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authorNeels Hofmeyr <neels@hofmeyr.de>2020-06-10 17:31:18 +0200
committerneels <nhofmeyr@sysmocom.de>2020-06-14 10:52:48 +0000
commit16617816114f31bc9560c9646b4f566259f3b4a3 (patch)
tree167f668e4ae0d8a7424259e2029b64253ae5ee8e
parent15a850123243701c538dd110719ce5789820029e (diff)
fix f_enc_IMEI_L3() oddevenIndicator
f_gen_imei() calls f_enc_IMEI_L3() with a 14 digits argument, but the IMEI_L3 template used is hardcoded to 15 digits. So the oddevenIndicator must always indicate odd, not depend on the digits argument. f_gen_imei() should probably also compose a Luhn checksum, leaving that to another patch. Found by using the new osmo_mobile_identity API in osmo-msc, which is stricter about odd/even and filler digits than our previous implementations. See osmo-msc Idfc8e576e10756aeaacf5569f6178068313eb7ea . Change-Id: Iaa9ba1214c4c15fd9620e68fe2e842fdf52912c0
-rw-r--r--library/L3_Templates.ttcn19
1 files changed, 14 insertions, 5 deletions
diff --git a/library/L3_Templates.ttcn b/library/L3_Templates.ttcn
index 3032503..ba91180 100644
--- a/library/L3_Templates.ttcn
+++ b/library/L3_Templates.ttcn
@@ -184,11 +184,20 @@ private function f_enc_IMSI_L3(hexstring digits) return IMSI_L3 {
private function f_enc_IMEI_L3(hexstring digits) return IMEI_L3 {
var IMEI_L3 l3;
var integer len := lengthof(digits);
- if (len rem 2 == 1) { /* modulo remainder */
- l3.oddevenIndicator := '1'B;
- } else {
- l3.oddevenIndicator := '0'B;
- }
+ /* IMEI_L3 is always 15 digits. That is actually a 14 digit IMEI + a Luhn checksum digit (see
+ * libosmocore/include/osmocom/gsm/protocol/gsm_23_003.h)
+ *
+ * Here, we must not make the oddevenIndicator depend on the 'digits' parameter, because:
+ * - The IMEI_L3 template assumes always 15 digits.
+ * - The 'digits' parameter, however, may also contain less digits, 14 in the case of
+ * f_gen_imei().
+ * - The IMEI_L3 template will then fill up with zeros to make 15 digits.
+ * Hence oddevenIndicator must always indicate 'odd' == '1'B.
+ *
+ * FIXME: if the caller passes less than 15 digits, the Luhn checksum digit then ends up zero == most probably
+ * wrong.
+ */
+ l3.oddevenIndicator := '1'B;
l3.digits := digits;
return l3;
}