NullMessage implementation

libsession/src/main/java/org/session/libsession/messaging/messages/control/unused/NullMessage.kt

@@ -1,19 +1,37 @@
 package org.session.libsession.messaging.messages.control.unused
 
+import com.google.protobuf.ByteString
 import org.session.libsession.messaging.messages.control.ControlMessage
-import org.session.libsession.messaging.messages.control.ExpirationTimerUpdate
+import org.session.libsession.messaging.messages.control.TypingIndicator
+import org.session.libsignal.libsignal.logging.Log
 import org.session.libsignal.service.internal.push.SignalServiceProtos
+import java.security.SecureRandom
 
 class NullMessage() : ControlMessage() {
 
 
     companion object {
+        const val TAG = "NullMessage"
+
         fun fromProto(proto: SignalServiceProtos.Content): NullMessage? {
-            TODO("Not yet implemented")
+            if (proto.nullMessage == null) return null
+            return NullMessage()
         }
     }
 
     override fun toProto(): SignalServiceProtos.Content? {
-        TODO("Not yet implemented")
+        val nullMessageProto = SignalServiceProtos.NullMessage.newBuilder()
+        val sr = SecureRandom()
+        val paddingSize = sr.nextInt(512)
+        val padding = ByteArray(paddingSize)
+        nullMessageProto.padding = ByteString.copyFrom(padding)
+        val contentProto = SignalServiceProtos.Content.newBuilder()
+        try {
+            contentProto.nullMessage = nullMessageProto.build()
+            return contentProto.build()
+        } catch (e: Exception) {
+            Log.w(TAG, "Couldn't construct null message proto from: $this")
+            return null
+        }
     }
 }