nat.h

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/*
 * 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 proto:8,
          fib_index:24;
      u16 l_port;
      u16 r_port;
    };
    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;


#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
#define SNAT_SESSION_FLAG_TWICE_NAT      8

#define NAT_INTERFACE_FLAG_IS_INSIDE 1
#define NAT_INTERFACE_FLAG_IS_OUTSIDE 2

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 and port */
  ip4_address_t ext_host_addr;  /* 68-71 */
  u16 ext_host_port;            /* 72-73 */

  /* External hos address and port after translation */
  ip4_address_t ext_host_nat_addr; /* 74-77 */
  u16 ext_host_nat_port;           /* 78-79 */
}) 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;
  u8 twice_nat;
  u32 vrf_id;
  u32 fib_index;
  snat_protocol_t proto;
  u32 worker_index;
  nat44_lb_addr_port_t *locals;
} snat_static_mapping_t;

typedef struct {
  u32 sw_if_index;
  u8 flags;
} 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 twice_nat;
  int is_add;
} snat_static_map_resolve_t;

typedef struct {
  /* Main lookup tables */
  clib_bihash_8_8_t out2in;
  clib_bihash_8_8_t in2out;

  /* Find-a-user => src address lookup */
  clib_bihash_8_8_t user_hash;

  /* 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,
                                        ip4_header_t *ip0,
                                        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 int nat_alloc_out_addr_and_port_function_t (snat_address_t * addresses,
                                                    u32 fib_index,
                                                    u32 thread_index,
                                                    snat_session_key_t * k,
                                                    u32 * address_indexp,
                                                    u16 port_per_thread,
                                                    u32 snat_thread_index);

typedef struct snat_main_s {
  /* Endpoint address dependent sessions lookup tables */
  clib_bihash_16_8_t out2in_ed;
  clib_bihash_16_8_t in2out_ed;

  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;
  nat_alloc_out_addr_and_port_function_t *alloc_addr_and_port;
  u8 psid_offset;
  u8 psid_length;
  u16 psid;

  /* Vector of twice NAT addresses for extenal 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 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;

  /* If forwarding is enabled */
  u8 forwarding_enabled;

  /* Config parameters */
  u8 static_mapping_only;
  u8 static_mapping_connection_tracking;
  u8 deterministic;
  u32 translation_buckets;
  u32 translation_memory_size;
  u32 max_translations;
  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;

  /* 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_address_t * addresses,
                                         u32 thread_index,
                                         snat_session_key_t * k,
                                         u32 address_index);

int snat_alloc_outside_address_and_port (snat_address_t * addresses,
                                         u32 fib_index,
                                         u32 thread_index,
                                         snat_session_key_t * k,
                                         u32 * address_indexp,
                                         u16 port_per_thread,
                                         u32 snat_thread_index);

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,
                               u8 *twice_nat);

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)

/** \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 endpoint dependent.
    @param s NAT session
    @return 1 if NAT session is endpoint dependent
*/
#define is_ed_session(s) (snat_is_unk_proto_session (s) || is_twice_nat_session (s) || is_lb_session (s))

#define nat_interface_is_inside(i) i->flags & NAT_INTERFACE_FLAG_IS_INSIDE
#define nat_interface_is_outside(i) i->flags & NAT_INTERFACE_FLAG_IS_OUTSIDE

/*
 * 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,
                           ip4_header_t *ip0, 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,
                           ip4_header_t *ip0, 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,
                          ip4_header_t *ip0, 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,
                           ip4_header_t *ip0, 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,
                           ip4_header_t *ip0, 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,
                          ip4_header_t *ip0, 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,
                      u8 twice_nat);
int snat_del_address(snat_main_t *sm, ip4_address_t addr, u8 delete_sm,
                     u8 twice_nat);
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,
                            u8 twice_nat);
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,
                               u8 twice_nat);
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,
                                     u8 twice_nat);
int nat44_del_session (snat_main_t *sm, ip4_address_t *addr, u16 port,
                       snat_protocol_t proto, u32 vrf_id, int is_in);
void nat_free_session_data (snat_main_t * sm, snat_session_t * s,
                            u32 thread_index);
snat_user_t * nat_user_get_or_create (snat_main_t *sm, ip4_address_t *addr,
                                      u32 fib_index, u32 thread_index);
snat_session_t * nat_session_alloc_or_recycle (snat_main_t *sm, snat_user_t *u,
                                               u32 thread_index);

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;
}

always_inline u8
maximum_sessions_exceeded (snat_main_t *sm, u32 thread_index)
{
  if (pool_elts (sm->per_thread_data[thread_index].sessions) >= sm->max_translations)
    return 1;

  return 0;
}

static_always_inline void
nat_send_all_to_node(vlib_main_t *vm, u32 *bi_vector,
                     vlib_node_runtime_t *node, vlib_error_t *error, u32 next)
{
  u32 n_left_from, *from, next_index, *to_next, n_left_to_next;

  from = bi_vector;
  n_left_from = vec_len(bi_vector);
  next_index = node->cached_next_index;
  while (n_left_from > 0) {
    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 = to_next[0] = from[0];
      from += 1;
      n_left_from -= 1;
      to_next += 1;
      n_left_to_next -= 1;
      vlib_buffer_t *p0 = vlib_get_buffer(vm, bi0);
      p0->error = *error;
      vlib_validate_buffer_enqueue_x1(vm, node, next_index, to_next,
                                      n_left_to_next, bi0, next);
    }
    vlib_put_next_frame(vm, node, next_index, n_left_to_next);
  }
}

always_inline void
user_session_increment(snat_main_t *sm, snat_user_t *u, u8 is_static)
{
  if (u->nsessions + u->nstaticsessions < sm->max_translations_per_user)
    {
      if (is_static)
        u->nstaticsessions++;
      else
        u->nsessions++;
    }
}

#endif /* __included_snat_h__ */