The existing LwM2M framework expected contiguous buffers and this
was the reason for the 384 byte buffer sizes. This was previously
a limitation of the ZoAP API. The new CoAP API doesn't have this
limitation and the LwM2M library has already been migrated to use
it.
Let's finish the process by replacing any contiguous buffer handling
with the correct net_pkt APIs to parse across multiple fragments.
Signed-off-by: Michael Scott <michael.scott@linaro.org>
Origin: SICS-IoT / Contiki OS
URL: https://github.com/sics-iot/lwm2m-contiki/tree/lwm2m-standalone-dtls
commit: d07b0bcd77ec7e8b93787669507f3d86cfbea64a
Purpose: Introduction of LwM2M client library.
Maintained-by: Zephyr
Lightweight Machine-to-Machine (LwM2M) is a protocol stack extension
of the Constrained Application Protocol (CoAP) which uses UDP
transmission packets.
This library was based on source worked on by Joakim Eriksson,
Niclas Finne and Joel Hoglund which was adopted by Contiki and then
later revamped to work as a stand-alone library.
A VERY high level summary of the changes made:
- [ALL] sources were re-formatted to Zephyr coding standards
- [engine] The engine portion was re-written due to the heavy reliance
on ER-CoAP APIs which are not compatible to the Zephyr CoAP APIs as
well as other Zephyr specific needs.
- [engine] All LWM2M/IPSO object data is now abstracted into resource
data which stores information like the data type, length, callbacks
to help with read/write. The engine modifies this data directly (or
makes callbacks) instead of all of the logic for this living in each
object's code. (This wasn't scaling well as I was implementing
changes).
- [engine] Related to the above change, I also added a generic set of
getter/setter functions that user applications can call to change
the object data instead of having to add getter/setting methods in
each object.
- [engine] The original sources shared the engine's context structure
quite extensively causing a problem with portability. I broke up the
context into it's individual parts: LWM2M path data, input data and
output data and pass only the needed data into each set of APIs.
- [content format read/writer] sources were re-organized into single
.c/h files per content formatter.
- [content format read/writer] sources were re-written where necessary
to remove the sharing of the lwm2m engine's context and instead only
requires the path and input or output data specific to it's
function.
- [LwM2M objects] re-written using the new engine's abstractions
Signed-off-by: Michael Scott <michael.scott@linaro.org>
Michael Scott