SSDP Search in Windows Phone 8

Question

I'm new at SSDP/UPNP/Sockets and all that jazz. I'm playing around with it a bit and I just want to see what a generic SSDP search on my network will bring up.

Using this SSDP Sniffer app, I get a lot of results so I'm attempting to recreate this.

I'm using the following code, which I've found various versions of, but all the tweaking I do doesn't appear to bring back any results. I pretty much at a loss here and would appreciate any guidance.

thanks!

private const string SSDP_IP = "239.255.255.250";
private const string SSDP_PORT = "1900";
private const string SSDP_QUERY = "M-SEARCH * HTTP/1.1\r\n" +
                                  "Host: " + SSDP_IP + ":" + SSDP_PORT + "\r\n" +
                                  "Man: ssdp:discover\r\n" +
                                  "ST: ssdp:all\r\n";

DataGramSocket socket;

async public void SsdpQueryAsync()
{
    var remoteIP = new Windows.Networking.HostName(SSDP_IP);
    var reqBuff = Encoding.UTF8.GetBytes(SSDP_QUERY);

    socket = new DatagramSocket();

    socket.MessageReceived += (sender, args) =>
    {
        // This is invoked for each device that responds to the query...
        Task.Run(() =>
            {
                 // do something useful
            });
    };

    await socket.BindEndpointAsync(null, "");

    socket.JoinMulticastGroup(remoteIP);

    using (var stream = await socket.GetOutputStreamAsync(remoteIP, SSDP_PORT))
    {
        await stream.WriteAsync(reqBuff.AsBuffer());
    }

    await Task.Delay(5000);
}

What does "doesn't appear to bring back any results" mean? Do you get an error? and empty buffer returned? something else? — Matt Lacey
no messages are ever received back so socket.MessageReceived is never triggered. — earthling

Jussi Kukkonen Jussi Kukkonen · Accepted Answer · 2013-09-18T11:23:36

I'm not familiar with C# or dotnet APIs, but I can see some details wrong with the M-SEARCH message:

MAN header must be enclosed in double quotes, so MAN: "ssdp:discover"\r\n
MX header is missing (required for multicast)
USER-AGENT header is missing
missing an empty line in the end
Header names are supposedly case insensitive, but I'd use upper case just in case...

See the Device Architecture reference pdf for more details

SSDP Search in Windows Phone 8

1 Answers