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Obtaining addresses for the adapters on the local computer (Win XP/2003/Vista)

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See also:
  • SendARP function
  • How to retrieve adapter information for the local computer (including MAC address)
  • Using NetWkstaTransportEnum to obtain MAC Address of remote server
  • How to ping a remote site using IP Helper API calls
  • How to ping a remote site using ICMP API calls

  •  
    #DEFINE AF_UNSPEC 0
    #DEFINE ERROR_SUCCESS 0
    #DEFINE MAX_ADAPTER_ADDRESS_LENGTH 8
    #DEFINE OFFSET_NEXT_STRUPTR 9
     
    DO declare
     
    PRIVATE hBuffer, cBuffer, nBufsize
    nBufsize = 16384  && a sufficient one
    hBuffer = GlobalAlloc(0, nBufsize)
     
    nResult = GetAdaptersAddresses(AF_UNSPEC, 0, 0,;
        hBuffer, @nBufsize)
     
    IF NOT nResult = ERROR_SUCCESS
    * 111=ERROR_BUFFER_OVERFLOW
        ? "Error:", nResult
    ELSE
        cBuffer = REPLICATE(CHR(0), nBufsize)
        = MemToStr(@cBuffer, hBuffer, nBufsize)
     
    *!*    typedef struct _IP_ADAPTER_ADDRESSES {
    *!*      union {
    *!*        ULONGLONG Alignment; 0:8
    *!*        struct {
    *!*              ULONG Length;
    *!*              DWORD IfIndex;
    *!*         };
    *!*      };
    *!*      struct _IP_ADAPTER_ADDRESSES* Next;
    *!*      PCHAR AdapterName;
    *!*      PIP_ADAPTER_UNICAST_ADDRESS FirstUnicastAddress;
    *!*      PIP_ADAPTER_ANYCAST_ADDRESS FirstAnycastAddress;
    *!*      PIP_ADAPTER_MULTICAST_ADDRESS FirstMulticastAddress;
    *!*      PIP_ADAPTER_DNS_SERVER_ADDRESS FirstDnsServerAddress;
    *!*      PWCHAR DnsSuffix;
    *!*      PWCHAR Description;
    *!*      PWCHAR FriendlyName;
    *!*      BYTE PhysicalAddress[MAX_ADAPTER_ADDRESS_LENGTH];
    *!*      DWORD PhysicalAddressLength;
    *!*      DWORD Flags;
    *!*      DWORD Mtu;
    *!*      DWORD IfType;
    *!*      IF_OPER_STATUS OperStatus;
    *!*      DWORD Ipv6IfIndex;
    *!*      DWORD ZoneIndices[16];
    *!*      PIP_ADAPTER_PREFIX FirstPrefix;
    *!*    } IP_ADAPTER_ADDRESSES, *PIP_ADAPTER_ADDRESSES;
     
        LOCAL nOffs2Stru, nOffsNext, nMacAddressLen, cMacAddress,;
            nFlags, nMtu, nIftype, nOperStatus
     
        nOffs2Stru = OFFSET_NEXT_STRUPTR
     
        CREATE CURSOR cs (;
            adaptername C(50),;
            dnssuffix C(30),;
            description C(50),;
            friendlyname C(50),;
            macaddress C(30),;
            flags I, mtu I,;
            iftype I, operstatus I;
        )
     
        DO WHILE .T.
     
            cAdapterName = StrFromPtr(buf2dword(SUBSTR(;
                cBuffer, nOffs2Stru+4, 4)))
     
            cDnsSuffix = WStrFromPtr(buf2dword(SUBSTR(;
                cBuffer, nOffs2Stru+24, 4)))
     
            cDescription = WStrFromPtr(buf2dword(;
                SUBSTR(cBuffer, nOffs2Stru+28, 4)))
     
            cFriendlyName = WStrFromPtr(buf2dword(;
                SUBSTR(cBuffer, nOffs2Stru+32, 4)))
     
            nMacAddressLen = buf2dword(SUBSTR(cBuffer,;
                nOffs2Stru+36+MAX_ADAPTER_ADDRESS_LENGTH, 4))
     
            nMacAddressLen = IIF(nMacAddressLen=0,;
                MAX_ADAPTER_ADDRESS_LENGTH, nMacAddressLen)
     
            cMacAddress = Str2Hex(SUBSTR(cBuffer,;
                nOffs2Stru+36, nMacAddressLen))
     
            nFlags = buf2dword(SUBSTR(cBuffer,;
                nOffs2Stru+36+MAX_ADAPTER_ADDRESS_LENGTH+4, 4))
     
            nMtu = buf2dword(SUBSTR(cBuffer,;
                nOffs2Stru+36+MAX_ADAPTER_ADDRESS_LENGTH+8, 4))
     
            nIftype = buf2dword(SUBSTR(cBuffer,;
                nOffs2Stru+36+MAX_ADAPTER_ADDRESS_LENGTH+12, 4))
     
            nOperStatus = buf2dword(SUBSTR(cBuffer,;
                nOffs2Stru+36+MAX_ADAPTER_ADDRESS_LENGTH+16, 4))
     
            INSERT INTO cs VALUES (cAdapterName, cDnsSuffix,;
                cDescription, cFriendlyName, cMacAddress,;
                nFlags, nMtu, nIftype, nOperStatus)
     
            nOffsNext = buf2dword(SUBSTR(cBuffer, nOffs2Stru, 4))
            IF nOffsNext = 0
                EXIT
            ENDIF
     
            nOffs2Stru = nOffsNext - hBuffer + OFFSET_NEXT_STRUPTR
        ENDDO
     
    ENDIF
     
    = GlobalFree(hBuffer)
    IF USED("cs")
        SELECT cs
        GO TOP
        BROWSE NORMAL NOWAIT
    ENDIF
    * end of main
     
    FUNCTION Str2Hex(cStr)
        LOCAL cResult, nIndex, nAsc
        cResult=""
        FOR nIndex=1 TO LEN(cStr)
            nAsc = ASC(SUBSTR(cStr, nIndex, 1))
            cResult = cResult +;
                IIF(EMPTY(cResult), "", "-") +;
                RIGHT(TRANSFORM(nAsc, "@0"),2)
        NEXT
    RETURN cResult
     
    FUNCTION StrFromPtr(nPtr)
        IF nPtr = 0
            RETURN ""
        ENDIF
     
        LOCAL nOffset, ch, cResult
        nOffset = m.nPtr - hBuffer + 1
        cResult=""
     
        DO WHILE nOffset <= LEN(cBuffer)
            ch = SUBSTR(cBuffer, nOffset, 1)
            IF m.ch = CHR(0)
                EXIT
            ENDIF
            cResult = m.cResult + m.ch
            nOffset = nOffset + 1
        ENDDO
    RETURN m.cResult
     
    FUNCTION WStrFromPtr(nPtr)
        IF nPtr = 0
            RETURN ""
        ENDIF
     
        LOCAL nOffset, ch, cResult
        nOffset = m.nPtr - hBuffer + 1
        cResult=""
     
        DO WHILE nOffset <= LEN(cBuffer)
            ch = SUBSTR(cBuffer, nOffset, 2)
            IF m.ch = CHR(0)+CHR(0)
                EXIT
            ENDIF
            cResult = m.cResult + m.ch
            nOffset = nOffset + 2
        ENDDO
    RETURN STRCONV(m.cResult,6)
     
    PROCEDURE declare
        DECLARE INTEGER GlobalAlloc IN kernel32;
            INTEGER wFlags, INTEGER dwBytes
     
        DECLARE INTEGER GlobalFree IN kernel32 INTEGER hMem
     
        DECLARE RtlMoveMemory IN kernel32 As MemToStr;
            STRING @dst, INTEGER src, INTEGER nLength
     
        DECLARE INTEGER GetAdaptersAddresses IN Iphlpapi;
            LONG Family, LONG flgs, INTEGER Reserved,;
            INTEGER pAdapterAddresses, LONG @pOutBufLen
     
    FUNCTION buf2dword(cBuffer)
    RETURN Asc(SUBSTR(cBuffer, 1,1)) + ;
        BitLShift(Asc(SUBSTR(cBuffer, 2,1)),  8) +;
        BitLShift(Asc(SUBSTR(cBuffer, 3,1)), 16) +;
        BitLShift(Asc(SUBSTR(cBuffer, 4,1)), 24)
     
     
     

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    4705 bytes  
    Created: 2006-02-22 07:51:45  
    Modified: 2009-02-15 19:51:45  
    Visits in 7 days: 89  
    Listed functions:
    GetAdaptersAddresses
    GlobalAlloc
    GlobalFree
    Printer friendly API declarations
    My comment:
    Dynamic Host Configuration Protocol (DHCP) FAQ

    Christian Ehlscheid offered this code on UniversalThread as a solution for obtaining physical address (MAC address) for a given ip address:

    ? IpToMacAddress("192.168.1.0")

    FUNCTION IpToMacAddress(lcIP)
            DECLARE INTEGER inet_addr IN ws2_32.dll STRING cIP
            DECLARE INTEGER SendARP IN iphlpapi.dll;
                    INTEGER destIP, INTEGER sourceIP,;
                    STRING @ pMacAddr, INTEGER @ PhyAddrLen
            LOCAL lnHr, lnIpAddr, lcMacAddr, lnLen
            lnIpAddr = inet_addr(lcIp)
            lcMacAddr = REPLICATE(CHR(0),6)
            lnLen = 6
            lnHr = SendARP(lnIpAddr,0,@lcMacAddr,@lnLen)
            RETURN BinaryToMac(lcMacAddr,lnLen)
    ENDFUNC

    FUNCTION BinaryToMac(lcMacAddr, lnLen)
            LOCAL lcMac, xj
            lcMac = ""
            FOR xj = 1 TO lnLen - 1
                    lcMac = lcMac + RIGHT(TRANSFORM(ASC(;
                            SUBSTR(lcMacAddr,xj,1)),"@0"),2) + ":"
            ENDFOR
            lcMac = lcMac + RIGHT(TRANSFORM(ASC(;
                    SUBSTR(lcMacAddr,lnLen,1)),"@0"),2)
            RETURN lcMac
    ENDFUNC


    The Address Resolution Protocol (ARP) is a protocol used by the Internet Protocol (IP) [RFC826], specifically IPv4, to map IP network addresses to the hardware addresses used by a data link protocol.
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