fix room version comparisons

Fixes a set of bugs introduced by 00b77144c1,
where we replaced explicit `RoomVersionId` matches with `version < V11`
comparisons. The `Ord` impl on `RoomVersionId` does not work like that,
and is in fact a lexicographic string comparison[1]. The most visible
effect of these bugs is that incoming redaction events would sometimes
be ignored.

Instead of reverting to the explicit matches, which were quite verbose,
I implemented a `RoomVersion` struct that has flags for each property
that we care about. This is similar to the approach used by ruma[2] and
synapse[3].

[1]: 7cfa3be0c6/crates/ruma-common/src/identifiers/room_version_id.rs (L136)
[2]: 7cfa3be0c6/crates/ruma-state-res/src/room_version.rs
[3]: c856ae4724/synapse/api/room_versions.py

src/service/rooms/event_handler.rs

@@ -27,7 +27,7 @@ use ruma::{
         StateEventType, TimelineEventType,
     },
     int,
-    state_res::{self, RoomVersion, StateMap},
+    state_res::{self, StateMap},
     uint, CanonicalJsonObject, CanonicalJsonValue, EventId,
     MilliSecondsSinceUnixEpoch, OwnedServerName, OwnedServerSigningKeyId,
     RoomId, RoomVersionId, ServerName,
@@ -44,7 +44,7 @@ use super::{
 use crate::{
     service::{globals::SigningKeys, pdu},
     services,
-    utils::debug_slice_truncated,
+    utils::{debug_slice_truncated, room_version::RoomVersion},
     Error, PduEvent, Result,
 };
 
@@ -339,8 +339,10 @@ impl Service {
                 )?;
 
             let room_version_id = &create_event_content.room_version;
-            let room_version = RoomVersion::new(room_version_id)
-                .expect("room version is supported");
+            let ruma_room_version =
+                state_res::RoomVersion::new(room_version_id).map_err(|_| {
+                    Error::UnsupportedRoomVersion(room_version_id.clone())
+                })?;
 
             // TODO: For RoomVersion6 we must check that Raw<..> is canonical,
             // do we anywhere?
@@ -527,7 +529,7 @@ impl Service {
             }
 
             if !state_res::event_auth::auth_check(
-                &room_version,
+                &ruma_room_version,
                 &incoming_pdu,
                 // TODO: third party invite
                 None::<PduEvent>,
@@ -601,8 +603,11 @@ impl Service {
             )?;
 
         let room_version_id = &create_event_content.room_version;
-        let room_version = RoomVersion::new(room_version_id)
-            .expect("room version is supported");
+        let room_version = RoomVersion::try_from(room_version_id)?;
+        let ruma_room_version = state_res::RoomVersion::new(room_version_id)
+            .map_err(|_| {
+                Error::UnsupportedRoomVersion(room_version_id.clone())
+            })?;
 
         // 10. Fetch missing state and auth chain events by calling /state_ids
         //     at backwards extremities doing all the checks in this list
@@ -885,7 +890,7 @@ impl Service {
         // 11. Check the auth of the event passes based on the state of the
         //     event
         let check_result = state_res::event_auth::auth_check(
-            &room_version,
+            &ruma_room_version,
             &incoming_pdu,
             // TODO: third party invite
             None::<PduEvent>,
@@ -930,7 +935,7 @@ impl Service {
         )?;
 
         let soft_fail = !state_res::event_auth::auth_check(
-            &room_version,
+            &ruma_room_version,
             &incoming_pdu,
             None::<PduEvent>,
             |k, s| auth_events.get(&(k.clone(), s.to_owned())),
@@ -939,45 +944,34 @@ impl Service {
             Error::BadRequest(ErrorKind::InvalidParam, "Auth check failed.")
         })? || incoming_pdu.kind
             == TimelineEventType::RoomRedaction
-            && match room_version_id {
-                room_version if *room_version < RoomVersionId::V11 => {
-                    if let Some(redact_id) = &incoming_pdu.redacts {
-                        !services().rooms.state_accessor.user_can_redact(
-                            redact_id,
-                            &incoming_pdu.sender,
-                            &incoming_pdu.room_id,
-                            true,
-                        )?
-                    } else {
-                        false
-                    }
-                }
-                RoomVersionId::V11 => {
-                    let content = serde_json::from_str::<
-                        RoomRedactionEventContent,
-                    >(
-                        incoming_pdu.content.get()
+            && if room_version.redaction_event_redacts_in_content {
+                let content =
+                    serde_json::from_str::<RoomRedactionEventContent>(
+                        incoming_pdu.content.get(),
                     )
                     .map_err(|_| {
                         Error::bad_database("Invalid content in redaction pdu.")
                     })?;
 
-                    if let Some(redact_id) = &content.redacts {
-                        !services().rooms.state_accessor.user_can_redact(
-                            redact_id,
-                            &incoming_pdu.sender,
-                            &incoming_pdu.room_id,
-                            true,
-                        )?
-                    } else {
-                        false
-                    }
-                }
-                _ => {
-                    return Err(Error::BadServerResponse(
-                        "Unsupported room version.",
-                    ))
+                if let Some(redact_id) = &content.redacts {
+                    !services().rooms.state_accessor.user_can_redact(
+                        redact_id,
+                        &incoming_pdu.sender,
+                        &incoming_pdu.room_id,
+                        true,
+                    )?
+                } else {
+                    false
                 }
+            } else if let Some(redact_id) = &incoming_pdu.redacts {
+                !services().rooms.state_accessor.user_can_redact(
+                    redact_id,
+                    &incoming_pdu.sender,
+                    &incoming_pdu.room_id,
+                    true,
+                )?
+            } else {
+                false
             };
 
         // 13. Use state resolution to find new room state