qbittorrent: it listens on the port the mesh gave it, rather than fixing it

The manifest published 8112:8112 and 6881:6881 because qBittorrent refuses
a Host naming another port and announces its torrent port to peers — so the
machine port must equal the software's. Fixing the number in the manifest
states a machine port in a definition. Instead the server runs on the host
network and listens where the mesh put it (WEBUI_PORT=${port:8112},
TORRENTING_PORT=${port:6881}): the two are equal by construction on every
machine, and an assignment still pins 8112/6881 where clients know them.

Verified: the pinned image on the host network with WEBUI_PORT=18710 and
TORRENTING_PORT=18711 served the web UI on 18710 (200, no Host mismatch)
and listened for peers on 18711 tcp+udp.

modules/qbittorrent/client.ts

@@ -3,8 +3,10 @@
 // qbittorrent. Both this module's tools and its events entrypoint import it, and nothing outside
 // qbittorrent does.
 //
-// The WebUI authenticates with a session cookie (SID) obtained by POSTing credentials, and guards
-// against CSRF by checking the Referer header. Node's fetch keeps no cookie jar, so the SID is
+// The WebUI authenticates with a session cookie obtained by POSTing credentials, and guards
+// against CSRF by checking the Referer header. The cookie was `SID` before qBittorrent 5.2 and is
+// `QBT_SID_<port>` since, and a successful login answers 200 "Ok." before and 204 with no body
+// since — both are accepted. Node's fetch keeps no cookie jar, so the cookie is
 // captured on login and carried by hand on every later call, with a single re-login on expiry.
 
 import { readFileSync } from "node:fs";
@@ -39,6 +41,21 @@ function meshConfig(file?: string): Record<string, string> {
   catch { return {}; }
 }
 
+/** The WebUI username from qBittorrent's own qBittorrent.conf, in the config directory the mesh
+ *  mounts read-only (MESH_QBITTORRENT_CONFIG_DIR, which is the container's /config). The software's
+ *  file is the truth about who may log in, so the tools ask it rather than a setting that could
+ *  disagree. Absent, unreadable or unset yields undefined. */
+function confUsername(dir: string | undefined): string | undefined {
+  if (!dir) return undefined;
+  try {
+    const line = readFileSync(`${dir.replace(/\/$/, "")}/qBittorrent/qBittorrent.conf`, "utf8")
+      .split(/\r?\n/)
+      .find((l) => l.startsWith("WebUI\\Username="));
+    const value = line?.slice("WebUI\\Username=".length).trim();
+    return value ? value : undefined;
+  } catch { return undefined; }
+}
+
 /** Read a secret the mesh mounted at a file path (an own-secret delivered by `secret accept`);
  *  absent or unreadable yields undefined so callers fall back rather than crash. */
 function readSecret(file?: string): string | undefined {
@@ -49,7 +66,8 @@ function readSecret(file?: string): string | undefined {
 
 export class QbittorrentClient {
   readonly baseUrl: string;
-  private sid: string | null = null;
+  /** The session cookie as `name=value`, sent back exactly as it was set. */
+  private session: string | null = null;
 
   constructor(
     baseUrl: string,
@@ -63,7 +81,9 @@ export class QbittorrentClient {
    * Build from the module's resolved environment. URL and password are read from
    * MESH_QBITTORRENT_URL and MESH_QBITTORRENT_PASSWORD; both must be present — an unconfigured
    * qBittorrent throws rather than pretend to be reachable, so the tools/events simply do not load
-   * (the harness treats the throw as "exposes nothing"). The user defaults to "admin".
+   * (the harness treats the throw as "exposes nothing"). The user is read from qBittorrent.conf,
+   * falling back to "admin", the image's default. The password cannot be read there — qBittorrent
+   * keeps only a PBKDF2 hash — so it is the own-secret the operator accepts.
    */
   static fromEnv(env: NodeJS.ProcessEnv = process.env): QbittorrentClient {
     const cfg = meshConfig(env.MESH_QBITTORRENT_CONFIG_FILE);
@@ -72,7 +92,9 @@ export class QbittorrentClient {
     if (!url || !password) {
       throw new Error("qBittorrent not configured — set MESH_QBITTORRENT_URL and MESH_QBITTORRENT_PASSWORD");
     }
-    const user = cfg.user ?? env.MESH_QBITTORRENT_USER ?? "admin";
+    // The WebUI username: a setting or the environment if one says so, else whatever
+    // qBittorrent.conf holds (an adopted machine keeps its own), else the image's "admin".
+    const user = cfg.user ?? env.MESH_QBITTORRENT_USER ?? confUsername(env.MESH_QBITTORRENT_CONFIG_DIR) ?? "admin";
     return new QbittorrentClient(url, user, password);
   }
 
@@ -82,19 +104,22 @@ export class QbittorrentClient {
       headers: { "Content-Type": "application/x-www-form-urlencoded", Referer: this.baseUrl },
       body: new URLSearchParams({ username: this.user, password: this.password }),
     });
+    if (res.status === 401) throw new Error("qBittorrent login rejected — check credentials");
     if (!res.ok) throw new Error(`qBittorrent login: ${res.status} ${await res.text()}`);
-    if ((await res.text()).trim() !== "Ok.") {
+    // 4.x/5.0/5.1 answer 200 "Ok." or 200 "Fails."; 5.2 answers 204 with no body, or 401.
+    const body = (await res.text()).trim();
+    if (res.status !== 204 && body !== "Ok.") {
       throw new Error("qBittorrent login rejected — check credentials");
     }
-    const match = res.headers.get("set-cookie")?.match(/SID=([^;]+)/);
-    if (!match) throw new Error("qBittorrent login returned no SID cookie");
-    this.sid = match[1];
+    const match = res.headers.get("set-cookie")?.match(/((?:QBT_)?SID(?:_\d+)?)=([^;]+)/);
+    if (!match) throw new Error("qBittorrent login returned no session cookie");
+    this.session = `${match[1]}=${match[2]}`;
   }
 
   private async call(method: "GET" | "POST", path: string, form?: Record<string, string>): Promise<Response> {
-    if (!this.sid) await this.login();
+    if (!this.session) await this.login();
     const doFetch = (): Promise<Response> => {
-      const headers: Record<string, string> = { Referer: this.baseUrl, Cookie: `SID=${this.sid}` };
+      const headers: Record<string, string> = { Referer: this.baseUrl, Cookie: this.session ?? "" };
       const init: RequestInit = { method, headers };
       if (form) {
         headers["Content-Type"] = "application/x-www-form-urlencoded";
@@ -103,8 +128,8 @@ export class QbittorrentClient {
       return fetch(`${this.baseUrl}/api/v2/${path}`, init);
     };
     let res = await doFetch();
-    if (res.status === 403) {
-      // The SID expired — re-authenticate once and retry, rather than fail a routine call.
+    if (res.status === 403 || res.status === 401) {
+      // The session expired — re-authenticate once and retry, rather than fail a routine call.
       await this.login();
       res = await doFetch();
     }

modules/qbittorrent/module.json

@@ -17,10 +17,24 @@
   "listens": [
     {
       "name": "web",
-      "port": 8080,
+      "port": 8112,
       "protocol": "tcp",
       "from": "mesh",
-      "why": "the download client's pages"
+      "why": "the download client's pages, and the WebUI API its consumers and its own tools call. qBittorrent refuses a request whose Host names a port other than the one it listens on, so it listens on the machine port itself (host network, WEBUI_PORT=${port:8112}) and the two cannot differ on any machine"
+    },
+    {
+      "name": "peers",
+      "port": 6881,
+      "protocol": "tcp",
+      "from": "mesh",
+      "why": "incoming BitTorrent peer connections; announced to trackers and peers, so qBittorrent listens on the machine port itself (TORRENTING_PORT=${port:6881})"
+    },
+    {
+      "name": "peers-udp",
+      "port": 6881,
+      "protocol": "udp",
+      "from": "mesh",
+      "why": "DHT and uTP on the same number as the peer port"
     }
   ],
   "accesses": [
@@ -36,10 +50,15 @@
       "path": "/var/lib/mesh/qbittorrent",
       "mode": "0700"
     },
+    {
+      "id": "state",
+      "type": "directory",
+      "mode": "0700",
+      "place": "."
+    },
     {
       "id": "config",
       "type": "directory",
-      "path": "/services/qbittorrent/config",
       "mode": "0700",
       "owner": "1000:1000"
     },
@@ -47,24 +66,24 @@
       "id": "server",
       "type": "container",
       "name": "qbittorrent",
-      "image": "lscr.io/linuxserver/qbittorrent@sha256:a00b6a597a3832a1814cde0ef60abc55c94644f3f80902c3432f6af6de8d4a96",
+      "image": "lscr.io/linuxserver/qbittorrent@sha256:457e4eec2ee3f5e4ef59f237ad51f6143deba9f7445ab48bb5204a98888ef9aa",
       "env": {
         "PUID": "1000",
         "PGID": "1000",
-        "TZ": "Etc/UTC"
+        "TZ": "Etc/UTC",
+        "WEBUI_PORT": "${port:8112}",
+        "TORRENTING_PORT": "${port:6881}"
       },
-      "ports": [
-        "8080"
-      ],
       "volumes": [
-        "/services/qbittorrent/config:/config",
+        "${dir:config}:/config",
         "/services/media/downloads:/downloads"
-      ]
+      ],
+      "network": "host"
     },
     {
       "id": "runtime-config",
       "type": "file",
-      "path": "/var/lib/mesh/qbittorrent/config.json",
+      "path": "${dir:state}/config.json",
       "mode": "0600",
       "content": "{}\n",
       "merge": "json"
@@ -77,22 +96,46 @@
       "volumes": [
         "/var/lib/mesh/qbittorrent/broker:/run/secrets/broker:ro",
         "/var/lib/mesh/qbittorrent/password:/run/secrets/password:ro",
-        "/var/lib/mesh/qbittorrent/config.json:/run/config/config.json:ro",
-        "/services/qbittorrent/config:/var/lib/qbittorrent/config:ro"
+        "${dir:state}/config.json:/run/config/config.json:ro",
+        "${dir:config}:/var/lib/qbittorrent/config:ro"
       ],
       "env": {
         "MESH_BROKER_FILE": "/run/secrets/broker",
-        "MESH_QBITTORRENT_URL": "http://127.0.0.1:8080",
+        "MESH_QBITTORRENT_URL": "http://127.0.0.1:${port:8112}",
         "MESH_QBITTORRENT_PASSWORD_FILE": "/run/secrets/password",
         "MESH_QBITTORRENT_CONFIG_FILE": "/run/config/config.json",
         "MESH_QBITTORRENT_CONFIG_DIR": "/var/lib/qbittorrent/config"
       },
       "restart-on": [
-        "runtime-config"
+        "runtime-config",
+        "needs-password"
       ],
       "artifact": "runtime"
     }
   ],
+  "provides": [
+    "qbittorrent-api"
+  ],
+  "serves": {
+    "qbittorrent-api": {
+      "scheme": "http",
+      "port": 8112,
+      "url-base": "",
+      "username": "admin"
+    }
+  },
+  "requires": [
+    "route"
+  ],
+  "contributes": {
+    "route": {
+      "label": "qbittorrent",
+      "endpoint": "web"
+    }
+  },
+  "binds": {
+    "route": "${dir:state}/route.json"
+  },
   "build": {
     "on": [
       {