TFTP_C line 101， the 2nd argument is supposed to be ""

[xzdera]

	char last_recv_message[MAXBUFLEN];
	strcpy(last_recv_message, "");
	char last_sent_ack[10];
	strcpy(last_sent_ack, message);

--------------------------->
char last_recv_message[MAXBUFLEN];
strcpy(last_recv_message, "");
char last_sent_ack[10];
strcpy(last_sent_ack, "");