src/vnet/session/application_local.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 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.
  */

 #include <vnet/session/application_local.h>
 #include <vnet/session/session.h>

 static ct_connection_t *connections;

 static void
 ct_enable_disable_main_pre_input_node (u8 is_add)
 {
   u32 n_conns;

   if (!vlib_num_workers ())
     return;

   n_conns = pool_elts (connections);
   if (n_conns > 2)
     return;

   if (n_conns > 0 && is_add)
     vlib_node_set_state (vlib_get_main (),
 			 session_queue_pre_input_node.index,
 			 VLIB_NODE_STATE_POLLING);
   else if (n_conns == 0)
     vlib_node_set_state (vlib_get_main (),
 			 session_queue_pre_input_node.index,
 			 VLIB_NODE_STATE_DISABLED);
 }

 static ct_connection_t *
 ct_connection_alloc (void)
 {
   ct_connection_t *ct;

   pool_get_zero (connections, ct);
   ct->c_c_index = ct - connections;
   ct->c_thread_index = 0;
   ct->client_wrk = ~0;
   ct->server_wrk = ~0;
   return ct;
 }

 static ct_connection_t *
 ct_connection_get (u32 ct_index)
 {
   if (pool_is_free_index (connections, ct_index))
     return 0;
   return pool_elt_at_index (connections, ct_index);
 }

 static void
 ct_connection_free (ct_connection_t * ct)
 {
   if (CLIB_DEBUG)
     memset (ct, 0xfc, sizeof (*ct));
   pool_put (connections, ct);
 }

 session_t *
 ct_session_get_peer (session_t * s)
 {
   ct_connection_t *ct, *peer_ct;
   ct = ct_connection_get (s->connection_index);
   peer_ct = ct_connection_get (ct->peer_index);
   return session_get (peer_ct->c_s_index, 0);
 }

 void
 ct_session_endpoint (session_t * ll, session_endpoint_t * sep)
 {
   ct_connection_t *ct;
   ct = (ct_connection_t *) session_get_transport (ll);
   sep->transport_proto = ct->actual_tp;
   sep->port = ct->c_lcl_port;
   sep->is_ip4 = ct->c_is_ip4;
 }

 int
 ct_session_connect_notify (session_t * ss)
 {
   ct_connection_t *sct, *cct;
   app_worker_t *client_wrk;
   segment_manager_t *sm;
   fifo_segment_t *seg;
   u64 segment_handle;
   int is_fail = 0;
   session_t *cs;
   u32 ss_index;

   ss_index = ss->session_index;
   sct = (ct_connection_t *) session_get_transport (ss);
   client_wrk = app_worker_get (sct->client_wrk);

   sm = segment_manager_get (ss->rx_fifo->segment_manager);
   seg = segment_manager_get_segment_w_lock (sm, ss->rx_fifo->segment_index);
   segment_handle = segment_manager_segment_handle (sm, seg);

   if (app_worker_add_segment_notify (client_wrk, segment_handle))
     {
       clib_warning ("failed to notify client %u of new segment",
 		    sct->client_wrk);
       segment_manager_segment_reader_unlock (sm);
       session_close (ss);
       is_fail = 1;
     }
   else
     {
       segment_manager_segment_reader_unlock (sm);
     }

   /* Alloc client session */
   cct = ct_connection_get (sct->peer_index);

   cs = session_alloc (0);
   ss = session_get (ss_index, 0);
   cs->session_type = ss->session_type;
   cs->connection_index = sct->c_c_index;
   cs->listener_handle = SESSION_INVALID_HANDLE;
   cs->session_state = SESSION_STATE_CONNECTING;
   cs->app_wrk_index = client_wrk->wrk_index;
   cs->connection_index = cct->c_c_index;

   cct->c_s_index = cs->session_index;
   cct->client_rx_fifo = ss->tx_fifo;
   cct->client_tx_fifo = ss->rx_fifo;

   cct->client_rx_fifo->refcnt++;
   cct->client_tx_fifo->refcnt++;

   /* This will allocate fifos for the session. They won't be used for
    * exchanging data but they will be used to close the connection if
    * the segment manager/worker is freed */
   if (app_worker_init_connected (client_wrk, cs))
     {
       session_close (ss);
       return -1;
     }

   if (app_worker_connect_notify (client_wrk, is_fail ? 0 : cs,
 				 sct->client_opaque))
     {
       session_close (ss);
       return -1;
     }

   cs = session_get (cct->c_s_index, 0);
   cs->session_state = SESSION_STATE_READY;

   return 0;
 }

 static int
 ct_init_local_session (app_worker_t * client_wrk, app_worker_t * server_wrk,
 		       ct_connection_t * ct, session_t * ls, session_t * ll)
 {
   u32 round_rx_fifo_sz, round_tx_fifo_sz, sm_index, seg_size;
   segment_manager_props_t *props;
   application_t *server;
   segment_manager_t *sm;
   u32 margin = 16 << 10;
   fifo_segment_t *seg;
   u64 segment_handle;
   int seg_index, rv;

   server = application_get (server_wrk->app_index);

   props = application_segment_manager_properties (server);
   round_rx_fifo_sz = 1 << max_log2 (props->rx_fifo_size);
   round_tx_fifo_sz = 1 << max_log2 (props->tx_fifo_size);
   /* Increase size because of inefficient chunk allocations. Depending on
    * how data is consumed, it may happen that more chunks than needed are
    * allocated.
    * TODO should remove once allocations are done more efficiently */
   seg_size = 4 * (round_rx_fifo_sz + round_tx_fifo_sz + margin);

   sm = app_worker_get_listen_segment_manager (server_wrk, ll);
   seg_index = segment_manager_add_segment (sm, seg_size);
   if (seg_index < 0)
     {
       clib_warning ("failed to add new cut-through segment");
       return seg_index;
     }
   seg = segment_manager_get_segment_w_lock (sm, seg_index);

   rv = segment_manager_try_alloc_fifos (seg, ls->thread_index,
 					props->rx_fifo_size,
 					props->tx_fifo_size, &ls->rx_fifo,
 					&ls->tx_fifo);
   if (rv)
     {
       clib_warning ("failed to add fifos in cut-through segment");
       segment_manager_segment_reader_unlock (sm);
       goto failed;
     }

   sm_index = segment_manager_index (sm);
   ls->rx_fifo->master_session_index = ls->session_index;
   ls->tx_fifo->master_session_index = ls->session_index;
   ls->rx_fifo->segment_manager = sm_index;
   ls->tx_fifo->segment_manager = sm_index;
   ls->rx_fifo->segment_index = seg_index;
   ls->tx_fifo->segment_index = seg_index;

   segment_handle = segment_manager_segment_handle (sm, seg);
   if ((rv = app_worker_add_segment_notify (server_wrk, segment_handle)))
     {
       clib_warning ("failed to notify server of new segment");
       segment_manager_segment_reader_unlock (sm);
       goto failed;
     }
   segment_manager_segment_reader_unlock (sm);
   ct->segment_handle = segment_handle;

   return 0;

 failed:
   segment_manager_del_segment (sm, seg);
   return rv;
 }

 static int
 ct_connect (app_worker_t * client_wrk, session_t * ll,
 	    session_endpoint_cfg_t * sep)
 {
   u32 cct_index, ll_index, ll_ct_index;
   ct_connection_t *sct, *cct, *ll_ct;
   app_worker_t *server_wrk;
   session_t *ss;

   ll_index = ll->session_index;
   ll_ct_index = ll->connection_index;

   cct = ct_connection_alloc ();
   cct_index = cct->c_c_index;
   sct = ct_connection_alloc ();
   ll_ct = ct_connection_get (ll_ct_index);

   /*
    * Alloc and init client transport
    */
   cct = ct_connection_get (cct_index);
   cct->c_thread_index = 0;
   cct->c_rmt_port = sep->port;
   cct->c_lcl_port = 0;
   cct->c_is_ip4 = sep->is_ip4;
   clib_memcpy (&cct->c_rmt_ip, &sep->ip, sizeof (sep->ip));
   cct->actual_tp = ll_ct->actual_tp;
   cct->is_client = 1;

   /*
    * Init server transport
    */
   sct->c_thread_index = 0;
   sct->c_rmt_port = 0;
   sct->c_lcl_port = ll_ct->c_lcl_port;
   sct->c_is_ip4 = sep->is_ip4;
   clib_memcpy (&sct->c_lcl_ip, &ll_ct->c_lcl_ip, sizeof (ll_ct->c_lcl_ip));
   sct->client_wrk = client_wrk->wrk_index;
   sct->c_proto = TRANSPORT_PROTO_NONE;
   sct->client_opaque = sep->opaque;
   sct->actual_tp = ll_ct->actual_tp;

   sct->peer_index = cct->c_c_index;
   cct->peer_index = sct->c_c_index;

   /*
    * Accept server session. Client session is created only after
    * server confirms accept.
    */
   ss = session_alloc (0);
   ll = listen_session_get (ll_index);
   ss->session_type = session_type_from_proto_and_ip (TRANSPORT_PROTO_NONE,
 						     sct->c_is_ip4);
   ss->connection_index = sct->c_c_index;
   ss->listener_handle = listen_session_get_handle (ll);
   ss->session_state = SESSION_STATE_CREATED;

   server_wrk = application_listener_select_worker (ll);
   ss->app_wrk_index = server_wrk->wrk_index;

   sct->c_s_index = ss->session_index;
   sct->server_wrk = ss->app_wrk_index;

   if (ct_init_local_session (client_wrk, server_wrk, sct, ss, ll))
     {
       clib_warning ("failed");
       ct_connection_free (sct);
       session_free (ss);
       return -1;
     }

   ss->session_state = SESSION_STATE_ACCEPTING;
   if (app_worker_accept_notify (server_wrk, ss))
     {
       clib_warning ("failed");
       ct_connection_free (sct);
       session_free_w_fifos (ss);
       return -1;
     }

   cct->segment_handle = sct->segment_handle;
   ct_enable_disable_main_pre_input_node (1 /* is_add */ );
   return 0;
 }

 static u32
 ct_start_listen (u32 app_listener_index, transport_endpoint_t * tep)
 {
   session_endpoint_cfg_t *sep;
   ct_connection_t *ct;

   sep = (session_endpoint_cfg_t *) tep;
   ct = ct_connection_alloc ();
   ct->server_wrk = sep->app_wrk_index;
   ct->c_is_ip4 = sep->is_ip4;
   clib_memcpy (&ct->c_lcl_ip, &sep->ip, sizeof (sep->ip));
   ct->c_lcl_port = sep->port;
   ct->actual_tp = sep->transport_proto;
   ct_enable_disable_main_pre_input_node (1 /* is_add */ );
   return ct->c_c_index;
 }

 static u32
 ct_stop_listen (u32 ct_index)
 {
   ct_connection_t *ct;
   ct = ct_connection_get (ct_index);
   ct_connection_free (ct);
   ct_enable_disable_main_pre_input_node (0 /* is_add */ );
   return 0;
 }

 static transport_connection_t *
 ct_listener_get (u32 ct_index)
 {
   return (transport_connection_t *) ct_connection_get (ct_index);
 }

 static int
 ct_session_connect (transport_endpoint_cfg_t * tep)
 {
   session_endpoint_cfg_t *sep_ext;
   session_endpoint_t *sep;
   app_worker_t *app_wrk;
   session_handle_t lh;
   application_t *app;
   app_listener_t *al;
   u32 table_index;
   session_t *ll;
   u8 fib_proto;

   sep_ext = (session_endpoint_cfg_t *) tep;
   sep = (session_endpoint_t *) tep;
   app_wrk = app_worker_get (sep_ext->app_wrk_index);
   app = application_get (app_wrk->app_index);

   sep->transport_proto = sep_ext->original_tp;
   table_index = application_local_session_table (app);
   lh = session_lookup_local_endpoint (table_index, sep);
   if (lh == SESSION_DROP_HANDLE)
     return VNET_API_ERROR_APP_CONNECT_FILTERED;

   if (lh == SESSION_INVALID_HANDLE)
     goto global_scope;

   ll = listen_session_get_from_handle (lh);
   al = app_listener_get_w_session (ll);

   /*
    * Break loop if rule in local table points to connecting app. This
    * can happen if client is a generic proxy. Route connect through
    * global table instead.
    */
   if (al->app_index == app->app_index)
     goto global_scope;

   return ct_connect (app_wrk, ll, sep_ext);

   /*
    * If nothing found, check the global scope for locally attached
    * destinations. Make sure first that we're allowed to.
    */

 global_scope:
   if (session_endpoint_is_local (sep))
     return VNET_API_ERROR_SESSION_CONNECT;

   if (!application_has_global_scope (app))
     return VNET_API_ERROR_APP_CONNECT_SCOPE;

   fib_proto = session_endpoint_fib_proto (sep);
   table_index = session_lookup_get_index_for_fib (fib_proto, sep->fib_index);
   ll = session_lookup_listener_wildcard (table_index, sep);

   if (ll)
     return ct_connect (app_wrk, ll, sep_ext);

   /* Failed to connect but no error */
   return 1;
 }

 static void
 ct_session_close (u32 ct_index, u32 thread_index)
 {
   ct_connection_t *ct, *peer_ct;
   app_worker_t *app_wrk;
   session_t *s;

   ct = ct_connection_get (ct_index);
   peer_ct = ct_connection_get (ct->peer_index);
   if (peer_ct)
     {
       peer_ct->peer_index = ~0;
       session_transport_closing_notify (&peer_ct->connection);
     }

   s = session_get (ct->c_s_index, 0);
   app_wrk = app_worker_get_if_valid (s->app_wrk_index);
   if (app_wrk)
     app_worker_del_segment_notify (app_wrk, ct->segment_handle);
   session_free_w_fifos (s);
   if (ct->is_client)
     segment_manager_dealloc_fifos (ct->client_rx_fifo, ct->client_tx_fifo);

   ct_connection_free (ct);
   ct_enable_disable_main_pre_input_node (0 /* is_add */ );
 }

 static transport_connection_t *
 ct_session_get (u32 ct_index, u32 thread_index)
 {
   return (transport_connection_t *) ct_connection_get (ct_index);
 }

 static u8 *
 format_ct_connection_id (u8 * s, va_list * args)
 {
   ct_connection_t *ct = va_arg (*args, ct_connection_t *);
   if (!ct)
     return s;
   if (ct->c_is_ip4)
     {
       s = format (s, "[%d:%d][CT:%U] %U:%d->%U:%d", ct->c_thread_index,
 		  ct->c_s_index, format_transport_proto_short, ct->actual_tp,
 		  format_ip4_address, &ct->c_lcl_ip4,
 		  clib_net_to_host_u16 (ct->c_lcl_port), format_ip4_address,
 		  &ct->c_rmt_ip4, clib_net_to_host_u16 (ct->c_rmt_port));
     }
   else
     {
       s = format (s, "[%d:%d][CT:%U] %U:%d->%U:%d", ct->c_thread_index,
 		  ct->c_s_index, format_transport_proto_short, ct->actual_tp,
 		  format_ip6_address, &ct->c_lcl_ip6,
 		  clib_net_to_host_u16 (ct->c_lcl_port), format_ip6_address,
 		  &ct->c_rmt_ip6, clib_net_to_host_u16 (ct->c_rmt_port));
     }

   return s;
 }

 static int
 ct_custom_tx (void *session, u32 max_burst_size)
 {
   session_t *s = (session_t *) session;
   if (session_has_transport (s))
     return 0;
   return ct_session_tx (s);
 }

 static int
 ct_app_rx_evt (transport_connection_t * tc)
 {
   ct_connection_t *ct = (ct_connection_t *) tc, *peer_ct;
   session_t *ps;

   peer_ct = ct_connection_get (ct->peer_index);
   if (!peer_ct)
     return -1;
   ps = session_get (peer_ct->c_s_index, peer_ct->c_thread_index);
   return session_dequeue_notify (ps);
 }

 static u8 *
 format_ct_listener (u8 * s, va_list * args)
 {
   u32 tc_index = va_arg (*args, u32);
   u32 __clib_unused thread_index = va_arg (*args, u32);
   u32 __clib_unused verbose = va_arg (*args, u32);
   ct_connection_t *ct = ct_connection_get (tc_index);
   s = format (s, "%-50U", format_ct_connection_id, ct);
   if (verbose)
     s = format (s, "%-15s", "LISTEN");
   return s;
 }

 static u8 *
 format_ct_connection (u8 * s, va_list * args)
 {
   ct_connection_t *ct = va_arg (*args, ct_connection_t *);
   u32 verbose = va_arg (*args, u32);

   if (!ct)
     return s;
   s = format (s, "%-50U", format_ct_connection_id, ct);
   if (verbose)
     {
       s = format (s, "%-15s", "ESTABLISHED");
       if (verbose > 1)
 	{
 	  s = format (s, "\n");
 	}
     }
   return s;
 }

 static u8 *
 format_ct_session (u8 * s, va_list * args)
 {
   u32 ct_index = va_arg (*args, u32);
   u32 __clib_unused thread_index = va_arg (*args, u32);
   u32 verbose = va_arg (*args, u32);
   ct_connection_t *ct;

   ct = ct_connection_get (ct_index);
   if (!ct)
     {
       s = format (s, "empty\n");
       return s;
     }

   s = format (s, "%U", format_ct_connection, ct, verbose);
   return s;
 }

 /* *INDENT-OFF* */
 static const transport_proto_vft_t cut_thru_proto = {
   .start_listen = ct_start_listen,
   .stop_listen = ct_stop_listen,
   .get_listener = ct_listener_get,
   .connect = ct_session_connect,
   .close = ct_session_close,
   .get_connection = ct_session_get,
   .custom_tx = ct_custom_tx,
   .app_rx_evt = ct_app_rx_evt,
   .format_listener = format_ct_listener,
   .format_connection = format_ct_session,
   .transport_options = {
     .name = "ct",
     .short_name = "C",
     .tx_type = TRANSPORT_TX_INTERNAL,
     .service_type = TRANSPORT_SERVICE_APP,
   },
 };
 /* *INDENT-ON* */

 int
 ct_session_tx (session_t * s)
 {
   ct_connection_t *ct, *peer_ct;
   session_t *peer_s;

   ct = (ct_connection_t *) session_get_transport (s);
   peer_ct = ct_connection_get (ct->peer_index);
   if (!peer_ct)
     return -1;
   peer_s = session_get (peer_ct->c_s_index, 0);
   if (peer_s->session_state >= SESSION_STATE_TRANSPORT_CLOSING)
     return 0;
   return session_enqueue_notify (peer_s);
 }

 static clib_error_t *
 ct_transport_init (vlib_main_t * vm)
 {
   transport_register_protocol (TRANSPORT_PROTO_NONE, &cut_thru_proto,
 			       FIB_PROTOCOL_IP4, ~0);
   transport_register_protocol (TRANSPORT_PROTO_NONE, &cut_thru_proto,
 			       FIB_PROTOCOL_IP6, ~0);
   return 0;
 }

 VLIB_INIT_FUNCTION (ct_transport_init);

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

	#include <vnet/session/application_local.h>
	#include <vnet/session/session.h>

	static ct_connection_t *connections;

	static void
	ct_enable_disable_main_pre_input_node (u8 is_add)
	{
	u32 n_conns;

	if (!vlib_num_workers ())
	return;

	n_conns = pool_elts (connections);
	if (n_conns > 2)
	return;

	if (n_conns > 0 && is_add)
	vlib_node_set_state (vlib_get_main (),
	session_queue_pre_input_node.index,
	VLIB_NODE_STATE_POLLING);
	else if (n_conns == 0)
	vlib_node_set_state (vlib_get_main (),
	session_queue_pre_input_node.index,
	VLIB_NODE_STATE_DISABLED);
	}

	static ct_connection_t *
	ct_connection_alloc (void)
	{
	ct_connection_t *ct;

	pool_get_zero (connections, ct);
	ct->c_c_index = ct - connections;
	ct->c_thread_index = 0;
	ct->client_wrk = ~0;
	ct->server_wrk = ~0;
	return ct;
	}

	static ct_connection_t *
	ct_connection_get (u32 ct_index)
	{
	if (pool_is_free_index (connections, ct_index))
	return 0;
	return pool_elt_at_index (connections, ct_index);
	}

	static void
	ct_connection_free (ct_connection_t * ct)
	{
	if (CLIB_DEBUG)
	memset (ct, 0xfc, sizeof (*ct));
	pool_put (connections, ct);
	}

	session_t *
	ct_session_get_peer (session_t * s)
	{
	ct_connection_t ct, peer_ct;
	ct = ct_connection_get (s->connection_index);
	peer_ct = ct_connection_get (ct->peer_index);
	return session_get (peer_ct->c_s_index, 0);
	}

	void
	ct_session_endpoint (session_t * ll, session_endpoint_t * sep)
	{
	ct_connection_t *ct;
	ct = (ct_connection_t *) session_get_transport (ll);
	sep->transport_proto = ct->actual_tp;
	sep->port = ct->c_lcl_port;
	sep->is_ip4 = ct->c_is_ip4;
	}

	int
	ct_session_connect_notify (session_t * ss)
	{
	ct_connection_t sct, cct;
	app_worker_t *client_wrk;
	segment_manager_t *sm;
	fifo_segment_t *seg;
	u64 segment_handle;
	int is_fail = 0;
	session_t *cs;
	u32 ss_index;

	ss_index = ss->session_index;
	sct = (ct_connection_t *) session_get_transport (ss);
	client_wrk = app_worker_get (sct->client_wrk);

	sm = segment_manager_get (ss->rx_fifo->segment_manager);
	seg = segment_manager_get_segment_w_lock (sm, ss->rx_fifo->segment_index);
	segment_handle = segment_manager_segment_handle (sm, seg);

	if (app_worker_add_segment_notify (client_wrk, segment_handle))
	{
	clib_warning ("failed to notify client %u of new segment",
	sct->client_wrk);
	segment_manager_segment_reader_unlock (sm);
	session_close (ss);
	is_fail = 1;
	}
	else
	{
	segment_manager_segment_reader_unlock (sm);
	}

	/* Alloc client session */
	cct = ct_connection_get (sct->peer_index);

	cs = session_alloc (0);
	ss = session_get (ss_index, 0);
	cs->session_type = ss->session_type;
	cs->connection_index = sct->c_c_index;
	cs->listener_handle = SESSION_INVALID_HANDLE;
	cs->session_state = SESSION_STATE_CONNECTING;
	cs->app_wrk_index = client_wrk->wrk_index;
	cs->connection_index = cct->c_c_index;

	cct->c_s_index = cs->session_index;
	cct->client_rx_fifo = ss->tx_fifo;
	cct->client_tx_fifo = ss->rx_fifo;

	cct->client_rx_fifo->refcnt++;
	cct->client_tx_fifo->refcnt++;

	/* This will allocate fifos for the session. They won't be used for
	* exchanging data but they will be used to close the connection if
	* the segment manager/worker is freed */
	if (app_worker_init_connected (client_wrk, cs))
	{
	session_close (ss);
	return -1;
	}

	if (app_worker_connect_notify (client_wrk, is_fail ? 0 : cs,
	sct->client_opaque))
	{
	session_close (ss);
	return -1;
	}

	cs = session_get (cct->c_s_index, 0);
	cs->session_state = SESSION_STATE_READY;

	return 0;
	}

	static int
	ct_init_local_session (app_worker_t * client_wrk, app_worker_t * server_wrk,
	ct_connection_t * ct, session_t * ls, session_t * ll)
	{
	u32 round_rx_fifo_sz, round_tx_fifo_sz, sm_index, seg_size;
	segment_manager_props_t *props;
	application_t *server;
	segment_manager_t *sm;
	u32 margin = 16 << 10;
	fifo_segment_t *seg;
	u64 segment_handle;
	int seg_index, rv;

	server = application_get (server_wrk->app_index);

	props = application_segment_manager_properties (server);
	round_rx_fifo_sz = 1 << max_log2 (props->rx_fifo_size);
	round_tx_fifo_sz = 1 << max_log2 (props->tx_fifo_size);
	/* Increase size because of inefficient chunk allocations. Depending on
	* how data is consumed, it may happen that more chunks than needed are
	* allocated.
	* TODO should remove once allocations are done more efficiently */
	seg_size = 4 * (round_rx_fifo_sz + round_tx_fifo_sz + margin);

	sm = app_worker_get_listen_segment_manager (server_wrk, ll);
	seg_index = segment_manager_add_segment (sm, seg_size);
	if (seg_index < 0)
	{
	clib_warning ("failed to add new cut-through segment");
	return seg_index;
	}
	seg = segment_manager_get_segment_w_lock (sm, seg_index);

	rv = segment_manager_try_alloc_fifos (seg, ls->thread_index,
	props->rx_fifo_size,
	props->tx_fifo_size, &ls->rx_fifo,
	&ls->tx_fifo);
	if (rv)
	{
	clib_warning ("failed to add fifos in cut-through segment");
	segment_manager_segment_reader_unlock (sm);
	goto failed;
	}

	sm_index = segment_manager_index (sm);
	ls->rx_fifo->master_session_index = ls->session_index;
	ls->tx_fifo->master_session_index = ls->session_index;
	ls->rx_fifo->segment_manager = sm_index;
	ls->tx_fifo->segment_manager = sm_index;
	ls->rx_fifo->segment_index = seg_index;
	ls->tx_fifo->segment_index = seg_index;

	segment_handle = segment_manager_segment_handle (sm, seg);
	if ((rv = app_worker_add_segment_notify (server_wrk, segment_handle)))
	{
	clib_warning ("failed to notify server of new segment");
	segment_manager_segment_reader_unlock (sm);
	goto failed;
	}
	segment_manager_segment_reader_unlock (sm);
	ct->segment_handle = segment_handle;

	return 0;

	failed:
	segment_manager_del_segment (sm, seg);
	return rv;
	}

	static int
	ct_connect (app_worker_t * client_wrk, session_t * ll,
	session_endpoint_cfg_t * sep)
	{
	u32 cct_index, ll_index, ll_ct_index;
	ct_connection_t sct, cct, *ll_ct;
	app_worker_t *server_wrk;
	session_t *ss;

	ll_index = ll->session_index;
	ll_ct_index = ll->connection_index;

	cct = ct_connection_alloc ();
	cct_index = cct->c_c_index;
	sct = ct_connection_alloc ();
	ll_ct = ct_connection_get (ll_ct_index);

	/*
	* Alloc and init client transport
	*/
	cct = ct_connection_get (cct_index);
	cct->c_thread_index = 0;
	cct->c_rmt_port = sep->port;
	cct->c_lcl_port = 0;
	cct->c_is_ip4 = sep->is_ip4;
	clib_memcpy (&cct->c_rmt_ip, &sep->ip, sizeof (sep->ip));
	cct->actual_tp = ll_ct->actual_tp;
	cct->is_client = 1;

	/*
	* Init server transport
	*/
	sct->c_thread_index = 0;
	sct->c_rmt_port = 0;
	sct->c_lcl_port = ll_ct->c_lcl_port;
	sct->c_is_ip4 = sep->is_ip4;
	clib_memcpy (&sct->c_lcl_ip, &ll_ct->c_lcl_ip, sizeof (ll_ct->c_lcl_ip));
	sct->client_wrk = client_wrk->wrk_index;
	sct->c_proto = TRANSPORT_PROTO_NONE;
	sct->client_opaque = sep->opaque;
	sct->actual_tp = ll_ct->actual_tp;

	sct->peer_index = cct->c_c_index;
	cct->peer_index = sct->c_c_index;

	/*
	* Accept server session. Client session is created only after
	* server confirms accept.
	*/
	ss = session_alloc (0);
	ll = listen_session_get (ll_index);
	ss->session_type = session_type_from_proto_and_ip (TRANSPORT_PROTO_NONE,
	sct->c_is_ip4);
	ss->connection_index = sct->c_c_index;
	ss->listener_handle = listen_session_get_handle (ll);
	ss->session_state = SESSION_STATE_CREATED;

	server_wrk = application_listener_select_worker (ll);
	ss->app_wrk_index = server_wrk->wrk_index;

	sct->c_s_index = ss->session_index;
	sct->server_wrk = ss->app_wrk_index;

	if (ct_init_local_session (client_wrk, server_wrk, sct, ss, ll))
	{
	clib_warning ("failed");
	ct_connection_free (sct);
	session_free (ss);
	return -1;
	}

	ss->session_state = SESSION_STATE_ACCEPTING;
	if (app_worker_accept_notify (server_wrk, ss))
	{
	clib_warning ("failed");
	ct_connection_free (sct);
	session_free_w_fifos (ss);
	return -1;
	}

	cct->segment_handle = sct->segment_handle;
	ct_enable_disable_main_pre_input_node (1 /* is_add */ );
	return 0;
	}

	static u32
	ct_start_listen (u32 app_listener_index, transport_endpoint_t * tep)
	{
	session_endpoint_cfg_t *sep;
	ct_connection_t *ct;

	sep = (session_endpoint_cfg_t *) tep;
	ct = ct_connection_alloc ();
	ct->server_wrk = sep->app_wrk_index;
	ct->c_is_ip4 = sep->is_ip4;
	clib_memcpy (&ct->c_lcl_ip, &sep->ip, sizeof (sep->ip));
	ct->c_lcl_port = sep->port;
	ct->actual_tp = sep->transport_proto;
	ct_enable_disable_main_pre_input_node (1 /* is_add */ );
	return ct->c_c_index;
	}

	static u32
	ct_stop_listen (u32 ct_index)
	{
	ct_connection_t *ct;
	ct = ct_connection_get (ct_index);
	ct_connection_free (ct);
	ct_enable_disable_main_pre_input_node (0 /* is_add */ );
	return 0;
	}

	static transport_connection_t *
	ct_listener_get (u32 ct_index)
	{
	return (transport_connection_t *) ct_connection_get (ct_index);
	}

	static int
	ct_session_connect (transport_endpoint_cfg_t * tep)
	{
	session_endpoint_cfg_t *sep_ext;
	session_endpoint_t *sep;
	app_worker_t *app_wrk;
	session_handle_t lh;
	application_t *app;
	app_listener_t *al;
	u32 table_index;
	session_t *ll;
	u8 fib_proto;

	sep_ext = (session_endpoint_cfg_t *) tep;
	sep = (session_endpoint_t *) tep;
	app_wrk = app_worker_get (sep_ext->app_wrk_index);
	app = application_get (app_wrk->app_index);

	sep->transport_proto = sep_ext->original_tp;
	table_index = application_local_session_table (app);
	lh = session_lookup_local_endpoint (table_index, sep);
	if (lh == SESSION_DROP_HANDLE)
	return VNET_API_ERROR_APP_CONNECT_FILTERED;

	if (lh == SESSION_INVALID_HANDLE)
	goto global_scope;

	ll = listen_session_get_from_handle (lh);
	al = app_listener_get_w_session (ll);

	/*
	* Break loop if rule in local table points to connecting app. This
	* can happen if client is a generic proxy. Route connect through
	* global table instead.
	*/
	if (al->app_index == app->app_index)
	goto global_scope;

	return ct_connect (app_wrk, ll, sep_ext);

	/*
	* If nothing found, check the global scope for locally attached
	* destinations. Make sure first that we're allowed to.
	*/

	global_scope:
	if (session_endpoint_is_local (sep))
	return VNET_API_ERROR_SESSION_CONNECT;

	if (!application_has_global_scope (app))
	return VNET_API_ERROR_APP_CONNECT_SCOPE;

	fib_proto = session_endpoint_fib_proto (sep);
	table_index = session_lookup_get_index_for_fib (fib_proto, sep->fib_index);
	ll = session_lookup_listener_wildcard (table_index, sep);

	if (ll)
	return ct_connect (app_wrk, ll, sep_ext);

	/* Failed to connect but no error */
	return 1;
	}

	static void
	ct_session_close (u32 ct_index, u32 thread_index)
	{
	ct_connection_t ct, peer_ct;
	app_worker_t *app_wrk;
	session_t *s;

	ct = ct_connection_get (ct_index);
	peer_ct = ct_connection_get (ct->peer_index);
	if (peer_ct)
	{
	peer_ct->peer_index = ~0;
	session_transport_closing_notify (&peer_ct->connection);
	}

	s = session_get (ct->c_s_index, 0);
	app_wrk = app_worker_get_if_valid (s->app_wrk_index);
	if (app_wrk)
	app_worker_del_segment_notify (app_wrk, ct->segment_handle);
	session_free_w_fifos (s);
	if (ct->is_client)
	segment_manager_dealloc_fifos (ct->client_rx_fifo, ct->client_tx_fifo);

	ct_connection_free (ct);
	ct_enable_disable_main_pre_input_node (0 /* is_add */ );
	}

	static transport_connection_t *
	ct_session_get (u32 ct_index, u32 thread_index)
	{
	return (transport_connection_t *) ct_connection_get (ct_index);
	}

	static u8 *
	format_ct_connection_id (u8 * s, va_list * args)
	{
	ct_connection_t ct = va_arg (args, ct_connection_t *);
	if (!ct)
	return s;
	if (ct->c_is_ip4)
	{
	s = format (s, "[%d:%d][CT:%U] %U:%d->%U:%d", ct->c_thread_index,
	ct->c_s_index, format_transport_proto_short, ct->actual_tp,
	format_ip4_address, &ct->c_lcl_ip4,
	clib_net_to_host_u16 (ct->c_lcl_port), format_ip4_address,
	&ct->c_rmt_ip4, clib_net_to_host_u16 (ct->c_rmt_port));
	}
	else
	{
	s = format (s, "[%d:%d][CT:%U] %U:%d->%U:%d", ct->c_thread_index,
	ct->c_s_index, format_transport_proto_short, ct->actual_tp,
	format_ip6_address, &ct->c_lcl_ip6,
	clib_net_to_host_u16 (ct->c_lcl_port), format_ip6_address,
	&ct->c_rmt_ip6, clib_net_to_host_u16 (ct->c_rmt_port));
	}

	return s;
	}

	static int
	ct_custom_tx (void *session, u32 max_burst_size)
	{
	session_t s = (session_t ) session;
	if (session_has_transport (s))
	return 0;
	return ct_session_tx (s);
	}

	static int
	ct_app_rx_evt (transport_connection_t * tc)
	{
	ct_connection_t ct = (ct_connection_t ) tc, *peer_ct;
	session_t *ps;

	peer_ct = ct_connection_get (ct->peer_index);
	if (!peer_ct)
	return -1;
	ps = session_get (peer_ct->c_s_index, peer_ct->c_thread_index);
	return session_dequeue_notify (ps);
	}

	static u8 *
	format_ct_listener (u8 * s, va_list * args)
	{
	u32 tc_index = va_arg (*args, u32);
	u32 __clib_unused thread_index = va_arg (*args, u32);
	u32 __clib_unused verbose = va_arg (*args, u32);
	ct_connection_t *ct = ct_connection_get (tc_index);
	s = format (s, "%-50U", format_ct_connection_id, ct);
	if (verbose)
	s = format (s, "%-15s", "LISTEN");
	return s;
	}

	static u8 *
	format_ct_connection (u8 * s, va_list * args)
	{
	ct_connection_t ct = va_arg (args, ct_connection_t *);
	u32 verbose = va_arg (*args, u32);

	if (!ct)
	return s;
	s = format (s, "%-50U", format_ct_connection_id, ct);
	if (verbose)
	{
	s = format (s, "%-15s", "ESTABLISHED");
	if (verbose > 1)
	{
	s = format (s, "\n");
	}
	}
	return s;
	}

	static u8 *
	format_ct_session (u8 * s, va_list * args)
	{
	u32 ct_index = va_arg (*args, u32);
	u32 __clib_unused thread_index = va_arg (*args, u32);
	u32 verbose = va_arg (*args, u32);
	ct_connection_t *ct;

	ct = ct_connection_get (ct_index);
	if (!ct)
	{
	s = format (s, "empty\n");
	return s;
	}

	s = format (s, "%U", format_ct_connection, ct, verbose);
	return s;
	}

	/* INDENT-OFF */
	static const transport_proto_vft_t cut_thru_proto = {
	.start_listen = ct_start_listen,
	.stop_listen = ct_stop_listen,
	.get_listener = ct_listener_get,
	.connect = ct_session_connect,
	.close = ct_session_close,
	.get_connection = ct_session_get,
	.custom_tx = ct_custom_tx,
	.app_rx_evt = ct_app_rx_evt,
	.format_listener = format_ct_listener,
	.format_connection = format_ct_session,
	.transport_options = {
	.name = "ct",
	.short_name = "C",
	.tx_type = TRANSPORT_TX_INTERNAL,
	.service_type = TRANSPORT_SERVICE_APP,
	},
	};
	/* INDENT-ON */

	int
	ct_session_tx (session_t * s)
	{
	ct_connection_t ct, peer_ct;
	session_t *peer_s;

	ct = (ct_connection_t *) session_get_transport (s);
	peer_ct = ct_connection_get (ct->peer_index);
	if (!peer_ct)
	return -1;
	peer_s = session_get (peer_ct->c_s_index, 0);
	if (peer_s->session_state >= SESSION_STATE_TRANSPORT_CLOSING)
	return 0;
	return session_enqueue_notify (peer_s);
	}

	static clib_error_t *
	ct_transport_init (vlib_main_t * vm)
	{
	transport_register_protocol (TRANSPORT_PROTO_NONE, &cut_thru_proto,
	FIB_PROTOCOL_IP4, ~0);
	transport_register_protocol (TRANSPORT_PROTO_NONE, &cut_thru_proto,
	FIB_PROTOCOL_IP6, ~0);
	return 0;
	}

	VLIB_INIT_FUNCTION (ct_transport_init);

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