remote-curl: fall back to Basic auth if Negotiate fails

Apache servers using mod_auth_kerb can be configured to allow the user
to authenticate either using Negotiate (using the Kerberos ticket) or
Basic authentication (using the Kerberos password).  Often, one will
want to use Negotiate authentication if it is available, but fall back
to Basic authentication if the ticket is missing or expired.

However, libcurl will try very hard to use something other than Basic
auth, even over HTTPS.  If Basic and something else are offered, libcurl
will never attempt to use Basic, even if the other option fails.
Teach the HTTP client code to stop trying authentication mechanisms that
don't use a password (currently Negotiate) after the first failure,
since if they failed the first time, they will never succeed.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/http.c b/http.c
index 040f362a6a299618288c9249588ceb7aed6f3011..44b130c54adc6e0b966fd3423e13e6b72809cb0c 100644 (file)
--- a/http.c
+++ b/http.c
@@ -62,6 +62,9 @@ static const char *user_agent;
 
 static struct credential cert_auth = CREDENTIAL_INIT;
 static int ssl_cert_password_required;
+#ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
+static unsigned long http_auth_methods = CURLAUTH_ANY;
+#endif
 
 static struct curl_slist *pragma_header;
 static struct curl_slist *no_pragma_header;
@@ -580,6 +583,9 @@ struct active_request_slot *get_active_slot(void)
        curl_easy_setopt(slot->curl, CURLOPT_UPLOAD, 0);
        curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);
        curl_easy_setopt(slot->curl, CURLOPT_FAILONERROR, 1);
+#ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
+       curl_easy_setopt(slot->curl, CURLOPT_HTTPAUTH, http_auth_methods);
+#endif
        if (http_auth.password)
                init_curl_http_auth(slot->curl);
 
@@ -870,6 +876,9 @@ int handle_curl_result(struct slot_results *results)
                        credential_reject(&http_auth);
                        return HTTP_NOAUTH;
                } else {
+#ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
+                       http_auth_methods &= ~CURLAUTH_GSSNEGOTIATE;
+#endif
                        return HTTP_REAUTH;
                }
        } else {
@@ -986,6 +995,7 @@ static void extract_content_type(struct strbuf *raw, struct strbuf *type,
                strbuf_addstr(charset, "ISO-8859-1");
 }
 
+
 /* http_request() targets */
 #define HTTP_REQUEST_STRBUF    0
 #define HTTP_REQUEST_FILE      1