Xamarin/Mono Mac - Handshake failure in AppStore build

Question

I have an application which now needs to be deployed to the app store, as it is slowly becoming unavoidable thanks to Gatekeeper.

Only problem is that web requests seem to fail, in the sense that they aren't even being fired.

The following code snippet has been pulled from a Xamarin Bugzilla article, and succeeds when built for Release and Debug;

            try
            {
                WebClient test = new WebClient();
                Console.WriteLine("Testing SSL GET...");
                string testresponse = test.DownloadString(checkFileUrl);
                Console.WriteLine("testresponse = " + testresponse);
            } catch (Exception e)
            {
                Console.WriteLine(e.Message);
                Console.WriteLine(e.InnerException.Message);
            }

However, when I flip over to AppStore build, with sandboxing and Network IO Entitlements, the request never gets sent out, as verified by Charles in Non-SSL decryption mode. The following gets spat out from the console;

Testing SSL GET...
Error getting response stream (Write: The authentication or decryption has failed.): SendFailure
The authentication or decryption has failed.

This seems to be the problem, as we use SOAP calls made to an IIS service to perform actions, the first of which is logging in. For Debug and Release, login works fine, as the calls are completed. Once again, the AppStore build doesn't even attempt to make contact.

Certificates are valid, and CA's installed in my keychain.

Leading up to this, I was getting some exceptions in the code (in Debug) such as;

System.Exception..ctor (message="invalid encoding specification.") in /private/tmp/source/bockbuild-mono-3.2.6/profiles/mono-mac-xamarin/build-root/mono-3.2.6/mcs/class/corlib/System/Exception.cs:81

and

System.Exception..ctor (message="Store Root doesn't exists.") in /private/tmp/source/bockbuild-mono-3.2.6/profiles/mono-mac-xamarin/build-root/mono-3.2.6/mcs/class/corlib/System/Exception.cs:81

and

System.Exception..ctor (message="Store CA doesn't exists.") in /private/tmp/source/bockbuild-mono-3.2.6/profiles/mono-mac-xamarin/build-root/mono-3.2.6/mcs/class/corlib/System/Exception.cs:81

which still leads me to believe it is a Certificate issue. The test URL is an S3 link, and the login server is an EC2 instance with valid Certificates.

Cheers.

Answer 1

Check how your application is being packaged.

By default, when building your project (either in Xamarin Studio or Visual Studio), it will call a tool called mtouch that includes a linker for managed code. This tool is used to remove features from the class libraries that the application is not using.

Or so mtouch would like you to believe.

The default option of the linker behaviour is to Link all assembiles. This will use mtouch to try to make the application as small as possible by modifying user code. This can and will break code that uses features in a way that mtouch cannot detect (such as webservices, reflection or serialisation).

The workaround that I have used is to disable linking. By changing the linker behaviour to Don't Link, this will make sure that no assemblies are modified.

You can find the menu to do this by right-clicking on the relevant project, and selecting Options:

Xamarin Studio - Project Options window

Try changing the linker behaviour to Don't Link (as shown above) and rebuild.

More information

Xamarin Guides - Linker with iOS