Cellular Network Infrastructure » Core Network (CN) » OsmoHLR

There is some commented out code in hlr.c, which should cancel the subscriber in the old VLR/SGSN if the subscriber did a location update from a different VLR/SGSN:

https://git.osmocom.org/osmo-hlr/tree/src/hlr.c?id=08358b275288e85663ace12e06924414443b1f7c#n403

The current vlr_number/sgsn_number should be luop->peer, and lu_op_tx_cancel_old() in luop.c needs these changes:

-       //gsup.cause = FIXME;
-       //gsup.cancel_type = FIXME;
+       gsup.cn_domain = luop->is_ps ? OSMO_GSUP_CN_DOMAIN_PS : OSMO_GSUP_CN_DOMAIN_CS;
+       gsup.cancel_type = OSMO_GSUP_CANCEL_TYPE_WITHDRAW;

However, with the current code, lu_op_tx_cancel_old() would send the cancel to the same peer that initiated the location update. But it must be sent to the old peer!

I'm just writing down what I found while looking into something similar for IMSI pseudonymization (#4476).