Key Backups (3/3) : Implement querying keys and various bugfixes (#1946)

* Add querying device keys

Makes a bunch of sytests pass

* Apparently only the current version supports uploading keys

* Linting

clientapi/routing/key_backup.go

@@ -37,7 +37,7 @@ type keyBackupVersionCreateResponse struct {
 type keyBackupVersionResponse struct {
 	Algorithm string          `json:"algorithm"`
 	AuthData  json.RawMessage `json:"auth_data"`
-	Count     int             `json:"count"`
+	Count     int64           `json:"count"`
 	ETag      string          `json:"etag"`
 	Version   string          `json:"version"`
 }
@@ -89,7 +89,10 @@ func CreateKeyBackupVersion(req *http.Request, userAPI userapi.UserInternalAPI,
 // Implements GET  /_matrix/client/r0/room_keys/version and GET /_matrix/client/r0/room_keys/version/{version}
 func KeyBackupVersion(req *http.Request, userAPI userapi.UserInternalAPI, device *userapi.Device, version string) util.JSONResponse {
 	var queryResp userapi.QueryKeyBackupResponse
-	userAPI.QueryKeyBackup(req.Context(), &userapi.QueryKeyBackupRequest{}, &queryResp)
+	userAPI.QueryKeyBackup(req.Context(), &userapi.QueryKeyBackupRequest{
+		UserID:  device.UserID,
+		Version: version,
+	}, &queryResp)
 	if queryResp.Error != "" {
 		return util.ErrorResponse(fmt.Errorf("QueryKeyBackup: %s", queryResp.Error))
 	}
@@ -216,3 +219,73 @@ func UploadBackupKeys(
 		},
 	}
 }
+
+// Get keys from a given backup version. Response returned varies depending on if roomID and sessionID are set.
+func GetBackupKeys(
+	req *http.Request, userAPI userapi.UserInternalAPI, device *userapi.Device, version, roomID, sessionID string,
+) util.JSONResponse {
+	var queryResp userapi.QueryKeyBackupResponse
+	userAPI.QueryKeyBackup(req.Context(), &userapi.QueryKeyBackupRequest{
+		UserID:           device.UserID,
+		Version:          version,
+		ReturnKeys:       true,
+		KeysForRoomID:    roomID,
+		KeysForSessionID: sessionID,
+	}, &queryResp)
+	if queryResp.Error != "" {
+		return util.ErrorResponse(fmt.Errorf("QueryKeyBackup: %s", queryResp.Error))
+	}
+	if !queryResp.Exists {
+		return util.JSONResponse{
+			Code: 404,
+			JSON: jsonerror.NotFound("version not found"),
+		}
+	}
+	if sessionID != "" {
+		// return the key itself if it was found
+		roomData, ok := queryResp.Keys[roomID]
+		if ok {
+			key, ok := roomData[sessionID]
+			if ok {
+				return util.JSONResponse{
+					Code: 200,
+					JSON: key,
+				}
+			}
+		}
+	} else if roomID != "" {
+		roomData, ok := queryResp.Keys[roomID]
+		if ok {
+			// wrap response in "sessions"
+			return util.JSONResponse{
+				Code: 200,
+				JSON: struct {
+					Sessions map[string]userapi.KeyBackupSession `json:"sessions"`
+				}{
+					Sessions: roomData,
+				},
+			}
+		}
+	} else {
+		// response is the same as the upload request
+		var resp keyBackupSessionRequest
+		resp.Rooms = make(map[string]struct {
+			Sessions map[string]userapi.KeyBackupSession `json:"sessions"`
+		})
+		for roomID, roomData := range queryResp.Keys {
+			resp.Rooms[roomID] = struct {
+				Sessions map[string]userapi.KeyBackupSession `json:"sessions"`
+			}{
+				Sessions: roomData,
+			}
+		}
+		return util.JSONResponse{
+			Code: 200,
+			JSON: resp,
+		}
+	}
+	return util.JSONResponse{
+		Code: 404,
+		JSON: jsonerror.NotFound("keys not found"),
+	}
+}

clientapi/routing/routing.go

@@ -896,11 +896,15 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	// Key Backup Versions
-	r0mux.Handle("/room_keys/version/{versionID}",
+	// Key Backup Versions (Metadata)
+
+	r0mux.Handle("/room_keys/version/{version}",
 		httputil.MakeAuthAPI("get_backup_keys_version", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
-			version := req.URL.Query().Get("version")
-			return KeyBackupVersion(req, userAPI, device, version)
+			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
+			return KeyBackupVersion(req, userAPI, device, vars["version"])
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 	r0mux.Handle("/room_keys/version",
@@ -908,28 +912,22 @@ func Setup(
 			return KeyBackupVersion(req, userAPI, device, "")
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
-	r0mux.Handle("/room_keys/version/{versionID}",
+	r0mux.Handle("/room_keys/version/{version}",
 		httputil.MakeAuthAPI("put_backup_keys_version", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
-			version := req.URL.Query().Get("version")
-			if version == "" {
-				return util.JSONResponse{
-					Code: 400,
-					JSON: jsonerror.InvalidArgumentValue("version must be specified"),
+			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
 			}
-			}
-			return ModifyKeyBackupVersionAuthData(req, userAPI, device, version)
+			return ModifyKeyBackupVersionAuthData(req, userAPI, device, vars["version"])
 		}),
 	).Methods(http.MethodPut)
-	r0mux.Handle("/room_keys/version/{versionID}",
+	r0mux.Handle("/room_keys/version/{version}",
 		httputil.MakeAuthAPI("delete_backup_keys_version", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
-			version := req.URL.Query().Get("version")
-			if version == "" {
-				return util.JSONResponse{
-					Code: 400,
-					JSON: jsonerror.InvalidArgumentValue("version must be specified"),
+			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
 			}
-			}
-			return DeleteKeyBackupVersion(req, userAPI, device, version)
+			return DeleteKeyBackupVersion(req, userAPI, device, vars["version"])
 		}),
 	).Methods(http.MethodDelete)
 	r0mux.Handle("/room_keys/version",
@@ -938,7 +936,8 @@ func Setup(
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	// E2E Backup Keys
+	// Inserting E2E Backup Keys
+
 	// Bulk room and session
 	r0mux.Handle("/room_keys/keys",
 		httputil.MakeAuthAPI("put_backup_keys", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
@@ -973,6 +972,9 @@ func Setup(
 			}
 			roomID := vars["roomID"]
 			var reqBody keyBackupSessionRequest
+			reqBody.Rooms = make(map[string]struct {
+				Sessions map[string]userapi.KeyBackupSession `json:"sessions"`
+			})
 			reqBody.Rooms[roomID] = struct {
 				Sessions map[string]userapi.KeyBackupSession `json:"sessions"`
 			}{
@@ -989,7 +991,7 @@ func Setup(
 	).Methods(http.MethodPut)
 	// Single room, single session
 	r0mux.Handle("/room_keys/keys/{roomID}/{sessionID}",
-		httputil.MakeAuthAPI("put_backup_keys_room", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+		httputil.MakeAuthAPI("put_backup_keys_room_session", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
 				return util.ErrorResponse(err)
@@ -1009,14 +1011,47 @@ func Setup(
 			roomID := vars["roomID"]
 			sessionID := vars["sessionID"]
 			var keyReq keyBackupSessionRequest
+			keyReq.Rooms = make(map[string]struct {
+				Sessions map[string]userapi.KeyBackupSession `json:"sessions"`
+			})
 			keyReq.Rooms[roomID] = struct {
 				Sessions map[string]userapi.KeyBackupSession `json:"sessions"`
-			}{}
+			}{
+				Sessions: make(map[string]userapi.KeyBackupSession),
+			}
 			keyReq.Rooms[roomID].Sessions[sessionID] = reqBody
 			return UploadBackupKeys(req, userAPI, device, version, &keyReq)
 		}),
 	).Methods(http.MethodPut)
 
+	// Querying E2E Backup Keys
+
+	r0mux.Handle("/room_keys/keys",
+		httputil.MakeAuthAPI("get_backup_keys", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+			return GetBackupKeys(req, userAPI, device, req.URL.Query().Get("version"), "", "")
+		}),
+	).Methods(http.MethodGet, http.MethodOptions)
+	r0mux.Handle("/room_keys/keys/{roomID}",
+		httputil.MakeAuthAPI("get_backup_keys_room", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
+			return GetBackupKeys(req, userAPI, device, req.URL.Query().Get("version"), vars["roomID"], "")
+		}),
+	).Methods(http.MethodGet, http.MethodOptions)
+	r0mux.Handle("/room_keys/keys/{roomID}/{sessionID}",
+		httputil.MakeAuthAPI("get_backup_keys_room_session", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
+			return GetBackupKeys(req, userAPI, device, req.URL.Query().Get("version"), vars["roomID"], vars["sessionID"])
+		}),
+	).Methods(http.MethodGet, http.MethodOptions)
+
+	// Deleting E2E Backup Keys
+
 	// Supplying a device ID is deprecated.
 	r0mux.Handle("/keys/upload/{deviceID}",
 		httputil.MakeAuthAPI("keys_upload", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {

sytest-whitelist

@@ -540,3 +540,13 @@ Key notary server must not overwrite a valid key with a spurious result from the
 GET /rooms/:room_id/aliases lists aliases
 Only room members can list aliases of a room
 Users with sufficient power-level can delete other's aliases
+Can create backup version
+Can update backup version
+Responds correctly when backup is empty
+Can backup keys
+Can update keys with better versions
+Will not update keys with worse versions
+Will not back up to an old backup version
+Can create more than 10 backup versions
+Can delete backup
+Deleted & recreated backups are empty

userapi/api/api.go

@@ -67,6 +67,23 @@ type KeyBackupSession struct {
 	SessionData       json.RawMessage `json:"session_data"`
 }
 
+func (a *KeyBackupSession) ShouldReplaceRoomKey(newKey *KeyBackupSession) bool {
+	// https://spec.matrix.org/unstable/client-server-api/#backup-algorithm-mmegolm_backupv1curve25519-aes-sha2
+	// "if the keys have different values for is_verified, then it will keep the key that has is_verified set to true"
+	if newKey.IsVerified && !a.IsVerified {
+		return true
+	}
+	// "if they have the same values for is_verified, then it will keep the key with a lower first_message_index"
+	if newKey.FirstMessageIndex < a.FirstMessageIndex {
+		return true
+	}
+	// "and finally, is is_verified and first_message_index are equal, then it will keep the key with a lower forwarded_count"
+	if newKey.ForwardedCount < a.ForwardedCount {
+		return true
+	}
+	return false
+}
+
 // Internal KeyBackupData for passing to/from the storage layer
 type InternalKeyBackupSession struct {
 	KeyBackupSession
@@ -88,6 +105,10 @@ type PerformKeyBackupResponse struct {
 type QueryKeyBackupRequest struct {
 	UserID  string
 	Version string // the version to query, if blank it means the latest
+
+	ReturnKeys       bool   // whether to return keys in the backup response or just the metadata
+	KeysForRoomID    string // optional string to return keys which belong to this room
+	KeysForSessionID string // optional string to return keys which belong to this (room, session)
 }
 
 type QueryKeyBackupResponse struct {
@@ -96,9 +117,11 @@ type QueryKeyBackupResponse struct {
 
 	Algorithm string          `json:"algorithm"`
 	AuthData  json.RawMessage `json:"auth_data"`
-	Count     int             `json:"count"`
+	Count     int64           `json:"count"`
 	ETag      string          `json:"etag"`
 	Version   string          `json:"version"`
+
+	Keys map[string]map[string]KeyBackupSession // the keys if ReturnKeys=true
 }
 
 // InputAccountDataRequest is the request for InputAccountData

userapi/internal/api.go

@@ -475,6 +475,7 @@ func (a *UserInternalAPI) PerformKeyBackup(ctx context.Context, req *api.Perform
 		if err != nil {
 			res.Error = fmt.Sprintf("failed to update backup: %s", err)
 		}
+		res.Exists = err == nil
 		res.Version = req.Version
 		return
 	}
@@ -483,8 +484,8 @@ func (a *UserInternalAPI) PerformKeyBackup(ctx context.Context, req *api.Perform
 }
 
 func (a *UserInternalAPI) uploadBackupKeys(ctx context.Context, req *api.PerformKeyBackupRequest, res *api.PerformKeyBackupResponse) {
-	// ensure the version metadata exists
-	version, _, _, _, deleted, err := a.AccountDB.GetKeyBackup(ctx, req.UserID, req.Version)
+	// you can only upload keys for the CURRENT version
+	version, _, _, _, deleted, err := a.AccountDB.GetKeyBackup(ctx, req.UserID, "")
 	if err != nil {
 		res.Error = fmt.Sprintf("failed to query version: %s", err)
 		return
@@ -493,6 +494,11 @@ func (a *UserInternalAPI) uploadBackupKeys(ctx context.Context, req *api.Perform
 		res.Error = "backup was deleted"
 		return
 	}
+	if version != req.Version {
+		res.BadInput = true
+		res.Error = fmt.Sprintf("%s isn't the current version, %s is.", req.Version, version)
+		return
+	}
 	res.Exists = true
 	res.Version = version
 
@@ -529,9 +535,21 @@ func (a *UserInternalAPI) QueryKeyBackup(ctx context.Context, req *api.QueryKeyB
 	}
 	res.Algorithm = algorithm
 	res.AuthData = authData
+	res.ETag = etag
 	res.Exists = !deleted
 
-	// TODO:
-	res.Count = 0
-	res.ETag = etag
+	if !req.ReturnKeys {
+		res.Count, err = a.AccountDB.CountBackupKeys(ctx, version, req.UserID)
+		if err != nil {
+			res.Error = fmt.Sprintf("failed to count keys: %s", err)
+		}
+		return
+	}
+
+	result, err := a.AccountDB.GetBackupKeys(ctx, version, req.UserID, req.KeysForRoomID, req.KeysForSessionID)
+	if err != nil {
+		res.Error = fmt.Sprintf("failed to query keys: %s", err)
+		return
+	}
+	res.Keys = result
 }

userapi/storage/accounts/interface.go

@@ -61,6 +61,8 @@ type Database interface {
 	DeleteKeyBackup(ctx context.Context, userID, version string) (exists bool, err error)
 	GetKeyBackup(ctx context.Context, userID, version string) (versionResult, algorithm string, authData json.RawMessage, etag string, deleted bool, err error)
 	UpsertBackupKeys(ctx context.Context, version, userID string, uploads []api.InternalKeyBackupSession) (count int64, etag string, err error)
+	GetBackupKeys(ctx context.Context, version, userID, filterRoomID, filterSessionID string) (result map[string]map[string]api.KeyBackupSession, err error)
+	CountBackupKeys(ctx context.Context, version, userID string) (count int64, err error)
 }
 
 // Err3PIDInUse is the error returned when trying to save an association involving

userapi/storage/accounts/postgres/key_backup_table.go

@@ -35,7 +35,8 @@ CREATE TABLE IF NOT EXISTS account_e2e_room_keys (
     is_verified BOOLEAN NOT NULL,
     session_data TEXT NOT NULL
 );
-CREATE UNIQUE INDEX IF NOT EXISTS e2e_room_keys_idx ON account_e2e_room_keys(user_id, room_id, session_id);
+CREATE UNIQUE INDEX IF NOT EXISTS e2e_room_keys_idx ON account_e2e_room_keys(user_id, room_id, session_id, version);
+CREATE UNIQUE INDEX IF NOT EXISTS e2e_room_keys_versions_idx ON account_e2e_room_keys(user_id, version);
 `
 
 const insertBackupKeySQL = "" +
@@ -53,14 +54,23 @@ const selectKeysSQL = "" +
 	"SELECT room_id, session_id, first_message_index, forwarded_count, is_verified, session_data FROM account_e2e_room_keys " +
 	"WHERE user_id = $1 AND version = $2"
 
+const selectKeysByRoomIDSQL = "" +
+	"SELECT room_id, session_id, first_message_index, forwarded_count, is_verified, session_data FROM account_e2e_room_keys " +
+	"WHERE user_id = $1 AND version = $2 AND room_id = $3"
+
+const selectKeysByRoomIDAndSessionIDSQL = "" +
+	"SELECT room_id, session_id, first_message_index, forwarded_count, is_verified, session_data FROM account_e2e_room_keys " +
+	"WHERE user_id = $1 AND version = $2 AND room_id = $3 AND session_id = $4"
+
 type keyBackupStatements struct {
 	insertBackupKeyStmt                *sql.Stmt
 	updateBackupKeyStmt                *sql.Stmt
 	countKeysStmt                      *sql.Stmt
 	selectKeysStmt                     *sql.Stmt
+	selectKeysByRoomIDStmt             *sql.Stmt
+	selectKeysByRoomIDAndSessionIDStmt *sql.Stmt
 }
 
-// nolint:unused
 func (s *keyBackupStatements) prepare(db *sql.DB) (err error) {
 	_, err = db.Exec(keyBackupTableSchema)
 	if err != nil {
@@ -78,6 +88,12 @@ func (s *keyBackupStatements) prepare(db *sql.DB) (err error) {
 	if s.selectKeysStmt, err = db.Prepare(selectKeysSQL); err != nil {
 		return
 	}
+	if s.selectKeysByRoomIDStmt, err = db.Prepare(selectKeysByRoomIDSQL); err != nil {
+		return
+	}
+	if s.selectKeysByRoomIDAndSessionIDStmt, err = db.Prepare(selectKeysByRoomIDAndSessionIDSQL); err != nil {
+		return
+	}
 	return
 }
 
@@ -109,11 +125,35 @@ func (s *keyBackupStatements) updateBackupKey(
 func (s *keyBackupStatements) selectKeys(
 	ctx context.Context, txn *sql.Tx, userID, version string,
 ) (map[string]map[string]api.KeyBackupSession, error) {
-	result := make(map[string]map[string]api.KeyBackupSession)
 	rows, err := txn.Stmt(s.selectKeysStmt).QueryContext(ctx, userID, version)
 	if err != nil {
 		return nil, err
 	}
+	return unpackKeys(ctx, rows)
+}
+
+func (s *keyBackupStatements) selectKeysByRoomID(
+	ctx context.Context, txn *sql.Tx, userID, version, roomID string,
+) (map[string]map[string]api.KeyBackupSession, error) {
+	rows, err := txn.Stmt(s.selectKeysByRoomIDStmt).QueryContext(ctx, userID, version, roomID)
+	if err != nil {
+		return nil, err
+	}
+	return unpackKeys(ctx, rows)
+}
+
+func (s *keyBackupStatements) selectKeysByRoomIDAndSessionID(
+	ctx context.Context, txn *sql.Tx, userID, version, roomID, sessionID string,
+) (map[string]map[string]api.KeyBackupSession, error) {
+	rows, err := txn.Stmt(s.selectKeysByRoomIDAndSessionIDStmt).QueryContext(ctx, userID, version, roomID, sessionID)
+	if err != nil {
+		return nil, err
+	}
+	return unpackKeys(ctx, rows)
+}
+
+func unpackKeys(ctx context.Context, rows *sql.Rows) (map[string]map[string]api.KeyBackupSession, error) {
+	result := make(map[string]map[string]api.KeyBackupSession)
 	defer internal.CloseAndLogIfError(ctx, rows, "selectKeysStmt.Close failed")
 	for rows.Next() {
 		var key api.InternalKeyBackupSession

userapi/storage/accounts/postgres/key_backup_version_table.go

@@ -67,7 +67,6 @@ type keyBackupVersionStatements struct {
 	updateKeyBackupETagStmt     *sql.Stmt
 }
 
-// nolint:unused
 func (s *keyBackupVersionStatements) prepare(db *sql.DB) (err error) {
 	_, err = db.Exec(keyBackupVersionTableSchema)
 	if err != nil {

userapi/storage/accounts/postgres/storage.go

@@ -96,13 +96,12 @@ func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserver
 	if err = d.openIDTokens.prepare(db, serverName); err != nil {
 		return nil, err
 	}
-	/*
 	if err = d.keyBackupVersions.prepare(db); err != nil {
 		return nil, err
 	}
 	if err = d.keyBackups.prepare(db); err != nil {
 		return nil, err
-		} */
+	}
 
 	return d, nil
 }
@@ -418,6 +417,37 @@ func (d *Database) GetKeyBackup(
 	return
 }
 
+func (d *Database) GetBackupKeys(
+	ctx context.Context, version, userID, filterRoomID, filterSessionID string,
+) (result map[string]map[string]api.KeyBackupSession, err error) {
+	err = sqlutil.WithTransaction(d.db, func(txn *sql.Tx) error {
+		if filterSessionID != "" {
+			result, err = d.keyBackups.selectKeysByRoomIDAndSessionID(ctx, txn, userID, version, filterRoomID, filterSessionID)
+			return err
+		}
+		if filterRoomID != "" {
+			result, err = d.keyBackups.selectKeysByRoomID(ctx, txn, userID, version, filterRoomID)
+			return err
+		}
+		result, err = d.keyBackups.selectKeys(ctx, txn, userID, version)
+		return err
+	})
+	return
+}
+
+func (d *Database) CountBackupKeys(
+	ctx context.Context, version, userID string,
+) (count int64, err error) {
+	err = sqlutil.WithTransaction(d.db, func(txn *sql.Tx) error {
+		count, err = d.keyBackups.countKeys(ctx, txn, userID, version)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	return
+}
+
 // nolint:nakedret
 func (d *Database) UpsertBackupKeys(
 	ctx context.Context, version, userID string, uploads []api.InternalKeyBackupSession,
@@ -445,7 +475,7 @@ func (d *Database) UpsertBackupKeys(
 			if existingRoom != nil {
 				existingSession, ok := existingRoom[newKey.SessionID]
 				if ok {
-					if shouldReplaceRoomKey(existingSession, newKey.KeyBackupSession) {
+					if existingSession.ShouldReplaceRoomKey(&newKey.KeyBackupSession) {
 						err = d.keyBackups.updateBackupKey(ctx, txn, userID, version, newKey)
 						changed = true
 						if err != nil {
@@ -489,22 +519,3 @@ func (d *Database) UpsertBackupKeys(
 	})
 	return
 }
-
-// TODO FIXME XXX : This logic really shouldn't live in the storage layer, but I don't know where else is sensible which won't
-// create circular import loops
-func shouldReplaceRoomKey(existing, uploaded api.KeyBackupSession) bool {
-	// https://spec.matrix.org/unstable/client-server-api/#backup-algorithm-mmegolm_backupv1curve25519-aes-sha2
-	// "if the keys have different values for is_verified, then it will keep the key that has is_verified set to true"
-	if uploaded.IsVerified && !existing.IsVerified {
-		return true
-	}
-	// "if they have the same values for is_verified, then it will keep the key with a lower first_message_index"
-	if uploaded.FirstMessageIndex < existing.FirstMessageIndex {
-		return true
-	}
-	// "and finally, is is_verified and first_message_index are equal, then it will keep the key with a lower forwarded_count"
-	if uploaded.ForwardedCount < existing.ForwardedCount {
-		return true
-	}
-	return false
-}

userapi/storage/accounts/sqlite3/key_backup_table.go

@@ -35,7 +35,8 @@ CREATE TABLE IF NOT EXISTS account_e2e_room_keys (
     is_verified BOOLEAN NOT NULL,
     session_data TEXT NOT NULL
 );
-CREATE UNIQUE INDEX IF NOT EXISTS e2e_room_keys_idx ON account_e2e_room_keys(user_id, room_id, session_id);
+CREATE UNIQUE INDEX IF NOT EXISTS e2e_room_keys_idx ON account_e2e_room_keys(user_id, room_id, session_id, version);
+CREATE UNIQUE INDEX IF NOT EXISTS e2e_room_keys_versions_idx ON account_e2e_room_keys(user_id, version);
 `
 
 const insertBackupKeySQL = "" +
@@ -53,14 +54,23 @@ const selectKeysSQL = "" +
 	"SELECT room_id, session_id, first_message_index, forwarded_count, is_verified, session_data FROM account_e2e_room_keys " +
 	"WHERE user_id = $1 AND version = $2"
 
+const selectKeysByRoomIDSQL = "" +
+	"SELECT room_id, session_id, first_message_index, forwarded_count, is_verified, session_data FROM account_e2e_room_keys " +
+	"WHERE user_id = $1 AND version = $2 AND room_id = $3"
+
+const selectKeysByRoomIDAndSessionIDSQL = "" +
+	"SELECT room_id, session_id, first_message_index, forwarded_count, is_verified, session_data FROM account_e2e_room_keys " +
+	"WHERE user_id = $1 AND version = $2 AND room_id = $3 AND session_id = $4"
+
 type keyBackupStatements struct {
 	insertBackupKeyStmt                *sql.Stmt
 	updateBackupKeyStmt                *sql.Stmt
 	countKeysStmt                      *sql.Stmt
 	selectKeysStmt                     *sql.Stmt
+	selectKeysByRoomIDStmt             *sql.Stmt
+	selectKeysByRoomIDAndSessionIDStmt *sql.Stmt
 }
 
-// nolint:unused
 func (s *keyBackupStatements) prepare(db *sql.DB) (err error) {
 	_, err = db.Exec(keyBackupTableSchema)
 	if err != nil {
@@ -78,6 +88,12 @@ func (s *keyBackupStatements) prepare(db *sql.DB) (err error) {
 	if s.selectKeysStmt, err = db.Prepare(selectKeysSQL); err != nil {
 		return
 	}
+	if s.selectKeysByRoomIDStmt, err = db.Prepare(selectKeysByRoomIDSQL); err != nil {
+		return
+	}
+	if s.selectKeysByRoomIDAndSessionIDStmt, err = db.Prepare(selectKeysByRoomIDAndSessionIDSQL); err != nil {
+		return
+	}
 	return
 }
 
@@ -109,11 +125,35 @@ func (s *keyBackupStatements) updateBackupKey(
 func (s *keyBackupStatements) selectKeys(
 	ctx context.Context, txn *sql.Tx, userID, version string,
 ) (map[string]map[string]api.KeyBackupSession, error) {
-	result := make(map[string]map[string]api.KeyBackupSession)
 	rows, err := txn.Stmt(s.selectKeysStmt).QueryContext(ctx, userID, version)
 	if err != nil {
 		return nil, err
 	}
+	return unpackKeys(ctx, rows)
+}
+
+func (s *keyBackupStatements) selectKeysByRoomID(
+	ctx context.Context, txn *sql.Tx, userID, version, roomID string,
+) (map[string]map[string]api.KeyBackupSession, error) {
+	rows, err := txn.Stmt(s.selectKeysByRoomIDStmt).QueryContext(ctx, userID, version, roomID)
+	if err != nil {
+		return nil, err
+	}
+	return unpackKeys(ctx, rows)
+}
+
+func (s *keyBackupStatements) selectKeysByRoomIDAndSessionID(
+	ctx context.Context, txn *sql.Tx, userID, version, roomID, sessionID string,
+) (map[string]map[string]api.KeyBackupSession, error) {
+	rows, err := txn.Stmt(s.selectKeysByRoomIDAndSessionIDStmt).QueryContext(ctx, userID, version, roomID, sessionID)
+	if err != nil {
+		return nil, err
+	}
+	return unpackKeys(ctx, rows)
+}
+
+func unpackKeys(ctx context.Context, rows *sql.Rows) (map[string]map[string]api.KeyBackupSession, error) {
+	result := make(map[string]map[string]api.KeyBackupSession)
 	defer internal.CloseAndLogIfError(ctx, rows, "selectKeysStmt.Close failed")
 	for rows.Next() {
 		var key api.InternalKeyBackupSession

userapi/storage/accounts/sqlite3/key_backup_version_table.go

@@ -65,7 +65,6 @@ type keyBackupVersionStatements struct {
 	updateKeyBackupETagStmt     *sql.Stmt
 }
 
-// nolint:unused
 func (s *keyBackupVersionStatements) prepare(db *sql.DB) (err error) {
 	_, err = db.Exec(keyBackupVersionTableSchema)
 	if err != nil {

userapi/storage/accounts/sqlite3/storage.go

@@ -100,13 +100,12 @@ func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserver
 	if err = d.openIDTokens.prepare(db, serverName); err != nil {
 		return nil, err
 	}
-	/*
 	if err = d.keyBackupVersions.prepare(db); err != nil {
 		return nil, err
 	}
 	if err = d.keyBackups.prepare(db); err != nil {
 		return nil, err
-		} */
+	}
 
 	return d, nil
 }
@@ -459,6 +458,37 @@ func (d *Database) GetKeyBackup(
 	return
 }
 
+func (d *Database) GetBackupKeys(
+	ctx context.Context, version, userID, filterRoomID, filterSessionID string,
+) (result map[string]map[string]api.KeyBackupSession, err error) {
+	err = d.writer.Do(d.db, nil, func(txn *sql.Tx) error {
+		if filterSessionID != "" {
+			result, err = d.keyBackups.selectKeysByRoomIDAndSessionID(ctx, txn, userID, version, filterRoomID, filterSessionID)
+			return err
+		}
+		if filterRoomID != "" {
+			result, err = d.keyBackups.selectKeysByRoomID(ctx, txn, userID, version, filterRoomID)
+			return err
+		}
+		result, err = d.keyBackups.selectKeys(ctx, txn, userID, version)
+		return err
+	})
+	return
+}
+
+func (d *Database) CountBackupKeys(
+	ctx context.Context, version, userID string,
+) (count int64, err error) {
+	err = d.writer.Do(d.db, nil, func(txn *sql.Tx) error {
+		count, err = d.keyBackups.countKeys(ctx, txn, userID, version)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	return
+}
+
 // nolint:nakedret
 func (d *Database) UpsertBackupKeys(
 	ctx context.Context, version, userID string, uploads []api.InternalKeyBackupSession,
@@ -486,7 +516,7 @@ func (d *Database) UpsertBackupKeys(
 			if existingRoom != nil {
 				existingSession, ok := existingRoom[newKey.SessionID]
 				if ok {
-					if shouldReplaceRoomKey(existingSession, newKey.KeyBackupSession) {
+					if existingSession.ShouldReplaceRoomKey(&newKey.KeyBackupSession) {
 						err = d.keyBackups.updateBackupKey(ctx, txn, userID, version, newKey)
 						changed = true
 						if err != nil {
@@ -531,22 +561,3 @@ func (d *Database) UpsertBackupKeys(
 	})
 	return
 }
-
-// TODO FIXME XXX : This logic really shouldn't live in the storage layer, but I don't know where else is sensible which won't
-// create circular import loops
-func shouldReplaceRoomKey(existing, uploaded api.KeyBackupSession) bool {
-	// https://spec.matrix.org/unstable/client-server-api/#backup-algorithm-mmegolm_backupv1curve25519-aes-sha2
-	// "if the keys have different values for is_verified, then it will keep the key that has is_verified set to true"
-	if uploaded.IsVerified && !existing.IsVerified {
-		return true
-	}
-	// "if they have the same values for is_verified, then it will keep the key with a lower first_message_index"
-	if uploaded.FirstMessageIndex < existing.FirstMessageIndex {
-		return true
-	}
-	// "and finally, is is_verified and first_message_index are equal, then it will keep the key with a lower forwarded_count"
-	if uploaded.ForwardedCount < existing.ForwardedCount {
-		return true
-	}
-	return false
-}