fix: keep sequence counter in sync with device-initiated packets

index.js

@@ -739,6 +739,18 @@ class TuyaDevice extends EventEmitter {
   }
 
   _packetHandler(packet) {
+    // Keep our outgoing sequence counter in sync with the device's.
+    // The device advances its own sequence number for every packet it sends,
+    // including unsolicited ones (e.g. the STATUS/DP_REFRESH push it emits right
+    // after a SET). If we don't account for those, our next request reuses a
+    // sequence number the device has already consumed, so its reply no longer
+    // matches the resolver we registered and the pending get()/set() hangs until
+    // the socket is recycled. Re-syncing here makes request/resolver matching
+    // survive device-initiated packets.
+    if (packet.sequenceN > this._currentSequenceN) {
+      this._currentSequenceN = packet.sequenceN;
+    }
+
     // Protocol 3.4, 3.5 - Response to Msg 0x03
     if (packet.commandByte === CommandType.SESS_KEY_NEG_RES) {
       if (!this.connectPromise) {

test/sequence.js

@@ -0,0 +1,64 @@
+import test from 'ava';
+
+const TuyAPI = require('..');
+
+// A Tuya device advances its own sequence number for every packet it sends,
+// including unsolicited ones (e.g. the STATUS/DP_REFRESH push emitted right
+// after a SET). TuyAPI must re-sync its outgoing counter from received packets:
+// otherwise the next request reuses a sequence number the device has already
+// consumed, the device answers with a different number, and the resolver we
+// registered is never called — so the pending get()/set() hangs until the socket
+// is recycled.
+
+function makeDevice() {
+  const device = new TuyAPI({id: '22325186db4a2217dc8e',
+                             key: '4226aa407d5c1e2b',
+                             ip: '127.0.0.1',
+                             version: '3.4'});
+  // Pretend a session is already established and swallow socket writes.
+  device._connected = true;
+  device.client = {write() {}};
+  return device;
+}
+
+test('re-syncs the sequence counter from an unsolicited device packet', t => {
+  const device = makeDevice();
+  device._currentSequenceN = 98;
+
+  // The device pushes a STATUS packet using sequence 100; our counter is behind.
+  device._packetHandler({commandByte: 8, sequenceN: 100, payload: {dps: {3: 15}}});
+
+  t.is(device._currentSequenceN, 100);
+});
+
+test('does not rewind the sequence counter on an older packet', t => {
+  const device = makeDevice();
+  device._currentSequenceN = 100;
+
+  device._packetHandler({commandByte: 8, sequenceN: 90, payload: {dps: {3: 15}}});
+
+  t.is(device._currentSequenceN, 100);
+});
+
+test('a pending request still resolves after an unsolicited push', t => {
+  const device = makeDevice();
+  let deviceSequenceN = 200; // the last sequence number the device has used
+
+  // The device pushes an unsolicited packet, advancing its own counter.
+  deviceSequenceN++;
+  device._packetHandler({commandByte: 8, sequenceN: deviceSequenceN, payload: {dps: {3: 15}}});
+
+  // Issue a read the way get()/_send() do: claim the next sequence number and
+  // register a resolver for it.
+  const requestSequenceN = ++device._currentSequenceN;
+  let received;
+  device._resolvers[requestSequenceN] = payload => {
+    received = payload;
+  };
+
+  // The device answers on the sequence number that follows the one it last used.
+  deviceSequenceN++;
+  device._packetHandler({commandByte: 16, sequenceN: deviceSequenceN, payload: {dps: {1: true}}});
+
+  t.is(received.dps['1'], true);
+});