Bluetooth: Host: Fix bt_addr_from_str for str starting with ':'

The previous implementation would read from `addr->val[0]` before it was
initialized if the input string started with a colon ':'.

Signed-off-by: Aleksander Wasaznik <aleksander.wasaznik@nordicsemi.no>

include/zephyr/bluetooth/addr.h

@@ -272,7 +272,8 @@ static inline int bt_addr_le_to_str(const bt_addr_le_t *addr, char *str,
  *  @param[in]  str   The string representation of a Bluetooth address.
  *  @param[out] addr  Address of buffer to store the Bluetooth address
  *
- *  @return Zero on success or (negative) error code otherwise.
+ *  @retval 0 Success. The parsed address is stored in @p addr.
+ *  @return -EINVAL Invalid address string. @p str is not a well-formed Bluetooth address.
  */
 int bt_addr_from_str(const char *str, bt_addr_t *addr);
 

subsys/bluetooth/host/addr.c

@@ -53,28 +53,33 @@ int bt_addr_le_create_static(bt_addr_le_t *addr)
 
 int bt_addr_from_str(const char *str, bt_addr_t *addr)
 {
-	int i, j;
-	uint8_t tmp;
+	/* Parse a null-terminated string with a Bluetooth address in
+	 * canonical "XX:XX:XX:XX:XX:XX" format.
+	 */
 
-	if (strlen(str) != 17U) {
+	const size_t len = strlen(str);
+
+	/* Verify length. */
+	if (len != BT_ADDR_STR_LEN - 1) {
 		return -EINVAL;
 	}
 
-	for (i = 5, j = 1; *str != '\0'; str++, j++) {
-		if (!(j % 3) && (*str != ':')) {
+	/* Verify that all the colons are present. */
+	for (size_t i = 2; i < len; i += 3) {
+		if (str[i] != ':') {
 			return -EINVAL;
-		} else if (*str == ':') {
-			i--;
-			continue;
 		}
+	}
 
-		addr->val[i] = addr->val[i] << 4;
+	/* Parse each octet as hex and populate `addr->val`. It must be
+	 * reversed since `bt_addr_t` is in 'on-air' format.
+	 */
+	for (size_t i = 0; i < ARRAY_SIZE(addr->val); i++) {
+		const size_t reverse_i = ARRAY_SIZE(addr->val) - 1 - i;
 
-		if (char2hex(*str, &tmp) < 0) {
+		if (!hex2bin(&str[i * 3], 2, &addr->val[reverse_i], 1)) {
 			return -EINVAL;
 		}
-
-		addr->val[i] |= tmp;
 	}
 
 	return 0;