Uniformize spam-checker API, part 3: Expand check_event_for_spam with the ability to return additional fields (#12846)

Signed-off-by: David Teller <davidt@element.io>
This commit is contained in:
David Teller 2022-05-30 18:24:56 +02:00 committed by GitHub
parent 1fd1856afc
commit af7db19e1e
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5 changed files with 43 additions and 17 deletions

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@ -0,0 +1 @@
Update to `check_event_for_spam`. Deprecate the current callback signature, replace it with a new signature that is both less ambiguous (replacing booleans with explicit allow/block) and more powerful (ability to return explicit error codes).

1
changelog.d/12846.misc Normal file
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@ -0,0 +1 @@
Experimental: expand `check_event_for_spam` with ability to return additional fields. This enables spam-checker implementations to experiment with mechanisms to give users more information about why they are blocked and whether any action is needed from them to be unblocked.

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@ -146,7 +146,13 @@ class SynapseError(CodeMessageException):
errcode: Matrix error code e.g 'M_FORBIDDEN'
"""
def __init__(self, code: int, msg: str, errcode: str = Codes.UNKNOWN):
def __init__(
self,
code: int,
msg: str,
errcode: str = Codes.UNKNOWN,
additional_fields: Optional[Dict] = None,
):
"""Constructs a synapse error.
Args:
@ -156,9 +162,13 @@ class SynapseError(CodeMessageException):
"""
super().__init__(code, msg)
self.errcode = errcode
if additional_fields is None:
self._additional_fields: Dict = {}
else:
self._additional_fields = dict(additional_fields)
def error_dict(self) -> "JsonDict":
return cs_error(self.msg, self.errcode)
return cs_error(self.msg, self.errcode, **self._additional_fields)
class InvalidAPICallError(SynapseError):
@ -183,14 +193,7 @@ class ProxiedRequestError(SynapseError):
errcode: str = Codes.UNKNOWN,
additional_fields: Optional[Dict] = None,
):
super().__init__(code, msg, errcode)
if additional_fields is None:
self._additional_fields: Dict = {}
else:
self._additional_fields = dict(additional_fields)
def error_dict(self) -> "JsonDict":
return cs_error(self.msg, self.errcode, **self._additional_fields)
super().__init__(code, msg, errcode, additional_fields)
class ConsentNotGivenError(SynapseError):

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@ -21,6 +21,7 @@ from typing import (
Awaitable,
Callable,
Collection,
Dict,
List,
Optional,
Tuple,
@ -41,13 +42,17 @@ if TYPE_CHECKING:
logger = logging.getLogger(__name__)
CHECK_EVENT_FOR_SPAM_CALLBACK = Callable[
["synapse.events.EventBase"],
Awaitable[
Union[
Allow,
Codes,
# Highly experimental, not officially part of the spamchecker API, may
# disappear without warning depending on the results of ongoing
# experiments.
# Use this to return additional information as part of an error.
Tuple[Codes, Dict],
# Deprecated
bool,
# Deprecated
@ -270,7 +275,7 @@ class SpamChecker:
async def check_event_for_spam(
self, event: "synapse.events.EventBase"
) -> Union[Decision, str]:
) -> Union[Decision, Tuple[Codes, Dict], str]:
"""Checks if a given event is considered "spammy" by this server.
If the server considers an event spammy, then it will be rejected if
@ -293,9 +298,9 @@ class SpamChecker:
with Measure(
self.clock, "{}.{}".format(callback.__module__, callback.__qualname__)
):
res: Union[Decision, str, bool] = await delay_cancellation(
callback(event)
)
res: Union[
Decision, Tuple[Codes, Dict], str, bool
] = await delay_cancellation(callback(event))
if res is False or res is Allow.ALLOW:
# This spam-checker accepts the event.
# Other spam-checkers may reject it, though.
@ -305,8 +310,9 @@ class SpamChecker:
# return value `True`
return Codes.FORBIDDEN
else:
# This spam-checker rejects the event either with a `str`
# or with a `Codes`. In either case, we stop here.
# This spam-checker rejects the event either with a `str`,
# with a `Codes` or with a `Tuple[Codes, Dict]`. In either
# case, we stop here.
return res
# No spam-checker has rejected the event, let it pass.

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@ -895,6 +895,21 @@ class EventCreationHandler:
spam_check = await self.spam_checker.check_event_for_spam(event)
if spam_check is not synapse.spam_checker_api.Allow.ALLOW:
if isinstance(spam_check, tuple):
try:
[code, dict] = spam_check
raise SynapseError(
403,
"This message had been rejected as probable spam",
code,
dict,
)
except ValueError:
logger.error(
"Spam-check module returned invalid error value. Expecting [code, dict], got %s",
spam_check,
)
spam_check = Codes.FORBIDDEN
raise SynapseError(
403, "This message had been rejected as probable spam", spam_check
)