[lwip-users] Consecutive calls to sendto() and recvfrom() functions

[pekez]

Hi guys!

I've been trying to implement UDP server application on my custom ZYNQ 
board. I am using lwip141 1.5 with FreeRTOS.

This is a simple UDP server example I am trying to implement:

while ( TRUE )
    {
        for ( i = 0; i < 4; i++)
        {
            printf("waiting for message...\r\n");
            bytes_received = recvfrom(socket_value, buffer, 
MAX_UDP_PACKET_SIZE, 0, (struct sockaddr*) &client_addr, &addr_size);
            printf("message received: %s\n", buffer);
        }

        buffer[0] = 'e';
        for ( i = 0; i < 4; i++)
        {
            temp = buffer[0] + i;
            sendto(socket_value, &temp, 1, 0, (struct sockaddr*) 
&client_addr, addr_size);
        }
    }

Note: before this while loop I have only calls to socket and bind, and 
of course, part of code that sets sockaddr_in struct for server. So, 
it's really simple app.

On the client side, of course, it is vice versa, I have 4 sendto() calls 
and than 4 recvfrom() calls. I have tried these applications on PC (with 
windows sockets), both server and client were run at the same PC, and 
that works in an expected way. However, when I run my server application 
on ZYNQ board it behaves quite randomly. For example, server receives 
only the last message, while the first three are not received/detected.

Can anyone help me with problem, I would be really grateful? If there is 
any other information I need to give, please tell me, I am not sure 
whether I forgot to mention something.

Thank you