Bug 6405 - HttpWebRequest sends duplicate cookies
Summary: HttpWebRequest sends duplicate cookies
Alias: None
Product: Class Libraries
Classification: Mono
Component: System ()
Version: master
Hardware: PC Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2012-08-06 00:45 UTC by Martin Potter
Modified: 2012-08-15 16:29 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Martin Potter 2012-08-06 00:45:11 UTC
We currently use some WCF endpoints that were failing when upgrading to Mono 2.11.2. It appears that the cookies in the supplied CookieContainer are being duplicated, causing the cookie-based authentication to fail. In testing, it appears there is a difference in the way Mono and Microsoft handle cookie headers when a CookieContainer is specified. To demonstrate the issue, run compile the following program and examine the cookie header sent.

using System;
using System.Net;

namespace WebRequestCookies
	class WebRequestCookies
		static void Main(string[] args)
			CookieContainer container = new CookieContainer();
			container.Add(new Uri("http://www.mono-project.com"), new Cookie("foo", "bar"));
			HttpWebRequest request = (HttpWebRequest) WebRequest.Create("http://www.mono-project.com/Main_Page");
			request.CookieContainer = container;
			WebHeaderCollection headers = request.Headers;
			headers.Add("Cookie", "foo=baz");
			HttpWebResponse response = (HttpWebResponse)request.GetResponse();

Only foo=bar should be sent as the cookie header; Mono currently sends foo=baz,foo=bar. On Microsoft's implementation, it appears that when a CookieContainer is set, it becomes the authoritative source for cookie information and only the cookies present in the CookieContainer are sent.
Comment 1 Martin Potter 2012-08-06 00:50:05 UTC
Submitted pull request with fix, https://github.com/mono/mono/pull/420
Comment 2 Martin Potter 2012-08-06 15:03:03 UTC
Added tests for the expected behavior.
Comment 3 Miguel de Icaza [MSFT] 2012-08-15 16:29:36 UTC
Patch applied