webBrowser1.Document.Cookie取不到HttpOnly的Cookie，取Cookie不完整

 在做数据采集时，有些网站需要输入验证码，但各网站验证码都不同，不可能有完美的识别验证码的代码，所以我也没去研究，我所采取的方案是：在winform里通过WebBrowser调用网页先手动登录系统，然后再通过webBrowser1.Document.Cookie获取其Cookie，再将其用到HttpWebRequest里用来访问自己需要的页。

一直用的都没有问题，但最近在对一个网站操作时总是不能获取完整Cookie，百思不得其解，使用Fiddler2对比发现，不能获取到的Cookie里最后有一个HttpOnly的标识，顺藤摸瓜发现原来webBrowser1.Document.Cookie里是取不到HttpOnly的Cookie的，也找到解决方法：

using System;   
using System.ComponentModel;   
using System.Net;   
using System.Runtime.InteropServices;   
using System.Security;   
using System.Security.Permissions;   
using System.Text;   
  
  
internal sealed class NativeMethods   
{  
    #region enums   
  
    public enum ErrorFlags   
    {   
        ERROR_INSUFFICIENT_BUFFER = 122,   
        ERROR_INVALID_PARAMETER = 87,   
        ERROR_NO_MORE_ITEMS = 259   
    }   
  
    public enum InternetFlags   
    {   
        INTERNET_COOKIE_HTTPONLY = 8192, //Requires IE 8 or higher   
        INTERNET_COOKIE_THIRD_PARTY = 131072,   
        INTERNET_FLAG_RESTRICTED_ZONE = 16   
    }  
 
    #endregion  
 
    #region DLL Imports   
  
    [SuppressUnmanagedCodeSecurity, SecurityCritical, DllImport("wininet.dll", EntryPoint = "InternetGetCookieExW", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true)]   
    internal static extern bool InternetGetCookieEx([In] string Url, [In] string cookieName, [Out] StringBuilder cookieData, [In, Out] ref uint pchCookieData, uint flags, IntPtr reserved);  
 
    #endregion   
}   
  
  
/// <SUMMARY></SUMMARY>   
/// 取得WebBrowser的完整Cookie。   
/// 因为默认的webBrowser1.Document.Cookie取不到HttpOnly的Cookie   
///    
public class FullWebBrowserCookie   
{   
  
    [SecurityCritical]   
    public static string GetCookieInternal(Uri uri, bool throwIfNoCookie)   
    {   
        uint pchCookieData = 0;   
        string url = UriToString(uri);   
        uint flag = (uint)NativeMethods.InternetFlags.INTERNET_COOKIE_HTTPONLY;   
  
        //Gets the size of the string builder   
        if (NativeMethods.InternetGetCookieEx(url, null, null, ref pchCookieData, flag, IntPtr.Zero))   
        {   
            pchCookieData++;   
            StringBuilder cookieData = new StringBuilder((int)pchCookieData);   
  
            //Read the cookie   
            if (NativeMethods.InternetGetCookieEx(url, null, cookieData, ref pchCookieData, flag, IntPtr.Zero))   
            {   
                DemandWebPermission(uri);   
                return cookieData.ToString();   
            }   
        }   
  
        int lastErrorCode = Marshal.GetLastWin32Error();   
  
        if (throwIfNoCookie || (lastErrorCode != (int)NativeMethods.ErrorFlags.ERROR_NO_MORE_ITEMS))   
        {   
            throw new Win32Exception(lastErrorCode);   
        }   
  
        return null;   
    }   
  
    private static void DemandWebPermission(Uri uri)   
    {   
        string uriString = UriToString(uri);   
  
        if (uri.IsFile)   
        {   
            string localPath = uri.LocalPath;   
            new FileIOPermission(FileIOPermissionAccess.Read, localPath).Demand();   
        }   
        else  
        {   
            new WebPermission(NetworkAccess.Connect, uriString).Demand();   
        }   
    }   
  
    private static string UriToString(Uri uri)   
    {   
        if (uri == null)   
        {   
            throw new ArgumentNullException("uri");   
        }   
  
        UriComponents components = (uri.IsAbsoluteUri ? UriComponents.AbsoluteUri : UriComponents.SerializationInfoString);   
        return new StringBuilder(uri.GetComponents(components, UriFormat.SafeUnescaped), 2083).ToString();   
    }   
}   

 可能有用的资料：

Retrieve HttpOnly Session Cookie in WebBrowser

C#下利用WebBrowser完整获取COOKIE