According to TS 08.16, the BSSGP layer needs to specify NSEI and BVCI when
executing the NS UNITDATA REQUEST primitive of the underlying NS layer.
Rather than passing around a pointer to the 'struct gprs_nsvc', we now
have NSEI and BVCI as members of 'struct obsc_msgb_cb' and set them
when BSSGP hands a message down to NS.
NS then does a lookup of the 'gprs_nsvc' based on the NSEI parameter.
* move UDP listener code for NSIP from input/ipaccess.c and into gprs_ns.c
* add PDU type, IE and CAUSE values for later IP based 3GPP TS 48.016
* support multiple NS-VCs and their lookup based on NSVC and sockaddr_in
* maintain the remote_state (blocked/alive) for each NSVC
* introduce the concept of GPRS_NS instances, move all global vars to instance
* remove hardcoded calls to gprs_bssgp_rcvmsg() and replace it by callback
WARNING: This is not finished code. While it will compile, it will not work
yet, as BSSGP needs to be converted to properly indicate the NSVC to which it
needs to send data.
Harald Welte