Develop Reference

SignalR v2.3.0 in Android

I have a MVC .NET application that uses signalR.
I tried to download this client:
https://github.com/Gurgen/SignalR-.net-core-android-client
I ran it on my device. Pressed the connect button. But kept getting an exception.
Debugging it I found that I had to change this line
String connectionId = jsonElement.getAsJsonObject().get("connectionId").getAsString();
to this
String connectionId = jsonElement.getAsJsonObject().get("ConnectionId").getAsString();
I am already starting to feel like this client doesn't support v2.3.0 of the SignalR library in my .NET application. Any way the next exception is caused by this line:
JsonElement availableTransportsElements = jsonElement.getAsJsonObject().get("availableTransports");
I had a look at the JSON returned by SignalR and there is no such element as "availableTransports". This is what it returned
{ "Url":"/signalr/hubs/auth","ConnectionToken":"zzK0SAWXNEB1pLY2VYHWPYTMcyJIX8PnhKfLRP9fij5xbY2jDIaDyKuZQa5RvHt+KSe6h1PD9JC+RL7V2nhPzevktK781hL7ndAnZqAe3E12GawCVddFUI4R9FLDE//L","ConnectionId":"9cb5ff73-14d3-4e59-8b14-d92e47bbe948","KeepAliveTimeout":20.0,"DisconnectTimeout":30.0,"ConnectionTimeout":110.0,"TryWebSockets":false,"ProtocolVersion":"1.2","TransportConnectTimeout":5.0,"LongPollDelay":0.0 }
Ok my question, has anyone used this library? Or is there another Android library I can use that is compatible? I am new to SignalR but from what the server sent does the .NET application support websockets? I want my Android client to connect using websockets.
UPDATE
OK I have discovered that WebSocket Protocol feature was not installed in IIS. I have done that now and now this is what is returned, however the client cannot still connect to it.
{ "Url":"/signalr/hubs/auth","ConnectionToken":"6CkVnCK9KmbDemtXY/S+zCyBUdaYbaK8WmQxIw6+JxjeEzWCP7BPTiItqgvzu+hhaf6kIS4NlPln8LJLfS95UbUG4rF/8C6Y5D7eq2aKCLEU6up/c4l8YvMKheodRsKy","ConnectionId":"abe2cdca-e237-4cbd-8523-98af8c864b9b","KeepAliveTimeout":20.0,"DisconnectTimeout":30.0,"ConnectionTimeout":110.0,"TryWebSockets":true,"ProtocolVersion":"1.2","TransportConnectTimeout":5.0,"LongPollDelay":0.0}
That is a step closer as now TryWebSockets is true.

Cannot send TLS 1.2 with Xamarin.Forms and VisualStudio 2017

I am trying to send a POST transaction from Xamarin.Forms using TLS1.2 but I see them arriving to the server as TLS 1.1.
I have configured Android options:
HttpClient impletemtation as Android
SSL/TLS implementation as Native TLS 1.2+
I am implementing and executing in VisualStudio 2017, and using Android 6.0 in the emulator.
Regarding the code, I set some enviroment variables:
System.Environment.SetEnvironmentVariable("MONO_TLS_PROVIDER‌​", "btls");
System.Environment.SetEnvironmentVariable("XA_TLS_PROVIDER‌​", "btls");
System.Environment.SetEnvironmentVariable("XA_HTTP_CLIENT_HANDLER_TYPE", "Xamarin.Android.Net.AndroidClientHandler");
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
Finally, POST is sent with:
using (HttpClient client = new HttpClient())
or
using (HttpClient client = new HttpClient(new NativeMessageHandler()))
or
using (HttpClient client = new HttpClient(new Xamarin.Android.Net.AndroidClientHandler()))
{
try
{
HttpResponseMessage responseHttp = await client.PostAsync(new Uri(new Uri(Constants.ApiBaseUrl), "authorize"), content);
...
Where Constants.ApiBaseUrl contains a url with https://<> format.
The problem is, when POST is sent I have no exceptions, but in my server I see with Wireshark the transaction as:
I have also tried in other way, using:
HttpWebRequest httpWebRequest = WebRequest.CreateHttp(new Uri(new Uri(Constants.ApiBaseUrl), "authorize"));
httpWebRequest.Method = "POST";
httpWebRequest.Credentials = CredentialCache.DefaultNetworkCredentials;
Stream sw = httpWebRequest.GetRequestStream();
sw.Write(contentByte, 0, contentByte.Length);
HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
With and without my own certificates using:
httpWebRequest.ClientCertificates = cryptoSvc.x509HostCertificates;
In this case, if I use
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
I get the exception
RestService-SendJsonDataAsync ERROR: Error: SecureChannelFailure
(**Ssl error:100000f0:SSL routines:OPENSSL_internal:UNSUPPORTED_PROTOCOL**
at /Users/builder/jenkins/workspace/xamarin-android/xamarin-android/external/mono/external/boringssl/ssl/handshake_client.c:808)
Without that line it is also arriving as TLS1.1.
Does anyone have any idea or suggestion about what is wrong in my case, please?
Thanks so much for your time and help.

I believe in Android 6.0, TLS 1.2 is enabled by default:
https://developer.android.com/reference/javax/net/ssl/SSLSocket.html
But, you have BTLS configuration and Native TLS 1.2, I think these are conflicting. BTLS is the Boring TLS implementation, designed to provide TLS 1.2 support on older versions of Android. I think you can safely remove those lines.
I'd first confirm what the server is allowing in terms of security and if possible have the server limit HTTPS connections to only TLS 1.2.
If you'd like to try forcing only TLS 1.2 connections on the client side, take a look at this answer (note this is in Java, but the process is the same):
How to set TLS version on apache HttpClient

I was able to work around this problem by downloading and installed VS 2022 Community - Preview. I then created a MAUI .net app and used the same code that I used in VS 2019.

The authentication or decryption has failed error when making an SSL webservice call using Xamarin and an Android Emulator

I am developing a Xamarin mobile Android app. For data access, the app uses a Portable class library to make webservice calls to the back end. I’m using the Portable class library so that I can share it with an iOS version of the mobile app later. The data is sensitive and requires SSL for all communications which is configured in the WebAPI web service project. It uses oAuth for authentication.
The challenge I’m running into is that the initial request to authenticate is failing when I run it locally with the following error:
System.Net.Http.HttpRequestException: An error occurred while sending the request
System.Net.WebException: Error: TrustFailure (The authentication or decryption has failed.)
System.IO.IOException: The authentication or decryption has failed.
Some additional information:
I am using the following built in Visual Studio emulator and version - Android_Accelerated_x86 (Android 6.0 – API 23).
I am currently running it on localhost and following is the code snippet for this call:
HttpClient client = new HttpClient(new NativeMessageHandler())
{
BaseAddress = new Uri("https://10.0.2.2:44342/") // I also tried installing it on IIS and using port 443 on localhost. Same problem.
};
var content = new StringContent("grant_type=password&username=[USER_NAME]&password=[PASSWORD]", Encoding.UTF8, "application/json");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = await client.PostAsync("Token", content).ConfigureAwait(false);
if (response.IsSuccessStatusCode)
{
var data = await response.Content.ReadAsStringAsync();
var stuffList = JsonConvert.DeserializeObject<List<Stuff>>(data);
return stuffList;
}
else
{
return new List<Stuff>();
}
The call works when I test it through Fiddler on localhost, so I know that everything is configured correctly on the web service end and with authentication. But from the emulator my understanding is that I need to use IP address 10.0.2.2. I have create a self-signed cert and that hasn’t seemed to help.
I have also attempted to use Fiddler as a middleman, but I’m not seeing any activity in Fiddler when I run the app locally. I have also tried to change the network settings of the emulator, but it doesn’t appear to be having any affect. The base emulator seems to be fairly limited in these settings, but I also don’t want to pay for a more advanced one at this point in time. I have seen a number of posts with similar issues, but none of the existing recommendations that I have found are helping. Any help would be greatly appreciated!

Using http instead of https in AppEngine endpoint to avoid SSLHandshakeException

My problem is the same as SSLHandshakeException when trying to reach app engine endpoint (so yes, it's a duplicate to that extent). The answer there says that I need to change from https to http. So how do I do that? I am using java app engine.
My web.xml does not have anywhere
<user-data-constraint>
<transport-guarantee>CONFIDENTIAL</transport-guarantee>
</user-data-constraint>
Also in the android client, I connect to the server with
MyServer service = MyServer.Builder builder = new MyServer.Builder(
AndroidHttp.newCompatibleTransport(),
new AndroidJsonFactory(),
null
);
to be clear
I can confirm that my code is indeed using https, I look into the generated source and found:
public Builder(HttpTransport transport, JsonFactory jsonFactory, HttpRequestInitializer httpRequestInitializer) {
super(transport, jsonFactory,
"https://mycompanyserver.appspot.com/_ah/api/", "server/1/",
httpRequestInitializer, false);
}
I just don't know how to prevent it from asking for https.
I am able to reach the site from the browser, and so the problem may be android studio server certificate
Do I need to add appengine server certificate to android studio? When I go to android studio > Preferences >Server Certificates, under Accepted Certificates I see N/A > untangle. How would I go about adding my app engine certificate to android studio?
And since I added my Appengine module using the android studio instructions, why was it not auto-included?

Creating a Google HTTP Transport Object for Android HTTP Request

I'm creating an Android app and trying to use Google Places API through Google APIs Client. I've been following this example:
http://ddewaele.blogspot.com/2011/05/introducing-google-places-api.html
I'm having problems creating a HTTP Transport Object to use in creating the HTTP Request Factory. Everything compiles fine in eclipse, but when I debug while running on my phone, I get a classnotfound on the first line here:
HttpTransport transport = new ApacheHttpTransport();
HttpRequestFactory httpRequestFactory = createRequestFactory(transport);
public static HttpRequestFactory createRequestFactory(HttpTransport transport) {
return transport.createRequestFactory(new HttpRequestInitializer() {
#Override
public void initialize(HttpRequest request) throws IOException {
request.headers.authorization = "...";
}
});
}
According to the JavaDoc for the HTTP Transport Class:
Android:
Starting with SDK 2.3, strongly recommended to use
com.google.api.client.javanet.NetHttpTransport. Their Apache HTTP Client
implementation is not as well maintained.
For SDK 2.2 and earlier, use com.google.api.client.apache.ApacheHttpTransport.
com.google.api.client.javanet.NetHttpTransport
is not recommended due to some bugs in
the Android SDK implementation of
HttpURLConnection.
I'm running on 2.2, so I tried using the ApacheHTTPTransport. I've also tried the NetHTTPTransport, but I get the same thing (classnotfound).
Any ideas/examples?
Thanks!

In order to run the Places API in an Android environment using the Google APIs Client, you'll need to have the following dependencies in your Android project :
M2_REPO/commons-codec/commons-codec/1.3/commons-codec-1.3.jar
M2_REPO/commons-logging/commons-logging/1.1.1/commons-logging-1.1.1.jar
M2_REPO/com/google/api/client/google-api-client/1.4.1-beta/google-api-client-1.4.1-beta.jar
M2_REPO/com/google/api/client/google-api-client-googleapis/1.4.1-beta/google-api-client-googleapis-1.4.1-beta.jar
M2_REPO/com/google/code/gson/gson/1.6/gson-1.6.jar
M2_REPO/com/google/guava/guava/r08/guava-r08.jar
M2_REPO/org/apache/httpcomponents/httpclient/4.0.3/httpclient-4.0.3.jar
M2_REPO/org/apache/httpcomponents/httpcore/4.0.1/httpcore-4.0.1.jar
M2_REPO/org/codehaus/jackson/jackson-core-asl/1.6.5/jackson-core-asl-1.6.5.jar
M2_REPO/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar