Delphi从Web获得具有表单授权的文件

Question

I need download file from Web with authorization. I use Delphi and Indy components. When the method Get performs the download, I get error "HTTP/1.0 404 Not Found". That seems to say that the authorization is failed, but file Response.html contains Web page, similar to the one that appears after login …

PS Prams for authorization form I took using Firefox Web development tools.

function TForm1.Login: string;
var
    Request: TStringList;
begin
    Result := '';
    try
        Request := TStringList.Create;
        try
            Request.Add('backurl=%2Fnewupgrade%2Findex.php');
            Request.Add('AUTH_FORM=Y');
            Request.Add('TYPE=AUTH');
            Request.Add('USER_LOGIN=xxxx');
            Request.Add('USER_PASSWORD=XXXX');
            IdHTTP1.AllowCookies := True;
            IdHTTP1.HandleRedirects := True;
            IdHTTP1.Request.ContentType := 'application/x-www-form-urlencoded';
            IdHTTP1.Request.Connection := 'keep-alive';
            Result := IdHTTP1.Post('http://www.uniko.ru/newupgrade/index.php?login=yes', Request);
        finally
            Request.Free;
        end;
    except
        on E: Exception do ShowMessage(E.Message);
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
    Response: string;
    fs: TStreamWriter;
    MS: TMemoryStream;
begin
    Response := Login;
    fs := TStreamWriter.Create('C:\Response.html');
    fs.Write(Response);
    fs.Free;

    // Download file
    MS := TMemoryStream.Create;
    try
        IdHTTP1.Request.ContentType := 'application/force-download; name="Setup.EXE"';
        IdHTTP1.Get('http://www.uniko.ru/newupgrade/izyat/Setup.EXE', MS);
        MS.SaveToFile('C:\Setup.tmp');
    finally
        MS.Free;
    end
end;

Answer 1

HTTP response code 404 means the requested URL was not found. You are thinking of 401, which is the server's request for authentication. TIdHTTP handles 401 internally, but depending on what kind of authentication it is asking for (Basic, NTLM, SSPI, etc), you may need to add various IdAuthentication... units to your uses clause to enable Indy's support for them.

The only way your code would write to Response.html is if the Post() reported HTTP response code 200 instead of 401, but is sent back the login page. The site is using webform authentication, not HTTP authentication. When posting a TStrings for webform authentication, do not url-encode the contents. Post() handles that internally for you. Specifically, this line:

Request.Add('backurl=%2Fnewupgrade%2Findex.php');

Should be this instead:

Request.Add('backurl=/newupgrade/index.php');

That may be causing the webform to fail, and might account for the 404. Look at the HTML being sent back, it might contain an error message in it.

Answer 2

I find solution!!!

I read this article: http://www.programmersclub.ru/%D0%90%D0%B2%D1%82%D0%BE%D1%80%D0%B8%D0%B7%D0%B0%D1%86%D0%B8%D1%8F-%D0%BD%D0%B0-mail-ru-%D1%81-%D0%BF%D0%BE%D0%BC%D0%BE%D1%89%D1%8C%D1%8E-indy/

and decide add Cooke parameter to HTTP1.Response.RawHeaders:

procedure TForm1.Button1Click(Sender: TObject);
var
  header, cookie: string;
  MS: TMemoryStream;
  p, p2: Integer;
begin
  Login;

  cookie := '';
  header := IdHTTP1.Response.RawHeaders.Text;
  while true  do begin
    p := pos('Cookie:', header);
    if p=0 then break;
    p := p+length('Cookie:')+1;
    p2 := pos(#$D#$A, copy(header, p, length(header)));
    if p2=0 then p2 := length(header);
    cookie := cookie + copy(header, p, p2-1)+';';
    header := copy(header, p+p2+1, length(header))
  end;

  if cookie<>'' then begin
    cookie := StringReplace(cookie, 'path=/;', '', [rfReplaceAll]);
    cookie := copy(cookie, 1, length(cookie)-1);
    IdHTTP1.Request.CustomHeaders.Add('Cookie: ' + cookie);
  end;

  // Download file
  MS := TMemoryStream.Create;
  try
    IdHTTP1.Request.ContentType := 'application/force-download; name="Setup.EXE"';
    IdHTTP1.Get('http://www.uniko.ru/newupgrade/izyat/Setup.EXE', MS);
    MS.SaveToFile('C:\Setup.tmp');
  finally
    MS.Free;
  end
end;

And its work!