tree e90c99ff795d14d96ff37c358179a9e5581bbcab
parent d781c7a153c552bc47f9af321f83b9273de2d33d
author Jacob Erlbeck <jerlbeck@sysmocom.de> 1409920356 +0200
committer Holger Hans Peter Freyther <holger@moiji-mobile.com> 1414403436 +0100

sgsn: Send detach(re-attach) instead of gmm status if TLLI unknown

The osmo-sgsn sends Status messages (or nothing in case of non
GMM/GSM) when the TLLI is unknown. This prevents the MS from
reconnecting.

This patch adds the initiation of an MT detach procedure to force a
re-attach to set up a valid LLE context if an LLE or an MM context
cannot be found. Since this can also be triggered by non-GMM SAPI
messages, a GPRS application callback sgsn_force_reattach_oldmsg is
added which in turn calls the GMM layer to generate the GSM 04.08
specific messages.

Note that the MS can be left in REGISTERED state after initially
wanting to detach itself, since it will receive a Detach Req
(re-attach) when sending a DEACT PDP CTX REQ after the SGSN or
gbproxy (P-TMSI patching enabled) has been restarted. This same
behaviour has been observed with another SGSN.

Sponsored-by: On-Waves ehf