public int uid() {
        return mSession.uid;
    }
Returns the identifier of this session's process uid. This value is not guaranteed, it is up
to {@link NetBareConfig#dumpUid}. And if dumps the uid failed, it will return 0.

@return The session's process uid.
netbare-core/src/main/java/com/github/megatronking/netbare/gateway/SessionTunnelFlow.java