python实现ping程序实验

Python实现Ping程序实验

Ping是一种常见的网络工具，用于测试网络连接的可用性和延迟。在本文中，我们将介绍如何使用Python语言实现一个Ping程序，并通过代码示例演示其使用方式。

什么是Ping？

Ping是一种基于Internet控制报文协议（ICMP）的网络工具。它发送一个ICMP Echo Request消息到目标主机，并等待目标主机返回ICMP Echo Reply消息。通过测量往返时间（RTT），Ping可以估计目标主机的连接质量和延迟。

实现Ping程序

实现思路

要实现一个Ping程序，我们需要完成以下步骤：

1. 构建ICMP Echo Request消息
2. 发送该消息到目标主机
3. 等待目标主机返回ICMP Echo Reply消息
4. 计算往返时间（RTT）

代码示例

下面是一个使用Python实现Ping程序的代码示例：

import os
import platform
import struct
import select
import socket
import time

ICMP_ECHO_REQUEST = 8  # ICMP Echo Request类型

def calculate_checksum(source_string):
    """
    计算校验和
    """
    sum = 0
    countTo = (len(source_string) / 2) * 2
    count = 0
    while count < countTo:
        thisVal = ord(source_string[count + 1]) * 256 + ord(source_string[count])
        sum = sum + thisVal
        sum = sum & 0xffffffff
        count = count + 2

    if countTo < 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 create_packet():
    """
    创建ICMP Echo Request消息
    """
    # Header部分，共8字节
    icmp_type = ICMP_ECHO_REQUEST
    icmp_code = 0
    icmp_checksum = 0
    icmp_identifier = os.getpid()
    icmp_sequence = 1
    header = struct.pack("!BBHHH", icmp_type, icmp_code, icmp_checksum, icmp_identifier, icmp_sequence)

    # Data部分，共56字节
    data = "Ping" * 13

    # 计算校验和
    icmp_checksum = calculate_checksum(header + data)

    # 重新构造ICMP Echo Request消息
    packet = struct.pack("!BBHHH", icmp_type, icmp_code, icmp_checksum, icmp_identifier, icmp_sequence) + data
    return packet

def send_ping(destination, timeout):
    """
    发送Ping消息并等待响应
    """
    try:
        # 创建socket
        icmp = socket.getprotobyname("icmp")
        sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)

        # 设置超时时间
        sock.settimeout(timeout)

        # 构建ICMP Echo Request消息
        packet = create_packet()

        # 发送消息
        sock.sendto(packet, (destination, 0))

        # 记录发送时间
        start_time = time.time()

        # 等待响应
        ready, _, _ = select.select([sock], [], [], timeout)

        # 计算往返时间
        end_time = time.time()
        rtt = (end_time - start_time) * 1000

        if ready:
            data, addr = sock.recvfrom(1024)
            return rtt
        else:
            return None
    except socket.gaierror:
        print("Hostname could not be resolved.")
    except socket.error:
        print("Error occurred while creating socket.")

def ping(destination, count, timeout):
    """
    发送多个Ping消息并计算平均往返时间
    """
    total_rtt = 0
    lost_count = 0

    for i in range(count):
        rtt = send_ping(destination, timeout)
        if rtt is None:
            lost_count += 1
        else:
            total_rtt += rtt
            print(f"Reply from {destination}: time={rtt}ms")

    print(f"\nPing statistics for {destination}:")
    print(f"Packets: Sent = {count}, Received = {count - lost_count}, Lost = {lost_count} ({lost_count / count * 100}% loss)")
    if count - lost_count > 0:
        print(f"Approximate round trip times in milli-seconds:\n"
              f"Minimum = {min_r