c# Winforms WebBrowser - Clear all cookies

Hello,

I recently search for a method to delete all cookies from the build in .NET WinForms WebBrowser control.

I didn't found any working solution for it, nor working example.

It being told to use InternetSetOption, but nothing found about it.

So, i will write here my solution for clearing and deleting all cookies.

My solution using InternetSetOption with the option flag: INTERNET_OPTION_SUPPRESS_BEHAVIOR, which described as:

A general purpose option that is used to suppress behaviors on a process-wide basis. The lpBuffer parameter of the function must be a pointer to a DWORD containing the specific behavior to suppress. This option cannot be queried with InternetQueryOption.

This option flag should be used together with INTERNET_SUPPRESS_COOKIE_PERSIST options, which means:

Suppresses the persistence of cookies, even if the server has specified them as persistent.

So the example code for it will be:

static void Main()
{
    SuppressWininetBehavior();

    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    Application.Run(new Form1());
}

[System.Runtime.InteropServices.DllImport("wininet.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto, SetLastError = true)]
public static extern bool InternetSetOption(int hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength);

private static unsafe void SuppressWininetBehavior()
{
    /* SOURCE: http://msdn.microsoft.com/en-us/library/windows/desktop/aa385328%28v=vs.85%29.aspx
        * INTERNET_OPTION_SUPPRESS_BEHAVIOR (81):
        *      A general purpose option that is used to suppress behaviors on a process-wide basis. 
        *      The lpBuffer parameter of the function must be a pointer to a DWORD containing the specific behavior to suppress. 
        *      This option cannot be queried with InternetQueryOption. 
        *      
        * INTERNET_SUPPRESS_COOKIE_PERSIST (3):
        *      Suppresses the persistence of cookies, even if the server has specified them as persistent.
        *      Version:  Requires Internet Explorer 8.0 or later.
        */

    int option = (int)3/* INTERNET_SUPPRESS_COOKIE_PERSIST*/;
    int* optionPtr = &option;

    bool success = InternetSetOption(0, 81/*INTERNET_OPTION_SUPPRESS_BEHAVIOR*/, new IntPtr(optionPtr), sizeof(int));
    if (!success)
    {
        MessageBox.Show("Something went wrong !>?");
    }
}

Please make sure your project is allows unsafe code. (under Properties => Build Tab)

This code is deleting the COOKIES per PROCESS on startup ONLY.
[tested on WIN-7 and working great]


Best Regards,
MDB-BLOG :)