Ping程序设计与实现
时间: 2024-03-20 15:40:51 浏览: 14
Ping程序是用来测试网络连接的工具,它通过向目标主机发送ICMP回显请求和接收ICMP回显应答来检测网络连接是否正常。下面是Ping程序的设计和实现步骤:
1.获取目标主机的IP地址或域名。
2.创建一个原始套接字。
3.设置套接字选项,包括超时时间和TTL值。
4.构造一个ICMP回显请求报文,包括报文头和数据部分。
5.向目标主机发送ICMP回显请求报文。
6.等待接收ICMP回显应答报文。
7.解析接收到的ICMP回显应答报文,判断网络连接是否正常。
8.输出测试结果。
下面是一个简单的Ping程序实现的示例代码:
```python
import socket
import struct
import select
import time
import sys
# 构造ICMP回显请求报文
def create_icmp_packet(id, seq):
header = struct.pack('bbHHh', 8, 0, 0, id, seq)
data = bytes(range(1, 25))
packet = header + data
checksum = calc_checksum(packet)
header = struct.pack('bbHHh', 8, 0, checksum, id, seq)
return header + data
# 计算ICMP校验和
def calc_checksum(packet):
n = len(packet)
m = n % 2
sum = 0
for i in range(0, n - m, 2):
sum += (packet[i] << 8) + packet[i + 1]
if m:
sum += packet[-1] << 8
sum = (sum >> 16) + (sum & 0xffff)
sum += (sum >> 16)
return (~sum) & 0xffff
# 发送ICMP回显请求报文
def send_ping(sockfd, dest_addr, id, seq):
packet = create_icmp_packet(id, seq)
sockfd.sendto(packet, dest_addr)
# 接收ICMP回显应答报文
def recv_ping(sockfd, id, seq, timeout):
start_time = time.time()
while True:
ready = select.select([sockfd], [], [], timeout)
if ready[0]:
packet, addr = sockfd.recvfrom(1024)
icmp_header = packet[20:28]
icmp_type, icmp_code, icmp_checksum, icmp_id, icmp_seq = struct.unpack('bbHHh', icmp_header)
if icmp_type == 0 and icmp_id == id and icmp_seq == seq:
return time.time() - start_time
else:
return -1
# 执行Ping测试
def ping(dest_addr, count=4, timeout=2):
try:
dest_ip = socket.gethostbyname(dest_addr)
except socket.gaierror as e:
print(f"Can't resolve hostname {dest_addr}: {e}")
return
print(f"Pinging {dest_ip} with {count} bytes of data:")
for i in range(count):
sockfd = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.getprotobyname('icmp'))
id = int(time.time() * 1000) & 0xffff
seq = i + 1
send_ping(sockfd, (dest_ip, 0), id, seq)
rtt = recv_ping(sockfd, id, seq, timeout)
sockfd.close()
if rtt < 0:
print(f"Request timed out.")
else:
print(f"Reply from {dest_ip}: time={rtt*1000:.2f}ms")
print(f"Ping statistics for {dest_ip}:")
print(f" Packets: Sent = {count}, Received = {count - timeout}, Lost = {timeout} ({timeout/count*100:.0f}% loss)")
```
在实际应用中,Ping程序还需要支持更多的功能,比如设置TTL值、设置数据包大小、解析ICMP应答报文等,但上述代码已经具备了基本的Ping功能。