summary refs log tree commit diff
path: root/synapse/handlers/directory.py
blob: b7064c6624b741011f5bf622d8f1f451bc53a705 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
# Copyright 2014-2016 OpenMarket 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 logging
import string
from typing import TYPE_CHECKING, Iterable, List, Optional

from synapse.api.constants import MAX_ALIAS_LENGTH, EventTypes
from synapse.api.errors import (
    AuthError,
    CodeMessageException,
    Codes,
    NotFoundError,
    RequestSendFailed,
    ShadowBanError,
    StoreError,
    SynapseError,
)
from synapse.appservice import ApplicationService
from synapse.storage.databases.main.directory import RoomAliasMapping
from synapse.types import JsonDict, Requester, RoomAlias, UserID, get_domain_from_id

if TYPE_CHECKING:
    from synapse.server import HomeServer

logger = logging.getLogger(__name__)


class DirectoryHandler:
    def __init__(self, hs: "HomeServer"):
        self.auth = hs.get_auth()
        self.hs = hs
        self.state = hs.get_state_handler()
        self.appservice_handler = hs.get_application_service_handler()
        self.event_creation_handler = hs.get_event_creation_handler()
        self.store = hs.get_datastores().main
        self.config = hs.config
        self.enable_room_list_search = hs.config.roomdirectory.enable_room_list_search
        self.require_membership = hs.config.server.require_membership_for_aliases
        self.third_party_event_rules = hs.get_third_party_event_rules()
        self.server_name = hs.hostname

        self.federation = hs.get_federation_client()
        hs.get_federation_registry().register_query_handler(
            "directory", self.on_directory_query
        )

        self.spam_checker = hs.get_spam_checker()

    async def _create_association(
        self,
        room_alias: RoomAlias,
        room_id: str,
        servers: Optional[Iterable[str]] = None,
        creator: Optional[str] = None,
    ) -> None:
        # general association creation for both human users and app services

        for wchar in string.whitespace:
            if wchar in room_alias.localpart:
                raise SynapseError(400, "Invalid characters in room alias")

        if not self.hs.is_mine(room_alias):
            raise SynapseError(400, "Room alias must be local")
            # TODO(erikj): Change this.

        # TODO(erikj): Add transactions.
        # TODO(erikj): Check if there is a current association.
        if not servers:
            users = await self.store.get_users_in_room(room_id)
            servers = {get_domain_from_id(u) for u in users}

        if not servers:
            raise SynapseError(400, "Failed to get server list")

        await self.store.create_room_alias_association(
            room_alias, room_id, servers, creator=creator
        )

    async def create_association(
        self,
        requester: Requester,
        room_alias: RoomAlias,
        room_id: str,
        servers: Optional[List[str]] = None,
        check_membership: bool = True,
    ) -> None:
        """Attempt to create a new alias

        Args:
            requester
            room_alias
            room_id
            servers: Iterable of servers that others servers should try and join via
            check_membership: Whether to check if the user is in the room
                before the alias can be set (if the server's config requires it).
        """

        user_id = requester.user.to_string()
        room_alias_str = room_alias.to_string()

        if len(room_alias_str) > MAX_ALIAS_LENGTH:
            raise SynapseError(
                400,
                "Can't create aliases longer than %s characters" % MAX_ALIAS_LENGTH,
                Codes.INVALID_PARAM,
            )

        service = requester.app_service
        if service:
            if not service.is_interested_in_alias(room_alias_str):
                raise SynapseError(
                    400,
                    "This application service has not reserved this kind of alias.",
                    errcode=Codes.EXCLUSIVE,
                )
        else:
            # Server admins are not subject to the same constraints as normal
            # users when creating an alias (e.g. being in the room).
            is_admin = await self.auth.is_server_admin(requester.user)

            if (self.require_membership and check_membership) and not is_admin:
                rooms_for_user = await self.store.get_rooms_for_user(user_id)
                if room_id not in rooms_for_user:
                    raise AuthError(
                        403, "You must be in the room to create an alias for it"
                    )

            if not await self.spam_checker.user_may_create_room_alias(
                user_id, room_alias
            ):
                raise AuthError(403, "This user is not permitted to create this alias")

            if not self.config.roomdirectory.is_alias_creation_allowed(
                user_id, room_id, room_alias_str
            ):
                # Let's just return a generic message, as there may be all sorts of
                # reasons why we said no. TODO: Allow configurable error messages
                # per alias creation rule?
                raise SynapseError(403, "Not allowed to create alias")

            can_create = self.can_modify_alias(room_alias, user_id=user_id)
            if not can_create:
                raise AuthError(
                    400,
                    "This alias is reserved by an application service.",
                    errcode=Codes.EXCLUSIVE,
                )

        await self._create_association(room_alias, room_id, servers, creator=user_id)

    async def delete_association(
        self, requester: Requester, room_alias: RoomAlias
    ) -> str:
        """Remove an alias from the directory

        (this is only meant for human users; AS users should call
        delete_appservice_association)

        Args:
            requester
            room_alias

        Returns:
            room id that the alias used to point to

        Raises:
            NotFoundError: if the alias doesn't exist

            AuthError: if the user doesn't have perms to delete the alias (ie, the user
                is neither the creator of the alias, nor a server admin.

            SynapseError: if the alias belongs to an AS
        """
        user_id = requester.user.to_string()

        try:
            can_delete = await self._user_can_delete_alias(room_alias, user_id)
        except StoreError as e:
            if e.code == 404:
                raise NotFoundError("Unknown room alias")
            raise

        if not can_delete:
            raise AuthError(403, "You don't have permission to delete the alias.")

        can_delete = self.can_modify_alias(room_alias, user_id=user_id)
        if not can_delete:
            raise SynapseError(
                400,
                "This alias is reserved by an application service.",
                errcode=Codes.EXCLUSIVE,
            )

        room_id = await self._delete_association(room_alias)
        if room_id is None:
            # It's possible someone else deleted the association after the
            # checks above, but before we did the deletion.
            raise NotFoundError("Unknown room alias")

        try:
            await self._update_canonical_alias(requester, user_id, room_id, room_alias)
        except ShadowBanError as e:
            logger.info("Failed to update alias events due to shadow-ban: %s", e)
        except AuthError as e:
            logger.info("Failed to update alias events: %s", e)

        return room_id

    async def delete_appservice_association(
        self, service: ApplicationService, room_alias: RoomAlias
    ) -> None:
        if not service.is_interested_in_alias(room_alias.to_string()):
            raise SynapseError(
                400,
                "This application service has not reserved this kind of alias",
                errcode=Codes.EXCLUSIVE,
            )
        await self._delete_association(room_alias)

    async def _delete_association(self, room_alias: RoomAlias) -> Optional[str]:
        if not self.hs.is_mine(room_alias):
            raise SynapseError(400, "Room alias must be local")

        room_id = await self.store.delete_room_alias(room_alias)

        return room_id

    async def get_association(self, room_alias: RoomAlias) -> JsonDict:
        room_id = None
        if self.hs.is_mine(room_alias):
            result: Optional[
                RoomAliasMapping
            ] = await self.get_association_from_room_alias(room_alias)

            if result:
                room_id = result.room_id
                servers = result.servers
        else:
            try:
                fed_result: Optional[JsonDict] = await self.federation.make_query(
                    destination=room_alias.domain,
                    query_type="directory",
                    args={"room_alias": room_alias.to_string()},
                    retry_on_dns_fail=False,
                    ignore_backoff=True,
                )
            except RequestSendFailed:
                raise SynapseError(502, "Failed to fetch alias")
            except CodeMessageException as e:
                logging.warning("Error retrieving alias")
                if e.code == 404:
                    fed_result = None
                else:
                    raise SynapseError(502, "Failed to fetch alias")

            if fed_result and "room_id" in fed_result and "servers" in fed_result:
                room_id = fed_result["room_id"]
                servers = fed_result["servers"]

        if not room_id:
            raise SynapseError(
                404,
                "Room alias %s not found" % (room_alias.to_string(),),
                Codes.NOT_FOUND,
            )

        users = await self.store.get_users_in_room(room_id)
        extra_servers = {get_domain_from_id(u) for u in users}
        servers_set = set(extra_servers) | set(servers)

        # If this server is in the list of servers, return it first.
        if self.server_name in servers_set:
            servers = [self.server_name] + [
                s for s in servers_set if s != self.server_name
            ]
        else:
            servers = list(servers_set)

        return {"room_id": room_id, "servers": servers}

    async def on_directory_query(self, args: JsonDict) -> JsonDict:
        room_alias = RoomAlias.from_string(args["room_alias"])
        if not self.hs.is_mine(room_alias):
            raise SynapseError(400, "Room Alias is not hosted on this homeserver")

        result = await self.get_association_from_room_alias(room_alias)

        if result is not None:
            return {"room_id": result.room_id, "servers": result.servers}
        else:
            raise SynapseError(
                404,
                "Room alias %r not found" % (room_alias.to_string(),),
                Codes.NOT_FOUND,
            )

    async def _update_canonical_alias(
        self, requester: Requester, user_id: str, room_id: str, room_alias: RoomAlias
    ) -> None:
        """
        Send an updated canonical alias event if the removed alias was set as
        the canonical alias or listed in the alt_aliases field.

        Raises:
            ShadowBanError if the requester has been shadow-banned.
        """
        alias_event = await self.state.get_current_state(
            room_id, EventTypes.CanonicalAlias, ""
        )

        # There is no canonical alias, nothing to do.
        if not alias_event:
            return

        # Obtain a mutable version of the event content.
        content = dict(alias_event.content)
        send_update = False

        # Remove the alias property if it matches the removed alias.
        alias_str = room_alias.to_string()
        if alias_event.content.get("alias", "") == alias_str:
            send_update = True
            content.pop("alias", "")

        # Filter the alt_aliases property for the removed alias. Note that the
        # value is not modified if alt_aliases is of an unexpected form.
        alt_aliases = content.get("alt_aliases")
        if isinstance(alt_aliases, (list, tuple)) and alias_str in alt_aliases:
            send_update = True
            alt_aliases = [alias for alias in alt_aliases if alias != alias_str]

            if alt_aliases:
                content["alt_aliases"] = alt_aliases
            else:
                del content["alt_aliases"]

        if send_update:
            await self.event_creation_handler.create_and_send_nonmember_event(
                requester,
                {
                    "type": EventTypes.CanonicalAlias,
                    "state_key": "",
                    "room_id": room_id,
                    "sender": user_id,
                    "content": content,
                },
                ratelimit=False,
            )

    async def get_association_from_room_alias(
        self, room_alias: RoomAlias
    ) -> Optional[RoomAliasMapping]:
        result = await self.store.get_association_from_room_alias(room_alias)
        if not result:
            # Query AS to see if it exists
            as_handler = self.appservice_handler
            result = await as_handler.query_room_alias_exists(room_alias)
        return result

    def can_modify_alias(self, alias: RoomAlias, user_id: Optional[str] = None) -> bool:
        # Any application service "interested" in an alias they are regexing on
        # can modify the alias.
        # Users can only modify the alias if ALL the interested services have
        # non-exclusive locks on the alias (or there are no interested services)
        services = self.store.get_app_services()
        interested_services = [
            s for s in services if s.is_interested_in_alias(alias.to_string())
        ]

        for service in interested_services:
            if user_id == service.sender:
                # this user IS the app service so they can do whatever they like
                return True
            elif service.is_exclusive_alias(alias.to_string()):
                # another service has an exclusive lock on this alias.
                return False
        # either no interested services, or no service with an exclusive lock
        return True

    async def _user_can_delete_alias(self, alias: RoomAlias, user_id: str) -> bool:
        """Determine whether a user can delete an alias.

        One of the following must be true:

        1. The user created the alias.
        2. The user is a server administrator.
        3. The user has a power-level sufficient to send a canonical alias event
           for the current room.

        """
        creator = await self.store.get_room_alias_creator(alias.to_string())

        if creator == user_id:
            return True

        # Resolve the alias to the corresponding room.
        room_mapping = await self.get_association(alias)
        room_id = room_mapping["room_id"]
        if not room_id:
            return False

        return await self.auth.check_can_change_room_list(
            room_id, UserID.from_string(user_id)
        )

    async def edit_published_room_list(
        self, requester: Requester, room_id: str, visibility: str
    ) -> None:
        """Edit the entry of the room in the published room list.

        requester
        room_id
        visibility: "public" or "private"
        """
        user_id = requester.user.to_string()

        if not await self.spam_checker.user_may_publish_room(user_id, room_id):
            raise AuthError(
                403, "This user is not permitted to publish rooms to the room list"
            )

        if requester.is_guest:
            raise AuthError(403, "Guests cannot edit the published room list")

        if visibility not in ["public", "private"]:
            raise SynapseError(400, "Invalid visibility setting")

        if visibility == "public" and not self.enable_room_list_search:
            # The room list has been disabled.
            raise AuthError(
                403, "This user is not permitted to publish rooms to the room list"
            )

        room = await self.store.get_room(room_id)
        if room is None:
            raise SynapseError(400, "Unknown room")

        can_change_room_list = await self.auth.check_can_change_room_list(
            room_id, requester.user
        )
        if not can_change_room_list:
            raise AuthError(
                403,
                "This server requires you to be a moderator in the room to"
                " edit its room list entry",
            )

        making_public = visibility == "public"
        if making_public:
            room_aliases = await self.store.get_aliases_for_room(room_id)
            canonical_alias = await self.store.get_canonical_alias_for_room(room_id)
            if canonical_alias:
                room_aliases.append(canonical_alias)

            if not self.config.roomdirectory.is_publishing_room_allowed(
                user_id, room_id, room_aliases
            ):
                # Let's just return a generic message, as there may be all sorts of
                # reasons why we said no. TODO: Allow configurable error messages
                # per alias creation rule?
                raise SynapseError(403, "Not allowed to publish room")

            # Check if publishing is blocked by a third party module
            allowed_by_third_party_rules = await (
                self.third_party_event_rules.check_visibility_can_be_modified(
                    room_id, visibility
                )
            )
            if not allowed_by_third_party_rules:
                raise SynapseError(403, "Not allowed to publish room")

        await self.store.set_room_is_public(room_id, making_public)

    async def edit_published_appservice_room_list(
        self, appservice_id: str, network_id: str, room_id: str, visibility: str
    ) -> None:
        """Add or remove a room from the appservice/network specific public
        room list.

        Args:
            appservice_id: ID of the appservice that owns the list
            network_id: The ID of the network the list is associated with
            room_id
            visibility: either "public" or "private"
        """
        if visibility not in ["public", "private"]:
            raise SynapseError(400, "Invalid visibility setting")

        await self.store.set_room_is_public_appservice(
            room_id, appservice_id, network_id, visibility == "public"
        )

    async def get_aliases_for_room(
        self, requester: Requester, room_id: str
    ) -> List[str]:
        """
        Get a list of the aliases that currently point to this room on this server
        """
        # allow access to server admins and current members of the room
        is_admin = await self.auth.is_server_admin(requester.user)
        if not is_admin:
            await self.auth.check_user_in_room_or_world_readable(
                room_id, requester.user.to_string()
            )

        return await self.store.get_aliases_for_room(room_id)