Specifying an originator IP Address on a WebService Request using ServicePoint and HttpWebRequest

If you're running multiple IP Addresses on the same NIC in Windows 2003 server and you need a webservice call to originate from a certain one, you'll probably have found the same thing I did. .net uses the default machine IP address.

I read some posts about specifying only the IP Address you wanted the request to originate from in IIS 6.0 but that didn't help me at all.. I guess this was because mine were on the same NIC.

It took me a while to come up with this solution and I lept for joy when it worked, and made Paul Marshall jump out of his skin.

Create a wrapper for your the Web Service you want to call

The following code shows my wrapped request to a What's My Ip service:

public class SoapServicePointIPWrapper : com.xignite.preview.XigniteHelp
{
    private string servicePointIP;
    public string ServicePointIP
    {
        get { return servicePointIP; }
        set { servicePointIP = value; }
    }
    
    protected override WebRequest GetWebRequest(Uri uri)
    {
        HttpWebRequest request = (HttpWebRequest)base.GetWebRequest(uri);
        request.ServicePoint.BindIPEndPointDelegate = 
                                new System.Net.BindIPEndPoint(BindIPEndPointCallback);
        return request;
    }

    public delegate IPEndPoint BindIPEndPoint(ServicePoint servicePoint, 
                                              IPEndPoint remoteEndPoint, int retryCount);

    private IPEndPoint BindIPEndPointCallback(ServicePoint servicePoint, 
                                              IPEndPoint remoteEndPoint, int retryCount)
    {
        if (retryCount < 3)
            return new IPEndPoint(IPAddress.Parse(servicePointIP), 0);
        else
            return new IPEndPoint(IPAddress.Any, 0);
    }
}

I'd really like to create a Generic wrapper that didn't need to inherit the 2rd party service.. Perhaps using Generics??

Implementation

You can see below, I'm specifying the IP address I want the request to originate from. If the IP address does not exist, it will use the machine default.

SoapServicePointIPWrapper theService = new SoapServicePointIPWrapper();
theService.ServicePointIP = "192.168.1.5"; //your IP
com.xignite.preview.RequestInformation resp = theService.WhatsMyIP();

XMLSerializer<com.xignite.preview.RequestInformation> ser = 
            new XMLSerializer<com.xignite.preview.RequestInformation>();

I hope you found this article in time