How to retain cookies for xmlrpc.client in Python 3?

Question

The default Python xmlrpc.client.Transport (can be used with xmlrpc.client.ServerProxy) does not retain cookies, which are sometimes needed for cookie based logins.

For example, the following proxy, when used with the TapaTalk API (for which the login method uses cookies for authentication), will give a permission error when trying to modify posts.

proxy = xmlrpc.client.ServerProxy(URL, xmlrpc.client.Transport())

There are some solutions for Python 2 on the net, but they aren't compatible with Python 3.

How can I use a Transport that retains cookies?

Answer 1

This is a simple Transport subclass that will retain all cookies:

class CookiesTransport(xmlrpc.client.Transport):
"""A Transport subclass that retains cookies over its lifetime."""

    def __init__(self):
        super().__init__()
        self._cookies = []

    def send_headers(self, connection, headers):
        if self._cookies:
            connection.putheader("Cookie", "; ".join(self._cookies))
        super().send_headers(connection, headers)

    def parse_response(self, response):
        for header in response.msg.get_all("Set-Cookie"):
            cookie = header.split(";", 1)[0]
            self._cookies.append(cookie)
        return super().parse_response(response)

Usage:

proxy = xmlrpc.client.ServerProxy(URL, CookiesTransport())

Since xmlrpc.client in Python 3 has better suited hooks for this, it's much simpler than an equivalent Python 2 version.