gsm23003: add osmo_imei_str_valid()
Verify 14 digit and 15 digit IMEI strings. OsmoHLR will use the 14
digit version to check IMEIs before writing them to the DB.
Place the Luhn checksum code in a dedicated osmo_luhn() function, so
it can be used elsewhere.
Related: OS#2541
Change-Id: Id2d2a3a93b033bafc74c62e15297034bf4aafe61
diff --git a/src/gsm/gsm23003.c b/src/gsm/gsm23003.c
index 4fdad48..1d9cefe 100644
--- a/src/gsm/gsm23003.c
+++ b/src/gsm/gsm23003.c
@@ -31,6 +31,7 @@
#include <osmocom/gsm/gsm23003.h>
#include <osmocom/gsm/protocol/gsm_23_003.h>
+#include <osmocom/core/utils.h>
static bool is_n_digits(const char *str, int min_digits, int max_digits)
{
@@ -71,6 +72,23 @@
return is_n_digits(msisdn, 1, 15);
}
+/*! Determine whether the given IMEI is valid according to 3GPP TS 23.003,
+ * Section 6.2.1. It consists of 14 digits, the 15th check digit is not
+ * intended for digital transmission.
+ * \param imei IMEI digits in ASCII string representation.
+ * \param with_15th_digit when true, expect the 15th digit to be present and
+ * verify it.
+ * \returns true when the IMEI is valid, false for invalid characters or number
+ * of digits.
+ */
+bool osmo_imei_str_valid(const char *imei, bool with_15th_digit)
+{
+ if (with_15th_digit)
+ return is_n_digits(imei, 15, 15) && osmo_luhn(imei, 14) == imei[14];
+ else
+ return is_n_digits(imei, 14, 14);
+}
+
/*! Return MCC string as standardized 3-digit with leading zeros.
* \param[in] mcc MCC value.
* \returns string in static buffer.