We now actually are much more in line with what the specification
says. We track the blocked/unblocked state, we don't accept
signalling messages on PTP functional entities (and vice versa),
and we don't simply create a BVC context with messages other than
BVC-RESET.
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.
In the previous code we used a static fake_nsvc structure in
case we needed to send a message to an unknown NSVC for which
we don't have a real 'struct nsvc'. However, since we now have
a rate_ctr_group hanging off the nsvc, the fake structure didn't
have that.
So now we keep a nsi->unknown_nsvc around to be used whenever
we need a nsvc but don't have a real one. The gprs_ns_vty.c
code explicitly does not list that NSVC in 'show ns'
Every NS-VC now has a set of counters for incoming and outgoing
number of packets and bytes.
We also split the VTY part of the gprs_ns.c implementation into gprs_ns_vty.c
to make sure the protocol can actually be used without the VTY code being
present.
As only NS-UNITDATA messages are ever passed into the Gb Proxy,
we need to do the msgb_free() at a much higher point in the calling
stack, i.e. inside the NS protocol layer. This means it is now
the same logic as in OpenBSC itself.
The old idea was to take a msgb from gbprox_rcvmsg() and then
modify it and finally send it all the way down to nsip_sendmsg()
to the remote peer.
However, this introduces memory management difficulties, as we then
have to distinguish three cases:
* msgb was sent to a remote peer
* we sent some error message and need to free the msgb
* we need to make n-1 copies in case of a BSSVC-RESET from the SGSN
So instead we now simply always copy the message if we pass it on.
All messages received by gbprox_rcvmsg() are msgb_free()d in the very
same routine
All messages allocated by tx2peer() or tx2sgsn() are freed after
nsip_sendmsg()
With persistent NS-VC configuration (configured through VTY),
we can respond properly to BSS with a somewhat strange NS
implementation Such as the BSplus. It enables us to respond
with a proper NS-RESET (including NSVCI/NSEI) when receiving
a NS-ALIVE or other PDU for a BLOCKED/DEAD NS-VC after our
end of the connection is rebooted.
If a PTP BVC is BVC-RESET by the BSS, the PDU contains the
Cell Identifier. We can snoop this into our gbprox_peer structure
for better visualization of each peer in they vty.
In order to reuse the existing bssgp_tx_* functions without pulling
in the dependencies of gprs_bssgp.c, we have to move those functions
to gprs_bssgp_util.c
Furthermore, we can remove gbprox_nsi and replace it with bssgp_nsi,
and we can do proper processing of BVC-RESET messages coming from
the SGSN on the signalling BVC. In that case we need to send RESET
messages to all the BSS.