Version 3 is current working version

proxy.py

import socket
import threading
import re

def establish_tunnel(remote_socket, target_host, target_port):
    connect_req = f"CONNECT {target_host}:{target_port} HTTP/1.1\r\n\r\n".encode()
    remote_socket.send(connect_req)
    # Read the response. In a production setting, you'd want to actually parse the response.
    response = remote_socket.recv(4096)
    print(f"Received response from corporate proxy: {response.decode()}")

def extract_target_address(data):
    # Try to extract the host and port information from the HTTP header using a regular expression.
    # This version considers the possibility of not having a port in the header and having either domain names or IPs.
    match_with_port = re.search(r'Host: ([a-zA-Z0-9.-]+):([0-9]+)', data.decode(), re.IGNORECASE)
    match_without_port = re.search(r'Host: ([a-zA-Z0-9.-]+)', data.decode(), re.IGNORECASE)
    
    if match_with_port:
        host = match_with_port.group(1)
        port = int(match_with_port.group(2))
        return host, port
    
    elif match_without_port:
        host = match_without_port.group(1)
        return host, None
    
    return None, None

def handle_client(client_socket, proxy_host, proxy_port):
    remote_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    remote_socket.connect((proxy_host, proxy_port))
    
    data = client_socket.recv(4096)
    
    target_host, target_port = extract_target_address(data)
    
    # If target host and port are not specified, fall back to a default proxy (e.g., Squid)
    if target_host is None:
        target_host = "default.proxy.server"  # Replace with your default proxy server
        target_port = 3128  # Replace with your default proxy port

    establish_tunnel(remote_socket, target_host, target_port)
    
    while True:
        if len(data) == 0:
            break
        remote_socket.send(data)
        
        remote_data = remote_socket.recv(4096)
        client_socket.send(remote_data)
        
        data = client_socket.recv(4096)
        
    client_socket.close()
    remote_socket.close()

def main(local_host, local_port, proxy_host, proxy_port):
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server.bind((local_host, local_port))
    server.listen(5)
    print(f"[*] Listening on {local_host}:{local_port}")

    while True:
        client_socket, addr = server.accept()
        print(f"[*] Accepted connection from: {addr[0]}:{addr[1]}")

        # Spin a thread to handle the client
        client_thread = threading.Thread(target=handle_client, args=(client_socket, proxy_host, proxy_port))
        client_thread.start()

if __name__ == "__main__":
    # Local settings (where the proxy will run)
    LOCAL_HOST = "127.0.0.1"
    LOCAL_PORT = 8080
    
    # Corporate Proxy settings
    PROXY_HOST = "corporate.proxy.address"  # Replace with your corporate proxy address
    PROXY_PORT = 8080  # Replace with your corporate proxy port

    main(LOCAL_HOST, LOCAL_PORT, PROXY_HOST, PROXY_PORT)