FreeRTOS-Plus/Demo/FreeRTOS_Plus_TCP_Minimal_Windows_Simulator/DemoTasks/SimpleUDPClientAndServer.c - third_party/github/FreeRTOS/FreeRTOS-Kernel - Git at Google

 /*
  * FreeRTOS Kernel V10.3.0
  * Copyright (C) 2017 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
  * this software and associated documentation files (the "Software"), to deal in
  * the Software without restriction, including without limitation the rights to
  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
  * the Software, and to permit persons to whom the Software is furnished to do so,
  * subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in all
  * copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
  * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
  * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  * http://www.FreeRTOS.org
  * http://aws.amazon.com/freertos
  *
  * 1 tab == 4 spaces!
  */

 /*
  * Creates two transmitting tasks and two receiving tasks.  The transmitting
  * tasks send values that are received by the receiving tasks.  One set of tasks
  * uses the standard API.  The other set of tasks uses the zero copy API.
  *
  * See the following web page for essential demo usage and configuration
  * details:
  * http://www.FreeRTOS.org/FreeRTOS-Plus/FreeRTOS_Plus_TCP/examples_FreeRTOS_simulator.html
  */

 /* Standard includes. */
 #include <stdint.h>
 #include <stdio.h>

 /* FreeRTOS includes. */
 #include "FreeRTOS.h"
 #include "task.h"

 /* FreeRTOS+TCP includes. */
 #include "FreeRTOS_IP.h"
 #include "FreeRTOS_Sockets.h"

 #define simpTINY_DELAY	( ( TickType_t ) 2 )

 /*
  * Uses a socket to send data without using the zero copy option.
  * prvSimpleServerTask() will receive the data.
  */
 static void prvSimpleClientTask( void *pvParameters );

 /*
  * Uses a socket to receive the data sent by the prvSimpleClientTask() task.
  * Does not use the zero copy option.
  */
 static void prvSimpleServerTask( void *pvParameters );

 /*
  * Uses a socket to send data using the zero copy option.
  * prvSimpleZeroCopyServerTask() will receive the data.
  */
 static void prvSimpleZeroCopyUDPClientTask( void *pvParameters );

 /*
  * Uses a socket to receive the data sent by the prvSimpleZeroCopyUDPClientTask()
  * task.  Uses the zero copy option.
  */
 static void prvSimpleZeroCopyServerTask( void *pvParameters );

 /*-----------------------------------------------------------*/

 void vStartSimpleUDPClientServerTasks( uint16_t usStackSize, uint32_t ulPort, UBaseType_t uxPriority )
 {
 	/* Create the client and server tasks that do not use the zero copy
 	interface. */
 	xTaskCreate( prvSimpleClientTask, "SimpCpyClnt", usStackSize, ( void * ) ulPort, uxPriority, NULL );
 	xTaskCreate( prvSimpleServerTask, "SimpCpySrv", usStackSize, ( void * ) ulPort, uxPriority + 1, NULL );

 	/* Create the client and server tasks that do use the zero copy interface. */
 	xTaskCreate( prvSimpleZeroCopyUDPClientTask, "SimpZCpyClnt", usStackSize, ( void * ) ( ulPort + 1 ), uxPriority, NULL );
 	xTaskCreate( prvSimpleZeroCopyServerTask, "SimpZCpySrv", usStackSize, ( void * ) ( ulPort + 1 ), uxPriority + 1, NULL );
 }
 /*-----------------------------------------------------------*/

 static void prvSimpleClientTask( void *pvParameters )
 {
 Socket_t xClientSocket;
 struct freertos_sockaddr xDestinationAddress;
 uint8_t cString[ 65 ];
 BaseType_t lReturned;
 uint32_t ulCount = 0UL, ulIPAddress;
 const uint32_t ulLoopsPerSocket = 10UL;
 const TickType_t x150ms = 150UL / portTICK_PERIOD_MS;

 	/* Remove compiler warning about unused parameters. */
 	( void ) pvParameters;

 	/* It is assumed that this task is not created until the network is up,
 	so the IP address can be obtained immediately.  store the IP address being
 	used in ulIPAddress.  This is done so the socket can send to a different
 	port on the same IP address. */
 	FreeRTOS_GetAddressConfiguration( &ulIPAddress, NULL, NULL, NULL );

 	/* This test sends to itself, so data sent from here is received by a server
 	socket on the same IP address.  Setup the freertos_sockaddr structure with
 	this nodes IP address, and the port number being sent to.  The strange
 	casting is to try and remove compiler warnings on 32 bit machines. */
 	xDestinationAddress.sin_addr = ulIPAddress;
 	xDestinationAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
 	xDestinationAddress.sin_port = FreeRTOS_htons( xDestinationAddress.sin_port );

 	for( ;; )
 	{
 		/* Create the socket. */
 		xClientSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
 		configASSERT( xClientSocket != FREERTOS_INVALID_SOCKET );

 		/* The count is used to differentiate between different messages sent to
 		the server, and to break out of the do while loop below. */
 		ulCount = 0UL;

 		do
 		{
 			/* Create the string that is sent to the server. */
 			sprintf( ( char * ) cString, "Server received (not zero copy): Message number %lu\r\n", ulCount );

 			/* Send the string to the socket.  ulFlags is set to 0, so the zero
 			copy option is not selected.  That means the data from cString[] is
 			copied into a network buffer inside FreeRTOS_sendto(), and cString[]
 			can be reused as soon as FreeRTOS_sendto() has returned. */
 			lReturned = FreeRTOS_sendto( xClientSocket, ( void * ) cString, strlen( ( const char * ) cString ), 0, &xDestinationAddress, sizeof( xDestinationAddress ) );

 			ulCount++;

 		} while( ( lReturned != FREERTOS_SOCKET_ERROR ) && ( ulCount < ulLoopsPerSocket ) );

 		FreeRTOS_closesocket( xClientSocket );

 		/* A short delay to prevent the messages printed by the server task
 		scrolling off the screen too quickly, and to prevent reduce the network
 		loading. */
 		vTaskDelay( x150ms );
 	}
 }
 /*-----------------------------------------------------------*/

 static void prvSimpleServerTask( void *pvParameters )
 {
 int32_t lBytes;
 uint8_t cReceivedString[ 60 ];
 struct freertos_sockaddr xClient, xBindAddress;
 uint32_t xClientLength = sizeof( xClient );
 Socket_t xListeningSocket;

 	/* Just to prevent compiler warnings. */
 	( void ) pvParameters;

 	/* Attempt to open the socket. */
 	xListeningSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
 	configASSERT( xListeningSocket != FREERTOS_INVALID_SOCKET );

 	/* This test receives data sent from a different port on the same IP
 	address.  Configure the freertos_sockaddr structure with the address being
 	bound to.  The strange casting is to try and remove	compiler warnings on 32
 	bit machines.  Note that this task is only created after the network is up,
 	so the IP address is valid here. */
 	xBindAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
 	xBindAddress.sin_port = FreeRTOS_htons( xBindAddress.sin_port );

 	/* Bind the socket to the port that the client task will send to. */
 	FreeRTOS_bind( xListeningSocket, &xBindAddress, sizeof( xBindAddress ) );

 	for( ;; )
 	{
 		/* Zero out the receive array so there is NULL at the end of the string
 		when it is printed out. */
 		memset( cReceivedString, 0x00, sizeof( cReceivedString ) );

 		/* Receive data on the socket.  ulFlags is zero, so the zero copy option
 		is not set and the received data is copied into the buffer pointed to by
 		cReceivedString.  By default the block time is portMAX_DELAY.
 		xClientLength is not actually used by FreeRTOS_recvfrom(), but is set
 		appropriately in case future versions do use it. */
 		lBytes = FreeRTOS_recvfrom( xListeningSocket, cReceivedString, sizeof( cReceivedString ), 0, &xClient, &xClientLength );

 		/* Error check. */
 		configASSERT( lBytes == ( BaseType_t ) strlen( ( const char * ) cReceivedString ) );
 	}
 }
 /*-----------------------------------------------------------*/

 static void prvSimpleZeroCopyUDPClientTask( void *pvParameters )
 {
 Socket_t xClientSocket;
 uint8_t *pucUDPPayloadBuffer;
 struct freertos_sockaddr xDestinationAddress;
 BaseType_t lReturned;
 uint32_t ulCount = 0UL, ulIPAddress;
 const uint32_t ulLoopsPerSocket = 10UL;
 const char *pcStringToSend = "Server received (using zero copy): Message number ";
 const TickType_t x150ms = 150UL / portTICK_PERIOD_MS;
 /* 15 is added to ensure the number, \r\n and terminating zero fit. */
 const size_t xStringLength = strlen( pcStringToSend ) + 15;

 	/* Remove compiler warning about unused parameters. */
 	( void ) pvParameters;

 	/* It is assumed that this task is not created until the network is up,
 	so the IP address can be obtained immediately.  store the IP address being
 	used in ulIPAddress.  This is done so the socket can send to a different
 	port on the same IP address. */
 	FreeRTOS_GetAddressConfiguration( &ulIPAddress, NULL, NULL, NULL );

 	/* This test sends to itself, so data sent from here is received by a server
 	socket on the same IP address.  Setup the freertos_sockaddr structure with
 	this nodes IP address, and the port number being sent to.  The strange
 	casting is to try and remove compiler warnings on 32 bit machines. */
 	xDestinationAddress.sin_addr = ulIPAddress;
 	xDestinationAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
 	xDestinationAddress.sin_port = FreeRTOS_htons( xDestinationAddress.sin_port );

 	for( ;; )
 	{
 		/* Create the socket. */
 		xClientSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
 		configASSERT( xClientSocket != FREERTOS_INVALID_SOCKET );

 		/* The count is used to differentiate between different messages sent to
 		the server, and to break out of the do while loop below. */
 		ulCount = 0UL;

 		do
 		{
 			/* This task is going to send using the zero copy interface.  The
 			data being sent is therefore written directly into a buffer that is
 			passed into, rather than copied into, the FreeRTOS_sendto()
 			function.

 			First obtain a buffer of adequate length from the IP stack into which
 			the string will be written.  Although a max delay is used, the actual
 			delay will be capped to ipconfigMAX_SEND_BLOCK_TIME_TICKS, hence
 			the do while loop is used to ensure a buffer is obtained. */
 			do
 			{
 			} while( ( pucUDPPayloadBuffer = ( uint8_t * ) FreeRTOS_GetUDPPayloadBuffer( xStringLength, portMAX_DELAY ) ) == NULL );

 			/* A buffer was successfully obtained.  Create the string that is
 			sent to the server.  First the string is filled with zeros as this will
 			effectively be the null terminator when the string is received at the other
 			end.  Note that the string is being written directly into the buffer
 			obtained from the IP stack above. */
 			memset( ( void * ) pucUDPPayloadBuffer, 0x00, xStringLength );
 			sprintf( ( char * ) pucUDPPayloadBuffer, "%s%lu\r\n", pcStringToSend, ulCount );

 			/* Pass the buffer into the send function.  ulFlags has the
 			FREERTOS_ZERO_COPY bit set so the IP stack will take control of the
 			buffer rather than copy data out of the buffer. */
 			lReturned = FreeRTOS_sendto( xClientSocket,  				/* The socket being sent to. */
 										( void * ) pucUDPPayloadBuffer, /* A pointer to the the data being sent. */
 										strlen( ( const char * ) pucUDPPayloadBuffer ) + 1, /* The length of the data being sent - including the string's null terminator. */
 										FREERTOS_ZERO_COPY, 			/* ulFlags with the FREERTOS_ZERO_COPY bit set. */
 										&xDestinationAddress, 			/* Where the data is being sent. */
 										sizeof( xDestinationAddress ) );

 			if( lReturned == 0 )
 			{
 				/* The send operation failed, so this task is still responsible
 				for the buffer obtained from the IP stack.  To ensure the buffer
 				is not lost it must either be used again, or, as in this case,
 				returned to the IP stack using FreeRTOS_ReleaseUDPPayloadBuffer().
 				pucUDPPayloadBuffer can be safely re-used after this call. */
 				FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucUDPPayloadBuffer );
 			}
 			else
 			{
 				/* The send was successful so the IP stack is now managing the
 				buffer pointed to by pucUDPPayloadBuffer, and the IP stack will
 				return the buffer once it has been sent.  pucUDPPayloadBuffer can
 				be safely re-used. */
 			}

 			ulCount++;

 		} while( ( lReturned != FREERTOS_SOCKET_ERROR ) && ( ulCount < ulLoopsPerSocket ) );

 		FreeRTOS_closesocket( xClientSocket );

 		/* A short delay to prevent the messages scrolling off the screen too
 		quickly. */
 		vTaskDelay( x150ms );
 	}
 }
 /*-----------------------------------------------------------*/

 static void prvSimpleZeroCopyServerTask( void *pvParameters )
 {
 int32_t lBytes;
 uint8_t *pucUDPPayloadBuffer;
 struct freertos_sockaddr xClient, xBindAddress;
 uint32_t xClientLength = sizeof( xClient ), ulIPAddress;
 Socket_t xListeningSocket;

 	/* Just to prevent compiler warnings. */
 	( void ) pvParameters;

 	/* Attempt to open the socket. */
 	xListeningSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
 	configASSERT( xListeningSocket != FREERTOS_INVALID_SOCKET );

 	/* This test receives data sent from a different port on the same IP address.
 	Obtain the nodes IP address.  Configure the freertos_sockaddr structure with
 	the address being bound to.  The strange casting is to try and remove
 	compiler warnings on 32 bit machines.  Note that this task is only created
 	after the network is up, so the IP address is valid here. */
 	FreeRTOS_GetAddressConfiguration( &ulIPAddress, NULL, NULL, NULL );
 	xBindAddress.sin_addr = ulIPAddress;
 	xBindAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
 	xBindAddress.sin_port = FreeRTOS_htons( xBindAddress.sin_port );

 	/* Bind the socket to the port that the client task will send to. */
 	FreeRTOS_bind( xListeningSocket, &xBindAddress, sizeof( xBindAddress ) );

 	for( ;; )
 	{
 		/* Receive data on the socket.  ulFlags has the zero copy bit set
 		(FREERTOS_ZERO_COPY) indicating to the stack that a reference to the
 		received data should be passed out to this task using the second
 		parameter to the FreeRTOS_recvfrom() call.  When this is done the
 		IP stack is no longer responsible for releasing the buffer, and
 		the task *must* return the buffer to the stack when it is no longer
 		needed.  By default the block time is portMAX_DELAY. */
 		lBytes = FreeRTOS_recvfrom( xListeningSocket, ( void * ) &pucUDPPayloadBuffer, 0, FREERTOS_ZERO_COPY, &xClient, &xClientLength );

 		/* Print the received characters. */
 		if( lBytes > 0 )
 		{
 			/* It is expected to receive one more byte than the string length as
 			the NULL terminator is also transmitted. */
 			configASSERT( lBytes == ( ( BaseType_t ) strlen( ( const char * ) pucUDPPayloadBuffer ) + 1 ) );
 		}

 		if( lBytes >= 0 )
 		{
 			/* The buffer *must* be freed once it is no longer needed. */
 			FreeRTOS_ReleaseUDPPayloadBuffer( pucUDPPayloadBuffer );
 		}
 	}
 }
	/*
	* FreeRTOS Kernel V10.3.0
	* Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy of
	* this software and associated documentation files (the "Software"), to deal in
	* the Software without restriction, including without limitation the rights to
	* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
	* the Software, and to permit persons to whom the Software is furnished to do so,
	* subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in all
	* copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
	* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
	* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
	* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*
	* http://www.FreeRTOS.org
	* http://aws.amazon.com/freertos
	*
	* 1 tab == 4 spaces!
	*/

	/*
	* Creates two transmitting tasks and two receiving tasks. The transmitting
	* tasks send values that are received by the receiving tasks. One set of tasks
	* uses the standard API. The other set of tasks uses the zero copy API.
	*
	* See the following web page for essential demo usage and configuration
	* details:
	* http://www.FreeRTOS.org/FreeRTOS-Plus/FreeRTOS_Plus_TCP/examples_FreeRTOS_simulator.html
	*/

	/* Standard includes. */
	#include <stdint.h>
	#include <stdio.h>

	/* FreeRTOS includes. */
	#include "FreeRTOS.h"
	#include "task.h"

	/* FreeRTOS+TCP includes. */
	#include "FreeRTOS_IP.h"
	#include "FreeRTOS_Sockets.h"

	#define simpTINY_DELAY ( ( TickType_t ) 2 )

	/*
	* Uses a socket to send data without using the zero copy option.
	* prvSimpleServerTask() will receive the data.
	*/
	static void prvSimpleClientTask( void *pvParameters );

	/*
	* Uses a socket to receive the data sent by the prvSimpleClientTask() task.
	* Does not use the zero copy option.
	*/
	static void prvSimpleServerTask( void *pvParameters );

	/*
	* Uses a socket to send data using the zero copy option.
	* prvSimpleZeroCopyServerTask() will receive the data.
	*/
	static void prvSimpleZeroCopyUDPClientTask( void *pvParameters );

	/*
	* Uses a socket to receive the data sent by the prvSimpleZeroCopyUDPClientTask()
	* task. Uses the zero copy option.
	*/
	static void prvSimpleZeroCopyServerTask( void *pvParameters );

	/-----------------------------------------------------------/

	void vStartSimpleUDPClientServerTasks( uint16_t usStackSize, uint32_t ulPort, UBaseType_t uxPriority )
	{
	/* Create the client and server tasks that do not use the zero copy
	interface. */
	xTaskCreate( prvSimpleClientTask, "SimpCpyClnt", usStackSize, ( void * ) ulPort, uxPriority, NULL );
	xTaskCreate( prvSimpleServerTask, "SimpCpySrv", usStackSize, ( void * ) ulPort, uxPriority + 1, NULL );

	/* Create the client and server tasks that do use the zero copy interface. */
	xTaskCreate( prvSimpleZeroCopyUDPClientTask, "SimpZCpyClnt", usStackSize, ( void * ) ( ulPort + 1 ), uxPriority, NULL );
	xTaskCreate( prvSimpleZeroCopyServerTask, "SimpZCpySrv", usStackSize, ( void * ) ( ulPort + 1 ), uxPriority + 1, NULL );
	}
	/-----------------------------------------------------------/

	static void prvSimpleClientTask( void *pvParameters )
	{
	Socket_t xClientSocket;
	struct freertos_sockaddr xDestinationAddress;
	uint8_t cString[ 65 ];
	BaseType_t lReturned;
	uint32_t ulCount = 0UL, ulIPAddress;
	const uint32_t ulLoopsPerSocket = 10UL;
	const TickType_t x150ms = 150UL / portTICK_PERIOD_MS;

	/* Remove compiler warning about unused parameters. */
	( void ) pvParameters;

	/* It is assumed that this task is not created until the network is up,
	so the IP address can be obtained immediately. store the IP address being
	used in ulIPAddress. This is done so the socket can send to a different
	port on the same IP address. */
	FreeRTOS_GetAddressConfiguration( &ulIPAddress, NULL, NULL, NULL );

	/* This test sends to itself, so data sent from here is received by a server
	socket on the same IP address. Setup the freertos_sockaddr structure with
	this nodes IP address, and the port number being sent to. The strange
	casting is to try and remove compiler warnings on 32 bit machines. */
	xDestinationAddress.sin_addr = ulIPAddress;
	xDestinationAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
	xDestinationAddress.sin_port = FreeRTOS_htons( xDestinationAddress.sin_port );

	for( ;; )
	{
	/* Create the socket. */
	xClientSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
	configASSERT( xClientSocket != FREERTOS_INVALID_SOCKET );

	/* The count is used to differentiate between different messages sent to
	the server, and to break out of the do while loop below. */
	ulCount = 0UL;

	do
	{
	/* Create the string that is sent to the server. */
	sprintf( ( char * ) cString, "Server received (not zero copy): Message number %lu\r\n", ulCount );

	/* Send the string to the socket. ulFlags is set to 0, so the zero
	copy option is not selected. That means the data from cString[] is
	copied into a network buffer inside FreeRTOS_sendto(), and cString[]
	can be reused as soon as FreeRTOS_sendto() has returned. */
	lReturned = FreeRTOS_sendto( xClientSocket, ( void * ) cString, strlen( ( const char * ) cString ), 0, &xDestinationAddress, sizeof( xDestinationAddress ) );

	ulCount++;

	} while( ( lReturned != FREERTOS_SOCKET_ERROR ) && ( ulCount < ulLoopsPerSocket ) );

	FreeRTOS_closesocket( xClientSocket );

	/* A short delay to prevent the messages printed by the server task
	scrolling off the screen too quickly, and to prevent reduce the network
	loading. */
	vTaskDelay( x150ms );
	}
	}
	/-----------------------------------------------------------/

	static void prvSimpleServerTask( void *pvParameters )
	{
	int32_t lBytes;
	uint8_t cReceivedString[ 60 ];
	struct freertos_sockaddr xClient, xBindAddress;
	uint32_t xClientLength = sizeof( xClient );
	Socket_t xListeningSocket;

	/* Just to prevent compiler warnings. */
	( void ) pvParameters;

	/* Attempt to open the socket. */
	xListeningSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
	configASSERT( xListeningSocket != FREERTOS_INVALID_SOCKET );

	/* This test receives data sent from a different port on the same IP
	address. Configure the freertos_sockaddr structure with the address being
	bound to. The strange casting is to try and remove compiler warnings on 32
	bit machines. Note that this task is only created after the network is up,
	so the IP address is valid here. */
	xBindAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
	xBindAddress.sin_port = FreeRTOS_htons( xBindAddress.sin_port );

	/* Bind the socket to the port that the client task will send to. */
	FreeRTOS_bind( xListeningSocket, &xBindAddress, sizeof( xBindAddress ) );

	for( ;; )
	{
	/* Zero out the receive array so there is NULL at the end of the string
	when it is printed out. */
	memset( cReceivedString, 0x00, sizeof( cReceivedString ) );

	/* Receive data on the socket. ulFlags is zero, so the zero copy option
	is not set and the received data is copied into the buffer pointed to by
	cReceivedString. By default the block time is portMAX_DELAY.
	xClientLength is not actually used by FreeRTOS_recvfrom(), but is set
	appropriately in case future versions do use it. */
	lBytes = FreeRTOS_recvfrom( xListeningSocket, cReceivedString, sizeof( cReceivedString ), 0, &xClient, &xClientLength );

	/* Error check. */
	configASSERT( lBytes == ( BaseType_t ) strlen( ( const char * ) cReceivedString ) );
	}
	}
	/-----------------------------------------------------------/

	static void prvSimpleZeroCopyUDPClientTask( void *pvParameters )
	{
	Socket_t xClientSocket;
	uint8_t *pucUDPPayloadBuffer;
	struct freertos_sockaddr xDestinationAddress;
	BaseType_t lReturned;
	uint32_t ulCount = 0UL, ulIPAddress;
	const uint32_t ulLoopsPerSocket = 10UL;
	const char *pcStringToSend = "Server received (using zero copy): Message number ";
	const TickType_t x150ms = 150UL / portTICK_PERIOD_MS;
	/* 15 is added to ensure the number, \r\n and terminating zero fit. */
	const size_t xStringLength = strlen( pcStringToSend ) + 15;

	/* Remove compiler warning about unused parameters. */
	( void ) pvParameters;

	/* It is assumed that this task is not created until the network is up,
	so the IP address can be obtained immediately. store the IP address being
	used in ulIPAddress. This is done so the socket can send to a different
	port on the same IP address. */
	FreeRTOS_GetAddressConfiguration( &ulIPAddress, NULL, NULL, NULL );

	/* This test sends to itself, so data sent from here is received by a server
	socket on the same IP address. Setup the freertos_sockaddr structure with
	this nodes IP address, and the port number being sent to. The strange
	casting is to try and remove compiler warnings on 32 bit machines. */
	xDestinationAddress.sin_addr = ulIPAddress;
	xDestinationAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
	xDestinationAddress.sin_port = FreeRTOS_htons( xDestinationAddress.sin_port );

	for( ;; )
	{
	/* Create the socket. */
	xClientSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
	configASSERT( xClientSocket != FREERTOS_INVALID_SOCKET );

	/* The count is used to differentiate between different messages sent to
	the server, and to break out of the do while loop below. */
	ulCount = 0UL;

	do
	{
	/* This task is going to send using the zero copy interface. The
	data being sent is therefore written directly into a buffer that is
	passed into, rather than copied into, the FreeRTOS_sendto()
	function.

	First obtain a buffer of adequate length from the IP stack into which
	the string will be written. Although a max delay is used, the actual
	delay will be capped to ipconfigMAX_SEND_BLOCK_TIME_TICKS, hence
	the do while loop is used to ensure a buffer is obtained. */
	do
	{
	} while( ( pucUDPPayloadBuffer = ( uint8_t * ) FreeRTOS_GetUDPPayloadBuffer( xStringLength, portMAX_DELAY ) ) == NULL );

	/* A buffer was successfully obtained. Create the string that is
	sent to the server. First the string is filled with zeros as this will
	effectively be the null terminator when the string is received at the other
	end. Note that the string is being written directly into the buffer
	obtained from the IP stack above. */
	memset( ( void * ) pucUDPPayloadBuffer, 0x00, xStringLength );
	sprintf( ( char * ) pucUDPPayloadBuffer, "%s%lu\r\n", pcStringToSend, ulCount );

	/* Pass the buffer into the send function. ulFlags has the
	FREERTOS_ZERO_COPY bit set so the IP stack will take control of the
	buffer rather than copy data out of the buffer. */
	lReturned = FreeRTOS_sendto( xClientSocket, /* The socket being sent to. */
	( void * ) pucUDPPayloadBuffer, /* A pointer to the the data being sent. */
	strlen( ( const char * ) pucUDPPayloadBuffer ) + 1, /* The length of the data being sent - including the string's null terminator. */
	FREERTOS_ZERO_COPY, /* ulFlags with the FREERTOS_ZERO_COPY bit set. */
	&xDestinationAddress, /* Where the data is being sent. */
	sizeof( xDestinationAddress ) );

	if( lReturned == 0 )
	{
	/* The send operation failed, so this task is still responsible
	for the buffer obtained from the IP stack. To ensure the buffer
	is not lost it must either be used again, or, as in this case,
	returned to the IP stack using FreeRTOS_ReleaseUDPPayloadBuffer().
	pucUDPPayloadBuffer can be safely re-used after this call. */
	FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucUDPPayloadBuffer );
	}
	else
	{
	/* The send was successful so the IP stack is now managing the
	buffer pointed to by pucUDPPayloadBuffer, and the IP stack will
	return the buffer once it has been sent. pucUDPPayloadBuffer can
	be safely re-used. */
	}

	ulCount++;

	} while( ( lReturned != FREERTOS_SOCKET_ERROR ) && ( ulCount < ulLoopsPerSocket ) );

	FreeRTOS_closesocket( xClientSocket );

	/* A short delay to prevent the messages scrolling off the screen too
	quickly. */
	vTaskDelay( x150ms );
	}
	}
	/-----------------------------------------------------------/

	static void prvSimpleZeroCopyServerTask( void *pvParameters )
	{
	int32_t lBytes;
	uint8_t *pucUDPPayloadBuffer;
	struct freertos_sockaddr xClient, xBindAddress;
	uint32_t xClientLength = sizeof( xClient ), ulIPAddress;
	Socket_t xListeningSocket;

	/* Just to prevent compiler warnings. */
	( void ) pvParameters;

	/* Attempt to open the socket. */
	xListeningSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
	configASSERT( xListeningSocket != FREERTOS_INVALID_SOCKET );

	/* This test receives data sent from a different port on the same IP address.
	Obtain the nodes IP address. Configure the freertos_sockaddr structure with
	the address being bound to. The strange casting is to try and remove
	compiler warnings on 32 bit machines. Note that this task is only created
	after the network is up, so the IP address is valid here. */
	FreeRTOS_GetAddressConfiguration( &ulIPAddress, NULL, NULL, NULL );
	xBindAddress.sin_addr = ulIPAddress;
	xBindAddress.sin_port = ( uint16_t ) ( ( uint32_t ) pvParameters ) & 0xffffUL;
	xBindAddress.sin_port = FreeRTOS_htons( xBindAddress.sin_port );

	/* Bind the socket to the port that the client task will send to. */
	FreeRTOS_bind( xListeningSocket, &xBindAddress, sizeof( xBindAddress ) );

	for( ;; )
	{
	/* Receive data on the socket. ulFlags has the zero copy bit set
	(FREERTOS_ZERO_COPY) indicating to the stack that a reference to the
	received data should be passed out to this task using the second
	parameter to the FreeRTOS_recvfrom() call. When this is done the
	IP stack is no longer responsible for releasing the buffer, and
	the task must return the buffer to the stack when it is no longer
	needed. By default the block time is portMAX_DELAY. */
	lBytes = FreeRTOS_recvfrom( xListeningSocket, ( void * ) &pucUDPPayloadBuffer, 0, FREERTOS_ZERO_COPY, &xClient, &xClientLength );

	/* Print the received characters. */
	if( lBytes > 0 )
	{
	/* It is expected to receive one more byte than the string length as
	the NULL terminator is also transmitted. */
	configASSERT( lBytes == ( ( BaseType_t ) strlen( ( const char * ) pucUDPPayloadBuffer ) + 1 ) );
	}

	if( lBytes >= 0 )
	{
	/* The buffer must be freed once it is no longer needed. */
	FreeRTOS_ReleaseUDPPayloadBuffer( pucUDPPayloadBuffer );
	}
	}
	}