如何开发带有用户名和密码验证的HTTP代理服务器？

下面是一个Python实现的HTTP代理服务器，它支持基本的用户名和密码验证：

import socket
import threading
import base64

def handle_client(client_socket):
    request_data = client_socket.recv(1024)
    if not request_data:
        client_socket.close()
        return
    
    first_line = request_data.split(b'\n')[0]
    url = first_line.split(b' ')[1]
    if b'://' not in url:
        url = b'http://' + url
    host = url.split(b'://')[1].split(b'/')[0]
    
    # Username and password authentication
    auth = False
    headers = request_data.split(b'\n')[1:]
    for header in headers:
        if b'Proxy-Authorization' in header:
            auth_header = header.split(b' ')[2]
            auth_header_decoded = base64.b64decode(auth_header).decode('utf-8')
            username, password = auth_header_decoded.split(':')
            if username == 'admin' and password == 'password':
                auth = True
                break

    if not auth:
        error_message = b'HTTP/1.1 407 Proxy Authentication Required\r\n'
        error_message += b'Proxy-Authenticate: Basic realm="MyProxy"\r\n'
        error_message += b'Content-Length: 20\r\n\r\n'
        error_message += b'Authentication Error'
        client_socket.send(error_message)
        client_socket.close()
        return
    
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.settimeout(3)
    server_socket.connect((host, 80))
    server_socket.send(request_data)
    
    while True:
        response_data = server_socket.recv(4096)
        if not response_data:
            break
        client_socket.send(response_data)
    
    client_socket.close()
    server_socket.close()

def start_server(ip, port):
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server_socket.bind((ip, port))
    server_socket.listen(5)
    print('Proxy server listening on %s:%d' % (ip, port))

    while True:
        client_socket, _ = server_socket.accept()
        client_thread = threading.Thread(target=handle_client, args=(client_socket,))
        client_thread.start()

start_server('127.0.0.1', 8080)

此代码首先解析HTTP请求以确定目标主机和端口。然后，它检查传入请求的Proxy-Authorization头，如果该头基本身份验证通过，则转