This allows forwarding GRR-UNITDATA.ind/req up & down the stack, to be
on pair with the BSSGP LLC SAP.
Change-Id: I6a4454b4aa2c96e1f4ce7e2a5d5aba8ec1cf3f60
Most of the existing (and added) data structures are kept private, since
most of those don't really need to be used outside internal code in the
library.
Most if not all the interaction from upper and lower layers towards LLC
is now done through the new llc_prim pubic interface. This interface is
based on 3GPP TS 44.064 section 7.1.2.
This commit also implements some of the code paths of the public API by
means on importing LLC code from osmo-sgsn.git commit
57b63875c762a784127a13becd1c2549ca6c5454.
The import of code cannot be done in a separate commit since existing code
in osmo-sgsn.git is low quality and has tons of layer violations in all
directions.
Hence, this commit aims at being an initial point of having some working
LLC stack by means of a few unit tests, but by no means aims to be a
total working implementation. Some code paths are missing; bugs are
expected at this point.
Related: OS#5502
Change-Id: I588eb576b2703262f4ab9566ec362920d8390cfd