Obtaining the DUID of a computer

#include <stdafx.h>
#include <winsock2.h>
#include <iphlpapi.h>
#include <stdio.h>
#include <iostream>
using namespace std;

#pragma comment(lib, "IPHLPAPI.lib")

#define MALLOC(x) HeapAlloc(GetProcessHeap(), 0, (x))
#define FREE(x) HeapFree(GetProcessHeap(), 0, (x))

/* Note: could also use malloc() and free() */

int __cdecl main(int argc, char **argv)
{

    /* Declare and initialize variables */

    DWORD dwSize = 0;
    DWORD dwRetVal = 0;

    unsigned int i = 0;

    // Set the flags to pass to GetAdaptersAddresses
    ULONG flags = GAA_FLAG_INCLUDE_PREFIX;

    // default to unspecified address family (both)
    ULONG family = AF_UNSPEC;

    LPVOID lpMsgBuf = NULL;

    PIP_ADAPTER_ADDRESSES pAddresses = NULL;
    ULONG outBufLen = 0;

    PIP_ADAPTER_ADDRESSES pCurrAddresses = NULL;
    PIP_ADAPTER_UNICAST_ADDRESS pUnicast = NULL;
    PIP_ADAPTER_ANYCAST_ADDRESS pAnycast = NULL;
    PIP_ADAPTER_MULTICAST_ADDRESS pMulticast = NULL;
    IP_ADAPTER_DNS_SERVER_ADDRESS *pDnServer = NULL;
    IP_ADAPTER_PREFIX *pPrefix = NULL;

    family = AF_INET6;

    outBufLen = sizeof (IP_ADAPTER_ADDRESSES);
    pAddresses = (IP_ADAPTER_ADDRESSES *) MALLOC(outBufLen);

    // Make an initial call to GetAdaptersAddresses to get the 
    // size needed into the outBufLen variable
    if (GetAdaptersAddresses(family, flags, NULL, pAddresses, &outBufLen) == ERROR_BUFFER_OVERFLOW) {
        FREE(pAddresses);
        pAddresses = (IP_ADAPTER_ADDRESSES *) MALLOC(outBufLen);
    }

    if (pAddresses == NULL) {
        printf("Memory allocation failed for IP_ADAPTER_ADDRESSES struct\n");
        exit(1);
    }
    // Make a second call to GetAdapters Addresses to get the
    // actual data we want
    printf("Calling GetAdaptersAddresses function with family = ");
    if (family == AF_INET)
        printf("AF_INET\n");
    if (family == AF_INET6)
        printf("AF_INET6\n");
    if (family == AF_UNSPEC)
        printf("AF_UNSPEC\n\n");

    dwRetVal = GetAdaptersAddresses(family, NULL, NULL, pAddresses, &outBufLen);

    if (dwRetVal == NO_ERROR) {
        // If successful, output some information from the data we received
        pCurrAddresses = pAddresses;		
        while (pCurrAddresses) {
			if(pCurrAddresses->Dhcpv6ClientDuidLength){
			if (pCurrAddresses->PhysicalAddressLength != 0) {
                printf("\tPhysical address: ");
                for (i = 0; i < pCurrAddresses->PhysicalAddressLength;
                     i++) {
                    if (i == (pCurrAddresses->PhysicalAddressLength - 1))
                        printf("%.2X\n",(int) pCurrAddresses->PhysicalAddress[i]);
                    else
                        printf("%.2X-",(int) pCurrAddresses->PhysicalAddress[i]);
                }
			}
			
			if (pCurrAddresses->Dhcpv6ClientDuidLength != 0) {
                printf("\tDUID: ");
                for (i = 0; i < (int) pCurrAddresses->Dhcpv6ClientDuidLength;i++) {
                    if (i == (pCurrAddresses->Dhcpv6ClientDuidLength - 1))
                        printf("%.2X\n",(int) pCurrAddresses->Dhcpv6ClientDuid[i]);
                    else
                        printf("%.2X-",(int) pCurrAddresses->Dhcpv6ClientDuid[i]);
                }
            }
			printf("\n");
			}
            pPrefix = pCurrAddresses->FirstPrefix;
            pCurrAddresses = pCurrAddresses->Next;
        }
    } else {
        printf("Call to GetAdaptersAddresses failed with error: %d\n",dwRetVal);
        if (dwRetVal == ERROR_NO_DATA)
            printf("\tNo addresses were found for the requested parameters\n");
        else {

            if (FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, dwRetVal, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),   // Default language
                              (LPTSTR) & lpMsgBuf, 0, NULL)) {
                printf("\tError: %s", lpMsgBuf);
                LocalFree(lpMsgBuf);
                FREE(pAddresses);
                exit(1);
            }
        }
    }
    FREE(pAddresses);
	system ("pause");
    return 0;
}