ext_host_addr;
+  u16 ext_host_port;
+
+  /* External host address and port after translation */
+  ip4_address_t ext_host_nat_addr;
+  u16 ext_host_nat_port;
+
+  /* TCP session state */
+  u8 state;
+  u32 i2o_fin_seq;
+  u32 o2i_fin_seq;
+  u64 tcp_closed_timestamp;
+
+  /* per vrf sessions index */
+  u32 per_vrf_sessions_index;
+
+}) snat_session_t;
+/* *INDENT-ON* */
+
+typedef struct
+{
+  ip4_address_t addr;
+  u32 fib_index;
+/* *INDENT-OFF* */
+#define _(N, i, n, s) \
+  u32 busy_##n##_ports; \
+  u32 * busy_##n##_ports_per_thread; \
+  u32 busy_##n##_port_refcounts[65535];
+  foreach_nat_protocol
+#undef _
+/* *INDENT-ON* */
+} snat_address_t;
+
+typedef struct
+{
+  u32 fib_index;
+  u32 ref_count;
+} nat_fib_t;
+
+typedef struct
+{
+  u32 fib_index;
+  u32 refcount;
+} nat_outside_fib_t;
+
+typedef struct
+{
+  /* backend IP address */
+  ip4_address_t addr;
+  /* backend port number */
+  u16 port;
+  /* probability of the backend to be randomly matched */
+  u8 probability;
+  u8 prefix;
+  /* backend FIB table */
+  u32 vrf_id;
+  u32 fib_index;
+} nat44_lb_addr_port_t;
+
+typedef enum
+{
+  /* twice-nat disabled */
+  TWICE_NAT_DISABLED,
+  /* twice-nat enabled */
+  TWICE_NAT,
+  /* twice-nat only when src IP equals dst IP after translation */
+  TWICE_NAT_SELF,
+} twice_nat_type_t;
+
+typedef enum
+{
+  /* no load-balancing */
+  NO_LB_NAT,
+  /* load-balancing */
+  LB_NAT,
+  /* load-balancing with affinity */
+  AFFINITY_LB_NAT,
+} lb_nat_type_t;
+
+typedef struct
+{
+  /* prefered pool address */
+  ip4_address_t pool_addr;
+  /* local IP address */
+  ip4_address_t local_addr;
+  /* external IP address */
+  ip4_address_t external_addr;
+  /* local port */
+  u16 local_port;
+  /* external port */
+  u16 external_port;
+  /* is twice-nat */
+  twice_nat_type_t twice_nat;
+  /* local FIB table */
+  u32 vrf_id;
+  u32 fib_index;
+  /* protocol */
+  nat_protocol_t proto;
+  /* 0 = disabled, otherwise client IP affinity sticky time in seconds */
+  u32 affinity;
+  /* worker threads used by backends/local host */
+  u32 *workers;
+  /* opaque string tag */
+  u8 *tag;
+  /* backends for load-balancing mode */
+  nat44_lb_addr_port_t *locals;
+  /* affinity per service lis */
+  u32 affinity_per_service_list_head_index;
+  /* flags */
+  u32 flags;
+} snat_static_mapping_t;
+
+typedef struct
+{
+  u32 sw_if_index;
+  u8 flags;
+} snat_interface_t;
+
+typedef struct
+{
+  ip4_address_t l_addr;
+  ip4_address_t pool_addr;
+  u16 l_port;
+  u16 e_port;
+  u32 sw_if_index;
+  u32 vrf_id;
+  nat_protocol_t proto;
+  u32 flags;
+  int addr_only;
+  int twice_nat;
+  int out2in_only;
+  int identity_nat;
+  int exact;
+  u8 *tag;
+} snat_static_map_resolve_t;
+
+typedef struct
+{
+  /* Session pool */
+  snat_session_t *sessions;
+
+  /* Pool of doubly-linked list elements */
+  dlist_elt_t *list_pool;
+
+  /* LRU session list - head is stale, tail is fresh */
+  dlist_elt_t *lru_pool;
+  u32 tcp_trans_lru_head_index;
+  u32 tcp_estab_lru_head_index;
+  u32 udp_lru_head_index;
+  u32 icmp_lru_head_index;
+  u32 unk_proto_lru_head_index;
+
+  /* NAT thread index */
+  u32 snat_thread_index;
+
+  /* real thread index */
+  u32 thread_index;
+
+  per_vrf_sessions_t *per_vrf_sessions_vec;
+
+} snat_main_per_thread_data_t;
+
+struct snat_main_s;
+
+/* Return worker thread index for given packet */
+typedef u32 (snat_get_worker_in2out_function_t) (ip4_header_t * ip,
+						 u32 rx_fib_index,
+						 u8 is_output);
+
+typedef u32 (snat_get_worker_out2in_function_t) (vlib_buffer_t * b,
+						 ip4_header_t * ip,
+						 u32 rx_fib_index,
+						 u8 is_output);
+
+/* NAT address and port allocation function */
+typedef int (nat_alloc_out_addr_and_port_function_t) (snat_address_t *
+						      addresses,
+						      u32 fib_index,
+						      u32 thread_index,
+						      nat_protocol_t proto,
+						      ip4_address_t * addr,
+						      u16 * port,
+						      u16 port_per_thread,
+						      u32 snat_thread_index);
+
+typedef struct snat_main_s
+{
+  /* Thread settings */
+  u32 num_workers;
+  u32 first_worker_index;
+  u32 *workers;
+  snat_get_worker_in2out_function_t *worker_in2out_cb;
+  snat_get_worker_out2in_function_t *worker_out2in_cb;
+  u16 port_per_thread;
+
+  /* Per thread data */
+  snat_main_per_thread_data_t *per_thread_data;
+
+  /* Find a static mapping by local */
+  clib_bihash_8_8_t static_mapping_by_local;
+
+  /* Find a static mapping by external */
+  clib_bihash_8_8_t static_mapping_by_external;
+
+  /* Static mapping pool */
+  snat_static_mapping_t *static_mappings;
+
+  /* Endpoint independent lookup tables */
+  clib_bihash_8_8_t in2out;
+  clib_bihash_8_8_t out2in;
+
+  /* Endpoint dependent lookup table */
+  clib_bihash_16_8_t flow_hash;
+
+  /* Interface pool */
+  snat_interface_t *interfaces;
+  snat_interface_t *output_feature_interfaces;
+
+  /* Vector of outside addresses */
+  snat_address_t *addresses;
+  /* Address and port allocation function */
+  nat_alloc_out_addr_and_port_function_t *alloc_addr_and_port;
+  /* Address and port allocation type */
+  nat_addr_and_port_alloc_alg_t addr_and_port_alloc_alg;
+  /* Port set parameters (MAP-E) */
+  u8 psid_offset;
+  u8 psid_length;
+  u16 psid;
+  /* Port range parameters */
+  u16 start_port;
+  u16 end_port;
+
+  /* vector of fibs */
+  nat_fib_t *fibs;
+
+  /* vector of outside fibs */
+  nat_outside_fib_t *outside_fibs;
+
+  /* Vector of twice NAT addresses for external hosts */
+  snat_address_t *twice_nat_addresses;
+
+  /* sw_if_indices whose intfc addresses should be auto-added */
+  u32 *auto_add_sw_if_indices;
+  u32 *auto_add_sw_if_indices_twice_nat;
+
+  /* vector of interface address static mappings to resolve. */
+  snat_static_map_resolve_t *to_resolve;
+
+  /* Randomize port allocation order */
+  u32 random_seed;
+
+  /* Worker handoff frame-queue index */
+  u32 fq_in2out_index;
+  u32 fq_in2out_output_index;
+  u32 fq_out2in_index;
+
+  u32 out2in_node_index;
+  u32 in2out_node_index;
+  u32 in2out_output_node_index;
+
+  nat44_config_t rconfig;
+  //nat44_config_t cconfig;
+
+  /* If forwarding is enabled */
+  u8 forwarding_enabled;
+
+  /* static mapping config */
+  u8 static_mapping_only;
+  u8 static_mapping_connection_tracking;
+
+  /* Is translation memory size calculated or user defined */
+  u8 translation_memory_size_set;
+
+  u32 translation_buckets;
+  u32 max_translations_per_thread;
+  u32 *max_translations_per_fib;
+
+  u32 outside_vrf_id;
+  u32 outside_fib_index;
+  u32 inside_vrf_id;
+  u32 inside_fib_index;
+
+  nat_timeouts_t timeouts;
+
+  /* TCP MSS clamping */
+  u16 mss_clamping;
+
+  /* counters */
+  vlib_simple_counter_main_t total_sessions;
+
+#define _(x) vlib_simple_counter_main_t x;
+  struct
+  {
+    struct
+    {
+      struct
+      {
+	foreach_nat_counter;
+      } in2out;
+
+      struct
+      {
+	foreach_nat_counter;
+      } out2in;
+    } fastpath;
+
+    struct
+    {
+      struct
+      {
+	foreach_nat_counter;
+      } in2out;
+
+      struct
+      {
+	foreach_nat_counter;
+      } out2in;
+    } slowpath;
+
+    vlib_simple_counter_main_t hairpinning;
+  } counters;
+#undef _
+
+  /* API message ID base */
+  u16 msg_id_base;
+
+  /* log class */
+  vlib_log_class_t log_class;
+  /* logging level */
+  u8 log_level;
+
+  /* convenience */
+  api_main_t *api_main;
+  ip4_main_t *ip4_main;
+  ip_lookup_main_t *ip4_lookup_main;
+
+  fib_source_t fib_src_hi;
+  fib_source_t fib_src_low;
+
+  /* pat - dynamic mapping enabled or conneciton tracking */
+  u8 pat;
+
+  /* number of worker handoff frame queue elements */
+  u32 frame_queue_nelts;
+
+  /* nat44 plugin enabled */
+  u8 enabled;
+
+  vnet_main_t *vnet_main;
+
+} snat_main_t;
+
+typedef struct
+{
+  u32 thread_index;
+  f64 now;
+} nat44_is_idle_session_ctx_t;
+
+typedef struct
+{
+  u32 cached_sw_if_index;
+  u32 cached_ip4_address;
+} snat_runtime_t;
+
+extern snat_main_t snat_main;
+
+// nat pre ed next_node feature classification
+extern vlib_node_registration_t nat_default_node;
+extern vlib_node_registration_t nat_pre_in2out_node;
+extern vlib_node_registration_t nat_pre_out2in_node;
+
+extern vlib_node_registration_t snat_in2out_node;
+extern vlib_node_registration_t snat_in2out_output_node;
+extern vlib_node_registration_t snat_out2in_node;
+extern vlib_node_registration_t snat_in2out_worker_handoff_node;
+extern vlib_node_registration_t snat_in2out_output_worker_handoff_node;
+extern vlib_node_registration_t snat_out2in_worker_handoff_node;
+extern vlib_node_registration_t nat44_ed_in2out_node;
+extern vlib_node_registration_t nat44_ed_in2out_output_node;
+extern vlib_node_registration_t nat44_ed_out2in_node;
+
+extern fib_source_t nat_fib_src_hi;
+extern fib_source_t nat_fib_src_low;
+
+/* format functions */
+format_function_t format_snat_static_mapping;
+format_function_t format_snat_static_map_to_resolve;
+format_function_t format_snat_session;
+format_function_t format_snat_key;
+format_function_t format_static_mapping_key;
+format_function_t format_nat_protocol;
+format_function_t format_nat_addr_and_port_alloc_alg;
+/* unformat functions */
+unformat_function_t unformat_nat_protocol;
+
+/** \brief Check if SNAT session is created from static mapping.
+    @param s SNAT session
+    @return 1 if SNAT session is created from static mapping otherwise 0
+*/
+#define snat_is_session_static(s) (s->flags & SNAT_SESSION_FLAG_STATIC_MAPPING)
+
+/** \brief Check if SNAT session for unknown protocol.
+    @param s SNAT session
+    @return 1 if SNAT session for unknown protocol otherwise 0
+*/
+#define snat_is_unk_proto_session(s) (s->flags & SNAT_SESSION_FLAG_UNKNOWN_PROTO)
+
+/** \brief Check if NAT session is twice NAT.
+    @param s NAT session
+    @return 1 if NAT session is twice NAT
+*/
+#define is_twice_nat_session(s) (s->flags & SNAT_SESSION_FLAG_TWICE_NAT)
+
+/** \brief Check if NAT session is load-balancing.
+    @param s NAT session
+    @return 1 if NAT session is load-balancing
+*/
+#define is_lb_session(s) (s->flags & SNAT_SESSION_FLAG_LOAD_BALANCING)
+
+/** \brief Check if NAT session is forwarding bypass.
+    @param s NAT session
+    @return 1 if NAT session is load-balancing
+*/
+#define is_fwd_bypass_session(s) (s->flags & SNAT_SESSION_FLAG_FWD_BYPASS)
+
+/** \brief Check if NAT session is endpoint dependent.
+    @param s NAT session
+    @return 1 if NAT session is endpoint dependent
+*/
+#define is_ed_session(s) (s->flags & SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT)
+
+/** \brief Check if NAT session has affinity record.
+    @param s NAT session
+    @return 1 if NAT session has affinity record
+*/
+#define is_affinity_sessions(s) (s->flags & SNAT_SESSION_FLAG_AFFINITY)
+
+/** \brief Check if exact pool address should be used.
+    @param s SNAT session
+    @return 1 if exact pool address or 0
+*/
+#define is_exact_address_session(s) (s->flags & SNAT_SESSION_FLAG_EXACT_ADDRESS)
+
+/** \brief Check if NAT interface is inside.
+    @param i NAT interface
+    @return 1 if inside interface
+*/
+#define nat_interface_is_inside(i) i->flags & NAT_INTERFACE_FLAG_IS_INSIDE
+
+/** \brief Check if NAT interface is outside.
+    @param i NAT interface
+    @return 1 if outside interface
+*/
+#define nat_interface_is_outside(i) i->flags & NAT_INTERFACE_FLAG_IS_OUTSIDE
+
+/** \brief Check if NAT44 endpoint-dependent TCP session is closed.
+    @param s NAT session
+    @return 1 if session is closed
+*/
+#define nat44_is_ses_closed(s) s->state == 0xf
+
+/** \brief Check if NAT static mapping is address only (1:1NAT).
+    @param sm NAT static mapping
+    @return 1 if 1:1NAT, 0 if 1:1NAPT
+*/
+#define is_addr_only_static_mapping(sm) (sm->flags & NAT_STATIC_MAPPING_FLAG_ADDR_ONLY)
+
+/** \brief Check if NAT static mapping match only out2in direction.
+    @param sm NAT static mapping
+    @return 1 if rule match only out2in direction
+*/
+#define is_out2in_only_static_mapping(sm) (sm->flags & NAT_STATIC_MAPPING_FLAG_OUT2IN_ONLY)
+
+/** \brief Check if NAT static mapping is identity NAT.
+    @param sm NAT static mapping
+    @return 1 if identity NAT
+*/
+#define is_identity_static_mapping(sm) (sm->flags & NAT_STATIC_MAPPING_FLAG_IDENTITY_NAT)
+
+/** \brief Check if NAT static mapping is load-balancing.
+    @param sm NAT static mapping
+    @return 1 if load-balancing
+*/
+#define is_lb_static_mapping(sm) (sm->flags & NAT_STATIC_MAPPING_FLAG_LB)
+
+/** \brief Check if exact pool address should be used.
+    @param s SNAT session
+    @return 1 if exact pool address or 0
+*/
+#define is_exact_address(s) (s->flags & NAT_STATIC_MAPPING_FLAG_EXACT_ADDRESS)
+
+/** \brief Check if client initiating TCP connection (received SYN from client)
+    @param t TCP header
+    @return 1 if client initiating TCP connection
+*/
+always_inline bool
+tcp_flags_is_init (u8 f)
+{
+  return (f & TCP_FLAG_SYN) && !(f & TCP_FLAG_ACK);
+}
+
+/* logging */
+#define nat_log_err(...) \
+  vlib_log(VLIB_LOG_LEVEL_ERR, snat_main.log_class, __VA_ARGS__)
+#define nat_log_warn(...) \
+  vlib_log(VLIB_LOG_LEVEL_WARNING, snat_main.log_class, __VA_ARGS__)
+#define nat_log_notice(...) \
+  vlib_log(VLIB_LOG_LEVEL_NOTICE, snat_main.log_class, __VA_ARGS__)
+#define nat_log_info(...) \
+  vlib_log(VLIB_LOG_LEVEL_INFO, snat_main.log_class, __VA_ARGS__)
+#define nat_log_debug(...)\
+  vlib_log(VLIB_LOG_LEVEL_DEBUG, snat_main.log_class, __VA_ARGS__)
+
+/**
+ * @brief Enable NAT44 plugin
+ *
+ * @param c         nat44_config_t
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int nat44_plugin_enable (nat44_config_t c);
+
+/**
+ * @brief Disable NAT44 plugin
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int nat44_plugin_disable ();
+
+/**
+ * @brief Add external address to NAT44 pool
+ *
+ * @param sm        snat global configuration data
+ * @param addr      IPv4 address
+ * @param vrf_id    VRF id of tenant, ~0 means independent of VRF
+ * @param twice_nat 1 if twice NAT address
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
+		      u8 twice_nat);
+
+/**
+ * @brief Delete external address from NAT44 pool
+ *
+ * @param sm        snat global configuration data
+ * @param addr      IPv4 address
+ * @param delete_sm 1 if delete static mapping using address
+ * @param twice_nat 1 if twice NAT address
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_del_address (snat_main_t * sm, ip4_address_t addr, u8 delete_sm,
+		      u8 twice_nat);
+
+/**
+ * @brief Add/delete external address to FIB DPO (out2in DPO mode)
+ *
+ * @param addr   IPv4 address
+ * @param is_add 1 = add, 0 = delete
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+void nat44_add_del_address_dpo (ip4_address_t addr, u8 is_add);
+
+/**
+ * @brief Add/delete NAT44 static mapping
+ *
+ * @param l_addr       local IPv4 address
+ * @param e_addr       external IPv4 address
+ * @param l_port       local port number
+ * @param e_port       external port number
+ * @param vrf_id       local VRF ID
+ * @param addr_only    1 = 1:1NAT, 0 = 1:1NAPT
+ * @param sw_if_index  use interface address as external IPv4 address
+ * @param proto        L4 protocol
+ * @param is_add       1 = add, 0 = delete
+ * @param twice_nat    twice-nat mode
+ * @param out2in_only  if 1 rule match only out2in direction
+ * @param tag          opaque string tag
+ * @param identity_nat identity NAT
+ * @param pool_addr    pool IPv4 address
+ * @param exact        1 = exact pool address
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+			     u16 l_port, u16 e_port, u32 vrf_id,
+			     int addr_only, u32 sw_if_index,
+			     nat_protocol_t proto, int is_add,
+			     twice_nat_type_t twice_nat, u8 out2in_only,
+			     u8 * tag, u8 identity_nat,
+			     ip4_address_t pool_addr, int exact);
+
+/**
+ * @brief Add/delete static mapping with load-balancing (multiple backends)
+ *
+ * @param e_addr      external IPv4 address
+ * @param e_port      external port number
+ * @param proto       L4 protocol
+ * @param locals      list of local backends
+ * @param is_add      1 = add, 0 = delete
+ * @param twice_nat   twice-nat mode
+ * @param out2in_only if 1 rule match only out2in direction
+ * @param tag         opaque string tag
+ * @param affinity    0 = disabled, otherwise client IP affinity sticky time
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
+				     nat_protocol_t proto,
+				     nat44_lb_addr_port_t * locals, u8 is_add,
+				     twice_nat_type_t twice_nat,
+				     u8 out2in_only, u8 * tag, u32 affinity);
+
+int nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
+					   ip4_address_t l_addr, u16 l_port,
+					   nat_protocol_t proto, u32 vrf_id,
+					   u8 probability, u8 is_add);
+
+clib_error_t *nat44_api_hookup (vlib_main_t * vm);
+
+/**
+ * @brief Set NAT plugin workers
+ *
+ * @param bitmap NAT workers bitmap
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_set_workers (uword * bitmap);
+
+/**
+ * @brief Set NAT plugin number of frame queue elements
+ *
+ * @param frame_queue_nelts number of worker handoff frame queue elements
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_set_frame_queue_nelts (u32 frame_queue_nelts);
+
+/**
+ * @brief Enable/disable NAT44 feature on the interface
+ *
+ * @param sw_if_index software index of the interface
+ * @param is_inside   1 = inside, 0 = outside
+ * @param is_del      1 = delete, 0 = add
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del);
+
+/**
+ * @brief Enable/disable NAT44 output feature on the interface (postrouting NAT)
+ *
+ * @param sw_if_index software index of the interface
+ * @param is_inside   1 = inside, 0 = outside
+ * @param is_del      1 = delete, 0 = add
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_interface_add_del_output_feature (u32 sw_if_index, u8 is_inside,
+					   int is_del);
+
+/**
+ * @brief Add/delete NAT44 pool address from specific interface
+ *
+ * @param sw_if_index software index of the interface
+ * @param is_del      1 = delete, 0 = add
+ * @param twice_nat   1 = twice NAT address for external hosts
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int snat_add_interface_address (snat_main_t * sm, u32 sw_if_index, int is_del,
+				u8 twice_nat);
+
+/**
+ * @brief Delete NAT44 endpoint-dependent session
+ *
+ * @param sm     snat global configuration data
+ * @param addr   IPv4 address
+ * @param port   L4 port number
+ * @param proto  L4 protocol
+ * @param vrf_id VRF ID
+ * @param is_in  1 = inside network address and port pair, 0 = outside
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int nat44_del_ed_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
+			  ip4_address_t * eh_addr, u16 eh_port, u8 proto,
+			  u32 vrf_id, int is_in);
+
+/**
+ * @brief Free NAT44 session data (lookup keys, external address port)
+ *
+ * @param sm           snat global configuration data
+ * @param s            NAT session
+ * @param thread_index thread index
+ * @param is_ha        is HA event
+ */
+void nat_free_session_data (snat_main_t * sm, snat_session_t * s,
+			    u32 thread_index, u8 is_ha);
+
+/**
+ * @brief Set NAT44 session limit (session limit, vrf id)
+ *
+ * @param session_limit Session limit
+ * @param vrf_id        VRF id
+ * @return 0 on success, non-zero value otherwise
+ */
+int nat44_set_session_limit (u32 session_limit, u32 vrf_id);
+
+/**
+ * @brief Update NAT44 session limit flushing all data (session limit, vrf id)
+ *
+ * @param session_limit Session limit
+ * @param vrf_id        VRF id
+ * @return 0 on success, non-zero value otherwise
+ */
+int nat44_update_session_limit (u32 session_limit, u32 vrf_id);
+
+/**
+ * @brief Free outside address and port pair
+ *
+ * @param addresses    vector of outside addresses
+ * @param thread_index thread index
+ * @param key          address, port and protocol
+ */
+void
+snat_free_outside_address_and_port (snat_address_t * addresses,
+				    u32 thread_index,
+				    ip4_address_t * addr,
+				    u16 port, nat_protocol_t protocol);
+
+void expire_per_vrf_sessions (u32 fib_index);
+
+/**
+ * @brief Match NAT44 static mapping.
+ *
+ * @param key             address and port to match
+ * @param addr            external/local address of the matched mapping
+ * @param port            port of the matched mapping
+ * @param fib_index       fib index of the matched mapping
+ * @param by_external     if 0 match by local address otherwise match by external
+ *                        address
+ * @param is_addr_only    1 if matched mapping is address only
+ * @param twice_nat       matched mapping is twice NAT type
+ * @param lb              1 if matched mapping is load-balanced
+ * @param ext_host_addr   external host address
+ * @param is_identity_nat 1 if indentity mapping
+ * @param out             if !=0 set to pointer of the mapping structure
+ *
+ * @returns 0 if match found otherwise 1.
+ */
+int snat_static_mapping_match (snat_main_t * sm,
+			       ip4_address_t match_addr,
+			       u16 match_port,
+			       u32 match_fib_index,
+			       nat_protocol_t match_protocol,
+			       ip4_address_t * mapping_addr,
+			       u16 * mapping_port,
+			       u32 * mapping_fib_index,
+			       u8 by_external,
+			       u8 * is_addr_only,
+			       twice_nat_type_t * twice_nat,
+			       lb_nat_type_t * lb,
+			       ip4_address_t * ext_host_addr,
+			       u8 * is_identity_nat,
+			       snat_static_mapping_t ** out);
+
+/**
+ * @brief Add/del NAT address to FIB.
+ *
+ * Add the external NAT address to the FIB as receive entries. This ensures
+ * that VPP will reply to ARP for this address and we don't need to enable
+ * proxy ARP on the outside interface.
+ *
+ * @param addr        IPv4 address
+ * @param plen        address prefix length
+ * @param sw_if_index software index of the outside interface
+ * @param is_add      0 = delete, 1 = add.
+ */
+void snat_add_del_addr_to_fib (ip4_address_t * addr,
+			       u8 p_len, u32 sw_if_index, int is_add);
+
+#if 0
+void
+nat_ha_sadd_ed_cb (ip4_address_t * in_addr, u16 in_port,
+		   ip4_address_t * out_addr, u16 out_port,
+		   ip4_address_t * eh_addr, u16 eh_port,
+		   ip4_address_t * ehn_addr, u16 ehn_port, u8 proto,
+		   u32 fib_index, u16 flags, u32 thread_index);
+
+void
+nat_ha_sdel_ed_cb (ip4_address_t * out_addr, u16 out_port,
+		   ip4_address_t * eh_addr, u16 eh_port, u8 proto,
+		   u32 fib_index, u32 ti);
+
+void
+nat_ha_sref_ed_cb (ip4_address_t * out_addr, u16 out_port,
+		   ip4_address_t * eh_addr, u16 eh_port, u8 proto,
+		   u32 fib_index, u32 total_pkts, u64 total_bytes,
+		   u32 thread_index);
+#endif
+
+int nat_set_outside_address_and_port (snat_address_t *addresses,
+				      u32 thread_index, ip4_address_t addr,
+				      u16 port, nat_protocol_t protocol);
+
+/*
+ * Why is this here? Because we don't need to touch this layer to
+ * simply reply to an icmp. We need to change id to a unique
+ * value to NAT an echo request/reply.
+ */
+
+typedef struct
+{
+  u16 identifier;
+  u16 sequence;
+} icmp_echo_header_t;
+
+typedef struct
+{
+  u16 src_port, dst_port;
+} tcp_udp_header_t;
+
+u32 get_thread_idx_by_port (u16 e_port);
+
+u8 *format_static_mapping_kvp (u8 *s, va_list *args);
+
+u8 *format_session_kvp (u8 *s, va_list *args);
+
+u32 nat_calc_bihash_buckets (u32 n_elts);
+
+void nat44_addresses_free (snat_address_t **addresses);
+
+void nat44_ed_sessions_clear ();
+
+int nat44_ed_set_frame_queue_nelts (u32 frame_queue_nelts);
+
+typedef enum
+{
+  NAT_ED_TRNSL_ERR_SUCCESS = 0,
+  NAT_ED_TRNSL_ERR_TRANSLATION_FAILED = 1,
+  NAT_ED_TRNSL_ERR_FLOW_MISMATCH = 2,
+} nat_translation_error_e;
+
+nat_translation_error_e
+nat_6t_flow_buf_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
+			   nat_6t_flow_t *f, nat_protocol_t proto,
+			   int is_output_feature);
+
+void nat_6t_l3_l4_csum_calc (nat_6t_flow_t *f);
+
+format_function_t format_nat_ed_translation_error;
+format_function_t format_nat_6t_flow;
+format_function_t format_ed_session_kvp;
+
+#endif /* __included_nat44_ed_h__ */
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */