osmo-auc-gen: clarify SQN output, prepare for SQN changes

Upcoming patches will change the way SQN are incremented. Change the SQN
related output by osmo-auc-gen so that it also makes sense after these changes,
and so that its output is proven to remain unchanged for the same arguments:

Always show the SQN used for vector generation when a UMTS vector was generated.

Don't show the next SQN, it will not make sense anymore (see later patches).

The adjustments of expected output of osmo-auc-gen_test illustrates how the
output changes.

Related: OS#1968
Change-Id: I35d9c669002ff3e8570e07b444cca34ce57c3b0c
diff --git a/utils/osmo-auc-gen.c b/utils/osmo-auc-gen.c
index f0cfa79..6fa7cec 100644
--- a/utils/osmo-auc-gen.c
+++ b/utils/osmo-auc-gen.c
@@ -257,24 +257,19 @@
 
 	if (fmt_triplets_dat)
 		dump_triplets_dat(vec);
-	else
+	else {
 		dump_auth_vec(vec);
+		if (test_aud.type == OSMO_AUTH_TYPE_UMTS)
+			/* After generating, SQN is incremented, so -1 */
+			printf("SQN:\t%" PRIu64 "\n", test_aud.u.umts.sqn - 1);
+	}
 
-	/* Print SQN from AUTS. It makes sense to print actually three SQN
-	 * to clarify:
-	 * After recovering SQN.MS from AUTS, milenage_gen_vec_auts() does:
-	 *   aud->u.umts.sqn = 1 + (osmo_load64be_ext(sqn_out, 6) >> 16);
-	 * Then calls milenage_gen_vec(), which, after it is done, does:
-	 *   aud->u.umts.sqn++;
-	 */
+	/* After recovering SQN.MS from AUTS, milenage_gen_vec_auts() does
+	 * aud->u.umts.sqn++, and after vector generation milenage_gen_vec()
+	 * does another ++, so to show SQN.MS we need to -2 */
 	if (auts_is_set)
-		printf("AUTS success: SQN.MS = %" PRIu64
-		       ", generated vector with SQN = %" PRIu64
-		       ", next SQN = %" PRIu64 "\n",
-		       test_aud.u.umts.sqn - 2,
-		       test_aud.u.umts.sqn - 1,
-		       test_aud.u.umts.sqn
-		       );
+		printf("AUTS success: SQN.MS = %" PRIu64 "\n",
+		       test_aud.u.umts.sqn - 2);
 
 	exit(0);
 }