Room version abstractions (#865)

* Rough first pass at adding room version abstractions

* Define newer room versions

* Update room version metadata

* Fix roomserver/versions

* Try to fix whitespace in roomsSchema

roomserver/version/version.go

@@ -0,0 +1,94 @@
+package version
+
+import (
+	"errors"
+
+	"github.com/matrix-org/dendrite/roomserver/state"
+)
+
+type RoomVersionID int
+type EventFormatID int
+
+const (
+	RoomVersionV1 RoomVersionID = iota + 1
+	RoomVersionV2
+	RoomVersionV3
+	RoomVersionV4
+	RoomVersionV5
+)
+
+const (
+	EventFormatV1 EventFormatID = iota + 1 // original event ID formatting
+	EventFormatV2                          // event ID is event hash
+	EventFormatV3                          // event ID is URL-safe base64 event hash
+)
+
+type RoomVersionDescription struct {
+	Supported                 bool
+	Stable                    bool
+	StateResolution           state.StateResolutionVersion
+	EventFormat               EventFormatID
+	EnforceSigningKeyValidity bool
+}
+
+var roomVersions = map[RoomVersionID]RoomVersionDescription{
+	RoomVersionV1: RoomVersionDescription{
+		Supported:                 true,
+		Stable:                    true,
+		StateResolution:           state.StateResolutionAlgorithmV1,
+		EventFormat:               EventFormatV1,
+		EnforceSigningKeyValidity: false,
+	},
+	RoomVersionV2: RoomVersionDescription{
+		Supported:                 false,
+		Stable:                    true,
+		StateResolution:           state.StateResolutionAlgorithmV2,
+		EventFormat:               EventFormatV1,
+		EnforceSigningKeyValidity: false,
+	},
+	RoomVersionV3: RoomVersionDescription{
+		Supported:                 false,
+		Stable:                    true,
+		StateResolution:           state.StateResolutionAlgorithmV2,
+		EventFormat:               EventFormatV2,
+		EnforceSigningKeyValidity: false,
+	},
+	RoomVersionV4: RoomVersionDescription{
+		Supported:                 false,
+		Stable:                    true,
+		StateResolution:           state.StateResolutionAlgorithmV2,
+		EventFormat:               EventFormatV3,
+		EnforceSigningKeyValidity: false,
+	},
+	RoomVersionV5: RoomVersionDescription{
+		Supported:                 false,
+		Stable:                    true,
+		StateResolution:           state.StateResolutionAlgorithmV2,
+		EventFormat:               EventFormatV3,
+		EnforceSigningKeyValidity: true,
+	},
+}
+
+func GetRoomVersions() map[RoomVersionID]RoomVersionDescription {
+	return roomVersions
+}
+
+func GetSupportedRoomVersions() map[RoomVersionID]RoomVersionDescription {
+	versions := make(map[RoomVersionID]RoomVersionDescription)
+	for id, version := range GetRoomVersions() {
+		if version.Supported {
+			versions[id] = version
+		}
+	}
+	return versions
+}
+
+func GetSupportedRoomVersion(version RoomVersionID) (desc RoomVersionDescription, err error) {
+	if version, ok := roomVersions[version]; ok {
+		desc = version
+	}
+	if !desc.Supported {
+		err = errors.New("unsupported room version")
+	}
+	return
+}