SGSN: Integrate support for UMTS AKA

The general infrastructure for UMTS AKA is already in place:
* GSUP with capability to send us auth_vectors that contain
  either triplets or quintuples
* mm_context that holds such auth_vectors

Add:
* capability to send UMTS AUTN in GMM AUTH REQ
* parse extended UMTS RES
* on auth response, validate expected AKA with vector and received res/sres
* add Auth Failure message to receive resync AUTS token and
  * send to HLR
  * clear out-of-sync auth tuple
  * enter new state for when we're waiting for HLR to resync and send new
    tuples so that the next Auth Request will be handled

Original first half of this patch by: Harald Welte <laforge@gnumonks.org>

Full UMTS AKA procedure including AUTS resync tested to work against OsmoHLR
with R99 USIM and Milenage algorithm.

The sgsn_test.c needs adjustment because we're checking the vector's auth_types
now.

Depends: libosmocore change-ids
         I277fb3d407396dffa5c07a9c5454d87a415d393f
         If943731a78089f0aac3d55245de80596d01314a4
Related: OS#1956
Change-Id: Ie6a0cefba5e4e7f02cc2eaf6ec006ac07d5c1816

1 files changed, 21 insertions, 5 deletions

diff --git a/openbsc/src/gprs/gprs_subscriber.c b/openbsc/src/gprs/gprs_subscriber.c
index 5f426f80c..2042ec6eb 100644
--- a/openbsc/src/gprs/gprs_subscriber.c
+++ b/openbsc/src/gprs/gprs_subscriber.c
@@ -766,14 +766,21 @@ int gprs_subscr_purge(struct gprs_subscr *subscr)
 	return gprs_subscr_tx_gsup_message(subscr, &gsup_msg);
 }
 
-int gprs_subscr_query_auth_info(struct gprs_subscr *subscr)
+static int gprs_subscr_query_auth_info(struct gprs_subscr *subscr,
+				       const uint8_t *auts,
+				       const uint8_t *auts_rand)
 {
 	struct osmo_gsup_message gsup_msg = {0};
 
-	LOGGSUBSCRP(LOGL_INFO, subscr,
-		"subscriber auth info is not available\n");
+	/* Make sure we have a complete resync or clearly no resync. */
+	OSMO_ASSERT((auts != NULL) == (auts_rand != NULL));
+
+	LOGGSUBSCRP(LOGL_INFO, subscr, "requesting auth info%s\n",
+		    auts ? " with AUTS (UMTS Resynch)" : "");
 
 	gsup_msg.message_type = OSMO_GSUP_MSGT_SEND_AUTH_INFO_REQUEST;
+	gsup_msg.auts = auts;
+	gsup_msg.rand = auts_rand;
 	return gprs_subscr_tx_gsup_message(subscr, &gsup_msg);
 }
 
@@ -854,7 +861,16 @@ int gprs_subscr_request_update_location(struct sgsn_mm_ctx *mmctx)
 	return rc;
 }
 
-int gprs_subscr_request_auth_info(struct sgsn_mm_ctx *mmctx)
+/*! \brief Send Update Auth Info request via GSUP, with or without resync.
+ *  \param[in] mmctx  MM context to request authentication tuples for.
+ *  \param[in] auts  14 octet AUTS token for UMTS resync, or NULL.
+ *  \param[in] auts_rand  16 octet Random token for UMTS resync, or NULL.
+ * In case of normal Authentication Info request, both \a auts and \a auts_rand
+ * must be NULL. For resync, both must be non-NULL.
+ */
+int gprs_subscr_request_auth_info(struct sgsn_mm_ctx *mmctx,
+				  const uint8_t *auts,
+				  const uint8_t *auts_rand)
 {
 	struct gprs_subscr *subscr = NULL;
 	int rc;
@@ -865,7 +881,7 @@ int gprs_subscr_request_auth_info(struct sgsn_mm_ctx *mmctx)
 
 	subscr->flags |= GPRS_SUBSCRIBER_UPDATE_AUTH_INFO_PENDING;
 
-	rc = gprs_subscr_query_auth_info(subscr);
+	rc = gprs_subscr_query_auth_info(subscr, auts, auts_rand);
 	gprs_subscr_put(subscr);
 	return rc;
 }