[lwip-users] Socket blocket in read() until disconnection if first received data is lower than 11 bytes

[sarp]

Dear all,

I've created a TCP server using BSD sockets and NUCLEO-H743ZI2 dev kit with
STM32CubeMX & LwIP 2.0.3

I noticed that:
 if a client connects and sends 11 bytes or more at first, server receives
the data correctly; however, 
 if the data is lower than 11 bytes, read() function blocks until client
disconnects.
Namely, if incoming data is lower than 11 bytes, event_callback is not
triggered until disconnection.

I've pasted my server task below and uploaded the project to the post(Keil -
STM32CubeMX 5.6.0). 
Let me have your kind response at your earliest convenience and feel free to
request related files/flibraries.

Kind Regards
Sarp

void StartTask01(void const * argument)
{
        /* USER CODE BEGIN StartTask01 */
        MX_LWIP_Init();

        /*start a listening tcp server*/
        int iServerSocket;
        struct sockaddr_in address;

        if ((iServerSocket = socket(AF_INET, SOCK_STREAM, 0)) < 0) 
        {
                printf("Socket could not be created\n");
        }
        else
        {
                address.sin_family = AF_INET;
                address.sin_port = htons(80);
                address.sin_addr.s_addr = INADDR_ANY;

                if (bind(iServerSocket, (struct sockaddr *)&address, sizeof 
(address)) <
0)
                {
                        printf("socket could not be bound\n");
                }
                else
                {
                        listen(iServerSocket, MEMP_NUM_NETCONN);        
                }
        }
        /*server started listening*/

        for(;;)
        {
                struct sockaddr_in remoteHost;

                /*block until accepting an incoming connection*/
                int newconn = accept(iServerSocket, (struct sockaddr 
*)&remoteHost,
(socklen_t *)(sizeof(remoteHost)));

                if (newconn != -1)/*if accepted well*/
                {       
                        /*block until data arrives*/
                        read(newconn, xTcpConnParams.caRecBuf, 
sizeof(xTcpConnParams.caRecBuf));
                        printf("data read: %s\n", xTcpConnParams.caRecBuf);
                        memset(xTcpConnParams.caRecBuf, 0, 
sizeof(xTcpConnParams.caRecBuf));
                }
        }
/* USER CODE END StartTask01 */
}



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