CookieContainer bug?

I'm confused how CookieContainer handles domain, so I create this test. This test shows cookieContainer doesn't return any cookie for "example.com" but according to RFC it should return at least 2 cookies.

Isn't it a bug?

How make it to work?

Here is a discussion about this bug:

http://social.msdn.microsoft.com/Forums/en-US/ncl/thread/c4edc965-2dc2-4724-8f08-68815cf1dce6

<%@ Page Language="C#" %>

<%@ Import Namespace="System.Net" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    CookieContainer getContainer()
    {
        CookieContainer result = new CookieContainer();

        Uri uri = new Uri("http://sub.example.com");
        string cookieH = @"Test1=val; domain=sub.example.com; path=/";
        result.SetCookies(uri, cookieH);

        cookieH = @"Test2=val; domain=.example.com; path=/";
        result.SetCookies(uri, cookieH);

        cookieH = @"Test3=val; domain=example.com; path=/";
        result.SetCookies(uri, cookieH);

        return result;
    }

    void Test()
    {
        CookieContainer cookie = getContainer();
        lblResult.Text += "<br>Total cookies count: " + cookie.Count + " &nbsp;&nbsp; expected: 3";

        Uri uri = new Uri("http://sub.example.com");
        CookieCollection coll = cookie.GetCookies(uri);
        lblResult.Text += "<br>For " + uri + " Cookie count: " + coll.Count + " &nbsp;&nbsp; expected: 2";

        uri = new Uri("http://other.example.com");
        coll = cookie.GetCookies(uri);
        lblResult.Text += "<br>For " + uri + " Cookie count: " + coll.Count + " &nbsp;&nbsp; expected: 2";

        uri = new Uri("http://example.com");
        coll = cookie.GetCookies(uri);
        lblResult.Text += "<br>For " + uri + " Cookie count: " + coll.Count + " &nbsp;&nbsp; expected: 2";

    }

    protected void Page_Load(object sender, EventArgs e)
    {
        Test();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>CookieContainer Test Page</title>
</head>
<body>
    <form id="frmTest" runat="server">
    <asp:Label ID="lblResult" EnableViewState="false" runat="server"></asp:Label>
    </form>
</body>
</html>

Solution

I just found the fix for this bug and discussed here: http://dot-net-expertise.blogspot.com/2009/10/cookiecontainer-domain-handling-bug-fix.html

Here is the solution:

Don't use .Add(Cookie), Use only .Add(Uri, Cookie) method.

Call BugFix_CookieDomain each time you add a cookie to the container or before you use .GetCookie or before system use the container.

private void BugFix_CookieDomain(CookieContainer cookieContainer)
{
    System.Type _ContainerType = typeof(CookieContainer);
    Hashtable table = (Hashtable)_ContainerType.InvokeMember("m_domainTable",
                               System.Reflection.BindingFlags.NonPublic |
                               System.Reflection.BindingFlags.GetField |
                               System.Reflection.BindingFlags.Instance,
                               null,
                               cookieContainer,
                               new object[] { });
    ArrayList keys = new ArrayList(table.Keys);
    foreach (string keyObj in keys)
    {
        string key = (keyObj as string);
        if (key[0] == '.')
        {
            string newKey = key.Remove(0, 1);
            table[newKey] = table[keyObj];
        }
    }
}