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最近写服务器，解析请求报文时很麻烦，用的是正则表达式，很累，有人可以告诉我有什么好的方法吗？

代码：

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import sys
import socket
import re
import datetime
from os.path import getctime
from multiprocessing import Process


now = lambda:datetime.datetime.now().strftime("[%H-%M-%S]")
# 设置静态文件根目录
H喵L_ROOT_DIR = "."
LINES_SEP = bytes("\r\n", "utf-8")


class HTTPServer(object):
    def __init__(self):
        print(now(),"创建服务器")
        self.server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

    def start(self):
        print(now(),"开始运行服务器,按 Ctrl+C 退出")
        try:
            self.server_socket.listen(128)
            while True:
                client_socket, client_address = self.server_socket.accept()
                print(now(),"连接 %s:%s" % client_address)
                handle_client_process = Process(target=self.handle_client, args=(client_socket,))
                handle_client_process.start()
                client_socket.close()
        except KeyboardInterrupt:
            print(now(),"服务器已停止运行")

    def handle_client(self, client_socket):
        """
        处理客户端请求
        """
        # 获取客户端请求数据
        request_data = client_socket.recv(4096)
        request_lines = request_data.splitlines()
        # 解析请求报文
        if len(request_lines) == 0:
            client_socket.close()
            print(now(),"Error:","空请求")
            return "error"
        request_start_line = request_lines[0]
        # 提取用户请求的文件名
        file_name = re.match(r"\w+ +(/[^ ]*) ", request_start_line.decode("utf-8")).group(1)

        if "/" == file_name:
            file_name = "/index.html"
        # 打开文件，读取内容
        
        try:
            file = open(H喵L_ROOT_DIR + file_name, "rb")
        except IOError:
            with open(H喵L_ROOT_DIR + "/error/404.html","rb") as file:
                file_data = file.read()
            response_start_line = "HTTP/1.1 404 Not Found\r\n".encode("utf-8")
            response_headers = "Server: Python\r\n".encode("utf-8")
            response_body = file_data
            print(now(),"HTTP/1.1 404 Not Found " + file_name)
        else:
            file_data = file.read()
            file.close()

            # 构造响应数据
            response_start_line = "HTTP/1.1 200 OK\r\n".encode("utf-8")
            response_headers = "Server: Python \r\n".encode("utf-8")
            response_body = file_data
            print(now(),"HTTP/1.1 200 OK " + file_name)

        response = response_start_line + response_headers + LINES_SEP + response_body

        # 向客户端返回响应数据
        client_socket.send(response)

        # 关闭客户端连接
        client_socket.close()

    def bind(self, port):
        print(now(),"监听 {} 端口".format(port))
        self.server_socket.bind(("", port))


def main():
    http_server = HTTPServer()
    http_server.bind(80)
    http_server.start()


if __name__ == "__main__":
    main()