function GetProxyInformation: string;
var
ProxyInfo: PInternetProxyInfo;
Len: LongWord;
begin
Result := '';
Len := 4096;
GetMem(ProxyInfo, Len);
try
 if InternetQueryOption(nil, INTERNET_OPTION_PROXY, ProxyInfo, Len) then
  if ProxyInfo^.dwAccessType = INTERNET_OPEN_TYPE_PROXY then
  begin
   Result := ProxyInfo^.lpszProxy
  end;
finally
 FreeMem(ProxyInfo);
end;
end;

{**************************************************************************
* NAME:    GetProxyServer
* DESC:    Proxy-Server Einstellungen abfragen
* PARAMS:  protocol => z.B. 'http' oder 'ftp'
* RESULT:  [-]
* CREATED: 08-04-2004/shmia
*************************************************************************}

procedure GetProxyServer(protocol: string; var ProxyServer: string; var ProxyPort: Integer);
var
i: Integer;
proxyinfo: string;
begin
ProxyServer := '';
ProxyPort := 0;

proxyinfo := GetProxyInformation;
if proxyinfo = '' then
 Exit;

protocol := protocol + '=';

i := Pos(protocol, proxyinfo);
if i > 0 then
begin
 Delete(proxyinfo, 1, i + Length(protocol));
 i := Pos(';', ProxyServer);
 if i > 0 then
  proxyinfo := Copy(proxyinfo, 1, i - 1);
end;

i := Pos(':', proxyinfo);
if i > 0 then
begin
 ProxyPort := StrToIntDef(Copy(proxyinfo, i + 1, Length(proxyinfo) - i), 0);
 ProxyServer := Copy(proxyinfo, 1, i - 1)
end
end;

type
 LPVOID = Pointer;

 pWinHttpAutoProxyOptions = ^WINHTTP_AUTOPROXY_OPTIONS;
 WINHTTP_AUTOPROXY_OPTIONS = record
    dwFlags: DWORD;
    dwAutoDetectFlags: DWORD;
    lpszAutoConfigUrl: LPCWSTR;
    lpvReserved: LPVOID;
    dwReserved: DWORD;
    fAutoLogonIfChallenged: BOOL;
 end;

 TWinHttpOpen = function(pwszUserAgent: LPCWSTR; dwAccessType: DWORD; pwszProxyName: LPCWSTR; pwszProxyBypass: LPCWSTR; dwFlags: DWORD): HINTERNET; stdcall;
 TWinHttpCloseHandle = function(hInternet: HINTERNET): BOOL; stdcall;
 TWinHttpGetProxyForUrl = function(hSession: HINTERNET; lpcwszUrl: LPCWSTR; pAutoProxyOptions: pWinHttpAutoProxyOptions; out pProxyInfo: PInternetProxyInfo): BOOL; stdcall;

const

 WINHTTP_ACCESS_TYPE_NO_PROXY    = 1;

 WINHTTP_AUTOPROXY_AUTO_DETECT    = $00000001;
 WINHTTP_AUTOPROXY_CONFIG_URL    = $00000002;
 WINHTTP_AUTO_DETECT_TYPE_DHCP    = $00000001;
 WINHTTP_AUTO_DETECT_TYPE_DNS_A    = $00000002;

 TEST_PAGE_URL = 'http://www.google.com/';
 userAgent = 'Mozilla/4.0 (compatible; MSIE 6.0;Windows NT 5.1; SV1)';
var
 WinHttpDLL: THandle;

 WinHttpGetProxyForUrl: TWinHttpGetProxyForUrl;
 WinHttpOpen: TWinHttpOpen;
 WinHttpCloseHandle: TWinHttpCloseHandle;

 hSession: HINTERNET;
 ProxyInfo: PInternetProxyInfo;
 pAutoProxyOptions: pWinHttpAutoProxyOptions;

begin

 WinHttpDLL := LoadLibrary(PChar('WinHttp.dll'));
 try

 @WinHttpOpen   := GetProcAddress(WinHttpDLL, 'WinHttpOpen');
 @WinHttpCloseHandle   := GetProcAddress(WinHttpDLL, 'WinHttpCloseHandle');
 @WinHttpGetProxyForUrl := GetProcAddress(WinHttpDLL, WinHttpGetProxyForUrl');

     hSession := WinHttpOpen(userAgent, WINHTTP_ACCESS_TYPE_NO_PROXY, nil, nil, 0);

     New(ProxyInfo);
     New(pAutoProxyOptions);

      pAutoProxyOptions^.dwFlags := WINHTTP_AUTOPROXY_CONFIG_URL;
      pAutoProxyOptions^.dwAutoDetectFlags := 0;
      pAutoProxyOptions^.lpszAutoConfigUrl := TEST_PAGE_URL;
      pAutoProxyOptions^.lpvReserved := nil;
      pAutoProxyOptions^.dwReserved := 0;
      pAutoProxyOptions^.fAutoLogonIfChallenged := True;

      if  WinHttpGetProxyForUrl(hSession,
                                TEST_PAGE_URL,
                                pAutoProxyOptions,
                                ProxyInfo)
       then  ShowMessage('TRUE')
      else   ShowMessage('FALSE');

       ShowMessage(IntToStr(GetLastError));

    WinHttpCloseHandle(hSession);

    Dispose(pAutoProxyOptions);
    Dispose(ProxyInfo);

 finally
   FreeLibrary(WinHttpDLL);
 end;