创建、配置和绑定 TCP 套接字
FreeRTOS-Plus-TCP 联网教程节选

void vCreateTCPClientSocket( void )

{

Socket_t xClientSocket;

socklen_t xSize = sizeof( freertos_sockaddr );

static const TickType_t xTimeOut = pdMS_TO_TICKS( 2000 );



    /* Attempt to open the socket. */

    xClientSocket = FreeRTOS_socket( FREERTOS_AF_INET4, /* Or FREERTOS_AF_INET6 for IPv6. */

                                     SOCK_STREAM,  /* SOCK_STREAM for TCP. */

                                     IPPROTO_TCP );



    /* Check the socket was created. */

    configASSERT( xClientSocket != FREERTOS_INVALID_SOCKET );



    /* If FREERTOS_SO_RCVBUF or FREERTOS_SO_SNDBUF are to be used with

    FreeRTOS_setsockopt() to change the buffer sizes from their default then do

    it here!.  (see the FreeRTOS_setsockopt() documentation. */



    /* If ipconfigUSE_TCP_WIN is set to 1 and FREERTOS_SO_WIN_PROPERTIES is to

    be used with FreeRTOS_setsockopt() to change the sliding window size from

    its default then do it here! (see the FreeRTOS_setsockopt()

    documentation. */



    /* Set send and receive time outs. */

    FreeRTOS_setsockopt( xClientSocket,

                         0,

                         FREERTOS_SO_RCVTIMEO,

                         &xTimeOut,

                         sizeof( xTimeOut ) );



    FreeRTOS_setsockopt( xClientSocket,

                         0,

                         FREERTOS_SO_SNDTIMEO,

                         &xTimeOut,

                         sizeof( xTimeOut ) );



    /* Bind the socket, but pass in NULL to let FreeRTOS-Plus-TCP choose the port number.

    See the next source code snipped for an example of how to bind to a specific

    port number. */

    FreeRTOS_bind( xClientSocket, NULL, xSize );

}

void vCreateTCPServerSocket( void )

{

struct freertos_sockaddr xClient, xBindAddress;

Socket_t xListeningSocket, xConnectedSocket;

socklen_t xSize = sizeof( xClient );

static const TickType_t xReceiveTimeOut = portMAX_DELAY;

const BaseType_t xBacklog = 20;



    /* Attempt to open the socket. */

    xListeningSocket = FreeRTOS_socket( FREERTOS_AF_INET4, /* Or FREERTOS_AF_INET6 for IPv6. */

                                        SOCK_STREAM,  /* SOCK_STREAM for TCP. */

                                        IPPROTO_TCP );



    /* Check the socket was created. */

    configASSERT( xListeningSocket != FREERTOS_INVALID_SOCKET );



    /* If FREERTOS_SO_RCVBUF or FREERTOS_SO_SNDBUF are to be used with

    FreeRTOS_setsockopt() to change the buffer sizes from their default then do

    it here!.  (see the FreeRTOS_setsockopt() documentation. */



    /* If ipconfigUSE_TCP_WIN is set to 1 and FREERTOS_SO_WIN_PROPERTIES is to

    be used with FreeRTOS_setsockopt() to change the sliding window size from

    its default then do it here! (see the FreeRTOS_setsockopt()

    documentation. */



    /* Set a time out so accept() will just wait for a connection. */

    FreeRTOS_setsockopt( xListeningSocket,

                         0,

                         FREERTOS_SO_RCVTIMEO,

                         &xReceiveTimeOut,

                         sizeof( xReceiveTimeOut ) );



    /* Set the listening port to 10000. */

    xBindAddress.sin_port = ( uint16_t ) 10000;

    xBindAddress.sin_port = FreeRTOS_htons( xBindAddress.sin_port );



    /* Bind the socket to the port that the client RTOS task will send to. */

    FreeRTOS_bind( xListeningSocket, &xBindAddress, sizeof( xBindAddress ) );



    /* Set the socket into a listening state so it can accept connections.

    The maximum number of simultaneous connections is limited to 20. */

    FreeRTOS_listen( xListeningSocket, xBacklog );



    for( ;; )

    {

        /* Wait for incoming connections. */

        xConnectedSocket = FreeRTOS_accept( xListeningSocket, &xClient, &xSize );

        configASSERT( xConnectedSocket != FREERTOS_INVALID_SOCKET );



        /* Spawn a RTOS task to handle the connection. */

        xTaskCreate( prvServerConnectionInstance,

                     "EchoServer",

                     usUsedStackSize,

                     ( void * ) xConnectedSocket,

                     tskIDLE_PRIORITY,

                     NULL );

    }

}