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Diffstat (limited to 'synapse/rest/consent/consent_resource.py')
| -rw-r--r-- | synapse/rest/consent/consent_resource.py | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/synapse/rest/consent/consent_resource.py b/synapse/rest/consent/consent_resource.py new file mode 100644 index 0000000000..147ff7d79b --- /dev/null +++ b/synapse/rest/consent/consent_resource.py @@ -0,0 +1,220 @@ +# -*- coding: utf-8 -*- +# Copyright 2018 New Vector Ltd +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +import hmac +import logging +from hashlib import sha256 +from os import path + +from six.moves import http_client + +import jinja2 +from jinja2 import TemplateNotFound + +from twisted.internet import defer +from twisted.web.resource import Resource +from twisted.web.server import NOT_DONE_YET + +from synapse.api.errors import NotFoundError, StoreError, SynapseError +from synapse.config import ConfigError +from synapse.http.server import finish_request, wrap_html_request_handler +from synapse.http.servlet import parse_string +from synapse.types import UserID + +# language to use for the templates. TODO: figure this out from Accept-Language +TEMPLATE_LANGUAGE = "en" + +logger = logging.getLogger(__name__) + +# use hmac.compare_digest if we have it (python 2.7.7), else just use equality +if hasattr(hmac, "compare_digest"): + compare_digest = hmac.compare_digest +else: + def compare_digest(a, b): + return a == b + + +class ConsentResource(Resource): + """A twisted Resource to display a privacy policy and gather consent to it + + When accessed via GET, returns the privacy policy via a template. + + When accessed via POST, records the user's consent in the database and + displays a success page. + + The config should include a template_dir setting which contains templates + for the HTML. The directory should contain one subdirectory per language + (eg, 'en', 'fr'), and each language directory should contain the policy + document (named as '<version>.html') and a success page (success.html). + + Both forms take a set of parameters from the browser. For the POST form, + these are normally sent as form parameters (but may be query-params); for + GET requests they must be query params. These are: + + u: the complete mxid, or the localpart of the user giving their + consent. Required for both GET (where it is used as an input to the + template) and for POST (where it is used to find the row in the db + to update). + + h: hmac_sha256(secret, u), where 'secret' is the privacy_secret in the + config file. If it doesn't match, the request is 403ed. + + v: the version of the privacy policy being agreed to. + + For GET: optional, and defaults to whatever was set in the config + file. Used to choose the version of the policy to pick from the + templates directory. + + For POST: required; gives the value to be recorded in the database + against the user. + """ + def __init__(self, hs): + """ + Args: + hs (synapse.server.HomeServer): homeserver + """ + Resource.__init__(self) + + self.hs = hs + self.store = hs.get_datastore() + + # this is required by the request_handler wrapper + self.clock = hs.get_clock() + + self._default_consent_version = hs.config.user_consent_version + if self._default_consent_version is None: + raise ConfigError( + "Consent resource is enabled but user_consent section is " + "missing in config file.", + ) + + # daemonize changes the cwd to /, so make the path absolute now. + consent_template_directory = path.abspath( + hs.config.user_consent_template_dir, + ) + if not path.isdir(consent_template_directory): + raise ConfigError( + "Could not find template directory '%s'" % ( + consent_template_directory, + ), + ) + + loader = jinja2.FileSystemLoader(consent_template_directory) + self._jinja_env = jinja2.Environment( + loader=loader, + autoescape=jinja2.select_autoescape(['html', 'htm', 'xml']), + ) + + if hs.config.form_secret is None: + raise ConfigError( + "Consent resource is enabled but form_secret is not set in " + "config file. It should be set to an arbitrary secret string.", + ) + + self._hmac_secret = hs.config.form_secret.encode("utf-8") + + def render_GET(self, request): + self._async_render_GET(request) + return NOT_DONE_YET + + @wrap_html_request_handler + @defer.inlineCallbacks + def _async_render_GET(self, request): + """ + Args: + request (twisted.web.http.Request): + """ + + version = parse_string(request, "v", + default=self._default_consent_version) + username = parse_string(request, "u", required=True) + userhmac = parse_string(request, "h", required=True) + + self._check_hash(username, userhmac) + + if username.startswith('@'): + qualified_user_id = username + else: + qualified_user_id = UserID(username, self.hs.hostname).to_string() + + u = yield self.store.get_user_by_id(qualified_user_id) + if u is None: + raise NotFoundError("Unknown user") + + try: + self._render_template( + request, "%s.html" % (version,), + user=username, userhmac=userhmac, version=version, + has_consented=(u["consent_version"] == version), + ) + except TemplateNotFound: + raise NotFoundError("Unknown policy version") + + def render_POST(self, request): + self._async_render_POST(request) + return NOT_DONE_YET + + @wrap_html_request_handler + @defer.inlineCallbacks + def _async_render_POST(self, request): + """ + Args: + request (twisted.web.http.Request): + """ + version = parse_string(request, "v", required=True) + username = parse_string(request, "u", required=True) + userhmac = parse_string(request, "h", required=True) + + self._check_hash(username, userhmac) + + if username.startswith('@'): + qualified_user_id = username + else: + qualified_user_id = UserID(username, self.hs.hostname).to_string() + + try: + yield self.store.user_set_consent_version(qualified_user_id, version) + except StoreError as e: + if e.code != 404: + raise + raise NotFoundError("Unknown user") + + try: + self._render_template(request, "success.html") + except TemplateNotFound: + raise NotFoundError("success.html not found") + + def _render_template(self, request, template_name, **template_args): + # get_template checks for ".." so we don't need to worry too much + # about path traversal here. + template_html = self._jinja_env.get_template( + path.join(TEMPLATE_LANGUAGE, template_name) + ) + html_bytes = template_html.render(**template_args).encode("utf8") + + request.setHeader(b"Content-Type", b"text/html; charset=utf-8") + request.setHeader(b"Content-Length", b"%i" % len(html_bytes)) + request.write(html_bytes) + finish_request(request) + + def _check_hash(self, userid, userhmac): + want_mac = hmac.new( + key=self._hmac_secret, + msg=userid, + digestmod=sha256, + ).hexdigest() + + if not compare_digest(want_mac, userhmac): + raise SynapseError(http_client.FORBIDDEN, "HMAC incorrect") |