I have a server with multi ip addresses. Now I need to communicate with several servers with http protocol. Each server only accept the request from a specified ip address of my server. But when using WebRequest(or HttpWebRequest) in .NET , the request object will choose a ip address automatically. I can't find anyway to bind the request with a address.
Is there anyway to do so ? Or I have to implement a webrequest class myself ?
You need to use the ServicePoint.BindIPEndPointDelegate callback.
http://blogs.msdn.com/b/malarch/archive/2005/09/13/466664.aspx
The delegate is called before the socket associated with the httpwebrequest attempts to connect to the remote end.
public static IPEndPoint BindIPEndPointCallback(ServicePoint servicePoint, IPEndPoint remoteEndPoint, int retryCount)
{
Console.WriteLine("BindIPEndpoint called");
return new IPEndPoint(IPAddress.Any,5000);
}
public static void Main()
{
HttpWebRequest request = (HttpWebRequest) WebRequest.Create("http://MyServer");
request.ServicePoint.BindIPEndPointDelegate = new BindIPEndPoint(BindIPEndPointCallback);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
}
If you want to do this using WebClient you'll need to subclass it:
var webClient = new WebClient2(IPAddress.Parse("10.0.0.2"));
and the subclass:
public class WebClient2 : WebClient
{
public WebClient2(IPAddress ipAddress) {
_ipAddress = ipAddress;
}
protected override WebRequest GetWebRequest(Uri address)
{
WebRequest request = (WebRequest)base.GetWebRequest(address);
((HttpWebRequest)request).ServicePoint.BindIPEndPointDelegate += (servicePoint, remoteEndPoint, retryCount) => {
return new IPEndPoint(_ipAddress, 0);
};
return request;
}
}
(thanks @Samuel for the all important ServicePoint.BindIPEndPointDelegate part)
