[lwip-users] How do I handle the ETHERNET cable unplug/replug on the ser

Hi there,

your help on the following topic is highly appreciated! Thank You for any help!

How can I handle the unplug replug on the server side using LWIP?

SETUP:

currently I try to get a server application on a STM32H7 running using freeRTOS 10.3 and LWIP 2.1.2.

Code skleton is generated using CubeIDE 6.6 and H7 FW 1.10

CODE:

The application consists of the following threads started in this order

1) the MX_LWIP_Init() function generated by CubeIDE (see below for details)

- setting the addresses and call back functions

- starting the Ethernet thread

2) the physLinkTread

- indicating the cable connection by a notification by static void ethernet_link_status_updated(struct netif *netif)

3) the serverThread

calling the following functions in this order

listen_sock = lwip_socket() // listen_sock will be = 0 if successful

BaseType_t xTrueValue = pdTRUE;
setsockopt( listen_sock , SOL_SOCKET, SO_REUSEADDR , ( void * ) &xTrueValue, sizeof( xTrueValue ))

// wait 10 sec for a client request to come in when accept was succsessful

struct timeval xRcvValue;
xRcvValue.tv_sec = 10U;
xRcvValue.tv_usec = 0U;
setsockopt( listen_sock , SOL_SOCKET, SO_RCVTIMEO , ( void * ) &xRcvValue, sizeof( xRcvValue ))

lwip_bind(listen_sock)

lwip_listen(listen_sock)

for(;;)

{

// will wait 10 sec for any connection request

sock_connection = lwip_accept(listen_sock);

// will wait 4 sec for any client request to be handled

        read = lwip_read(sock_connection);

           //
           if (read)
           {
               // do somthing to serve the request ...
           }

           //
            lwip_shutdown(sock_connection, SHUT_RDWR);
           lwip_close(sock_connection);

}

MY PROBLEM:

I 've tested the ETHERNET cable unplug and (re)plug at the server side

- works fine when done while server is in lwip_accept()

when continuing the shown for(;;) loop the next call of lwip_accept(listen_sock) will return 0

- fails when done while server is in lwip_read()

when continuing the shown for(;;) loop the next call of lwip_accept(listen_sock) will return -1

when discontinuing the for loop just after read was executed and calling

lwip_shutdown(sock_connection, SHUT_RDWR);

lwip_close(sock_connection);

lwip_shutdown(listen_sock, SHUT_RDWR);

lwip_closesocket(listen_sock);

the next call of listen_socklwip_socket() will return -1

What am I missing?

ATTACHMENT:

MX_LWIP_Init():

/* Initilialize the LwIP stack with RTOS */

tcpip_init( NULL, NULL );

/* IP addresses initialization without DHCP (IPv4) */
IP4_ADDR(&ipaddr, IP_ADDRESS[0], IP_ADDRESS[1], IP_ADDRESS[2], IP_ADDRESS[3]);
IP4_ADDR(&netmask, NETMASK_ADDRESS[0], NETMASK_ADDRESS[1] , NETMASK_ADDRESS[2], NETMASK_ADDRESS[3]);
IP4_ADDR(&gw, GATEWAY_ADDRESS[0], GATEWAY_ADDRESS[1], GATEWAY_ADDRESS[2], GATEWAY_ADDRESS[3]);

/* add the network interface (IPv4/IPv6) with RTOS */
netif_add(&gnetif, &ipaddr, &netmask, &gw, NULL, &ethernetif_init, &tcpip_input);

/* Registers the default network interface */
netif_set_default(&gnetif);

if (netif_is_link_up(&gnetif))
{
    /* When the netif is fully configured this function must be called */
    netif_set_up(&gnetif);
}
else
{
    /* When the netif link is down this function must be called */
    netif_set_down(&gnetif);
}

/* Set the link callback function, this function is called on change of link status*/
netif_set_link_callback(&gnetif, ethernet_link_status_updated);

Christian Hensel
Project Engineer Software Development

PHONE +49 351 2637616
EMAIL Hensel.Christian@vonardenne.biz

From:	Hensel, Christian
Subject:	[lwip-users] How do I handle the ETHERNET cable unplug/replug on the server side using LWIP in a correct way?
Date:	Mon, 29 Aug 2022 16:16:06 +0000