import socket

def run_udp_server():
    server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    server.bind(('0.0.0.0', 10001))
    print("UDP server started on port 10001")
    print("Waiting for messages...")

    try:
        while True:
            data, addr = server.recvfrom(1024)
            message = data.decode().strip()
            print(f"Message from {addr}: '{message}'")
            
            if message.upper() == 'EXIT':
                print("Received EXIT command, shutting down")
                break
            
            modified_message = f"UDP-ECHO: {message.upper()} [modified]"
            server.sendto(modified_message.encode(), addr)
            print(f"Sent response to client: '{modified_message}'")
            
    except KeyboardInterrupt:
        print("\nServer stopped by user")
    finally:
        server.close()
        print("Server socket closed")

if __name__ == "__main__":
    run_udp_server()