Thread (12 messages) flat view 12 messages, 4 authors, 2017-02-25

Re: [PATCH 2/2] http: add an "auto" mode for http.emptyauth

From: Jeff King <hidden>
Date: 2017-02-25 19:22:19
Subsystem: the rest · Maintainer: Linus Torvalds

On Sat, Feb 25, 2017 at 12:48:54PM +0100, Johannes Schindelin wrote:
Hi,

On Wed, 22 Feb 2017, Jeff King wrote:
quoted
[two beautiful patches]
I applied them and verified that the reported issue is fixed. Thank you!

Hopefully you do not mind that I cherry-picked them in preparation for
Git for Windows v2.12.0?
No, I don't mind. I'm happy that more people with a non-Basic setup are
verifying that they work. :)

Of the changes:
quoted hunk ↗ jump to hunk
diff --git a/http.c b/http.c
index f8eb0f23d6c..fb94c444c80 100644
--- a/http.c
+++ b/http.c
@@ -334,7 +334,10 @@ static int http_options(const char *var, const char *value, void *cb)
 		return git_config_string(&user_agent, var, value);
 
 	if (!strcmp("http.emptyauth", var)) {
-		curl_empty_auth = git_config_bool(var, value);
+		if (value && !strcmp("auto", value))
+			curl_empty_auth = -1;
+		else
+			curl_empty_auth = git_config_bool(var, value);
 		return 0;
 	}
Obviously good, I should have included this in the original.
+#ifndef LIBCURL_CAN_HANDLE_AUTH_ANY
+	/*
+	 * Our libcurl is too old to do AUTH_ANY in the first place;
+	 * just default to turning the feature off.
+	 */
 #else
-		/*
-		 * Our libcurl is too old to do AUTH_ANY in the first place;
-		 * just default to turning the feature off.
-		 */
The ifdef reordering here is good.
+	/*
+	 * In the automatic case, kick in the empty-auth
+	 * hack as long as we would potentially try some
+	 * method more exotic than "Basic".
+	 *
+	 * But only do this when this is our second or
+	 * subsequent * request, as by then we know what
+	 * methods are available.
+	 */
+	if (http_auth_methods_restricted)
+		switch (http_auth_methods) {
+		case CURLAUTH_BASIC:
+		case CURLAUTH_DIGEST:
+#ifdef CURLAUTH_DIGEST_IE
+		case CURLAUTH_DIGEST_IE:
 #endif
[...]
+			return 0;
+		default:
+			return 1;
+		}
This is an improvement over my basic-only, but I think you actually want
to bitmask here. A server which advertises only BASIC|DIGEST should not
do empty-auth, but wouldn't match your switch statement.

Patch below.
Now, how to get this into upstream Git, too? Jeff, do you want to submit a
v2? In that case, would you please consider the fixup! I mentioned above?
Otherwise I'd be happy to take it from here.
I don't mind doing a v2. I'm unsure of whether we want to default to
"auto" or not upstream. It seems from your releases that you think it is
safe enough to do in Windows. And I guess nobody outside of that is
really doing NTLM. So it's OK, I guess?

<shrug> I don't have enough information to make an intelligent opinion,
so I'm happy to defer.

I'll send my v2 in a minute. Here's the interdiff/fixup if you need to
apply it separately:
diff --git a/http.c b/http.c
index 523c43cf9..dd637d031 100644
--- a/http.c
+++ b/http.c
@@ -126,6 +126,13 @@ static int ssl_cert_password_required;
 #ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
 static unsigned long http_auth_methods = CURLAUTH_ANY;
 static int http_auth_methods_restricted;
+/* Modes for which empty_auth cannot actually help us. */
+static unsigned long empty_auth_useless =
+	CURLAUTH_BASIC
+#ifdef CURLAUTH_DIGEST_IE
+	| CURLAUTH_DIGEST_IE
+#endif
+	| CURLAUTH_DIGEST;
 #endif
 
 static struct curl_slist *pragma_header;
@@ -400,23 +407,15 @@ static int curl_empty_auth_enabled(void)
 	/*
 	 * In the automatic case, kick in the empty-auth
 	 * hack as long as we would potentially try some
-	 * method more exotic than "Basic".
+	 * method more exotic than "Basic" or "Digest".
 	 *
 	 * But only do this when this is our second or
 	 * subsequent * request, as by then we know what
 	 * methods are available.
 	 */
-	if (http_auth_methods_restricted)
-		switch (http_auth_methods) {
-		case CURLAUTH_BASIC:
-		case CURLAUTH_DIGEST:
-#ifdef CURLAUTH_DIGEST_IE
-		case CURLAUTH_DIGEST_IE:
-#endif
-			return 0;
-		default:
-			return 1;
-		}
+	if (http_auth_methods_restricted &&
+	    (http_auth_methods & ~empty_auth_useless))
+		return 1;
 #endif
 	return 0;
 }
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