Delphi - File size by URL - error 12150 - delphi

Question

Delphi 6 Prof, Win7 OS.
I have this code to get the file size by URL:
function TDDWIToolObject.GetFileSize(out Size: Int64): boolean;
var
hInet: HINTERNET;
hRequest : HINTERNET;
lpdwBufferLength: DWORD;
lpdwReserved : DWORD;
ServerName: string;
Resource: string;
FileSizeBuffer : array[0..32] of char;
//SizeCard : Cardinal;
begin
ParseURL(Url, ServerName, Resource);
Result := False;
Size := 0;
hInet := InternetOpen(PChar(_UserAgent), INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if hInet=nil then begin
FErrorCode := GetLastError;
Exit;
end;
try
hRequest := InternetOpenUrl(hInet, PChar(URL), PCHar(Headers), Length(HEaders), 0, 0);
try
FillChar(FileSizeBuffer, SizeOf(FileSizeBuffer), #0);
lpdwBufferLength := SizeOf(FileSizeBuffer);
lpdwReserved :=0;
if not HttpQueryInfo(
hRequest,
HTTP_QUERY_CONTENT_LENGTH,
#FileSizeBuffer, lpdwBufferLength, lpdwReserved) then begin
FErrorCode:=GetLastError;
Exit;
end;
Size := StrToInt64(StrPas(FileSizeBuffer));
Result := True;
finally
InternetCloseHandle(hRequest);
end;
finally
InternetCloseHandle(hInet);
end;
end;
It is working good with my machine + DSL connection.
But when I check this code in other place which is fully protected (proxy + many policies) then I get error code 12150... :-(
What is interesting, that I can download this file, when I use this code:
function TDDWIToolObject.DownloadFile;
var
hInet: HINTERNET;
hFile: HINTERNET;
pbuffer: Pointer;
bytesRead: DWORD;
Stm : TFileStream;
TotalBytes : Int64;
AbortIt : boolean;
begin
Result := False;
FErrorCode := -1;
FAborted := False;
hInet := InternetOpen(PChar(_UserAgent), INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if hInet = nil
then begin
FErrorCode := GetLastError;
Exit;
end;
try
hFile := InternetOpenURL(hInet, PChar(URL), PChar(FHeaders), Length(FHeaders), 0, 0);
if hFile = nil
then begin
FErrorCode := GetLastError;
Exit;
end;
try
Stm := TFileStream.Create(FN, fmCreate);
try
GetMem(pbuffer, FBufferSize);
try
TotalBytes := 0; AbortIt := False;
while (not FAborted) do begin
if not InternetReadFile(hFile, pbuffer, FBufferSize, bytesRead) then begin
FErrorCode := GetLastError;
Exit;
end;
if bytesRead > 0 then begin
Stm.WriteBuffer(pbuffer^, bytesRead);
if Assigned(FOnBytesArrived)
then begin
inc(TotalBytes, bytesRead);
FOnBytesArrived(Self, TotalBytes, AbortIt);
if AbortIt
then Abort;
end;
end else begin
break;
end;
end;
finally
FreeMem(pbuffer);
end;
if not FAborted
then Result := True;
finally
Stm.Free;
end;
finally
InternetCloseHandle(hFile);
end;
finally
InternetCloseHandle(hInet);
end;
end;
It is interesting because sysadmin allowed the requests to this URL in proxy, and the downloads work for me - only the content length requests fail.
I want to ask one question, but it is hard to do, because many of them is in my mind...
Do you have some idea what we can do to allow the requests?
Maybe HttpRequest uses another port, or some "illegal" what isn't proxiable?
Or my code is seems to be wrong? Why it is working in nonprotected area? What are the differents between download and get content length requests?
So the question is as in summarized format: do you have some idea what can I do to I get the file size before downloading?
Thanks for it.

Answer 1

This error can be caused by many factors (ERROR_HTTP_HEADER_NOT_FOUND), in your code you are not checking the result of the InternetOpenUrl function before to call the HttpQueryInfo method, and I don't see the content of the _UserAgent and Headers variables to give you a more exact answer. Anyway try using the HttpOpenRequest and HttpSendRequest functions instead of InternetOpenURL.
Try this sample
uses
Windows,
SysUtils,
WinInet;
const
sUserAgent = 'Mozilla/5.001 (windows; U; NT4.0; en-US; rv:1.0) Gecko/25250101';
function GetWinInetError(ErrorCode:Cardinal): string;
const
winetdll = 'wininet.dll';
var
Len: Integer;
Buffer: PChar;
begin
Len := FormatMessage(
FORMAT_MESSAGE_FROM_HMODULE or FORMAT_MESSAGE_FROM_SYSTEM or
FORMAT_MESSAGE_ALLOCATE_BUFFER or FORMAT_MESSAGE_IGNORE_INSERTS or FORMAT_MESSAGE_ARGUMENT_ARRAY,
Pointer(GetModuleHandle(winetdll)), ErrorCode, 0, #Buffer, SizeOf(Buffer), nil);
try
while (Len > 0) and {$IFDEF UNICODE}(CharInSet(Buffer[Len - 1], [#0..#32, '.'])) {$ELSE}(Buffer[Len - 1] in [#0..#32, '.']) {$ENDIF} do Dec(Len);
SetString(Result, Buffer, Len);
finally
LocalFree(HLOCAL(Buffer));
end;
end;
procedure ParseURL(const lpszUrl: string; var Host, Resource: string);
var
lpszScheme : array[0..INTERNET_MAX_SCHEME_LENGTH - 1] of Char;
lpszHostName : array[0..INTERNET_MAX_HOST_NAME_LENGTH - 1] of Char;
lpszUserName : array[0..INTERNET_MAX_USER_NAME_LENGTH - 1] of Char;
lpszPassword : array[0..INTERNET_MAX_PASSWORD_LENGTH - 1] of Char;
lpszUrlPath : array[0..INTERNET_MAX_PATH_LENGTH - 1] of Char;
lpszExtraInfo : array[0..1024 - 1] of Char;
lpUrlComponents : TURLComponents;
begin
ZeroMemory(#lpszScheme, SizeOf(lpszScheme));
ZeroMemory(#lpszHostName, SizeOf(lpszHostName));
ZeroMemory(#lpszUserName, SizeOf(lpszUserName));
ZeroMemory(#lpszPassword, SizeOf(lpszPassword));
ZeroMemory(#lpszUrlPath, SizeOf(lpszUrlPath));
ZeroMemory(#lpszExtraInfo, SizeOf(lpszExtraInfo));
ZeroMemory(#lpUrlComponents, SizeOf(TURLComponents));
lpUrlComponents.dwStructSize := SizeOf(TURLComponents);
lpUrlComponents.lpszScheme := lpszScheme;
lpUrlComponents.dwSchemeLength := SizeOf(lpszScheme);
lpUrlComponents.lpszHostName := lpszHostName;
lpUrlComponents.dwHostNameLength := SizeOf(lpszHostName);
lpUrlComponents.lpszUserName := lpszUserName;
lpUrlComponents.dwUserNameLength := SizeOf(lpszUserName);
lpUrlComponents.lpszPassword := lpszPassword;
lpUrlComponents.dwPasswordLength := SizeOf(lpszPassword);
lpUrlComponents.lpszUrlPath := lpszUrlPath;
lpUrlComponents.dwUrlPathLength := SizeOf(lpszUrlPath);
lpUrlComponents.lpszExtraInfo := lpszExtraInfo;
lpUrlComponents.dwExtraInfoLength := SizeOf(lpszExtraInfo);
InternetCrackUrl(PChar(lpszUrl), Length(lpszUrl), ICU_DECODE or ICU_ESCAPE, lpUrlComponents);
Host := lpszHostName;
Resource := lpszUrlPath;
end;
function GetRemoteFileSize(const Url : string): Integer;
var
hInet : HINTERNET;
hConnect : HINTERNET;
hRequest : HINTERNET;
lpdwBufferLength: DWORD;
lpdwReserved : DWORD;
ServerName: string;
Resource: string;
ErrorCode : Cardinal;
begin
ParseURL(Url,ServerName,Resource);
Result:=0;
hInet := InternetOpen(PChar(sUserAgent), INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if hInet=nil then
begin
ErrorCode:=GetLastError;
raise Exception.Create(Format('InternetOpen Error %d Description %s',[ErrorCode,GetWinInetError(ErrorCode)]));
end;
try
hConnect := InternetConnect(hInet, PChar(ServerName), INTERNET_DEFAULT_HTTP_PORT, nil, nil, INTERNET_SERVICE_HTTP, 0, 0);
if hConnect=nil then
begin
ErrorCode:=GetLastError;
raise Exception.Create(Format('InternetConnect Error %d Description %s',[ErrorCode,GetWinInetError(ErrorCode)]));
end;
try
hRequest := HttpOpenRequest(hConnect, PChar('HEAD'), PChar(Resource), nil, nil, nil, 0, 0);
if hRequest<>nil then
begin
try
lpdwBufferLength:=SizeOf(Result);
lpdwReserved :=0;
if not HttpSendRequest(hRequest, nil, 0, nil, 0) then
begin
ErrorCode:=GetLastError;
raise Exception.Create(Format('HttpOpenRequest Error %d Description %s',[ErrorCode,GetWinInetError(ErrorCode)]));
end;
if not HttpQueryInfo(hRequest, HTTP_QUERY_CONTENT_LENGTH or HTTP_QUERY_FLAG_NUMBER, #Result, lpdwBufferLength, lpdwReserved) then
begin
Result:=0;
ErrorCode:=GetLastError;
raise Exception.Create(Format('HttpQueryInfo Error %d Description %s',[ErrorCode,GetWinInetError(ErrorCode)]));
end;
finally
InternetCloseHandle(hRequest);
end;
end
else
begin
ErrorCode:=GetLastError;
raise Exception.Create(Format('HttpOpenRequest Error %d Description %s',[ErrorCode,GetWinInetError(ErrorCode)]));
end;
finally
InternetCloseHandle(hConnect);
end;
finally
InternetCloseHandle(hInet);
end;
end;