Fix routing of RADIO-STATUS by TMSI
While development of test cases (specifically
TC_radio_status_tmsi) it has shown that routing the uplink RADIO-STATUS by TMSI is broken. osmo-gbproxy consistently selects a "wrong" SGSN.
The expectation is that we treat the TMSI identical to a TLLI and extract the NRI value from that. However, that somehow fails as the TMSI upper bits are not well-defined and could indicate an unexpected TLLI type. In my examples, it's
tMSI_Value := '42180023'O, whihc contains NRI=3 and hence is expected to end up on SGSN0. However, it gets routed to SGSN1 in all test invocations.
gbproxy: Improve log messages in gbproxy_select_sgsn
gbproxy: Fix radio status routing by TMSI
If a radio status message contains a TMSI it should be routed as if it
was a TLLI. Convert the TMSI to (foreign) TLLI so NRI-routing works.
Both foreign and local TLLIs are routed the same.