mqttClient error: invalid operation. Wemos D1 Mini

[colinl]

I have a trivial flow consisting just of an mqtt In node feeding a debug node, running on a Wemos D1 Mini.
For some particular combinations of topic and data then every time I publish the data to that topic, in xsbug I see
mqttClient error: invalid operation
and in the mosquitto log I see the client disconnect and reconnect again

2023-04-11 10:04:49: Client node-red-75fb29423f8a0770-1681203830270-6933 closed its connection.
2023-04-11 10:04:50: New connection from 192.168.1.245:22564 on port 1883.
2023-04-11 10:04:50: New client connected from 192.168.1.245:22564 as node-red-75fb29423f8a0770-1681203830270-6933 (p2, c1, k60000).

If I change the topic or the data then it works fine, which is very odd. So far this is the only combination of topic and data that I have found that fails:
topic: "tydwr/mcu/config"
and data

{
    "analogue_0": {
        "period": 100,
        "topic": "tydwr/charger/adc_mcu"
    },
    "DS18B20": {
        "globalPeriod": 10000,
        "sensors": {
            "28ff0c36511604df": "tydwr/ds18b20/hw_cyl_2",
            "282856ac0300005f": "tydwr/ds18b20/sensor1",
            "28ff550656160308": "tydwr/ds18b20/sensor2"
        }
    }
}

This is the flow in the D1 Mini

[{"id":"ab2bacdb9ebd5d92","type":"mqtt in","z":"17edb54d5e9276ec","name":"","topic":"tydwr/mcu/config","qos":"1","datatype":"json","broker":"75fb29423f8a0770","nl":false,"rap":true,"rh":0,"inputs":0,"x":200,"y":140,"wires":[["6442fc7aa866b0d9"]]},{"id":"6442fc7aa866b0d9","type":"debug","z":"17edb54d5e9276ec","name":"debug 90","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":420,"y":140,"wires":[]},{"id":"75fb29423f8a0770","type":"mqtt-broker","name":"Owl2 for mcu","broker":"192.168.1.83","port":"1883","clientid":"","autoConnect":true,"usetls":false,"protocolVersion":"4","keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","birthMsg":{},"closeTopic":"","closeQos":"0","closePayload":"","closeMsg":{},"willTopic":"","willQos":"0","willPayload":"","willMsg":{},"userProps":"","sessionExpiry":""}]

This is the Inject node used to publish the data from the machine running the broker

[{"id":"6e26c91d7ad41ff8","type":"inject","z":"77ec6bf6.962f64","name":"mqtt test","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":"10","topic":"tydwr/mcu/config","payload":"{\"analogue_0\":{\"period\":100,\"topic\":\"tydwr/charger/adc_mcu\"},\"DS18B20\":{\"globalPeriod\":10000,\"sensors\":{\"28ff0c36511604df\":\"tydwr/ds18b20/hw_cyl_2\",\"282856ac0300005f\":\"tydwr/ds18b20/sensor1\",\"28ff550656160308\":\"tydwr/ds18b20/sensor2\"}}}","payloadType":"json","x":140,"y":1420,"wires":[["fd9655766a56ec3e"]]}]

I am running the latest node-red-mcu pulled from github. I am not using the node red plugin for this test.

[colinl]

I suspect this is a buffer overflow or uninitialised variable or something similar. Trivial changes to the data can make it fail or run successfully.

[phoddie]

Thanks for the report. I'll try to reproduce this on my set-up. The error being reported, invalid operation, appears to be coming from the MQTT parser of received data. It indicates that the first byte of a message from the broker is an invalid MQTT opcode (either 0 or 15).

[phoddie]

I wasn't able to reproduce the same error. Here's what I tried:

• Use test.mosquitto.org as the broker
• Run the mqtt out node in Node-RED (computer) with a repeat interval of 0.05 seconds (20 messages per second)
• Run the mqtt in node on ESP8266

That would work for a bit and then eventually fail with a "fragmented receive unimplemented" exception. That is a reminder to me to implement fragmented MQTT receive. So I did. That's committed. Now the flow runs solidly for me on ESP8266 (several minutes, no exceptions, messages continuously received).

I don't think this is the same error you saw, as it would have cause the ESP8266 to reboot instead of reporting "mqttClient error: invalid operation.

I think you are running a different MQTT Broker, probably something local. Should I try to match that? Other ideas for how I might be able to reproduce this?

[colinl]

No, that isn't the same problem. For me the flow fails immediately on the first message received. I am using mosquitto locally. I will see if I can make it fail with the public test broker.

[colinl]

Ok, I have it failing with test.mosquitto.org.
I pulled the latest versions of node-red-mcu and Moddable, and rebuild the moddable tools.
I have this flow in node-red

[{"id":"b1d22625332df051","type":"mqtt in","z":"17edb54d5e9276ec","name":"","topic":"tydwr/mcu/config","qos":"1","datatype":"json","broker":"450307207f1c7206","nl":false,"rap":true,"rh":0,"inputs":0,"x":120,"y":120,"wires":[["8e4a85438c2e6f14"]]},{"id":"8e4a85438c2e6f14","type":"debug","z":"17edb54d5e9276ec","name":"debug 87","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":280,"y":120,"wires":[]},{"id":"450307207f1c7206","type":"mqtt-broker","name":"test.mosquitto.org","broker":"test.mosquitto.org","port":"1883","clientid":"","autoConnect":true,"usetls":false,"protocolVersion":"4","keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","birthMsg":{},"closeTopic":"","closeQos":"0","closePayload":"","closeMsg":{},"willTopic":"","willQos":"0","willPayload":"","willMsg":{},"userProps":"","sessionExpiry":""}]

I build and run it on a Wemos D1 Mini using
mcconfig -d -m -p esp/nodemcu ssid=...
Then in my local machine I run

[{"id":"775b661a50458a75","type":"inject","z":"77ec6bf6.962f64","name":"mcu config","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":"10","topic":"tydwr/mcu/config","payload":"{\"analogue_0\":{\"period\":100,\"topic\":\"tydwr/charger/adc_mcu\"},\"DS18B20\":{\"globalPeriod\":10000,\"sensors\":{\"28ff0c36511604df\":\"tydwr/ds18b20/hw_cyl_2\",\"282856ac0300005f\":\"tydwr/ds18b20/sensor1\",\"28ff550656160308\":\"tydwr/ds18b20/sensor2\"}}}","payloadType":"json","x":140,"y":1540,"wires":[["b9f4ae1e058e93c8"]]},{"id":"b9f4ae1e058e93c8","type":"mqtt out","z":"77ec6bf6.962f64","name":"test.mosquitto.org","topic":"","qos":"1","retain":"false","respTopic":"","contentType":"","userProps":"","correl":"","expiry":"","broker":"f4ab502aee074e99","x":410,"y":1540,"wires":[]},{"id":"028062fe6b495324","type":"mqtt in","z":"77ec6bf6.962f64","name":"tydwr/mcu/config","topic":"tydwr/mcu/config","qos":"1","datatype":"auto","broker":"f4ab502aee074e99","nl":false,"rap":false,"inputs":0,"x":160,"y":1600,"wires":[["ff139ea65bddeba1"]]},{"id":"ff139ea65bddeba1","type":"debug","z":"77ec6bf6.962f64","name":"debug 19","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":400,"y":1600,"wires":[]},{"id":"f4ab502aee074e99","type":"mqtt-broker","name":"test.mosquitto.org","broker":"test.mosquitto.org","port":"1883","clientid":"","autoConnect":true,"usetls":false,"protocolVersion":"4","keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","birthMsg":{},"closeTopic":"","closeQos":"0","closePayload":"","closeMsg":{},"willTopic":"","willQos":"0","willPayload":"","willMsg":{},"userProps":"","sessionExpiry":""}]

and as soon as I click the Inject node, xsbug shows mqttClient error: invalid operation.

[phoddie]

@colinl – with your updated instructions, I can reliably reproduce the problem! It happens in the simulator as well as the ESP8266, so it isn't an MCU induced issue. I'll try to fix this later today.

[phoddie]

There was a bug in the parser in the short-circuit for 0 length payloads. Your test payload has a length of 256 bytes and the length of 0 in the first byte erroneously triggered the short-circuit. The mistake is here. The fix will be live tomorrow. If you want to verify it before then, here's the updated version:

				// remaining length
				case 1:
					byte = socket.read();
					parse.length = byte & 0x7F;
					if (byte & 0x80)
						parse.state = 2
					else {
						parse.state = parse.operation << 4;
						if (!parse.length) {		// no payload - handle immediately (PINGREQ, PINGRESP, DISCONNECT)
							if (this.#parsed(parse))
								return;
							parse = {state: 0};
						} 
					}
					break;

I've confirmed this works on both the simulator and ESP8266.

Thanks again for taking the time to isolate this to a simple test case. That made fixing this very straightforward.

[colinl]

Your test payload has a length of 256 bytes

I seem to have a knack of hitting issues like that.

[colinl]

Excellent, I applied the patch and it is working well.

[phoddie]

Woohoo!

[colinl]

Have you had a chance to commit this? I am not seeing it yet.

[phoddie]

Thanks for the reminder. Friday got busy. We posted the update earlier today.

[colinl]

Latest source from repo tested.
Closing this as fixed.

[phoddie]

Excellent, thank you.