Store & retrieve filters as structs rather than []byte (#436)

Manipulate filters as gomatrix.Filter structures, instead of their []byte JSON representation.
This lays ground work for using filters in dendrite for /sync requests.

clientapi/auth/storage/accounts/filter_table.go

@@ -17,6 +17,7 @@ package accounts
 import (
 	"context"
 	"database/sql"
+	"encoding/json"
 
 	"github.com/matrix-org/gomatrixserverlib"
 )
@@ -71,25 +72,44 @@ func (s *filterStatements) prepare(db *sql.DB) (err error) {
 
 func (s *filterStatements) selectFilter(
 	ctx context.Context, localpart string, filterID string,
-) (filter []byte, err error) {
-	err = s.selectFilterStmt.QueryRowContext(ctx, localpart, filterID).Scan(&filter)
-	return
+) (*gomatrixserverlib.Filter, error) {
+	// Retrieve filter from database (stored as canonical JSON)
+	var filterData []byte
+	err := s.selectFilterStmt.QueryRowContext(ctx, localpart, filterID).Scan(&filterData)
+	if err != nil {
+		return nil, err
+	}
+
+	// Unmarshal JSON into Filter struct
+	var filter gomatrixserverlib.Filter
+	if err = json.Unmarshal(filterData, &filter); err != nil {
+		return nil, err
+	}
+	return &filter, nil
 }
 
 func (s *filterStatements) insertFilter(
-	ctx context.Context, filter []byte, localpart string,
+	ctx context.Context, filter *gomatrixserverlib.Filter, localpart string,
 ) (filterID string, err error) {
 	var existingFilterID string
 
-	// This can result in a race condition when two clients try to insert the
-	// same filter and localpart at the same time, however this is not a
-	// problem as both calls will result in the same filterID
-	filterJSON, err := gomatrixserverlib.CanonicalJSON(filter)
+	// Serialise json
+	filterJSON, err := json.Marshal(filter)
+	if err != nil {
+		return "", err
+	}
+	// Remove whitespaces and sort JSON data
+	// needed to prevent from inserting the same filter multiple times
+	filterJSON, err = gomatrixserverlib.CanonicalJSON(filterJSON)
 	if err != nil {
 		return "", err
 	}
 
-	// Check if filter already exists in the database
+	// Check if filter already exists in the database using its localpart and content
+	//
+	// This can result in a race condition when two clients try to insert the
+	// same filter and localpart at the same time, however this is not a
+	// problem as both calls will result in the same filterID
 	err = s.selectFilterIDByContentStmt.QueryRowContext(ctx,
 		localpart, filterJSON).Scan(&existingFilterID)
 	if err != nil && err != sql.ErrNoRows {

clientapi/auth/storage/accounts/storage.go

@@ -344,11 +344,11 @@ func (d *Database) GetThreePIDsForLocalpart(
 }
 
 // GetFilter looks up the filter associated with a given local user and filter ID.
-// Returns a filter represented as a byte slice. Otherwise returns an error if
-// no such filter exists or if there was an error talking to the database.
+// Returns a filter structure. Otherwise returns an error if no such filter exists
+// or if there was an error talking to the database.
 func (d *Database) GetFilter(
 	ctx context.Context, localpart string, filterID string,
-) ([]byte, error) {
+) (*gomatrixserverlib.Filter, error) {
 	return d.filter.selectFilter(ctx, localpart, filterID)
 }
 
@@ -356,7 +356,7 @@ func (d *Database) GetFilter(
 // Returns the filterID as a string. Otherwise returns an error if something
 // goes wrong.
 func (d *Database) PutFilter(
-	ctx context.Context, localpart string, filter []byte,
+	ctx context.Context, localpart string, filter *gomatrixserverlib.Filter,
 ) (string, error) {
 	return d.filter.insertFilter(ctx, filter, localpart)
 }

clientapi/routing/filter.go

@@ -17,13 +17,10 @@ package routing
 import (
 	"net/http"
 
-	"encoding/json"
-
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/dendrite/clientapi/auth/storage/accounts"
 	"github.com/matrix-org/dendrite/clientapi/httputil"
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
-	"github.com/matrix-org/gomatrix"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
 )
@@ -43,7 +40,7 @@ func GetFilter(
 		return httputil.LogThenError(req, err)
 	}
 
-	res, err := accountDB.GetFilter(req.Context(), localpart, filterID)
+	filter, err := accountDB.GetFilter(req.Context(), localpart, filterID)
 	if err != nil {
 		//TODO better error handling. This error message is *probably* right,
 		// but if there are obscure db errors, this will also be returned,
@@ -53,11 +50,6 @@ func GetFilter(
 			JSON: jsonerror.NotFound("No such filter"),
 		}
 	}
-	filter := gomatrix.Filter{}
-	err = json.Unmarshal(res, &filter)
-	if err != nil {
-		return httputil.LogThenError(req, err)
-	}
 
 	return util.JSONResponse{
 		Code: http.StatusOK,
@@ -85,21 +77,21 @@ func PutFilter(
 		return httputil.LogThenError(req, err)
 	}
 
-	var filter gomatrix.Filter
+	var filter gomatrixserverlib.Filter
 
 	if reqErr := httputil.UnmarshalJSONRequest(req, &filter); reqErr != nil {
 		return *reqErr
 	}
 
-	filterArray, err := json.Marshal(filter)
-	if err != nil {
+	// Validate generates a user-friendly error
+	if err = filter.Validate(); err != nil {
 		return util.JSONResponse{
 			Code: http.StatusBadRequest,
-			JSON: jsonerror.BadJSON("Filter is malformed"),
+			JSON: jsonerror.BadJSON("Invalid filter: " + err.Error()),
 		}
 	}
 
-	filterID, err := accountDB.PutFilter(req.Context(), localpart, filterArray)
+	filterID, err := accountDB.PutFilter(req.Context(), localpart, &filter)
 	if err != nil {
 		return httputil.LogThenError(req, err)
 	}