Add helper function for generating random MAC addresses with same OUI

random_mac_addr_keep_oui() is similar to random_mac_addr(), but it
maintains the OUI part of the source address.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/utils/common.c

@@ -856,3 +856,13 @@ int random_mac_addr(u8 *addr)
 	addr[0] |= 0x02; /* locally administered */
 	return 0;
 }
+
+
+int random_mac_addr_keep_oui(u8 *addr)
+{
+	if (os_get_random(addr + 3, 3) < 0)
+		return -1;
+	addr[0] &= 0xfe; /* unicast */
+	addr[0] |= 0x02; /* locally administered */
+	return 0;
+}

src/utils/common.h

@@ -539,6 +539,7 @@ void str_clear_free(char *str);
 void bin_clear_free(void *bin, size_t len);
 
 int random_mac_addr(u8 *addr);
+int random_mac_addr_keep_oui(u8 *addr);
 
 
 /*