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 :(
Our state transitions and timers now reflect 04.08 for GMM much
better than before. Also, we allocate a new P-TMSI on every ATTACH
and RA UPDATE, as some phones seem to get confused if they don't
get a P-TMSI.
This is of course not the correct way of dealing with it, but for
now it should make the Ericsson Mobile Plafrom based phones happy
(they insist to do a suspend/resume cycle before pdp ctx act)
GRE has the strange notion of keepalive messages being encapsulated IPv4
packets adressed back to the sender. Since we actually really only care
about frame relay, this is a bit strange. However, we'll do some sanity
checks and send it back through our GRE socket...
0 Reserved for ANSI Annex D and CCITT Annex A link management
1 - 15 Reserved
16 - 1007 Any PVC
1008 - 1018 Reserved
1019 - 1022 Reserved for LMI multicast
1023 Reserved for LMI link management
According to the spec, after an incoming RESET or RESET_ACK, we shall start the
TEST procedure, not the ALIVE procedure.
Also, when we start the TEST procedure, we have to always send a NS_ALIVE
packet at the same time (we didn't in the case of incoming RESET).
Furthermore, we now only start TIMER_TNS_ALIVE from within the
TIMER_TNS_RESET callback code, where we also make sure that the
alive_retries counter is reset to zero.
Change gprs_nsvc_reset to return void instead of a int
as the gb_proxy.c currently ignores the reutnr value anyway.
Change the caller inside gprs_ns to return the newly allocated
nsvc instead of the return of gprs_nsvc_reset.
Almost all parameters about the SGSNs NS-VC can be specified in the NS
protocol node. All that needs to remain in the gbproxy config node
is "nsip sgsn nsei XXX".
* store LLC SAPI as part of PDP ctx
* store NSEI + BVCI as part of MM ctx
* export gsm48_tx_gsm_act_pdp_acc() and call it from sgsn_libgtp.c
* create and use gsm48_tx_gsm_act_pdp_rej for error cases
* print SAPI as part of VTY show pdp
libgtp of the OpenGGSN project will allow us to speak the GTPv0/v1
protocol of the interface between SGSN and GGSN.
This commit includes code for the main libgtp integration (file
descriptor, select loop, timer) as well as code to encode/send
a CREATE PDP CONTEXT request.
We want the VTY and telnet code to be independent from the BSC
application(s). As a side note, we also like to eliminate static
global variables for 'struct gsm_network' all over the code.
As such, telnet_init() is now passed along a "private" pointer,
which getst stored in telnet_connection.priv. This telnet_connection
is then stored in vty->priv, which in turn gets dereferenced if
anyone needs a reference to 'struct gsm_network' from the BSC vty
code.
Also:
* vty_init() now calls cmd_init()
* the ugliness that telnet_init() calls back into the application by means of
bsc_vty_init() function has been removed.
* telnet_init() now returns any errors, so the main program can exit
e.g. if the port is already in use.
This enables us to make the VTY completely independent of any
compile-time program-specific information, i.e. one step closer
to using VTY as a shared library from multiple programs.
Rather than deleting the NSE from memory, we simply mark it as non-persistent.
This makes sure that there are no invalid references (e.g. from gbprox_peer)
to the gprs_nsvc structure, but at the same time ensures it will no longer
be stored as part of writing the config file.
So far, we only started the ALIVE procedure on RESET-ACK if the
remote end was the SGSN. This resulted in the BSS->Proxy connections
only being tested for alive-status from the BSS side, but not from
our side.
Also: export nsvc_by_nsvci() function as a public API function.
Using "end" you can always return to the "enable" level, and from
there the "show" commands are available. So no more need for
exit/exit/exit/exit/disable.
Some BSS that connect to the proxy do not continue to perform the
RESET procedure after a timeout. In order to resurrect them, we
simply start a RESET procedure.
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.