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Python--网络编程

news 来源：原创 2025/5/15 23:45:19

3. 网络编程与Socket

3.1 Socket基础

创建Socket

import socket

# TCP Socket
tcp_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# UDP Socket
udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

服务器端函数

函数	描述
bind((host, port))	绑定地址和端口
listen(backlog)	开始监听传入连接
accept()	接受连接，返回新Socket和客户端地址

客户端函数

函数	描述
connect((host, port))	连接到服务器
send(data)	发送数据（TCP）
sendto(data, address)	发送数据（UDP）

3.2 高级Socket功能

超时与异常处理

import socket

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(5)  # 设置超时为5秒
try:
    s.connect(("example.com", 80))
except socket.timeout:
    print("连接超时！")
except socket.error as e:
    print(f"连接错误: {e}")
finally:
    s.close()

多线程Socket服务器

import socket
import threading

def handle_client(conn, addr):
    print(f"客户端 {addr} 已连接")
    data = conn.recv(1024)
    conn.send(b"Server: Received")
    conn.close()

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(("0.0.0.0", 8080))
server.listen(5)

while True:
    conn, addr = server.accept()
    thread = threading.Thread(target=handle_client, args=(conn, addr))
    thread.start()

实现简单HTTP请求

# 发送HTTP GET请求
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("example.com", 80))
s.send(b"GET / HTTP/1.1\r\nHost: example.com\r\n\r\n")
response = s.recv(4096)
print(response.decode())
s.close()

3.3 TCP通信示例

服务器端：

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind(("0.0.0.0", 8080))
server_socket.listen(5)
conn, addr = server_socket.accept()
data = conn.recv(1024)
conn.send(b"Received")
conn.close()

客户端：

client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect(("127.0.0.1", 8080))
client_socket.send(b"Hello Server")
response = client_socket.recv(1024)
client_socket.close()

3.4 UDP通信示例

服务器端：

udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_socket.bind(("0.0.0.0", 9090))
data, addr = udp_socket.recvfrom(1024)
udp_socket.sendto(b"ACK", addr)

客户端：

udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_socket.sendto(b"Hello", ("127.0.0.1", 9090))
response, addr = udp_socket.recvfrom(1024)

3.5 端口扫描与主机探测

使用 python-nmap 库进行端口扫描：

import nmap

scanner = nmap.PortScanner()
scanner.scan("192.168.1.1", "1-1024", "-sS")  # SYN扫描
print(scanner.all_hosts())
print(scanner["192.168.1.1"].all_tcp())

4. 工具与资源

正则表达式在线测试工具：https://regex101.com
网络调试工具：Wireshark、Postman、tcpdump

Python库：

python-nmap：pip install python-nmap
requests：HTTP请求库
scapy：构造和解析网络数据包。
```
pip install scapy
```

asyncio：实现异步网络编程。

import asyncio

async def tcp_echo_client(message):
    reader, writer = await asyncio.open_connection("127.0.0.1", 8888)
    writer.write(message.encode())
    data = await reader.read(100)
    print(f"Received: {data.decode()}")
    writer.close()

asyncio.run(tcp_echo_client("Hello Server"))