Salar Salar - 2 months ago 33
C# Question

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>

Answer

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:

  1. Don't use .Add(Cookie), Use only .Add(Uri, Cookie) method.
  2. 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];
            }
        }
    }