从 Xamarin 应用程序中的身份服务器获取 OAuth 访问令牌

Question

Within a Xamarin application I have created, I'm trying to connect to a Web API which I'm running locally in a separate solution. In order to successfully connect to this API I have to retrieve an access token from the identity server endpoint (OAuth 2.0).

I'm currently finding it very difficult to find a solution that allows me to retrieve this token.

In existing .NET projects I have used the following code to retrieve the access token but in the Xamarin App this does not work, it hits the first line and comes back 5 minutes later saying it was cancelled:

try
{
   var disco = await httpClient.GetDiscoveryDocumentAsync(new DiscoveryDocumentRequest
   {
       Address = clientCredentials.Path,
       Policy =
       {
          RequireHttps = false
       }
   });

   if (disco.IsError) Console.WriteLine(disco.Error);

   var tokenResponse = await httpClient.RequestClientCredentialsTokenAsync(newClientCredentialsTokenRequest
   {
       Address = "https://<local-machine-ip>:<port-of-auth-localhost>/connect/token",
       ClientId = clientCredentials.ClientId,
       ClientSecret = clientCredentials.ClientSecret,
       Scope = clientCredentials.Scope
   });

   if (tokenResponse.IsError) Console.WriteLine(tokenResponse.Error);

   httpClient.SetBearerToken(tokenResponse.AccessToken);
}
catch (Exception ex)
{
  Console.WriteLine(ex.Message);
}

The closest I have got is through this code, but this returns the 'Error: TrustFailure (Authentication failed, see inner exception.)':

var client = new RestClient("https://<local-machine-ip>:<port-of-auth-localhost>/connect/token");
var request = new RestRequest(Method.POST);

request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddParameter("application/x-www-form-urlencoded", "grant_type=client_credentials&client_id=xxxx&client_secret=xxxxx&scope=xxxxx", ParameterType.RequestBody);

IRestResponse response = await client.ExecuteAsync(request);

I'm running out of ideas at this point, does anyone know of a solution?

Just to note I am running xamarin.android the android emulator. The code shown above currently sits in a class within the ClassLibrary of the xamarin.forms solution

Answer 1

locahost is the emulator itself, not the PC that is hosting the emulator, use 10.0.2.2 instead to "reach" the hosting PC.

Also note that the address 127.0.0.1 on your development machine corresponds to the emulator's own loopback interface. If you want to access services running on your development machine loopback interface (aka 127.0.0.1 on your machine), you should use the special address 10.0.2.2 instead.

Set up Android Emulator networking: https://developer.android.com/studio/run/emulator-networking