Rate limit Web Push checks

No need to re-check that a Web Push subscription is valid every
time a downstream connects. Mobile devices may reconnect pretty
frequently.

Check at most once a day.

database/database.go

@@ -257,6 +257,8 @@ type WebPushConfig struct {
 type WebPushSubscription struct {
 	ID                   int64
 	Endpoint             string
+	CreatedAt, UpdatedAt time.Time // read-only
+
 	Keys struct {
 		Auth   string
 		P256DH string

database/postgres.go

@@ -849,7 +849,7 @@ func (db *PostgresDB) ListWebPushSubscriptions(ctx context.Context, userID, netw
 	}
 
 	rows, err := db.db.QueryContext(ctx, `
-		SELECT id, endpoint, key_auth, key_p256dh, key_vapid
+		SELECT id, endpoint, created_at, updated_at, key_auth, key_p256dh, key_vapid
 		FROM "WebPushSubscription"
 		WHERE "user" = $1 AND network IS NOT DISTINCT FROM $2`, userID, nullNetworkID)
 	if err != nil {
@@ -860,7 +860,7 @@ func (db *PostgresDB) ListWebPushSubscriptions(ctx context.Context, userID, netw
 	var subs []WebPushSubscription
 	for rows.Next() {
 		var sub WebPushSubscription
-		if err := rows.Scan(&sub.ID, &sub.Endpoint, &sub.Keys.Auth, &sub.Keys.P256DH, &sub.Keys.VAPID); err != nil {
+		if err := rows.Scan(&sub.ID, &sub.Endpoint, &sub.CreatedAt, &sub.UpdatedAt, &sub.Keys.Auth, &sub.Keys.P256DH, &sub.Keys.VAPID); err != nil {
 			return nil, err
 		}
 		subs = append(subs, sub)

database/sqlite.go

@@ -1067,7 +1067,7 @@ func (db *SqliteDB) ListWebPushSubscriptions(ctx context.Context, userID, networ
 	}
 
 	rows, err := db.db.QueryContext(ctx, `
-		SELECT id, endpoint, key_auth, key_p256dh, key_vapid
+		SELECT id, endpoint, created_at, updated_at, key_auth, key_p256dh, key_vapid
 		FROM WebPushSubscription
 		WHERE user = ? AND network IS ?`, userID, nullNetworkID)
 	if err != nil {
@@ -1078,9 +1078,12 @@ func (db *SqliteDB) ListWebPushSubscriptions(ctx context.Context, userID, networ
 	var subs []WebPushSubscription
 	for rows.Next() {
 		var sub WebPushSubscription
-		if err := rows.Scan(&sub.ID, &sub.Endpoint, &sub.Keys.Auth, &sub.Keys.P256DH, &sub.Keys.VAPID); err != nil {
+		var createdAt, updatedAt sqliteTime
+		if err := rows.Scan(&sub.ID, &sub.Endpoint, &createdAt, &updatedAt, &sub.Keys.Auth, &sub.Keys.P256DH, &sub.Keys.VAPID); err != nil {
 			return nil, err
 		}
+		sub.CreatedAt = createdAt.Time
+		sub.UpdatedAt = updatedAt.Time
 		subs = append(subs, sub)
 	}
 

downstream.go

@@ -3230,10 +3230,13 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 				}}
 			}
 
+			updateSub := true
 			oldSub := findWebPushSubscription(subs, endpoint)
 			if oldSub != nil {
 				// Update the old subscription instead of creating a new one
 				newSub.ID = oldSub.ID
+				// Rate-limit subscription checks
+				updateSub = time.Since(oldSub.UpdatedAt) > webpushCheckSubscriptionDelay || oldSub.Keys != newSub.Keys
 			}
 
 			var networkID int64
@@ -3242,6 +3245,7 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 			}
 
 			// Send a test Web Push message, to make sure the endpoint is valid
+			if updateSub {
 				err = dc.srv.sendWebPush(ctx, &webpush.Subscription{
 					Endpoint: newSub.Endpoint,
 					Keys: webpush.Keys{
@@ -3269,6 +3273,7 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 						Params:  []string{"WEBPUSH", "INTERNAL_ERROR", subcommand, "Internal error"},
 					}}
 				}
+			}
 
 			dc.SendMessage(&irc.Message{
 				Prefix:  dc.srv.prefix(),

server.go

@@ -39,6 +39,7 @@ var upstreamMessageBurst = 10
 var backlogTimeout = 10 * time.Second
 var handleDownstreamMessageTimeout = 10 * time.Second
 var downstreamRegisterTimeout = 30 * time.Second
+var webpushCheckSubscriptionDelay = 24 * time.Hour
 var chatHistoryLimit = 1000
 var backlogLimit = 4000