ip4_sv_reass.c

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/*
 * Copyright (c) 2017 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 IPv4 Shallow Virtual Reassembly.
 *
 * This file contains the source code for IPv4 Shallow Virtual reassembly.
 */

#include <vppinfra/vec.h>
#include <vnet/vnet.h>
#include <vnet/ip/ip.h>
#include <vnet/ip/ip4_to_ip6.h>
#include <vppinfra/fifo.h>
#include <vppinfra/bihash_16_8.h>
#include <vnet/ip/reass/ip4_sv_reass.h>

#define MSEC_PER_SEC 1000
#define IP4_SV_REASS_TIMEOUT_DEFAULT_MS 100
#define IP4_SV_REASS_EXPIRE_WALK_INTERVAL_DEFAULT_MS 10000      // 10 seconds default
#define IP4_SV_REASS_MAX_REASSEMBLIES_DEFAULT 1024
#define IP4_SV_REASS_MAX_REASSEMBLY_LENGTH_DEFAULT 3
#define IP4_SV_REASS_HT_LOAD_FACTOR (0.75)

typedef enum
{
  IP4_SV_REASS_RC_OK,
  IP4_SV_REASS_RC_TOO_MANY_FRAGMENTS,
  IP4_SV_REASS_RC_UNSUPP_IP_PROTO,
} ip4_sv_reass_rc_t;

typedef struct
{
  union
  {
    struct
    {
      u32 xx_id;
      ip4_address_t src;
      ip4_address_t dst;
      u16 frag_id;
      u8 proto;
      u8 unused;
    };
    u64 as_u64[2];
  };
} ip4_sv_reass_key_t;

typedef union
{
  struct
  {
    u32 reass_index;
    u32 thread_index;
  };
  u64 as_u64;
} ip4_sv_reass_val_t;

typedef union
{
  struct
  {
    ip4_sv_reass_key_t k;
    ip4_sv_reass_val_t v;
  };
  clib_bihash_kv_16_8_t kv;
} ip4_sv_reass_kv_t;

typedef struct
{
  // hash table key
  ip4_sv_reass_key_t key;
  // time when last packet was received
  f64 last_heard;
  // internal id of this reassembly
  u64 id;
  // trace operation counter
  u32 trace_op_counter;
  // minimum fragment length for this reassembly - used to estimate MTU
  u16 min_fragment_length;
  // buffer indexes of buffers in this reassembly in chronological order -
  // including overlaps and duplicate fragments
  u32 *cached_buffers;
  // set to true when this reassembly is completed
  bool is_complete;
  // ip protocol
  u8 ip_proto;
  u8 icmp_type_or_tcp_flags;
  u32 tcp_ack_number;
  u32 tcp_seq_number;
  // l4 src port
  u16 l4_src_port;
  // l4 dst port
  u16 l4_dst_port;
  u32 next_index;
  // lru indexes
  u32 lru_prev;
  u32 lru_next;
} ip4_sv_reass_t;

typedef struct
{
  ip4_sv_reass_t *pool;
  u32 reass_n;
  u32 id_counter;
  clib_spinlock_t lock;
  // lru indexes
  u32 lru_first;
  u32 lru_last;

} ip4_sv_reass_per_thread_t;

typedef struct
{
  // IPv4 config
  u32 timeout_ms;
  f64 timeout;
  u32 expire_walk_interval_ms;
  // maximum number of fragments in one reassembly
  u32 max_reass_len;
  // maximum number of reassemblies
  u32 max_reass_n;

  // IPv4 runtime
  clib_bihash_16_8_t hash;
  // per-thread data
  ip4_sv_reass_per_thread_t *per_thread_data;

  // convenience
  vlib_main_t *vlib_main;
  vnet_main_t *vnet_main;

  // node index of ip4-drop node
  u32 ip4_drop_idx;
  u32 ip4_sv_reass_expire_node_idx;

  /** Worker handoff */
  u32 fq_index;
  u32 fq_feature_index;

  // reference count for enabling/disabling feature - per interface
  u32 *feature_use_refcount_per_intf;

  // reference count for enabling/disabling feature - per interface
  u32 *output_feature_use_refcount_per_intf;

} ip4_sv_reass_main_t;

extern ip4_sv_reass_main_t ip4_sv_reass_main;

#ifndef CLIB_MARCH_VARIANT
ip4_sv_reass_main_t ip4_sv_reass_main;
#endif /* CLIB_MARCH_VARIANT */

typedef enum
{
  IP4_SV_REASSEMBLY_NEXT_INPUT,
  IP4_SV_REASSEMBLY_NEXT_DROP,
  IP4_SV_REASSEMBLY_NEXT_HANDOFF,
  IP4_SV_REASSEMBLY_N_NEXT,
} ip4_sv_reass_next_t;

typedef enum
{
  REASS_FRAGMENT_CACHE,
  REASS_FINISH,
  REASS_FRAGMENT_FORWARD,
  REASS_PASSTHROUGH,
} ip4_sv_reass_trace_operation_e;

typedef struct
{
  ip4_sv_reass_trace_operation_e action;
  u32 reass_id;
  u32 op_id;
  u8 ip_proto;
  u16 l4_src_port;
  u16 l4_dst_port;
} ip4_sv_reass_trace_t;

extern vlib_node_registration_t ip4_sv_reass_node;
extern vlib_node_registration_t ip4_sv_reass_node_feature;

static u8 *
format_ip4_sv_reass_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 *);
  ip4_sv_reass_trace_t *t = va_arg (*args, ip4_sv_reass_trace_t *);
  if (REASS_PASSTHROUGH != t->action)
    {
      s = format (s, "reass id: %u, op id: %u ", t->reass_id, t->op_id);
    }
  switch (t->action)
    {
    case REASS_FRAGMENT_CACHE:
      s = format (s, "[cached]");
      break;
    case REASS_FINISH:
      s =
        format (s, "[finish, ip proto=%u, src_port=%u, dst_port=%u]",
                t->ip_proto, clib_net_to_host_u16 (t->l4_src_port),
                clib_net_to_host_u16 (t->l4_dst_port));
      break;
    case REASS_FRAGMENT_FORWARD:
      s =
        format (s, "[forward, ip proto=%u, src_port=%u, dst_port=%u]",
                t->ip_proto, clib_net_to_host_u16 (t->l4_src_port),
                clib_net_to_host_u16 (t->l4_dst_port));
      break;
    case REASS_PASSTHROUGH:
      s = format (s, "[not-fragmented]");
      break;
    }
  return s;
}

static void
ip4_sv_reass_add_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
                        ip4_sv_reass_main_t * rm, ip4_sv_reass_t * reass,
                        u32 bi, ip4_sv_reass_trace_operation_e action,
                        u32 ip_proto, u16 l4_src_port, u16 l4_dst_port)
{
  vlib_buffer_t *b = vlib_get_buffer (vm, bi);
  ip4_sv_reass_trace_t *t = vlib_add_trace (vm, node, b, sizeof (t[0]));
  if (reass)
    {
      t->reass_id = reass->id;
      t->op_id = reass->trace_op_counter;
      ++reass->trace_op_counter;
    }
  t->action = action;
  t->ip_proto = ip_proto;
  t->l4_src_port = l4_src_port;
  t->l4_dst_port = l4_dst_port;
#if 0
  static u8 *s = NULL;
  s = format (s, "%U", format_ip4_sv_reass_trace, NULL, NULL, t);
  printf ("%.*s\n", vec_len (s), s);
  fflush (stdout);
  vec_reset_length (s);
#endif
}


always_inline void
ip4_sv_reass_free (vlib_main_t * vm, ip4_sv_reass_main_t * rm,
                   ip4_sv_reass_per_thread_t * rt, ip4_sv_reass_t * reass)
{
  clib_bihash_kv_16_8_t kv;
  kv.key[0] = reass->key.as_u64[0];
  kv.key[1] = reass->key.as_u64[1];
  clib_bihash_add_del_16_8 (&rm->hash, &kv, 0);
  vlib_buffer_free (vm, reass->cached_buffers,
                    vec_len (reass->cached_buffers));
  vec_free (reass->cached_buffers);
  reass->cached_buffers = NULL;
  if (~0 != reass->lru_prev)
    {
      ip4_sv_reass_t *lru_prev =
        pool_elt_at_index (rt->pool, reass->lru_prev);
      lru_prev->lru_next = reass->lru_next;
    }
  if (~0 != reass->lru_next)
    {
      ip4_sv_reass_t *lru_next =
        pool_elt_at_index (rt->pool, reass->lru_next);
      lru_next->lru_prev = reass->lru_prev;
    }
  if (rt->lru_first == reass - rt->pool)
    {
      rt->lru_first = reass->lru_next;
    }
  if (rt->lru_last == reass - rt->pool)
    {
      rt->lru_last = reass->lru_prev;
    }
  pool_put (rt->pool, reass);
  --rt->reass_n;
}

always_inline void
ip4_sv_reass_init (ip4_sv_reass_t * reass)
{
  reass->cached_buffers = NULL;
  reass->is_complete = false;
}

always_inline ip4_sv_reass_t *
ip4_sv_reass_find_or_create (vlib_main_t * vm, ip4_sv_reass_main_t * rm,
                             ip4_sv_reass_per_thread_t * rt,
                             ip4_sv_reass_kv_t * kv, u8 * do_handoff)
{
  ip4_sv_reass_t *reass = NULL;
  f64 now = vlib_time_now (vm);

  if (!clib_bihash_search_16_8 (&rm->hash, &kv->kv, &kv->kv))
    {
      if (vm->thread_index != kv->v.thread_index)
        {
          *do_handoff = 1;
          return NULL;
        }
      reass = pool_elt_at_index (rt->pool, kv->v.reass_index);

      if (now > reass->last_heard + rm->timeout)
        {
          ip4_sv_reass_free (vm, rm, rt, reass);
          reass = NULL;
        }
    }

  if (reass)
    {
      reass->last_heard = now;
      return reass;
    }

  if (rt->reass_n >= rm->max_reass_n && rm->max_reass_n)
    {
      reass = pool_elt_at_index (rt->pool, rt->lru_first);
      ip4_sv_reass_free (vm, rm, rt, reass);
    }

  pool_get (rt->pool, reass);
  clib_memset (reass, 0, sizeof (*reass));
  reass->id = ((u64) vm->thread_index * 1000000000) + rt->id_counter;
  ++rt->id_counter;
  ip4_sv_reass_init (reass);
  ++rt->reass_n;
  reass->lru_prev = reass->lru_next = ~0;

  if (~0 != rt->lru_last)
    {
      ip4_sv_reass_t *lru_last = pool_elt_at_index (rt->pool, rt->lru_last);
      reass->lru_prev = rt->lru_last;
      lru_last->lru_next = rt->lru_last = reass - rt->pool;
    }

  if (~0 == rt->lru_first)
    {
      rt->lru_first = rt->lru_last = reass - rt->pool;
    }

  reass->key.as_u64[0] = kv->kv.key[0];
  reass->key.as_u64[1] = kv->kv.key[1];
  kv->v.reass_index = (reass - rt->pool);
  kv->v.thread_index = vm->thread_index;
  reass->last_heard = now;

  if (clib_bihash_add_del_16_8 (&rm->hash, &kv->kv, 1))
    {
      ip4_sv_reass_free (vm, rm, rt, reass);
      reass = NULL;
    }

  return reass;
}

always_inline ip4_sv_reass_rc_t
ip4_sv_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
                     ip4_sv_reass_main_t * rm, ip4_sv_reass_per_thread_t * rt,
                     ip4_header_t * ip0, ip4_sv_reass_t * reass, u32 bi0)
{
  vlib_buffer_t *b0 = vlib_get_buffer (vm, bi0);
  ip4_sv_reass_rc_t rc = IP4_SV_REASS_RC_OK;
  const u32 fragment_first = ip4_get_fragment_offset_bytes (ip0);
  if (0 == fragment_first)
    {
      reass->ip_proto = ip0->protocol;
      reass->l4_src_port = ip4_get_port (ip0, 1);
      reass->l4_dst_port = ip4_get_port (ip0, 0);
      if (!reass->l4_src_port || !reass->l4_dst_port)
        return IP4_SV_REASS_RC_UNSUPP_IP_PROTO;
      if (IP_PROTOCOL_TCP == reass->ip_proto)
        {
          reass->icmp_type_or_tcp_flags = ((tcp_header_t *) (ip0 + 1))->flags;
          reass->tcp_ack_number = ((tcp_header_t *) (ip0 + 1))->ack_number;
          reass->tcp_seq_number = ((tcp_header_t *) (ip0 + 1))->seq_number;
        }
      else if (IP_PROTOCOL_ICMP == reass->ip_proto)
        {
          reass->icmp_type_or_tcp_flags =
            ((icmp46_header_t *) (ip0 + 1))->type;
        }
      reass->is_complete = true;
      vlib_buffer_t *b0 = vlib_get_buffer (vm, bi0);
      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
        {
          ip4_sv_reass_add_trace (vm, node, rm, reass, bi0, REASS_FINISH,
                                  reass->ip_proto, reass->l4_src_port,
                                  reass->l4_dst_port);
        }
    }
  vec_add1 (reass->cached_buffers, bi0);
  if (!reass->is_complete)
    {
      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
        {
          ip4_sv_reass_add_trace (vm, node, rm, reass, bi0,
                                  REASS_FRAGMENT_CACHE, ~0, ~0, ~0);
        }
      if (vec_len (reass->cached_buffers) > rm->max_reass_len)
        {
          rc = IP4_SV_REASS_RC_TOO_MANY_FRAGMENTS;
        }
    }
  return rc;
}

always_inline uword
ip4_sv_reass_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
                     vlib_frame_t * frame, bool is_feature,
                     bool is_output_feature, bool is_custom)
{
  u32 *from = vlib_frame_vector_args (frame);
  u32 n_left_from, n_left_to_next, *to_next, next_index;
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;
  ip4_sv_reass_per_thread_t *rt = &rm->per_thread_data[vm->thread_index];
  clib_spinlock_lock (&rt->lock);

  n_left_from = frame->n_vectors;
  next_index = node->cached_next_index;

  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
  vlib_get_buffers (vm, from, bufs, n_left_from);
  u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
  b = bufs;

  /* optimistic case first - no fragments */
  while (n_left_from >= 2)
    {
      vlib_buffer_t *b0, *b1;
      u32 next0, next1;
      b0 = *b;
      b++;
      b1 = *b;
      b++;

      /* Prefetch next iteration. */
      if (PREDICT_TRUE (n_left_from >= 4))
        {
          vlib_buffer_t *p2, *p3;

          p2 = *b;
          p3 = *(b + 1);

          vlib_prefetch_buffer_header (p2, LOAD);
          vlib_prefetch_buffer_header (p3, LOAD);

          CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, LOAD);
          CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, LOAD);
        }

      ip4_header_t *ip0 =
        (ip4_header_t *) u8_ptr_add (vlib_buffer_get_current (b0),
                                     (is_output_feature ? 1 : 0) *
                                     vnet_buffer (b0)->
                                     ip.save_rewrite_length);
      ip4_header_t *ip1 =
        (ip4_header_t *) u8_ptr_add (vlib_buffer_get_current (b1),
                                     (is_output_feature ? 1 : 0) *
                                     vnet_buffer (b1)->
                                     ip.save_rewrite_length);
      if (PREDICT_FALSE
          (ip4_get_fragment_more (ip0) || ip4_get_fragment_offset (ip0))
          || (ip4_get_fragment_more (ip1) || ip4_get_fragment_offset (ip1)))
        {
          // fragment found, go slow path
          b -= 2;
          if (b - bufs > 0)
            {
              vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
                                           b - bufs);
            }
          goto slow_path;
        }
      if (is_feature)
        {
          vnet_feature_next (&next0, b0);
        }
      else
        {
          next0 = is_custom ? vnet_buffer (b0)->ip.reass.next_index :
            IP4_SV_REASSEMBLY_NEXT_INPUT;
        }
      vnet_buffer (b0)->ip.reass.is_non_first_fragment = 0;
      vnet_buffer (b0)->ip.reass.ip_proto = ip0->protocol;
      if (IP_PROTOCOL_TCP == ip0->protocol)
        {
          vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
            ((tcp_header_t *) (ip0 + 1))->flags;
          vnet_buffer (b0)->ip.reass.tcp_ack_number =
            ((tcp_header_t *) (ip0 + 1))->ack_number;
          vnet_buffer (b0)->ip.reass.tcp_seq_number =
            ((tcp_header_t *) (ip0 + 1))->seq_number;
        }
      else if (IP_PROTOCOL_ICMP == ip0->protocol)
        {
          vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
            ((icmp46_header_t *) (ip0 + 1))->type;
        }
      vnet_buffer (b0)->ip.reass.l4_src_port = ip4_get_port (ip0, 1);
      vnet_buffer (b0)->ip.reass.l4_dst_port = ip4_get_port (ip0, 0);
      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
        {
          ip4_sv_reass_add_trace (vm, node, rm, NULL, from[(b - 2) - bufs],
                                  REASS_PASSTHROUGH,
                                  vnet_buffer (b0)->ip.reass.ip_proto,
                                  vnet_buffer (b0)->ip.reass.l4_src_port,
                                  vnet_buffer (b0)->ip.reass.l4_dst_port);
        }
      if (is_feature)
        {
          vnet_feature_next (&next1, b1);
        }
      else
        {
          next1 = is_custom ? vnet_buffer (b1)->ip.reass.next_index :
            IP4_SV_REASSEMBLY_NEXT_INPUT;
        }
      vnet_buffer (b1)->ip.reass.is_non_first_fragment = 0;
      vnet_buffer (b1)->ip.reass.ip_proto = ip1->protocol;
      if (IP_PROTOCOL_TCP == ip1->protocol)
        {
          vnet_buffer (b1)->ip.reass.icmp_type_or_tcp_flags =
            ((tcp_header_t *) (ip1 + 1))->flags;
          vnet_buffer (b1)->ip.reass.tcp_ack_number =
            ((tcp_header_t *) (ip1 + 1))->ack_number;
          vnet_buffer (b1)->ip.reass.tcp_seq_number =
            ((tcp_header_t *) (ip1 + 1))->seq_number;
        }
      else if (IP_PROTOCOL_ICMP == ip1->protocol)
        {
          vnet_buffer (b1)->ip.reass.icmp_type_or_tcp_flags =
            ((icmp46_header_t *) (ip1 + 1))->type;
        }
      vnet_buffer (b1)->ip.reass.l4_src_port = ip4_get_port (ip1, 1);
      vnet_buffer (b1)->ip.reass.l4_dst_port = ip4_get_port (ip1, 0);
      if (PREDICT_FALSE (b1->flags & VLIB_BUFFER_IS_TRACED))
        {
          ip4_sv_reass_add_trace (vm, node, rm, NULL, from[(b - 1) - bufs],
                                  REASS_PASSTHROUGH,
                                  vnet_buffer (b1)->ip.reass.ip_proto,
                                  vnet_buffer (b1)->ip.reass.l4_src_port,
                                  vnet_buffer (b1)->ip.reass.l4_dst_port);
        }

      n_left_from -= 2;
      next[0] = next0;
      next[1] = next1;
      next += 2;
    }

  while (n_left_from > 0)
    {
      vlib_buffer_t *b0;
      u32 next0;
      b0 = *b;
      b++;

      ip4_header_t *ip0 =
        (ip4_header_t *) u8_ptr_add (vlib_buffer_get_current (b0),
                                     (is_output_feature ? 1 : 0) *
                                     vnet_buffer (b0)->
                                     ip.save_rewrite_length);
      if (PREDICT_FALSE
          (ip4_get_fragment_more (ip0) || ip4_get_fragment_offset (ip0)))
        {
          // fragment found, go slow path
          b -= 1;
          if (b - bufs > 0)
            {
              vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
                                           b - bufs);
            }
          goto slow_path;
        }
      if (is_feature)
        {
          vnet_feature_next (&next0, b0);
        }
      else
        {
          next0 =
            is_custom ? vnet_buffer (b0)->ip.
            reass.next_index : IP4_SV_REASSEMBLY_NEXT_INPUT;
        }
      vnet_buffer (b0)->ip.reass.is_non_first_fragment = 0;
      vnet_buffer (b0)->ip.reass.ip_proto = ip0->protocol;
      if (IP_PROTOCOL_TCP == ip0->protocol)
        {
          vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
            ((tcp_header_t *) (ip0 + 1))->flags;
          vnet_buffer (b0)->ip.reass.tcp_ack_number =
            ((tcp_header_t *) (ip0 + 1))->ack_number;
          vnet_buffer (b0)->ip.reass.tcp_seq_number =
            ((tcp_header_t *) (ip0 + 1))->seq_number;
        }
      else if (IP_PROTOCOL_ICMP == ip0->protocol)
        {
          vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
            ((icmp46_header_t *) (ip0 + 1))->type;
        }
      vnet_buffer (b0)->ip.reass.l4_src_port = ip4_get_port (ip0, 1);
      vnet_buffer (b0)->ip.reass.l4_dst_port = ip4_get_port (ip0, 0);
      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
        {
          ip4_sv_reass_add_trace (vm, node, rm, NULL, from[(b - 1) - bufs],
                                  REASS_PASSTHROUGH,
                                  vnet_buffer (b0)->ip.reass.ip_proto,
                                  vnet_buffer (b0)->ip.reass.l4_src_port,
                                  vnet_buffer (b0)->ip.reass.l4_dst_port);
        }

      n_left_from -= 1;
      next[0] = next0;
      next += 1;
    }

  vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
                               frame->n_vectors);

  goto done;

slow_path:

  from += b - bufs;

  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;
          vlib_buffer_t *b0;
          u32 next0;
          u32 error0 = IP4_ERROR_NONE;

          bi0 = from[0];
          b0 = vlib_get_buffer (vm, bi0);

          ip4_header_t *ip0 =
            (ip4_header_t *) u8_ptr_add (vlib_buffer_get_current (b0),
                                         (is_output_feature ? 1 : 0) *
                                         vnet_buffer (b0)->
                                         ip.save_rewrite_length);
          if (!ip4_get_fragment_more (ip0) && !ip4_get_fragment_offset (ip0))
            {
              // this is a regular packet - no fragmentation
              if (is_custom)
                {
                  next0 = vnet_buffer (b0)->ip.reass.next_index;
                }
              else
                {
                  next0 = IP4_SV_REASSEMBLY_NEXT_INPUT;
                }
              vnet_buffer (b0)->ip.reass.is_non_first_fragment = 0;
              vnet_buffer (b0)->ip.reass.ip_proto = ip0->protocol;
              if (IP_PROTOCOL_TCP == ip0->protocol)
                {
                  vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
                    ((tcp_header_t *) (ip0 + 1))->flags;
                  vnet_buffer (b0)->ip.reass.tcp_ack_number =
                    ((tcp_header_t *) (ip0 + 1))->ack_number;
                  vnet_buffer (b0)->ip.reass.tcp_seq_number =
                    ((tcp_header_t *) (ip0 + 1))->seq_number;
                }
              else if (IP_PROTOCOL_ICMP == ip0->protocol)
                {
                  vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
                    ((icmp46_header_t *) (ip0 + 1))->type;
                }
              vnet_buffer (b0)->ip.reass.l4_src_port = ip4_get_port (ip0, 1);
              vnet_buffer (b0)->ip.reass.l4_dst_port = ip4_get_port (ip0, 0);
              if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
                {
                  ip4_sv_reass_add_trace (vm, node, rm, NULL, bi0,
                                          REASS_PASSTHROUGH,
                                          vnet_buffer (b0)->ip.reass.ip_proto,
                                          vnet_buffer (b0)->ip.
                                          reass.l4_src_port,
                                          vnet_buffer (b0)->ip.
                                          reass.l4_dst_port);
                }
              goto packet_enqueue;
            }
          const u32 fragment_first = ip4_get_fragment_offset_bytes (ip0);
          const u32 fragment_length =
            clib_net_to_host_u16 (ip0->length) - ip4_header_bytes (ip0);
          const u32 fragment_last = fragment_first + fragment_length - 1;
          if (fragment_first > fragment_last || fragment_first + fragment_length > UINT16_MAX - 20 || (fragment_length < 8 && ip4_get_fragment_more (ip0)))     // 8 is minimum frag length per RFC 791
            {
              next0 = IP4_SV_REASSEMBLY_NEXT_DROP;
              error0 = IP4_ERROR_REASS_MALFORMED_PACKET;
              b0->error = node->errors[error0];
              goto packet_enqueue;
            }
          ip4_sv_reass_kv_t kv;
          u8 do_handoff = 0;

          kv.k.as_u64[0] =
            (u64) vec_elt (ip4_main.fib_index_by_sw_if_index,
                           vnet_buffer (b0)->sw_if_index[VLIB_RX]) |
            (u64) ip0->src_address.as_u32 << 32;
          kv.k.as_u64[1] =
            (u64) ip0->dst_address.
            as_u32 | (u64) ip0->fragment_id << 32 | (u64) ip0->protocol << 48;

          ip4_sv_reass_t *reass =
            ip4_sv_reass_find_or_create (vm, rm, rt, &kv, &do_handoff);

          if (PREDICT_FALSE (do_handoff))
            {
              next0 = IP4_SV_REASSEMBLY_NEXT_HANDOFF;
              vnet_buffer (b0)->ip.reass.owner_thread_index =
                kv.v.thread_index;
              goto packet_enqueue;
            }

          if (!reass)
            {
              next0 = IP4_SV_REASSEMBLY_NEXT_DROP;
              error0 = IP4_ERROR_REASS_LIMIT_REACHED;
              b0->error = node->errors[error0];
              goto packet_enqueue;
            }

          if (reass->is_complete)
            {
              if (is_custom)
                {
                  next0 = vnet_buffer (b0)->ip.reass.next_index;
                }
              else
                {
                  next0 = IP4_SV_REASSEMBLY_NEXT_INPUT;
                }
              vnet_buffer (b0)->ip.reass.is_non_first_fragment =
                ! !fragment_first;
              vnet_buffer (b0)->ip.reass.ip_proto = reass->ip_proto;
              vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
                reass->icmp_type_or_tcp_flags;
              vnet_buffer (b0)->ip.reass.tcp_ack_number =
                reass->tcp_ack_number;
              vnet_buffer (b0)->ip.reass.tcp_seq_number =
                reass->tcp_seq_number;
              vnet_buffer (b0)->ip.reass.l4_src_port = reass->l4_src_port;
              vnet_buffer (b0)->ip.reass.l4_dst_port = reass->l4_dst_port;
              if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
                {
                  ip4_sv_reass_add_trace (vm, node, rm, reass, bi0,
                                          REASS_FRAGMENT_FORWARD,
                                          reass->ip_proto,
                                          reass->l4_src_port,
                                          reass->l4_dst_port);
                }
              goto packet_enqueue;
            }

          ip4_sv_reass_rc_t rc =
            ip4_sv_reass_update (vm, node, rm, rt, ip0, reass, bi0);
          switch (rc)
            {
            case IP4_SV_REASS_RC_OK:
              /* nothing to do here */
              break;
            case IP4_SV_REASS_RC_TOO_MANY_FRAGMENTS:
              vlib_node_increment_counter (vm, node->node_index,
                                           IP4_ERROR_REASS_FRAGMENT_CHAIN_TOO_LONG,
                                           1);
              ip4_sv_reass_free (vm, rm, rt, reass);
              goto next_packet;
              break;
            case IP4_SV_REASS_RC_UNSUPP_IP_PROTO:
              vlib_node_increment_counter (vm, node->node_index,
                                           IP4_ERROR_REASS_FRAGMENT_CHAIN_TOO_LONG,
                                           1);
              ip4_sv_reass_free (vm, rm, rt, reass);
              goto next_packet;
              break;
            }
          if (reass->is_complete)
            {
              u32 idx;
              vec_foreach_index (idx, reass->cached_buffers)
              {
                u32 bi0 = vec_elt (reass->cached_buffers, idx);
                vlib_buffer_t *b0 = vlib_get_buffer (vm, bi0);
                ip0 =
                  (ip4_header_t *) u8_ptr_add (vlib_buffer_get_current (b0),
                                               (is_output_feature ? 1 : 0) *
                                               vnet_buffer (b0)->
                                               ip.save_rewrite_length);
                u32 next0 = IP4_SV_REASSEMBLY_NEXT_INPUT;
                if (is_feature)
                  {
                    vnet_feature_next (&next0, b0);
                  }
                if (is_custom)
                  {
                    next0 = vnet_buffer (b0)->ip.reass.next_index;
                  }
                if (0 == n_left_to_next)
                  {
                    vlib_put_next_frame (vm, node, next_index,
                                         n_left_to_next);
                    vlib_get_next_frame (vm, node, next_index, to_next,
                                         n_left_to_next);
                  }
                to_next[0] = bi0;
                to_next += 1;
                n_left_to_next -= 1;
                vnet_buffer (b0)->ip.reass.is_non_first_fragment =
                  ! !ip4_get_fragment_offset (ip0);
                vnet_buffer (b0)->ip.reass.ip_proto = reass->ip_proto;
                vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
                  reass->icmp_type_or_tcp_flags;
                vnet_buffer (b0)->ip.reass.tcp_ack_number =
                  reass->tcp_ack_number;
                vnet_buffer (b0)->ip.reass.tcp_seq_number =
                  reass->tcp_seq_number;
                vnet_buffer (b0)->ip.reass.l4_src_port = reass->l4_src_port;
                vnet_buffer (b0)->ip.reass.l4_dst_port = reass->l4_dst_port;
                if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
                  {
                    ip4_sv_reass_add_trace (vm, node, rm, reass, bi0,
                                            REASS_FRAGMENT_FORWARD,
                                            reass->ip_proto,
                                            reass->l4_src_port,
                                            reass->l4_dst_port);
                  }
                vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                                 to_next, n_left_to_next, bi0,
                                                 next0);
              }
              _vec_len (reass->cached_buffers) = 0;     // buffers are owned by frame now
            }
          goto next_packet;

        packet_enqueue:
          to_next[0] = bi0;
          to_next += 1;
          n_left_to_next -= 1;
          if (is_feature && IP4_ERROR_NONE == error0)
            {
              b0 = vlib_get_buffer (vm, bi0);
              vnet_feature_next (&next0, b0);
            }
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, next0);

        next_packet:
          from += 1;
          n_left_from -= 1;
        }

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

done:
  clib_spinlock_unlock (&rt->lock);
  return frame->n_vectors;
}

static char *ip4_sv_reass_error_strings[] = {
#define _(sym, string) string,
  foreach_ip4_error
#undef _
};

VLIB_NODE_FN (ip4_sv_reass_node) (vlib_main_t * vm,
                                  vlib_node_runtime_t * node,
                                  vlib_frame_t * frame)
{
  return ip4_sv_reass_inline (vm, node, frame, false /* is_feature */ ,
                              false /* is_output_feature */ ,
                              false /* is_custom */ );
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip4_sv_reass_node) = {
    .name = "ip4-sv-reassembly",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_sv_reass_trace,
    .n_errors = ARRAY_LEN (ip4_sv_reass_error_strings),
    .error_strings = ip4_sv_reass_error_strings,
    .n_next_nodes = IP4_SV_REASSEMBLY_N_NEXT,
    .next_nodes =
        {
                [IP4_SV_REASSEMBLY_NEXT_INPUT] = "ip4-input",
                [IP4_SV_REASSEMBLY_NEXT_DROP] = "ip4-drop",
                [IP4_SV_REASSEMBLY_NEXT_HANDOFF] = "ip4-sv-reassembly-handoff",

        },
};
/* *INDENT-ON* */

VLIB_NODE_FN (ip4_sv_reass_node_feature) (vlib_main_t * vm,
                                          vlib_node_runtime_t * node,
                                          vlib_frame_t * frame)
{
  return ip4_sv_reass_inline (vm, node, frame, true /* is_feature */ ,
                              false /* is_output_feature */ ,
                              false /* is_custom */ );
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip4_sv_reass_node_feature) = {
    .name = "ip4-sv-reassembly-feature",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_sv_reass_trace,
    .n_errors = ARRAY_LEN (ip4_sv_reass_error_strings),
    .error_strings = ip4_sv_reass_error_strings,
    .n_next_nodes = IP4_SV_REASSEMBLY_N_NEXT,
    .next_nodes =
        {
                [IP4_SV_REASSEMBLY_NEXT_INPUT] = "ip4-input",
                [IP4_SV_REASSEMBLY_NEXT_DROP] = "ip4-drop",
                [IP4_SV_REASSEMBLY_NEXT_HANDOFF] = "ip4-sv-reass-feature-hoff",
        },
};
/* *INDENT-ON* */

/* *INDENT-OFF* */
VNET_FEATURE_INIT (ip4_sv_reass_feature) = {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-sv-reassembly-feature",
    .runs_before = VNET_FEATURES ("ip4-lookup"),
    .runs_after = 0,
};
/* *INDENT-ON* */

VLIB_NODE_FN (ip4_sv_reass_node_output_feature) (vlib_main_t * vm,
                                                 vlib_node_runtime_t * node,
                                                 vlib_frame_t * frame)
{
  return ip4_sv_reass_inline (vm, node, frame, true /* is_feature */ ,
                              true /* is_output_feature */ ,
                              false /* is_custom */ );
}


/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip4_sv_reass_node_output_feature) = {
    .name = "ip4-sv-reassembly-output-feature",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_sv_reass_trace,
    .n_errors = ARRAY_LEN (ip4_sv_reass_error_strings),
    .error_strings = ip4_sv_reass_error_strings,
    .n_next_nodes = IP4_SV_REASSEMBLY_N_NEXT,
    .next_nodes =
        {
                [IP4_SV_REASSEMBLY_NEXT_INPUT] = "ip4-input",
                [IP4_SV_REASSEMBLY_NEXT_DROP] = "ip4-drop",
                [IP4_SV_REASSEMBLY_NEXT_HANDOFF] = "ip4-sv-reass-feature-hoff",
        },
};
/* *INDENT-ON* */

/* *INDENT-OFF* */
VNET_FEATURE_INIT (ip4_sv_reass_output_feature) = {
    .arc_name = "ip4-output",
    .node_name = "ip4-sv-reassembly-output-feature",
    .runs_before = 0,
    .runs_after = 0,
};
/* *INDENT-ON* */

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip4_sv_reass_custom_node) = {
    .name = "ip4-sv-reassembly-custom-next",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_sv_reass_trace,
    .n_errors = ARRAY_LEN (ip4_sv_reass_error_strings),
    .error_strings = ip4_sv_reass_error_strings,
    .n_next_nodes = IP4_SV_REASSEMBLY_N_NEXT,
    .next_nodes =
        {
                [IP4_SV_REASSEMBLY_NEXT_INPUT] = "ip4-input",
                [IP4_SV_REASSEMBLY_NEXT_DROP] = "ip4-drop",
                [IP4_SV_REASSEMBLY_NEXT_HANDOFF] = "ip4-sv-reassembly-handoff",

        },
};
/* *INDENT-ON* */

VLIB_NODE_FN (ip4_sv_reass_custom_node) (vlib_main_t * vm,
                                         vlib_node_runtime_t * node,
                                         vlib_frame_t * frame)
{
  return ip4_sv_reass_inline (vm, node, frame, false /* is_feature */ ,
                              false /* is_output_feature */ ,
                              true /* is_custom */ );
}

#ifndef CLIB_MARCH_VARIANT
always_inline u32
ip4_sv_reass_get_nbuckets ()
{
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;
  u32 nbuckets;
  u8 i;

  nbuckets = (u32) (rm->max_reass_n / IP4_SV_REASS_HT_LOAD_FACTOR);

  for (i = 0; i < 31; i++)
    if ((1 << i) >= nbuckets)
      break;
  nbuckets = 1 << i;

  return nbuckets;
}
#endif /* CLIB_MARCH_VARIANT */

typedef enum
{
  IP4_EVENT_CONFIG_CHANGED = 1,
} ip4_sv_reass_event_t;

typedef struct
{
  int failure;
  clib_bihash_16_8_t *new_hash;
} ip4_rehash_cb_ctx;

#ifndef CLIB_MARCH_VARIANT
static int
ip4_rehash_cb (clib_bihash_kv_16_8_t * kv, void *_ctx)
{
  ip4_rehash_cb_ctx *ctx = _ctx;
  if (clib_bihash_add_del_16_8 (ctx->new_hash, kv, 1))
    {
      ctx->failure = 1;
    }
  return (BIHASH_WALK_CONTINUE);
}

static void
ip4_sv_reass_set_params (u32 timeout_ms, u32 max_reassemblies,
                         u32 max_reassembly_length,
                         u32 expire_walk_interval_ms)
{
  ip4_sv_reass_main.timeout_ms = timeout_ms;
  ip4_sv_reass_main.timeout = (f64) timeout_ms / (f64) MSEC_PER_SEC;
  ip4_sv_reass_main.max_reass_n = max_reassemblies;
  ip4_sv_reass_main.max_reass_len = max_reassembly_length;
  ip4_sv_reass_main.expire_walk_interval_ms = expire_walk_interval_ms;
}

vnet_api_error_t
ip4_sv_reass_set (u32 timeout_ms, u32 max_reassemblies,
                  u32 max_reassembly_length, u32 expire_walk_interval_ms)
{
  u32 old_nbuckets = ip4_sv_reass_get_nbuckets ();
  ip4_sv_reass_set_params (timeout_ms, max_reassemblies,
                           max_reassembly_length, expire_walk_interval_ms);
  vlib_process_signal_event (ip4_sv_reass_main.vlib_main,
                             ip4_sv_reass_main.ip4_sv_reass_expire_node_idx,
                             IP4_EVENT_CONFIG_CHANGED, 0);
  u32 new_nbuckets = ip4_sv_reass_get_nbuckets ();
  if (ip4_sv_reass_main.max_reass_n > 0 && new_nbuckets > old_nbuckets)
    {
      clib_bihash_16_8_t new_hash;
      clib_memset (&new_hash, 0, sizeof (new_hash));
      ip4_rehash_cb_ctx ctx;
      ctx.failure = 0;
      ctx.new_hash = &new_hash;
      clib_bihash_init_16_8 (&new_hash, "ip4-dr", new_nbuckets,
                             new_nbuckets * 1024);
      clib_bihash_foreach_key_value_pair_16_8 (&ip4_sv_reass_main.hash,
                                               ip4_rehash_cb, &ctx);
      if (ctx.failure)
        {
          clib_bihash_free_16_8 (&new_hash);
          return -1;
        }
      else
        {
          clib_bihash_free_16_8 (&ip4_sv_reass_main.hash);
          clib_memcpy_fast (&ip4_sv_reass_main.hash, &new_hash,
                            sizeof (ip4_sv_reass_main.hash));
          clib_bihash_copied (&ip4_sv_reass_main.hash, &new_hash);
        }
    }
  return 0;
}

vnet_api_error_t
ip4_sv_reass_get (u32 * timeout_ms, u32 * max_reassemblies,
                  u32 * max_reassembly_length, u32 * expire_walk_interval_ms)
{
  *timeout_ms = ip4_sv_reass_main.timeout_ms;
  *max_reassemblies = ip4_sv_reass_main.max_reass_n;
  *max_reassembly_length = ip4_sv_reass_main.max_reass_len;
  *expire_walk_interval_ms = ip4_sv_reass_main.expire_walk_interval_ms;
  return 0;
}

static clib_error_t *
ip4_sv_reass_init_function (vlib_main_t * vm)
{
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;
  clib_error_t *error = 0;
  u32 nbuckets;
  vlib_node_t *node;

  rm->vlib_main = vm;
  rm->vnet_main = vnet_get_main ();

  vec_validate (rm->per_thread_data, vlib_num_workers ());
  ip4_sv_reass_per_thread_t *rt;
  vec_foreach (rt, rm->per_thread_data)
  {
    clib_spinlock_init (&rt->lock);
    pool_alloc (rt->pool, rm->max_reass_n);
    rt->lru_first = rt->lru_last = ~0;
  }

  node = vlib_get_node_by_name (vm, (u8 *) "ip4-sv-reassembly-expire-walk");
  ASSERT (node);
  rm->ip4_sv_reass_expire_node_idx = node->index;

  ip4_sv_reass_set_params (IP4_SV_REASS_TIMEOUT_DEFAULT_MS,
                           IP4_SV_REASS_MAX_REASSEMBLIES_DEFAULT,
                           IP4_SV_REASS_MAX_REASSEMBLY_LENGTH_DEFAULT,
                           IP4_SV_REASS_EXPIRE_WALK_INTERVAL_DEFAULT_MS);

  nbuckets = ip4_sv_reass_get_nbuckets ();
  clib_bihash_init_16_8 (&rm->hash, "ip4-dr", nbuckets, nbuckets * 1024);

  node = vlib_get_node_by_name (vm, (u8 *) "ip4-drop");
  ASSERT (node);
  rm->ip4_drop_idx = node->index;

  rm->fq_index = vlib_frame_queue_main_init (ip4_sv_reass_node.index, 0);
  rm->fq_feature_index =
    vlib_frame_queue_main_init (ip4_sv_reass_node_feature.index, 0);

  rm->feature_use_refcount_per_intf = NULL;
  rm->output_feature_use_refcount_per_intf = NULL;

  return error;
}

VLIB_INIT_FUNCTION (ip4_sv_reass_init_function);
#endif /* CLIB_MARCH_VARIANT */

static uword
ip4_sv_reass_walk_expired (vlib_main_t * vm,
                           vlib_node_runtime_t * node, vlib_frame_t * f)
{
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;
  uword event_type, *event_data = 0;

  while (true)
    {
      vlib_process_wait_for_event_or_clock (vm,
                                            (f64)
                                            rm->expire_walk_interval_ms /
                                            (f64) MSEC_PER_SEC);
      event_type = vlib_process_get_events (vm, &event_data);

      switch (event_type)
        {
        case ~0:                /* no events => timeout */
          /* nothing to do here */
          break;
        case IP4_EVENT_CONFIG_CHANGED:
          break;
        default:
          clib_warning ("BUG: event type 0x%wx", event_type);
          break;
        }
      f64 now = vlib_time_now (vm);

      ip4_sv_reass_t *reass;
      int *pool_indexes_to_free = NULL;

      uword thread_index = 0;
      int index;
      const uword nthreads = vlib_num_workers () + 1;
      for (thread_index = 0; thread_index < nthreads; ++thread_index)
        {
          ip4_sv_reass_per_thread_t *rt = &rm->per_thread_data[thread_index];
          clib_spinlock_lock (&rt->lock);

          vec_reset_length (pool_indexes_to_free);
          /* *INDENT-OFF* */
          pool_foreach_index (index, rt->pool, ({
                                reass = pool_elt_at_index (rt->pool, index);
                                if (now > reass->last_heard + rm->timeout)
                                  {
                                    vec_add1 (pool_indexes_to_free, index);
                                  }
                              }));
          /* *INDENT-ON* */
          int *i;
          /* *INDENT-OFF* */
          vec_foreach (i, pool_indexes_to_free)
          {
            ip4_sv_reass_t *reass = pool_elt_at_index (rt->pool, i[0]);
            ip4_sv_reass_free (vm, rm, rt, reass);
          }
          /* *INDENT-ON* */

          clib_spinlock_unlock (&rt->lock);
        }

      vec_free (pool_indexes_to_free);
      if (event_data)
        {
          _vec_len (event_data) = 0;
        }
    }

  return 0;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip4_sv_reass_expire_node) = {
    .function = ip4_sv_reass_walk_expired,
    .type = VLIB_NODE_TYPE_PROCESS,
    .name = "ip4-sv-reassembly-expire-walk",
    .format_trace = format_ip4_sv_reass_trace,
    .n_errors = ARRAY_LEN (ip4_sv_reass_error_strings),
    .error_strings = ip4_sv_reass_error_strings,

};
/* *INDENT-ON* */

static u8 *
format_ip4_sv_reass_key (u8 * s, va_list * args)
{
  ip4_sv_reass_key_t *key = va_arg (*args, ip4_sv_reass_key_t *);
  s =
    format (s,
            "xx_id: %u, src: %U, dst: %U, frag_id: %u, proto: %u",
            key->xx_id, format_ip4_address, &key->src, format_ip4_address,
            &key->dst, clib_net_to_host_u16 (key->frag_id), key->proto);
  return s;
}

static u8 *
format_ip4_sv_reass (u8 * s, va_list * args)
{
  vlib_main_t *vm = va_arg (*args, vlib_main_t *);
  ip4_sv_reass_t *reass = va_arg (*args, ip4_sv_reass_t *);

  s = format (s, "ID: %lu, key: %U trace_op_counter: %u\n",
              reass->id, format_ip4_sv_reass_key, &reass->key,
              reass->trace_op_counter);

  vlib_buffer_t *b;
  u32 *bip;
  u32 counter = 0;
  vec_foreach (bip, reass->cached_buffers)
  {
    u32 bi = *bip;
    do
      {
        b = vlib_get_buffer (vm, bi);
        s = format (s, "  #%03u: bi: %u, ", counter, bi);
        ++counter;
        bi = b->next_buffer;
      }
    while (b->flags & VLIB_BUFFER_NEXT_PRESENT);
  }
  return s;
}

static clib_error_t *
show_ip4_reass (vlib_main_t * vm,
                unformat_input_t * input,
                CLIB_UNUSED (vlib_cli_command_t * lmd))
{
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;

  vlib_cli_output (vm, "---------------------");
  vlib_cli_output (vm, "IP4 reassembly status");
  vlib_cli_output (vm, "---------------------");
  bool details = false;
  if (unformat (input, "details"))
    {
      details = true;
    }

  u32 sum_reass_n = 0;
  ip4_sv_reass_t *reass;
  uword thread_index;
  const uword nthreads = vlib_num_workers () + 1;
  for (thread_index = 0; thread_index < nthreads; ++thread_index)
    {
      ip4_sv_reass_per_thread_t *rt = &rm->per_thread_data[thread_index];
      clib_spinlock_lock (&rt->lock);
      if (details)
        {
          /* *INDENT-OFF* */
          pool_foreach (reass, rt->pool, {
            vlib_cli_output (vm, "%U", format_ip4_sv_reass, vm, reass);
          });
          /* *INDENT-ON* */
        }
      sum_reass_n += rt->reass_n;
      clib_spinlock_unlock (&rt->lock);
    }
  vlib_cli_output (vm, "---------------------");
  vlib_cli_output (vm, "Current IP4 reassemblies count: %lu\n",
                   (long unsigned) sum_reass_n);
  vlib_cli_output (vm,
                   "Maximum configured concurrent shallow virtual IP4 reassemblies per worker-thread: %lu\n",
                   (long unsigned) rm->max_reass_n);
  vlib_cli_output (vm,
                   "Maximum configured shallow virtual IP4 reassembly timeout: %lums\n",
                   (long unsigned) rm->timeout_ms);
  vlib_cli_output (vm,
                   "Maximum configured shallow virtual IP4 reassembly expire walk interval: %lums\n",
                   (long unsigned) rm->expire_walk_interval_ms);
  return 0;
}

/* *INDENT-OFF* */
VLIB_CLI_COMMAND (show_ip4_sv_reass_cmd, static) = {
    .path = "show ip4-sv-reassembly",
    .short_help = "show ip4-sv-reassembly [details]",
    .function = show_ip4_reass,
};
/* *INDENT-ON* */

#ifndef CLIB_MARCH_VARIANT
vnet_api_error_t
ip4_sv_reass_enable_disable (u32 sw_if_index, u8 enable_disable)
{
  return ip4_sv_reass_enable_disable_with_refcnt (sw_if_index,
                                                  enable_disable);
}
#endif /* CLIB_MARCH_VARIANT */


#define foreach_ip4_sv_reass_handoff_error                       \
_(CONGESTION_DROP, "congestion drop")


typedef enum
{
#define _(sym,str) IP4_SV_REASSEMBLY_HANDOFF_ERROR_##sym,
  foreach_ip4_sv_reass_handoff_error
#undef _
    IP4_SV_REASSEMBLY_HANDOFF_N_ERROR,
} ip4_sv_reass_handoff_error_t;

static char *ip4_sv_reass_handoff_error_strings[] = {
#define _(sym,string) string,
  foreach_ip4_sv_reass_handoff_error
#undef _
};

typedef struct
{
  u32 next_worker_index;
} ip4_sv_reass_handoff_trace_t;

static u8 *
format_ip4_sv_reass_handoff_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 *);
  ip4_sv_reass_handoff_trace_t *t =
    va_arg (*args, ip4_sv_reass_handoff_trace_t *);

  s =
    format (s, "ip4-sv-reassembly-handoff: next-worker %d",
            t->next_worker_index);

  return s;
}

always_inline uword
ip4_sv_reass_handoff_node_inline (vlib_main_t * vm,
                                  vlib_node_runtime_t * node,
                                  vlib_frame_t * frame, bool is_feature)
{
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;

  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
  u32 n_enq, n_left_from, *from;
  u16 thread_indices[VLIB_FRAME_SIZE], *ti;
  u32 fq_index;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  vlib_get_buffers (vm, from, bufs, n_left_from);

  b = bufs;
  ti = thread_indices;

  fq_index = (is_feature) ? rm->fq_feature_index : rm->fq_index;

  while (n_left_from > 0)
    {
      ti[0] = vnet_buffer (b[0])->ip.reass.owner_thread_index;

      if (PREDICT_FALSE
          ((node->flags & VLIB_NODE_FLAG_TRACE)
           && (b[0]->flags & VLIB_BUFFER_IS_TRACED)))
        {
          ip4_sv_reass_handoff_trace_t *t =
            vlib_add_trace (vm, node, b[0], sizeof (*t));
          t->next_worker_index = ti[0];
        }

      n_left_from -= 1;
      ti += 1;
      b += 1;
    }
  n_enq =
    vlib_buffer_enqueue_to_thread (vm, fq_index, from, thread_indices,
                                   frame->n_vectors, 1);

  if (n_enq < frame->n_vectors)
    vlib_node_increment_counter (vm, node->node_index,
                                 IP4_SV_REASSEMBLY_HANDOFF_ERROR_CONGESTION_DROP,
                                 frame->n_vectors - n_enq);
  return frame->n_vectors;
}

VLIB_NODE_FN (ip4_sv_reass_handoff_node) (vlib_main_t * vm,
                                          vlib_node_runtime_t * node,
                                          vlib_frame_t * frame)
{
  return ip4_sv_reass_handoff_node_inline (vm, node, frame,
                                           false /* is_feature */ );
}


/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip4_sv_reass_handoff_node) = {
  .name = "ip4-sv-reassembly-handoff",
  .vector_size = sizeof (u32),
  .n_errors = ARRAY_LEN(ip4_sv_reass_handoff_error_strings),
  .error_strings = ip4_sv_reass_handoff_error_strings,
  .format_trace = format_ip4_sv_reass_handoff_trace,

  .n_next_nodes = 1,

  .next_nodes = {
    [0] = "error-drop",
  },
};
/* *INDENT-ON* */


/* *INDENT-OFF* */
VLIB_NODE_FN (ip4_sv_reass_feature_handoff_node) (vlib_main_t * vm,
                                                    vlib_node_runtime_t *
                                                    node,
                                                    vlib_frame_t * frame)
{
  return ip4_sv_reass_handoff_node_inline (vm, node, frame,
                                             true /* is_feature */ );
}
/* *INDENT-ON* */


/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip4_sv_reass_feature_handoff_node) = {
  .name = "ip4-sv-reass-feature-hoff",
  .vector_size = sizeof (u32),
  .n_errors = ARRAY_LEN(ip4_sv_reass_handoff_error_strings),
  .error_strings = ip4_sv_reass_handoff_error_strings,
  .format_trace = format_ip4_sv_reass_handoff_trace,

  .n_next_nodes = 1,

  .next_nodes = {
    [0] = "error-drop",
  },
};
/* *INDENT-ON* */

#ifndef CLIB_MARCH_VARIANT
int
ip4_sv_reass_enable_disable_with_refcnt (u32 sw_if_index, int is_enable)
{
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;
  vec_validate (rm->feature_use_refcount_per_intf, sw_if_index);
  if (is_enable)
    {
      if (!rm->feature_use_refcount_per_intf[sw_if_index])
        {
          ++rm->feature_use_refcount_per_intf[sw_if_index];
          return vnet_feature_enable_disable ("ip4-unicast",
                                              "ip4-sv-reassembly-feature",
                                              sw_if_index, 1, 0, 0);
        }
      ++rm->feature_use_refcount_per_intf[sw_if_index];
    }
  else
    {
      if (rm->feature_use_refcount_per_intf[sw_if_index])
        --rm->feature_use_refcount_per_intf[sw_if_index];
      if (!rm->feature_use_refcount_per_intf[sw_if_index])
        return vnet_feature_enable_disable ("ip4-unicast",
                                            "ip4-sv-reassembly-feature",
                                            sw_if_index, 0, 0, 0);
    }
  return 0;
}

uword
ip4_sv_reass_custom_register_next_node (uword node_index)
{
  return vlib_node_add_next (vlib_get_main (), ip4_sv_reass_custom_node.index,
                             node_index);
}

int
ip4_sv_reass_output_enable_disable_with_refcnt (u32 sw_if_index,
                                                int is_enable)
{
  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;
  vec_validate (rm->output_feature_use_refcount_per_intf, sw_if_index);
  if (is_enable)
    {
      if (!rm->output_feature_use_refcount_per_intf[sw_if_index])
        {
          ++rm->output_feature_use_refcount_per_intf[sw_if_index];
          return vnet_feature_enable_disable ("ip4-output",
                                              "ip4-sv-reassembly-output-feature",
                                              sw_if_index, 1, 0, 0);
        }
      ++rm->output_feature_use_refcount_per_intf[sw_if_index];
    }
  else
    {
      if (rm->output_feature_use_refcount_per_intf[sw_if_index])
        --rm->output_feature_use_refcount_per_intf[sw_if_index];
      if (!rm->output_feature_use_refcount_per_intf[sw_if_index])
        return vnet_feature_enable_disable ("ip4-output",
                                            "ip4-sv-reassembly-output-feature",
                                            sw_if_index, 0, 0, 0);
    }
  return 0;
}
#endif

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