Indy HTTP: reading response content on a 403

Question

I am having a problem using Indy HTTP (in Delphi) with the Google Contacts API.

Please refer to the section "ClientLogin Response" on the following page:

http://code.google.com/apis/accounts/docs/AuthForInstalledApps.html

The server returns a 403 when the authentication is incorrect or an error occurs... as expected. However, according to this document, there is information in the response content that is needed by the client, e.g. the error reason, and captcha URL, etc.

The problem is that the Indy IdHTTP component throws an exception on a 403 and the response content is empty. I have found no way so far to get to this content. I've tried wrapping the call to Post in a try...except then reading the response stream, but it always empty on a 403.

How would I go about doing this?

Answer 1

You are right. It seems in TIdHTTPProtocol.ProcessResponse the response is read but after that discarded. (And not even set to nil)

But it should be easy to adapt the CheckException function to write the response into IdHTTP.Response.ContentStream

Perhaps you could file a bug report or a feature request.

Answer 2

I've found a solution. Looks like the content is stored in the ErrorMessage field of EIdHTTPProtocolException.

try 
   http.Post('https://www.google.com/accounts/ClientLogin', slReq);
except
   on E: EIdHTTPProtocolException do
      Memo1.Lines.Add(E.ErrorMessage);
end;

seems to do the trick.

(By the way, I am using Indy 9. I am sure Indy 10 is similar.)