TCP服务器和客户端的创建（socket/socketserver）

1 本文记录针对python网络编程学习过程中的socket部分进行记录与总结，内容仅仅涉及最粗浅的部分，日后或许会进行更新与扩展。
2 本文涉及的socket数据传输均使用bytes类型，因此在python3环境下，需要特别注意字符串的编码与解码。

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1 socket模块

A pair (host, port) is used for the AF_INET address family, where host is a string representing either a hostname in Internet domain notation like ‘daring.cwi.nl’ or an IPv4 address like ‘100.50.200.5’, and port is an integer.
For IPv4 addresses, two special forms are accepted instead of a host address: the empty string represents INADDR_ANY, and the string ‘’ represents INADDR_BROADCAST. This behavior is not compatible with IPv6, therefore, you may want to avoid these if you intend to support IPv6 with your Python programs.

• 创建socket对象，socket.socket(family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None)
• 根据官方文档说明，socket接受两种特殊形式的IPv4的地址。空白地址代表INADDR_ANY，允许任意地址接入；而字符串’’则代表INADDR_BROADCAST。

1.1 创建TCP服务器 - socket.socket()

from socket import *
from time import ctime

HOST = ''               # 允许任意host接入
PORT = 21567
BUFSIZ = 1024
ADDR = (HOST, PORT)

tcpSerSock = socket(AF_INET, SOCK_STREAM)
tcpSerSock.bind(ADDR)   # 绑定地址
tcpSerSock.listen(5)    # 最多同时监听数量上限为5

while True:
    print('waiting for connection...')
    # 接受客户端请求之前保持阻塞，连接后获取客户端socket及其地址
    tcpCliSock, addr = tcpSerSock.accept() 
    # 打印请求此次服务的客户端的地址 
    print('...connection from: {}'.format(addr))
    while True:
        # 通过客户socket获取客户端信息(bytes类型)，并解码为字符串类型
        data = tcpCliSock.recv(BUFSIZ).decode('utf8')
        if not data:
            break
        # 处理字符串并重新编码为bytes类型，调用send()方法发送回客户端
        tcpCliSock.send('[{}] {}'.format(ctime(), data).encode('utf8'))
    # 关闭客户端
    tcpCliSock.close()
# 关闭服务器
tcpCliSock.close()

1.2 创建TCP客户端 - socket.socket()

from socket import *

HOST = 'localhost'              # 指定客户端访问host
PORT = 21567
BUFSIZ = 1024
ADDR = (HOST, PORT)

tcpCliSock = socket(AF_INET, SOCK_STREAM)
tcpCliSock.connect(ADDR)        # 连接地址

while True:
    # 用户输入数据(str类型)
    data = input('> ')
    if not data:
        break
    # 将数据进行编码，再通过send()方法发送给之前绑定的地址服务器
    tcpCliSock.send(data.encode('utf8'))
    # 接收服务器返回的数据(bytes类型)，解码为字符串类型
    data = tcpCliSock.recv(BUFSIZ).decode('utf8')
    if not data:
        break
    # 打印字符串
    print(data)
# 关闭客户端，断开连接
tcpCliSock.close()

1.3 终端交互

本地连接交互

远程连接交互

• 更改client的host为远程主机地址
  

2 socketserver模块

• 创建TCPServer对象，class socketserver.TCPServer(server_address, RequestHandlerClass, bind_and_activate=True)

• 继承基类RequestHandlerClass，重写自己的MyRequestsHandler

  class socketserver.BaseRequestHandler

  This is the superclass of all request handler objects. It defines the interface, given below. A concrete request handler subclass must define a new handle() method, and can override any of the other methods. A new instance of the subclass is created for each request.
  handle()
  This function must do all the work required to service a request. The default implementation does nothing. Several instance attributes are available to it; the request is available as self.request; the client address as self.client_address; and the server instance as self.server, in case it needs access to per-server information.
  The type of self.request is different for datagram or stream services. For stream services, self.request is a socket object; for datagram services, self.request is a pair of string and socket.

2.1 创建TCP服务器 - socketserver.TCPServer()

from socketserver import TCPServer as TCP
from socketserver import StreamRequestHandler as SRH
from time import ctime

HOST = ''
PORT = 21567
ADDR = (HOST, PORT)

# 重写自己的RequestHandlerClass类
class MyRequestsHandler(SRH):
    # override处理数据的方法，基类默认该方法为空
    def handle(self):
        # 打印客户端的地址信息，该信息被储存在self.client_address中
        print('connected from: {}'.format(self.client_address))
        # self.rfile.readline()读取客户端发送的信息(bytes类型)，并解码为字符串类型
        # 写入字符串类型信息，编码为bytes(此处没有send()方法)
        self.wfile.write('[{}] {}'.format(ctime(), self.rfile.readline().decode('utf8')).encode('utf8'))

# 构造socketserver.TCPServer类，传入地址和handler方法参数
tcpServ = TCP(ADDR, MyRequestsHandler)
print('waiting for connection...')
# 开启该服务，直至中断
tcpServ.serve_forever()

2.2 创建TCP客户端 - socket.socket()

from socket import *

HOST = 'localhost'
PORT = 21567
BUFSIZ = 1024
ADDR = (HOST, PORT)

while True:
    tcpCliSock = socket(AF_INET, SOCK_STREAM)
    tcpCliSock.connect(ADDR)
    data = input('> ')
    if not data:
        break
    # 以行终止符作为结尾，发送字符串信息并编码
    tcpCliSock.send('{}\r\n'.format(data).encode('utf8'))
    # 接收服务端传回的数据并解码
    data = tcpCliSock.recv(BUFSIZ).decode('utf8')
    if not data:
        break
    print(data.strip())
    tcpCliSock.close()

2.3 终端交互

本地连接交互

远程连接交互

• 更改client的host为远程主机地址
  

参考资料

Python核心编程（第3版）
官方文档 – socket模块
官方文档 – socketserver模块