mitmproxy/libmproxy/flow.py

"""
    This module provides more sophisticated flow tracking. These match requests
    with their responses, and provide filtering and interception facilities.
"""
import base64
import hashlib, Cookie, cookielib, re, threading
import os
import flask
import requests
import tnetstring, filt, script
from netlib import odict, wsgi
from .proxy import ClientConnection, ServerConnection  # FIXME: remove circular dependency
import controller, version, protocol
import app
from .protocol import KILL
from .protocol.http import HTTPResponse, CONTENT_MISSING
from .proxy import RequestReplayThread

ODict = odict.ODict
ODictCaseless = odict.ODictCaseless


class AppRegistry:
    def __init__(self):
        self.apps = {}

    def add(self, app, domain, port):
        """
            Add a WSGI app to the registry, to be served for requests to the
            specified domain, on the specified port.
        """
        self.apps[(domain, port)] = wsgi.WSGIAdaptor(app, domain, port, version.NAMEVERSION)

    def get(self, request):
        """
            Returns an WSGIAdaptor instance if request matches an app, or None.
        """
        if (request.get_host(), request.get_port()) in self.apps:
            return self.apps[(request.get_host(), request.get_port())]
        if "host" in request.headers:
            host = request.headers["host"][0]
            return self.apps.get((host, request.get_port()), None)


class ReplaceHooks:
    def __init__(self):
        self.lst = []

    def set(self, r):
        self.clear()
        for i in r:
            self.add(*i)

    def add(self, fpatt, rex, s):
        """
            add a replacement hook.

            fpatt: a string specifying a filter pattern.
            rex: a regular expression.
            s: the replacement string

            returns true if hook was added, false if the pattern could not be
            parsed.
        """
        cpatt = filt.parse(fpatt)
        if not cpatt:
            return False
        try:
            re.compile(rex)
        except re.error:
            return False
        self.lst.append((fpatt, rex, s, cpatt))
        return True

    def get_specs(self):
        """
            Retrieve the hook specifcations. Returns a list of (fpatt, rex, s) tuples.
        """
        return [i[:3] for i in self.lst]

    def count(self):
        return len(self.lst)

    def run(self, f):
        for _, rex, s, cpatt in self.lst:
            if cpatt(f):
                if f.response:
                    f.response.replace(rex, s)
                else:
                    f.request.replace(rex, s)

    def clear(self):
        self.lst = []


class SetHeaders:
    def __init__(self):
        self.lst = []

    def set(self, r):
        self.clear()
        for i in r:
            self.add(*i)

    def add(self, fpatt, header, value):
        """
            Add a set header hook.

            fpatt: String specifying a filter pattern.
            header: Header name.
            value: Header value string

            Returns True if hook was added, False if the pattern could not be
            parsed.
        """
        cpatt = filt.parse(fpatt)
        if not cpatt:
            return False
        self.lst.append((fpatt, header, value, cpatt))
        return True

    def get_specs(self):
        """
            Retrieve the hook specifcations. Returns a list of (fpatt, rex, s) tuples.
        """
        return [i[:3] for i in self.lst]

    def count(self):
        return len(self.lst)

    def clear(self):
        self.lst = []

    def run(self, f):
        for _, header, value, cpatt in self.lst:
            if cpatt(f):
                if f.response:
                    del f.response.headers[header]
                else:
                    del f.request.headers[header]
        for _, header, value, cpatt in self.lst:
            if cpatt(f):
                if f.response:
                    f.response.headers.add(header, value)
                else:
                    f.request.headers.add(header, value)


class ClientPlaybackState:
    def __init__(self, flows, exit):
        self.flows, self.exit = flows, exit
        self.current = None

    def count(self):
        return len(self.flows)

    def done(self):
        if len(self.flows) == 0 and not self.current:
            return True
        return False

    def clear(self, flow):
        """
           A request has returned in some way - if this is the one we're
           servicing, go to the next flow.
        """
        if flow is self.current:
            self.current = None

    def tick(self, master, testing=False):
        """
            testing: Disables actual replay for testing.
        """
        if self.flows and not self.current:
            n = self.flows.pop(0)
            n.request.reply = controller.DummyReply()
            n.client_conn = None
            self.current = master.handle_request(n.request)
            if not testing and not self.current.response:
                master.replay_request(self.current) # pragma: no cover
            elif self.current.response:
                master.handle_response(self.current.response)


class ServerPlaybackState:
    def __init__(self, headers, flows, exit, nopop):
        """
            headers: Case-insensitive list of request headers that should be
            included in request-response matching.
        """
        self.headers, self.exit, self.nopop = headers, exit, nopop
        self.fmap = {}
        for i in flows:
            if i.response:
                l = self.fmap.setdefault(self._hash(i), [])
                l.append(i)

    def count(self):
        return sum(len(i) for i in self.fmap.values())

    def _hash(self, flow):
        """
            Calculates a loose hash of the flow request.
        """
        r = flow.request
        key = [
            str(r.host),
            str(r.port),
            str(r.scheme),
            str(r.method),
            str(r.path),
            str(r.content),
        ]
        if self.headers:
            hdrs = []
            for i in self.headers:
                v = r.headers[i]
                # Slightly subtle: we need to convert everything to strings
                # to prevent a mismatch between unicode/non-unicode.
                v = [str(x) for x in v]
                hdrs.append((i, v))
            key.append(repr(hdrs))
        return hashlib.sha256(repr(key)).digest()

    def next_flow(self, request):
        """
            Returns the next flow object, or None if no matching flow was
            found.
        """
        l = self.fmap.get(self._hash(request))
        if not l:
            return None

        if self.nopop:
            return l[0]
        else:
            return l.pop(0)


class StickyCookieState:
    def __init__(self, flt):
        """
            flt: Compiled filter.
        """
        self.jar = {}
        self.flt = flt

    def ckey(self, m, f):
        """
            Returns a (domain, port, path) tuple.
        """
        return (
            m["domain"] or f.request.get_host(),
            f.request.get_port(),
            m["path"] or "/"
        )

    def domain_match(self, a, b):
        if cookielib.domain_match(a, b):
            return True
        elif cookielib.domain_match(a, b.strip(".")):
            return True
        return False

    def handle_response(self, f):
        for i in f.response.headers["set-cookie"]:
            # FIXME: We now know that Cookie.py screws up some cookies with
            # valid RFC 822/1123 datetime specifications for expiry. Sigh.
            c = Cookie.SimpleCookie(str(i))
            m = c.values()[0]
            k = self.ckey(m, f)
            if self.domain_match(f.request.get_host(), k[0]):
                self.jar[self.ckey(m, f)] = m

    def handle_request(self, f):
        l = []
        if f.match(self.flt):
            for i in self.jar.keys():
                match = [
                    self.domain_match(f.request.get_host(), i[0]),
                    f.request.get_port() == i[1],
                    f.request.path.startswith(i[2])
                ]
                if all(match):
                    l.append(self.jar[i].output(header="").strip())
        if l:
            f.request.stickycookie = True
            f.request.headers["cookie"] = l


class StickyAuthState:
    def __init__(self, flt):
        """
            flt: Compiled filter.
        """
        self.flt = flt
        self.hosts = {}

    def handle_request(self, f):
        host = f.request.get_host()
        if "authorization" in f.request.headers:
            self.hosts[host] = f.request.headers["authorization"]
        elif f.match(self.flt):
            if host in self.hosts:
                f.request.headers["authorization"] = self.hosts[host]


class State(object):
    def __init__(self):
        self._flow_list = []
        self.view = []

        # These are compiled filt expressions:
        self._limit = None
        self.intercept = None
        self._limit_txt = None

    @property
    def limit_txt(self):
        return self._limit_txt

    def flow_count(self):
        return len(self._flow_list)

    def index(self, f):
        return self._flow_list.index(f)

    def active_flow_count(self):
        c = 0
        for i in self._flow_list:
            if not i.response and not i.error:
                c += 1
        return c

    def add_request(self, req):
        """
            Add a request to the state. Returns the matching flow.
        """
        f = req.flow
        self._flow_list.append(f)
        if f.match(self._limit):
            self.view.append(f)
        return f

    def add_response(self, resp):
        """
            Add a response to the state. Returns the matching flow.
        """
        f = resp.flow
        if not f:
            return False
        if f.match(self._limit) and not f in self.view:
            self.view.append(f)
        return f

    def add_error(self, err):
        """
            Add an error response to the state. Returns the matching flow, or
            None if there isn't one.
        """
        f = err.flow
        if not f:
            return None
        if f.match(self._limit) and not f in self.view:
            self.view.append(f)
        return f

    def load_flows(self, flows):
        self._flow_list.extend(flows)
        self.recalculate_view()

    def set_limit(self, txt):
        if txt:
            f = filt.parse(txt)
            if not f:
                return "Invalid filter expression."
            self._limit = f
            self._limit_txt = txt
        else:
            self._limit = None
            self._limit_txt = None
        self.recalculate_view()

    def set_intercept(self, txt):
        if txt:
            f = filt.parse(txt)
            if not f:
                return "Invalid filter expression."
            self.intercept = f
            self.intercept_txt = txt
        else:
            self.intercept = None
            self.intercept_txt = None

    def recalculate_view(self):
        if self._limit:
            self.view = [i for i in self._flow_list if i.match(self._limit)]
        else:
            self.view = self._flow_list[:]

    def delete_flow(self, f):
        self._flow_list.remove(f)
        if f in self.view:
            self.view.remove(f)
        return True

    def clear(self):
        for i in self._flow_list[:]:
            self.delete_flow(i)

    def accept_all(self):
        for i in self._flow_list[:]:
            i.accept_intercept()

    def revert(self, f):
        f.revert()

    def killall(self, master):
        for i in self._flow_list:
            i.kill(master)


class FlowMaster(controller.Master):
    def __init__(self, server, state):
        controller.Master.__init__(self, server)
        self.state = state
        self.server_playback = None
        self.client_playback = None
        self.kill_nonreplay = False
        self.scripts = []
        self.pause_scripts = False

        self.stickycookie_state = False
        self.stickycookie_txt = None

        self.stickyauth_state = False
        self.stickyauth_txt = None

        self.anticache = False
        self.anticomp = False
        self.refresh_server_playback = False
        self.replacehooks = ReplaceHooks()
        self.setheaders = SetHeaders()

        self.stream = None
        self.apps = AppRegistry()

    def start_app(self, host, port, external):
        if not external:
            self.apps.add(
                app.mapp,
                host,
                port
            )
        else:
            @app.mapp.before_request
            def patch_environ(*args, **kwargs):
                flask.request.environ["mitmproxy.master"] = self

            # the only absurd way to shut down a flask/werkzeug server.
            # http://flask.pocoo.org/snippets/67/
            shutdown_secret = base64.b32encode(os.urandom(30))

            @app.mapp.route('/shutdown/<secret>')
            def shutdown(secret):
                if secret == shutdown_secret:
                    flask.request.environ.get('werkzeug.server.shutdown')()

            # Workaround: Monkey-patch shutdown function to stop the app.
            # Improve this when we switch werkzeugs http server for something useful.
            _shutdown = self.shutdown
            def _shutdownwrap():
                _shutdown()
                requests.get("http://%s:%s/shutdown/%s" % (host, port, shutdown_secret))
            self.shutdown = _shutdownwrap

            threading.Thread(target=app.mapp.run, kwargs={
                "use_reloader": False,
                "host": host,
                "port": port}).start()

    def add_event(self, e, level="info"):
        """
            level: info, error
        """
        pass

    def unload_scripts(self):
        for s in self.scripts[:]:
            s.unload()
            self.scripts.remove(s)

    def load_script(self, command):
        """
            Loads a script. Returns an error description if something went
            wrong.
        """
        try:
            s = script.Script(command, self)
        except script.ScriptError, v:
            return v.args[0]
        self.scripts.append(s)

    def run_single_script_hook(self, script, name, *args, **kwargs):
        if script and not self.pause_scripts:
            ret = script.run(name, *args, **kwargs)
            if not ret[0] and ret[1]:
                e = "Script error:\n" + ret[1][1]
                self.add_event(e, "error")

    def run_script_hook(self, name, *args, **kwargs):
        for script in self.scripts:
            self.run_single_script_hook(script, name, *args, **kwargs)

    def set_stickycookie(self, txt):
        if txt:
            flt = filt.parse(txt)
            if not flt:
                return "Invalid filter expression."
            self.stickycookie_state = StickyCookieState(flt)
            self.stickycookie_txt = txt
        else:
            self.stickycookie_state = None
            self.stickycookie_txt = None

    def set_stickyauth(self, txt):
        if txt:
            flt = filt.parse(txt)
            if not flt:
                return "Invalid filter expression."
            self.stickyauth_state = StickyAuthState(flt)
            self.stickyauth_txt = txt
        else:
            self.stickyauth_state = None
            self.stickyauth_txt = None

    def start_client_playback(self, flows, exit):
        """
            flows: List of flows.
        """
        self.client_playback = ClientPlaybackState(flows, exit)

    def stop_client_playback(self):
        self.client_playback = None

    def start_server_playback(self, flows, kill, headers, exit, nopop):
        """
            flows: List of flows.
            kill: Boolean, should we kill requests not part of the replay?
        """
        self.server_playback = ServerPlaybackState(headers, flows, exit, nopop)
        self.kill_nonreplay = kill

    def stop_server_playback(self):
        if self.server_playback.exit:
            self.shutdown()
        self.server_playback = None

    def do_server_playback(self, flow):
        """
            This method should be called by child classes in the handle_request
            handler. Returns True if playback has taken place, None if not.
        """
        if self.server_playback:
            rflow = self.server_playback.next_flow(flow)
            if not rflow:
                return None
            response = HTTPResponse._from_state(rflow.response._get_state())
            response.is_replay = True
            if self.refresh_server_playback:
                response.refresh()
            flow.request.reply(response)
            if self.server_playback.count() == 0:
                self.stop_server_playback()
            return True
        return None

    def tick(self, q):
        if self.client_playback:
            e = [
                self.client_playback.done(),
                self.client_playback.exit,
                self.state.active_flow_count() == 0
            ]
            if all(e):
                self.shutdown()
            self.client_playback.tick(self)

        return controller.Master.tick(self, q)

    def duplicate_flow(self, f):
        return self.load_flow(f.copy())

    def load_flow(self, f):
        """
            Loads a flow, and returns a new flow object.
        """
        if f.request:
            f.request.reply = controller.DummyReply()
            fr = self.handle_request(f.request)
        if f.response:
            f.response.reply = controller.DummyReply()
            self.handle_response(f.response)
        if f.error:
            f.error.reply = controller.DummyReply()
            self.handle_error(f.error)
        return fr

    def load_flows(self, fr):
        """
            Load flows from a FlowReader object.
        """
        for i in fr.stream():
            self.load_flow(i)

    def process_new_request(self, f):
        if self.stickycookie_state:
            self.stickycookie_state.handle_request(f)
        if self.stickyauth_state:
            self.stickyauth_state.handle_request(f)

        if self.anticache:
            f.request.anticache()
        if self.anticomp:
            f.request.anticomp()

        if self.server_playback:
            pb = self.do_server_playback(f)
            if not pb:
                if self.kill_nonreplay:
                    f.kill(self)
                else:
                    f.request.reply()

    def process_new_response(self, f):
        if self.stickycookie_state:
            self.stickycookie_state.handle_response(f)

    def replay_request(self, f, block=False):
        """
            Returns None if successful, or error message if not.
        """
        if f.intercepting:
            return "Can't replay while intercepting..."
        if f.request.content == CONTENT_MISSING:
            return "Can't replay request with missing content..."
        if f.request:
            f.request.is_replay = True
            if f.request.content:
                f.request.headers["Content-Length"] = [str(len(f.request.content))]
            f.response = None
            f.error = None
            self.process_new_request(f)
            rt = RequestReplayThread(
                    self.server.config,
                    f,
                    self.masterq,
                )
            rt.start() # pragma: no cover
            if block:
                rt.join()

    def handle_clientconnect(self, cc):
        self.run_script_hook("clientconnect", cc)
        cc.reply()

    def handle_clientdisconnect(self, r):
        self.run_script_hook("clientdisconnect", r)
        r.reply()

    def handle_serverconnection(self, sc):
        # To unify the mitmproxy script API, we call the script hook
        # "serverconnect" rather than "serverconnection".  As things are handled
        # differently in libmproxy (ClientConnect + ClientDisconnect vs
        # ServerConnection class), there is no "serverdisonnect" event at the
        # moment.
        self.run_script_hook("serverconnect", sc)
        sc.reply()

    def handle_error(self, r):
        f = self.state.add_error(r)
        if f:
            self.run_script_hook("error", f)
        if self.client_playback:
            self.client_playback.clear(f)
        r.reply()
        return f

    def handle_request(self, r):
        if r.flow.client_conn and r.flow.client_conn.wfile:
            app = self.apps.get(r)
            if app:
                err = app.serve(r, r.flow.client_conn.wfile, **{"mitmproxy.master": self})
                if err:
                    self.add_event("Error in wsgi app. %s"%err, "error")
                r.reply(KILL)
                return
        f = self.state.add_request(r)
        self.replacehooks.run(f)
        self.setheaders.run(f)
        self.run_script_hook("request", f)
        self.process_new_request(f)
        return f

    def handle_response(self, r):
        f = self.state.add_response(r)
        if f:
            self.replacehooks.run(f)
            self.setheaders.run(f)
            self.run_script_hook("response", f)
            if self.client_playback:
                self.client_playback.clear(f)
            self.process_new_response(f)
            if self.stream:
                self.stream.add(f)
        else:
            r.reply()
        return f

    def shutdown(self):
        self.unload_scripts()
        controller.Master.shutdown(self)
        if self.stream:
            for i in self.state._flow_list:
                if not i.response:
                    self.stream.add(i)
            self.stop_stream()

    def start_stream(self, fp, filt):
        self.stream = FilteredFlowWriter(fp, filt)

    def stop_stream(self):
        self.stream.fo.close()
        self.stream = None



class FlowWriter:
    def __init__(self, fo):
        self.fo = fo

    def add(self, flow):
        d = flow._get_state()
        tnetstring.dump(d, self.fo)


class FlowReadError(Exception):
    @property
    def strerror(self):
        return self.args[0]


class FlowReader:
    def __init__(self, fo):
        self.fo = fo

    def stream(self):
        """
            Yields Flow objects from the dump.
        """
        off = 0
        try:
            while 1:
                data = tnetstring.load(self.fo)
                if tuple(data["version"][:2]) != version.IVERSION[:2]:
                    v = ".".join(str(i) for i in data["version"])
                    raise FlowReadError("Incompatible serialized data version: %s"%v)
                off = self.fo.tell()
                yield protocol.protocols[data["conntype"]]["flow"]._from_state(data)
        except ValueError, v:
            # Error is due to EOF
            if self.fo.tell() == off and self.fo.read() == '':
                return
            raise FlowReadError("Invalid data format.")


class FilteredFlowWriter:
    def __init__(self, fo, filt):
        self.fo = fo
        self.filt = filt

    def add(self, f):
        if self.filt and not f.match(self.filt):
            return
        d = f._get_state()
        tnetstring.dump(d, self.fo)