Lwm2m blockwise data transfer (using Block1 option) with Leshan not working

[ghseb]

There possibly is bug in sn_coap_protocol.c that breaks Block1 data transfer from Leshan servers to mbed clients.

Description

• Type: Bug
• Priority: Major

---

Bug

mbed-os sha:
8828635

Actual behavior
When transmitting data as block-wise PUT (Coap Block1) from Leshan to a mbed device the token of the acknowledgement (Coap Continue) differs from token of the block-message. Leshan then thinks that the block transfer has failed and no further blocks are sent.

Expected behavior
Coap Continue uses the same token as the Block1 Message it acknowledges.

Suggested solution
Copy the token of the Block1 message into the acknowledgement (Coap Continue).

[0xc0170]

cc @SeppoTakalo

[SeppoTakalo]

CC: @yogpan01 @JanneKiiskila This CoAP library is owned by client teams. Please check this bug.

[JanneKiiskila]

@anttiylitokola - can you check this? IOTCLT-1880 raised internally.

[anttiylitokola]

@JanneKiiskila, Fix is waiting for review.
PelionIoT/mbed-coap#25