HTTPClient在成功之前获得两个401s（发送错误的令牌） [英] HTTPClient getting two 401s before success (sending wrong token)

问题描述

我正在尝试使用 HttpClient 与自托管的WebAPI客户端进行通信。使用以下代码创建客户端：

I'm trying to communicate with a self-hosted WebAPI client using HttpClient. The client is created with the following code:

HttpClientHandler clientHandler = new HttpClientHandler()
{
    UseDefaultCredentials = true,
    PreAuthenticate = true
};
var client = new HttpClient(clientHandler);

：

HttpListener listener = (HttpListener)app.Properties[typeof(HttpListener).FullName];
listener.AuthenticationSchemes = AuthenticationSchemes.IntegratedWindowsAuthentication;

Startup 文件中的

。

in the Startup file.

问题是我在处理请求之前得到两个（或一个预先认证后的一个）401错误。

The problem is that I get two (or one after preauthentication) 401 errors before the request is processed.

在fiddler中，序列如下所示：

In fiddler the sequence looks like this:

First request:
Authorization: Negotiate TlRMTVNTUAABAAAAl7II4gcABwAxAAAACQAJACgAAAAGAbEdAAAAD1dTMTEzLTEyMFNXVC0xMTM=
Answer:
WWW-Authenticate: Negotiate TlRMTVNTUAACAAAADgAOADgAAAAVwonisrQOBMTKHhKwCkgCAAAAAJoAmgBGAAAABgGxHQAAAA9TAFcAVAAtADEAMQAzAAIADgBTAFcAVAAtADEAMQAzAAEAEgBXAFMAMQAxADMALQAxADIAMAAEABYAcwB3AHQALQAxADEAMwAuAGwAbwBjAAMAKgBXAFMAMQAxADMALQAxADIAMAAuAHMAdwB0AC0AMQAxADMALgBsAG8AYwAFABYAQQBMAEQASQA5ADkAOQAuAGwAbwBjAAcACACkGh0XVY3QAQAAAAA=

Second request (succeeds):
Authorization: Negotiate TlRMTVNTUAADAAAAAAAAAFgAAAAAAAAAWAAAAAAAAABYAAAAAAAAAFgAAAAAAAAAWAAAAAAAAABYAAAAFcKI4gYBsR0AAAAPfJafWSuLL0sAXYtWCynOqg==

那么为什么我的客户不是第一次发送正确的授权令牌但总是需要这两个时间方法？

So why isn't my client sending the correct authorization token the first time around but always needs this two-time approach?

推荐答案

您遇到的情况很正常，这就是NTLM身份验证方案的工作原理。

What you are experiencing is normal, this is how the NTLM authentication scheme works.

1: C  --> S   GET ...

2: C <--  S   401 Unauthorized
              WWW-Authenticate: NTLM

3: C  --> S   GET ...
              Authorization: NTLM <base64-encoded type-1-message>

4: C <--  S   401 Unauthorized
              WWW-Authenticate: NTLM <base64-encoded type-2-message>

5: C  --> S   GET ...
              Authorization: NTLM <base64-encoded type-3-message>

6: C <--  S   200 Ok

1. 客户端向服务器发送 GET 请求。


2. 由于您需要通过身份验证才能访问所请求的资源，服务器发送回 401 Unathorized 响应，并在 WWW-Authenticate 标头中通知客户端它支持 NTLM 身份验证。因此，您可以在这里获得第一个 401 响应代码。


3. 客户端将域名和用户名发送到服务器中授权标头。请注意，仅基于这些信息，客户端无法进行身份验证。


4. 服务器向客户端发送质询。它是一个随机生成的数字，称为 nonce 。这是您获得第二个 401 响应代码的地方。


5. 客户端使用密码的哈希值向服务器的挑战发回响应加密随机数。


6. 服务器将客户端的用户名，发送给客户端的质询和从客户端收到的响应发送到域控制器。使用用户名，域控制器检索用户密码的哈希值并使用它加密质询。如果结果与客户端发送的响应匹配，则客户端将通过身份验证，服务器将 200 响应代码和请求的资源发送回客户端。

1. The client sends a GET request to the server.
2. Since you need to be authenticated to access the requested resource, the server sends back a 401 Unathorized response and notifies the client in the WWW-Authenticate header that it supports NTLM authentication. So this is where you get your first 401 response code.
3. The client sends the domain name and the username to the server in the Authorization header. Note that based solely on these information the client cannot be authenticated yet.
4. The server sends a challenge to the client. It's a randomly generated number called a nonce. This is where you get your second 401 response code.
5. The client sends back a response to the server's challenge, using its password's hash to encrypt the random number.
6. The server sends the client's username, the challenge sent to the client and the response received from the client to the domain controller. Using the username the domain controller retrieves the hash of the user's password and encrypts the challenge with it. If the result matches the response sent by the client, the client is authenticated and the server sends back a 200 response code and the requested resource to the client.

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