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
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