feat(spaces): hierarchy over federation

fix(spaces): deal with hierarchy recursion
fix(spaces): properly handle max_depth
refactor(spaces): token scheme to prevent clients from modifying max_depth and suggested_only
perf(spaces): use tokens to skip to room to start populating results at
feat(spaces): request hierarchy from servers in via field of child event

src/api/client_server/space.rs

@@ -1,5 +1,10 @@
-use crate::{services, Result, Ruma};
-use ruma::api::client::space::get_hierarchy;
+use std::str::FromStr;
+
+use crate::{service::rooms::spaces::PagnationToken, services, Error, Result, Ruma};
+use ruma::{
+    api::client::{error::ErrorKind, space::get_hierarchy},
+    UInt,
+};
 
 /// # `GET /_matrix/client/v1/rooms/{room_id}/hierarchy``
 ///
@@ -9,25 +14,42 @@ pub async fn get_hierarchy_route(
 ) -> Result<get_hierarchy::v1::Response> {
     let sender_user = body.sender_user.as_ref().expect("user is authenticated");
 
-    let skip = body
+    let limit = body
+        .limit
+        .unwrap_or(UInt::from(10_u32))
+        .min(UInt::from(100_u32));
+    let max_depth = body
+        .max_depth
+        .unwrap_or(UInt::from(3_u32))
+        .min(UInt::from(10_u32));
+
+    let key = body
         .from
         .as_ref()
-        .and_then(|s| s.parse::<usize>().ok())
-        .unwrap_or(0);
+        .and_then(|s| PagnationToken::from_str(s).ok());
 
-    let limit = body.limit.map_or(10, u64::from).min(100) as usize;
-
-    let max_depth = body.max_depth.map_or(3, u64::from).min(10) as usize + 1; // +1 to skip the space room itself
+    // Should prevent unexpected behaviour in (bad) clients
+    if let Some(token) = &key {
+        if token.suggested_only != body.suggested_only || token.max_depth != max_depth {
+            return Err(Error::BadRequest(
+                ErrorKind::InvalidParam,
+                "suggested_only and max_depth cannot change on paginated requests",
+            ));
+        }
+    }
 
     services()
         .rooms
         .spaces
-        .get_hierarchy(
+        .get_client_hierarchy(
             sender_user,
             &body.room_id,
-            limit,
-            skip,
-            max_depth,
+            usize::try_from(limit)
+                .map_err(|_| Error::BadRequest(ErrorKind::InvalidParam, "Limit is too great"))?,
+            key.map_or(vec![], |token| token.short_room_ids),
+            usize::try_from(max_depth).map_err(|_| {
+                Error::BadRequest(ErrorKind::InvalidParam, "Max depth is too great")
+            })?,
             body.suggested_only,
         )
         .await

src/api/server_server.rs

@@ -34,6 +34,7 @@ use ruma::{
             membership::{create_invite, create_join_event, prepare_join_event},
             openid::get_openid_userinfo,
             query::{get_profile_information, get_room_information},
+            space::get_hierarchy,
             transactions::{
                 edu::{DeviceListUpdateContent, DirectDeviceContent, Edu, SigningKeyUpdateContent},
                 send_transaction_message,
@@ -2162,6 +2163,31 @@ pub async fn get_openid_userinfo_route(
     ))
 }
 
+/// # `GET /_matrix/federation/v1/hierarchy/{roomId}`
+///
+/// Gets the space tree in a depth-first manner to locate child rooms of a given space.
+pub async fn get_hierarchy_route(
+    body: Ruma<get_hierarchy::v1::Request>,
+) -> Result<get_hierarchy::v1::Response> {
+    let sender_servername = body
+        .sender_servername
+        .as_ref()
+        .expect("server is authenticated");
+
+    if services().rooms.metadata.exists(&body.room_id)? {
+        services()
+            .rooms
+            .spaces
+            .get_federation_hierarchy(&body.room_id, sender_servername, body.suggested_only)
+            .await
+    } else {
+        Err(Error::BadRequest(
+            ErrorKind::NotFound,
+            "Room does not exist.",
+        ))
+    }
+}
+
 /// # `GET /.well-known/matrix/server`
 ///
 /// Returns the federation server discovery information.

src/main.rs

@@ -451,6 +451,7 @@ fn routes(config: &Config) -> Router {
             .ruma_route(server_server::get_keys_route)
             .ruma_route(server_server::claim_keys_route)
             .ruma_route(server_server::get_openid_userinfo_route)
+            .ruma_route(server_server::get_hierarchy_route)
             .ruma_route(server_server::well_known_server)
     } else {
         router

src/service/mod.rs

@@ -105,7 +105,7 @@ impl Services {
                 },
                 threads: rooms::threads::Service { db },
                 spaces: rooms::spaces::Service {
-                    roomid_spacechunk_cache: Mutex::new(LruCache::new(200)),
+                    roomid_spacehierarchy_cache: Mutex::new(LruCache::new(200)),
                 },
                 user: rooms::user::Service { db },
             },
@@ -154,7 +154,13 @@ impl Services {
             .lock()
             .await
             .len();
-        let roomid_spacechunk_cache = self.rooms.spaces.roomid_spacechunk_cache.lock().await.len();
+        let roomid_spacehierarchy_cache = self
+            .rooms
+            .spaces
+            .roomid_spacehierarchy_cache
+            .lock()
+            .await
+            .len();
 
         format!(
             "\
@@ -163,7 +169,7 @@ server_visibility_cache: {server_visibility_cache}
 user_visibility_cache: {user_visibility_cache}
 stateinfo_cache: {stateinfo_cache}
 lasttimelinecount_cache: {lasttimelinecount_cache}
-roomid_spacechunk_cache: {roomid_spacechunk_cache}\
+roomid_spacechunk_cache: {roomid_spacehierarchy_cache}\
             "
         )
     }
@@ -211,7 +217,7 @@ roomid_spacechunk_cache: {roomid_spacechunk_cache}\
         if amount > 5 {
             self.rooms
                 .spaces
-                .roomid_spacechunk_cache
+                .roomid_spacehierarchy_cache
                 .lock()
                 .await
                 .clear();

src/service/rooms/state/mod.rs

@@ -93,7 +93,7 @@ impl Service {
                     services()
                         .rooms
                         .spaces
-                        .roomid_spacechunk_cache
+                        .roomid_spacehierarchy_cache
                         .lock()
                         .await
                         .remove(&pdu.room_id);

src/service/rooms/state_accessor/mod.rs

@@ -10,15 +10,18 @@ use ruma::{
     events::{
         room::{
             avatar::RoomAvatarEventContent,
+            guest_access::{GuestAccess, RoomGuestAccessEventContent},
             history_visibility::{HistoryVisibility, RoomHistoryVisibilityEventContent},
+            join_rules::{AllowRule, JoinRule, RoomJoinRulesEventContent, RoomMembership},
             member::{MembershipState, RoomMemberEventContent},
             name::RoomNameEventContent,
             power_levels::{RoomPowerLevels, RoomPowerLevelsEventContent},
         },
         StateEventType,
     },
+    space::SpaceRoomJoinRule,
     state_res::Event,
-    EventId, JsOption, OwnedServerName, OwnedUserId, RoomId, ServerName, UserId,
+    EventId, JsOption, OwnedRoomId, OwnedServerName, OwnedUserId, RoomId, ServerName, UserId,
 };
 use serde_json::value::to_raw_value;
 use tokio::sync::MutexGuard;
@@ -396,4 +399,70 @@ impl Service {
                 }
             })
     }
+
+    /// Checks if guests are able to join a given room
+    pub fn guest_can_join(&self, room_id: &RoomId) -> Result<bool, Error> {
+        self.room_state_get(room_id, &StateEventType::RoomGuestAccess, "")?
+            .map_or(Ok(false), |s| {
+                serde_json::from_str(s.content.get())
+                    .map(|c: RoomGuestAccessEventContent| c.guest_access == GuestAccess::CanJoin)
+                    .map_err(|_| {
+                        Error::bad_database("Invalid room guest access event in database.")
+                    })
+            })
+    }
+
+    /// Checks if guests are able to view room content without joining
+    pub fn world_readable(&self, room_id: &RoomId) -> Result<bool, Error> {
+        self.room_state_get(room_id, &StateEventType::RoomHistoryVisibility, "")?
+            .map_or(Ok(false), |s| {
+                serde_json::from_str(s.content.get())
+                    .map(|c: RoomHistoryVisibilityEventContent| {
+                        c.history_visibility == HistoryVisibility::WorldReadable
+                    })
+                    .map_err(|_| {
+                        Error::bad_database("Invalid room history visibility event in database.")
+                    })
+            })
+    }
+
+    /// Returns the join rule for a given room
+    pub fn get_join_rule(
+        &self,
+        current_room: &RoomId,
+    ) -> Result<(SpaceRoomJoinRule, Vec<OwnedRoomId>), Error> {
+        Ok(self
+            .room_state_get(current_room, &StateEventType::RoomJoinRules, "")?
+            .map(|s| {
+                serde_json::from_str(s.content.get())
+                    .map(|c: RoomJoinRulesEventContent| {
+                        (
+                            c.join_rule.clone().into(),
+                            self.allowed_room_ids(c.join_rule),
+                        )
+                    })
+                    .map_err(|e| {
+                        error!("Invalid room join rule event in database: {}", e);
+                        Error::BadDatabase("Invalid room join rule event in database.")
+                    })
+            })
+            .transpose()?
+            .unwrap_or((SpaceRoomJoinRule::Invite, vec![])))
+    }
+
+    /// Returns an empty vec if not a restricted room
+    pub fn allowed_room_ids(&self, join_rule: JoinRule) -> Vec<OwnedRoomId> {
+        let mut room_ids = vec![];
+        if let JoinRule::Restricted(r) | JoinRule::KnockRestricted(r) = join_rule {
+            for rule in r.allow {
+                if let AllowRule::RoomMembership(RoomMembership {
+                    room_id: membership,
+                }) = rule
+                {
+                    room_ids.push(membership.to_owned());
+                }
+            }
+        }
+        room_ids
+    }
 }

src/service/rooms/state_cache/mod.rs

@@ -248,11 +248,13 @@ impl Service {
         self.db.room_members(room_id)
     }
 
+    /// Returns the number of users which are currently in a room
     #[tracing::instrument(skip(self))]
     pub fn room_joined_count(&self, room_id: &RoomId) -> Result<Option<u64>> {
         self.db.room_joined_count(room_id)
     }
 
+    /// Returns the number of users which are currently invited to a room
     #[tracing::instrument(skip(self))]
     pub fn room_invited_count(&self, room_id: &RoomId) -> Result<Option<u64>> {
         self.db.room_invited_count(room_id)

src/service/rooms/timeline/mod.rs

@@ -430,7 +430,7 @@ impl Service {
                     services()
                         .rooms
                         .spaces
-                        .roomid_spacechunk_cache
+                        .roomid_spacehierarchy_cache
                         .lock()
                         .await
                         .remove(&pdu.room_id);