python网络作业：使用python的socket库实现ICM

ICMP ping是您遇到过的最常见的网络扫描类型。 打开命令行提示符或终端并输入ping www.google.com非常容易。

为什么要在python中实现？

• 很多名牌大学喜欢考试用python的socket库实现ICMP协议的ping
• 个别环境没有ping

直接上代码：

#!/usr/bin/python3
# -*- coding: utf-8 -*-
# 技术支持：https://www.jianshu.com/u/69f40328d4f0 
# 技术支持 https://china-testing.github.io/
# https://github.com/china-testing/python-api-tesing/blob/master/practices/ping.py
# 讨论钉钉免费群21745728 qq群144081101 567351477
# CreateDate: 2018-11-22

import os 
import argparse 
import socket
import struct
import select
import time


ICMP_ECHO_REQUEST = 8 # Platform specific
DEFAULT_TIMEOUT = 2
DEFAULT_COUNT = 4 


class Pinger(object):
    """ Pings to a host -- the Pythonic way"""

    def __init__(self, target_host, count=DEFAULT_COUNT, timeout=DEFAULT_TIMEOUT):
        self.target_host = target_host
        self.count = count
        self.timeout = timeout


    def do_checksum(self, source_string):
        """  Verify the packet integritity """
        sum = 0
        max_count = (len(source_string)/2)*2
        count = 0
        while count < max_count:

            val = source_string[count + 1]*256 + source_string[count]                   
            sum = sum + val
            sum = sum & 0xffffffff 
            count = count + 2

        if max_count<len(source_string):
            sum = sum + ord(source_string[len(source_string) - 1])
            sum = sum & 0xffffffff 

        sum = (sum >> 16)  +  (sum & 0xffff)
        sum = sum + (sum >> 16)
        answer = ~sum
        answer = answer & 0xffff
        answer = answer >> 8 | (answer << 8 & 0xff00)
        return answer

    def receive_pong(self, sock, ID, timeout):
        """
        Receive ping from the socket.
        """
        time_remaining = timeout
        while True:
            start_time = time.time()
            readable = select.select([sock], [], [], time_remaining)
            time_spent = (time.time() - start_time)
            if readable[0] == []: # Timeout
                return

            time_received = time.time()
            recv_packet, addr = sock.recvfrom(1024)
            icmp_header = recv_packet[20:28]
            type, code, checksum, packet_ID, sequence = struct.unpack(
       "bbHHh", icmp_header
   )
            if packet_ID == ID:
                bytes_In_double = struct.calcsize("d")
                time_sent = struct.unpack("d", recv_packet[28:28 + bytes_In_double])[0]
                return time_received - time_sent

            time_remaining = time_remaining - time_spent
            if time_remaining <= 0:
                return


    def send_ping(self, sock,  ID):
        """
        Send ping to the target host
        """
        target_addr  =  socket.gethostbyname(self.target_host)

        my_checksum = 0

        # Create a dummy heder with a 0 checksum.
        header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, my_checksum, ID, 1)
        bytes_In_double = struct.calcsize("d")
        data = (192 - bytes_In_double) * "Q"
        data = struct.pack("d", time.time()) + bytes(data.encode('utf-8'))

        # Get the checksum on the data and the dummy header.
        my_checksum = self.do_checksum(header + data)
        header = struct.pack(
      "bbHHh", ICMP_ECHO_REQUEST, 0, socket.htons(my_checksum), ID, 1
  )
        packet = header + data
        sock.sendto(packet, (target_addr, 1))


    def ping_once(self):
        """
        Returns the delay (in seconds) or none on timeout.
        """
        icmp = socket.getprotobyname("icmp")
        try:
            sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
        except socket.error as e:
            if e.errno == 1:
                # Not superuser, so operation not permitted
                e.msg +=  "ICMP messages can only be sent from root user processes"
                raise socket.error(e.msg)
        except Exception as e:
            print ("Exception: %s" %(e))

        my_ID = os.getpid() & 0xFFFF

        self.send_ping(sock, my_ID)
        delay = self.receive_pong(sock, my_ID, self.timeout)
        sock.close()
        return delay


    def ping(self):
        """
        Run the ping process
        """
        for i in range(self.count):
            print ("Ping to %s..." % self.target_host,)
            try:
                delay  =  self.ping_once()
            except socket.gaierror as e:
                print ("Ping failed. (socket error: '%s')" % e[1])
                break

            if delay  ==  None:
                print ("Ping failed. (timeout within %ssec.)" % self.timeout)
            else:
                delay  =  delay * 1000
                print ("Get pong in %0.4fms" % delay)



if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Python ping')
    parser.add_argument('host', action="store", help=u'主机名')
    given_args = parser.parse_args()  
    target_host = given_args.host
    pinger = Pinger(target_host=target_host)
    pinger.ping()

参考资料

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• 最新代码地址

执行

注意要有root或管理员权限：

# python3 ping.py china-testing.github.io
Ping to china-testing.github.io...
Get pong in 160.7175ms
Ping to china-testing.github.io...
Get pong in 160.8465ms
Ping to china-testing.github.io...
Get pong in 12.0983ms
Ping to china-testing.github.io...
Get pong in 161.3324ms
# python3 ping.py www.so.com
Ping to www.so.com...
Get pong in 29.0303ms
Ping to www.so.com...
Get pong in 28.8599ms
Ping to www.so.com...
Get pong in 28.9860ms
Ping to www.so.com...
Get pong in 29.0167ms