text: /*
   * Copyright (c) 2017-2019 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 Session and session manager
   */
  
  #include <vnet/session/session.h>
  #include <vnet/session/session_debug.h>
  #include <vnet/session/application.h>
  #include <vnet/dpo/load_balance.h>
  #include <vnet/fib/ip4_fib.h>
  
  session_main_t session_main;
  
  static inline int
  session_send_evt_to_thread (void *data, void *args, u32 thread_index,
  			    session_evt_type_t evt_type)
  {
    session_event_t *evt;
    svm_msg_q_msg_t msg;
    svm_msg_q_t *mq;
    u32 tries = 0, max_tries;
  
    mq = session_main_get_vpp_event_queue (thread_index);
    while (svm_msg_q_try_lock (mq))
      {
        max_tries = vlib_get_current_process (vlib_get_main ())? 1e6 : 3;
        if (tries++ == max_tries)
  	{
  	  SESSION_DBG ("failed to enqueue evt");
  	  return -1;
  	}
      }
    if (PREDICT_FALSE (svm_msg_q_ring_is_full (mq, SESSION_MQ_IO_EVT_RING)))
      {
        svm_msg_q_unlock (mq);
        return -2;
      }
    msg = svm_msg_q_alloc_msg_w_ring (mq, SESSION_MQ_IO_EVT_RING);
    if (PREDICT_FALSE (svm_msg_q_msg_is_invalid (&msg)))
      {
        svm_msg_q_unlock (mq);
        return -2;
      }
    evt = (session_event_t *) svm_msg_q_msg_data (mq, &msg);
    evt->event_type = evt_type;
    switch (evt_type)
      {
      case SESSION_CTRL_EVT_RPC:
        evt->rpc_args.fp = data;
        evt->rpc_args.arg = args;
        break;
      case SESSION_IO_EVT_TX:
      case SESSION_IO_EVT_TX_FLUSH:
      case SESSION_IO_EVT_BUILTIN_RX:
        evt->session_index = *(u32 *) data;
        break;
      case SESSION_IO_EVT_BUILTIN_TX:
      case SESSION_CTRL_EVT_CLOSE:
        evt->session_handle = session_handle ((session_t *) data);
        break;
      default:
        clib_warning ("evt unhandled!");
        svm_msg_q_unlock (mq);
        return -1;
      }
  
    svm_msg_q_add_and_unlock (mq, &msg);
    return 0;
  }
  
  int
  session_send_io_evt_to_thread (svm_fifo_t * f, session_evt_type_t evt_type)
  {
    return session_send_evt_to_thread (&f->master_session_index, 0,
  				     f->master_thread_index, evt_type);
  }
  
  int
  session_send_io_evt_to_thread_custom (void *data, u32 thread_index,
  				      session_evt_type_t evt_type)
  {
    return session_send_evt_to_thread (data, 0, thread_index, evt_type);
  }
  
  int
  session_send_ctrl_evt_to_thread (session_t * s, session_evt_type_t evt_type)
  {
    /* only event supported for now is disconnect */
    ASSERT (evt_type == SESSION_CTRL_EVT_CLOSE);
    return session_send_evt_to_thread (s, 0, s->thread_index,
  				     SESSION_CTRL_EVT_CLOSE);
  }
  
  void
  session_send_rpc_evt_to_thread (u32 thread_index, void *fp, void *rpc_args)
  {
    if (thread_index != vlib_get_thread_index ())
      session_send_evt_to_thread (fp, rpc_args, thread_index,
  				SESSION_CTRL_EVT_RPC);
    else
      {
        void (*fnp) (void *) = fp;
        fnp (rpc_args);
      }
  }
  
  static void
  session_program_transport_close (session_t * s)
  {
    u32 thread_index = vlib_get_thread_index ();
    session_worker_t *wrk;
    session_event_t *evt;
  
    /* If we are in the handler thread, or being called with the worker barrier
     * held, just append a new event to pending disconnects vector. */
    if (vlib_thread_is_main_w_barrier () || thread_index == s->thread_index)
      {
        wrk = session_main_get_worker (s->thread_index);
        vec_add2 (wrk->pending_disconnects, evt, 1);
        clib_memset (evt, 0, sizeof (*evt));
        evt->session_handle = session_handle (s);
        evt->event_type = SESSION_CTRL_EVT_CLOSE;
      }
    else
      session_send_ctrl_evt_to_thread (s, SESSION_CTRL_EVT_CLOSE);
  }
  
  session_t *
  session_alloc (u32 thread_index)
  {
    session_worker_t *wrk = &session_main.wrk[thread_index];
    session_t *s;
    u8 will_expand = 0;
    pool_get_aligned_will_expand (wrk->sessions, will_expand,
  				CLIB_CACHE_LINE_BYTES);
    /* If we have peekers, let them finish */
    if (PREDICT_FALSE (will_expand && vlib_num_workers ()))
      {
        clib_rwlock_writer_lock (&wrk->peekers_rw_locks);
        pool_get_aligned (wrk->sessions, s, CLIB_CACHE_LINE_BYTES);
        clib_rwlock_writer_unlock (&wrk->peekers_rw_locks);
      }
    else
      {
        pool_get_aligned (wrk->sessions, s, CLIB_CACHE_LINE_BYTES);
      }
    clib_memset (s, 0, sizeof (*s));
    s->session_index = s - wrk->sessions;
    s->thread_index = thread_index;
    return s;
  }
  
  void
  session_free (session_t * s)
  {
    pool_put (session_main.wrk[s->thread_index].sessions, s);
    if (CLIB_DEBUG)
      clib_memset (s, 0xFA, sizeof (*s));
  }
  
  void
  session_free_w_fifos (session_t * s)
  {
    segment_manager_dealloc_fifos (s->rx_fifo, s->tx_fifo);
    session_free (s);
  }
  
  /**
   * Cleans up session and lookup table.
   *
   * Transport connection must still be valid.
   */
  static void
  session_delete (session_t * s)
  {
    int rv;
  
    /* Delete from the main lookup table. */
    if ((rv = session_lookup_del_session (s)))
      clib_warning ("hash delete error, rv %d", rv);
  
    session_free_w_fifos (s);
  }
  
  static session_t *
  session_alloc_for_connection (transport_connection_t * tc)
  {
    session_t *s;
    u32 thread_index = tc->thread_index;
  
    ASSERT (thread_index == vlib_get_thread_index ()
  	  || transport_protocol_is_cl (tc->proto));
  
    s = session_alloc (thread_index);
    s->session_type = session_type_from_proto_and_ip (tc->proto, tc->is_ip4);
    s->session_state = SESSION_STATE_CLOSED;
  
    /* Attach transport to session and vice versa */
    s->connection_index = tc->c_index;
    tc->s_index = s->session_index;
    return s;
  }
  
  /**
   * Discards bytes from buffer chain
   *
   * It discards n_bytes_to_drop starting at first buffer after chain_b
   */
  always_inline void
  session_enqueue_discard_chain_bytes (vlib_main_t * vm, vlib_buffer_t * b,
  				     vlib_buffer_t ** chain_b,
  				     u32 n_bytes_to_drop)
  {
    vlib_buffer_t *next = *chain_b;
    u32 to_drop = n_bytes_to_drop;
    ASSERT (b->flags & VLIB_BUFFER_NEXT_PRESENT);
    while (to_drop && (next->flags & VLIB_BUFFER_NEXT_PRESENT))
      {
        next = vlib_get_buffer (vm, next->next_buffer);
        if (next->current_length > to_drop)
  	{
  	  vlib_buffer_advance (next, to_drop);
  	  to_drop = 0;
  	}
        else
  	{
  	  to_drop -= next->current_length;
  	  next->current_length = 0;
  	}
      }
    *chain_b = next;
  
    if (to_drop == 0)
      b->total_length_not_including_first_buffer -= n_bytes_to_drop;
  }
  
  /**
   * Enqueue buffer chain tail
   */
  always_inline int
  session_enqueue_chain_tail (session_t * s, vlib_buffer_t * b,
  			    u32 offset, u8 is_in_order)
  {
    vlib_buffer_t *chain_b;
    u32 chain_bi, len, diff;
    vlib_main_t *vm = vlib_get_main ();
    u8 *data;
    u32 written = 0;
    int rv = 0;
  
    if (is_in_order && offset)
      {
        diff = offset - b->current_length;
        if (diff > b->total_length_not_including_first_buffer)
  	return 0;
        chain_b = b;
        session_enqueue_discard_chain_bytes (vm, b, &chain_b, diff);
        chain_bi = vlib_get_buffer_index (vm, chain_b);
      }
    else
      chain_bi = b->next_buffer;
  
    do
      {
        chain_b = vlib_get_buffer (vm, chain_bi);
        data = vlib_buffer_get_current (chain_b);
        len = chain_b->current_length;
        if (!len)
  	continue;
        if (is_in_order)
  	{
  	  rv = svm_fifo_enqueue_nowait (s->rx_fifo, len, data);
  	  if (rv == len)
  	    {
  	      written += rv;
  	    }
  	  else if (rv < len)
  	    {
  	      return (rv > 0) ? (written + rv) : written;
  	    }
  	  else if (rv > len)
  	    {
  	      written += rv;
  
  	      /* written more than what was left in chain */
  	      if (written > b->total_length_not_including_first_buffer)
  		return written;
  
  	      /* drop the bytes that have already been delivered */
  	      session_enqueue_discard_chain_bytes (vm, b, &chain_b, rv - len);
  	    }
  	}
        else
  	{
  	  rv = svm_fifo_enqueue_with_offset (s->rx_fifo, offset, len, data);
  	  if (rv)
  	    {
  	      clib_warning ("failed to enqueue multi-buffer seg");
  	      return -1;
  	    }
  	  offset += len;
  	}
      }
    while ((chain_bi = (chain_b->flags & VLIB_BUFFER_NEXT_PRESENT)
  	  ? chain_b->next_buffer : 0));
  
    if (is_in_order)
      return written;
  
    return 0;
  }
  
  /*
   * Enqueue data for delivery to session peer. Does not notify peer of enqueue
   * event but on request can queue notification events for later delivery by
   * calling stream_server_flush_enqueue_events().
   *
   * @param tc Transport connection which is to be enqueued data
   * @param b Buffer to be enqueued
   * @param offset Offset at which to start enqueueing if out-of-order
   * @param queue_event Flag to indicate if peer is to be notified or if event
   *                    is to be queued. The former is useful when more data is
   *                    enqueued and only one event is to be generated.
   * @param is_in_order Flag to indicate if data is in order
   * @return Number of bytes enqueued or a negative value if enqueueing failed.
   */
  int
  session_enqueue_stream_connection (transport_connection_t * tc,
  				   vlib_buffer_t * b, u32 offset,
  				   u8 queue_event, u8 is_in_order)
  {
    session_t *s;
    int enqueued = 0, rv, in_order_off;
  
    s = session_get (tc->s_index, tc->thread_index);
  
    if (is_in_order)
      {
        enqueued = svm_fifo_enqueue_nowait (s->rx_fifo,
  					  b->current_length,
  					  vlib_buffer_get_current (b));
        if (PREDICT_FALSE ((b->flags & VLIB_BUFFER_NEXT_PRESENT)
  			 && enqueued >= 0))
  	{
  	  in_order_off = enqueued > b->current_length ? enqueued : 0;
  	  rv = session_enqueue_chain_tail (s, b, in_order_off, 1);
  	  if (rv > 0)
  	    enqueued += rv;
  	}
      }
    else
      {
        rv = svm_fifo_enqueue_with_offset (s->rx_fifo, offset,
  					 b->current_length,
  					 vlib_buffer_get_current (b));
        if (PREDICT_FALSE ((b->flags & VLIB_BUFFER_NEXT_PRESENT) && !rv))
  	session_enqueue_chain_tail (s, b, offset + b->current_length, 0);
        /* if something was enqueued, report even this as success for ooo
         * segment handling */
        return rv;
      }
  
    if (queue_event)
      {
        /* Queue RX event on this fifo. Eventually these will need to be flushed
         * by calling stream_server_flush_enqueue_events () */
        session_worker_t *wrk;
  
        wrk = session_main_get_worker (s->thread_index);
        if (!(s->flags & SESSION_F_RX_EVT))
  	{
  	  s->flags |= SESSION_F_RX_EVT;
  	  vec_add1 (wrk->session_to_enqueue[tc->proto], s->session_index);
  	}
      }
  
    return enqueued;
  }
  
  int
  session_enqueue_dgram_connection (session_t * s,
  				  session_dgram_hdr_t * hdr,
  				  vlib_buffer_t * b, u8 proto, u8 queue_event)
  {
    int enqueued = 0, rv, in_order_off;
  
    ASSERT (svm_fifo_max_enqueue (s->rx_fifo)
  	  >= b->current_length + sizeof (*hdr));
  
    svm_fifo_enqueue_nowait (s->rx_fifo, sizeof (session_dgram_hdr_t),
  			   (u8 *) hdr);
    enqueued = svm_fifo_enqueue_nowait (s->rx_fifo, b->current_length,
  				      vlib_buffer_get_current (b));
    if (PREDICT_FALSE ((b->flags & VLIB_BUFFER_NEXT_PRESENT) && enqueued >= 0))
      {
        in_order_off = enqueued > b->current_length ? enqueued : 0;
        rv = session_enqueue_chain_tail (s, b, in_order_off, 1);
        if (rv > 0)
  	enqueued += rv;
      }
    if (queue_event)
      {
        /* Queue RX event on this fifo. Eventually these will need to be flushed
         * by calling stream_server_flush_enqueue_events () */
        session_worker_t *wrk;
  
        wrk = session_main_get_worker (s->thread_index);
        if (!(s->flags & SESSION_F_RX_EVT))
  	{
  	  s->flags |= SESSION_F_RX_EVT;
  	  vec_add1 (wrk->session_to_enqueue[proto], s->session_index);
  	}
      }
    return enqueued;
  }
  
  int
  session_tx_fifo_peek_bytes (transport_connection_t * tc, u8 * buffer,
  			    u32 offset, u32 max_bytes)
  {
    session_t *s = session_get (tc->s_index, tc->thread_index);
    return svm_fifo_peek (s->tx_fifo, offset, max_bytes, buffer);
  }
  
  u32
  session_tx_fifo_dequeue_drop (transport_connection_t * tc, u32 max_bytes)
  {
    session_t *s = session_get (tc->s_index, tc->thread_index);
    return svm_fifo_dequeue_drop (s->tx_fifo, max_bytes);
  }
  
  static inline int
  session_notify_subscribers (u32 app_index, session_t * s,
  			    svm_fifo_t * f, session_evt_type_t evt_type)
  {
    app_worker_t *app_wrk;
    application_t *app;
    int i;
  
    app = application_get (app_index);
    if (!app)
      return -1;
  
    for (i = 0; i < f->n_subscribers; i++)
      {
        app_wrk = application_get_worker (app, f->subscribers[i]);
        if (!app_wrk)
  	continue;
        if (app_worker_lock_and_send_event (app_wrk, s, evt_type))
  	return -1;
      }
  
    return 0;
  }
  
  /**
   * Notify session peer that new data has been enqueued.
   *
   * @param s 	Stream session for which the event is to be generated.
   * @param lock 	Flag to indicate if call should lock message queue.
   *
   * @return 0 on success or negative number if failed to send notification.
   */
  static inline int
  session_enqueue_notify_inline (session_t * s)
  {
    app_worker_t *app_wrk;
  
    app_wrk = app_worker_get_if_valid (s->app_wrk_index);
    if (PREDICT_FALSE (!app_wrk))
      {
        SESSION_DBG ("invalid s->app_index = %d", s->app_wrk_index);
        return 0;
      }
  
    /* *INDENT-OFF* */
    SESSION_EVT_DBG(SESSION_EVT_ENQ, s, ({
        ed->data[0] = SESSION_IO_EVT_RX;
        ed->data[1] = svm_fifo_max_dequeue (s->rx_fifo);
    }));
    /* *INDENT-ON* */
  
    s->flags &= ~SESSION_F_RX_EVT;
    if (PREDICT_FALSE (app_worker_lock_and_send_event (app_wrk, s,
  						     SESSION_IO_EVT_RX)))
      return -1;
  
    if (PREDICT_FALSE (svm_fifo_n_subscribers (s->rx_fifo)))
      return session_notify_subscribers (app_wrk->app_index, s,
  				       s->rx_fifo, SESSION_IO_EVT_RX);
  
    return 0;
  }
  
  int
  session_enqueue_notify (session_t * s)
  {
    return session_enqueue_notify_inline (s);
  }
  
  int
  session_dequeue_notify (session_t * s)
  {
    app_worker_t *app_wrk;
  
    app_wrk = app_worker_get_if_valid (s->app_wrk_index);
    if (PREDICT_FALSE (!app_wrk))
      return -1;
  
    if (PREDICT_FALSE (app_worker_lock_and_send_event (app_wrk, s,
  						     SESSION_IO_EVT_TX)))
      return -1;
  
    if (PREDICT_FALSE (s->tx_fifo->n_subscribers))
      return session_notify_subscribers (app_wrk->app_index, s,
  				       s->tx_fifo, SESSION_IO_EVT_TX);
  
    svm_fifo_clear_tx_ntf (s->tx_fifo);
  
    return 0;
  }
  
  /**
   * Flushes queue of sessions that are to be notified of new data
   * enqueued events.
   *
   * @param thread_index Thread index for which the flush is to be performed.
   * @return 0 on success or a positive number indicating the number of
   *         failures due to API queue being full.
   */
  int
  session_main_flush_enqueue_events (u8 transport_proto, u32 thread_index)
  {
    session_worker_t *wrk = session_main_get_worker (thread_index);
    session_t *s;
    int i, errors = 0;
    u32 *indices;
  
    indices = wrk->session_to_enqueue[transport_proto];
  
    for (i = 0; i < vec_len (indices); i++)
      {
        s = session_get_if_valid (indices[i], thread_index);
        if (PREDICT_FALSE (!s))
  	{
  	  errors++;
  	  continue;
  	}
  
        if (svm_fifo_has_event (s->rx_fifo) || svm_fifo_is_empty (s->rx_fifo))
  	continue;
  
        if (PREDICT_FALSE (session_enqueue_notify_inline (s)))
  	errors++;
      }
  
    vec_reset_length (indices);
    wrk->session_to_enqueue[transport_proto] = indices;
  
    return errors;
  }
  
  int
  session_main_flush_all_enqueue_events (u8 transport_proto)
  {
    vlib_thread_main_t *vtm = vlib_get_thread_main ();
    int i, errors = 0;
    for (i = 0; i < 1 + vtm->n_threads; i++)
      errors += session_main_flush_enqueue_events (transport_proto, i);
    return errors;
  }
  
  int
  session_stream_connect_notify (transport_connection_t * tc, u8 is_fail)
  {
    u32 opaque = 0, new_ti, new_si;
    app_worker_t *app_wrk;
    session_t *s = 0;
    u64 ho_handle;
  
    /*
     * Find connection handle and cleanup half-open table
     */
    ho_handle = session_lookup_half_open_handle (tc);
    if (ho_handle == HALF_OPEN_LOOKUP_INVALID_VALUE)
      {
        SESSION_DBG ("half-open was removed!");
        return -1;
      }
    session_lookup_del_half_open (tc);
  
    /* Get the app's index from the handle we stored when opening connection
     * and the opaque (api_context for external apps) from transport session
     * index */
    app_wrk = app_worker_get_if_valid (ho_handle >> 32);
    if (!app_wrk)
      return -1;
  
    opaque = tc->s_index;
  
    if (is_fail)
      return app_worker_connect_notify (app_wrk, s, opaque);
  
    s = session_alloc_for_connection (tc);
    s->session_state = SESSION_STATE_CONNECTING;
    s->app_wrk_index = app_wrk->wrk_index;
    new_si = s->session_index;
    new_ti = s->thread_index;
  
    if (app_worker_init_connected (app_wrk, s))
      {
        session_free (s);
        app_worker_connect_notify (app_wrk, 0, opaque);
        return -1;
      }
  
    if (app_worker_connect_notify (app_wrk, s, opaque))
      {
        s = session_get (new_si, new_ti);
        session_free_w_fifos (s);
        return -1;
      }
  
    s = session_get (new_si, new_ti);
    s->session_state = SESSION_STATE_READY;
    session_lookup_add_connection (tc, session_handle (s));
  
    return 0;
  }
  
  typedef struct _session_switch_pool_args
  {
    u32 session_index;
    u32 thread_index;
    u32 new_thread_index;
    u32 new_session_index;
  } session_switch_pool_args_t;
  
  static void
  session_switch_pool (void *cb_args)
  {
    session_switch_pool_args_t *args = (session_switch_pool_args_t *) cb_args;
    session_t *s;
    ASSERT (args->thread_index == vlib_get_thread_index ());
    s = session_get (args->session_index, args->thread_index);
    s->tx_fifo->master_session_index = args->new_session_index;
    s->tx_fifo->master_thread_index = args->new_thread_index;
    transport_cleanup (session_get_transport_proto (s), s->connection_index,
  		     s->thread_index);
    session_free (s);
    clib_mem_free (cb_args);
  }
  
  /**
   * Move dgram session to the right thread
   */
  int
  session_dgram_connect_notify (transport_connection_t * tc,
  			      u32 old_thread_index, session_t ** new_session)
  {
    session_t *new_s;
    session_switch_pool_args_t *rpc_args;
  
    /*
     * Clone half-open session to the right thread.
     */
    new_s = session_clone_safe (tc->s_index, old_thread_index);
    new_s->connection_index = tc->c_index;
    new_s->rx_fifo->master_session_index = new_s->session_index;
    new_s->rx_fifo->master_thread_index = new_s->thread_index;
    new_s->session_state = SESSION_STATE_READY;
    session_lookup_add_connection (tc, session_handle (new_s));
  
    /*
     * Ask thread owning the old session to clean it up and make us the tx
     * fifo owner
     */
    rpc_args = clib_mem_alloc (sizeof (*rpc_args));
    rpc_args->new_session_index = new_s->session_index;
    rpc_args->new_thread_index = new_s->thread_index;
    rpc_args->session_index = tc->s_index;
    rpc_args->thread_index = old_thread_index;
    session_send_rpc_evt_to_thread (rpc_args->thread_index, session_switch_pool,
  				  rpc_args);
  
    tc->s_index = new_s->session_index;
    new_s->connection_index = tc->c_index;
    *new_session = new_s;
    return 0;
  }
  
  /**
   * Notification from transport that connection is being closed.
   *
   * A disconnect is sent to application but state is not removed. Once
   * disconnect is acknowledged by application, session disconnect is called.
   * Ultimately this leads to close being called on transport (passive close).
   */
  void
  session_transport_closing_notify (transport_connection_t * tc)
  {
    app_worker_t *app_wrk;
    session_t *s;
  
    s = session_get (tc->s_index, tc->thread_index);
    if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSING)
      return;
    s->session_state = SESSION_STATE_TRANSPORT_CLOSING;
    app_wrk = app_worker_get (s->app_wrk_index);
    app_worker_close_notify (app_wrk, s);
  }
  
  /**
   * Notification from transport that connection is being deleted
   *
   * This removes the session if it is still valid. It should be called only on
   * previously fully established sessions. For instance failed connects should
   * call stream_session_connect_notify and indicate that the connect has
   * failed.
   */
  void
  session_transport_delete_notify (transport_connection_t * tc)
  {
    session_t *s;
  
    /* App might've been removed already */
    if (!(s = session_get_if_valid (tc->s_index, tc->thread_index)))
      return;
  
    /* Make sure we don't try to send anything more */
    svm_fifo_dequeue_drop_all (s->tx_fifo);
  
    switch (s->session_state)
      {
      case SESSION_STATE_CREATED:
        /* Session was created but accept notification was not yet sent to the
         * app. Cleanup everything. */
        session_lookup_del_session (s);
        session_free_w_fifos (s);
        break;
      case SESSION_STATE_ACCEPTING:
      case SESSION_STATE_TRANSPORT_CLOSING:
        /* If transport finishes or times out before we get a reply
         * from the app, mark transport as closed and wait for reply
         * before removing the session. Cleanup session table in advance
         * because transport will soon be closed and closed sessions
         * are assumed to have been removed from the lookup table */
        session_lookup_del_session (s);
        s->session_state = SESSION_STATE_TRANSPORT_CLOSED;
        break;
      case SESSION_STATE_CLOSING:
      case SESSION_STATE_CLOSED_WAITING:
        /* Cleanup lookup table as transport needs to still be valid.
         * Program transport close to ensure that all session events
         * have been cleaned up. Once transport close is called, the
         * session is just removed because both transport and app have
         * confirmed the close*/
        session_lookup_del_session (s);
        s->session_state = SESSION_STATE_TRANSPORT_CLOSED;
        session_program_transport_close (s);
        break;
      case SESSION_STATE_TRANSPORT_CLOSED:
        break;
      case SESSION_STATE_CLOSED:
        session_delete (s);
        break;
      default:
        clib_warning ("session state %u", s->session_state);
        session_delete (s);
        break;
      }
  }
  
  /**
   * Notification from transport that session can be closed
   *
   * Should be called by transport only if it was closed with non-empty
   * tx fifo and once it decides to begin the closing procedure prior to
   * issuing a delete notify. This gives the chance to the session layer
   * to cleanup any outstanding events.
   */
  void
  session_transport_closed_notify (transport_connection_t * tc)
  {
    session_t *s;
  
    if (!(s = session_get_if_valid (tc->s_index, tc->thread_index)))
      return;
  
    /* If app close has not been received or has not yet resulted in
     * a transport close, only mark the session transport as closed */
    if (s->session_state <= SESSION_STATE_CLOSING)
      {
        session_lookup_del_session (s);
        s->session_state = SESSION_STATE_TRANSPORT_CLOSED;
      }
    else
      s->session_state = SESSION_STATE_CLOSED;
  }
  
  /**
   * Notify application that connection has been reset.
   */
  void
  session_transport_reset_notify (transport_connection_t * tc)
  {
    session_t *s;
    app_worker_t *app_wrk;
    application_t *app;
    s = session_get (tc->s_index, tc->thread_index);
    svm_fifo_dequeue_drop_all (s->tx_fifo);
    if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSING)
      return;
    s->session_state = SESSION_STATE_TRANSPORT_CLOSING;
    app_wrk = app_worker_get (s->app_wrk_index);
    app = application_get (app_wrk->app_index);
    app->cb_fns.session_reset_callback (s);
  }
  
  int
  session_stream_accept_notify (transport_connection_t * tc)
  {
    app_worker_t *app_wrk;
    session_t *s;
  
    s = session_get (tc->s_index, tc->thread_index);
    app_wrk = app_worker_get_if_valid (s->app_wrk_index);
    if (!app_wrk)
      return -1;
    s->session_state = SESSION_STATE_ACCEPTING;
    return app_worker_accept_notify (app_wrk, s);
  }
  
  /**
   * Accept a stream session. Optionally ping the server by callback.
   */
  int
  session_stream_accept (transport_connection_t * tc, u32 listener_index,
  		       u8 notify)
  {
    session_t *s;
    int rv;
  
    s = session_alloc_for_connection (tc);
    s->listener_index = listener_index;
    s->session_state = SESSION_STATE_CREATED;
  
    if ((rv = app_worker_init_accepted (s)))
      return rv;
  
    session_lookup_add_connection (tc, session_handle (s));
  
    /* Shoulder-tap the server */
    if (notify)
      {
        app_worker_t *app_wrk = app_worker_get (s->app_wrk_index);
        return app_worker_accept_notify (app_wrk, s);
      }
  
    return 0;
  }
  
  int
  session_open_cl (u32 app_wrk_index, session_endpoint_t * rmt, u32 opaque)
  {
    transport_connection_t *tc;
    transport_endpoint_cfg_t *tep;
    app_worker_t *app_wrk;
    session_t *s;
    int rv;
  
    tep = session_endpoint_to_transport_cfg (rmt);
    rv = transport_connect (rmt->transport_proto, tep);
    if (rv < 0)
      {
        SESSION_DBG ("Transport failed to open connection.");
        return VNET_API_ERROR_SESSION_CONNECT;
      }
  
    tc = transport_get_half_open (rmt->transport_proto, (u32) rv);
  
    /* For dgram type of service, allocate session and fifos now */
    app_wrk = app_worker_get (app_wrk_index);
    s = session_alloc_for_connection (tc);
    s->app_wrk_index = app_wrk->wrk_index;
    s->session_state = SESSION_STATE_OPENED;
    if (app_worker_init_connected (app_wrk, s))
      {
        session_free (s);
        return -1;
      }
  
    return app_worker_connect_notify (app_wrk, s, opaque);
  }
  
  int
  session_open_vc (u32 app_wrk_index, session_endpoint_t * rmt, u32 opaque)
  {
    transport_connection_t *tc;
    transport_endpoint_cfg_t *tep;
    u64 handle;
    int rv;
  
    tep = session_endpoint_to_transport_cfg (rmt);
    rv = transport_connect (rmt->transport_proto, tep);
    if (rv < 0)
      {
        SESSION_DBG ("Transport failed to open connection.");
        return VNET_API_ERROR_SESSION_CONNECT;
      }
  
    tc = transport_get_half_open (rmt->transport_proto, (u32) rv);
  
    /* If transport offers a stream service, only allocate session once the
     * connection has been established.
     * Add connection to half-open table and save app and tc index. The
     * latter is needed to help establish the connection while the former
     * is needed when the connect notify comes and we have to notify the
     * external app
     */
    handle = (((u64) app_wrk_index) << 32) | (u64) tc->c_index;
    session_lookup_add_half_open (tc, handle);
  
    /* Store api_context (opaque) for when the reply comes. Not the nicest
     * thing but better than allocating a separate half-open pool.
     */
    tc->s_index = opaque;
    return 0;
  }
  
  int
  session_open_app (u32 app_wrk_index, session_endpoint_t * rmt, u32 opaque)
  {
    session_endpoint_cfg_t *sep = (session_endpoint_cfg_t *) rmt;
    transport_endpoint_cfg_t *tep_cfg = session_endpoint_to_transport_cfg (sep);
  
    sep->app_wrk_index = app_wrk_index;
    sep->opaque = opaque;
  
    return transport_connect (rmt->transport_proto, tep_cfg);
  }
  
  typedef int (*session_open_service_fn) (u32, session_endpoint_t *, u32);
  
  /* *INDENT-OFF* */
  static session_open_service_fn session_open_srv_fns[TRANSPORT_N_SERVICES] = {
    session_open_vc,
    session_open_cl,
    session_open_app,
  };
  /* *INDENT-ON* */
  
  /**
   * Ask transport to open connection to remote transport endpoint.
   *
   * Stores handle for matching request with reply since the call can be
   * asynchronous. For instance, for TCP the 3-way handshake must complete
   * before reply comes. Session is only created once connection is established.
   *
   * @param app_index Index of the application requesting the connect
   * @param st Session type requested.
   * @param tep Remote transport endpoint
   * @param opaque Opaque data (typically, api_context) the application expects
   * 		 on open completion.
   */
  int
  session_open (u32 app_wrk_index, session_endpoint_t * rmt, u32 opaque)
  {
    transport_service_type_t tst;
    tst = transport_protocol_service_type (rmt->transport_proto);
    return session_open_srv_fns[tst] (app_wrk_index, rmt, opaque);
  }
  
  /**
   * Ask transport to listen on session endpoint.
   *
   * @param s Session for which listen will be called. Note that unlike
   * 	    established sessions, listen sessions are not associated to a
   * 	    thread.
   * @param sep Local endpoint to be listened on.
   */
  int
  session_listen (session_t * ls, session_endpoint_cfg_t * sep)
  {
    transport_endpoint_t *tep;
    u32 tc_index, s_index;
  
    /* Transport bind/listen */
    tep = session_endpoint_to_transport (sep);
    s_index = ls->session_index;
    tc_index = transport_start_listen (session_get_transport_proto (ls),
  				     s_index, tep);
  
    if (tc_index == (u32) ~ 0)
      return -1;
  
    /* Attach transport to session. Lookup tables are populated by the app
     * worker because local tables (for ct sessions) are not backed by a fib */
    ls = listen_session_get (s_index);
    ls->connection_index = tc_index;
  
    return 0;
  }
  
  /**
   * Ask transport to stop listening on local transport endpoint.
   *
   * @param s Session to stop listening on. It must be in state LISTENING.
   */
  int
  session_stop_listen (session_t * s)
  {
    transport_proto_t tp = session_get_transport_proto (s);
    transport_connection_t *tc;
  
    if (s->session_state != SESSION_STATE_LISTENING)
      return -1;
  
    tc = transport_get_listener (tp, s->connection_index);
    if (!tc)
      return VNET_API_ERROR_ADDRESS_NOT_IN_USE;
  
    session_lookup_del_connection (tc);
    transport_stop_listen (tp, s->connection_index);
    return 0;
  }
  
  /**
   * Initialize session closing procedure.
   *
   * Request is always sent to session node to ensure that all outstanding
   * requests are served before transport is notified.
   */
  void
  session_close (session_t * s)
  {
    if (!s)
      return;
  
    if (s->session_state >= SESSION_STATE_CLOSING)
      {
        /* Session will only be removed once both app and transport
         * acknowledge the close */
        if (s->session_state == SESSION_STATE_TRANSPORT_CLOSED)
  	session_program_transport_close (s);
  
        /* Session already closed. Clear the tx fifo */
        if (s->session_state == SESSION_STATE_CLOSED)
  	svm_fifo_dequeue_drop_all (s->tx_fifo);
        return;
      }
  
    s->session_state = SESSION_STATE_CLOSING;
    session_program_transport_close (s);
  }
  
  /**
   * Notify transport the session can be disconnected. This should eventually
   * result in a delete notification that allows us to cleanup session state.
   * Called for both active/passive disconnects.
   *
   * Must be called from the session's thread.
   */
  void
  session_transport_close (session_t * s)
  {
    /* If transport is already closed, just free the session */
    if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED)
      {
        session_free_w_fifos (s);
        return;
      }
  
    /* If tx queue wasn't drained, change state to closed waiting for transport.
     * This way, the transport, if it so wishes, can continue to try sending the
     * outstanding data (in closed state it cannot). It MUST however at one
     * point, either after sending everything or after a timeout, call delete
     * notify. This will finally lead to the complete cleanup of the session.
     */
    if (svm_fifo_max_dequeue (s->tx_fifo))
      s->session_state = SESSION_STATE_CLOSED_WAITING;
    else
      s->session_state = SESSION_STATE_CLOSED;
  
    transport_close (session_get_transport_proto (s), s->connection_index,
  		   s->thread_index);
  }
  
  /**
   * Cleanup transport and session state.
   *
   * Notify transport of the cleanup and free the session. This should
   * be called only if transport reported some error and is already
   * closed.
   */
  void
  session_transport_cleanup (session_t * s)
  {
    s->session_state = SESSION_STATE_CLOSED;
  
    /* Delete from main lookup table before we axe the the transport */
    session_lookup_del_session (s);
    transport_cleanup (session_get_transport_proto (s), s->connection_index,
  		     s->thread_index);
    /* Since we called cleanup, no delete notification will come. So, make
     * sure the session is properly freed. */
    session_free_w_fifos (s);
  }
  
  /**
   * Allocate event queues in the shared-memory segment
   *
   * That can either be a newly created memfd segment, that will need to be
   * mapped by all stack users, or the binary api's svm region. The latter is
   * assumed to be already mapped. NOTE that this assumption DOES NOT hold if
   * api clients bootstrap shm api over sockets (i.e. use memfd segments) and
   * vpp uses api svm region for event queues.
   */
  void
  session_vpp_event_queues_allocate (session_main_t * smm)
  {
    u32 evt_q_length = 2048, evt_size = sizeof (session_event_t);
    ssvm_private_t *eqs = &smm->evt_qs_segment;
    api_main_t *am = &api_main;
    uword eqs_size = 64 << 20;
    pid_t vpp_pid = getpid ();
    void *oldheap;
    int i;
  
    if (smm->configured_event_queue_length)
      evt_q_length = smm->configured_event_queue_length;
  
    if (smm->evt_qs_use_memfd_seg)
      {
        if (smm->evt_qs_segment_size)
  	eqs_size = smm->evt_qs_segment_size;
  
        eqs->ssvm_size = eqs_size;
        eqs->i_am_master = 1;
        eqs->my_pid = vpp_pid;
        eqs->name = format (0, "%s%c", "evt-qs-segment", 0);
        eqs->requested_va = smm->session_baseva;
  
        if (ssvm_master_init (eqs, SSVM_SEGMENT_MEMFD))
  	{
  	  clib_warning ("failed to initialize queue segment");
  	  return;
  	}
      }
  
    if (smm->evt_qs_use_memfd_seg)
      oldheap = ssvm_push_heap (eqs->sh);
    else
      oldheap = svm_push_data_heap (am->vlib_rp);
  
    for (i = 0; i < vec_len (smm->wrk); i++)
      {
        svm_msg_q_cfg_t _cfg, *cfg = &_cfg;
        svm_msg_q_ring_cfg_t rc[SESSION_MQ_N_RINGS] = {
  	{evt_q_length, evt_size, 0}
  	,
  	{evt_q_length >> 1, 256, 0}
        };
        cfg->consumer_pid = 0;
        cfg->n_rings = 2;
        cfg->q_nitems = evt_q_length;
        cfg->ring_cfgs = rc;
        smm->wrk[i].vpp_event_queue = svm_msg_q_alloc (cfg);
        if (smm->evt_qs_use_memfd_seg)
  	{
  	  if (svm_msg_q_alloc_consumer_eventfd (smm->wrk[i].vpp_event_queue))
  	    clib_warning ("eventfd returned");
  	}
      }
  
    if (smm->evt_qs_use_memfd_seg)
      ssvm_pop_heap (oldheap);
    else
      svm_pop_heap (oldheap);
  }
  
  ssvm_private_t *
  session_main_get_evt_q_segment (void)
  {
    session_main_t *smm = &session_main;
    if (smm->evt_qs_use_memfd_seg)
      return &smm->evt_qs_segment;
    return 0;
  }
  
  u64
  session_segment_handle (session_t * s)
  {
    svm_fifo_t *f;
  
    if (s->session_state == SESSION_STATE_LISTENING)
      return SESSION_INVALID_HANDLE;
  
    f = s->rx_fifo;
    return segment_manager_make_segment_handle (f->segment_manager,
  					      f->segment_index);
  }
  
  /* *INDENT-OFF* */
  static session_fifo_rx_fn *session_tx_fns[TRANSPORT_TX_N_FNS] = {
      session_tx_fifo_peek_and_snd,
      session_tx_fifo_dequeue_and_snd,
      session_tx_fifo_dequeue_internal,
      session_tx_fifo_dequeue_and_snd
  };
  /* *INDENT-ON* */
  
  /**
   * Initialize session layer for given transport proto and ip version
   *
   * Allocates per session type (transport proto + ip version) data structures
   * and adds arc from session queue node to session type output node.
   */
  void
  session_register_transport (transport_proto_t transport_proto,
  			    const transport_proto_vft_t * vft, u8 is_ip4,
  			    u32 output_node)
  {
    session_main_t *smm = &session_main;
    session_type_t session_type;
    u32 next_index = ~0;
  
    session_type = session_type_from_proto_and_ip (transport_proto, is_ip4);
  
    vec_validate (smm->session_type_to_next, session_type);
    vec_validate (smm->session_tx_fns, session_type);
  
    /* *INDENT-OFF* */
    if (output_node != ~0)
      {
        foreach_vlib_main (({
            next_index = vlib_node_add_next (this_vlib_main,
                                             session_queue_node.index,
                                             output_node);
        }));
      }
    /* *INDENT-ON* */
  
    smm->session_type_to_next[session_type] = next_index;
    smm->session_tx_fns[session_type] = session_tx_fns[vft->tx_type];
  }
  
  transport_connection_t *
  session_get_transport (session_t * s)
  {
    if (s->session_state != SESSION_STATE_LISTENING)
      return transport_get_connection (session_get_transport_proto (s),
  				     s->connection_index, s->thread_index);
    else
      return transport_get_listener (session_get_transport_proto (s),
  				   s->connection_index);
  }
  
  transport_connection_t *
  listen_session_get_transport (session_t * s)
  {
    return transport_get_listener (session_get_transport_proto (s),
  				 s->connection_index);
  }
  
  void
  session_flush_frames_main_thread (vlib_main_t * vm)
  {
    ASSERT (vlib_get_thread_index () == 0);
    vlib_process_signal_event_mt (vm, session_queue_process_node.index,
  				SESSION_Q_PROCESS_FLUSH_FRAMES, 0);
  }
  
  static clib_error_t *
  session_manager_main_enable (vlib_main_t * vm)
  {
    segment_manager_main_init_args_t _sm_args = { 0 }, *sm_args = &_sm_args;
    session_main_t *smm = &session_main;
    vlib_thread_main_t *vtm = vlib_get_thread_main ();
    u32 num_threads, preallocated_sessions_per_worker;
    session_worker_t *wrk;
    int i;
  
    num_threads = 1 /* main thread */  + vtm->n_threads;
  
    if (num_threads < 1)
      return clib_error_return (0, "n_thread_stacks not set");
  
    /* Allocate cache line aligned worker contexts */
    vec_validate_aligned (smm->wrk, num_threads - 1, CLIB_CACHE_LINE_BYTES);
  
    for (i = 0; i < num_threads; i++)
      {
        wrk = &smm->wrk[i];
        vec_validate (wrk->free_event_vector, 128);
        _vec_len (wrk->free_event_vector) = 0;
        vec_validate (wrk->pending_event_vector, 128);
        _vec_len (wrk->pending_event_vector) = 0;
        vec_validate (wrk->pending_disconnects, 128);
        _vec_len (wrk->pending_disconnects) = 0;
        vec_validate (wrk->postponed_event_vector, 128);
        _vec_len (wrk->postponed_event_vector) = 0;
  
        wrk->last_vlib_time = vlib_time_now (vlib_mains[i]);
        wrk->dispatch_period = 500e-6;
  
        if (num_threads > 1)
  	clib_rwlock_init (&smm->wrk[i].peekers_rw_locks);
      }
  
  #if SESSION_DEBUG
    vec_validate (smm->last_event_poll_by_thread, num_threads - 1);
  #endif
  
    /* Allocate vpp event queues segment and queue */
    session_vpp_event_queues_allocate (smm);
  
    /* Initialize fifo segment main baseva and timeout */
    sm_args->baseva = smm->session_baseva + smm->evt_qs_segment_size;
    sm_args->size = smm->session_va_space_size;
    segment_manager_main_init (sm_args);
  
    /* Preallocate sessions */
    if (smm->preallocated_sessions)
      {
        if (num_threads == 1)
  	{
  	  pool_init_fixed (smm->wrk[0].sessions, smm->preallocated_sessions);
  	}
        else
  	{
  	  int j;
  	  preallocated_sessions_per_worker =
  	    (1.1 * (f64) smm->preallocated_sessions /
  	     (f64) (num_threads - 1));
  
  	  for (j = 1; j < num_threads; j++)
  	    {
  	      pool_init_fixed (smm->wrk[j].sessions,
  			       preallocated_sessions_per_worker);
  	    }
  	}
      }
  
    session_lookup_init ();
    app_namespaces_init ();
    transport_init ();
  
    smm->is_enabled = 1;
  
    /* Enable transports */
    transport_enable_disable (vm, 1);
    transport_init_tx_pacers_period ();
    return 0;
  }
  
  void
  session_node_enable_disable (u8 is_en)
  {
    u8 state = is_en ? VLIB_NODE_STATE_POLLING : VLIB_NODE_STATE_DISABLED;
    vlib_thread_main_t *vtm = vlib_get_thread_main ();
    u8 have_workers = vtm->n_threads != 0;
  
    /* *INDENT-OFF* */
    foreach_vlib_main (({
      if (have_workers && ii == 0)
        {
  	vlib_node_set_state (this_vlib_main, session_queue_process_node.index,
  	                     state);
  	if (is_en)
  	  {
  	    vlib_node_t *n = vlib_get_node (this_vlib_main,
  	                                    session_queue_process_node.index);
  	    vlib_start_process (this_vlib_main, n->runtime_index);
  	  }
  	else
  	  {
  	    vlib_process_signal_event_mt (this_vlib_main,
  	                                  session_queue_process_node.index,
  	                                  SESSION_Q_PROCESS_STOP, 0);
  	  }
  
  	continue;
        }
      vlib_node_set_state (this_vlib_main, session_queue_node.index,
                           state);
    }));
    /* *INDENT-ON* */
  }
  
  clib_error_t *
  vnet_session_enable_disable (vlib_main_t * vm, u8 is_en)
  {
    clib_error_t *error = 0;
    if (is_en)
      {
        if (session_main.is_enabled)
  	return 0;
  
        session_node_enable_disable (is_en);
        error = session_manager_main_enable (vm);
      }
    else
      {
        session_main.is_enabled = 0;
        session_node_enable_disable (is_en);
      }
  
    return error;
  }
  
  clib_error_t *
  session_manager_main_init (vlib_main_t * vm)
  {
    session_main_t *smm = &session_main;
    smm->session_baseva = HIGH_SEGMENT_BASEVA;
  #if (HIGH_SEGMENT_BASEVA > (4ULL << 30))
    smm->session_va_space_size = 128ULL << 30;
    smm->evt_qs_segment_size = 64 << 20;
  #else
    smm->session_va_space_size = 128 << 20;
    smm->evt_qs_segment_size = 1 << 20;
  #endif
    smm->is_enabled = 0;
    return 0;
  }
  
  VLIB_INIT_FUNCTION (session_manager_main_init);
  
  static clib_error_t *
  session_config_fn (vlib_main_t * vm, unformat_input_t * input)
  {
    session_main_t *smm = &session_main;
    u32 nitems;
    uword tmp;
  
    while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
      {
        if (unformat (input, "event-queue-length %d", &nitems))
  	{
  	  if (nitems >= 2048)
  	    smm->configured_event_queue_length = nitems;
  	  else
  	    clib_warning ("event queue length %d too small, ignored", nitems);
  	}
        else if (unformat (input, "preallocated-sessions %d",
  			 &smm->preallocated_sessions))
  	;
        else if (unformat (input, "v4-session-table-buckets %d",
  			 &smm->configured_v4_session_table_buckets))
  	;
        else if (unformat (input, "v4-halfopen-table-buckets %d",
  			 &smm->configured_v4_halfopen_table_buckets))
  	;
        else if (unformat (input, "v6-session-table-buckets %d",
  			 &smm->configured_v6_session_table_buckets))
  	;
        else if (unformat (input, "v6-halfopen-table-buckets %d",
  			 &smm->configured_v6_halfopen_table_buckets))
  	;
        else if (unformat (input, "v4-session-table-memory %U",
  			 unformat_memory_size, &tmp))
  	{
  	  if (tmp >= 0x100000000)
  	    return clib_error_return (0, "memory size %llx (%lld) too large",
  				      tmp, tmp);
  	  smm->configured_v4_session_table_memory = tmp;
  	}
        else if (unformat (input, "v4-halfopen-table-memory %U",
  			 unformat_memory_size, &tmp))
  	{
  	  if (tmp >= 0x100000000)
  	    return clib_error_return (0, "memory size %llx (%lld) too large",
  				      tmp, tmp);
  	  smm->configured_v4_halfopen_table_memory = tmp;
  	}
        else if (unformat (input, "v6-session-table-memory %U",
  			 unformat_memory_size, &tmp))
  	{
  	  if (tmp >= 0x100000000)
  	    return clib_error_return (0, "memory size %llx (%lld) too large",
  				      tmp, tmp);
  	  smm->configured_v6_session_table_memory = tmp;
  	}
        else if (unformat (input, "v6-halfopen-table-memory %U",
  			 unformat_memory_size, &tmp))
  	{
  	  if (tmp >= 0x100000000)
  	    return clib_error_return (0, "memory size %llx (%lld) too large",
  				      tmp, tmp);
  	  smm->configured_v6_halfopen_table_memory = tmp;
  	}
        else if (unformat (input, "local-endpoints-table-memory %U",
  			 unformat_memory_size, &tmp))
  	{
  	  if (tmp >= 0x100000000)
  	    return clib_error_return (0, "memory size %llx (%lld) too large",
  				      tmp, tmp);
  	  smm->local_endpoints_table_memory = tmp;
  	}
        else if (unformat (input, "local-endpoints-table-buckets %d",
  			 &smm->local_endpoints_table_buckets))
  	;
        else if (unformat (input, "evt_qs_memfd_seg"))
  	smm->evt_qs_use_memfd_seg = 1;
        else if (unformat (input, "evt_qs_seg_size %U", unformat_memory_size,
  			 &smm->evt_qs_segment_size))
  	;
        else
  	return clib_error_return (0, "unknown input `%U'",
  				  format_unformat_error, input);
      }
    return 0;
  }
  
  VLIB_CONFIG_FUNCTION (session_config_fn, "session");
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  