python简易版 ping

#!/usr/bin/env python  
#-*- coding:utf-8 -*-  
#Author:left_left  
import sys  
import os  
import time  
import select  
import struct  
import socket  
 
def data_format(seq, id):  
    sum = id + seq + 8 
    sum = (sum >> 16) + (sum & 0xffff)  
    sum = sum + (sum >> 16)  
    sum = sum ^  0xffff 
    header = struct.pack('bbHHh', 8, 0, sum,  
            id, seq)  
    return header  
 
def time_format():  
    if os.name == "nt":  
        return time.clock()  
    else:  
        return time.time()  
 
def recv_data(chk, t, s):  
    while 1:  
        r, w, x = select.select([s], [], [], 1)  
          
        if s in r:  
            d = s.recvfrom(1024)  
            p = d[0]  
            if p[24:28] == chk:  
                t = time_format() - t  
                print "%d bytes from %s: icmp_seq=%d ttl=%d time=%.3f ms" % (  
                        len(p), d[1][0], struct.unpack('h', p[26:28])[0], int(ord(p[8])), t*1000)  
                return 1 
            else:  
                continue 
        else:  
            print "Request timed out ..." 
            return 0 
   
def ping(host):  
    i = 0 
    sent = 0 
    suc_num = 0 
    id = os.getpid()  
 
    try:  
        addr = socket.gethostbyname(host)  
        if not addr:  
            raise   
    except:  
        print "Please input the correct host ..." 
        exit(1)  
      
    try:  
        while 1:  
            sent += 1 
            s = socket.socket(socket.AF_INET, socket.SOCK_RAW, 1)  
            data = data_format(sent, id)  
            t = time_format()  
            try:  
                s.sendto(data, (addr, 1))  
            except socket.error:  
                print "Count connect %s" % host  
                exit(1)  
 
            i = recv_data(data[-4:], t, s)  
            suc_num += i  
            time.sleep(1)  
    except KeyboardInterrupt:  
        print "-------- %s ping statistics --------" % host  
        print r"%d packets transmitted, %d received, %d%% packet loss" %(sent,   
                suc_num, (sent-suc_num)*100/ sent )  
 
def main():  
    try:  
        host = sys.argv[1]  
    except IndexError:  
        print "Missing host ..." 
        exit(1)  
 
    ping(host)  
 
if __name__ == '__main__':