v3: the API stops trusting what it's handed — a review of api/ turned up a server anyone could crash, uploads that ran script on the app's origin, and a server that would fetch its own network on request, and this closes them along with the smaller holes around them. A WebSocket message that wasn't an object (a bare null will do) threw inside the listener, which Deno treats as uncaught and exits on; messages are now shape-checked and the handler can't throw out. Uploaded files kept the MIME type the uploader's browser claimed, so an .html or .svg dump opened from /api/files ran with the session token in reach; only images, audio, video, PDF and plain text are served inline now, the rest download, and every file carries nosniff and a sandboxing CSP (PDFs aside, which Chrome won't render sandboxed). The image proxy passed image/svg+xml straight through the same way and now takes raster formats only. Outbound fetches for previews, the proxy and Bandcamp checked the hostname against a partial list — no 169.254.169.254, no 0.0.0.0, an IPv6 check that never matched a bracketed hostname, nothing for names that resolve inward, and redirects followed blindly; every hop now resolves and is refused if any address is private or reserved, redirects are walked by hand, the curl fallback is pinned to the checked IP, and /api/preview needs a login. PATCH /users/me accepted a new password without the current one and now takes only the description and email; a wrong password at login answered 500 because the handler caught its own 401, and now says 401. Changing or resetting a password now ends every older session through users.tokens_valid_after (migration 0015) and an iat on every token, with change-password handing back fresh tokens the modal keeps, and all token checks go through one authenticate() that also refuses deleted users. Invites and reset links are claimed atomically before the async hash rather than marked after, so one invite no longer opens several accounts, and an email address belongs to one account. File and thumbnail URLs carry a media-only token rather than the session token, so a URL in a log exposes files and not the account; older sessions fetch one on load. Private things stop leaking into broadcasts: private playlist updates go to their owner, votes and likes on someone else's private dump 404 and their counts go to the owner alone, and a private dump can't be slipped into a playlist. Smaller: selfProvider only claims this site's own host, so github.com/users/bob stops rendering our bob; the chat read marker can't be parked in the future on an empty chat; dump mutations use the resolved id so a slug works; multipart dumps get the title and comment limits; logins and reset requests are rate-limited through a shared token bucket; the password compare is constant-time; ffmpeg reads only local files in known video containers.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/services/ws-service.ts

@@ -83,6 +83,18 @@ export function disconnectUser(userId: string): void {
   }
 }
 
+/**
+ * Drops the user's sockets without logging anyone out: each reconnects with
+ * whatever token it holds, and /ws turns a revoked one into a force_logout.
+ * Used on a password change, where the tab that made the change has already
+ * swapped in a fresh token and must stay signed in.
+ */
+export function closeUserSockets(userId: string, reason: string): void {
+  for (const client of clients) {
+    if (client.userId === userId) client.socket.close(1000, reason);
+  }
+}
+
 export function broadcastPresence(): void {
   const users = getOnlineUsers();
   for (const client of clients) {
@@ -108,13 +120,16 @@ export function broadcastDumpDeleted(dumpId: string): void {
   }
 }
 
+// `onlyUserId`: a private dump's count goes to that user's sockets alone.
 export function broadcastVoteUpdate(
   dumpId: string,
   voteCount: number,
   voterId: string,
   action: "cast" | "remove",
+  onlyUserId?: string,
 ): void {
   for (const client of clients) {
+    if (onlyUserId && client.userId !== onlyUserId) continue;
     send(client.socket, {
       type: "votes_update",
       dumpId,
@@ -125,13 +140,16 @@ export function broadcastVoteUpdate(
   }
 }
 
+// `onlyUserId`: a like on a private dump's comment goes to that user alone.
 export function broadcastCommentLikeUpdate(
   commentId: string,
   likeCount: number,
   likerId: string,
   action: "cast" | "remove",
+  onlyUserId?: string,
 ): void {
   for (const client of clients) {
+    if (onlyUserId && client.userId !== onlyUserId) continue;
     send(client.socket, {
       type: "comment_likes_update",
       commentId,
@@ -157,12 +175,17 @@ export function broadcastPlaylistCreated(playlist: Playlist): void {
   sendToPlaylistAudience(playlist, { type: "playlist_created", playlist });
 }
 
-export function broadcastPlaylistUpdated(playlist: Playlist): void {
-  // Broadcast to ALL clients so non-owners can react to visibility changes
-  // (e.g. remove a now-private playlist from their feed).
-  for (const client of clients) {
-    send(client.socket, { type: "playlist_updated", playlist });
-  }
+// `wasPublic`: the visibility before this change. A playlist that just went
+// private still goes to everyone, so non-owners can drop it from their views;
+// one that was and stays private goes to its owner alone.
+export function broadcastPlaylistUpdated(
+  playlist: Playlist,
+  wasPublic: boolean,
+): void {
+  sendToPlaylistAudience(
+    { isPublic: playlist.isPublic || wasPublic, userId: playlist.userId },
+    { type: "playlist_updated", playlist },
+  );
 }
 
 export function broadcastPlaylistDeleted(
@@ -305,44 +328,7 @@ export function isUserChatOpen(userId: string): boolean {
   return false;
 }
 
-// Token buckets keyed by `${kind}:${userId}` — per user rather than per socket,
-// so opening more tabs doesn't buy more throughput.
-interface Bucket {
-  tokens: number;
-  at: number;
-}
-const buckets = new Map<string, Bucket>();
-
-export interface RateLimit {
-  /** Burst size. */
-  capacity: number;
-  /** Tokens regained per second. */
-  refill: number;
-}
-
-/** Takes one token for `key`; false when the bucket is empty. */
-export function takeToken(key: string, limit: RateLimit): boolean {
-  const now = Date.now();
-  const bucket = buckets.get(key) ?? { tokens: limit.capacity, at: now };
-  bucket.tokens = Math.min(
-    limit.capacity,
-    bucket.tokens + ((now - bucket.at) / 1000) * limit.refill,
-  );
-  bucket.at = now;
-  buckets.set(key, bucket);
-  if (bucket.tokens < 1) return false;
-  bucket.tokens -= 1;
-  return true;
-}
-
-// Full buckets carry no information; drop them so the map tracks only users
-// who've been active lately.
-setInterval(() => {
-  const cutoff = Date.now() - 5 * 60_000;
-  for (const [key, bucket] of buckets) {
-    if (bucket.at < cutoff) buckets.delete(key);
-  }
-}, 60_000);
+export { type RateLimit, takeToken } from "../lib/rate-limit.ts";
 
 export function handleClientPong(client: WsClient): void {
   client.pongReceived = true;