Question on Uplink 'sequence count' handling in MME

Hi Sukchan and list, I'm currently reading the MME code and I'm having some trouble understanding the handling of the uplink counter for NAS security. I only see mme_ue->ul_count.i32 ever being set to '0' when a new security context is used. But I don't see it ever being incremented? I only see ul_count.sqn incremented, but then the nas_mac_calculate() always gets ul_count.i32 passed as input. So I'm somehow not understanding how the MAC can ever verify on any uplink message beyond/after the first one which establishes a new security context. What am I missing? Thanks for your insight! -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)