GSM 04.64 8.4.2 asks to ignore UI frames if the DLCI is not known,
or if the "(V(UR)- 32) <= N(U) < V(UR)". E.g. if we want to have
V(UR) == 511 and this frame is dropped, we would ignore N(U)'s
0 to 510. Calculate the delta.
The code is based on Jonathan Santos's "LLC UI window" fix but the
issue was discovered independly.
Using LLGMM-RESET.req, the GMM can request the LLC of the MS to reset
all its parameters, particularly the sequence numbers. We don't yet do
XID RESET retransmissions, and we don't yet generate a LLGMM-RESET.conf
primitive back to GMM.
libosmogsm is a new library that is distributed in the libosmocore.
Now, openbsc depends on it. This patch gets openbsc with this
change.
This patch also rewrites all include path to the new
osmocom/[gsm|core]
Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>
In case we get a RA UPD REQ on a new cell (both served by the same
SGSN), the LLC stack should not allocate a ne LLE/LLME, as the latter
would reset the V(u)sent / V(u)recv to zero and make the MS discard
our responses.
Instead, whenever the LLC stack sees a foreign TLLI, it should always
convert it to the local TLLI before doing any lookup for a LLE/LLME.
The reason for this is quite simple: We want to make sure anyone
running a customized version of OpenBSC to operate a network will
have to release all custom modifiations to the source code.
The FCS isn't computed yet (because of ciphering).
It _will_ be tested and reported as wrong later in the code
so we can just display it here and let the latter code report the
error if any.
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Once The TLLI (or P-TMSI of which it is derived) change has been
confirmed by the MS, we need to unassign the old TLLI but keep
the new TLLI _without_ re-setting the LLC entity structure such
as VUsend /VUrecv counters.
* separate the LLME and LLE state in the LLC layer
* introduce gprs_llgmm_assign() function for LLGMM-ASSIGN.req primitive
* change QoS profile to match 'real' SGSN
* Update the new TLLI when assigning a P-TMSI
The result now is that the LLC layer is notified of TLLI changes, which in turn
means it doesn't allocate a new LLE structure every TLLI change, which again
in turn means that the UI frame sequence number does not reset to zero.
As a result, MS should no longer ignore frames based on wrong UI sequence number.
When we send a downlink unit-data request via BSSGP, there is a lot
of information that needs to be copied from the mm context, such as
the IMSI, DRX parametes, MS radio access parameters, ...
This is a quite strange layering violation, since we now need to pass
a pointer to the MM ctx from GMM through LLC into BSSGP :(
Don't allocate a LLC Entity just because BSSGP passes any random
SAPI/TLLI up to us. We can only do this for XID and UI frames
of the GMM SAPI.
Furthermore, add more comments and debug messages.
Holger Hans Peter Freyther
Harald Welte
Dieter Spaar
Sylvain Munaut