WCF web service discovery on network interfaces with multiple IP addresses

Question

I'm trying to do a webservice discovery using WCF's DiscoveryClient using this code:

// Setup the discovery client (WSDiscovery April 2005)
DiscoveryEndpoint discoveryEndpoint = new UdpDiscoveryEndpoint(DiscoveryVersion.WSDiscoveryApril2005);
DiscoveryClient discoveryClient = new DiscoveryClient(discoveryEndpoint);

// Setup the wanted device criteria
FindCriteria criteria = new FindCriteria();
criteria.ScopeMatchBy = new Uri("http://schemas.xmlsoap.org/ws/2005/04/discovery/rfc3986");
criteria.Scopes.Add(new Uri("onvif://www.onvif.org/"));

// Go find!
criteria.Duration = TimeSpan.FromMilliseconds(duration);
discoveryClient.FindAsync(criteria, this);

This works very well on a machine with a single IP address (10.1.4.25) assigned to the single network interface. The broadcast is sent from 10.1.4.25 to 239.255.255.250, and I get responses from 5 devices all on the same subnet.

However, when the machine has multiple IPs on the same interface, it seems to pick a single source IP and sends the request from that. In this case, I get a reply from a single device giving a 169.254 address.

I have tried setting UdpDiscoveryEndpoint.TransportSettings.MulticastInterfaceId to a suitable interface ID which hasn't helped as it identifies a single interface, not a specific IP. The UdpDiscoveryEndpoint.ListenUri property also returns the multicast address, and so won't effect the source IP. UdpDiscoveryEndpoint.Address is the URN for the discovery protocol.

Is there any way I can force it to send from a specific IP address, or ideally, multiple requests on each configured IP?

I have also tried ONVIF Device Manager that seems to have the same problem.

Note that this is not about making a service bind to a specific, or "all address" IP. It is about the IP a discovery request is sent from.

Answer 1

Well, I had the same problem and after some days of research, reading ONVIF documents and learning some tips about multicasting, I developed this code which works fine. As an example the main IP address on my network adapter is 192.168.80.55 and I also set another IP(192.168.0.10) in advanced settings. With use of this code I can discover device service of a camera with the IP address of 192.168.0.12. The most important part of this sample is "DeepDiscovery" method which contains the main idea of iteration on network addresses and multicasting proper Probe message. I recommend deserialization of the response in "GetSocketResponse" method. Currently, just I extract the service URI using Regex.

As mentioned in this article (https://msdn.microsoft.com/en-us/library/dd456791(v=vs.110).aspx):

For WCF Discovery to work correctly, all NICs (Network Interface Controller) should only have 1 IP address.

I am doing the exact action that WS-Discovery does and using the standard 3702 port, but I myself build the SOAP envelope and use Socket class for sending the packet for all IP addresses that have been set for the network interface controller.

class Program
{
    static readonly List<string> addressList = new List<string>();
    static readonly IPAddress multicastAddress = IPAddress.Parse("239.255.255.250");
    const int multicastPort = 3702;
    const int unicastPort = 0;

    static void Main(string[] args)
    {
        DeepDiscovery();
        Console.ReadKey();
    }

    public static void DeepDiscovery()
    {
        string probeMessageTemplate = @"<s:Envelope xmlns:s=""http://www.w3.org/2003/05/soap-envelope"" xmlns:a=""http://schemas.xmlsoap.org/ws/2004/08/addressing""><s:Header><a:Action s:mustUnderstand=""1"">http://schemas.xmlsoap.org/ws/2005/04/discovery/Probe</a:Action><a:MessageID>urn:uuid:{messageId}</a:MessageID><a:ReplyTo><a:Address>http://schemas.xmlsoap.org/ws/2004/08/addressing/role/anonymous</a:Address></a:ReplyTo><a:To s:mustUnderstand=""1"">urn:schemas-xmlsoap-org:ws:2005:04:discovery</a:To></s:Header><s:Body><Probe xmlns=""http://schemas.xmlsoap.org/ws/2005/04/discovery""><d:Types xmlns:d=""http://schemas.xmlsoap.org/ws/2005/04/discovery"" xmlns:dp0=""http://www.onvif.org/ver10/device/wsdl"">dp0:Device</d:Types></Probe></s:Body></s:Envelope>";

        foreach (IPAddress localIp in
            Dns.GetHostAddresses(Dns.GetHostName()).Where(i => i.AddressFamily == AddressFamily.InterNetwork))
        {
            var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            socket.Bind(new IPEndPoint(localIp, unicastPort));
            socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(multicastAddress, localIp));
            socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, 255);
            socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            socket.MulticastLoopback = true;
            var thread = new Thread(() => GetSocketResponse(socket));
            var probeMessage = probeMessageTemplate.Replace("{messageId}", Guid.NewGuid().ToString());
            var message = Encoding.UTF8.GetBytes(probeMessage);
            socket.SendTo(message, 0, message.Length, SocketFlags.None, new IPEndPoint(multicastAddress, multicastPort));
            thread.Start();
        }
    }


    public static void GetSocketResponse(Socket socket)
    {
        try
        {
            while (true)
            {
                var response = new byte[3000];
                EndPoint ep = socket.LocalEndPoint;
                socket.ReceiveFrom(response, ref ep);
                var str = Encoding.UTF8.GetString(response);
                var matches = Regex.Matches(str, @"http://\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b/onvif/device_service");
                foreach (var match in matches)
                {
                    var value = match.ToString();
                    if (!addressList.Contains(value))
                    {
                        Console.WriteLine(value);
                        addressList.Add(value);
                    }
                }
                //...
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
            //...
        }
    }
}