Crash in isTopicMatched

[iheb-eddine]

Hello,

I am using the AWS Iot project into an embedded C project.
Sometime when I update shadow, I got a crash on the function isTopicMatched.
When I debug the crash, I found the error on topicName parameter:

(gdb) p topicName.lenstring
$41 = {len = 8820, data = 0x0}

Am I doing something wrong or it is a bug?

Many thanks,
Iheb Eddine

[johnrotach]

Hello Iheb,

Can you provide a little more context around what you are doing? How large of a shadow update response are you expecting? You say it happens sometimes - can you give more information around when it fails?

John
AWS IoT

[iheb-eddine]

Hello,

Thank you for your reply.
I am using a shadow with attributes, 2 integers and one string little than 25 chars.
Yesterday I fixed the problem by changing the values of AWS_IOT_MQTT_TX_BUF_LEN and AWS_IOT_MQTT_RX_BUF_LEN.
But with this changes, we don't solve the problem, because when we will have a big data we will have a crash again.

I debugged your source and I found the reason of the error.
It is on the function MQTTDeserialize_publish, on the file aws_mqtt_embedded_client_lib/MQTTPacket/src/MQTTDeserializePublish.c
We just need to change from:
if (!readMQTTLenString(topicName, &curdata, enddata) ||
enddata - curdata < 0) /* do we have enough data to read the protocol version byte? */
goto exit;

TO:
if (!readMQTTLenString(topicName, &curdata, enddata) ||
enddata - curdata < 0) /* do we have enough data to read the protocol version byte? */
{
rc = 0;
goto exit;
}

I still find many issues on parsing JSON by the library and disconnecting problems, shall I make an issue for each problem or can I send an email about that?

Thank you,
Iheb Eddine

[johnrotach]

Hi Iheb,

Thanks a lot for pointing out this issue and providing a fix! This bug has already been fixed in an internal branch of the MQTT client (along with other small fixes) and will make it in our next release (1.1.0). I anticipate this release to happen next week.

Please submit issues for any problems you may find. It is always appreciated!

John

[revmischa]

I had this exact same issue. Upgrading to the latest client version (and doing a clean) fixed the issue for me, it reports -28 now if the recv buffer is too small.

[chaurah]

Hi @iheb-eddine,
We have also made several changes in the new v2.x release of the SDK to address this and various other issues that have been reported so far. Please download the new version and let us know if the issues you were facing are still there. Any suggestions you might have for improvement are always appreciated.

@revmischa Thank you for confirming that the issue is fixed in the 1.x branch as well.

Rahul

[iheb-eddine]

Hi @chaurah,
The issue is fixed on the last version.
Thank you for your support.

Regards,
Iheb Eddine