hnbap: accept UE Register Requests with TMSI and pTMSI
Add the option to allow UE Register Requests with a TMSI identity.
Add VTY command to enable this option, 'hnbap-allow-tmsi'.
Add hnbgw_tx_ue_register_acc_tmsi().
HNBGW so far keeps track of UEs that have registered, with their IMSI. When a
UE registers with only a TMSI, we obviously can't store an IMSI. However, since
we're so far never *using* the list of UEs in osmo-hnbgw, we might as well just
accept the TMSI registration and carry on as usual. All that is needed for
proper operation is a valid UE context.
This is aimed at the ip.access nano3G femto cell, as it apparently feeds
whichever identification the UE sends through to HNBAP (TMSI+LAI, pTMSI+RAI),
instead of an IMSI as expected. So far this caused failures and the need to
make the UE clear its TMSI (wait several minutes or attempt to subscribe to a
different network), so that UE registration switched back to IMSI. When simply
accepting the TMSI in osmo-hngw, no problems are apparent in our current code
state.
For example, a Samsung Galaxy S4 seems to send a UE_Identity_PR_tMSILAI (CS
identity), and a GT-I9100 seems to send a UE_Identity_PR_pTMSIRAI (PS identity)
upon first registration to the network.
Recording the IMSI in hnbgw: we could use the subscriber list during paging, to
page a UE on only its last seen HNB. On the other hand, it doesn't hurt to
anyway always page to all HNBs connected to osmo-hnbgw. The paging procedure
does include a page-to-all-HNBs in case the first HNB paging fails. But we must
be aware that UEs that register by TMSI will simply not have an IMSI recorded
in the list of UE contexts, so a lookup based on IMSI may fail.
Patch-by: Harald Welte <laforge@gnumonks.org>, me
Change-Id: I87bc1aa3e85815ded7ac1dbdca48f1680b468589
diff --git a/include/osmocom/iuh/hnbgw.h b/include/osmocom/iuh/hnbgw.h
index bee7fb6..dfe287c 100644
--- a/include/osmocom/iuh/hnbgw.h
+++ b/include/osmocom/iuh/hnbgw.h
@@ -117,6 +117,7 @@
* plane traffic from HNBs */
uint16_t iuh_cs_mux_port;
uint16_t rnc_id;
+ bool hnbap_allow_tmsi;
} config;
/*! SCTP listen socket for incoming connections */
struct osmo_stream_srv_link *iuh;