WIP Mitmproxy script(s) that implement request/response rewriting for unencrypted connections.

client.py

from rewrite import form_rewrite

rewrite_table = {
    "http://www.cs.tut.fi/cgi-bin/run/~jkorpela/echo.cgi": {
        "Comments": "placeholder"
    }
}

def request(flow): # An example for using the form rewriter.
    form_rewrite(flow, rewrite_table)

cookies.py

from mitmproxy import flowfilter

from mitmproxy.addons import stickycookie

sc = stickycookie.StickyCookie()

def start():
    # This is a hack, but it works. Means I don't have to duplicate the entire sticky cookie implementation
    sc.flt = flowfilter.parse("html-kit.com")

def response(flow):
    sc.response(flow)

    # Now that we're done saving the cookies, strip them.
    for name, (value, attrs) in flow.response.cookies.items(multi=True): # taken from
        # FIXME: We now know that Cookie.py screws up some cookies with
        # valid RFC 822/1123 datetime specifications for expiry. Sigh.
        dom_port_path = stickycookie.ckey(attrs, flow)

        if stickycookie.domain_match(flow.request.host, dom_port_path[0]):
            flow.response.cookies.pop(name) # TODO: Is there a better way to do this?

def request(flow):
    sc.request(flow)

# Using http://www.html-kit.com/tools/cookietester/ as a test for cookie stripping.

rewrite.py

import json
from collections.abc import Mapping

def _rewrite(obj, rewrite):
    for name in rewrite:
        if isinstance(rewrite[name], Mapping) and name in obj:
            _rewrite(obj[name], rewrite[name])
            continue
        obj[name] = rewrite[name]
    return obj

def form_rewrite(flow, rewrite):
    if flow.request.urlencoded_form:
        if flow.request.pretty_url not in rewrite:
            return
        flow.request.urlencoded_form = _rewrite(flow.request.urlencoded_form, rewrite[flow.request.pretty_url])
# Using https://www.cs.tut.fi/~jkorpela/forms/testing.html as a test for form rewriting.

def json_rewrite(content, rewrite):
    try:
        obj = json.loads(content)
        obj = _rewrite(obj, rewrite)
        content = json.dumps(obj)
    except ValueError:
        return # If it's not json, do nothing.

server.py

from rewrite import form_rewrite
import cookies

def start():
    cookies.start()

def request(flow):
    cookies.request(flow)

    val = "" # Another example for using the form rewriter.
    if "Comments" in flow.request.urlencoded_form:
        val = flow.request.urlencoded_form["Comments"]
    rewrite_table = {
        "https://www.cs.tut.fi/cgi-bin/run/~jkorpela/echo.cgi": {
            "Comments": "This is a very insightful comment that replaced the following: {}"
            .format(val)
        }
    }
    form_rewrite(flow, rewrite_table)

def response(flow):
    cookies.response(flow)