Android JNI trying to get SSLEngine.getApplicationProtocol but it was introduced in API 29

[akoeplinger]

Found this while looking at why a workitem crashed and saw we were running on an Android 28 device (https://github.com/dotnet/core-eng/issues/13102).

The implementation tries to access the method even though it was only introduced in API 29: https://developer.android.com/reference/javax/net/ssl/SSLEngine#getApplicationProtocol()

runtime/src/libraries/Native/Unix/System.Security.Cryptography.Native.Android/pal_jni.c

Line 970 in 6ab1cee

g_SSLEngineGetApplicationProtocol = GetMethod(env, false, g_SSLEngine, "getApplicationProtocol", "()Ljava/lang/String;");

We should update the implementation to use GetOptionalMethod instead and handle the missing API case appropriately.

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Issue Details

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Found this while looking at why a workitem crashed and saw we were running on an Android 28 device (https://github.com/dotnet/core-eng/issues/13102).

The implementation tries to access the method even though it was only introduced in API 29: https://developer.android.com/reference/javax/net/ssl/SSLEngine#getApplicationProtocol()

runtime/src/libraries/Native/Unix/System.Security.Cryptography.Native.Android/pal_jni.c

Line 970 in 6ab1cee

g_SSLEngineGetApplicationProtocol = GetMethod(env, false, g_SSLEngine, "getApplicationProtocol", "()Ljava/lang/String;");

We should update the implementation to use GetOptionalMethod instead and handle the missing API case appropriately.

Author:	akoeplinger
Assignees:	-
Labels:	area-System.Security, os-android
Milestone:	6.0.0

[akoeplinger]

Hm this might actually be something we want to fix soon (i.e. backport to preview5) since Xamarin.Android now calls loadLibrary() on the crypto library early in application startup which means we'll fail on any Android < 29 device.

This probably wasn't noticed before because we didn't have asserts that failed in release builds before #52449