Реализация передачи по сети сообщений

function
 NetSend(dest, Source, Msg: string
): Longint; overload;
 type

   TNetMessageBufferSendFunction = function
(servername, msgname, fromname: PWideChar;
     buf: PWideChar; buflen: Cardinal): Longint;
    stdcall
;
 var

   NetMessageBufferSend: TNetMessageBufferSendFunction;
   SourceWideChar: PWideChar;
   DestWideChar: PWideChar;
   MessagetextWideChar: PWideChar;
   Handle: THandle;
 begin

   Handle := LoadLibrary('NETAPI32.DLL');
   if
 Handle = 0 then

   begin

     Result := GetLastError;
     Exit;
   end
;
     @NetMessageBufferSend := GetProcAddress(Handle, 'NetMessageBufferSend');
   if
 @NetMessageBufferSend = nil
 then

   begin

     Result := GetLastError;
     Exit;
   end
;

   MessagetextWideChar := nil
;
   SourceWideChar      := nil
;
   DestWideChar        := nil
;

   try

     GetMem(MessagetextWideChar, Length(Msg) * SizeOf(WideChar) + 1);
     GetMem(DestWideChar, 20 * SizeOf(WideChar) + 1);
     StringToWideChar(Msg, MessagetextWideChar, Length(Msg) * SizeOf(WideChar) + 1);
     StringToWideChar(Dest, DestWideChar, 20 * SizeOf(WideChar) + 1);

     if
 Source = '' then

       Result := NetMessageBufferSend(nil
, DestWideChar, nil
,
         MessagetextWideChar, Length(Msg) * SizeOf(WideChar) + 1)
     else

     begin

       GetMem(SourceWideChar, 20 * SizeOf(WideChar) + 1);
       StringToWideChar(Source, SourceWideChar, 20 * SizeOf(WideChar) + 1);
       Result := NetMessageBufferSend(nil
, DestWideChar, SourceWideChar,
         MessagetextWideChar, Length(Msg) * SizeOf(WideChar) + 1);
       FreeMem(SourceWideChar);
     end
;
   finally

     FreeMem(MessagetextWideChar);
     FreeLibrary(Handle);
   end
;
 end
;

 function
 NetSend(Dest, Msg: string
): Longint; overload;
 begin

   Result := NetSend(Dest, '', Msg);
 end
;

 function
 NetSend(Msg: string
): Longint; overload;
 begin

   Result := NetSend('', '', Msg);
 end
;

 // Example: 

procedure
 TForm1.Button1Click(Sender: TObject);
 const

   NERR_BASE = 2100;
   NERR_NameNotFound = NERR_BASE + 173;
   NERR_NetworkError = NERR_BASE + 36;
   NERR_Success = 0;
 var

   Res: Longint;
   sMsg: string
;
 begin

   Res := NetSend('LoginName', 'Your Message...');
   case
 Res of

     ERROR_ACCESS_DENIED: sMsg := 'user does not have access to the requested information.';
     ERROR_INVALID_PARAMETER: sMsg := 'The specified parameter is invalid.';
     ERROR_NOT_SUPPORTED: sMsg := 'This network request is not supported.';
     NERR_NameNotFound: sMsg := 'The user name could not be found.';
     NERR_NetworkError: sMsg := 'A general failure occurred in the network hardware.';
     NERR_Success: sMsg := 'Message sent!';
   end
;
   ShowMessage(sMsg);
 end
;

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