实现ping程序

好的，实现Ping程序需要使用ICMP协议。以下是一个简单的Python实现，可以用于Linux和Windows系统：

import os
import sys
import struct
import socket
import select
import time

# 计算校验和
def checksum(data):
    n = len(data)
    m = n % 2
    sum = 0
    for i in range(0, n - m, 2):
        sum += (data[i]) + ((data[i+1]) << 8)
    if m:
        sum += (data[-1])
    sum = (sum >> 16) + (sum & 0xffff)
    sum += (sum >> 16)
    result = (~sum) & 0xffff
    result = result >> 8 | (result << 8 & 0xff00)
    return result

# 发送ICMP请求报文
def send_ping(sock, dest_addr, pid, seq):
    # 构造ICMP请求报文
    icmp_type = 8 # ICMP Echo Request
    icmp_code = 0
    icmp_checksum = 0
    icmp_id = pid & 0xffff
    icmp_seq = seq & 0xffff
    icmp_data = b'Hello, World!'
    icmp_checksum = checksum(struct.pack('!BBHHH', icmp_type, icmp_code, icmp_checksum, icmp_id, icmp_seq) + icmp_data)
    icmp_packet = struct.pack('!BBHHH', icmp_type, icmp_code, icmp_checksum, icmp_id, icmp_seq) + icmp_data
    # 发送ICMP请求报文
    sock.sendto(icmp_packet, (dest_addr, 0))

# 接收ICMP响应报文
def receive_ping(sock, pid, seq, timeout):
    time_left = timeout
    while True:
        # 设置超时时间
        start_time = time.time()
        ready = select.select([sock], [], [], time_left)
        elapsed = (time.time() - start_time)
        if not ready[0]:
            return None, None, None, None, None
        # 接收到ICMP响应报文
        pkt, addr = sock.recvfrom(1024)
        icmp_header = pkt[20:28]
        icmp_type, icmp_code, icmp_checksum, icmp_id, icmp_seq = struct.unpack('!BBHHH', icmp_header)
        # 判断是否为ICMP响应报文
        if icmp_type == 0 and icmp_id == pid and icmp_seq == seq:
            icmp_data = pkt[28:]
            return addr[0], icmp_type, icmp_code, icmp_checksum, icmp_data
        # 更新超时时间
        time_left -= elapsed
        if time_left <= 0:
            return None, None, None, None, None

# Ping指定主机
def ping(dest_addr, count, timeout):
    # 创建原始套接字
    sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_ICMP)
    pid = os.getpid() & 0xffff
    for i in range(count):
        seq = i + 1
        # 发送ICMP请求报文
        send_ping(sock, dest_addr, pid, seq)
        # 接收ICMP响应报文
        addr, icmp_type, icmp_code, icmp_checksum, icmp_data = receive_ping(sock, pid, seq, timeout)
        # 输出结果
        if addr is not None:
            print('Reply from {}: icmp_seq={}, time={}ms'.format(addr, seq, round(icmp_checksum * 1000 / timeout)))
        else:
            print('Request timed out.')
    sock.close()

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print('Usage: python ping.py <host> [count] [timeout]')
    else:
        dest_addr = sys.argv[1]
        count = int(sys.argv[2]) if len(sys.argv) > 2 else 4
        timeout = int(sys.argv[3]) if len(sys.argv) > 3 else 1000
        ping(dest_addr, count, timeout)

您可以将以上代码保存为ping.py，并在终端中运行以下命令来Ping指定主机：

python ping.py <host> [count] [timeout]

其中，<host>为目标主机的IP地址或域名，[count]为Ping包数量，默认为4，[timeout]为超时时间（毫秒），默认为1000。