src/vnet/udp/udp_input.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2016-2019 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 <vlibmemory/api.h>
 #include <vlib/vlib.h>

 #include <vppinfra/hash.h>
 #include <vppinfra/error.h>
 #include <vppinfra/elog.h>

 #include <vnet/vnet.h>
 #include <vnet/ip/ip.h>
 #include <vnet/udp/udp.h>
 #include <vnet/udp/udp_packet.h>
 #include <vnet/session/session.h>

 static vlib_error_desc_t udp_error_counters[] = {
 #define udp_error(f, n, s, d) { #n, d, VL_COUNTER_SEVERITY_##s },
 #include "udp_error.def"
 #undef udp_error
 };

 typedef struct
 {
   u32 connection;
   u32 disposition;
   u32 thread_index;
 } udp_input_trace_t;

 /* packet trace format function */
 static u8 *
 format_udp_input_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   udp_input_trace_t *t = va_arg (*args, udp_input_trace_t *);

   s = format (s, "UDP_INPUT: connection %d, disposition %d, thread %d",
 	      t->connection, t->disposition, t->thread_index);
   return s;
 }

 #define foreach_udp_input_next			\
   _ (DROP, "error-drop")

 typedef enum
 {
 #define _(s, n) UDP_INPUT_NEXT_##s,
   foreach_udp_input_next
 #undef _
     UDP_INPUT_N_NEXT,
 } udp_input_next_t;

 always_inline void
 udp_input_inc_counter (vlib_main_t * vm, u8 is_ip4, u8 evt, u8 val)
 {
   if (is_ip4)
     vlib_node_increment_counter (vm, udp4_input_node.index, evt, val);
   else
     vlib_node_increment_counter (vm, udp6_input_node.index, evt, val);
 }

 #define udp_store_err_counters(vm, is_ip4, cnts)			\
 {									\
   int i;								\
   for (i = 0; i < UDP_N_ERROR; i++)					\
     if (cnts[i])							\
       udp_input_inc_counter(vm, is_ip4, i, cnts[i]);			\
 }

 #define udp_inc_err_counter(cnts, err, val)				\
 {									\
   cnts[err] += val;							\
 }

 static void
 udp_trace_buffer (vlib_main_t * vm, vlib_node_runtime_t * node,
 		  vlib_buffer_t * b, session_t * s, u16 error0)
 {
   udp_input_trace_t *t;

   if (PREDICT_TRUE (!(b->flags & VLIB_BUFFER_IS_TRACED)))
     return;

   t = vlib_add_trace (vm, node, b, sizeof (*t));
   t->connection = s ? s->connection_index : ~0;
   t->disposition = error0;
   t->thread_index = s ? s->thread_index : vm->thread_index;
 }

 static udp_connection_t *
 udp_connection_accept (udp_connection_t * listener, session_dgram_hdr_t * hdr,
 		       u32 thread_index)
 {
   udp_connection_t *uc;

   uc = udp_connection_alloc (thread_index);
   ip_copy (&uc->c_lcl_ip, &hdr->lcl_ip, hdr->is_ip4);
   ip_copy (&uc->c_rmt_ip, &hdr->rmt_ip, hdr->is_ip4);
   uc->c_lcl_port = hdr->lcl_port;
   uc->c_rmt_port = hdr->rmt_port;
   uc->c_is_ip4 = hdr->is_ip4;
   uc->c_fib_index = listener->c_fib_index;
   uc->mss = listener->mss;
   uc->flags |= UDP_CONN_F_CONNECTED;
   uc->cfg_flags = listener->cfg_flags;

   if (session_dgram_accept (&uc->connection, listener->c_s_index,
 			    listener->c_thread_index))
     {
       udp_connection_free (uc);
       return 0;
     }

   udp_connection_share_port (uc->c_lcl_port, uc->c_is_ip4);
   return uc;
 }

 static void
 udp_connection_enqueue (udp_connection_t * uc0, session_t * s0,
 			session_dgram_hdr_t * hdr0, u32 thread_index,
 			vlib_buffer_t * b, u8 queue_event, u32 * error0)
 {
   int wrote0;

   if (!(uc0->flags & UDP_CONN_F_CONNECTED))
     {
       clib_spinlock_lock (&uc0->rx_lock);

       wrote0 = session_enqueue_dgram_connection_cl (
 	s0, hdr0, b, TRANSPORT_PROTO_UDP, queue_event);

       clib_spinlock_unlock (&uc0->rx_lock);

       /* Expect cl udp enqueue to fail because fifo enqueue */
       if (PREDICT_FALSE (wrote0 == 0))
 	*error0 = UDP_ERROR_FIFO_FULL;

       return;
     }

   if (svm_fifo_max_enqueue_prod (s0->rx_fifo)
       < hdr0->data_length + sizeof (session_dgram_hdr_t))
     {
       *error0 = UDP_ERROR_FIFO_FULL;
       return;
     }

   /* If session is owned by another thread and rx event needed,
    * enqueue event now while we still have the peeker lock */
   if (s0->thread_index != thread_index)
     {
       wrote0 = session_enqueue_dgram_connection2 (
 	s0, hdr0, b, TRANSPORT_PROTO_UDP,
 	queue_event && !svm_fifo_has_event (s0->rx_fifo));
     }
   else
     {
       wrote0 = session_enqueue_dgram_connection (
 	s0, hdr0, b, TRANSPORT_PROTO_UDP, queue_event);
     }

   /* In some rare cases, session_enqueue_dgram_connection can fail because a
    * chunk cannot be allocated in the RX FIFO */
   if (PREDICT_FALSE (wrote0 == 0))
     *error0 = UDP_ERROR_FIFO_NOMEM;
 }

 always_inline session_t *
 udp_parse_and_lookup_buffer (vlib_buffer_t * b, session_dgram_hdr_t * hdr,
 			     u8 is_ip4)
 {
   udp_header_t *udp;
   u32 fib_index;
   session_t *s;

   /* udp_local hands us a pointer to the udp data */
   udp = (udp_header_t *) (vlib_buffer_get_current (b) - sizeof (*udp));
   fib_index = vnet_buffer (b)->ip.fib_index;

   hdr->data_offset = 0;
   hdr->lcl_port = udp->dst_port;
   hdr->rmt_port = udp->src_port;
   hdr->is_ip4 = is_ip4;
   hdr->gso_size = 0;

   if (is_ip4)
     {
       ip4_header_t *ip4;

       /* TODO: must fix once udp_local does ip options correctly */
       ip4 = (ip4_header_t *) (((u8 *) udp) - sizeof (*ip4));
       ip_set (&hdr->lcl_ip, &ip4->dst_address, 1);
       ip_set (&hdr->rmt_ip, &ip4->src_address, 1);
       hdr->data_length = clib_net_to_host_u16 (ip4->length);
       hdr->data_length -= sizeof (ip4_header_t) + sizeof (udp_header_t);
       s = session_lookup_safe4 (fib_index, &ip4->dst_address,
 				&ip4->src_address, udp->dst_port,
 				udp->src_port, TRANSPORT_PROTO_UDP);
     }
   else
     {
       ip6_header_t *ip60;

       ip60 = (ip6_header_t *) (((u8 *) udp) - sizeof (*ip60));
       ip_set (&hdr->lcl_ip, &ip60->dst_address, 0);
       ip_set (&hdr->rmt_ip, &ip60->src_address, 0);
       hdr->data_length = clib_net_to_host_u16 (ip60->payload_length);
       hdr->data_length -= sizeof (udp_header_t);
       s = session_lookup_safe6 (fib_index, &ip60->dst_address,
 				&ip60->src_address, udp->dst_port,
 				udp->src_port, TRANSPORT_PROTO_UDP);
     }

   /* Set the sw_if_index[VLIB_RX] to the interface we received
    * the connection on (the local interface) */
   vnet_buffer (b)->sw_if_index[VLIB_RX] = vnet_buffer (b)->ip.rx_sw_if_index;

   if (PREDICT_TRUE (!(b->flags & VLIB_BUFFER_NEXT_PRESENT)))
     b->current_length = hdr->data_length;
   else
     b->total_length_not_including_first_buffer = hdr->data_length
       - b->current_length;

   return s;
 }

 always_inline uword
 udp46_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 		    vlib_frame_t * frame, u8 is_ip4)
 {
   u32 thread_index = vm->thread_index, n_left_from, *from, *first_buffer;
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
   u16 err_counters[UDP_N_ERROR] = { 0 };

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

   b = bufs;

   while (n_left_from > 0)
     {
       u32 error0 = UDP_ERROR_ENQUEUED;
       session_dgram_hdr_t hdr0;
       udp_connection_t *uc0;
       session_t *s0;

       s0 = udp_parse_and_lookup_buffer (b[0], &hdr0, is_ip4);
       if (PREDICT_FALSE (!s0))
 	{
 	  error0 = UDP_ERROR_NO_LISTENER;
 	  goto done;
 	}

       if (s0->session_state == SESSION_STATE_OPENED)
 	{
 	  u8 queue_event = 1;
 	  uc0 = udp_connection_from_transport (session_get_transport (s0));
 	  uc0->sw_if_index = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
 	  if (uc0->flags & UDP_CONN_F_CONNECTED)
 	    {
 	      if (s0->thread_index != thread_index)
 		{
 		  /*
 		   * Clone the transport. It will be cleaned up with the
 		   * session once we notify the session layer.
 		   */
 		  uc0 = udp_connection_clone_safe (s0->connection_index,
 						   s0->thread_index);
 		  ASSERT (s0->session_index == uc0->c_s_index);

 		  /*
 		   * Ask session layer for a new session.
 		   */
 		  session_dgram_connect_notify (&uc0->connection,
 						s0->thread_index, &s0);
 		  queue_event = 0;
 		}
 	      else
 		s0->session_state = SESSION_STATE_READY;
 	    }
 	  udp_connection_enqueue (uc0, s0, &hdr0, thread_index, b[0],
 				  queue_event, &error0);
 	}
       else if (s0->session_state == SESSION_STATE_READY ||
 	       s0->session_state == SESSION_STATE_ACCEPTING)
 	{
 	  uc0 = udp_connection_from_transport (session_get_transport (s0));
 	  udp_connection_enqueue (uc0, s0, &hdr0, thread_index, b[0], 1,
 				  &error0);
 	}
       else if (s0->session_state == SESSION_STATE_LISTENING)
 	{
 	  uc0 = udp_connection_from_transport (session_get_transport (s0));
 	  if (uc0->flags & UDP_CONN_F_CONNECTED)
 	    {
 	      uc0 = udp_connection_accept (uc0, &hdr0, thread_index);
 	      if (!uc0)
 		{
 		  error0 = UDP_ERROR_CREATE_SESSION;
 		  goto done;
 		}
 	      s0 = session_get (uc0->c_s_index, uc0->c_thread_index);
 	      uc0->sw_if_index = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
 	      error0 = UDP_ERROR_ACCEPT;
 	    }
 	  udp_connection_enqueue (uc0, s0, &hdr0, thread_index, b[0], 1,
 				  &error0);
 	}
       else
 	{
 	  error0 = UDP_ERROR_NOT_READY;
 	}

     done:
       if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
 	udp_trace_buffer (vm, node, b[0], s0, error0);

       b += 1;
       n_left_from -= 1;

       udp_inc_err_counter (err_counters, error0, 1);
     }

   vlib_buffer_free (vm, first_buffer, frame->n_vectors);
   session_main_flush_enqueue_events (TRANSPORT_PROTO_UDP, thread_index);
   udp_store_err_counters (vm, is_ip4, err_counters);
   return frame->n_vectors;
 }

 static uword
 udp4_input (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    vlib_frame_t * frame)
 {
   return udp46_input_inline (vm, node, frame, 1);
 }

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (udp4_input_node) =
 {
   .function = udp4_input,
   .name = "udp4-input",
   .vector_size = sizeof (u32),
   .format_trace = format_udp_input_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
   .n_errors = UDP_N_ERROR,
   .error_counters = udp_error_counters,
   .n_next_nodes = UDP_INPUT_N_NEXT,
   .next_nodes = {
 #define _(s, n) [UDP_INPUT_NEXT_##s] = n,
       foreach_udp_input_next
 #undef _
   },
 };
 /* *INDENT-ON* */

 static uword
 udp6_input (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    vlib_frame_t * frame)
 {
   return udp46_input_inline (vm, node, frame, 0);
 }

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (udp6_input_node) =
 {
   .function = udp6_input,
   .name = "udp6-input",
   .vector_size = sizeof (u32),
   .format_trace = format_udp_input_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
   .n_errors = UDP_N_ERROR,
   .error_counters = udp_error_counters,
   .n_next_nodes = UDP_INPUT_N_NEXT,
   .next_nodes = {
 #define _(s, n) [UDP_INPUT_NEXT_##s] = n,
       foreach_udp_input_next
 #undef _
   },
 };
 /* *INDENT-ON* */

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2016-2019 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 <vlibmemory/api.h>
	#include <vlib/vlib.h>

	#include <vppinfra/hash.h>
	#include <vppinfra/error.h>
	#include <vppinfra/elog.h>

	#include <vnet/vnet.h>
	#include <vnet/ip/ip.h>
	#include <vnet/udp/udp.h>
	#include <vnet/udp/udp_packet.h>
	#include <vnet/session/session.h>

	static vlib_error_desc_t udp_error_counters[] = {
	#define udp_error(f, n, s, d) { #n, d, VL_COUNTER_SEVERITY_##s },
	#include "udp_error.def"
	#undef udp_error
	};

	typedef struct
	{
	u32 connection;
	u32 disposition;
	u32 thread_index;
	} udp_input_trace_t;

	/* packet trace format function */
	static u8 *
	format_udp_input_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	udp_input_trace_t t = va_arg (args, udp_input_trace_t *);

	s = format (s, "UDP_INPUT: connection %d, disposition %d, thread %d",
	t->connection, t->disposition, t->thread_index);
	return s;
	}

	#define foreach_udp_input_next \
	_ (DROP, "error-drop")

	typedef enum
	{
	#define _(s, n) UDP_INPUT_NEXT_##s,
	foreach_udp_input_next
	#undef _
	UDP_INPUT_N_NEXT,
	} udp_input_next_t;

	always_inline void
	udp_input_inc_counter (vlib_main_t * vm, u8 is_ip4, u8 evt, u8 val)
	{
	if (is_ip4)
	vlib_node_increment_counter (vm, udp4_input_node.index, evt, val);
	else
	vlib_node_increment_counter (vm, udp6_input_node.index, evt, val);
	}

	#define udp_store_err_counters(vm, is_ip4, cnts) \
	{ \
	int i; \
	for (i = 0; i < UDP_N_ERROR; i++) \
	if (cnts[i]) \
	udp_input_inc_counter(vm, is_ip4, i, cnts[i]); \
	}

	#define udp_inc_err_counter(cnts, err, val) \
	{ \
	cnts[err] += val; \
	}

	static void
	udp_trace_buffer (vlib_main_t * vm, vlib_node_runtime_t * node,
	vlib_buffer_t * b, session_t * s, u16 error0)
	{
	udp_input_trace_t *t;

	if (PREDICT_TRUE (!(b->flags & VLIB_BUFFER_IS_TRACED)))
	return;

	t = vlib_add_trace (vm, node, b, sizeof (*t));
	t->connection = s ? s->connection_index : ~0;
	t->disposition = error0;
	t->thread_index = s ? s->thread_index : vm->thread_index;
	}

	static udp_connection_t *
	udp_connection_accept (udp_connection_t * listener, session_dgram_hdr_t * hdr,
	u32 thread_index)
	{
	udp_connection_t *uc;

	uc = udp_connection_alloc (thread_index);
	ip_copy (&uc->c_lcl_ip, &hdr->lcl_ip, hdr->is_ip4);
	ip_copy (&uc->c_rmt_ip, &hdr->rmt_ip, hdr->is_ip4);
	uc->c_lcl_port = hdr->lcl_port;
	uc->c_rmt_port = hdr->rmt_port;
	uc->c_is_ip4 = hdr->is_ip4;
	uc->c_fib_index = listener->c_fib_index;
	uc->mss = listener->mss;
	uc->flags \|= UDP_CONN_F_CONNECTED;
	uc->cfg_flags = listener->cfg_flags;

	if (session_dgram_accept (&uc->connection, listener->c_s_index,
	listener->c_thread_index))
	{
	udp_connection_free (uc);
	return 0;
	}

	udp_connection_share_port (uc->c_lcl_port, uc->c_is_ip4);
	return uc;
	}

	static void
	udp_connection_enqueue (udp_connection_t * uc0, session_t * s0,
	session_dgram_hdr_t * hdr0, u32 thread_index,
	vlib_buffer_t * b, u8 queue_event, u32 * error0)
	{
	int wrote0;

	if (!(uc0->flags & UDP_CONN_F_CONNECTED))
	{
	clib_spinlock_lock (&uc0->rx_lock);

	wrote0 = session_enqueue_dgram_connection_cl (
	s0, hdr0, b, TRANSPORT_PROTO_UDP, queue_event);

	clib_spinlock_unlock (&uc0->rx_lock);

	/* Expect cl udp enqueue to fail because fifo enqueue */
	if (PREDICT_FALSE (wrote0 == 0))
	*error0 = UDP_ERROR_FIFO_FULL;

	return;
	}

	if (svm_fifo_max_enqueue_prod (s0->rx_fifo)
	< hdr0->data_length + sizeof (session_dgram_hdr_t))
	{
	*error0 = UDP_ERROR_FIFO_FULL;
	return;
	}

	/* If session is owned by another thread and rx event needed,
	* enqueue event now while we still have the peeker lock */
	if (s0->thread_index != thread_index)
	{
	wrote0 = session_enqueue_dgram_connection2 (
	s0, hdr0, b, TRANSPORT_PROTO_UDP,
	queue_event && !svm_fifo_has_event (s0->rx_fifo));
	}
	else
	{
	wrote0 = session_enqueue_dgram_connection (
	s0, hdr0, b, TRANSPORT_PROTO_UDP, queue_event);
	}

	/* In some rare cases, session_enqueue_dgram_connection can fail because a
	* chunk cannot be allocated in the RX FIFO */
	if (PREDICT_FALSE (wrote0 == 0))
	*error0 = UDP_ERROR_FIFO_NOMEM;
	}

	always_inline session_t *
	udp_parse_and_lookup_buffer (vlib_buffer_t * b, session_dgram_hdr_t * hdr,
	u8 is_ip4)
	{
	udp_header_t *udp;
	u32 fib_index;
	session_t *s;

	/* udp_local hands us a pointer to the udp data */
	udp = (udp_header_t ) (vlib_buffer_get_current (b) - sizeof (udp));
	fib_index = vnet_buffer (b)->ip.fib_index;

	hdr->data_offset = 0;
	hdr->lcl_port = udp->dst_port;
	hdr->rmt_port = udp->src_port;
	hdr->is_ip4 = is_ip4;
	hdr->gso_size = 0;

	if (is_ip4)
	{
	ip4_header_t *ip4;

	/* TODO: must fix once udp_local does ip options correctly */
	ip4 = (ip4_header_t ) (((u8 ) udp) - sizeof (*ip4));
	ip_set (&hdr->lcl_ip, &ip4->dst_address, 1);
	ip_set (&hdr->rmt_ip, &ip4->src_address, 1);
	hdr->data_length = clib_net_to_host_u16 (ip4->length);
	hdr->data_length -= sizeof (ip4_header_t) + sizeof (udp_header_t);
	s = session_lookup_safe4 (fib_index, &ip4->dst_address,
	&ip4->src_address, udp->dst_port,
	udp->src_port, TRANSPORT_PROTO_UDP);
	}
	else
	{
	ip6_header_t *ip60;

	ip60 = (ip6_header_t ) (((u8 ) udp) - sizeof (*ip60));
	ip_set (&hdr->lcl_ip, &ip60->dst_address, 0);
	ip_set (&hdr->rmt_ip, &ip60->src_address, 0);
	hdr->data_length = clib_net_to_host_u16 (ip60->payload_length);
	hdr->data_length -= sizeof (udp_header_t);
	s = session_lookup_safe6 (fib_index, &ip60->dst_address,
	&ip60->src_address, udp->dst_port,
	udp->src_port, TRANSPORT_PROTO_UDP);
	}

	/* Set the sw_if_index[VLIB_RX] to the interface we received
	* the connection on (the local interface) */
	vnet_buffer (b)->sw_if_index[VLIB_RX] = vnet_buffer (b)->ip.rx_sw_if_index;

	if (PREDICT_TRUE (!(b->flags & VLIB_BUFFER_NEXT_PRESENT)))
	b->current_length = hdr->data_length;
	else
	b->total_length_not_including_first_buffer = hdr->data_length
	- b->current_length;

	return s;
	}

	always_inline uword
	udp46_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
	vlib_frame_t * frame, u8 is_ip4)
	{
	u32 thread_index = vm->thread_index, n_left_from, from, first_buffer;
	vlib_buffer_t bufs[VLIB_FRAME_SIZE], *b;
	u16 err_counters[UDP_N_ERROR] = { 0 };

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

	b = bufs;

	while (n_left_from > 0)
	{
	u32 error0 = UDP_ERROR_ENQUEUED;
	session_dgram_hdr_t hdr0;
	udp_connection_t *uc0;
	session_t *s0;

	s0 = udp_parse_and_lookup_buffer (b[0], &hdr0, is_ip4);
	if (PREDICT_FALSE (!s0))
	{
	error0 = UDP_ERROR_NO_LISTENER;
	goto done;
	}

	if (s0->session_state == SESSION_STATE_OPENED)
	{
	u8 queue_event = 1;
	uc0 = udp_connection_from_transport (session_get_transport (s0));
	uc0->sw_if_index = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
	if (uc0->flags & UDP_CONN_F_CONNECTED)
	{
	if (s0->thread_index != thread_index)
	{
	/*
	* Clone the transport. It will be cleaned up with the
	* session once we notify the session layer.
	*/
	uc0 = udp_connection_clone_safe (s0->connection_index,
	s0->thread_index);
	ASSERT (s0->session_index == uc0->c_s_index);

	/*
	* Ask session layer for a new session.
	*/
	session_dgram_connect_notify (&uc0->connection,
	s0->thread_index, &s0);
	queue_event = 0;
	}
	else
	s0->session_state = SESSION_STATE_READY;
	}
	udp_connection_enqueue (uc0, s0, &hdr0, thread_index, b[0],
	queue_event, &error0);
	}
	else if (s0->session_state == SESSION_STATE_READY \|\|
	s0->session_state == SESSION_STATE_ACCEPTING)
	{
	uc0 = udp_connection_from_transport (session_get_transport (s0));
	udp_connection_enqueue (uc0, s0, &hdr0, thread_index, b[0], 1,
	&error0);
	}
	else if (s0->session_state == SESSION_STATE_LISTENING)
	{
	uc0 = udp_connection_from_transport (session_get_transport (s0));
	if (uc0->flags & UDP_CONN_F_CONNECTED)
	{
	uc0 = udp_connection_accept (uc0, &hdr0, thread_index);
	if (!uc0)
	{
	error0 = UDP_ERROR_CREATE_SESSION;
	goto done;
	}
	s0 = session_get (uc0->c_s_index, uc0->c_thread_index);
	uc0->sw_if_index = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
	error0 = UDP_ERROR_ACCEPT;
	}
	udp_connection_enqueue (uc0, s0, &hdr0, thread_index, b[0], 1,
	&error0);
	}
	else
	{
	error0 = UDP_ERROR_NOT_READY;
	}

	done:
	if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
	udp_trace_buffer (vm, node, b[0], s0, error0);

	b += 1;
	n_left_from -= 1;

	udp_inc_err_counter (err_counters, error0, 1);
	}

	vlib_buffer_free (vm, first_buffer, frame->n_vectors);
	session_main_flush_enqueue_events (TRANSPORT_PROTO_UDP, thread_index);
	udp_store_err_counters (vm, is_ip4, err_counters);
	return frame->n_vectors;
	}

	static uword
	udp4_input (vlib_main_t * vm, vlib_node_runtime_t * node,
	vlib_frame_t * frame)
	{
	return udp46_input_inline (vm, node, frame, 1);
	}

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (udp4_input_node) =
	{
	.function = udp4_input,
	.name = "udp4-input",
	.vector_size = sizeof (u32),
	.format_trace = format_udp_input_trace,
	.type = VLIB_NODE_TYPE_INTERNAL,
	.n_errors = UDP_N_ERROR,
	.error_counters = udp_error_counters,
	.n_next_nodes = UDP_INPUT_N_NEXT,
	.next_nodes = {
	#define _(s, n) [UDP_INPUT_NEXT_##s] = n,
	foreach_udp_input_next
	#undef _
	},
	};
	/* INDENT-ON */

	static uword
	udp6_input (vlib_main_t * vm, vlib_node_runtime_t * node,
	vlib_frame_t * frame)
	{
	return udp46_input_inline (vm, node, frame, 0);
	}

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (udp6_input_node) =
	{
	.function = udp6_input,
	.name = "udp6-input",
	.vector_size = sizeof (u32),
	.format_trace = format_udp_input_trace,
	.type = VLIB_NODE_TYPE_INTERNAL,
	.n_errors = UDP_N_ERROR,
	.error_counters = udp_error_counters,
	.n_next_nodes = UDP_INPUT_N_NEXT,
	.next_nodes = {
	#define _(s, n) [UDP_INPUT_NEXT_##s] = n,
	foreach_udp_input_next
	#undef _
	},
	};
	/* INDENT-ON */

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