hnb-test: comment on gen_initue_lu() IMSI
diff --git a/src/tests/hnb-test.c b/src/tests/hnb-test.c
index e836830..1f0685a 100644
--- a/src/tests/hnb-test.c
+++ b/src/tests/hnb-test.c
@@ -554,6 +554,19 @@
struct msgb *msg;
/* FIXME: patch imsi */
+ /* Note: the Mobile Identitiy IE's IMSI data has the identity type and
+ * an even/odd indicator bit encoded in the first octet. So the first
+ * octet looks like this:
+ *
+ * 8 7 6 5 | 4 | 3 2 1
+ * IMSI-digit | even/odd | type
+ *
+ * followed by the remaining IMSI digits.
+ * If digit count is even (bit 4 == 0), that first high-nibble is 0xf.
+ * (derived from Iu pcap Location Update Request msg and TS 25.413)
+ *
+ * TODO I'm only 90% sure about this
+ */
return ranap_new_msg_initial_ue(conn_id, is_ps, &rnc_id, lu, sizeof(lu));
}