Ist Rechner erreichbar?

[fkerber]

paritycheck stellt hier eine Möglichkeit vor, wie man feststellen kann, ob ein Rechner erreichbar ist.

Delphi-Quellcode:

unit hostalive;

interface

uses
  Windows, Winsock; // Winapi.Windows, Winapi.Winsock;

function IsHostAlive(Hostname: String; pTripTime: PCardinal=nil; Timeout: Integer=1000; TTL: Integer=255): Boolean;

implementation

type
  IP_OPTION_INFORMATION = packed record
    TTL: Byte;
    TOS: Byte;
    Flags: Byte;
    OptionsSize: Byte;
    OptionsData: PAnsiChar;
  end;
  PIP_OPTION_INFORMATION = ^IP_OPTION_INFORMATION;

  ICMP_ECHO_REPLY = packed record
    Address: in_addr;
    Status: Cardinal;
    RoundTripTime: Cardinal;
    DataSize: Word;
    Reserved: Word;
    Data: Pointer;
    Options: IP_OPTION_INFORMATION;
  end;
  PICMP_ECHO_REPLY = ^ICMP_ECHO_REPLY;

function IcmpCreateFile: THandle; stdcall; external 'Iphlpapi.dll';
function IcmpCloseHandle(IcmpHandle: THandle): Boolean; stdcall; external 'Iphlpapi.dll';
function IcmpSendEcho(IcmpHandle: THandle; DestinationAddress: Cardinal; RequestData: Pointer; RequestSize: Word; RequestOptions: PIP_OPTION_INFORMATION; ReplyBuffer: Pointer; ReplySize: Cardinal; Timeout: Cardinal): Cardinal; stdcall; external 'Iphlpapi.dll';

function ResolveHost(Hostname: AnsiString): Cardinal;
var
  HostInfo: PHostEnt;
  T: ^PInAddr;
begin
  Result := inet_addr(PAnsiChar(Hostname));
  if Result = INADDR_NONE then begin
    HostInfo := gethostbyname(PAnsiChar(Hostname));
    if Assigned(HostInfo) then begin
      T := Pointer(HostInfo^.h_addr_list);
      if Assigned(T) and Assigned(T^) then
        Result := T^^.S_addr;
    end;
  end;
end;

function IsHostAlive(Hostname: String; pTripTime: PCardinal; Timeout, TTL: Integer): Boolean;
const
  SendBuffer: array[0..31] of AnsiChar = 'pingpongpingpongpingpongpingpong';
var
  WSA: TWSADATA;
  Reply: PICMP_ECHO_REPLY;
  Addr: Cardinal;
  hIcmp: THandle;
  Options: IP_OPTION_INFORMATION;
begin
  Result := False;
  FillChar(Options, SizeOf(IP_OPTION_INFORMATION), #0);
  Options.TTL := TTL;
  Options.TOS := 1;
  if WSAStartUp(((0 shl 8) + 2), WSA) = 0 then begin
    Addr := ResolveHost(AnsiString(Hostname));
    if Addr <> INADDR_NONE then begin
      hIcmp := IcmpCreateFile;
      if hicmp <> INVALID_HANDLE_VALUE then begin
        Reply := nil;
        try
          Reply := AllocMem(SizeOf(ICMP_ECHO_REPLY) + SizeOf(SendBuffer));
          IcmpSendEcho(hIcmp, Addr, @SendBuffer[0], SizeOf(SendBuffer), @Options, Reply, SizeOf(ICMP_ECHO_REPLY) + SizeOf(SendBuffer), Timeout);
          Result := Reply^.Status = 0;
          if Result and Assigned(pTripTime) then
            pTripTime^ := Reply^.RoundTripTime;
        finally
          IcmpCloseHandle(hIcmp);
          if Assigned(Reply) then
            FreeMem(Reply);
          WSACleanup;
        end;
      end;
    end else begin
      // Hostname konnte nicht aufgelöst werden.
      WSACleanup;
    end;
  end else begin
    // Winsock konnte nicht gestartet werden.
  end;
end;

end.

Beispielaufruf:

Delphi-Quellcode:

procedure TForm1.Button1Click(Sender: TObject);
var
  RTT:Cardinal;
begin
  if IsHostalive('google.de', @RTT) then
     showmessage(inttostr(RTT)+'ms');
end;