获得远程或本地机器的网卡的MAC

下面的函数以'XX-XX-XX-XX-XX-XX' 的格式返回远程或本地机器的MAC地址。

Function to return the MAC address of a remote or local machine in the format 'XX-XX-XX-XX-XX-XX'

返回的MAC地址是一个能用在多个方面的唯一标识。使用方法：
ShowMessage(GetMacAddress('//MHEYDON');
输出'00-02-08-E7-99-6B'

// ======================================================================
//返回值是主机AServerName的MAC地址
//AServerName参数的格式为'//ServerName' 或者 'ServerName'
//参数ServerName为空时返回本机的MAC地址
//MAC地址以'XX-XX-XX-XX-XX-XX'的格式返回
// ======================================================================

function GetMacAddress(const AServerName : string) : string;
type
     TNetTransportEnum = function(pszServer : PWideChar;
                                  Level : DWord;
                                  var pbBuffer : pointer;
                                  PRefMaxLen : LongInt;
                                  var EntriesRead : DWORD;
                                  var TotalEntries : DWORD;
                                  var ResumeHandle : DWORD) : DWORD; stdcall;

     TNetApiBufferFree = function(Buffer : pointer) : DWORD; stdcall;

     PTransportInfo = ^TTransportInfo;
     TTransportInfo = record
                       quality_of_service : DWORD;
                       number_of_vcs : DWORD;
                       transport_name : PWChar;
                       transport_address : PWChar;
                       wan_ish : boolean;
                     end;

var E,ResumeHandle,
    EntriesRead,
    TotalEntries : DWORD;
    FLibHandle : THandle;
    sMachineName,
    sMacAddr,
    Retvar : string;
    pBuffer : pointer;
    pInfo : PTransportInfo;
    FNetTransportEnum : TNetTransportEnum;
    FNetApiBufferFree : TNetApiBufferFree;
    pszServer : array[0..128] of WideChar;
    i,ii,iIdx : integer;
begin
  sMachineName := trim(AServerName);
  Retvar := '00-00-00-00-00-00';

  // Add leading // if missing
  if (sMachineName <> '') and (length(sMachineName) >= 2) then begin
    if copy(sMachineName,1,2) <> '//' then
      sMachineName := '//' + sMachineName
  end;

  // Setup and load from DLL
  pBuffer := nil;
  ResumeHandle := 0;
  FLibHandle := LoadLibrary('NETAPI32.DLL');

  // Execute the external function
  if FLibHandle <> 0 then begin
    @FNetTransportEnum := GetProcAddress(FLibHandle,'NetWkstaTransportEnum');
    @FNetApiBufferFree := GetProcAddress(FLibHandle,'NetApiBufferFree');
    E := FNetTransportEnum(StringToWideChar(sMachineName,pszServer,129),0,
                           pBuffer,-1,EntriesRead,TotalEntries,Resumehandle);

    if E = 0 then begin
      pInfo := pBuffer;

      // Enumerate all protocols - look for TCPip
      for i := 1 to EntriesRead do begin
        if pos('TCPIP',UpperCase(pInfo^.transport_name)) <> 0 then begin
          // Got It - now format result 'xx-xx-xx-xx-xx-xx'
          iIdx := 1;
          sMacAddr := pInfo^.transport_address;

          for ii := 1 to 12 do begin
            Retvar[iIdx] := sMacAddr[ii];
            inc(iIdx);
            if iIdx in [3,6,9,12,15] then inc(iIdx);
          end;
        end;

        inc(pInfo);
      end;
      if pBuffer <> nil then FNetApiBufferFree(pBuffer);
    end;

    try
      FreeLibrary(FLibHandle);
    except 
      // 错误处理
    end;
  end;
  result:=Retvar;
end;