Sending D2C messages still continue after SAS token expires for MQTT protocol

[luyaok]

• SDK version used: Microsoft.Azure.Devices.Client 1.17.0

Description of the issue:

Sending D2C messages still continue successfully after SAS token expires for MQTT protocol. But for AMQP, about 10 minutes after the token expires you will get UnauthorizedException. For HTTP, this time is about 5 minutes.

Code sample exhibiting the issue:

DeviceClient.Create(hostname, new DeviceAuthenticationWithToken("device1", devicetoken), TransportType.Mqtt);

Controlling access using MQTT not working, this is expected behavior? And why there is a difference in the time between AMQP and HTTP, 5 minutes and 10 minutes?

[CIPop]

Thank you @luyaok for reporting this! This is known and, last I've checked, the fix was already deployed.
Please let us know if you can still repro this issue.

[amogh79]

@CIPop Our device team is using C SDK and I need to let them know if the fix was rolled out. I have already commented here [https://github.com/Azure/azure-iot-sdk-c/issues/163] to know when the fix would be rolled out for C SDK but I have not got any reply yet. Also was the fix that was deployed was for the SDK or the IoT Hub? If it was for IoT Hub then this issue should be fixed across all sdks...right??

[CIPop]

@amogh79 the SAS expiry time is controlled by the service (where the fix was gradually rolled out). If you find that your subscription is still experiencing these issues, please open a support ticket for us to investigate.

A time allowance of about 5 minutes is added to the expiry time of the SAS token to account for eventual clock drift. If the SDK is used with a SharedKey, the SDK should be able to automatically generate valid SAS tokens so that the connection is kept alive (this is transparent for the application).

And why there is a difference in the time between AMQP and HTTP, 5 minutes and 10 minutes?

@luyaok - I don't think there should be a difference: have you checked the clock drift on devices using AMQP vs ones using HTTP?