Invalid CONNACK packet

[cepr]

The CONNACK packet generated by TinyMqtt doesn't look right.

TinyMqtt generated this: 20 82 00 00 00 I was expecting: 20 02 xx xx (Assuming MQTT 3.1.1)

This bug prevents Adafruit_MQTT_Library from connecting to this broker. I'm sure other MQTT clients will have the same issue.

[xenoeng]

This might explain why I couldn't connect from either MQTT Explorer on the PC or from MQTT Analyser on my phone. I could connect to the AP fine but had no luck with any client. Thought it was something I was missing.

[cepr]

I fixed this issue by replacing:

MqttMessage msg(MqttMessage::Type::ConnAck);
msg.add(0);	// Session present (not implemented)
msg.add(0); // Connection accepted
msg.sendTo(this);

to:

write("\x20\x02\x00\x00", 4);

Unfortunately, I am getting more errors now. I switched to sMQTTBroker which works better for me.

[hsaturn]

Hello cepr

For some optimisation reasons, the size with TinyMQTT is always on 2 bytes. This is the reason for which you have 0x82 00 and not 0x02, this should not be a bug but ....

And.... for an obscure reason, the ConnAck packet does not respect the variable packet length encoding (see 2.2.3 Remaining Length).

As you've pointed this bug, I have to rewrite the packet length encoding...

Thanks for your report.

[hsaturn]

Back...

I wrote a data observer in ESP8266 Wifi mock in order to add a unit test before fixing that bug.

[hsaturn]

Some news : using the new feature of ESP8266 Mock, I can see this :

       |   data sent  15 : Connect     10 8C 00 00 04 4D 51 54 54 04 00 00 0A 00 00 
       |   data sent   5 : ConnAck     20 82 00 00 00 
       |   data sent  11 : Subscribe   82 88 00 00 00 00 03 61 2F 62 00 
       |   data sent   6 : SubAck      90 83 00 00 00 00 
       |   data sent  11 : Subscribe   82 88 00 00 00 00 03 61 2F 62 00 
       |   data sent   3 : Disconnect  E0 80 00 

Thanks to this unit test, the fix will long last :-)

[hsaturn]

Hello cepr

I've fixed the length encoding for (all) messages. It it possible for you to check the latest git version (not released yet) so can release the version ?

       |   data sent  14 : Connect     10 0C 00 04 4D 51 54 54 04 00 00 0A 00 00                   [....MQTT......]
       |   data sent   4 : ConnAck     20 02 00 00                                                 [ ...]
       |   data sent  10 : Subscribe   82 08 00 00 00 03 61 2F 62 00                               [�.....a/b.]
       |   data sent   5 : SubAck      90 03 00 00 00                                              [�....]
       |   data sent  10 : Subscribe   82 08 00 00 00 03 61 2F 62 00                               [�.....a/b.]
       |   data sent   2 : Disconnect  E0 00                                                       [�.]

Thanks again for reporting.

[cepr]

Thanks hsaturn, I'll try now!

[hsaturn]

Thanks hsaturn, I'll try now!

Thanks to you. Keep in mind that this is the git version yet, the lib has not been released with the fix yet.

[cepr]

It works, thanks hsaturn.

Here are the tests I did: rev 7bd299ec07ec6ac8e4d82c8a329707a5158bd610

This broker is now compatible with the following clients:

• NodeRed on Linux (npm module "mqtt", rev 4.3.7, https://www.npmjs.com/package/mqtt)
• Platform.IO library 256dpi/MQTT@^2.5.0) on ESP8266
• Platform.IO library adafruit/Adafruit MQTT@^2.4.3 on ESP8266

The board I am using is not very common and requires a different include for the WiFi to work, I added those lines in TinyMqtt.h for my testing:

#ifdef WIO_TERMINAL
#include <rpcWiFi.h>
#endif

[hsaturn]

Thanks a lot Cedric !!!

I will add the 3 lines you mention. Even if I do not know who else than you will use them, and even if I do not understand what they mean.

I have released the 0.9.0 version with this bugfix. But it seems now that my lib cannot be installed easilly (dependency with AsyncTCP...)

Also I have to fix a bug on incomplete decoding of topics (Issue #30).

Release 0.9.2 includes your lines. The 1.0.0 is not far, thanks to you