每个请求的C#WebClient NTLM身份验证启动

Question

考虑一个简单的C#.NET Framework 4.0应用程序,它:

• 使用WebClient
• 使用NTLM进行身份验证(在IIS 6.0和IIS 7.5服务器上测试)
• 使用DownloadString()多次从URL检索字符串

这是一个工作正常的样本:

using System;
using System.Net;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string URL_status = "http://localhost/status";

            CredentialCache myCache = new CredentialCache();
            myCache.Add(new Uri(URL_status), "NTLM", new NetworkCredential("username", "password", "domain"));

            WebClient WebClient = new WebClient();
            WebClient.Credentials = myCache;

            for (int i = 1; i <= 5; i++)
            {
                string Result = WebClient.DownloadString(new Uri(URL_status));
                Console.WriteLine("Try " + i.ToString() + ": " + Result);
            }

            Console.Write("Done");
            Console.ReadKey();
        }
    }
}

问题:

启用跟踪时,我发现NTLM身份验证不会持久存在.

每次调用Webclient.DownloadString时,NTLM身份验证都会启动(服务器返回"WWW-Authenticate:NTLM"标头,并且整个身份验证/授权过程重复;没有"Connection:close"标头).

是不是NTLM应该验证连接,而不是请求？

有没有办法让WebClient重用现有连接以避免重新验证每个请求？

Answer 1

经过10天尝试我能想到的一切并在此过程中学到很多东西,我终于找到了解决这个问题的方法.

关键是要能够UnsafeAuthenticatedConnectionSharing通过重写GetWebRequest和属性设置为true在HttpWebRequest你回来.

您可能希望将其与ConnectionGroupName属性组合以避免未经身份验证的应用程序对连接的潜在使用.

以下是修改后的问题样本按预期工作.它打开一个NTLM身份验证连接并重用它:

using System;
using System.Net;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string URL_status = "http://localhost/status";

            CredentialCache myCache = new CredentialCache();
            myCache.Add(new Uri(URL_status), "NTLM", new NetworkCredential("username", "password", "domain"));

            MyWebClient webClient = new MyWebClient();
            webClient.Credentials = myCache;

            for (int i = 1; i <= 5; i++)
            {
                string result = webClient.DownloadString(new Uri(URL_status));
                Console.WriteLine("Try {0}: {1}", i, result);
            }

            Console.Write("Done");
            Console.ReadKey();
        }
    }

    public class MyWebClient : WebClient
    {
        protected override WebRequest GetWebRequest(Uri address)
        {
            WebRequest request = base.GetWebRequest(address);

            if (request is HttpWebRequest) 
            {
                var myWebRequest = request as HttpWebRequest;
                myWebRequest.UnsafeAuthenticatedConnectionSharing = true;
                myWebRequest.KeepAlive = true;
            }

            return request;
        }
    }   
}

在这一点上,我还要感谢@Falco Alexander的所有帮助; 虽然他的建议对我不起作用,但他确实指出了我正确的方向寻找并最终找到答案.