Question

I am trying to intercept GET/POST that i get from IdHTTPProxyServer and send it to IdHTTP so i can replicate the GET/POST and eventually get cookies so I can login in to any website.

How can this be improved? If i try to execute this code it crashes.

procedure TForm1.IdHTTPProxyServer1HTTPDocument(
  AContext: TIdHTTPProxyServerContext; var VStream: TStream);
begin

if AContext.Command='POST' then begin
EmbeddedWB1.LoadFromString(IdHTTP1.Post(AContext.Target,AContext.Headers.Text)); << CRASH
end;

if AContext.Command='GET' then begin
EmbeddedWB1.LoadFromString(IdHTTP1.Get(AContext.Target)); << CRASH
end;

end; 

Answer 1

When using the OnHTTPDocument event, you need to look at the TIdHTTPProxyServerContext.TransferSource property to know if the event is being triggered for a client request that contains body data, or is being triggered for the target server’s response to the client request. Sending your own GET/POST request only makes sense when processing client requests, however the OnHTTPDocument event is not likely to ever be triggered for a GET request since there is no body data to capture.

You don’t need to use TIdHTTP in order to get the server’s cookies. Let TIdHTTPProxyServer do its work normally, and then you can extract the cookies from the TIdHTTPProxyServerContext.Headers property in the OnHTTPResponse event, eg:

procedure TForm1.IdHTTPProxyServer1HTTPResponse(AContext: TIdHTTPProxyServerContext);
var
  Cookies: TStringList;
begin
  Cookies := TStringList.Create;
  try
    AContext.Headers.Extract('Set-Cookie', Cookies);
    // use Cookies as needed, such as:
    // URI := TIdURI.Create(AContext.Target);
    // try
    //   CookieManager1.AddServerCookies(Cookies, URI);
    // finally
    //   URI.Free;
    // end;
  finally
    Cookies.Free;
  end;
end;