feat: Give send_knock the invite treatment

src/api/server/invite.rs

@@ -23,7 +23,7 @@
 };
 use serde::Deserialize;
 
-use crate::Ruma;
+use crate::{Ruma, server::utils::validate_any_membership_event};
 
 /// # `PUT /_matrix/federation/v2/invite/{roomId}/{eventId}`
 ///
@@ -86,7 +86,7 @@ pub(crate) async fn create_invite_route(
 	}
 
 	// And then we can validate the member event itself
-	let (mut signed_event, sender_user, recipient_user) = validate_membership_event(
+	let (mut signed_event, sender_user, recipient_user) = validate_invite_membership_event(
 		&services,
 		&body.event,
 		&room_version_rules,
@@ -234,7 +234,7 @@ pub(crate) async fn create_invite_route(
 /// invite event itself.
 ///
 /// [spec]: https://spec.matrix.org/v1.19/server-server-api/#put_matrixfederationv2inviteroomideventid
-async fn validate_membership_event(
+async fn validate_invite_membership_event(
 	services: &crate::State,
 	body: &serde_json::value::RawValue,
 	room_version_rules: &RoomVersionRules,
@@ -243,80 +243,22 @@ async fn validate_membership_event(
 	room_id: OwnedRoomId,
 	event_id: OwnedEventId,
 ) -> Result<(CanonicalJsonObject, OwnedUserId, OwnedUserId)> {
-	let (template_room_id, template_event_id, pdu) = services
-		.rooms
-		.event_handler
-		.parse_incoming_pdu(body)
-		.await
-		.map_err(|e| err!(Request(BadJson("Invalid invite event PDU: {e}"))))?;
-
-	if template_room_id != room_id {
-		return Err!(Request(InvalidParam("Membership event does not belong to requested room")));
-	}
-	if template_event_id != event_id {
-		return Err!(Request(InvalidParam(
-			"Membership event ID does not match provided event ID"
-		)));
-	}
-
-	services
-		.server_keys
-		.verify_event(&pdu, room_version_rules)
-		.await
-		.map_err(|e| {
-			err!(Request(InvalidParam("Signature verification failed on invite event: {e}")))
-		})?;
-
-	// Ensure this is a membership event
-	if pdu
-		.get("type")
-		.expect("event must have a type")
-		.as_str()
-		.expect("type must be a string")
-		!= "m.room.member"
-	{
-		return Err!(Request(BadJson(
-			"Not allowed to send non-membership event to invite endpoint"
-		)));
-	}
-
-	// Ensure it is an invite event
-	// My Huge Chain (avoids deser)
-	let membership = pdu
-		.get("content")
-		.ok_or_else(|| err!(Request(BadJson("Event missing content property"))))?
-		.as_object()
-		.ok_or_else(|| err!(Request(BadJson("Event content is not an object"))))?
-		.get("membership")
-		.ok_or_else(|| err!(Request(BadJson("Event missing membership property"))))?
-		.as_str()
-		.ok_or_else(|| err!(Request(BadJson("Event is not a string"))))?;
-	if MembershipState::Invite != membership.into() {
-		return Err!(Request(BadJson(
-			"Not allowed to send non-invite membership event to invite endpoint"
-		)));
-	}
+	let (pdu, target_membership, sender_user, recipient_user) = validate_any_membership_event(
+		services,
+		body,
+		room_version_rules,
+		create_event_id,
+		room_id,
+		event_id,
+	)
+	.await?;
 
 	// Ensure the sender belongs to the remote that is sending the invite
-	let sender_user = pdu
-		.get("sender")
-		.and_then(|v| v.as_str())
-		.map(UserId::parse)
-		.and_then(Result::ok)
-		.ok_or_else(|| err!(Request(InvalidParam("Invalid sender property"))))?;
-
 	if sender_user.server_name() != origin {
 		return Err!(Request(Forbidden("Sender belongs to a different server")));
 	}
 
 	// Ensure the target user belongs to this server
-	let recipient_user = pdu
-		.get("state_key")
-		.and_then(|v| v.as_str())
-		.map(UserId::parse)
-		.and_then(Result::ok)
-		.ok_or_else(|| err!(Request(InvalidParam("Invalid state_key property"))))?;
-
 	if !services
 		.globals
 		.server_is_ours(recipient_user.server_name())
@@ -324,18 +266,9 @@ async fn validate_membership_event(
 		return Err!(Request(InvalidParam("Recipient does not belong to this homeserver")));
 	}
 
-	// Do a quick format check. The spec doesn't suggest this, but it's probably
-	// a good idea nonetheless.
-	service::rooms::event_handler::Service::pdu_format_check_1(
-		&pdu,
-		room_version_rules,
-		&create_event_id,
-	)
-	.map_err(|e| {
-		err!(Request(InvalidParam(
-			"Invite membership event violates the room event format: {e}"
-		)))
-	})?;
+	if target_membership != MembershipState::Invite {
+		return Err!(Request(BadJson("Invalid membership (expected `invite`)")));
+	}
 
 	Ok((pdu, sender_user, recipient_user))
 }

src/api/server/send_knock.rs

@@ -1,21 +1,11 @@
 use axum::extract::State;
-use conduwuit::{
-	Err, Result, err, info,
-	matrix::{event::gen_event_id_canonical_json, pdu::PduEvent},
-	warn,
-};
+use conduwuit::{Err, Event, Result, debug_info, err, matrix::pdu::PduEvent, warn};
 use futures::FutureExt;
 use ruma::{
-	OwnedUserId,
-	api::federation::membership::create_knock_event,
-	events::{
-		StateEventType,
-		room::member::{MembershipState, RoomMemberEventContent},
-	},
-	serde::JsonObject,
+	api::federation::membership::create_knock_event, events::room::member::MembershipState,
 };
 
-use crate::Ruma;
+use crate::{Ruma, server::utils::validate_any_membership_event};
 
 /// # `PUT /_matrix/federation/v1/send_knock/{roomId}/{eventId}`
 ///
@@ -33,18 +23,7 @@ pub(crate) async fn create_knock_event_v1_route(
 			 forbidden. Rejecting.",
 			body.identity, &body.room_id,
 		);
-		return Err!(Request(Forbidden("Server is banned on this homeserver.")));
-	}
-
-	if let Some(server) = body.room_id.server_name() {
-		if services.moderation.is_remote_server_forbidden(server) {
-			warn!(
-				"Server {} tried knocking room ID {} which has a server name that is globally \
-				 forbidden. Rejecting.",
-				body.identity, &body.room_id,
-			);
-			return Err!(Request(Forbidden("Server is banned on this homeserver.")));
-		}
+		return Err!(Request(Forbidden("Federation denied with {}", body.identity)));
 	}
 
 	if !services.rooms.metadata.exists(&body.room_id).await {
@@ -57,8 +36,9 @@ pub(crate) async fn create_knock_event_v1_route(
 		.server_in_room(services.globals.server_name(), &body.room_id)
 		.await
 	{
-		info!(
+		debug_info!(
 			origin = body.identity.as_str(),
+			room_id = %body.room_id,
 			"Refusing to serve send_knock for room we aren't participating in"
 		);
 		return Err!(Request(NotFound("This server is not participating in that room.")));
@@ -72,88 +52,40 @@ pub(crate) async fn create_knock_event_v1_route(
 		.await?;
 
 	let room_version = services.rooms.state.get_room_version(&body.room_id).await?;
+	let create_event = services
+		.rooms
+		.state_accessor
+		.get_room_create_event(&body.room_id)
+		.await;
 	let room_version_rules = room_version.rules().unwrap();
 
 	if !room_version_rules.authorization.knocking {
 		return Err!(Request(Forbidden("Room version does not support knocking.")));
 	}
 
-	let Ok((event_id, value)) = gen_event_id_canonical_json(&body.pdu, &room_version_rules)
-	else {
-		// Event could not be converted to canonical json
-		return Err!(Request(InvalidParam("Could not convert event to canonical json.")));
-	};
-
-	let event_type: StateEventType = serde_json::from_value(
-		value
-			.get("type")
-			.ok_or_else(|| err!(Request(InvalidParam("Event has no event type."))))?
-			.clone()
-			.into(),
+	let (mut event, target_membership, sender, target) = validate_any_membership_event(
+		&services,
+		&body.pdu,
+		&room_version_rules,
+		create_event.event_id().to_owned(),
+		body.room_id.clone(),
+		body.event_id.clone(),
 	)
-	.map_err(|e| err!(Request(InvalidParam("Event has invalid event type: {e}"))))?;
+	.await?;
 
-	if event_type != StateEventType::RoomMember {
-		return Err!(Request(InvalidParam(
-			"Not allowed to send non-membership state event to knock endpoint.",
-		)));
+	if target_membership != MembershipState::Knock {
+		return Err!(Request(InvalidParam("Invalid membership (expected `knock`)")));
 	}
-
-	let content: RoomMemberEventContent = serde_json::from_value(
-		value
-			.get("content")
-			.ok_or_else(|| err!(Request(InvalidParam("Membership event has no content"))))?
-			.clone()
-			.into(),
-	)
-	.map_err(|e| err!(Request(InvalidParam("Event has invalid membership content: {e}"))))?;
-
-	if content.membership != MembershipState::Knock {
-		return Err!(Request(InvalidParam(
-			"Not allowed to send a non-knock membership event to knock endpoint."
-		)));
-	}
-
-	// ACL check sender server name
-	let sender: OwnedUserId = serde_json::from_value(
-		value
-			.get("sender")
-			.ok_or_else(|| err!(Request(InvalidParam("Event has no sender user ID."))))?
-			.clone()
-			.into(),
-	)
-	.map_err(|e| err!(Request(BadJson("Event sender is not a valid user ID: {e}"))))?;
-
-	services
-		.rooms
-		.event_handler
-		.acl_check(sender.server_name(), &body.room_id)
-		.await?;
-
-	// check if origin server is trying to send for another server
 	if sender.server_name() != body.identity {
-		return Err!(Request(BadJson("Not allowed to knock on behalf of another server/user.")));
+		return Err!(Request(InvalidParam("Sender belongs to a different server")));
+	}
+	if sender != target {
+		return Err!(Request(InvalidParam("Sender does not match state key")));
 	}
 
-	let state_key: OwnedUserId = serde_json::from_value(
-		value
-			.get("state_key")
-			.ok_or_else(|| err!(Request(InvalidParam("Event does not have a state_key"))))?
-			.clone()
-			.into(),
-	)
-	.map_err(|e| err!(Request(BadJson("Event does not have a valid state_key: {e}"))))?;
+	event.insert("event_id".to_owned(), body.event_id.as_str().into());
 
-	if state_key != sender {
-		return Err!(Request(InvalidParam("state_key does not match sender user of event.")));
-	}
-
-	let mut event: JsonObject = serde_json::from_str(body.pdu.get())
-		.map_err(|e| err!(Request(InvalidParam("Invalid knock event PDU: {e}"))))?;
-
-	event.insert("event_id".to_owned(), "$placeholder".into());
-
-	let pdu: PduEvent = serde_json::from_value(event.into())
+	let pdu = PduEvent::from_id_val(&body.event_id, event.clone())
 		.map_err(|e| err!(Request(InvalidParam("Invalid knock event PDU: {e}"))))?;
 
 	let mutex_lock = services
@@ -166,7 +98,7 @@ pub(crate) async fn create_knock_event_v1_route(
 	let pdu_id = services
 		.rooms
 		.event_handler
-		.handle_incoming_pdu(sender.server_name(), &body.room_id, &event_id, value.clone(), false)
+		.handle_incoming_pdu(sender.server_name(), &body.room_id, &body.event_id, event, false)
 		.boxed()
 		.await?
 		.ok_or_else(|| err!(Request(InvalidParam("Could not accept as timeline event."))))?;

src/api/server/utils.rs

@@ -1,7 +1,10 @@
-use conduwuit::{Err, Result, is_false};
+use conduwuit::{Err, Result, err, is_false};
 use conduwuit_service::Services;
 use futures::{FutureExt, future::OptionFuture, join};
-use ruma::{EventId, RoomId, ServerName};
+use ruma::{
+	CanonicalJsonObject, EventId, OwnedEventId, OwnedRoomId, OwnedUserId, RoomId, ServerName,
+	UserId, events::room::member::MembershipState, room_version_rules::RoomVersionRules,
+};
 
 pub(super) struct AccessCheck<'a> {
 	pub(super) services: &'a Services,
@@ -63,3 +66,101 @@ pub(super) async fn assert(&self) -> Result {
 		Ok(())
 	}
 }
+
+/// Performs validation on a membership event that should be run on any event a
+/// remote is trying to send via us.
+///
+/// ## Checks performed
+///
+/// 1. PDU room ID matches request path room ID
+/// 2. PDU event ID matches request path event ID
+/// 3. Signature check
+/// 4. Event type check
+/// 5. `sender` field presence (and parsing)
+/// 6. `state_key` field presence (and parsing)
+/// 7. PDU room format check (PDU check 1)
+///
+/// ## Returns
+///
+/// A resulting tuple of (PDU JSON, target membership state, sender, recipient).
+pub(crate) async fn validate_any_membership_event(
+	services: &crate::State,
+	body: &serde_json::value::RawValue,
+	room_version_rules: &RoomVersionRules,
+	create_event_id: OwnedEventId,
+	expected_room_id: OwnedRoomId,
+	expected_event_id: OwnedEventId,
+) -> Result<(CanonicalJsonObject, MembershipState, OwnedUserId, OwnedUserId)> {
+	let (template_room_id, template_event_id, pdu) = services
+		.rooms
+		.event_handler
+		.parse_incoming_pdu(body)
+		.await
+		.map_err(|e| err!(Request(BadJson("Invalid membership PDU: {e}"))))?;
+
+	if template_room_id != expected_room_id {
+		return Err!(Request(InvalidParam("Membership event does not belong to requested room")));
+	}
+	if template_event_id != expected_event_id {
+		return Err!(Request(InvalidParam(
+			"Membership event ID does not match provided event ID"
+		)));
+	}
+
+	services
+		.server_keys
+		.verify_event(&pdu, room_version_rules)
+		.await
+		.map_err(|e| {
+			err!(Request(InvalidParam("Signature verification failed on membership event: {e}")))
+		})?;
+
+	// Ensure this is a membership event
+	if pdu
+		.get("type")
+		.expect("event must have a type")
+		.as_str()
+		.expect("type must be a string")
+		!= "m.room.member"
+	{
+		return Err!(Request(BadJson(
+			"Not allowed to send non-membership event to this endpoint"
+		)));
+	}
+	let membership = pdu
+		.get("content")
+		.ok_or_else(|| err!(Request(BadJson("Event missing content property"))))?
+		.as_object()
+		.ok_or_else(|| err!(Request(BadJson("Event content is not an object"))))?
+		.get("membership")
+		.ok_or_else(|| err!(Request(BadJson("Event missing membership property"))))?
+		.as_str()
+		.ok_or_else(|| err!(Request(BadJson("Event is not a string"))))?
+		.to_owned();
+
+	let sender_user = pdu
+		.get("sender")
+		.and_then(|v| v.as_str())
+		.map(UserId::parse)
+		.and_then(Result::ok)
+		.ok_or_else(|| err!(Request(InvalidParam("Invalid sender property"))))?;
+	let recipient_user = pdu
+		.get("state_key")
+		.and_then(|v| v.as_str())
+		.map(UserId::parse)
+		.and_then(Result::ok)
+		.ok_or_else(|| err!(Request(InvalidParam("Invalid state_key property"))))?;
+
+	// Do a quick format check. The spec doesn't suggest this, but it's probably
+	// a good idea nonetheless.
+	service::rooms::event_handler::Service::pdu_format_check_1(
+		&pdu,
+		room_version_rules,
+		&create_event_id,
+	)
+	.map_err(|e| {
+		err!(Request(InvalidParam("Membership event violates the room event format: {e}")))
+	})?;
+
+	Ok((pdu, membership.into(), sender_user, recipient_user))
+}