forked-synapse/synapse/handlers/identity.py

# -*- coding: utf-8 -*-
# Copyright 2015, 2016 OpenMarket Ltd
# Copyright 2017 Vector Creations Ltd
# Copyright 2018, 2019 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.

"""Utilities for interacting with Identity Servers"""

import logging

from canonicaljson import json
from signedjson.key import decode_verify_key_bytes
from signedjson.sign import verify_signed_json
from unpaddedbase64 import decode_base64

from twisted.internet import defer

from synapse.api.errors import (
    AuthError,
    CodeMessageException,
    Codes,
    HttpResponseException,
    ProxiedRequestError,
    SynapseError,
)

from ._base import BaseHandler

logger = logging.getLogger(__name__)


class IdentityHandler(BaseHandler):

    def __init__(self, hs):
        super(IdentityHandler, self).__init__(hs)

        self.http_client = hs.get_simple_http_client()
        self.federation_http_client = hs.get_http_client()

        self.trusted_id_servers = set(hs.config.trusted_third_party_id_servers)
        self.trust_any_id_server_just_for_testing_do_not_use = (
            hs.config.use_insecure_ssl_client_just_for_testing_do_not_use
        )
        self.rewrite_identity_server_urls = hs.config.rewrite_identity_server_urls
        self._enable_lookup = hs.config.enable_3pid_lookup

    def _should_trust_id_server(self, id_server):
        if id_server not in self.trusted_id_servers:
            if self.trust_any_id_server_just_for_testing_do_not_use:
                logger.warn(
                    "Trusting untrustworthy ID server %r even though it isn't"
                    " in the trusted id list for testing because"
                    " 'use_insecure_ssl_client_just_for_testing_do_not_use'"
                    " is set in the config",
                    id_server,
                )
            else:
                return False
        return True

    @defer.inlineCallbacks
    def threepid_from_creds(self, creds):
        if 'id_server' in creds:
            id_server = creds['id_server']
        elif 'idServer' in creds:
            id_server = creds['idServer']
        else:
            raise SynapseError(400, "No id_server in creds")

        if 'client_secret' in creds:
            client_secret = creds['client_secret']
        elif 'clientSecret' in creds:
            client_secret = creds['clientSecret']
        else:
            raise SynapseError(400, "No client_secret in creds")

        if not self._should_trust_id_server(id_server):
            logger.warn(
                '%s is not a trusted ID server: rejecting 3pid ' +
                'credentials', id_server
            )
            defer.returnValue(None)
        # if we have a rewrite rule set for the identity server,
        # apply it now.
        if id_server in self.rewrite_identity_server_urls:
            id_server = self.rewrite_identity_server_urls[id_server]
        try:
            data = yield self.http_client.get_json(
                "https://%s%s" % (
                    id_server,
                    "/_matrix/identity/api/v1/3pid/getValidated3pid"
                ),
                {'sid': creds['sid'], 'client_secret': client_secret}
            )
        except HttpResponseException as e:
            logger.info("getValidated3pid failed with Matrix error: %r", e)
            raise e.to_synapse_error()

        if 'medium' in data:
            defer.returnValue(data)
        defer.returnValue(None)

    @defer.inlineCallbacks
    def bind_threepid(self, creds, mxid):
        logger.debug("binding threepid %r to %s", creds, mxid)
        data = None

        if 'id_server' in creds:
            id_server = creds['id_server']
        elif 'idServer' in creds:
            id_server = creds['idServer']
        else:
            raise SynapseError(400, "No id_server in creds")

        if 'client_secret' in creds:
            client_secret = creds['client_secret']
        elif 'clientSecret' in creds:
            client_secret = creds['clientSecret']
        else:
            raise SynapseError(400, "No client_secret in creds")
        # if we have a rewrite rule set for the identity server,
        # apply it now.
        if id_server in self.rewrite_identity_server_urls:
            id_server = self.rewrite_identity_server_urls[id_server]
        try:
            data = yield self.http_client.post_urlencoded_get_json(
                "https://%s%s" % (
                    id_server, "/_matrix/identity/api/v1/3pid/bind"
                ),
                {
                    'sid': creds['sid'],
                    'client_secret': client_secret,
                    'mxid': mxid,
                }
            )
            logger.debug("bound threepid %r to %s", creds, mxid)

            # Remember where we bound the threepid
            yield self.store.add_user_bound_threepid(
                user_id=mxid,
                medium=data["medium"],
                address=data["address"],
                id_server=id_server,
            )
        except CodeMessageException as e:
            data = json.loads(e.msg)  # XXX WAT?
        defer.returnValue(data)

    @defer.inlineCallbacks
    def try_unbind_threepid(self, mxid, threepid):
        """Removes a binding from an identity server

        Args:
            mxid (str): Matrix user ID of binding to be removed
            threepid (dict): Dict with medium & address of binding to be
                removed, and an optional id_server.

        Raises:
            SynapseError: If we failed to contact the identity server

        Returns:
            Deferred[bool]: True on success, otherwise False if the identity
            server doesn't support unbinding (or no identity server found to
            contact).
        """
        if threepid.get("id_server"):
            id_servers = [threepid["id_server"]]
        else:
            id_servers = yield self.store.get_id_servers_user_bound(
                user_id=mxid,
                medium=threepid["medium"],
                address=threepid["address"],
            )

        # We don't know where to unbind, so we don't have a choice but to return
        if not id_servers:
            defer.returnValue(False)

        changed = True
        for id_server in id_servers:
            changed &= yield self.try_unbind_threepid_with_id_server(
                mxid, threepid, id_server,
            )

        defer.returnValue(changed)

    @defer.inlineCallbacks
    def try_unbind_threepid_with_id_server(self, mxid, threepid, id_server):
        """Removes a binding from an identity server

        Args:
            mxid (str): Matrix user ID of binding to be removed
            threepid (dict): Dict with medium & address of binding to be removed
            id_server (str): Identity server to unbind from

        Raises:
            SynapseError: If we failed to contact the identity server

        Returns:
            Deferred[bool]: True on success, otherwise False if the identity
            server doesn't support unbinding
        """
        url = "https://%s/_matrix/identity/api/v1/3pid/unbind" % (id_server,)
        content = {
            "mxid": mxid,
            "threepid": {
                "medium": threepid["medium"],
                "address": threepid["address"],
            },
        }

        # we abuse the federation http client to sign the request, but we have to send it
        # using the normal http client since we don't want the SRV lookup and want normal
        # 'browser-like' HTTPS.
        auth_headers = self.federation_http_client.build_auth_headers(
            destination=None,
            method='POST',
            url_bytes='/_matrix/identity/api/v1/3pid/unbind'.encode('ascii'),
            content=content,
            destination_is=id_server,
        )
        headers = {
            b"Authorization": auth_headers,
        }

        # if we have a rewrite rule set for the identity server,
        # apply it now.
        #
        # Note that destination_is has to be the real id_server, not
        # the server we connect to.
        if id_server in self.rewrite_identity_server_urls:
            id_server = self.rewrite_identity_server_urls[id_server]

        url = "https://%s/_matrix/identity/api/v1/3pid/unbind" % (id_server,)

        try:
            yield self.http_client.post_json_get_json(
                url,
                content,
                headers,
            )
            changed = True
        except HttpResponseException as e:
            changed = False
            if e.code in (400, 404, 501,):
                # The remote server probably doesn't support unbinding (yet)
                logger.warn("Received %d response while unbinding threepid", e.code)
            else:
                logger.error("Failed to unbind threepid on identity server: %s", e)
                raise SynapseError(502, "Failed to contact identity server")

        yield self.store.remove_user_bound_threepid(
            user_id=mxid,
            medium=threepid["medium"],
            address=threepid["address"],
            id_server=id_server,
        )

        defer.returnValue(changed)

    @defer.inlineCallbacks
    def requestEmailToken(self, id_server, email, client_secret, send_attempt, **kwargs):
        if not self._should_trust_id_server(id_server):
            raise SynapseError(
                400, "Untrusted ID server '%s'" % id_server,
                Codes.SERVER_NOT_TRUSTED
            )

        params = {
            'email': email,
            'client_secret': client_secret,
            'send_attempt': send_attempt,
        }
        params.update(kwargs)
        # if we have a rewrite rule set for the identity server,
        # apply it now.
        if id_server in self.rewrite_identity_server_urls:
            id_server = self.rewrite_identity_server_urls[id_server]
        try:
            data = yield self.http_client.post_json_get_json(
                "https://%s%s" % (
                    id_server,
                    "/_matrix/identity/api/v1/validate/email/requestToken"
                ),
                params
            )
            defer.returnValue(data)
        except HttpResponseException as e:
            logger.info("Proxied requestToken failed: %r", e)
            raise e.to_synapse_error()

    @defer.inlineCallbacks
    def requestMsisdnToken(
            self, id_server, country, phone_number,
            client_secret, send_attempt, **kwargs
    ):
        if not self._should_trust_id_server(id_server):
            raise SynapseError(
                400, "Untrusted ID server '%s'" % id_server,
                Codes.SERVER_NOT_TRUSTED
            )

        params = {
            'country': country,
            'phone_number': phone_number,
            'client_secret': client_secret,
            'send_attempt': send_attempt,
        }
        params.update(kwargs)
        # if we have a rewrite rule set for the identity server,
        # apply it now.
        if id_server in self.rewrite_identity_server_urls:
            id_server = self.rewrite_identity_server_urls[id_server]
        try:
            data = yield self.http_client.post_json_get_json(
                "https://%s%s" % (
                    id_server,
                    "/_matrix/identity/api/v1/validate/msisdn/requestToken"
                ),
                params
            )
            defer.returnValue(data)
        except HttpResponseException as e:
            logger.info("Proxied requestToken failed: %r", e)
            raise e.to_synapse_error()

    @defer.inlineCallbacks
    def lookup_3pid(self, id_server, medium, address):
        """Looks up a 3pid in the passed identity server.

        Args:
            id_server (str): The server name (including port, if required)
                of the identity server to use.
            medium (str): The type of the third party identifier (e.g. "email").
            address (str): The third party identifier (e.g. "foo@example.com").

        Returns:
            Deferred[dict]: The result of the lookup. See
            https://matrix.org/docs/spec/identity_service/r0.1.0.html#association-lookup
            for details
        """
        if not self._should_trust_id_server(id_server):
            raise SynapseError(
                400, "Untrusted ID server '%s'" % id_server,
                Codes.SERVER_NOT_TRUSTED
            )

        if not self._enable_lookup:
            raise AuthError(
                403, "Looking up third-party identifiers is denied from this server",
            )

        target = self.rewrite_identity_server_urls.get(id_server, id_server)

        try:
            data = yield self.http_client.get_json(
                "https://%s/_matrix/identity/api/v1/lookup" % (target,),
                {
                    "medium": medium,
                    "address": address,
                }
            )

            if "mxid" in data:
                if "signatures" not in data:
                    raise AuthError(401, "No signatures on 3pid binding")
                yield self._verify_any_signature(data, id_server)

        except HttpResponseException as e:
            logger.info("Proxied lookup failed: %r", e)
            raise e.to_synapse_error()
        except IOError as e:
            logger.info("Failed to contact %r: %s", id_server, e)
            raise ProxiedRequestError(503, "Failed to contact identity server")

        defer.returnValue(data)

    @defer.inlineCallbacks
    def bulk_lookup_3pid(self, id_server, threepids):
        """Looks up given 3pids in the passed identity server.

        Args:
            id_server (str): The server name (including port, if required)
                of the identity server to use.
            threepids ([[str, str]]): The third party identifiers to lookup, as
                a list of 2-string sized lists ([medium, address]).

        Returns:
            Deferred[dict]: The result of the lookup. See
            https://matrix.org/docs/spec/identity_service/r0.1.0.html#association-lookup
            for details
        """
        if not self._should_trust_id_server(id_server):
            raise SynapseError(
                400, "Untrusted ID server '%s'" % id_server,
                Codes.SERVER_NOT_TRUSTED
            )

        if not self._enable_lookup:
            raise AuthError(
                403, "Looking up third-party identifiers is denied from this server",
            )

        target = self.rewrite_identity_server_urls.get(id_server, id_server)

        try:
            data = yield self.http_client.post_json_get_json(
                "https://%s/_matrix/identity/api/v1/bulk_lookup" % (target,),
                {
                    "threepids": threepids,
                }
            )

        except HttpResponseException as e:
            logger.info("Proxied lookup failed: %r", e)
            raise e.to_synapse_error()
        except IOError as e:
            logger.info("Failed to contact %r: %s", id_server, e)
            raise ProxiedRequestError(503, "Failed to contact identity server")

        defer.returnValue(data)

    @defer.inlineCallbacks
    def _verify_any_signature(self, data, server_hostname):
        if server_hostname not in data["signatures"]:
            raise AuthError(401, "No signature from server %s" % (server_hostname,))

        for key_name, signature in data["signatures"][server_hostname].items():
            target = self.rewrite_identity_server_urls.get(
                server_hostname, server_hostname,
            )

            key_data = yield self.http_client.get_json(
                "https://%s/_matrix/identity/api/v1/pubkey/%s" %
                (target, key_name,),
            )
            if "public_key" not in key_data:
                raise AuthError(401, "No public key named %s from %s" %
                                (key_name, server_hostname,))
            verify_signed_json(
                data,
                server_hostname,
                decode_verify_key_bytes(key_name, decode_base64(key_data["public_key"]))
            )
            return

        raise AuthError(401, "No signature from server %s" % (server_hostname,))