Windows 根据MAC地址获得MTU

getInterfaceMTUByMAC.c

/*
 * For Windows Only
 * Find the network interface whose MAC address is "macstr", return the MTU size of this interface.
 *
 * Input parameters:
 * ----macstr: IP address
 * ----macsize: the buffer size of macstr
 *
 * Output parameters:
 *     None
 *
 * Return value:
 *     MTU size
 */
static int
getInterfaceMTUByMAC(const char *macstr, int macsize)
{
    static char fname[] = "getInterfaceMTUByMAC()";

    int ret = -1;

    // Declare and initialize variables.
    DWORD dwSize = 0;
    DWORD dwRetVal = 0;

    unsigned int i;

    /* variables used for GetIfTable and GetIfEntry */
    MIB_IFTABLE *pIfTable;
    MIB_IFROW *pIfRow;

    // Allocate memory for our pointers.
    pIfTable = (MIB_IFTABLE *)HeapAlloc(GetProcessHeap(), 0, (sizeof(MIB_IFTABLE)));
    if (pIfTable == NULL) {
        ls_syslog(LOG_ERR, "%s: Error allocating memory needed to call GetIfTable.", fname);
        return -1;
    }

    // Make an initial call to GetIfTable to get the
    // necessary size into dwSize
    dwSize = sizeof(MIB_IFTABLE);
    if (GetIfTable(pIfTable, &dwSize, FALSE) == ERROR_INSUFFICIENT_BUFFER) {
        HeapFree(GetProcessHeap(), 0, (pIfTable));
        pIfTable = (MIB_IFTABLE *)HeapAlloc(GetProcessHeap(), 0, (dwSize));
        if (pIfTable == NULL) {
            ls_syslog(LOG_ERR, "%s: Error allocating memory needed to call GetIfTable.", fname);
            return -1;
        }
    }

    // Make a second call to GetIfTable to get the actual
    // data we want.
    if ((dwRetVal = GetIfTable(pIfTable, &dwSize, FALSE)) == NO_ERROR) {

        for (i = 0; i < pIfTable->dwNumEntries; i++) {
            pIfRow = (MIB_IFROW *)& pIfTable->table[i];

            if (MAC_ADDRESS_LENGTH == pIfRow->dwPhysAddrLen) {
                char thisAdptMAC[MAC_MAX_SZIE];
                memset(thisAdptMAC, 0 , sizeof(thisAdptMAC));
                sprintf(thisAdptMAC, "%02x:%02x:%02x:%02x:%02x:%02x",
                    pIfRow->bPhysAddr[0],
                    pIfRow->bPhysAddr[1],
                    pIfRow->bPhysAddr[2],
                    pIfRow->bPhysAddr[3],
                    pIfRow->bPhysAddr[4],
                    pIfRow->bPhysAddr[5]
                    );

                if ( 0 == strncmp(thisAdptMAC, macstr, MAC_MAX_SZIE)) {
                    ret = pIfRow->dwMtu;
                }
            }
        }
    } else {
        ls_syslog(LOG_ERR, "%s: GetIfTable failed with error: %d", fname, dwRetVal);
        if (pIfTable != NULL) {
            HeapFree(GetProcessHeap(), 0, (pIfTable));
            pIfTable = NULL;
        }
        ret = -1;
        // Here you can use FormatMessage to find out why 
        // it failed.
    }
    if (pIfTable != NULL) {
        HeapFree(GetProcessHeap(), 0, (pIfTable));
        pIfTable = NULL;
    }

    return ret;
}