forked-synapse/synapse/federation/transport/server/_base.py
Patrick Cloke d8cc86eff4
Remove redundant types from comments. (#14412)
Remove type hints from comments which have been added
as Python type hints. This helps avoid drift between comments
and reality, as well as removing redundant information.

Also adds some missing type hints which were simple to fill in.
2022-11-16 15:25:24 +00:00

396 lines
14 KiB
Python

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