lb.c

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/*
 * 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.
 */

#include <lb/lb.h>
#include <vnet/plugin/plugin.h>
#include <vpp/app/version.h>
#include <vnet/api_errno.h>
#include <vnet/udp/udp.h>
#include <vppinfra/lock.h>

//GC runs at most once every so many seconds
#define LB_GARBAGE_RUN 60

//After so many seconds. It is assumed that inter-core race condition will not occur.
#define LB_CONCURRENCY_TIMEOUT 10

// FIB source for adding routes
static fib_source_t lb_fib_src;

lb_main_t lb_main;

#define lb_get_writer_lock() clib_spinlock_lock (&lb_main.writer_lock)
#define lb_put_writer_lock() clib_spinlock_unlock (&lb_main.writer_lock)

static void lb_as_stack (lb_as_t *as);


const static char * const lb_dpo_gre4_ip4[] = { "lb4-gre4" , NULL };
const static char * const lb_dpo_gre4_ip6[] = { "lb6-gre4" , NULL };
const static char* const * const lb_dpo_gre4_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP4]  = lb_dpo_gre4_ip4,
        [DPO_PROTO_IP6]  = lb_dpo_gre4_ip6,
    };

const static char * const lb_dpo_gre6_ip4[] = { "lb4-gre6" , NULL };
const static char * const lb_dpo_gre6_ip6[] = { "lb6-gre6" , NULL };
const static char* const * const lb_dpo_gre6_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP4]  = lb_dpo_gre6_ip4,
        [DPO_PROTO_IP6]  = lb_dpo_gre6_ip6,
    };

const static char * const lb_dpo_gre4_ip4_port[] = { "lb4-gre4-port" , NULL };
const static char * const lb_dpo_gre4_ip6_port[] = { "lb6-gre4-port" , NULL };
const static char* const * const lb_dpo_gre4_port_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP4]  = lb_dpo_gre4_ip4_port,
        [DPO_PROTO_IP6]  = lb_dpo_gre4_ip6_port,
    };

const static char * const lb_dpo_gre6_ip4_port[] = { "lb4-gre6-port" , NULL };
const static char * const lb_dpo_gre6_ip6_port[] = { "lb6-gre6-port" , NULL };
const static char* const * const lb_dpo_gre6_port_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP4]  = lb_dpo_gre6_ip4_port,
        [DPO_PROTO_IP6]  = lb_dpo_gre6_ip6_port,
    };

const static char * const lb_dpo_l3dsr_ip4[] = {"lb4-l3dsr" , NULL};
const static char* const * const lb_dpo_l3dsr_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP4]  = lb_dpo_l3dsr_ip4,
    };

const static char * const lb_dpo_l3dsr_ip4_port[] = {"lb4-l3dsr-port" , NULL};
const static char* const * const lb_dpo_l3dsr_port_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP4]  = lb_dpo_l3dsr_ip4_port,
    };

const static char * const lb_dpo_nat4_ip4_port[] = { "lb4-nat4-port" , NULL };
const static char* const * const lb_dpo_nat4_port_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP4]  = lb_dpo_nat4_ip4_port,
    };

const static char * const lb_dpo_nat6_ip6_port[] = { "lb6-nat6-port" , NULL };
const static char* const * const lb_dpo_nat6_port_nodes[DPO_PROTO_NUM] =
    {
        [DPO_PROTO_IP6]  = lb_dpo_nat6_ip6_port,
    };

u32 lb_hash_time_now(vlib_main_t * vm)
{
  return (u32) (vlib_time_now(vm) + 10000);
}

u8 *format_lb_main (u8 * s, va_list * args)
{
  vlib_thread_main_t *tm = vlib_get_thread_main();
  lb_main_t *lbm = &lb_main;
  s = format(s, "lb_main");
  s = format(s, " ip4-src-address: %U \n", format_ip4_address, &lbm->ip4_src_address);
  s = format(s, " ip6-src-address: %U \n", format_ip6_address, &lbm->ip6_src_address);
  s = format(s, " #vips: %u\n", pool_elts(lbm->vips));
  s = format(s, " #ass: %u\n", pool_elts(lbm->ass) - 1);

  u32 thread_index;
  for(thread_index = 0; thread_index < tm->n_vlib_mains; thread_index++ ) {
    lb_hash_t *h = lbm->per_cpu[thread_index].sticky_ht;
    if (h) {
      s = format(s, "core %d\n", thread_index);
      s = format(s, "  timeout: %ds\n", h->timeout);
      s = format(s, "  usage: %d / %d\n", lb_hash_elts(h, lb_hash_time_now(vlib_get_main())),  lb_hash_size(h));
    }
  }

  return s;
}

static char *lb_vip_type_strings[] = {
    [LB_VIP_TYPE_IP6_GRE6] = "ip6-gre6",
    [LB_VIP_TYPE_IP6_GRE4] = "ip6-gre4",
    [LB_VIP_TYPE_IP4_GRE6] = "ip4-gre6",
    [LB_VIP_TYPE_IP4_GRE4] = "ip4-gre4",
    [LB_VIP_TYPE_IP4_L3DSR] = "ip4-l3dsr",
    [LB_VIP_TYPE_IP4_NAT4] = "ip4-nat4",
    [LB_VIP_TYPE_IP6_NAT6] = "ip6-nat6",
};

u8 *format_lb_vip_type (u8 * s, va_list * args)
{
  lb_vip_type_t vipt = va_arg (*args, lb_vip_type_t);
  u32 i;
  for (i=0; i<LB_VIP_N_TYPES; i++)
    if (vipt == i)
      return format(s, lb_vip_type_strings[i]);
  return format(s, "_WRONG_TYPE_");
}

uword unformat_lb_vip_type (unformat_input_t * input, va_list * args)
{
  lb_vip_type_t *vipt = va_arg (*args, lb_vip_type_t *);
  u32 i;
  for (i=0; i<LB_VIP_N_TYPES; i++)
    if (unformat(input, lb_vip_type_strings[i])) {
      *vipt = i;
      return 1;
    }
  return 0;
}

u8 *format_lb_vip (u8 * s, va_list * args)
{
  lb_vip_t *vip = va_arg (*args, lb_vip_t *);
  s = format(s, "%U %U new_size:%u #as:%u%s",
             format_lb_vip_type, vip->type,
             format_ip46_prefix, &vip->prefix, vip->plen, IP46_TYPE_ANY,
             vip->new_flow_table_mask + 1,
             pool_elts(vip->as_indexes),
             (vip->flags & LB_VIP_FLAGS_USED)?"":" removed");

  if (vip->port != 0)
    {
      s = format(s, "  protocol:%u port:%u ", vip->protocol, vip->port);
    }

  if (vip->type == LB_VIP_TYPE_IP4_L3DSR)
    {
      s = format(s, "  dscp:%u", vip->encap_args.dscp);
    }
  else if ((vip->type == LB_VIP_TYPE_IP4_NAT4)
          || (vip->type == LB_VIP_TYPE_IP6_NAT6))
    {
      s = format (s, " type:%s port:%u target_port:%u",
         (vip->encap_args.srv_type == LB_SRV_TYPE_CLUSTERIP)?"clusterip":
             "nodeport",
         ntohs(vip->port), ntohs(vip->encap_args.target_port));
    }

  return s;
}

u8 *format_lb_as (u8 * s, va_list * args)
{
  lb_as_t *as = va_arg (*args, lb_as_t *);
  return format(s, "%U %s", format_ip46_address,
                &as->address, IP46_TYPE_ANY,
                (as->flags & LB_AS_FLAGS_USED)?"used":"removed");
}

u8 *format_lb_vip_detailed (u8 * s, va_list * args)
{
  lb_main_t *lbm = &lb_main;
  lb_vip_t *vip = va_arg (*args, lb_vip_t *);
  u32 indent = format_get_indent (s);

  s = format(s, "%U %U [%lu] %U%s\n"
                   "%U  new_size:%u\n",
                  format_white_space, indent,
                  format_lb_vip_type, vip->type,
                  vip - lbm->vips,
                  format_ip46_prefix, &vip->prefix, (u32) vip->plen, IP46_TYPE_ANY,
                  (vip->flags & LB_VIP_FLAGS_USED)?"":" removed",
                  format_white_space, indent,
                  vip->new_flow_table_mask + 1);

  if (vip->port != 0)
    {
      s = format(s, "%U  protocol:%u port:%u\n",
                 format_white_space, indent,
                 vip->protocol, vip->port);
    }

  if (vip->type == LB_VIP_TYPE_IP4_L3DSR)
    {
      s = format(s, "%U  dscp:%u\n",
                    format_white_space, indent,
                    vip->encap_args.dscp);
    }
  else if ((vip->type == LB_VIP_TYPE_IP4_NAT4)
          || (vip->type == LB_VIP_TYPE_IP6_NAT6))
    {
      s = format (s, "%U  type:%s port:%u target_port:%u",
         format_white_space, indent,
         (vip->encap_args.srv_type == LB_SRV_TYPE_CLUSTERIP)?"clusterip":
             "nodeport",
         ntohs(vip->port), ntohs(vip->encap_args.target_port));
    }

  //Print counters
  s = format(s, "%U  counters:\n",
             format_white_space, indent);
  u32 i;
  for (i=0; i<LB_N_VIP_COUNTERS; i++)
    s = format(s, "%U    %s: %Lu\n",
               format_white_space, indent,
               lbm->vip_counters[i].name,
               vlib_get_simple_counter(&lbm->vip_counters[i], vip - lbm->vips));


  s = format(s, "%U  #as:%u\n",
             format_white_space, indent,
             pool_elts(vip->as_indexes));

  //Let's count the buckets for each AS
  u32 *count = 0;
  vec_validate(count, pool_len(lbm->ass)); //Possibly big alloc for not much...
  lb_new_flow_entry_t *nfe;
  vec_foreach(nfe, vip->new_flow_table)
    count[nfe->as_index]++;

  lb_as_t *as;
  u32 *as_index;
  pool_foreach(as_index, vip->as_indexes, {
      as = &lbm->ass[*as_index];
      s = format(s, "%U    %U %u buckets   %Lu flows  dpo:%u %s\n",
                   format_white_space, indent,
                   format_ip46_address, &as->address, IP46_TYPE_ANY,
                   count[as - lbm->ass],
                   vlib_refcount_get(&lbm->as_refcount, as - lbm->ass),
                   as->dpo.dpoi_index,
                   (as->flags & LB_AS_FLAGS_USED)?"used":" removed");
  });

  vec_free(count);
  return s;
}

typedef struct {
  u32 as_index;
  u32 last;
  u32 skip;
} lb_pseudorand_t;

static int lb_pseudorand_compare(void *a, void *b)
{
  lb_as_t *asa, *asb;
  lb_main_t *lbm = &lb_main;
  asa = &lbm->ass[((lb_pseudorand_t *)a)->as_index];
  asb = &lbm->ass[((lb_pseudorand_t *)b)->as_index];
  return memcmp(&asa->address, &asb->address, sizeof(asb->address));
}

static void lb_vip_garbage_collection(lb_vip_t *vip)
{
  lb_main_t *lbm = &lb_main;
  lb_snat4_key_t m_key4;
  clib_bihash_kv_8_8_t kv4, value4;
  lb_snat6_key_t m_key6;
  clib_bihash_kv_24_8_t kv6, value6;
  lb_snat_mapping_t *m = 0;
  CLIB_SPINLOCK_ASSERT_LOCKED (&lbm->writer_lock);

  u32 now = (u32) vlib_time_now(vlib_get_main());
  if (!clib_u32_loop_gt(now, vip->last_garbage_collection + LB_GARBAGE_RUN))
    return;

  vip->last_garbage_collection = now;
  lb_as_t *as;
  u32 *as_index;
  pool_foreach(as_index, vip->as_indexes, {
      as = &lbm->ass[*as_index];
      if (!(as->flags & LB_AS_FLAGS_USED) && //Not used
          clib_u32_loop_gt(now, as->last_used + LB_CONCURRENCY_TIMEOUT) &&
          (vlib_refcount_get(&lbm->as_refcount, as - lbm->ass) == 0))
        { //Not referenced

          if (lb_vip_is_nat4_port(vip)) {
              m_key4.addr = as->address.ip4;
              m_key4.port = vip->encap_args.target_port;
              m_key4.protocol = 0;
              m_key4.fib_index = 0;

              kv4.key = m_key4.as_u64;
              if(!clib_bihash_search_8_8(&lbm->mapping_by_as4, &kv4, &value4))
                m = pool_elt_at_index (lbm->snat_mappings, value4.value);
              ASSERT (m);

              kv4.value = m - lbm->snat_mappings;
              clib_bihash_add_del_8_8(&lbm->mapping_by_as4, &kv4, 0);
              pool_put (lbm->snat_mappings, m);
          } else if (lb_vip_is_nat6_port(vip)) {
              m_key6.addr.as_u64[0] = as->address.ip6.as_u64[0];
              m_key6.addr.as_u64[1] = as->address.ip6.as_u64[1];
              m_key6.port = vip->encap_args.target_port;
              m_key6.protocol = 0;
              m_key6.fib_index = 0;

              kv6.key[0] = m_key6.as_u64[0];
              kv6.key[1] = m_key6.as_u64[1];
              kv6.key[2] = m_key6.as_u64[2];

              if (!clib_bihash_search_24_8 (&lbm->mapping_by_as6, &kv6, &value6))
                m = pool_elt_at_index (lbm->snat_mappings, value6.value);
              ASSERT (m);

              kv6.value = m - lbm->snat_mappings;
              clib_bihash_add_del_24_8(&lbm->mapping_by_as6, &kv6, 0);
              pool_put (lbm->snat_mappings, m);
          }
          fib_entry_child_remove(as->next_hop_fib_entry_index,
                                as->next_hop_child_index);
          fib_table_entry_delete_index(as->next_hop_fib_entry_index,
                                       FIB_SOURCE_RR);
          as->next_hop_fib_entry_index = FIB_NODE_INDEX_INVALID;

          pool_put(vip->as_indexes, as_index);
          pool_put(lbm->ass, as);
        }
  });
}

void lb_garbage_collection()
{
  lb_main_t *lbm = &lb_main;
  lb_get_writer_lock();
  lb_vip_t *vip;
  u32 *to_be_removed_vips = 0, *i;
  pool_foreach(vip, lbm->vips, {
      lb_vip_garbage_collection(vip);

      if (!(vip->flags & LB_VIP_FLAGS_USED) &&
          (pool_elts(vip->as_indexes) == 0)) {
        vec_add1(to_be_removed_vips, vip - lbm->vips);
      }
  });

  vec_foreach(i, to_be_removed_vips) {
    vip = &lbm->vips[*i];
    pool_put(lbm->vips, vip);
    pool_free(vip->as_indexes);
  }

  vec_free(to_be_removed_vips);
  lb_put_writer_lock();
}

static void lb_vip_update_new_flow_table(lb_vip_t *vip)
{
  lb_main_t *lbm = &lb_main;
  lb_new_flow_entry_t *old_table;
  u32 i, *as_index;
  lb_new_flow_entry_t *new_flow_table = 0;
  lb_as_t *as;
  lb_pseudorand_t *pr, *sort_arr = 0;

  CLIB_SPINLOCK_ASSERT_LOCKED (&lbm->writer_lock); // We must have the lock

  //Check if some AS is configured or not
  i = 0;
  pool_foreach(as_index, vip->as_indexes, {
      as = &lbm->ass[*as_index];
      if (as->flags & LB_AS_FLAGS_USED) { //Not used anymore
        i = 1;
        goto out; //Not sure 'break' works in this macro-loop
      }
  });

out:
  if (i == 0) {
    //Only the default. i.e. no AS
    vec_validate(new_flow_table, vip->new_flow_table_mask);
    for (i=0; i<vec_len(new_flow_table); i++)
      new_flow_table[i].as_index = 0;

    goto finished;
  }

  //First, let's sort the ASs
  vec_alloc(sort_arr, pool_elts(vip->as_indexes));

  i = 0;
  pool_foreach(as_index, vip->as_indexes, {
      as = &lbm->ass[*as_index];
      if (!(as->flags & LB_AS_FLAGS_USED)) //Not used anymore
        continue;

      sort_arr[i].as_index = as - lbm->ass;
      i++;
  });
  _vec_len(sort_arr) = i;

  vec_sort_with_function(sort_arr, lb_pseudorand_compare);

  //Now let's pseudo-randomly generate permutations
  vec_foreach(pr, sort_arr) {
    lb_as_t *as = &lbm->ass[pr->as_index];

    u64 seed = clib_xxhash(as->address.as_u64[0] ^
                           as->address.as_u64[1]);
    /* We have 2^n buckets.
     * skip must be prime with 2^n.
     * So skip must be odd.
     * MagLev actually state that M should be prime,
     * but this has a big computation cost (% operation).
     * Using 2^n is more better (& operation).
     */
    pr->skip = ((seed & 0xffffffff) | 1) & vip->new_flow_table_mask;
    pr->last = (seed >> 32) & vip->new_flow_table_mask;
  }

  //Let's create a new flow table
  vec_validate(new_flow_table, vip->new_flow_table_mask);
  for (i=0; i<vec_len(new_flow_table); i++)
    new_flow_table[i].as_index = 0;

  u32 done = 0;
  while (1) {
    vec_foreach(pr, sort_arr) {
      while (1) {
        u32 last = pr->last;
        pr->last = (pr->last + pr->skip) & vip->new_flow_table_mask;
        if (new_flow_table[last].as_index == 0) {
          new_flow_table[last].as_index = pr->as_index;
          break;
        }
      }
      done++;
      if (done == vec_len(new_flow_table))
        goto finished;
    }
  }

finished:
  vec_free(sort_arr);

  old_table = vip->new_flow_table;
  vip->new_flow_table = new_flow_table;
  vec_free(old_table);
}

int lb_conf(ip4_address_t *ip4_address, ip6_address_t *ip6_address,
           u32 per_cpu_sticky_buckets, u32 flow_timeout)
{
  lb_main_t *lbm = &lb_main;

  if (!is_pow2(per_cpu_sticky_buckets))
    return VNET_API_ERROR_INVALID_MEMORY_SIZE;

  lb_get_writer_lock(); //Not exactly necessary but just a reminder that it exists for my future self
  lbm->ip4_src_address = *ip4_address;
  lbm->ip6_src_address = *ip6_address;
  lbm->per_cpu_sticky_buckets = per_cpu_sticky_buckets;
  lbm->flow_timeout = flow_timeout;
  lb_put_writer_lock();
  return 0;
}



static
int lb_vip_port_find_index(ip46_address_t *prefix, u8 plen,
                           u8 protocol, u16 port,
                           lb_lkp_type_t lkp_type,
                           u32 *vip_index)
{
  lb_main_t *lbm = &lb_main;
  lb_vip_t *vip;
  /* This must be called with the lock owned */
  CLIB_SPINLOCK_ASSERT_LOCKED (&lbm->writer_lock);
  ip46_prefix_normalize(prefix, plen);
  pool_foreach(vip, lbm->vips, {
      if ((vip->flags & LB_AS_FLAGS_USED) &&
          vip->plen == plen &&
          vip->prefix.as_u64[0] == prefix->as_u64[0] &&
          vip->prefix.as_u64[1] == prefix->as_u64[1])
        {
          if((lkp_type == LB_LKP_SAME_IP_PORT &&
               vip->protocol == protocol &&
               vip->port == port) ||
             (lkp_type == LB_LKP_ALL_PORT_IP &&
               vip->port == 0) ||
             (lkp_type == LB_LKP_DIFF_IP_PORT &&
                (vip->protocol != protocol ||
                vip->port != port) ) )
            {
              *vip_index = vip - lbm->vips;
              return 0;
            }
        }
  });
  return VNET_API_ERROR_NO_SUCH_ENTRY;
}

static
int lb_vip_port_find_index_with_lock(ip46_address_t *prefix, u8 plen,
                                     u8 protocol, u16 port, u32 *vip_index)
{
  return lb_vip_port_find_index(prefix, plen, protocol, port,
                                LB_LKP_SAME_IP_PORT, vip_index);
}

static
int lb_vip_port_find_all_port_vip(ip46_address_t *prefix, u8 plen,
                                  u32 *vip_index)
{
  return lb_vip_port_find_index(prefix, plen, ~0, 0,
                                LB_LKP_ALL_PORT_IP, vip_index);
}

/* Find out per-port-vip entry with different protocol and port */
static
int lb_vip_port_find_diff_port(ip46_address_t *prefix, u8 plen,
                               u8 protocol, u16 port, u32 *vip_index)
{
  return lb_vip_port_find_index(prefix, plen, protocol, port,
                                LB_LKP_DIFF_IP_PORT, vip_index);
}

int lb_vip_find_index(ip46_address_t *prefix, u8 plen, u8 protocol,
                      u16 port, u32 *vip_index)
{
  int ret;
  lb_get_writer_lock();
  ret = lb_vip_port_find_index_with_lock(prefix, plen,
                                         protocol, port, vip_index);
  lb_put_writer_lock();
  return ret;
}

static int lb_as_find_index_vip(lb_vip_t *vip, ip46_address_t *address, u32 *as_index)
{
  lb_main_t *lbm = &lb_main;
  /* This must be called with the lock owned */
  CLIB_SPINLOCK_ASSERT_LOCKED (&lbm->writer_lock);
  lb_as_t *as;
  u32 *asi;
  pool_foreach(asi, vip->as_indexes, {
      as = &lbm->ass[*asi];
      if (as->vip_index == (vip - lbm->vips) &&
          as->address.as_u64[0] == address->as_u64[0] &&
          as->address.as_u64[1] == address->as_u64[1])
      {
        *as_index = as - lbm->ass;
        return 0;
      }
  });
  return -1;
}

int lb_vip_add_ass(u32 vip_index, ip46_address_t *addresses, u32 n)
{
  lb_main_t *lbm = &lb_main;
  lb_get_writer_lock();
  lb_vip_t *vip;
  if (!(vip = lb_vip_get_by_index(vip_index))) {
    lb_put_writer_lock();
    return VNET_API_ERROR_NO_SUCH_ENTRY;
  }

  ip46_type_t type = lb_encap_is_ip4(vip)?IP46_TYPE_IP4:IP46_TYPE_IP6;
  u32 *to_be_added = 0;
  u32 *to_be_updated = 0;
  u32 i;
  u32 *ip;
  lb_snat_mapping_t *m;

  //Sanity check
  while (n--) {

    if (!lb_as_find_index_vip(vip, &addresses[n], &i)) {
      if (lbm->ass[i].flags & LB_AS_FLAGS_USED) {
        vec_free(to_be_added);
        vec_free(to_be_updated);
        lb_put_writer_lock();
        return VNET_API_ERROR_VALUE_EXIST;
      }
      vec_add1(to_be_updated, i);
      goto next;
    }

    if (ip46_address_type(&addresses[n]) != type) {
      vec_free(to_be_added);
      vec_free(to_be_updated);
      lb_put_writer_lock();
      return VNET_API_ERROR_INVALID_ADDRESS_FAMILY;
    }

    if (n) {
      u32 n2 = n;
      while(n2--) //Check for duplicates
        if (addresses[n2].as_u64[0] == addresses[n].as_u64[0] &&
            addresses[n2].as_u64[1] == addresses[n].as_u64[1])
          goto next;
    }

    vec_add1(to_be_added, n);

next:
    continue;
  }

  //Update reused ASs
  vec_foreach(ip, to_be_updated) {
    lbm->ass[*ip].flags = LB_AS_FLAGS_USED;
  }
  vec_free(to_be_updated);

  //Create those who have to be created
  vec_foreach(ip, to_be_added) {
    lb_as_t *as;
    u32 *as_index;
    pool_get(lbm->ass, as);
    as->address = addresses[*ip];
    as->flags = LB_AS_FLAGS_USED;
    as->vip_index = vip_index;
    pool_get(vip->as_indexes, as_index);
    *as_index = as - lbm->ass;

    /*
     * become a child of the FIB entry
     * so we are informed when its forwarding changes
     */
    fib_prefix_t nh = {};
    if (lb_encap_is_ip4(vip)) {
        nh.fp_addr.ip4 = as->address.ip4;
        nh.fp_len = 32;
        nh.fp_proto = FIB_PROTOCOL_IP4;
    } else {
        nh.fp_addr.ip6 = as->address.ip6;
        nh.fp_len = 128;
        nh.fp_proto = FIB_PROTOCOL_IP6;
    }

    as->next_hop_fib_entry_index =
        fib_table_entry_special_add(0,
                                    &nh,
                                    FIB_SOURCE_RR,
                                    FIB_ENTRY_FLAG_NONE);
    as->next_hop_child_index =
        fib_entry_child_add(as->next_hop_fib_entry_index,
                            lbm->fib_node_type,
                            as - lbm->ass);

    lb_as_stack(as);

    if ( lb_vip_is_nat4_port(vip) || lb_vip_is_nat6_port(vip) )
      {
        /* Add SNAT static mapping */
        pool_get (lbm->snat_mappings, m);
        clib_memset (m, 0, sizeof (*m));
        if (lb_vip_is_nat4_port(vip)) {
            lb_snat4_key_t m_key4;
            clib_bihash_kv_8_8_t kv4;
            m_key4.addr = as->address.ip4;
            m_key4.port = vip->encap_args.target_port;
            m_key4.protocol = 0;
            m_key4.fib_index = 0;

            if (vip->encap_args.srv_type == LB_SRV_TYPE_CLUSTERIP)
              {
                m->src_ip.ip4 = vip->prefix.ip4;
              }
            else if (vip->encap_args.srv_type == LB_SRV_TYPE_NODEPORT)
              {
                m->src_ip.ip4 = lbm->ip4_src_address;
              }
            m->src_ip_is_ipv6 = 0;
            m->as_ip.ip4 = as->address.ip4;
            m->as_ip_is_ipv6 = 0;
            m->src_port = vip->port;
            m->target_port = vip->encap_args.target_port;
            m->vrf_id = 0;
            m->fib_index = 0;

            kv4.key = m_key4.as_u64;
            kv4.value = m - lbm->snat_mappings;
            clib_bihash_add_del_8_8(&lbm->mapping_by_as4, &kv4, 1);
        } else {
            lb_snat6_key_t m_key6;
            clib_bihash_kv_24_8_t kv6;
            m_key6.addr.as_u64[0] = as->address.ip6.as_u64[0];
            m_key6.addr.as_u64[1] = as->address.ip6.as_u64[1];
            m_key6.port = vip->encap_args.target_port;
            m_key6.protocol = 0;
            m_key6.fib_index = 0;

            if (vip->encap_args.srv_type == LB_SRV_TYPE_CLUSTERIP)
              {
                m->src_ip.ip6.as_u64[0] = vip->prefix.ip6.as_u64[0];
                m->src_ip.ip6.as_u64[1] = vip->prefix.ip6.as_u64[1];
              }
            else if (vip->encap_args.srv_type == LB_SRV_TYPE_NODEPORT)
              {
                m->src_ip.ip6.as_u64[0] = lbm->ip6_src_address.as_u64[0];
                m->src_ip.ip6.as_u64[1] = lbm->ip6_src_address.as_u64[1];
              }
            m->src_ip_is_ipv6 = 1;
            m->as_ip.ip6.as_u64[0] = as->address.ip6.as_u64[0];
            m->as_ip.ip6.as_u64[1] = as->address.ip6.as_u64[1];
            m->as_ip_is_ipv6 = 1;
            m->src_port = vip->port;
            m->target_port = vip->encap_args.target_port;
            m->vrf_id = 0;
            m->fib_index = 0;

            kv6.key[0] = m_key6.as_u64[0];
            kv6.key[1] = m_key6.as_u64[1];
            kv6.key[2] = m_key6.as_u64[2];
            kv6.value = m - lbm->snat_mappings;
            clib_bihash_add_del_24_8(&lbm->mapping_by_as6, &kv6, 1);
        }
      }
  }
  vec_free(to_be_added);

  //Recompute flows
  lb_vip_update_new_flow_table(vip);

  //Garbage collection maybe
  lb_vip_garbage_collection(vip);

  lb_put_writer_lock();
  return 0;
}

int
lb_flush_vip_as (u32 vip_index, u32 as_index)
{
  u32 thread_index;
  vlib_thread_main_t *tm = vlib_get_thread_main();
  lb_main_t *lbm = &lb_main;

  for(thread_index = 0; thread_index < tm->n_vlib_mains; thread_index++ ) {
    lb_hash_t *h = lbm->per_cpu[thread_index].sticky_ht;
    if (h != NULL) {
        u32 i;
        lb_hash_bucket_t *b;

        lb_hash_foreach_entry(h, b, i) {
          if ((vip_index == ~0)
              || ((b->vip[i] == vip_index) && (as_index == ~0))
              || ((b->vip[i] == vip_index) && (b->value[i] == as_index)))
            {
              vlib_refcount_add(&lbm->as_refcount, thread_index, b->value[i], -1);
              vlib_refcount_add(&lbm->as_refcount, thread_index, 0, 1);
              b->vip[i] = ~0;
              b->value[i] = 0;
            }
        }
        if (vip_index == ~0)
          {
            lb_hash_free(h);
            lbm->per_cpu[thread_index].sticky_ht = 0;
          }
      }
    }

  return 0;
}

int lb_vip_del_ass_withlock(u32 vip_index, ip46_address_t *addresses, u32 n,
                            u8 flush)
{
  lb_main_t *lbm = &lb_main;
  u32 now = (u32) vlib_time_now(vlib_get_main());
  u32 *ip = 0;
  u32 as_index = 0;

  lb_vip_t *vip;
  if (!(vip = lb_vip_get_by_index(vip_index))) {
    return VNET_API_ERROR_NO_SUCH_ENTRY;
  }

  u32 *indexes = NULL;
  while (n--) {
    if (lb_as_find_index_vip(vip, &addresses[n], &as_index)) {
      vec_free(indexes);
      return VNET_API_ERROR_NO_SUCH_ENTRY;
    }

    if (n) { //Check for duplicates
      u32 n2 = n - 1;
      while(n2--) {
        if (addresses[n2].as_u64[0] == addresses[n].as_u64[0] &&
            addresses[n2].as_u64[1] == addresses[n].as_u64[1])
          goto next;
      }
    }

    vec_add1(indexes, as_index);
next:
  continue;
  }

  //Garbage collection maybe
  lb_vip_garbage_collection(vip);

  if (indexes != NULL) {
    vec_foreach(ip, indexes) {
      lbm->ass[*ip].flags &= ~LB_AS_FLAGS_USED;
      lbm->ass[*ip].last_used = now;

      if(flush)
        {
          /* flush flow table for deleted ASs*/
          lb_flush_vip_as(vip_index, *ip);
        }
    }

    //Recompute flows
    lb_vip_update_new_flow_table(vip);
  }

  vec_free(indexes);
  return 0;
}

int lb_vip_del_ass(u32 vip_index, ip46_address_t *addresses, u32 n, u8 flush)
{
  lb_get_writer_lock();
  int ret = lb_vip_del_ass_withlock(vip_index, addresses, n, flush);
  lb_put_writer_lock();

  return ret;
}

static int
lb_vip_prefix_index_alloc (lb_main_t *lbm)
{
  /*
   * Check for dynamically allocated instance number.
   */
  u32 bit;

  bit = clib_bitmap_first_clear (lbm->vip_prefix_indexes);

  lbm->vip_prefix_indexes = clib_bitmap_set(lbm->vip_prefix_indexes, bit, 1);

  return bit;
}

static int
lb_vip_prefix_index_free (lb_main_t *lbm, u32 instance)
{

  if (clib_bitmap_get (lbm->vip_prefix_indexes, instance) == 0)
    {
      return -1;
    }

  lbm->vip_prefix_indexes = clib_bitmap_set (lbm->vip_prefix_indexes,
                                             instance, 0);

  return 0;
}

/**
 * Add the VIP adjacency to the ip4 or ip6 fib
 */
static void lb_vip_add_adjacency(lb_main_t *lbm, lb_vip_t *vip,
                                 u32 *vip_prefix_index)
{
  dpo_proto_t proto = 0;
  dpo_type_t dpo_type = 0;
  u32 vip_idx = 0;

  if (vip->port != 0)
    {
      /* for per-port vip, if VIP adjacency has been added,
       * no need to add adjacency. */
      if (!lb_vip_port_find_diff_port(&(vip->prefix), vip->plen,
                                      vip->protocol, vip->port, &vip_idx))
        {
          lb_vip_t *exists_vip = lb_vip_get_by_index(vip_idx);
          *vip_prefix_index = exists_vip ? exists_vip->vip_prefix_index : ~0;
          return;
        }

      /* Allocate an index for per-port vip */
      *vip_prefix_index = lb_vip_prefix_index_alloc(lbm);
    }
  else
    {
      *vip_prefix_index = vip - lbm->vips;
    }

  dpo_id_t dpo = DPO_INVALID;
  fib_prefix_t pfx = {};
  if (lb_vip_is_ip4(vip->type)) {
      pfx.fp_addr.ip4 = vip->prefix.ip4;
      pfx.fp_len = vip->plen - 96;
      pfx.fp_proto = FIB_PROTOCOL_IP4;
      proto = DPO_PROTO_IP4;
  } else {
      pfx.fp_addr.ip6 = vip->prefix.ip6;
      pfx.fp_len = vip->plen;
      pfx.fp_proto = FIB_PROTOCOL_IP6;
      proto = DPO_PROTO_IP6;
  }

  if (lb_vip_is_gre4(vip))
    dpo_type = lbm->dpo_gre4_type;
  else if (lb_vip_is_gre6(vip))
    dpo_type = lbm->dpo_gre6_type;
  else if (lb_vip_is_gre4_port(vip))
    dpo_type = lbm->dpo_gre4_port_type;
  else if (lb_vip_is_gre6_port(vip))
    dpo_type = lbm->dpo_gre6_port_type;
  else if (lb_vip_is_l3dsr(vip))
    dpo_type = lbm->dpo_l3dsr_type;
  else if (lb_vip_is_l3dsr_port(vip))
    dpo_type = lbm->dpo_l3dsr_port_type;
  else if(lb_vip_is_nat4_port(vip))
    dpo_type = lbm->dpo_nat4_port_type;
  else if (lb_vip_is_nat6_port(vip))
    dpo_type = lbm->dpo_nat6_port_type;

  dpo_set(&dpo, dpo_type, proto, *vip_prefix_index);
  fib_table_entry_special_dpo_add(0,
                                  &pfx,
                                  lb_fib_src,
                                  FIB_ENTRY_FLAG_EXCLUSIVE,
                                  &dpo);
  dpo_reset(&dpo);
}

/**
 * Add the VIP filter entry
 */
static int lb_vip_add_port_filter(lb_main_t *lbm, lb_vip_t *vip,
                                  u32 vip_prefix_index, u32 vip_idx)
{
  vip_port_key_t key;
  clib_bihash_kv_8_8_t kv;

  key.vip_prefix_index = vip_prefix_index;
  key.protocol = vip->protocol;
  key.port = clib_host_to_net_u16(vip->port);
  key.rsv = 0;

  kv.key = key.as_u64;
  kv.value = vip_idx;
  clib_bihash_add_del_8_8(&lbm->vip_index_per_port, &kv, 1);

  return 0;
}

/**
 * Del the VIP filter entry
 */
static int lb_vip_del_port_filter(lb_main_t *lbm, lb_vip_t *vip)
{
  vip_port_key_t key;
  clib_bihash_kv_8_8_t kv, value;
  lb_vip_t *m = 0;

  key.vip_prefix_index = vip->vip_prefix_index;
  key.protocol = vip->protocol;
  key.port = clib_host_to_net_u16(vip->port);
  key.rsv = 0;

  kv.key = key.as_u64;
  if(clib_bihash_search_8_8(&lbm->vip_index_per_port, &kv, &value) != 0)
    {
      clib_warning("looking up vip_index_per_port failed.");
      return VNET_API_ERROR_NO_SUCH_ENTRY;
    }
  m = pool_elt_at_index (lbm->vips, value.value);
  ASSERT (m);

  kv.value = m - lbm->vips;
  clib_bihash_add_del_8_8(&lbm->vip_index_per_port, &kv, 0);

  return 0;
}

/**
 * Deletes the adjacency associated with the VIP
 */
static void lb_vip_del_adjacency(lb_main_t *lbm, lb_vip_t *vip)
{
  fib_prefix_t pfx = {};
  u32 vip_idx = 0;

  if (vip->port != 0)
    {
      /* If this vip adjacency is used by other per-port vip,
       * no need to del this adjacency. */
      if (!lb_vip_port_find_diff_port(&(vip->prefix), vip->plen,
                                      vip->protocol, vip->port, &vip_idx))
        {
          lb_put_writer_lock();
          return;
        }

      /* Return vip_prefix_index for per-port vip */
      lb_vip_prefix_index_free(lbm, vip->vip_prefix_index);

    }

  if (lb_vip_is_ip4(vip->type)) {
      pfx.fp_addr.ip4 = vip->prefix.ip4;
      pfx.fp_len = vip->plen - 96;
      pfx.fp_proto = FIB_PROTOCOL_IP4;
  } else {
      pfx.fp_addr.ip6 = vip->prefix.ip6;
      pfx.fp_len = vip->plen;
      pfx.fp_proto = FIB_PROTOCOL_IP6;
  }
  fib_table_entry_special_remove(0, &pfx, lb_fib_src);
}

int lb_vip_add(lb_vip_add_args_t args, u32 *vip_index)
{
  lb_main_t *lbm = &lb_main;
  vlib_main_t *vm = vlib_get_main();
  lb_vip_t *vip;
  lb_vip_type_t type = args.type;
  u32 vip_prefix_index = 0;

  lb_get_writer_lock();
  ip46_prefix_normalize(&(args.prefix), args.plen);

  if (!lb_vip_port_find_index_with_lock(&(args.prefix), args.plen,
                                         args.protocol, args.port,
                                         vip_index))
    {
      lb_put_writer_lock();
      return VNET_API_ERROR_VALUE_EXIST;
    }

  /* Make sure we can't add a per-port VIP entry
   * when there already is an all-port VIP for the same prefix. */
  if ((args.port != 0) &&
      !lb_vip_port_find_all_port_vip(&(args.prefix), args.plen, vip_index))
    {
      lb_put_writer_lock();
      return VNET_API_ERROR_VALUE_EXIST;
    }

  /* Make sure we can't add a all-port VIP entry
   * when there already is an per-port VIP for the same prefix. */
  if ((args.port == 0) &&
      !lb_vip_port_find_diff_port(&(args.prefix), args.plen,
                                  args.protocol, args.port, vip_index))
    {
      lb_put_writer_lock();
      return VNET_API_ERROR_VALUE_EXIST;
    }

  /* Make sure all VIP for a given prefix (using different ports) have the same type. */
  if ((args.port != 0) &&
      !lb_vip_port_find_diff_port(&(args.prefix), args.plen,
                                  args.protocol, args.port, vip_index)
      && (args.type != lbm->vips[*vip_index].type))
    {
      lb_put_writer_lock();
      return VNET_API_ERROR_INVALID_ARGUMENT;
    }

  if (!is_pow2(args.new_length)) {
    lb_put_writer_lock();
    return VNET_API_ERROR_INVALID_MEMORY_SIZE;
  }

  if (ip46_prefix_is_ip4(&(args.prefix), args.plen) &&
      !lb_vip_is_ip4(type)) {
    lb_put_writer_lock();
    return VNET_API_ERROR_INVALID_ADDRESS_FAMILY;
  }

  if ((!ip46_prefix_is_ip4(&(args.prefix), args.plen)) &&
      !lb_vip_is_ip6(type)) {
    lb_put_writer_lock();
    return VNET_API_ERROR_INVALID_ADDRESS_FAMILY;
  }

  if ((type == LB_VIP_TYPE_IP4_L3DSR) &&
      (args.encap_args.dscp >= 64) )
    {
      lb_put_writer_lock();
      return VNET_API_ERROR_VALUE_EXIST;
    }

  //Allocate
  pool_get(lbm->vips, vip);

  //Init
  memcpy (&(vip->prefix), &(args.prefix), sizeof(args.prefix));
  vip->plen = args.plen;
  if (args.port != 0)
    {
      vip->protocol = args.protocol;
      vip->port = args.port;
    }
  else
    {
      vip->protocol = (u8)~0;
      vip->port = 0;
    }
  vip->last_garbage_collection = (u32) vlib_time_now(vlib_get_main());
  vip->type = args.type;

  if (args.type == LB_VIP_TYPE_IP4_L3DSR) {
      vip->encap_args.dscp = args.encap_args.dscp;
    }
  else if ((args.type == LB_VIP_TYPE_IP4_NAT4)
           ||(args.type == LB_VIP_TYPE_IP6_NAT6)) {
      vip->encap_args.srv_type = args.encap_args.srv_type;
      vip->encap_args.target_port =
          clib_host_to_net_u16(args.encap_args.target_port);
    }

  vip->flags = LB_VIP_FLAGS_USED;
  vip->as_indexes = 0;

  //Validate counters
  u32 i;
  for (i = 0; i < LB_N_VIP_COUNTERS; i++) {
    vlib_validate_simple_counter(&lbm->vip_counters[i], vip - lbm->vips);
    vlib_zero_simple_counter(&lbm->vip_counters[i], vip - lbm->vips);
  }

  //Configure new flow table
  vip->new_flow_table_mask = args.new_length - 1;
  vip->new_flow_table = 0;

  //Update flow hash table
  lb_vip_update_new_flow_table(vip);

  //Create adjacency to direct traffic
  lb_vip_add_adjacency(lbm, vip, &vip_prefix_index);

  if ( (lb_vip_is_nat4_port(vip) || lb_vip_is_nat6_port(vip))
      && (args.encap_args.srv_type == LB_SRV_TYPE_NODEPORT) )
    {
      u32 key;
      uword * entry;

      //Create maping from nodeport to vip_index
      key = clib_host_to_net_u16(args.port);
      entry = hash_get_mem (lbm->vip_index_by_nodeport, &key);
      if (entry) {
        lb_put_writer_lock();
        return VNET_API_ERROR_VALUE_EXIST;
      }

      hash_set_mem (lbm->vip_index_by_nodeport, &key, vip - lbm->vips);

      /* receive packets destined to NodeIP:NodePort */
      udp_register_dst_port (vm, args.port, lb4_nodeport_node.index, 1);
      udp_register_dst_port (vm, args.port, lb6_nodeport_node.index, 0);
    }

  *vip_index = vip - lbm->vips;
  //Create per-port vip filtering table
  if (args.port != 0)
    {
      lb_vip_add_port_filter(lbm, vip, vip_prefix_index, *vip_index);
      vip->vip_prefix_index = vip_prefix_index;
    }

  lb_put_writer_lock();
  return 0;
}

int lb_vip_del(u32 vip_index)
{
  lb_main_t *lbm = &lb_main;
  lb_vip_t *vip;
  int rv = 0;

  /* Does not remove default vip, i.e. vip_index = 0 */
  if (vip_index == 0)
    return VNET_API_ERROR_INVALID_VALUE;

  lb_get_writer_lock();
  if (!(vip = lb_vip_get_by_index(vip_index))) {
    lb_put_writer_lock();
    return VNET_API_ERROR_NO_SUCH_ENTRY;
  }

  //FIXME: This operation is actually not working
  //We will need to remove state before performing this.

  {
    //Remove all ASs
    ip46_address_t *ass = 0;
    lb_as_t *as;
    u32 *as_index;

    pool_foreach(as_index, vip->as_indexes, {
        as = &lbm->ass[*as_index];
        vec_add1(ass, as->address);
    });
    if (vec_len(ass))
      lb_vip_del_ass_withlock(vip_index, ass, vec_len(ass), 0);
    vec_free(ass);
  }

  //Delete adjacency
  lb_vip_del_adjacency(lbm, vip);

  //Delete per-port vip filtering entry
  if (vip->port != 0)
    {
      rv = lb_vip_del_port_filter(lbm, vip);
    }

  //Set the VIP as unused
  vip->flags &= ~LB_VIP_FLAGS_USED;

  lb_put_writer_lock();
  return rv;
}

/* *INDENT-OFF* */
VLIB_PLUGIN_REGISTER () = {
    .version = VPP_BUILD_VER,
    .description = "Load Balancer (LB)",
};
/* *INDENT-ON* */

u8 *format_lb_dpo (u8 * s, va_list * va)
{
  index_t index = va_arg (*va, index_t);
  CLIB_UNUSED(u32 indent) = va_arg (*va, u32);
  lb_main_t *lbm = &lb_main;
  lb_vip_t *vip = pool_elt_at_index (lbm->vips, index);
  return format (s, "%U", format_lb_vip, vip);
}

static void lb_dpo_lock (dpo_id_t *dpo) {}
static void lb_dpo_unlock (dpo_id_t *dpo) {}

static fib_node_t *
lb_fib_node_get_node (fib_node_index_t index)
{
  lb_main_t *lbm = &lb_main;
  lb_as_t *as = pool_elt_at_index (lbm->ass, index);
  return (&as->fib_node);
}

static void
lb_fib_node_last_lock_gone (fib_node_t *node)
{
}

static lb_as_t *
lb_as_from_fib_node (fib_node_t *node)
{
  return ((lb_as_t*)(((char*)node) -
      STRUCT_OFFSET_OF(lb_as_t, fib_node)));
}

static void
lb_as_stack (lb_as_t *as)
{
  lb_main_t *lbm = &lb_main;
  lb_vip_t *vip = &lbm->vips[as->vip_index];
  dpo_type_t dpo_type = 0;

  if (lb_vip_is_gre4(vip))
    dpo_type = lbm->dpo_gre4_type;
  else if (lb_vip_is_gre6(vip))
    dpo_type = lbm->dpo_gre6_type;
  else if (lb_vip_is_gre4_port(vip))
    dpo_type = lbm->dpo_gre4_port_type;
  else if (lb_vip_is_gre6_port(vip))
    dpo_type = lbm->dpo_gre6_port_type;
  else if (lb_vip_is_l3dsr(vip))
    dpo_type = lbm->dpo_l3dsr_type;
  else if (lb_vip_is_l3dsr_port(vip))
    dpo_type = lbm->dpo_l3dsr_port_type;
  else if(lb_vip_is_nat4_port(vip))
    dpo_type = lbm->dpo_nat4_port_type;
  else if (lb_vip_is_nat6_port(vip))
    dpo_type = lbm->dpo_nat6_port_type;

  dpo_stack(dpo_type,
            lb_vip_is_ip4(vip->type)?DPO_PROTO_IP4:DPO_PROTO_IP6,
            &as->dpo,
            fib_entry_contribute_ip_forwarding(
                as->next_hop_fib_entry_index));
}

static fib_node_back_walk_rc_t
lb_fib_node_back_walk_notify (fib_node_t *node,
                 fib_node_back_walk_ctx_t *ctx)
{
    lb_as_stack(lb_as_from_fib_node(node));
    return (FIB_NODE_BACK_WALK_CONTINUE);
}

int lb_nat4_interface_add_del (u32 sw_if_index, int is_del)
{
  if (is_del)
    {
      vnet_feature_enable_disable ("ip4-unicast", "lb-nat4-in2out",
                                   sw_if_index, 0, 0, 0);
    }
  else
    {
      vnet_feature_enable_disable ("ip4-unicast", "lb-nat4-in2out",
                                   sw_if_index, 1, 0, 0);
    }

  return 0;
}

int lb_nat6_interface_add_del (u32 sw_if_index, int is_del)
{
  if (is_del)
    {
      vnet_feature_enable_disable ("ip6-unicast", "lb-nat6-in2out",
                                   sw_if_index, 0, 0, 0);
    }
  else
    {
      vnet_feature_enable_disable ("ip6-unicast", "lb-nat6-in2out",
                                   sw_if_index, 1, 0, 0);
    }

  return 0;
}

clib_error_t *
lb_init (vlib_main_t * vm)
{
  vlib_thread_main_t *tm = vlib_get_thread_main ();
  lb_main_t *lbm = &lb_main;
  lbm->vnet_main = vnet_get_main ();
  lbm->vlib_main = vm;

  lb_vip_t *default_vip;
  lb_as_t *default_as;
  fib_node_vft_t lb_fib_node_vft = {
      .fnv_get = lb_fib_node_get_node,
      .fnv_last_lock = lb_fib_node_last_lock_gone,
      .fnv_back_walk = lb_fib_node_back_walk_notify,
  };
  dpo_vft_t lb_vft = {
      .dv_lock = lb_dpo_lock,
      .dv_unlock = lb_dpo_unlock,
      .dv_format = format_lb_dpo,
  };

  //Allocate and init default VIP.
  lbm->vips = 0;
  pool_get(lbm->vips, default_vip);
  default_vip->new_flow_table_mask = 0;
  default_vip->prefix.ip6.as_u64[0] = 0xffffffffffffffffL;
  default_vip->prefix.ip6.as_u64[1] = 0xffffffffffffffffL;
  default_vip->protocol = ~0;
  default_vip->port = 0;
  default_vip->flags = LB_VIP_FLAGS_USED;

  lbm->per_cpu = 0;
  vec_validate(lbm->per_cpu, tm->n_vlib_mains - 1);
  clib_spinlock_init (&lbm->writer_lock);
  lbm->per_cpu_sticky_buckets = LB_DEFAULT_PER_CPU_STICKY_BUCKETS;
  lbm->flow_timeout = LB_DEFAULT_FLOW_TIMEOUT;
  lbm->ip4_src_address.as_u32 = 0xffffffff;
  lbm->ip6_src_address.as_u64[0] = 0xffffffffffffffffL;
  lbm->ip6_src_address.as_u64[1] = 0xffffffffffffffffL;
  lbm->dpo_gre4_type = dpo_register_new_type(&lb_vft, lb_dpo_gre4_nodes);
  lbm->dpo_gre6_type = dpo_register_new_type(&lb_vft, lb_dpo_gre6_nodes);
  lbm->dpo_gre4_port_type = dpo_register_new_type(&lb_vft,
                                                  lb_dpo_gre4_port_nodes);
  lbm->dpo_gre6_port_type = dpo_register_new_type(&lb_vft,
                                                  lb_dpo_gre6_port_nodes);
  lbm->dpo_l3dsr_type = dpo_register_new_type(&lb_vft,
                                              lb_dpo_l3dsr_nodes);
  lbm->dpo_l3dsr_port_type = dpo_register_new_type(&lb_vft,
                                                   lb_dpo_l3dsr_port_nodes);
  lbm->dpo_nat4_port_type = dpo_register_new_type(&lb_vft,
                                                  lb_dpo_nat4_port_nodes);
  lbm->dpo_nat6_port_type = dpo_register_new_type(&lb_vft,
                                                  lb_dpo_nat6_port_nodes);
  lbm->fib_node_type = fib_node_register_new_type(&lb_fib_node_vft);

  //Init AS reference counters
  vlib_refcount_init(&lbm->as_refcount);

  //Allocate and init default AS.
  lbm->ass = 0;
  pool_get(lbm->ass, default_as);
  default_as->flags = 0;
  default_as->dpo.dpoi_next_node = LB_NEXT_DROP;
  default_as->vip_index = ~0;
  default_as->address.ip6.as_u64[0] = 0xffffffffffffffffL;
  default_as->address.ip6.as_u64[1] = 0xffffffffffffffffL;

  /* Generate a valid flow table for default VIP */
  default_vip->as_indexes = NULL;
  lb_get_writer_lock();
  lb_vip_update_new_flow_table(default_vip);
  lb_put_writer_lock();

  lbm->vip_index_by_nodeport
    = hash_create_mem (0, sizeof(u16), sizeof (uword));

  clib_bihash_init_8_8 (&lbm->vip_index_per_port,
                        "vip_index_per_port", LB_VIP_PER_PORT_BUCKETS,
                        LB_VIP_PER_PORT_MEMORY_SIZE);

  clib_bihash_init_8_8 (&lbm->mapping_by_as4,
                        "mapping_by_as4", LB_MAPPING_BUCKETS,
                        LB_MAPPING_MEMORY_SIZE);

  clib_bihash_init_24_8 (&lbm->mapping_by_as6,
                        "mapping_by_as6", LB_MAPPING_BUCKETS,
                        LB_MAPPING_MEMORY_SIZE);

#define _(a,b,c) lbm->vip_counters[c].name = b;
  lb_foreach_vip_counter
#undef _

  lb_fib_src = fib_source_allocate("lb",
                                   FIB_SOURCE_PRIORITY_HI,
                                   FIB_SOURCE_BH_SIMPLE);

  return NULL;
}

VLIB_INIT_FUNCTION (lb_init);