python检测远程udp端口是否打开

import socket
import threading
import time
import struct
import Queue
 
queue = Queue.Queue()
 
def udp_sender(ip,port):
    try:
        ADDR = (ip,port)
        sock_udp = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
        sock_udp.sendto("abcd...",ADDR)
        sock_udp.close()
    except:
        pass
 
def icmp_receiver(ip,port):
    icmp = socket.getprotobyname("icmp")
    try:
        sock_icmp = socket.socket(socket.AF_INET,socket.SOCK_RAW,icmp)
    except socket.error,(errno,msg):
        if errno == 1:
            # Operation not permitted
            msg = msg + (
                " - Note that ICMP messages can only be sent from processes"
                " running as root."
            )
            raise socket.error(msg)
        raise # raise the original error
    sock_icmp.settimeout(3)
    try:
        recPacket,addr = sock_icmp.recvfrom(64)
    except:
        queue.put(True)
        return
    icmpHeader = recPacket[20:28]
    icmpPort = int(recPacket.encode('hex')[100:104],16)
    head_type,code,checksum,packetID,sequence = struct.unpack(
            "bbHHh",icmpHeader
    )
    sock_icmp.close()
    if code == 3 and icmpPort == port and addr[0] == ip:
        queue.put(False)
    return
 
def checker_udp(ip,port):
 
    thread_udp = threading.Thread(target=udp_sender,args=(ip,port))
    thread_icmp = threading.Thread(target=icmp_receiver,port))
 
    thread_udp.daemon= True
    thread_icmp.daemon = True
 
    thread_icmp.start()
    time.sleep(0.1)
    thread_udp.start()
 
    thread_icmp.join()
    thread_udp.join()
    return queue.get(False)
 
if __name__ == '__main__':
    import sys
    print checker_udp(sys.argv[1],int(sys.argv[2]))