unit Ping;

interface
uses
  Windows, SysUtils, Classes;

type
  TSunB = packed record
    s_b1, s_b2, s_b3, s_b4: byte;
  end;

  TSunW = packed record
    s_w1, s_w2: word;
  end;

  PIPAddr = ^TIPAddr;
  TIPAddr = record
    case integer of
      0: (S_un_b: TSunB);
      1: (S_un_w: TSunW);
      2: (S_addr: longword);
  end;

  IPAddr = TIPAddr;


function IcmpCreateFile : THandle; stdcall; external 'icmp.dll';
function IcmpCloseHandle (icmpHandle : THandle) : boolean; stdcall; external 'icmp.dll';
function IcmpSendEcho (IcmpHandle : THandle; DestinationAddress : IPAddr;RequestData : Pointer; RequestSize : Smallint; RequestOptions : pointer; ReplyBuffer : Pointer; ReplySize : DWORD; Timeout : DWORD) : DWORD; stdcall; external 'icmp.dll';
function Ping(InetAddress : string) : boolean;

implementation

uses
  WinSock;


function Fetch(var AInput: string;
                      const ADelim: string = ' ';
                      const ADelete: Boolean = true)
 : string;
var
  iPos: Integer;
begin
  if ADelim = #0 then begin
    // AnsiPos does not work with #0
    iPos := Pos(ADelim, AInput);
  end else begin
    iPos := Pos(ADelim, AInput);
  end;
  if iPos = 0 then begin
    Result := AInput;
    if ADelete then begin
      AInput := '';
    end;
  end else begin
    result := Copy(AInput, 1, iPos - 1);
    if ADelete then begin
      Delete(AInput, 1, iPos + Length(ADelim) - 1);
    end;
  end;
end;

procedure TranslateStringToTInAddr(AIP: string; var AInAddr);
var
  phe: PHostEnt;
  pac: PChar;
  GInitData: TWSAData;
begin
  WSAStartup($101, GInitData);
  try
    phe := GetHostByName(PChar(AIP));
    if Assigned(phe) then
    begin
      pac := phe^.h_addr_list^;
      if Assigned(pac) then
      begin
        with TIPAddr(AInAddr).S_un_b do begin
          s_b1 := Byte(pac[0]);
          s_b2 := Byte(pac[1]);
          s_b3 := Byte(pac[2]);
          s_b4 := Byte(pac[3]);
        end;
      end
      else
      begin
        raise Exception.Create('Error getting IP from HostName');
      end;
    end
    else
    begin
      raise Exception.Create('Error getting HostName');
    end;
  except
    FillChar(AInAddr, SizeOf(AInAddr), #0);
  end;
  WSACleanup;
end;

function Ping(InetAddress : string) : boolean;
var
 Handle : THandle;
 InAddr : IPAddr;
 DW : DWORD;
 rep : array[1..128] of byte;
begin
  result := false;
  Handle := IcmpCreateFile;
  if Handle = INVALID_HANDLE_VALUE then
   Exit;
  TranslateStringToTInAddr(InetAddress, InAddr);
  DW := IcmpSendEcho(Handle, InAddr, nil, 0, nil, @rep, 128, 0);
  Result := (DW <> 0);
  IcmpCloseHandle(Handle);
end;

end.

