text: 
  /*
   * nat.h - NAT plugin definitions
   *
   * Copyright (c) 2016 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 __included_nat_h__
  #define __included_nat_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 <vppinfra/bihash_8_8.h>
  #include <vppinfra/bihash_16_8.h>
  #include <vppinfra/dlist.h>
  #include <vppinfra/error.h>
  #include <vlibapi/api.h>
  
  
  #define SNAT_UDP_TIMEOUT 300
  #define SNAT_UDP_TIMEOUT_MIN 120
  #define SNAT_TCP_TRANSITORY_TIMEOUT 240
  #define SNAT_TCP_ESTABLISHED_TIMEOUT 7440
  #define SNAT_TCP_INCOMING_SYN 6
  #define SNAT_ICMP_TIMEOUT 60
  
  #define SNAT_FLAG_HAIRPINNING (1 << 0)
  
  /* Key */
  typedef struct {
    union
    {
      struct
      {
        ip4_address_t addr;
        u16 port;
        u16 protocol:3,
          fib_index:13;
      };
      u64 as_u64;
    };
  } snat_session_key_t;
  
  typedef struct {
    union
    {
      struct
      {
        ip4_address_t l_addr;
        ip4_address_t r_addr;
        u32 fib_index;
        u16 l_port;
        u8 proto;
        u8 rsvd;
      };
      u64 as_u64[2];
    };
  } nat_ed_ses_key_t;
  
  typedef struct {
    union
    {
      struct
      {
        ip4_address_t ext_host_addr;
        u16 ext_host_port;
        u16 out_port;
      };
      u64 as_u64;
    };
  } snat_det_out_key_t;
  
  typedef struct {
    union
    {
      struct
      {
        ip4_address_t addr;
        u32 fib_index;
      };
      u64 as_u64;
    };
  } snat_user_key_t;
  
  typedef struct {
    union
    {
      struct
      {
        ip4_address_t addr;
        u16 port;
        u16 fib_index;
      };
      u64 as_u64;
    };
  } snat_worker_key_t;
  
  
  #define foreach_snat_protocol \
    _(UDP, 0, udp, "udp")       \
    _(TCP, 1, tcp, "tcp")       \
    _(ICMP, 2, icmp, "icmp")
  
  typedef enum {
  #define _(N, i, n, s) SNAT_PROTOCOL_##N = i,
    foreach_snat_protocol
  #undef _
  } snat_protocol_t;
  
  
  #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_LAST_ACK, "tcp-last-ack")       \
    _(7, ICMP_ACTIVE, "icmp-active")
  
  typedef enum {
  #define _(v, N, s) SNAT_SESSION_##N = v,
    foreach_snat_session_state
  #undef _
  } snat_session_state_t;
  
  
  #define SNAT_SESSION_FLAG_STATIC_MAPPING 1
  #define SNAT_SESSION_FLAG_UNKNOWN_PROTO  2
  #define SNAT_SESSION_FLAG_LOAD_BALANCING 4
  
  typedef CLIB_PACKED(struct {
    snat_session_key_t out2in;    /* 0-15 */
  
    snat_session_key_t in2out;    /* 16-31 */
  
    u32 flags;                    /* 32-35 */
  
    /* per-user translations */
    u32 per_user_index;           /* 36-39 */
  
    u32 per_user_list_head_index; /* 40-43 */
  
    /* Last heard timer */
    f64 last_heard;               /* 44-51 */
  
    u64 total_bytes;              /* 52-59 */
  
    u32 total_pkts;               /* 60-63 */
  
    /* Outside address */
    u32 outside_address_index;    /* 64-67 */
  
    /* External host address */
    ip4_address_t ext_host_addr;  /* 68-71 */
  
  }) snat_session_t;
  
  
  typedef struct {
    ip4_address_t addr;
    u32 fib_index;
    u32 sessions_per_user_list_head_index;
    u32 nsessions;
    u32 nstaticsessions;
  } snat_user_t;
  
  typedef struct {
    ip4_address_t addr;
    u32 fib_index;
  #define _(N, i, n, s) \
    u16 busy_##n##_ports; \
    u16 * busy_##n##_ports_per_thread; \
    uword * busy_##n##_port_bitmap;
    foreach_snat_protocol
  #undef _
  } snat_address_t;
  
  typedef struct {
    u16 in_port;
    snat_det_out_key_t out;
    u8 state;
    u32 expire;
  } snat_det_session_t;
  
  typedef struct {
    ip4_address_t in_addr;
    u8 in_plen;
    ip4_address_t out_addr;
    u8 out_plen;
    u32 sharing_ratio;
    u16 ports_per_host;
    u32 ses_num;
    /* vector of sessions */
    snat_det_session_t * sessions;
  } snat_det_map_t;
  
  typedef struct {
    ip4_address_t addr;
    u16 port;
    u8 probability;
    u8 prefix;
  } nat44_lb_addr_port_t;
  
  typedef struct {
    ip4_address_t local_addr;
    ip4_address_t external_addr;
    u16 local_port;
    u16 external_port;
    u8 addr_only;
    u32 vrf_id;
    u32 fib_index;
    snat_protocol_t proto;
    nat44_lb_addr_port_t *locals;
  } snat_static_mapping_t;
  
  typedef struct {
    u32 sw_if_index;
    u8 is_inside;
  } snat_interface_t;
  
  typedef struct {
    ip4_address_t l_addr;
    u16 l_port;
    u16 e_port;
    u32 sw_if_index;
    u32 vrf_id;
    snat_protocol_t proto;
    int addr_only;
    int is_add;
  } snat_static_map_resolve_t;
  
  typedef struct {
    /* User pool */
    snat_user_t * users;
  
    /* Session pool */
    snat_session_t * sessions;
  
    /* Pool of doubly-linked list elements */
    dlist_elt_t * list_pool;
  
    u32 snat_thread_index;
  } snat_main_per_thread_data_t;
  
  struct snat_main_s;
  
  typedef u32 snat_icmp_match_function_t (struct snat_main_s *sm,
                                          vlib_node_runtime_t *node,
                                          u32 thread_index,
                                          vlib_buffer_t *b0,
                                          u8 *p_proto,
                                          snat_session_key_t *p_value,
                                          u8 *p_dont_translate,
                                          void *d,
                                          void *e);
  
  typedef u32 (snat_get_worker_function_t) (ip4_header_t * ip, u32 rx_fib_index);
  
  typedef struct snat_main_s {
    /* Main lookup tables */
    clib_bihash_8_8_t out2in;
    clib_bihash_8_8_t in2out;
  
    /* Endpoint address dependent sessions lookup tables */
    clib_bihash_16_8_t out2in_ed;
    clib_bihash_16_8_t in2out_ed;
  
    /* Find-a-user => src address lookup */
    clib_bihash_8_8_t user_hash;
  
    /* Non-translated packets worker lookup => src address + VRF */
    clib_bihash_8_8_t worker_by_in;
  
    /* Translated packets worker lookup => IP address + port number */
    clib_bihash_8_8_t worker_by_out;
  
    snat_icmp_match_function_t * icmp_match_in2out_cb;
    snat_icmp_match_function_t * icmp_match_out2in_cb;
  
    u32 num_workers;
    u32 first_worker_index;
    u32 next_worker;
    u32 * workers;
    snat_get_worker_function_t * worker_in2out_cb;
    snat_get_worker_function_t * worker_out2in_cb;
    u16 port_per_thread;
    u32 num_snat_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;
  
    /* Interface pool */
    snat_interface_t * interfaces;
    snat_interface_t * output_feature_interfaces;
  
    /* Vector of outside addresses */
    snat_address_t * addresses;
  
    /* sw_if_indices whose intfc addresses should be auto-added */
    u32 * auto_add_sw_if_indices;
  
    /* vector of interface address static mappings to resolve. */
    snat_static_map_resolve_t *to_resolve;
  
    /* Randomize port allocation order */
    u32 random_seed;
  
    /* Worker handoff index */
    u32 fq_in2out_index;
    u32 fq_in2out_output_index;
    u32 fq_out2in_index;
  
    /* in2out and out2in node index */
    u32 in2out_node_index;
    u32 in2out_output_node_index;
    u32 out2in_node_index;
  
    /* Deterministic NAT */
    snat_det_map_t * det_maps;
  
    /* Config parameters */
    u8 static_mapping_only;
    u8 static_mapping_connection_tracking;
    u8 deterministic;
    u32 translation_buckets;
    u32 translation_memory_size;
    u32 user_buckets;
    u32 user_memory_size;
    u32 max_translations_per_user;
    u32 outside_vrf_id;
    u32 outside_fib_index;
    u32 inside_vrf_id;
    u32 inside_fib_index;
  
    /* tenant VRF aware address pool activation flag */
    u8 vrf_mode;
  
    /* values of various timeouts */
    u32 udp_timeout;
    u32 tcp_established_timeout;
    u32 tcp_transitory_timeout;
    u32 icmp_timeout;
  
    /* API message ID base */
    u16 msg_id_base;
  
    /* convenience */
    vlib_main_t * vlib_main;
    vnet_main_t * vnet_main;
    ip4_main_t * ip4_main;
    ip_lookup_main_t * ip4_lookup_main;
    api_main_t * api_main;
  } snat_main_t;
  
  extern snat_main_t snat_main;
  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_fast_node;
  extern vlib_node_registration_t snat_out2in_fast_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 snat_det_in2out_node;
  extern vlib_node_registration_t snat_det_out2in_node;
  extern vlib_node_registration_t snat_hairpin_dst_node;
  extern vlib_node_registration_t snat_hairpin_src_node;
  
  void snat_free_outside_address_and_port (snat_main_t * sm,
                                           u32 thread_index,
                                           snat_session_key_t * k,
                                           u32 address_index);
  
  int snat_alloc_outside_address_and_port (snat_main_t * sm,
                                           u32 fib_index,
                                           u32 thread_index,
                                           snat_session_key_t * k,
                                           u32 * address_indexp);
  
  int snat_static_mapping_match (snat_main_t * sm,
                                 snat_session_key_t match,
                                 snat_session_key_t * mapping,
                                 u8 by_external,
                                 u8 *is_addr_only);
  
  void snat_add_del_addr_to_fib (ip4_address_t * addr,
                                 u8 p_len,
                                 u32 sw_if_index,
                                 int is_add);
  
  format_function_t format_snat_user;
  
  typedef struct {
    u32 cached_sw_if_index;
    u32 cached_ip4_address;
  } snat_runtime_t;
  
  /** \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
  
  /*
   * 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;
  
  always_inline u32
  ip_proto_to_snat_proto (u8 ip_proto)
  {
    u32 snat_proto = ~0;
  
    snat_proto = (ip_proto == IP_PROTOCOL_UDP) ? SNAT_PROTOCOL_UDP : snat_proto;
    snat_proto = (ip_proto == IP_PROTOCOL_TCP) ? SNAT_PROTOCOL_TCP : snat_proto;
    snat_proto = (ip_proto == IP_PROTOCOL_ICMP) ? SNAT_PROTOCOL_ICMP : snat_proto;
    snat_proto = (ip_proto == IP_PROTOCOL_ICMP6) ? SNAT_PROTOCOL_ICMP : snat_proto;
  
    return snat_proto;
  }
  
  always_inline u8
  snat_proto_to_ip_proto (snat_protocol_t snat_proto)
  {
    u8 ip_proto = ~0;
  
    ip_proto = (snat_proto == SNAT_PROTOCOL_UDP) ? IP_PROTOCOL_UDP : ip_proto;
    ip_proto = (snat_proto == SNAT_PROTOCOL_TCP) ? IP_PROTOCOL_TCP : ip_proto;
    ip_proto = (snat_proto == SNAT_PROTOCOL_ICMP) ? IP_PROTOCOL_ICMP : ip_proto;
  
    return ip_proto;
  }
  
  typedef struct {
    u16 src_port, dst_port;
  } tcp_udp_header_t;
  
  u32 icmp_match_in2out_fast(snat_main_t *sm, vlib_node_runtime_t *node,
                             u32 thread_index, vlib_buffer_t *b0, u8 *p_proto,
                             snat_session_key_t *p_value,
                             u8 *p_dont_translate, void *d, void *e);
  u32 icmp_match_in2out_slow(snat_main_t *sm, vlib_node_runtime_t *node,
                             u32 thread_index, vlib_buffer_t *b0, u8 *p_proto,
                             snat_session_key_t *p_value,
                             u8 *p_dont_translate, void *d, void *e);
  u32 icmp_match_in2out_det(snat_main_t *sm, vlib_node_runtime_t *node,
                            u32 thread_index, vlib_buffer_t *b0, u8 *p_proto,
                            snat_session_key_t *p_value,
                            u8 *p_dont_translate, void *d, void *e);
  u32 icmp_match_out2in_fast(snat_main_t *sm, vlib_node_runtime_t *node,
                             u32 thread_index, vlib_buffer_t *b0, u8 *p_proto,
                             snat_session_key_t *p_value,
                             u8 *p_dont_translate, void *d, void *e);
  u32 icmp_match_out2in_slow(snat_main_t *sm, vlib_node_runtime_t *node,
                             u32 thread_index, vlib_buffer_t *b0, u8 *p_proto,
                             snat_session_key_t *p_value,
                             u8 *p_dont_translate, void *d, void *e);
  u32 icmp_match_out2in_det(snat_main_t *sm, vlib_node_runtime_t *node,
                            u32 thread_index, vlib_buffer_t *b0, u8 *p_proto,
                            snat_session_key_t *p_value,
                            u8 *p_dont_translate, void *d, void *e);
  void increment_v4_address(ip4_address_t * a);
  void snat_add_address(snat_main_t *sm, ip4_address_t *addr, u32 vrf_id);
  int snat_del_address(snat_main_t *sm, ip4_address_t addr, u8 delete_sm);
  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, snat_protocol_t proto, int is_add);
  clib_error_t * snat_api_init(vlib_main_t * vm, snat_main_t * sm);
  int snat_set_workers (uword * bitmap);
  int snat_interface_add_del(u32 sw_if_index, u8 is_inside, int is_del);
  int snat_interface_add_del_output_feature(u32 sw_if_index, u8 is_inside,
                                            int is_del);
  int snat_add_interface_address(snat_main_t *sm, u32 sw_if_index, int is_del);
  uword unformat_snat_protocol(unformat_input_t * input, va_list * args);
  u8 * format_snat_protocol(u8 * s, va_list * args);
  int nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
                                       snat_protocol_t proto, u32 vrf_id,
                                       nat44_lb_addr_port_t *locals, u8 is_add);
  
  static_always_inline u8
  icmp_is_error_message (icmp46_header_t * icmp)
  {
    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
  is_interface_addr(snat_main_t *sm, vlib_node_runtime_t *node, u32 sw_if_index0,
                    u32 ip4_addr)
  {
    snat_runtime_t *rt = (snat_runtime_t *) node->runtime_data;
    ip4_address_t * first_int_addr;
  
    if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index0))
      {
        first_int_addr =
          ip4_interface_first_address (sm->ip4_main, sw_if_index0,
                                       0 /* just want the address */);
        rt->cached_sw_if_index = sw_if_index0;
        if (first_int_addr)
          rt->cached_ip4_address = first_int_addr->as_u32;
        else
          rt->cached_ip4_address = 0;
      }
  
    if (PREDICT_FALSE(ip4_addr == rt->cached_ip4_address))
      return 1;
    else
      return 0;
  }
  
  #endif /* __included_nat_h__ */
  