Invalid MAC-address API

#include<stdio.h>
#define MAC_LEN 6
int is_null_mac(unsigned int *mac)
{
    unsigned int null_mac[MAC_LEN] = {0, 0, 0, 0, 0, 0};

    return (!(mac && (memcmp(mac, null_mac, sizeof(null_mac)) != 0)));
}
int main()
{
    int ret = 0;
    //char *get_mac = "01005E010106";
    char *get_mac = "000000000000";
    unsigned int mac_addr[MAC_LEN] = {0};
    char final[18] = "0";

    sscanf(get_mac, "%02X%02X%02X%02X%02X%02X \t", &mac_addr[0],&mac_addr[1],&mac_addr[2],&mac_addr[3],&mac_addr[4],&mac_addr[5]);
    ret = is_null_mac(mac_addr);

    snprintf(final, sizeof(final),"%02X:%02X:%02X:%02X:%02X:%02X \t", mac_addr[0],mac_addr[1],mac_addr[2],mac_addr[3],mac_addr[4],mac_addr[5]);
    if (ret == 1) {
        printf("Mac:[%s] is NULL \n", final);
    } else {
        printf("Mac:[%s] is not NULL \n", final);
    }

    return 1;
}

Output:

Mac:[00:00:00:00:00:00] is NULL

Program for valid MAC

#include<stdio.h>
#define MAC_LEN 6
int is_null_mac(unsigned int *mac)
{
    unsigned int null_mac[MAC_LEN] = {0, 0, 0, 0, 0, 0};

    return (!(mac && (memcmp(mac, null_mac, sizeof(null_mac)) != 0)));
}
int main()
{
    int ret = 0;
    char *get_mac = "01005E010106";
    //char *get_mac = "000000000000";
    unsigned int mac_addr[MAC_LEN] = {0};
    char final[18] = "0";

    sscanf(get_mac, "%02X%02X%02X%02X%02X%02X \t", &mac_addr[0],&mac_addr[1],&mac_addr[2],&mac_addr[3],&mac_addr[4],&mac_addr[5]);
    ret = is_null_mac(mac_addr);

    snprintf(final, sizeof(final),"%02X:%02X:%02X:%02X:%02X:%02X \t", mac_addr[0],mac_addr[1],mac_addr[2],mac_addr[3],mac_addr[4],mac_addr[5]);
    if (ret == 1) {
        printf("Mac:[%s] is NULL \n", final);
    } else {
        printf("Mac:[%s] is not NULL \n", final);
    }

    return 1;
}

Output:

Mac:[01:00:5E:01:01:06] is not NULL