move contains_url_filter helper to utils::filter

The plan is to move all of the per-event checks into the
pdu_event_allowed function.

src/api/client_server/message.rs

@@ -6,13 +6,12 @@ use std::{
 use ruma::{
 	api::client::{
 		error::ErrorKind,
-		filter::{RoomEventFilter, UrlFilter},
 		message::{get_message_events, send_message_event},
 	},
 	events::{MessageLikeEventType, StateEventType},
 	RoomId, UserId,
 };
-use serde_json::{from_str, Value};
+use serde_json::from_str;
 
 use crate::{
 	service::{pdu::PduBuilder, rooms::timeline::PduCount},
@@ -176,7 +175,7 @@ pub(crate) async fn get_message_events_route(
 				.timeline
 				.pdus_after(sender_user, &body.room_id, from)?
 				.filter_map(Result::ok) // Filter out buggy events
-				.filter(|(_, pdu)| contains_url_filter(pdu, &body.filter))
+				.filter(|(_, pdu)| filter.pdu_event_allowed(pdu))
 				.filter(|(_, pdu)| visibility_filter(pdu, sender_user, &body.room_id))
 				.take_while(|&(k, _)| Some(k) != to) // Stop at `to`
 				.take(limit)
@@ -222,7 +221,7 @@ pub(crate) async fn get_message_events_route(
 				.timeline
 				.pdus_until(sender_user, &body.room_id, from)?
 				.filter_map(Result::ok) // Filter out buggy events
-				.filter(|(_, pdu)| contains_url_filter(pdu, &body.filter))
+				.filter(|(_, pdu)| filter.pdu_event_allowed(pdu))
 				.filter(|(_, pdu)| visibility_filter(pdu, sender_user, &body.room_id))
 				.take_while(|&(k, _)| Some(k) != to) // Stop at `to`
 				.take(limit)
@@ -291,16 +290,3 @@ fn visibility_filter(pdu: &PduEvent, user_id: &UserId, room_id: &RoomId) -> bool
 		.user_can_see_event(user_id, room_id, &pdu.event_id)
 		.unwrap_or(false)
 }
-
-fn contains_url_filter(pdu: &PduEvent, filter: &RoomEventFilter) -> bool {
-	if filter.url_filter.is_none() {
-		return true;
-	}
-
-	let content: Value = from_str(pdu.content.get()).unwrap();
-	match filter.url_filter {
-		Some(UrlFilter::EventsWithoutUrl) => !content["url"].is_string(),
-		Some(UrlFilter::EventsWithUrl) => content["url"].is_string(),
-		None => true,
-	}
-}

src/utils/filter.rs

@@ -14,9 +14,12 @@
 
 use std::{collections::HashSet, hash::Hash};
 
-use ruma::{api::client::filter::RoomEventFilter, RoomId};
+use ruma::{
+	api::client::filter::{RoomEventFilter, UrlFilter},
+	RoomId,
+};
 
-use crate::Error;
+use crate::{Error, PduEvent};
 
 /// Structure for testing against an allowlist and a denylist with a single
 /// `HashSet` lookup.
@@ -60,6 +63,7 @@ impl<'a, T: ?Sized + Hash + PartialEq + Eq> AllowDenyList<'a, T> {
 
 pub(crate) struct CompiledRoomEventFilter<'a> {
 	rooms: AllowDenyList<'a, RoomId>,
+	url_filter: Option<UrlFilter>,
 }
 
 impl<'a> TryFrom<&'a RoomEventFilter> for CompiledRoomEventFilter<'a> {
@@ -68,6 +72,7 @@ impl<'a> TryFrom<&'a RoomEventFilter> for CompiledRoomEventFilter<'a> {
 	fn try_from(source: &'a RoomEventFilter) -> Result<CompiledRoomEventFilter<'a>, Error> {
 		Ok(CompiledRoomEventFilter {
 			rooms: AllowDenyList::from_slices(source.rooms.as_deref(), &source.not_rooms),
+			url_filter: source.url_filter,
 		})
 	}
 }
@@ -81,4 +86,26 @@ impl CompiledRoomEventFilter<'_> {
 	/// rejected by the top-level filter using
 	/// [`CompiledRoomFilter::room_allowed`], if applicable.
 	pub(crate) fn room_allowed(&self, room_id: &RoomId) -> bool { self.rooms.allowed(room_id) }
+
+	/// Returns `true` if a PDU event is allowed by the filter.
+	///
+	/// This tests against the `url_filter` field.
+	///
+	/// This does *not* check whether the event's room is allowed. It is
+	/// expected that callers have already filtered out rejected rooms using
+	/// [`CompiledRoomEventFilter::room_allowed`] and
+	/// [`CompiledRoomFilter::room_allowed`].
+	pub(crate) fn pdu_event_allowed(&self, pdu: &PduEvent) -> bool { self.allowed_by_url_filter(pdu) }
+
+	fn allowed_by_url_filter(&self, pdu: &PduEvent) -> bool {
+		let Some(filter) = self.url_filter else {
+			return true;
+		};
+		// TODO: is this unwrap okay?
+		let content: serde_json::Value = serde_json::from_str(pdu.content.get()).unwrap();
+		match filter {
+			UrlFilter::EventsWithoutUrl => !content["url"].is_string(),
+			UrlFilter::EventsWithUrl => content["url"].is_string(),
+		}
+	}
 }