Add support for MSC4155 (#1013)

[rendered msc here](https://github.com/Johennes/matrix-spec-proposals/blob/johannes/invite-filtering/proposals/4155-invite-filtering.md). Closes #836.

Co-authored-by: nexy7574 <git@nexy7574.co.uk>
Reviewed-on: https://forgejo.ellis.link/continuwuation/continuwuity/pulls/1013
Reviewed-by: nex <nex@noreply.forgejo.ellis.link>
Co-authored-by: Ginger <ginger@gingershaped.computer>
Co-committed-by: Ginger <ginger@gingershaped.computer>

src/service/rooms/state_cache/mod.rs

@@ -12,7 +12,7 @@ use conduwuit::{
 use database::{Deserialized, Ignore, Interfix, Map};
 use futures::{Stream, StreamExt, future::join5, pin_mut};
 use ruma::{
-	OwnedRoomId, RoomId, ServerName, UserId,
+	OwnedRoomId, OwnedUserId, RoomId, ServerName, UserId,
 	events::{AnyStrippedStateEvent, AnySyncStateEvent, room::member::MembershipState},
 	serde::Raw,
 };
@@ -49,6 +49,7 @@ struct Data {
 	userroomid_joined: Arc<Map>,
 	userroomid_leftstate: Arc<Map>,
 	userroomid_knockedstate: Arc<Map>,
+	userroomid_invitesender: Arc<Map>,
 }
 
 type AppServiceInRoomCache = SyncRwLock<HashMap<OwnedRoomId, HashMap<String, bool>>>;
@@ -83,6 +84,7 @@ impl crate::Service for Service {
 				userroomid_joined: args.db["userroomid_joined"].clone(),
 				userroomid_leftstate: args.db["userroomid_leftstate"].clone(),
 				userroomid_knockedstate: args.db["userroomid_knockedstate"].clone(),
+				userroomid_invitesender: args.db["userroomid_invitesender"].clone(),
 			},
 		}))
 	}
@@ -523,3 +525,14 @@ pub async fn is_left(&self, user_id: &UserId, room_id: &RoomId) -> bool {
 	let key = (user_id, room_id);
 	self.db.userroomid_leftstate.qry(&key).await.is_ok()
 }
+
+#[implement(Service)]
+#[tracing::instrument(skip(self), level = "trace")]
+pub async fn invite_sender(&self, user_id: &UserId, room_id: &RoomId) -> Result<OwnedUserId> {
+	let key = (user_id, room_id);
+	self.db
+		.userroomid_invitesender
+		.qry(&key)
+		.await
+		.deserialized()
+}

src/service/rooms/state_cache/update.rs

@@ -1,6 +1,6 @@
 use std::collections::HashSet;
 
-use conduwuit::{Result, implement, is_not_empty, utils::ReadyExt, warn};
+use conduwuit::{Err, Result, implement, is_not_empty, utils::ReadyExt, warn};
 use database::{Json, serialize_key};
 use futures::StreamExt;
 use ruma::{
@@ -9,6 +9,7 @@ use ruma::{
 		AnyStrippedStateEvent, AnySyncStateEvent, GlobalAccountDataEventType,
 		RoomAccountDataEventType, StateEventType,
 		direct::DirectEvent,
+		invite_permission_config::FilterLevel,
 		room::{
 			create::RoomCreateEventContent,
 			member::{MembershipState, RoomMemberEventContent},
@@ -121,12 +122,21 @@ pub async fn update_membership(
 			self.mark_as_joined(user_id, room_id);
 		},
 		| MembershipState::Invite => {
-			// We want to know if the sender is ignored by the receiver
-			if self.services.users.user_is_ignored(sender, user_id).await {
-				return Ok(());
+			// return an error for blocked invites. ignored invites aren't handled here
+			// since the recipient's membership should still be changed to `invite`.
+			// they're filtered out in the individual /sync handlers
+			if matches!(
+				self.services
+					.users
+					.invite_filter_level(sender, user_id)
+					.await,
+				FilterLevel::Block
+			) {
+				return Err!(Request(InviteBlocked(
+					"{user_id} has blocked invites from {sender}."
+				)));
 			}
-
-			self.mark_as_invited(user_id, room_id, last_state, invite_via)
+			self.mark_as_invited(user_id, room_id, sender, last_state, invite_via)
 				.await;
 		},
 		| MembershipState::Leave | MembershipState::Ban => {
@@ -231,6 +241,7 @@ pub fn mark_as_joined(&self, user_id: &UserId, room_id: &RoomId) {
 
 	self.db.userroomid_invitestate.remove(&userroom_id);
 	self.db.roomuserid_invitecount.remove(&roomuser_id);
+	self.db.userroomid_invitesender.remove(&userroom_id);
 
 	self.db.userroomid_leftstate.remove(&userroom_id);
 	self.db.roomuserid_leftcount.remove(&roomuser_id);
@@ -268,6 +279,7 @@ pub fn mark_as_left(&self, user_id: &UserId, room_id: &RoomId) {
 
 	self.db.userroomid_invitestate.remove(&userroom_id);
 	self.db.roomuserid_invitecount.remove(&roomuser_id);
+	self.db.userroomid_invitesender.remove(&userroom_id);
 
 	self.db.userroomid_knockedstate.remove(&userroom_id);
 	self.db.roomuserid_knockedcount.remove(&roomuser_id);
@@ -304,6 +316,7 @@ pub fn mark_as_knocked(
 
 	self.db.userroomid_invitestate.remove(&userroom_id);
 	self.db.roomuserid_invitecount.remove(&roomuser_id);
+	self.db.userroomid_invitesender.remove(&userroom_id);
 
 	self.db.userroomid_leftstate.remove(&userroom_id);
 	self.db.roomuserid_leftcount.remove(&roomuser_id);
@@ -335,6 +348,7 @@ pub async fn mark_as_invited(
 	&self,
 	user_id: &UserId,
 	room_id: &RoomId,
+	sender_user: &UserId,
 	last_state: Option<Vec<Raw<AnyStrippedStateEvent>>>,
 	invite_via: Option<Vec<OwnedServerName>>,
 ) {
@@ -350,6 +364,9 @@ pub async fn mark_as_invited(
 	self.db
 		.roomuserid_invitecount
 		.raw_aput::<8, _, _>(&roomuser_id, self.services.globals.next_count().unwrap());
+	self.db
+		.userroomid_invitesender
+		.raw_put(&userroom_id, sender_user);
 
 	self.db.userroomid_joined.remove(&userroom_id);
 	self.db.roomuserid_joined.remove(&roomuser_id);

src/service/users/mod.rs

@@ -20,7 +20,9 @@ use ruma::{
 	api::client::{device::Device, error::ErrorKind, filter::FilterDefinition},
 	encryption::{CrossSigningKey, DeviceKeys, OneTimeKey},
 	events::{
-		AnyToDeviceEvent, GlobalAccountDataEventType, ignored_user_list::IgnoredUserListEvent,
+		AnyToDeviceEvent, GlobalAccountDataEventType,
+		ignored_user_list::IgnoredUserListEvent,
+		invite_permission_config::{FilterLevel, InvitePermissionConfigEvent},
 	},
 	serde::Raw,
 };
@@ -139,6 +141,26 @@ impl Service {
 			})
 	}
 
+	/// Returns the recipient's filter level for an invite from the sender.
+	pub async fn invite_filter_level(
+		&self,
+		sender_user: &UserId,
+		recipient_user: &UserId,
+	) -> FilterLevel {
+		if self.user_is_ignored(sender_user, recipient_user).await {
+			FilterLevel::Ignore
+		} else {
+			self.services
+				.account_data
+				.get_global(recipient_user, GlobalAccountDataEventType::InvitePermissionConfig)
+				.await
+				.map(|config: InvitePermissionConfigEvent| {
+					config.content.user_filter_level(sender_user)
+				})
+				.unwrap_or(FilterLevel::Allow)
+		}
+	}
+
 	/// Check if a user is an admin
 	#[inline]
 	pub async fn is_admin(&self, user_id: &UserId) -> bool {