How do you validate that a string is a valid MAC address in C?

Question

example:

12:45:ff:ab:aa:cd    is valid
45:jj:jj:kk:ui>cd    is not valid

Answer 1

Here is another simple function to check sanity of MAC address

#include 
#include 

typedef unsigned char byte;

#define ETH_ADDR_LEN    6
#define FALSE           0
#define TRUE            1
#define MAC_STR_LEN     18
#define SEPERATOR       ':'

int isMacValid(char *MacAddress) {
    char mac_part[3] = {0};
    byte mac_byte    = 0;
    byte mac_idx     = 0;

    while(MacAddress[mac_idx] != 0 && mac_idx < MAC_STR_LEN){
        if(mac_idx != 15 && MacAddress[mac_idx + 2] != SEPERATOR)
            return FALSE;
        strncpy(mac_part, MacAddress+mac_idx,2);
        mac_byte = (byte)strtol(mac_part, NULL, 16);
        if(mac_byte == 0 && strcmp(mac_part,"00"))
            return FALSE;
        mac_idx += 3;
    }

    if(mac_idx == MAC_STR_LEN)
        return TRUE;
    return FALSE;
}