feat(policy-server): Policy server following

src/service/rooms/event_handler/call_policyserv.rs

@@ -0,0 +1,71 @@
+use conduwuit::{
+	Err, Event, PduEvent, Result, debug, implement, utils::to_canonical_object, warn,
+};
+use ruma::{
+	RoomId, ServerName,
+	api::federation::room::policy::v1::Request as PolicyRequest,
+	canonical_json::to_canonical_value,
+	events::{StateEventType, room::policy::RoomPolicyEventContent},
+};
+
+/// Returns Ok if the policy server allows the event
+#[implement(super::Service)]
+#[tracing::instrument(skip_all, level = "debug")]
+pub async fn policyserv_check(&self, pdu: &PduEvent, room_id: &RoomId) -> Result {
+	let Ok(policyserver) = self
+		.services
+		.state_accessor
+		.room_state_get_content(room_id, &StateEventType::RoomPolicy, "")
+		.await
+		.map(|c: RoomPolicyEventContent| c)
+	else {
+		return Ok(());
+	};
+
+	let via = match policyserver.via {
+		| Some(ref via) => ServerName::parse(via)?,
+		| None => {
+			debug!("No policy server configured for room {room_id}");
+			return Ok(());
+		},
+	};
+	// TODO: dont do *this*
+	let pdu_json = self.services.timeline.get_pdu_json(pdu.event_id()).await?;
+	let outgoing = self
+		.services
+		.sending
+		.convert_to_outgoing_federation_event(pdu_json)
+		.await;
+	// let s = match serde_json::to_string(outgoing.as_ref()) {
+	// 	| Ok(s) => s,
+	// 	| Err(e) => {
+	// 		warn!("Failed to convert pdu {} to outgoing federation event: {e}",
+	// pdu.event_id()); 		return Err!(Request(InvalidParam("Failed to convert PDU
+	// to outgoing event."))); 	},
+	// };
+	debug!("Checking pdu {outgoing:?} for spam with policy server {via} for room {room_id}");
+	let response = self
+		.services
+		.sending
+		.send_federation_request(via, PolicyRequest {
+			event_id: pdu.event_id().to_owned(),
+			pdu: Some(outgoing),
+		})
+		.await;
+	let response = match response {
+		| Ok(response) => response,
+		| Err(e) => {
+			warn!("Failed to contact policy server {via} for room {room_id}: {e}");
+			return Ok(());
+		},
+	};
+	if response.recommendation == "spam" {
+		warn!(
+			"Event {} in room {room_id} was marked as spam by policy server {via}",
+			pdu.event_id().to_owned()
+		);
+		return Err!(Request(Forbidden("Event was marked as spam by policy server")));
+	};
+
+	Ok(())
+}