396 lines
14 KiB
Python
396 lines
14 KiB
Python
# Copyright 2021 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import functools
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import logging
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import re
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import time
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from http import HTTPStatus
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from typing import TYPE_CHECKING, Any, Awaitable, Callable, Dict, Optional, Tuple, cast
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from synapse.api.errors import Codes, FederationDeniedError, SynapseError
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from synapse.api.urls import FEDERATION_V1_PREFIX
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from synapse.http.server import HttpServer, ServletCallback
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from synapse.http.servlet import parse_json_object_from_request
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from synapse.http.site import SynapseRequest
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from synapse.logging.context import run_in_background
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from synapse.logging.opentracing import (
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active_span,
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set_tag,
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span_context_from_request,
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start_active_span,
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start_active_span_follows_from,
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whitelisted_homeserver,
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)
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from synapse.types import JsonDict
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from synapse.util.cancellation import is_function_cancellable
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from synapse.util.ratelimitutils import FederationRateLimiter
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from synapse.util.stringutils import parse_and_validate_server_name
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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class AuthenticationError(SynapseError):
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"""There was a problem authenticating the request"""
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class NoAuthenticationError(AuthenticationError):
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"""The request had no authentication information"""
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class Authenticator:
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def __init__(self, hs: "HomeServer"):
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self._clock = hs.get_clock()
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self.keyring = hs.get_keyring()
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self.server_name = hs.hostname
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self.store = hs.get_datastores().main
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self.federation_domain_whitelist = (
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hs.config.federation.federation_domain_whitelist
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)
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self.notifier = hs.get_notifier()
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self.replication_client = None
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if hs.config.worker.worker_app:
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self.replication_client = hs.get_replication_command_handler()
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# A method just so we can pass 'self' as the authenticator to the Servlets
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async def authenticate_request(
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self, request: SynapseRequest, content: Optional[JsonDict]
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) -> str:
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now = self._clock.time_msec()
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json_request: JsonDict = {
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"method": request.method.decode("ascii"),
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"uri": request.uri.decode("ascii"),
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"destination": self.server_name,
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"signatures": {},
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}
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if content is not None:
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json_request["content"] = content
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origin = None
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auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
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if not auth_headers:
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raise NoAuthenticationError(
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HTTPStatus.UNAUTHORIZED,
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"Missing Authorization headers",
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Codes.UNAUTHORIZED,
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)
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for auth in auth_headers:
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if auth.startswith(b"X-Matrix"):
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(origin, key, sig, destination) = _parse_auth_header(auth)
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json_request["origin"] = origin
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json_request["signatures"].setdefault(origin, {})[key] = sig
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# if the origin_server sent a destination along it needs to match our own server_name
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if destination is not None and destination != self.server_name:
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raise AuthenticationError(
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HTTPStatus.UNAUTHORIZED,
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"Destination mismatch in auth header",
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Codes.UNAUTHORIZED,
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)
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if (
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self.federation_domain_whitelist is not None
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and origin not in self.federation_domain_whitelist
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):
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raise FederationDeniedError(origin)
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if origin is None or not json_request["signatures"]:
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raise NoAuthenticationError(
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HTTPStatus.UNAUTHORIZED,
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"Missing Authorization headers",
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Codes.UNAUTHORIZED,
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)
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await self.keyring.verify_json_for_server(
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origin,
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json_request,
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now,
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)
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logger.debug("Request from %s", origin)
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request.requester = origin
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# If we get a valid signed request from the other side, its probably
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# alive
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retry_timings = await self.store.get_destination_retry_timings(origin)
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if retry_timings and retry_timings.retry_last_ts:
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run_in_background(self.reset_retry_timings, origin)
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return origin
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async def reset_retry_timings(self, origin: str) -> None:
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try:
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logger.info("Marking origin %r as up", origin)
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await self.store.set_destination_retry_timings(origin, None, 0, 0)
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# Inform the relevant places that the remote server is back up.
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self.notifier.notify_remote_server_up(origin)
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if self.replication_client:
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# If we're on a worker we try and inform master about this. The
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# replication client doesn't hook into the notifier to avoid
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# infinite loops where we send a `REMOTE_SERVER_UP` command to
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# master, which then echoes it back to us which in turn pokes
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# the notifier.
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self.replication_client.send_remote_server_up(origin)
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except Exception:
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logger.exception("Error resetting retry timings on %s", origin)
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def _parse_auth_header(header_bytes: bytes) -> Tuple[str, str, str, Optional[str]]:
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"""Parse an X-Matrix auth header
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Args:
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header_bytes: header value
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Returns:
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origin, key id, signature, destination.
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origin, key id, signature.
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Raises:
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AuthenticationError if the header could not be parsed
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"""
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try:
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header_str = header_bytes.decode("utf-8")
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params = re.split(" +", header_str)[1].split(",")
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param_dict: Dict[str, str] = {
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k.lower(): v for k, v in [param.split("=", maxsplit=1) for param in params]
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}
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def strip_quotes(value: str) -> str:
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if value.startswith('"'):
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return re.sub(
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"\\\\(.)", lambda matchobj: matchobj.group(1), value[1:-1]
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)
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else:
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return value
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origin = strip_quotes(param_dict["origin"])
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# ensure that the origin is a valid server name
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parse_and_validate_server_name(origin)
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key = strip_quotes(param_dict["key"])
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sig = strip_quotes(param_dict["sig"])
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# get the destination server_name from the auth header if it exists
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destination = param_dict.get("destination")
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if destination is not None:
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destination = strip_quotes(destination)
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else:
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destination = None
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return origin, key, sig, destination
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except Exception as e:
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logger.warning(
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"Error parsing auth header '%s': %s",
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header_bytes.decode("ascii", "replace"),
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e,
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)
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raise AuthenticationError(
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HTTPStatus.BAD_REQUEST, "Malformed Authorization header", Codes.UNAUTHORIZED
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)
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class BaseFederationServlet:
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"""Abstract base class for federation servlet classes.
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The servlet object should have a PATH attribute which takes the form of a regexp to
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match against the request path (excluding the /federation/v1 prefix).
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The servlet should also implement one or more of on_GET, on_POST, on_PUT, to match
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the appropriate HTTP method. These methods must be *asynchronous* and have the
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signature:
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on_<METHOD>(self, origin, content, query, **kwargs)
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With arguments:
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origin (str|None): The authenticated server_name of the calling server,
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unless REQUIRE_AUTH is set to False and authentication failed.
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content (str|None): decoded json body of the request. None if the
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request was a GET.
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query (dict[bytes, list[bytes]]): Query params from the request. url-decoded
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(ie, '+' and '%xx' are decoded) but note that it is *not* utf8-decoded
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yet.
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**kwargs (dict[unicode, unicode]): the dict mapping keys to path
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components as specified in the path match regexp.
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Returns:
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Optional[Tuple[int, object]]: either (response code, response object) to
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return a JSON response, or None if the request has already been handled.
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Raises:
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SynapseError: to return an error code
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Exception: other exceptions will be caught, logged, and a 500 will be
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returned.
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"""
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PATH = "" # Overridden in subclasses, the regex to match against the path.
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REQUIRE_AUTH = True
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PREFIX = FEDERATION_V1_PREFIX # Allows specifying the API version
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RATELIMIT = True # Whether to rate limit requests or not
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def __init__(
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self,
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hs: "HomeServer",
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authenticator: Authenticator,
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ratelimiter: FederationRateLimiter,
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server_name: str,
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):
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self.hs = hs
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self.authenticator = authenticator
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self.ratelimiter = ratelimiter
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self.server_name = server_name
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def _wrap(self, func: Callable[..., Awaitable[Tuple[int, Any]]]) -> ServletCallback:
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authenticator = self.authenticator
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ratelimiter = self.ratelimiter
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@functools.wraps(func)
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async def new_func(
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request: SynapseRequest, *args: Any, **kwargs: str
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) -> Optional[Tuple[int, Any]]:
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"""A callback which can be passed to HttpServer.RegisterPaths
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Args:
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request:
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*args: unused?
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**kwargs: the dict mapping keys to path components as specified
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in the path match regexp.
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Returns:
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(response code, response object) as returned by the callback method.
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None if the request has already been handled.
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"""
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content = None
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if request.method in [b"PUT", b"POST"]:
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# TODO: Handle other method types? other content types?
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content = parse_json_object_from_request(request)
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try:
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with start_active_span("authenticate_request"):
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origin: Optional[str] = await authenticator.authenticate_request(
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request, content
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)
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except NoAuthenticationError:
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origin = None
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if self.REQUIRE_AUTH:
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logger.warning(
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"authenticate_request failed: missing authentication"
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)
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raise
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except Exception as e:
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logger.warning("authenticate_request failed: %s", e)
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raise
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# update the active opentracing span with the authenticated entity
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set_tag("authenticated_entity", str(origin))
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# if the origin is authenticated and whitelisted, use its span context
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# as the parent.
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context = None
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if origin and whitelisted_homeserver(origin):
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context = span_context_from_request(request)
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if context:
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servlet_span = active_span()
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# a scope which uses the origin's context as a parent
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processing_start_time = time.time()
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scope = start_active_span_follows_from(
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"incoming-federation-request",
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child_of=context,
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contexts=(servlet_span,),
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start_time=processing_start_time,
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)
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else:
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# just use our context as a parent
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scope = start_active_span(
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"incoming-federation-request",
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)
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try:
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with scope:
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if origin and self.RATELIMIT:
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with ratelimiter.ratelimit(origin) as d:
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await d
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if request._disconnected:
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logger.warning(
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"client disconnected before we started processing "
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"request"
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)
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return None
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response = await func(
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origin, content, request.args, *args, **kwargs
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)
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else:
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response = await func(
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origin, content, request.args, *args, **kwargs
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)
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finally:
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# if we used the origin's context as the parent, add a new span using
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# the servlet span as a parent, so that we have a link
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if context:
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scope2 = start_active_span_follows_from(
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"process-federation_request",
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contexts=(scope.span,),
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start_time=processing_start_time,
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)
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scope2.close()
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return response
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return cast(ServletCallback, new_func)
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def register(self, server: HttpServer) -> None:
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pattern = re.compile("^" + self.PREFIX + self.PATH + "$")
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for method in ("GET", "PUT", "POST"):
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code = getattr(self, "on_%s" % (method), None)
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if code is None:
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continue
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if is_function_cancellable(code):
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# The wrapper added by `self._wrap` will inherit the cancellable flag,
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# but the wrapper itself does not support cancellation yet.
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# Once resolved, the cancellation tests in
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# `tests/federation/transport/server/test__base.py` can be re-enabled.
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raise Exception(
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f"{self.__class__.__name__}.on_{method} has been marked as "
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"cancellable, but federation servlets do not support cancellation "
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"yet."
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)
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server.register_paths(
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method,
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(pattern,),
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self._wrap(code),
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self.__class__.__name__,
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)
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