useragent.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""Get User-Agent header from default browser"""

import webbrowser
import socket


def user_agent():
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server.bind(("127.0.0.1", 6414))
    server.listen(1)

    webbrowser.open("http://127.0.0.1:6414/user-agent")

    client = server.accept()[0]
    server.close()

    for line in client.recv(1024).split(b"\n"):
        key, _, value = line.partition(b":")
        if key.strip().lower() == b"user-agent":
            useragent = value.strip()
            break
    else:
        useragent = b""

    client.send(b"HTTP/1.1 200 OK\r\n\r\n" + useragent)
    client.close()

    return useragent.decode()


if __name__ == "__main__":
    print(user_agent())