Hi all,

I've just spent the afternoon playing around with Donatien's new network framework, specifically playing directly with the socket API.  I've got the TCP side up and running okay doing what I expected it to, but for some reason I don't seem to be able to get anything happening on UDP.

The relevant bits of the code are:

EchoServer::EchoServer() {
    UDPSocket* udpSock;
    udpSock = new UDPSocket;
    udpSock->setOnEvent(this, &EchoServer::onNetUdpSocketEvent);
}

void EchoServer::bind(int tcpPort, int udpPort) {
    udpSock->bind(Host(IP_ADDR_ANY, udpPort));
}

// This method never gets called
void EchoServer::onNetUdpSocketEvent(UDPSocketEvent e) {
    // We're only interested in the READABLE event (it's the only one)
    if ( e == UDPSOCKET_READABLE ) {
        // No need for a handler for UDP - set up a buffer and check client
        char buff[128];
        Host client;
        IpAddr clientIp = client.getIp();
        printf("Incoming UDP connection from %d.%d.%d.%d\r\n", clientIp[0], clientIp[1], clientIp[2], clientIp[3]);
        // Keep reading while there's data to be read
        while ( int len = udpSock->recvfrom(buff, 128, &client) ) {
            if ( len > 0 )
                // If there's data, send it straight back out
                udpSock->sendto(buff, len, &client);
        }
    }
}

The full program is available at http://mbed.org/users/darran/programs/EchoServer

Is there something obvious I'm doing wrong?  Admittedly it could be down to me not even sending UDP packets to the mbed correctly.  I've tried both PCATTCP (http://www.pcausa.com/Utilities/pcattcp.htm) and a small Java program I found and modified to point to my mbed's IP address (http://www.java2s.com/Tutorial/Java/0320__Network/UDPEchoClient.htm).  Neither of which appear to be eliciting any UDP events at all.

Any pointers gratefully appreciated.

I used TCL to craft a quick script sending/receiving some data using UDP or TCP sockets.

To first verify that TCL code works, I did server and client parts and tested it on local PC. Then substituted TCL server with MBED and connecting and sending data was a breeze.

For UDP I used udp1.0.8 package from the 'net (search "TCL udp1.0.8" - first sourceforge link). TCP sockets are supported in TCL out of the box (I used ActiveTCL). If you're interested, I can post the code here.

Hi,

There was actually a bug in the UDP sockets implementation. This was oddly working fine with the NTP Client, but since the program here is acting as a server(although the client/server distinction doesn't make much sense with UDP) this bug is revealing itself...

With the new version I published today your program should be working fine, however there's a small bug in your program as well since you use the client's address before setting it at some point; it should look like:

void EchoServer::onNetUdpSocketEvent(UDPSocketEvent e) {
    // We're only interested in the READABLE event (it's the only one)
    if ( e == UDPSOCKET_READABLE ) {
        // No need for a handler for UDP - set up a buffer and check client
        char buff[128];
        Host client;
        // Keep reading while there's data to be read
        while ( int len = udpSock->recvfrom(buff, 128, &client) ) {
            if ( len > 0 )
                // If there's data, send it straight back out
                udpSock->sendto(buff, len, &client);
        }
        IpAddr clientIp = client.getIp();
        printf("Incoming UDP connection from %d.%d.%d.%d\r\n", clientIp[0], clientIp[1], clientIp[2], clientIp[3]);        
    }
}

For my tests, I've been using Python in command-line mode, the sockets API from the standard library is pretty straightforward.

Cheers,

Donatien

Thanks very much for that, Donatien.  Glad to know I wasn't going entirely mad. :)

Without wanting to start a religious war, my test clients are in Ruby rather than Python or TCL... :)