在Windows Phone 8.1上使用Sharepoint REST API时，HttpClient无法通过第二个请求的NTLM进行身份验证 [英] HttpClient fails to authenticate via NTLM on the second request when using the Sharepoint REST API on Windows Phone 8.1

问题描述

抱歉，长标题很抱歉，但是根据我到目前为止的了解，这似乎是最好的总结。

我们目前正在开发一款通用应用程序，需要使用NTLM身份验证通过REST API访问Sharepoint服务器上的某些文档，事实证明这比应该做的要困难得多。尽管我们能够找到所有问题的解决方法（请参阅下文），但我并不真正了解发生了什么以及为什么有必要解决这些问题。
HttpClient 类在电话和PC上的行为似乎有所不同。

我从以下代码开始：

  var凭据=新的NetworkCredential（用户名，密码）; 
 
 var handler = new HttpClientHandler（）
 {
凭据=凭据
}; 
 
 var client = new HttpClient（handler）; 
 
 var response =等待客户端.GetAsync（url）; 
  

在Windows应用程序中此方法正常，但在Windows Phone应用程序中失败。服务器只返回 401未经授权的状态代码。

某些 之前，但似乎还没有解决方案。

第二个线程的答案表明NTLM握手有问题。但是为什么只有第二次呢？
另外，这似乎是 HttpClient 类的问题，因为以下代码在两个平台上均无问题：

  var request3 = WebRequest.CreateHttp（url）; 
 request3.Credentials =凭据； 
 
 var response3 =等待request3.GetResponseAsync（）; 
 
 var request4 = WebRequest.CreateHttp（url）; 
 request4.Credentials =凭据； 
 
 var response4 =等待request4.GetResponseAsync（）; 
  

因此仅出现问题：

Windows Phone上的

• 。 Windows应用程序中的相同代码有效。


• 连接到Sharepoint时。在两个平台上都可以使用通过NTLM身份验证访问另一个站点。


• 使用 HttpClient 时。使用 WebRequest ，它可以工作。

所以我很高兴自己至少找到了某种使它起作用的方法，我真的很想知道这种组合有什么特别之处，以及可以使它起作用的方法是什么？

解决方案

丹尼尔（Daniel）在执行同步时遇到了同样的问题，因为Windows Phone在缓存方面存在很多问题，最终我可以通过添加标题来解决。
另外，我认为使用超时是一个好主意，因为这是一个很漫长的响应，您可以等待很多时间...而另一个有效的工作方式是使用使用，与使用类似。 Dispose（）。现在，我向您展示代码：

  var request3 = WebRequest.CreateHttp（url）; 
 request3.Credentials =凭据； 
 request.ContinueTimeout = 4000; // 4秒
 
 //用于解决缓存问题
 request.Headers [ Cache-Control] = no-cache; 
 request.Headers [ Pragma] = no-cache; 
 
 using（httpWebResponse response3 =（httpWebResponse）await request3.GetResponseAsync（））{
 if（response3.StatusCode == HttpStatusCode.OK）
 {
 //您的代码... 
} 
} 
 
 var request4 = WebRequest.CreateHttp（url）; 
 request4.Credentials =凭据； 
 request.ContinueTimeout = 4000; // 4秒
 
 //用于解决缓存问题
 request.Headers [ Cache-Control] = no-cache; 
 request.Headers [ Pragma] = no-cache; 
 
 using（httpWebResponse response4 =（httpWebResponse）await request4.GetResponseAsync（））{
 if（response4.StatusCode == HttpStatusCode.OK）
 {
 //您的代码... 
} 
} 
  

我等着我的代码可以帮你。谢谢，祝你好运！

Sorry for the long title, but it seems to be the best summary based on what I know so far.

We’re currently working on a Universal App that needs to access some documents on a Sharepoint server via the REST API using NTLM Authentication, which proves to be more difficult than it should be. While we were able to find workarounds for all problems (see below), I don’t really understand what is happening and why they are even necessary. Somehow the HttpClient class seems to behave differently on the phone and on the PC. Here’s what I figured out so far.

I started with this code:

var credentials = new NetworkCredential(userName, password);

var handler = new HttpClientHandler() 
{
    Credentials = credentials
};

var client = new HttpClient(handler);

var response = await client.GetAsync(url);

This works fine in the Windows app, but it fails in the Windows Phone app. The server just returns a 401 Unauthorized status code.

Some research revealed that you need to provide a domain to the NetworkCredential class.

var credentials = new NetworkCredential(userName, password, domain);

This works on both platforms. But why is the domain not required on Windows?

The next problem appears when you try to do multiple requests:

var response1 = await client.GetAsync(url);
var response2 = await client.GetAsync(url);

Again, this works just fine in the Windows app. Both requests return successfully:

And again, it fails on the phone. The first request returns without problems:

Strangely any consecutive requests to the same resource fail, again with status code 401.

This problem has been encountered before, but there doesn’t seem to be a solution yet.

An answer in the second thread suggests that there’s something wrong with the NTLM handshake. But why only the second time? Also, it seems to be a problem of the HttpClient class, because the following code works without problems on both platforms:

var request3 = WebRequest.CreateHttp(url);
request3.Credentials = credentials;

var response3 = await request3.GetResponseAsync();

var request4 = WebRequest.CreateHttp(url);
request4.Credentials = credentials;

var response4 = await request4.GetResponseAsync();

So the problem only appears:

• on Windows Phone. The same code in a Windows App works.
• when connecting to Sharepoint. Accessing another site with NTLM authentication works on both platforms.
• when using HttpClient. Using WebRequest, it works.

So while I'm glad that I at least found some way to make it work, I’d really like to know what’s so special about this combination and what could be done to make it work?

解决方案

Hi Daniel at the same problem when I do my sync, because windows phone had a lot of problems with cache, finallt I could solve with add headers. Also I think so it's good idea that you use the timeout because it's a loooong response you can wait a lot of time... And the other good way to work it's use "using", it's similar that use ".Dispose()". Now I show you the code:

 var request3 = WebRequest.CreateHttp(url);
 request3.Credentials = credentials;
 request.ContinueTimeout = 4000; //4 seconds

 //For solve cache problems
 request.Headers["Cache-Control"] = "no-cache";
 request.Headers["Pragma"] = "no-cache";

 using(httpWebResponse response3 = (httpWebResponse) await request3.GetResponseAsync()){
      if (response3.StatusCode == HttpStatusCode.OK)
      {
          //Your code...
      }
 }

 var request4 = WebRequest.CreateHttp(url);
 request4.Credentials = credentials;
 request.ContinueTimeout = 4000; //4 seconds

 //For solve cache problems
 request.Headers["Cache-Control"] = "no-cache";
 request.Headers["Pragma"] = "no-cache";

 using(httpWebResponse response4 = (httpWebResponse) await request4.GetResponseAsync()){
      if (response4.StatusCode == HttpStatusCode.OK)
      {
          //Your code...
      }
 }

I wait that my code can help you. Thanks and good luck!

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