Using a proxy with .NET 4.5 HttpClient

Question

I'm troubleshooting a bug with a service I call through .NET's HttpClient, trying to route the request through a local proxy (Fiddler), but my proxy settings seem to not be taking effect.

Here's how I create the client:

private HttpClient CreateHttpClient(CommandContext ctx, string sid) {     var cookies = new CookieContainer();      var handler = new HttpClientHandler {         CookieContainer = cookies,         UseCookies = true,         UseDefaultCredentials = false,         Proxy = new WebProxy("http://localhost:8888", false, new string[]{}),         UseProxy = true,     };      // snip out some irrelevant setting of authentication cookies      var client = new HttpClient(handler) {         BaseAddress = _prefServerBaseUrl,     };      client.DefaultRequestHeaders.Accept.Add(         new MediaTypeWithQualityHeaderValue("application/json"));      return client; } 

then I send the request by:

var response = CreateHttpClient(ctx, sid).PostAsJsonAsync("api/prefs/", smp).Result; 

Request goes straight to the server without attempting to hit the proxy. What did I miss?

Answer 1

This code worked for me:

var httpClientHandler = new HttpClientHandler                         {                             Proxy = new WebProxy("http://localhost:8888", false),                             UseProxy = true                         } 

Note that I am not supplying an empty array to my WebProxy constructor. Perhaps that's the problem?

Answer 2

Ah, The BaseAddress I was pointing to was http://localhost:8081. Turns out that despite setting BypassOnLocal to false, evidently localhost is still special enough that it bypasses the proxy.

I added a domain binding in IIS, host file entry to point that domain to 127.0.0.1, used newly created domain, now it works.