/*
 * det44.h - deterministic NAT definitions
 *
 * 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
 * @brief Deterministic NAT (CGN) definitions
 */

#ifndef __included_det44_h__
#define __included_det44_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/dlist.h>
#include <vppinfra/error.h>
#include <vlibapi/api.h>
#include <vlib/log.h>
#include <vnet/fib/fib_table.h>
#include <vnet/fib/ip4_fib.h>
#include <vnet/ip/reass/ip4_sv_reass.h>

#include <nat/lib/lib.h>
#include <nat/lib/inlines.h>

/* Session state */
#define foreach_det44_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) DET44_SESSION_##N = v,
  foreach_det44_session_state
#undef _
} det44_session_state_t;

#define DET44_SES_PER_USER 1000

typedef struct
{
  u16 identifier;
  u16 sequence;
} icmp_echo_header_t;

typedef struct
{
  u16 src_port, dst_port;
} tcp_udp_header_t;

typedef struct
{
  u32 cached_sw_if_index;
  u32 cached_ip4_address;
} det44_runtime_t;

typedef struct nat_timeouts_s
{
  u32 udp;

  struct
  {
    u32 transitory;
    u32 established;
  } tcp;

  u32 icmp;

} nat_timeouts_t;

/* deterministic session outside key */
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
{
  /* Inside network port */
  u16 in_port;
  /* Outside network address and port */
  snat_det_out_key_t out;
  /* Session state */
  u8 state;
  /* Expire timeout */
  u32 expire;
} snat_det_session_t;

typedef struct
{
  /* inside IP address range */
  ip4_address_t in_addr;
  u8 in_plen;
  /* outside IP address range */
  ip4_address_t out_addr;
  u8 out_plen;
  /* inside IP addresses / outside IP addresses */
  u32 sharing_ratio;
  /* number of ports available to internal host */
  u16 ports_per_host;
  /* session counter */
  u32 ses_num;
  /* vector of sessions */
  snat_det_session_t *sessions;
} snat_det_map_t;

typedef struct
{
  u32 sw_if_index;
  u8 flags;
} det44_interface_t;

typedef struct
{

  u32 outside_vrf_id;
  u32 inside_vrf_id;

} det44_config_t;

typedef struct
{
  u32 fib_index;
  u32 refcount;
} det44_fib_t;

typedef struct det44_main_s
{
  det44_config_t config;

  u32 outside_fib_index;
  u32 inside_fib_index;

  /* Vector of outside fibs */
  det44_fib_t *outside_fibs;

  fib_source_t fib_src_hi;
  fib_source_t fib_src_low;

  u32 out2in_node_index;
  u32 in2out_node_index;

  /* Deterministic NAT mappings */
  snat_det_map_t *det_maps;

  /* TCP MSS clamping */
  u16 mss_clamping;

  /* Protocol timeouts */
  nat_timeouts_t timeouts;

  /* Expire walk process node index */
  u32 expire_walk_node_index;

  u32 enabled;

  /* API message ID base */
  u16 msg_id_base;

  /* log class */
  vlib_log_class_t log_class;

  det44_interface_t *interfaces;

  /* convenience */
  ip4_main_t *ip4_main;
  /* required */
  vnet_main_t *vnet_main;

} det44_main_t;

extern det44_main_t det44_main;

/* logging */
#define det44_log_err(...) \
  vlib_log(VLIB_LOG_LEVEL_ERR, det44_main.log_class, __VA_ARGS__)
#define det44_log_warn(...) \
  vlib_log(VLIB_LOG_LEVEL_WARNING, det44_main.log_class, __VA_ARGS__)
#define det44_log_notice(...) \
  vlib_log(VLIB_LOG_LEVEL_NOTICE, det44_main.log_class, __VA_ARGS__)
#define det44_log_info(...) \
  vlib_log(VLIB_LOG_LEVEL_INFO, det44_main.log_class, __VA_ARGS__)
#define det44_log_debug(...)\
  vlib_log(VLIB_LOG_LEVEL_DEBUG, det44_main.log_class, __VA_ARGS__)

/* Deterministic NAT interface flags */
#define DET44_INTERFACE_FLAG_IS_INSIDE 1
#define DET44_INTERFACE_FLAG_IS_OUTSIDE 2

/** \brief Check if Deterministic NAT interface is inside.
    @param i Deterministic NAT interface
    @return 1 if inside interface
*/
#define det44_interface_is_inside(i) i->flags & DET44_INTERFACE_FLAG_IS_INSIDE

/** \brief Check if Deterministic NAT interface is outside.
    @param i Deterministic NAT interface
    @return 1 if outside interface
*/
#define det44_interface_is_outside(i) i->flags & DET44_INTERFACE_FLAG_IS_OUTSIDE

static_always_inline u8
plugin_enabled ()
{
  det44_main_t *dm = &det44_main;
  return dm->enabled;
}

extern vlib_node_registration_t det44_in2out_node;
extern vlib_node_registration_t det44_out2in_node;

int det44_plugin_enable ();
int det44_plugin_disable ();

int det44_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del);

int det44_set_timeouts (nat_timeouts_t * timeouts);
nat_timeouts_t det44_get_timeouts ();
void det44_reset_timeouts ();

/* format functions */
format_function_t format_det_map_ses;

int snat_det_add_map (ip4_address_t * in_addr, u8 in_plen,
		      ip4_address_t * out_addr, u8 out_plen, int is_add);

/* icmp session match functions */
u32 icmp_match_out2in_det (vlib_node_runtime_t * node,
			   u32 thread_index, vlib_buffer_t * b0,
			   ip4_header_t * ip0, ip4_address_t * addr,
			   u16 * port, u32 * fib_index,
			   nat_protocol_t * proto, void *d, void *e,
			   u8 * dont_translate);
u32 icmp_match_in2out_det (vlib_node_runtime_t * node,
			   u32 thread_index, vlib_buffer_t * b0,
			   ip4_header_t * ip0, ip4_address_t * addr,
			   u16 * port, u32 * fib_index,
			   nat_protocol_t * proto, void *d, void *e,
			   u8 * dont_translate);
u32 det44_icmp_in2out (vlib_buffer_t * b0, ip4_header_t * ip0,
		       icmp46_header_t * icmp0, u32 sw_if_index0,
		       u32 rx_fib_index0, vlib_node_runtime_t * node,
		       u32 next0, u32 thread_index, void *d, void *e);
u32 det44_icmp_out2in (vlib_buffer_t * b0, ip4_header_t * ip0,
		       icmp46_header_t * icmp0, u32 sw_if_index0,
		       u32 rx_fib_index0, vlib_node_runtime_t * node,
		       u32 next0, u32 thread_index, void *d, void *e);

static_always_inline int
is_addr_in_net (ip4_address_t * addr, ip4_address_t * net, u8 plen)
{
  if (net->as_u32 == (addr->as_u32 & ip4_main.fib_masks[plen]))
    return 1;
  return 0;
}

static_always_inline snat_det_map_t *
snat_det_map_by_user (ip4_address_t * user_addr)
{
  det44_main_t *dm = &det44_main;
  snat_det_map_t *mp;
  /* *INDENT-OFF* */
  pool_foreach (mp, dm->det_maps,
  ({
    if (is_addr_in_net(user_addr, &mp->in_addr, mp->in_plen))
      return mp;
  }));
  /* *INDENT-ON* */
  return 0;
}

static_always_inline snat_det_map_t *
snat_det_map_by_out (ip4_address_t * out_addr)
{
  det44_main_t *dm = &det44_main;
  snat_det_map_t *mp;
  /* *INDENT-OFF* */
  pool_foreach (mp, dm->det_maps,
  ({
    if (is_addr_in_net(out_addr, &mp->out_addr, mp->out_plen))
      return mp;
  }));
  /* *INDENT-ON* */
  return 0;
}

static_always_inline void
snat_det_forward (snat_det_map_t * dm, ip4_address_t * in_addr,
		  ip4_address_t * out_addr, u16 * lo_port)
{
  u32 in_offset, out_offset;

  in_offset = clib_net_to_host_u32 (in_addr->as_u32) -
    clib_net_to_host_u32 (dm->in_addr.as_u32);
  out_offset = in_offset / dm->sharing_ratio;
  out_addr->as_u32 =
    clib_host_to_net_u32 (clib_net_to_host_u32 (dm->out_addr.as_u32) +
			  out_offset);
  *lo_port = 1024 + dm->ports_per_host * (in_offset % dm->sharing_ratio);
}

static_always_inline void
snat_det_reverse (snat_det_map_t * dm, ip4_address_t * out_addr, u16 out_port,
		  ip4_address_t * in_addr)
{
  u32 in_offset1, in_offset2, out_offset;

  out_offset = clib_net_to_host_u32 (out_addr->as_u32) -
    clib_net_to_host_u32 (dm->out_addr.as_u32);
  in_offset1 = out_offset * dm->sharing_ratio;
  in_offset2 = (out_port - 1024) / dm->ports_per_host;
  in_addr->as_u32 =
    clib_host_to_net_u32 (clib_net_to_host_u32 (dm->in_addr.as_u32) +
			  in_offset1 + in_offset2);
}

static_always_inline u32
snat_det_user_ses_offset (ip4_address_t * addr, u8 plen)
{
  return (clib_net_to_host_u32 (addr->as_u32) & pow2_mask (32 - plen)) *
    DET44_SES_PER_USER;
}

static_always_inline snat_det_session_t *
snat_det_get_ses_by_out (snat_det_map_t * dm, ip4_address_t * in_addr,
			 u64 out_key)
{
  u32 user_offset;
  u16 i;

  user_offset = snat_det_user_ses_offset (in_addr, dm->in_plen);
  for (i = 0; i < DET44_SES_PER_USER; i++)
    {
      if (dm->sessions[i + user_offset].out.as_u64 == out_key)
	return &dm->sessions[i + user_offset];
    }

  return 0;
}

static_always_inline snat_det_session_t *
snat_det_find_ses_by_in (snat_det_map_t * dm, ip4_address_t * in_addr,
			 u16 in_port, snat_det_out_key_t out_key)
{
  snat_det_session_t *ses;
  u32 user_offset;
  u16 i;

  user_offset = snat_det_user_ses_offset (in_addr, dm->in_plen);
  for (i = 0; i < DET44_SES_PER_USER; i++)
    {
      ses = &dm->sessions[i + user_offset];
      if (ses->in_port == in_port &&
	  ses->out.ext_host_addr.as_u32 == out_key.ext_host_addr.as_u32 &&
	  ses->out.ext_host_port == out_key.ext_host_port)
	return &dm->sessions[i + user_offset];
    }

  return 0;
}

static_always_inline snat_det_session_t *
snat_det_ses_create (u32 thread_index, snat_det_map_t * dm,
		     ip4_address_t * in_addr, u16 in_port,
		     snat_det_out_key_t * out)
{
  u32 user_offset;
  u16 i;

  user_offset = snat_det_user_ses_offset (in_addr, dm->in_plen);

  for (i = 0; i < DET44_SES_PER_USER; i++)
    {
      if (!dm->sessions[i + user_offset].in_port)
	{
	  if (clib_atomic_bool_cmp_and_swap
	      (&dm->sessions[i + user_offset].in_port, 0, in_port))
	    {
	      dm->sessions[i + user_offset].out.as_u64 = out->as_u64;
	      dm->sessions[i + user_offset].state = DET44_SESSION_UNKNOWN;
	      dm->sessions[i + user_offset].expire = 0;
	      clib_atomic_add_fetch (&dm->ses_num, 1);
	      return &dm->sessions[i + user_offset];
	    }
	}
    }

  // TODO:
  /*snat_ipfix_logging_max_entries_per_user (thread_index,
     DET44_SES_PER_USER,
     in_addr->as_u32); */
  return 0;
}

static_always_inline void
snat_det_ses_close (snat_det_map_t * dm, snat_det_session_t * ses)
{
  if (clib_atomic_bool_cmp_and_swap (&ses->in_port, ses->in_port, 0))
    {
      ses->out.as_u64 = 0;
      clib_atomic_add_fetch (&dm->ses_num, -1);
    }
}

clib_error_t *det44_api_hookup (vlib_main_t * vm);

#endif /* __included_det44_h__ */

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