Nucleo STM32F7上的UDP回显

Question

I try to make an UDP echo serveur on NUCLEO-F746ZG but when i start the client, my board make just one answer.

This is my thread code :

static void udpecho_thread(void *arg)
{
    err_t err, recv_err;

    LWIP_UNUSED_ARG(arg);

    conn = netconn_new(NETCONN_UDP);
    if (conn != NULL)
    {
        err = netconn_bind(conn, '0xc0a8b26f', 8);
        if (err == ERR_OK)
        {
            while (1)
            {
                recv_err = netconn_recv(conn, &buf);

                if (recv_err == ERR_OK)
                {
                    addr = netbuf_fromaddr(buf);
                    port = netbuf_fromport(buf);
                    netconn_connect(conn, addr, port);
                    buf->addr.addr = 0;
                    netconn_send(conn, buf);
                    netbuf_delete(buf);
                }
            }
        }
        else
        {
            netconn_delete(conn);
        }
    }
}

The client side working on the computer:

Hostname 192.168.178.111 resolved as 192.168.178.111

Reply from 192.168.178.111:8, time 46 ms OK
Une connexion existante a dû être fermée par l'hôte distant
Une connexion existante a dû être fermée par l'hôte distant
Une connexion existante a dû être fermée par l'hôte distant
Une connexion existante a dû être fermée par l'hôte distant

Statistics: Received=1, Corupted=0, Lost=0

Answer 1

This is expected.

err = netconn_bind(conn, '0xc0a8b26f', 8); 

is called only at the start of your thread and then inside is while loop which works all the time. For example, only 1 execution is allowed.

You might consider rewriting this function to something similar to this:

static void udpecho_thread(void *arg) {
    err_t err, recv_err;

    LWIP_UNUSED_ARG(arg);
    while (1) { /* Add this loop */
        conn = netconn_new(NETCONN_UDP);
        if (conn != NULL) {
            err = netconn_bind(conn, '0xc0a8b26f', 8);
            if (err == ERR_OK) {
                while (1) {
                    recv_err = netconn_recv(conn, &buf);

                    if (recv_err == ERR_OK) {
                        addr = netbuf_fromaddr(buf);
                        port = netbuf_fromport(buf);
                        netconn_connect(conn, addr, port);
                        buf->addr.addr = 0;
                        netconn_send(conn,buf);
                        netbuf_delete(buf);
                    } else {
                        break; /* Add break to stop inner loop */
                    }
                }
            }
            netconn_delete(conn);
        }
    }
}

You see, it is very easy to format code

Answer 2

The solution for an EchoServeur is :

static void udpecho_thread(void *arg) {
    err_t err, recv_err;

    LWIP_UNUSED_ARG(arg);
    while (1) { /* Add this loop */
        conn = netconn_new(NETCONN_UDP);
        if (conn!= NULL) {
            err = netconn_bind(conn, '0xc0a8b26f', 8);
            if (err == ERR_OK) {
                while (1) {
                    recv_err = netconn_recv(conn, &buf);

                    if (recv_err == ERR_OK) {
                        addr = netbuf_fromaddr(buf);
                        port = netbuf_fromport(buf);
                        netconn_sendto(conn,buf,addr,port);

                        netbuf_delete(buf);
                    }
                }
            } else  {
                netconn_delete(conn);
            }
        }
    }
}