Error in AzureIoTHubClient_ProcessLoop

[amolchor20]

Please provide us with the following information:

This issue is for a: (mark with an x)

- [X] bug report -> please search issues before submitting
- [ ] feature request
- [] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

Integrate the mbedTLS library in azure middleware to use TLS_send and TLS_recv.
execute the code and connect to IoT hub, wait for AzureIoTHubClient_ProcessLoop function to execute.

Any log messages given by the failure

[2024-01-05_15:29:42:471][ERROR] [TlsTransport] [transport_tls_socket_using_mbedtls.c:904] Failed to read data: mbedTLSError[-8]= : BIGNUM - The buffer is too small to write to.
[2024-01-05_15:29:42:471][ERROR] [MQTT] [core_mqtt_serializer.c:2394] A single byte was not read from the transport: transportStatus=-8.
[2024-01-05_15:29:42:493][ERROR] [MQTT] [core_mqtt.c:1319] Receiving incoming packet length failed. Status=MQTTRecvFailed
[2024-01-05_15:29:42:493][ERROR] [MQTT] [core_mqtt.c:2191] Exiting process loop due to failure: ErrorStatus=MQTTRecvFailed

Expected/desired behavior

It should be process the received data and complete the workflow of data receive from cloud/sender.

OS and Version?

Windows 7, 8 or 10. Linux (which distribution). macOS (Yosemite? El Capitan? Sierra?)
I am working on stm32u585 board and integrated azure middleware.
to work with TLS_send and TLS_recv I have integrated the mbedTLS 3.4.0 in it.

Versions

mbedTLS 3.4.0

Mention any other details that might be useful

---

Thanks! We'll be in touch soon.

[ericwol-msft]

This error is coming from the BIGNUM lib in the mbed TLS stack, which is an external component to this repo.

This might be relevant.
https://forums.mbed.com/t/bignum-the-buffer-is-too-small-to-write-to/11693

[amolchor25]

@ericwol-msft
Thanks for your reply !!
here are the detailed logs:
basically the processloop error is caused by timeout.

[2024-02-19_11:08:15:556]ip4_output_if: call netif->output()
[2024-02-19_11:08:15:582]pbuf_alloc(length=0)
[2024-02-19_11:08:15:582]pbuf_alloc(length=0) == 0x2000e75c
[2024-02-19_11:08:15:582]lwip_recv_tcp: netconn_recv err=-3, 073581.lwip_recv_tcp: p == NULL, error is "Timeout."!
[2024-02-19_11:08:15:582]lwip_recvfrom(0): addr=23.98.104.211 port=8883 len=-1
[2024-02-19_11:08:15:582]in_left: zu, nb_want: zu

[2024-02-19_11:08:15:632][ERROR] [TlsTransport] [transport_tls_socket_using_mbedtls.c:906] Failed to read data: mbedTLSError[-1]= : ERROR - Generic error.

[2024-02-19_11:09:02:097]pbuf_alloc(length=1)
[2024-02-19_11:09:02:097]pbuf_alloc(length=1) == 0x2000e54c
[2024-02-19_11:09:02:097]tcpip_inpkt: PACKET 0x2000e54c/0x20007498
[2024-02-19_11:09:02:097]pbuf_free(0x2000e54c)
[2024-02-19_11:09:02:097]pbuf_free: deallocating 0x2000e54c
[2024-02-19_11:09:02:838][ERROR] [MQTT] [core_mqtt_serializer.c:2394] A single byte was not read from the transport: transportStatus=-1.

[2024-02-19_11:09:16:383]pbuf_alloc(length=1)
[2024-02-19_11:09:16:383]pbuf_alloc(length=1) == 0x2000e54c
[2024-02-19_11:09:16:383]tcpip_inpkt: PACKET 0x2000e54c/0x20007498
[2024-02-19_11:09:16:383]pbuf_free(0x2000e54c)
[2024-02-19_11:09:16:383]pbuf_free: deallocating 0x2000e54c
[2024-02-19_11:09:33:264]pbuf_alloc(length=1)
[2024-02-19_11:09:33:264]pbuf_alloc(length=1) == 0x2000e54c
[2024-02-19_11:09:33:264]tcpip_inpkt: PACKET 0x2000e54c/0x20007498
[2024-02-19_11:09:33:264]pbuf_free(0x2000e54c)
[2024-02-19_11:09:33:264]pbuf_free: deallocating 0x2000e54c
[2024-02-19_11:09:34:541][ERROR] [MQTT] [core_mqtt.c:1319] Receiving incoming packet length failed. Status=MQTTRecvFailed

[2024-02-19_11:09:49:731][ERROR] [MQTT] [core_mqtt.c:2191] Exiting process loop due to failure: ErrorStatus=MQTTRecvFailed

[2024-02-19_11:10:19:922]pbuf_alloc(length=1)
[2024-02-19_11:10:19:922]pbuf_alloc(length=1) == 0x2000e54c
[2024-02-19_11:10:19:922]tcpip_inpkt: PACKET 0x2000e54c/0x20007498
[2024-02-19_11:10:19:922]pbuf_free(0x2000e54c)
[2024-02-19_11:10:19:922]pbuf_free: deallocating 0x2000e54c
[2024-02-19_11:10:20:239]Wait for properties sub ack failed: error=0x00000001

if there is no data from cloud to device, then how the azure middleware will handle the processloop timeout error?