Accept 16-character subscription secrets for gateway presence

src/server/gatewayPresence.js

@@ -27,7 +27,7 @@ function subscriptionSecret(subscriptionUrl) {
       pathSegments.at(-1),
     ]
       .map((value) => String(value || '').trim())
-      .filter((value) => value.length >= 24);
+      .filter((value) => value.length >= 16);
     if (!candidates.length) return '';
 
     url.hash = '';

test/server/gateway-presence.test.js

@@ -52,6 +52,13 @@ test('Gateway presence is authenticated by the shared subscription secret', asyn
     nonce,
   }).available, false);
 
+  assert.equal(buildGatewayPresence({
+    appMode: 'gateway',
+    subscriptionUrl: 'https://subscription.example/0123456789abcdef',
+    gatewayId: 'gateway-1',
+    nonce,
+  }).available, true);
+
   const sharedPublicValue = 'https://public.example/sing-box-configuration-v1';
   const firstUrl = `${subscriptionUrl}?redirect=${encodeURIComponent(sharedPublicValue)}`;
   const secondUrl = `https://subscription.example/fedcba9876543210fedcba9876543210?redirect=${encodeURIComponent(sharedPublicValue)}`;