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()
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.
Harald Welte