[PATCH] Addditional classmark check against A5/X support

Max Suraev Max.Suraev at fairwaves.co
Mon Jun 16 20:48:37 UTC 2014


Signed-off-by: Max Suraev <Max.Suraev at fairwaves.co>
---
 include/osmocom/gsm/gsm_utils.h | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/include/osmocom/gsm/gsm_utils.h b/include/osmocom/gsm/gsm_utils.h
index 6eab7ac..cf174e2 100644
--- a/include/osmocom/gsm/gsm_utils.h
+++ b/include/osmocom/gsm/gsm_utils.h
@@ -117,17 +117,41 @@ int rxlev2dbm(uint8_t rxlev);
 uint8_t dbm2rxlev(int dbm);
 
 /* According to GSM 04.08 Chapter 10.5.1.6 */
-static inline int ms_cm2_a5n_support(uint8_t *cm2, int n) {
+static inline int ms_cm2_a5n_support(uint8_t *cm2, unsigned n) {
 	switch (n) {
 		case 0: return 1;
 		case 1: return (cm2[0] & (1<<3)) ? 0 : 1;
 		case 2: return (cm2[2] & (1<<0)) ? 1 : 0;
 		case 3: return (cm2[2] & (1<<1)) ? 1 : 0;
 		default:
-			return 0;
+			return (n > 7) ? 0 : -1;
 	}
 }
 
+/* According to GSM 04.08 Chapter 10.5.1.7 */
+static inline int ms_cm3_a5n_support(uint8_t *cm3, unsigned n) {
+	switch (n) {
+		case 4: return (cm3[0] & (1<<0)) ? 1 : 0;
+		case 5: return (cm3[0] & (1<<1)) ? 1 : 0;
+		case 6: return (cm3[0] & (1<<2)) ? 1 : 0;
+	        case 7: return (cm3[0] & (1<<3)) ? 1 : 0;
+		default:
+			return (n > 7) ? 0 : -1;
+	}
+}
+
+/*! \brief Check whether MS supports given cipher
+ *  \param[in] cm Classmark data transmitted by MS, cannot be NULL
+ *  \param[in] n Cipher number - A5/n
+ *  \returns 1 if supported, 0 if unsupported, -1 on failures
+ *
+ * Implementation based on specifications from GSM 04.08
+ * parts 10.5.1.6 and 10.5.1.7.
+ */
+static inline int ms_a5n_support(uint8_t *cm, unsigned n) {
+    return ((n < 4) ? ms_cm2_a5n_support(cm, n) : ms_cm3_a5n_support(cm, n));
+}
+
 /* According to GSM 04.08 Chapter 10.5.2.29 */
 static inline int rach_max_trans_val2raw(int val) { return (val >> 1) & 3; }
 static inline int rach_max_trans_raw2val(int raw) {
-- 
1.9.1





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