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.
When gprs_ns_sendmsg() succeeds in sending the message, we free()d the
msgb after transmitting it on the socket. However, if the NS-VC is
blocked or some other error condition exists, we returned an error
code but didn't free the msgb.
This resulted in an error leak which is now being addressed.
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.
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.
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.
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.
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.
Harald Welte
Holger Hans Peter Freyther