Get content of response with StatusCode 401

I'm trying to establish a connection to a server that sends 401 Authentication Error for all my requests along with the normal html response. e.g. However, I also want to read the HTML response that is sent alongwith so that I can parse that. An example header exchange captured using LiveHTTPHeaders: Clearly, content-length is non-zero. Firefox shows it to be javascript.

https://172.31.1.251:1003/fgtauth?73e285357b2dc5cc
Request:
GET /fgtauth?73e285357b2dc5cc HTTP/1.1
Host: 172.31.1.251:1003
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1b4) Gecko/20090423 Firefox/3.5b4 (.NET CLR 3.5.30729)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive

Response:
HTTP/1.x 401 Unauthorized
WWW-Authenticate: Fortigate
Content-Length: 1091
Connection: Keep-Alive
Cache-Control: no-cache
Content-Type: text/html

At this point, a form opens in firefox that asks me to enter my username and password.

https://172.31.1.251:1003/

Request:
POST / HTTP/1.1
Host: 172.31.1.251:1003
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1b4) Gecko/20090423 Firefox/3.5b4 (.NET CLR 3.5.30729)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: https://172.31.1.251:1003/
Content-Type: application/x-www-form-urlencoded
Content-Length: 93
magic=73e285开发者_开发百科357b2dc5cc&username=uuxx&password=xxuu&4Tredir=http%3A%2F%2Fwww.google.com%2F


Response:
HTTP/1.x 401 Unauthorized
WWW-Authenticate: Fortigate
Content-Length: 924
Connection: Keep-Alive
Cache-Control: no-cache
Content-Type: text/html

At this point I am redirected to another URL. However, the problem that I have is how to get the content of lenght 924 that is sent along with the 401 Unauthorized, because that content will help me in doing what I want to do further. But the very line:

WebResponse loginResponse = loginRequest.GetResponse();

throws an exception.

I will be grateful for any suggestions to help me get to the actual content.

Thanks.

You need to read the WebException's Response property, like this:

WebResponse loginResponse;
try {
    loginResponse = loginRequest.GetResponse();
} catch(WebException ex) {
    if (ex.Status == WebExceptionStatus.ProtocolError) {
        loginResponse = ex.Response;
    } else
        throw;
}

//Do something with the response, and remember to dispose it.