Error Hostname not verified when sending request on Android

Igor Kravchenko 281

Hi!
I cannot send request to our web server. We use self-signed certificate. Exception throws on

using HttpResponseMessage response = await HttpClient.SendAsync(requestMessage, HttpCompletionOption.ResponseHeadersRead, cancellationToken);

I get Javax.Net.Ssl.SSLPeerUnverifiedException

Hostname *** not verified:  
    certificate: ***  
    subjectAltNames: ***

StackTrace (removed my calls because nothing interesting there):

   at Xamarin.Android.Net.AndroidMessageHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Xamarin.Android.Net/AndroidMessageHandler.cs:line 389  
   at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)

In our Xamarin Forms project the same code works fine.
Is it a bug? How can I resolve this?
Thanks.

Leon Lu (Shanghai Wicresoft Co,.Ltd.) 68,571 Reputation points Microsoft Vendor

2022-06-13T06:16:34.53+00:00

I notice you use self-signed certificate, do you bypass any certificate verification in the Xamarin.Forms?
You can try to install self-signed certificate (If you do not know how to install it, please use your favorite browser search: android use self-signed certificate) in your emulator then debug it to see if it works.

I find a similar thread: https://github.com/dotnet/runtime/issues/70434 Do you access the localhost URL? If so, please set a URL value targeting an external public API (such as "https://yourdomian.com/get")

Igor Kravchenko 281

No, I don't access localhost.
How can I share api address with you? I don't see a possibility to send private message.

Here is MAUI sample project.
Here is XF sample project.

I have implemented this for HttpClient:

protected virtual HttpClientHandler CreateHttpClientHandler()  
        {  
            var handler = new HttpClientHandler  
            {  
                ClientCertificateOptions = ClientCertificateOption.Manual,  
                ServerCertificateCustomValidationCallback = (httpRequestMessage, cert, cetChain, policyErrors) => { return true; }  
            };  
            return handler;  
        }

In XF project all works fine. In MAUI I get error.

Andriy Kravchenko 1 Reputation point

2022-06-13T11:30:19.617+00:00

protected virtual HttpClientHandler CreateHttpClientHandler()
{
var handler = new HttpClientHandler
{
ClientCertificateOptions = ClientCertificateOption.Manual,
ServerCertificateCustomValidationCallback = (httpRequestMessage, cert, cetChain, policyErrors) => { return true; }
};
return handler;
}
In MAUI this code on Windows platform works fine, but on Android - no. And this code works fine in Xamarin on both platforms.
Leon Lu (Shanghai Wicresoft Co,.Ltd.) 68,571 Reputation points Microsoft Vendor

2022-06-14T07:50:05.743+00:00

Yes, you cannot send private messages. This issue is only on your private api, you might need to open a support case, please contact our paid phone support at MS Support. You will get 1:1 support on that.

You can try to use androidclienthandler for android, https://learn.microsoft.com/en-us/xamarin/android/app-fundamentals/http-stack?tabs=windows#androidclienthandler
Igor Kravchenko 281 Reputation points

2022-06-14T09:30:08.057+00:00

Our API is common ASP.NET. There is nothing extra. Why in XF all works but not in MAUI?
I have uploaded new files with api address, please check it.
Xamarin Forms (working sample)
MAUI (with error)

P. S. I have tried AndroidClientHandler and AndroidMessageHandler and the result is "Hostname is not verified".
Leon Lu (Shanghai Wicresoft Co,.Ltd.) 68,571 Reputation points Microsoft Vendor

2022-06-16T09:58:48.803+00:00

I tried that, I get the same result as yours, even I enable TLS 1.2 for android,
But I run it in xamarin.forms, I find you get null result from this api. And your certificate is expired, it is valid from 4/4/2018 to 4/4/2019

2 answers

Sikandar Amla 1 Reputation point

2022-10-21T20:24:25.947+00:00

I have exact same issue. Self-signed certificate and trying to connect to a remote server (no localhost). @Igor Kravchenko Could you find any solution to this error?

Thanks
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Igor Kravchenko 281 Reputation points

2022-10-21T20:53:58.81+00:00

It was fixed in .Net 7 RC 2. Try to update Visual Studio Preview. Also check your maui project is targeted to .Net 7.
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Bruce (SqlWork.com) 56,026 Reputation points

2022-10-21T20:49:07.887+00:00

you can not override the ssl checking. you must install and trust the self cert in the android device.

google for instruction to instal a self signed cert for your device
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Igor Kravchenko 281 Reputation points

2022-10-21T21:01:09.413+00:00

No, we can do this

https://gist.github.com/Eilon/49e3c5216abfa3eba81e453d45cba2d4#file-devhttpsconnectionhelper-cs

Sikandar Amla 1 Reputation point

2022-10-22T07:16:18.8+00:00

@Igor Kravchenko isn't it a solution for the localhost?

Igor Kravchenko 281 Reputation points

2022-10-22T10:18:22.66+00:00

This helped me to send requests to our server with self signed certificate.
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