python实现的ping的代码

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#!/usr/bin/env python#coding:utf-8import os, sys, socket, struct, select, time# From /usr/include/linux/icmp.h; your milage may vary.ICMP_ECHO_REQUEST = 8 # Seems to be the same on Solaris.def checksum(source_string):    """    I'm not too confident that this is right but testing seems    to suggest that it gives the same answers as in_cksum in ping.c    """    sum = 0    count = 0    while count> 16)  +  (sum & 0xffff)    sum = sum + (sum >> 16)    answer = ~sum    answer = answer & 0xffff    # Swap bytes. Bugger me if I know why.    answer = answer >> 8 | (answer << 8 & 0xff00)    return answerdef receive_one_ping(my_socket, ID, timeout):    """    receive the ping from the socket.    """    timeLeft = timeout    while True:        startedSelect = time.time()        whatReady = select.select([my_socket], [], [], timeLeft)        howLongInSelect = (time.time() - startedSelect)        if whatReady[0] == []: # Timeout            return        timeReceived = time.time()        recPacket, addr = my_socket.recvfrom(1024)        icmpHeader = recPacket[20:28]        type, code, checksum, packetID, sequence = struct.unpack(            "bbHHh", icmpHeader        )        if packetID == ID:            bytesInDouble = struct.calcsize("d")            timeSent = struct.unpack("d", recPacket[28:28 + bytesInDouble])[0]            return timeReceived - timeSent        timeLeft = timeLeft - howLongInSelect        if timeLeft <= 0:            returndef send_one_ping(my_socket, dest_addr, ID):    """    Send one ping to the given >dest_addr<.    """    dest_addr  =  socket.gethostbyname(dest_addr)    # Header is type (8), code (8), checksum (16), id (16), sequence (16)    my_checksum = 0    # Make a dummy heder with a 0 checksum.    header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, my_checksum, ID, 1)  #压包    #a1 = struct.unpack("bbHHh",header)    #my test    bytesInDouble = struct.calcsize("d")    data = struct.pack("d", time.time()) + data    # Calculate the checksum on the data and the dummy header.    my_checksum = checksum(header + data)    # Now that we have the right checksum, we put that in. It's just easier    # to make up a new header than to stuff it into the dummy.    header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, socket.htons(my_checksum), ID, 1)    packet = header + data    my_socket.sendto(packet, (dest_addr, 1)) # Don't know about the 1def do_one(dest_addr, timeout):    """    Returns either the delay (in seconds) or none on timeout.    """    icmp = socket.getprotobyname("icmp")    try:        my_socket = 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    my_ID = os.getpid() & 0xFFFF    send_one_ping(my_socket, dest_addr, my_ID)    delay = receive_one_ping(my_socket, my_ID, timeout)    my_socket.close()    return delaydef verbose_ping(dest_addr, timeout = 2, count = 100):    """    Send >count< ping to >dest_addr< with the given >timeout< and display    the result.    """    for i in xrange(count):        print "ping %s..." % dest_addr,        try:            delay  =  do_one(dest_addr, timeout)        except socket.gaierror, e:            print "failed. (socket error: '%s')" % e[1]            break        if delay  ==  None:            print "failed. (timeout within %ssec.)" % timeout        else:            print "get ping in %0.4fms" % delayif __name__ == '__main__':    verbose_ping("www.163.com",2,1)