Re: [PATCH] http(s): automatically try NTLM authentication first

[Jeff King <peff@peff.net>]

On Wed, Feb 22, 2017 at 01:16:33PM -0800, Junio C Hamano wrote:

> David Turner <David.Turner@twosigma.com> writes:
> 
> > Always, no.  For failed authentication (or authorization), apparently, yes.  
> > I tested this by  setting the variable to false and then true, and trying to 
> > Push to a github repository which I didn't have write access to, with 
> > both an empty username (https://@:github.com/...) and no username 
> > (http://github.com/...).   I ran this under GIT_CURL_VERBOSE=1 and
> > I saw two 401 responses in the "http.emptyauth=true" case and one
> > in the false case.  I also tried with a repo that I did have access to (first
> > configuring the necessary tokens for HTTPS push access), and saw two
> > 401 responses in *both* cases.  
> 
> Thanks; that matches my observation.  I do not think we care about
> an extra roundtrip for the failure case, but as long as we do not
> increase the number of roundtrip in the normal case, we can declare
> that this is an improvement.  I am not quite sure where that extra
> 401 comes from in the normal case, and that might be an indication
> that we already are doing something wrong, though.

This patch drops the useless probe request:

diff --git a/http.c b/http.c
index 943e630ea..7b4c2db86 100644
--- a/http.c
+++ b/http.c
@@ -1663,6 +1663,9 @@ static int http_request(const char *url,
 		curlinfo_strbuf(slot->curl, CURLINFO_EFFECTIVE_URL,
 				options->effective_url);
 
+	if (results.auth_avail == CURLAUTH_BASIC)
+		http_auth_methods = CURLAUTH_BASIC;
+
 	curl_slist_free_all(headers);
 	strbuf_release(&buf);
 

but setting http.emptyauth adds back in the useless request. I think
that could be fixed by skipping the empty-auth thing when
http_auth_methods does not have CURLAUTH_NEGOTIATE in it (or perhaps
other methods need it to, so maybe skip it if _just_ BASIC is set).

I suspect the patch above could probably be generalized as:

  /* cut out methods we know the server doesn't support */
  http_auth_methods &= results.auth_avail;

and let curl figure it out from there.

-Peff