Fixes infinite loop during handshake in SslHandler in Android devices

Motivation:

On Android devices with version less than Lollipop, HarmonyJSSE is used for SSL. After completion of handshake, handshake status is NOT_HANDSHAKING instead of FINISHED. Also encrypting empty buffer after handshake should cause underflow exception and produce 0 bytes, but here it happily encrypts it causing for loop to never break

Modification:

Since 0 bytes should only be consumed in handshake process. Added a condition to break loop when 0 bytes are consumed and handshake status is NOT_HANDSHAKING

Result:

Sucessful ssl handshake on Android devices, no infinite loop now

handler/src/main/java/io/netty/handler/ssl/SslHandler.java

@@ -624,6 +624,12 @@ public class SslHandler extends ByteToMessageDecoder implements ChannelOutboundH
                 if (result.bytesProduced() == 0) {
                     break;
                 }
+
+                // It should not consume empty buffers when it is not handshaking
+                // Fix for Android, where it was encrypting empty buffers even when not handshaking
+                if (result.bytesConsumed() == 0 && result.getHandshakeStatus() == HandshakeStatus.NOT_HANDSHAKING) {
+                    break;
+                }
             }
         } catch (SSLException e) {
             setHandshakeFailure(ctx, e);