Questions around TLS support on 2018.1

After changing Scripting Runtime Version to "Stable (.NET 4.x Equivalent)" there seems to be some incompatibilities with things that used to work before on the .NET Subset. Some are easy to workaround, but the missing TLS support seems problematic.

Here is the exception on Mac while building with ".NET Standard 2.0" Api Compatibility Level related to TLS:

NotSupportedException: Could not find TLS Provider: `Mono.AppleTls.AppleTlsProvider'.

  at Mono.Net.Security.MonoTlsProviderFactory.LookupProvider (System.String name, System.Boolean throwOnError) (at <29f77733112e45758bddddda41557ba4>:0)

  at Mono.Net.Security.MonoTlsProviderFactory.CreateDefaultProviderImpl () (at <29f77733112e45758bddddda41557ba4>:0)

  at Mono.Net.Security.MonoTlsProviderFactory.InitializeInternal () (at <29f77733112e45758bddddda41557ba4>:0)

  at Rethrow as NotSupportedException: TLS Support not available.

  at Mono.Net.Security.MonoTlsProviderFactory.InitializeInternal () (at <29f77733112e45758bddddda41557ba4>:0)

  at Mono.Net.Security.MonoTlsProviderFactory.GetProviderInternal () (at <29f77733112e45758bddddda41557ba4>:0)

  at Mono.Net.Security.MonoTlsProviderFactory.GetProvider () (at <29f77733112e45758bddddda41557ba4>:0)

  at Mono.Net.Security.NoReflectionHelper.GetProvider () (at <29f77733112e45758bddddda41557ba4>:0)

  at Mono.Security.Interface.MonoTlsProviderFactory.GetProvider () (at <7a3029b125ef46239232d401ab7fb89b>:0)

  at System.Net.Security.SslStream.GetProvider () (at <29f77733112e45758bddddda41557ba4>:0)

  at System.Net.Security.SslStream..ctor (System.IO.Stream innerStream, System.Boolean leaveInnerStreamOpen, System.Net.Security.RemoteCertificateValidationCallback userCertificateValidationCallback, System.Net.Security.LocalCertificateSelectionCallback userCertificateSelectionCallback) (at <29f77733112e45758bddddda41557ba4>:0)

  at (wrapper remoting-invoke-with-check) System.Net.Security.SslStream..ctor(System.IO.Stream,bool,System.Net.Security.RemoteCertificateValidationCallback,System.Net.Security.LocalCertificateSelectionCallback)

After changing the Api Compatibility Level to ".NET 4.x" this goes away on Mac so no big deal there.

Unfortunately even on Api Compatibility Level ".NET 4.x", it seems to still be missing on Android:

E/Unity   ( 8934): NotSupportedException: Could not find TLS Provider: `Mono.Net.Security.LegacyTlsProvider'.

E/Unity   ( 8934):   at Mono.Net.Security.MonoTlsProviderFactory.LookupProvider (System.String name, System.Boolean throwOnError) [0x00000] in <00000000000000000000000000000000>:0

E/Unity   ( 8934):   at Mono.Net.Security.MonoTlsProviderFactory.InitializeInternal () [0x00000] in <00000000000000000000000000000000>:0

E/Unity   ( 8934):   at Mono.Net.Security.MonoTlsProviderFactory.GetProviderInternal () [0x00000] in <00000000000000000000000000000000>:0

E/Unity   ( 8934):   at Mono.Net.Security.MonoTlsProviderFactory.GetProvider () [0x00000] in <00000000000000000000000000000000>:0

E/Unity   ( 8934):   at Mono.Security.Interface.MonoTlsProviderFactory.GetProvider () [0x00000] in <00000000000000000000000000000000>:0

E/Unity   ( 8934):   at System.Net.Security.SslStream..ctor (System.IO.Stream innerStream, System.Boolean leaveInnerStreamOpen, System.Net.Security.RemoteCertificateValidationCallback userCertificateValidationCallback, System.Net.Security.LocalCertificateSelectionCallback userCertificateSelectionCallback) [0x00000] in

Of note the same code on Android, iOS, Mac and Windows has zero issues with TLS under .NET Subset on Unity 5.6. Does anyone know if this is something that is actively being worked on, never going to be added to the upgraded runtime, or something else entirely?

 

Update:

I have tracked the Android issue down to an IL2CPP problem. If I switch the scripting backend to Mono on Android the exception no longer occurs.

Working on submitting a bug report but it's also hanging on "Uploading the report" so not sure what's going on.

EDIT: Finally got the bug report submitted. It looks like it was including the Library folder (800 MB even for an empty project) and Temp/StagingArea which was adding another 1GB to the bug report. Those folders must be big even with very little scripts or assets due to building the project for Android IL2CPP.

Cleared both those folders before submitting and got it down to 40MB.

 

I still get an error logged to adb logcat during the SslStream constructor under Mono in 2018.1:

E/Unity (23382): Unable to find libc

But no exception and it definitely reads and writes data using the SslStream but eventually the app just crashes when running under Mono with a bunch of really random things in logcat, nothing I can pin it to yet.

However, if the SslStream wasn't working the data wouldn't even be getting decrypted properly and the messages are definitely making it through intact.

EDIT: Looks like the crashes are just higher memory usage under 2018.1 vs 5.6, so will have to dig into what's using more memory. Grabbed a higher end device and it works just fine.

 

Adding the following to link.xml allows SslStream to work on Android IL2CPP as well under 4.x on 2018.1:

<assembly fullname="System">

<type fullname="Mono.Net.Security.LegacyTlsProvider" preserve="all" />

</assembly>

I couldn't figure out which assembly Mono.Net.Security was in and then just tried System on a whim since it is the DLL that has System.Net.Security and it worked!