All of mitmproxy's basic functionality is exposed through the libmproxy library. The example below shows a simple implementation of the "sticky cookie" functionality included in the interactive mitmproxy program. Traffic is monitored for cookie and set-cookie headers, and requests are rewritten to include a previously seen cookie if they don't already have one. In effect, this lets you log in to a site using your browser, and then make subsequent requests using a tool like curl, which will then seem to be part of the authenticated session.

#!/usr/bin/env python
"""
This example builds on mitmproxy's base proxying infrastructure to
implement functionality similar to the "sticky cookies" option. This is at
a lower level than the Flow mechanism, so we're dealing directly with
request and response objects.
"""
from libmproxy import controller, proxy
import os

class StickyMaster(controller.Master):
    def __init__(self, server):
        controller.Master.__init__(self, server)
        self.stickyhosts = {}

    def run(self):
        try:
            return controller.Master.run(self)
        except KeyboardInterrupt:
            self.shutdown()

    def handle_request(self, msg):
        hid = (msg.host, msg.port)
        if msg.headers["cookie"]:
            self.stickyhosts[hid] = msg.headers["cookie"]
        elif hid in self.stickyhosts:
            msg.headers["cookie"] = self.stickyhosts[hid]
        msg.reply()

    def handle_response(self, msg):
        hid = (msg.request.host, msg.request.port)
        if msg.headers["set-cookie"]:
            self.stickyhosts[hid] = msg.headers["set-cookie"]
        msg.reply()


config = proxy.ProxyConfig(
    cacert = os.path.expanduser("~/.mitmproxy/mitmproxy-ca.pem")
)
server = proxy.ProxyServer(config, 8080)
m = StickyMaster(server)
m.run()
(examples/stickycookies)