cscn: implement integrity protection

Upon authentication response, initiate integrity protection for Iu by sending a
Security Mode Command (IK), with hardcoded auth tuple so far.

Implement RANAP event handling to receive Security Mode Complete message,
adding stubs for the other events; in new files osmo-cscn/iucs_ranap.[hc] to
keep RANAP dependencies separate, and particularly out of libmsc.

Upon receiving Security Mode Complete, call the security operation callback
(conn->sec_operation->cb) to complete the Location Update.

Introduce enum integrity_protection_state constants to indicate integrity
protection, record in gsm_subscriber_conn.iu.integrity_protection.

Make subscr_conn_lookup_iu() non-static and declare in iu_cs.h to be able to
call from iucs_ranap.c's Security Mode Complete event.

Implement dummy iu_tx_sec_mode_cmd() to allow tests to build without RANAP
dependencies.

In cscn_main.c, call iucs_rx_ranap_event(), to populate the struct gsm_network
struct with cscn_network explicitly (don't share cscn_network across
compilation scopes because it's ugly).

1 files changed, 6 insertions, 0 deletions

diff --git a/openbsc/tests/libiudummy/iudummy.c b/openbsc/tests/libiudummy/iudummy.c
index 7c5129b33..770bccaa9 100644
--- a/openbsc/tests/libiudummy/iudummy.c
+++ b/openbsc/tests/libiudummy/iudummy.c
@@ -15,3 +15,9 @@ int iu_tx(struct msgb *msg, uint8_t sapi)
 	return 0;
 }
 
+int iu_tx_sec_mode_cmd(struct ue_conn_ctx *uectx, struct gsm_auth_tuple *tp,
+		       int send_ck)
+{
+	LOGP(DLGLOBAL, LOGL_INFO, "iu_tx_sec_mode_cmd() dummy called, NOT transmitting Security Mode Command\n");
+	return 0;
+}