无法在.NET桌面应用程序中检索访问令牌 [英] Failing to retrieve access token in .NET desktop app

问题描述

我正在写一个在Windows电脑上运行的.NET应用程序。它不能通过浏览器访问。问题是，我不能像我一样认证。我目前在C＃.NET中编码，更具体在C＃中。

• 我的表单上有一个web浏览器控件。
  
• 用户通过此Web浏览器控件登录到Facebook。


• 登录后，我开始验证过程。


• 然后我再检索一个代码。

这里出错了。有了这个代码，我想获得访问令牌。
生成的请求URL如下所示： https://graph.facebook.com/oauth/access_token?client_id=____MY_APP_ID______&redirect_uri=http://localhost/&client_secret=_____MY_APP_SECRET_____&code = ____ MY_RETREIVED_CODE _____ 并通过以下代码进行。

请注意，我的重定向网址是 http：// localhost 。这个应该是可以的，对吗？

此外，在我的应用设置中，我有以下信息。

站点URL： http：// localhost /
站点域：localhost

  private String ExchangeCodeForToken（String code，Uri redirectUrl）
 {
 var TokenEndpoint = new Uri（https：// graph .facebook.com / OAuth的/的access_token）; 
 var url = TokenEndpoint +？ + 
client_id =+ _AppID +& + 
redirect_uri =+ redirectUrl +& + 
client_secret =+ _AppSecret +& + 
code =+ code; 
 var request = WebRequest.CreateDefault（new Uri（url））; 
使用（var response = request.GetResponse（））
 {
 using（var responseStream = response.GetResponseStream（））
 {
 using（var responseReader = new StreamReader（responseStream））
 {
 var responseText = responseReader.ReadToEnd（）; 
 var token = responseText.Replace（access_token =，）; 
返回令牌; 
} 
} 
} 
} 
  

我执行这个，我得到这个错误：

错误http://www.imageupload.org/getfile.php?id=50131&a=447f6fcc0ebd4d3f8e8a59a3a6e36ac3&t = 4de0841c& o = 0889D68FDC35508BA2C6F2689FCBAB7C30A8670CC9647EE598701D8BEC13ED278F0989D393& n = autherror.png& i = 1

Webexception未被用户代码
远程服务器返回错误：（400）错误请求。

我认为我可能会出错： p>

• 我的应用设置是否正确？


• 如果我的重定向网址为 http： // localhost ，即使实际上没有在那边听？

最重要的是：

• 如何摆脱这个错误并检索访问令牌？

提前感谢！

解决方案

你得到这个错误，因为你不应该从桌面应用程序调用这个URL：据我所知，你不能使用令牌端点桌面应用验证。此外，您可以直接获取访问令牌（不需要先询问代码）。

在嵌入式网络浏览器中加载以下URL：

  https://www.facebook.com/dialog/oauth？ 
 client_id = YOUR_APP_ID& 
 redirect_uri = https：//www.facebook.com/connect/login_success.html 
  

用户将被要求登录，并将使用URL中的访问令牌重定向到此URL：

  https：/ /www.facebook.com/connect/login_success.html#access_token = ... 
  

所以你有检测重定向并从URL中检索访问令牌。

I'm writing a .NET app that runs on a Windows computer. It is not accessible through the browser. The problem is, I can't authenticate like I should. I'm currently coding in C# .NET, more specific in C#.

• I have a webbrowser control on my form.
• The user logs on to facebook through this webbrowser control.
• After the logon, I start the authentication procedure.
• I then retreive a code.

Here's where it goes wrong. With this code I want to obtain an access token. The generated request URL looks like: https://graph.facebook.com/oauth/access_token?client_id=____MY_APP_ID______&redirect_uri=http://localhost/&client_secret=_____MY_APP_SECRET_____&code=____MY_RETREIVED_CODE_____ and is made through the code below.

Please note that my redirect URL is http://localhost. This should be okay, right?

Also, in my App Settings, I have the following information.

Site URL: http://localhost/ Site Domain: localhost

private String ExchangeCodeForToken(String code, Uri redirectUrl)
{
    var TokenEndpoint = new Uri("https://graph.facebook.com/oauth/access_token");
    var url = TokenEndpoint + "?" +
                      "client_id=" + _AppID + "&" +
                      "redirect_uri=" + redirectUrl + "&" +
                      "client_secret=" + _AppSecret + "&" +
                      "code=" + code;
    var request = WebRequest.CreateDefault(new Uri(url));
    using (var response = request.GetResponse())
    {
        using (var responseStream = response.GetResponseStream())
        {
            using (var responseReader = new StreamReader(responseStream))
            {
                var responseText = responseReader.ReadToEnd();
                var token = responseText.Replace("access_token=", "");
                return token;
            }
        }
     }
}

When I execute this, I get this error:

error http://www.imageupload.org/getfile.php?id=50131&a=447f6fcc0ebd4d3f8e8a59a3a6e36ac3&t=4de0841c&o=0889D68FDC35508BA2C6F2689FCBAB7C30A8670CC9647EE598701D8BEC13ED278F0989D393&n=autherror.png&i=1

Webexception was unhandled by user code The remote server returned an error: (400) Bad Request.

Here's where I think I might be going wrong:

• Are my app settings correct?
• Should my redirect url be http://localhost, even if there isn't actually a service listening there?

Most importantly:

• how do I get rid of this error and retreive the access token?

Thanks in advance!

解决方案

You get this error because you are not supposed to call this URL from a Desktop app : as far as I know, you can not use the token endpoint for Desktop app authentication. Also, you can get the access token directly (no need to ask for a code first). Here is what you have to do.

Load the following URL in your embedded web browser :

https://www.facebook.com/dialog/oauth?
  client_id=YOUR_APP_ID&
  redirect_uri=https://www.facebook.com/connect/login_success.html

The user will be asked to log in and will be redirected to this URL with the access token in the URL :

https://www.facebook.com/connect/login_success.html#access_token=...

So you have to detect the redirect and retrieve the access token from the URL.

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