C# – Xamarin.Forms HTTPS and Self Signed Certificate Issue

chttpssslxamarinxamarin.forms

I am using Xamarin.Forms and my priority is UWP. I am trying to make a post request via System.Net.Http.HttpClient and my code looks like this

public async Task<LoginResponse> Login(User user)
{
    HttpClient client = await GetClient();

    var response = await client.PostAsync(Url, new StringContent(JsonConvert.SerializeObject(user), Encoding.UTF8, "application/json"));
    var mobileResult = await response.Content.ReadAsStringAsync();
    var result = JsonConvert.DeserializeObject<LoginResponse>(mobileResult);

    return result;
}

When i make the request i am getting this error

System.Net.Http.HttpRequestException: An error occurred while sending
the request. —> System.Runtime.InteropServices.COMException: The
text associated with this error code could not be found.

The certificate authority is invalid or incorrect

at
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
task) at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task) at
System.Net.Http.HttpHandlerToFilter.d__4.MoveNext()
— End of stack trace from previous location where exception was thrown — at
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
task) at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task) at
System.Net.Http.HttpClientHandler.d__86.MoveNext() —
End of inner exception stack trace — at
System.Net.Http.HttpClientHandler.d__86.MoveNext()
— End of stack trace from previous location where exception was thrown — at
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
task) at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task) at
System.Net.Http.HttpClient.d__58.MoveNext()
— End of stack trace from previous location where exception was thrown — at
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
task) at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task) at System.Runtime.CompilerServices.TaskAwaiter1.GetResult()
at SampleApp.Services.LoginService.<Login>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown --- at
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
task) at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task) at System.Runtime.CompilerServices.TaskAwaiter1.GetResult()
at SampleApp.Views.LoginPage.d__1.MoveNext()

I think the self-signed SSL causing the problem. I know i can use Windows.Web HttpClient to ignore SSL errors but due to some problems it is not possible now.
How can i solve this problem ? Thanks in advance.

Best Answer

This code help for resolve the below error in Xamarin- Windows (UWP) - Windows 8.1

"The text associated with this error code could not be found."

  public interface IServerCommunication
  {
   Task<string> GetFromServerAsync(string URL);
  }

//later on, when I download the data: (URL is a provided string)

  string result = await DependencyService.Get<IServerCommunication> 
  ().GetFromServerAsync(URL);

   public async Task<string> GetFromServerAsync(string URL)
   {
    HttpClient client = await PreparedClientAsync();

    HttpResponseMessage response;

    try
    {
    response = await client.GetAsync(new Uri(URL));

    IBuffer buffer = await response.Content.ReadAsBufferAsync();
    DataReader reader = DataReader.FromBuffer(buffer);
    byte[] fileContent = new byte[reader.UnconsumedBufferLength];
    reader.ReadBytes(fileContent);
    string result = Encoding.UTF8.GetString(fileContent, 0, fileContent.Length);

    return result;
    }
    catch (Exception ex)
    {
    return "error";
    }
    }


  private async Task<HttpClient> PreparedClientAsync()
  {
   var filter = new Windows.Web.Http.Filters.HttpBaseProtocolFilter();

   filter.IgnorableServerCertificateErrors.Add(ChainValidationResult.Expired);
   filter.IgnorableServerCertificateErrors.Add(ChainValidationResult.Untrusted);
   filter.IgnorableServerCertificateErrors.Add(ChainValidationResult.InvalidName);

    HttpClient client = new HttpClient(filter);

    //I also handle other stuff here (client certificate, authentification), but the 
    lines above should allow the Httpclient to accept all certificates

    return client;
   }
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