HTTP Auth: Add CURLAUTH_ONLY

This is a meta symbol. OR this value together with a single specific
auth value to force libcurl to probe for un-restricted auth and if not,
only that single auth algorithm is acceptable.

For example you can use CURLAUTH_DIGEST|CURLAUTH_ONLY to make libcurl
first probe for what method to use, but yet only consider Digest to be
acceptable.

Using _only_ CURLAUTH_DIGEST without the CURLAUTH_ONLY field, will make
libcurl explicitly use Digest right away and not do any probing.

1 files changed, 3 insertions, 0 deletions

diff --git a/include/curl/curl.h b/include/curl/curl.h
index e95887fe7..fbd0d9b01 100644
--- a/include/curl/curl.h
+++ b/include/curl/curl.h
@@ -585,6 +585,9 @@ typedef enum {
 #define CURLAUTH_GSSNEGOTIATE (1<<2)  /* GSS-Negotiate */
 #define CURLAUTH_NTLM         (1<<3)  /* NTLM */
 #define CURLAUTH_DIGEST_IE    (1<<4)  /* Digest with IE flavour */
+#define CURLAUTH_ONLY         (1<<31) /* used together with a single other
+                                         type to force no auth or just that
+                                         single type */
 #define CURLAUTH_ANY (~CURLAUTH_DIGEST_IE)  /* all fine types set */
 #define CURLAUTH_ANYSAFE (~(CURLAUTH_BASIC|CURLAUTH_DIGEST_IE))