python实现一个简单的ping工具方法

继上一篇计算checksum校验和，本章通过socket套接字，struct字节打包成二进制，select返回套接字的文件描述符的结合，实现一个简单的ping工具。

#!/usr/bin/python3.6.4
#!coding:utf-8
__author__ = 'Rosefinch'
__date__ = '2018/5/31 22:27'

import time
import struct
import socket
import select
import sys

def chesksum(data):
 """
 校验
 """
 n = len(data)
 m = n ％ 2
 sum = 0
 for i in range(0, n - m ,2):
   sum += (data[i]) + ((data[i+1]) << 8)#传入data以每两个字节（十六进制）通过ord转十进制，第一字节在低位，第二个字节在高位
 if m:
   sum += (data[-1])
 #将高于16位与低16位相加
 sum = (sum >> 16) + (sum & 0xffff)
 sum += (sum >> 16) #如果还有高于16位，将继续与低16位相加
 answer = ~sum & 0xffff
 #主机字节序转网络字节序列（参考小端序转大端序）
 answer = answer >> 8 | (answer << 8 & 0xff00)
 return answer

'''
 连接套接字,并将数据发送到套接字
 '''
def raw_socket(dst_addr,imcp_packet):
 rawsocket = socket.socket(socket.AF_INET,socket.SOCK_RAW,socket.getprotobyname("icmp"))
 send_request_ping_time = time.time()
 #send data to the socket
 rawsocket.sendto(imcp_packet,(dst_addr,80))
 return send_request_ping_time,rawsocket,dst_addr

'''
 request ping
 '''
def request_ping(data_type,data_code,data_checksum,data_ID,data_Sequence,payload_body):
 #把字节打包成二进制数据
 imcp_packet = struct.pack('>BBHHH32s',data_type,data_code,data_checksum,data_ID,data_Sequence,payload_body)
 icmp_chesksum = chesksum(imcp_packet)#获取校验和
 imcp_packet = struct.pack('>BBHHH32s',data_type,data_code,icmp_chesksum,data_ID,data_Sequence,payload_body)
 return imcp_packet
 '''
 reply ping
 '''
def reply_ping(send_request_ping_time,rawsocket,data_Sequence,timeout = 2):
 while True:
   started_select = time.time()
   what_ready = select.select([rawsocket], [], [], timeout)
   wait_for_time = (time.time() - started_select)
   if what_ready[0] == []: # Timeout
     return -1
   time_received = time.time()
   received_packet, addr = rawsocket.recvfrom(1024)
   icmpHeader = received_packet[20:28]
   type, code, checksum, packet_id, sequence = struct.unpack(
     ">BBHHH", icmpHeader
   )
   if type == 0 and sequence == data_Sequence:
     return time_received - send_request_ping_time
   timeout = timeout - wait_for_time
   if timeout <= 0:
     return -1

'''
 实现 ping 主机/ip
 '''
def ping(host):
 data_type = 8 # ICMP Echo Request
 data_code = 0 # must be zero
 data_checksum = 0 # "...with value 0 substituted for this field..."
 data_ID = 0 #Identifier
 data_Sequence = 1 #Sequence number
 payload_body = b'abcdefghijklmnopqrstuvwabcdefghi' #data
 dst_addr = socket.gethostbyname(host)#将主机名转ipv4地址格式，返回以ipv4地址格式的字符串，如果主机名称是ipv4地址，则它将保持不变
 print("正在 Ping {0} [{1}] 具有 32 字节的数据:".format(host,dst_addr))
 for i in range(0,4):
   icmp_packet = request_ping(data_type,data_code,data_checksum,data_ID,data_Sequence + i,payload_body)
   send_request_ping_time,rawsocket,addr = raw_socket(dst_addr,icmp_packet)
   times = reply_ping(send_request_ping_time,rawsocket,data_Sequence + i)
   if times > 0:
     print("来自 {0} 的回复: 字节=32 时间={1}ms".format(addr,int(times*1000)))
     time.sleep(0.7)
   else:
     print("请求超时。")

if __name__ == "__main__":
 if len(sys.argv) < 2:
   sys.exit('Usage: ping.py <host>')
 ping(sys.argv[1])

>python .\Ping_tool.py www.csdn.net
正在 Ping www.csdn.net [47.95.164.112] 具有 32 字节的数据:
来自 47.95.164.112 的回复: 字节=32 时间=39ms
来自 47.95.164.112 的回复: 字节=32 时间=40ms
来自 47.95.164.112 的回复: 字节=32 时间=40ms
来自 47.95.164.112 的回复: 字节=32 时间=39ms

引用：

https://docs.python.org/3/library/socket.html

https://docs.python.org/3/library/select.html#select.select

https://docs.python.org/3/library/struct.html

来源：https://blog.csdn.net/zhj082/article/details/80531628