Merge commit from fork

Block authentication using alternate method.

Author: zdohnal

scheduler/auth.c

@@ -576,6 +576,16 @@ cupsdAuthorize(cupsd_client_t *con)	/* I - Client connection */
 
     int	userlen;			/* Username:password length */
 
+   /*
+    * Only allow Basic if enabled...
+    */
+
+    if (type != CUPSD_AUTH_BASIC)
+    {
+      cupsdLogClient(con, CUPSD_LOG_ERROR, "Basic authentication is not enabled.");
+      return;
+    }
+
     authorization += 5;
     while (isspace(*authorization & 255))
       authorization ++;
@@ -621,7 +631,6 @@ cupsdAuthorize(cupsd_client_t *con)	/* I - Client connection */
     * Validate the username and password...
     */
 
-    if (type == CUPSD_AUTH_BASIC)
     {
 #if HAVE_LIBPAM
      /*
@@ -715,6 +724,16 @@ cupsdAuthorize(cupsd_client_t *con)	/* I - Client connection */
 		*name,			// Real name
 		*email;			// Email address
 
+   /*
+    * Only allow OAuth if enabled...
+    */
+
+    if (type != CUPSD_AUTH_BEARER)
+    {
+      cupsdLogClient(con, CUPSD_LOG_ERROR, "OAuth authentication is not enabled.");
+      return;
+    }
+
     // Skip whitespace after "Bearer"...
     authorization += 7;
     while (isspace(*authorization & 255))
@@ -768,6 +787,16 @@ cupsdAuthorize(cupsd_client_t *con)	/* I - Client connection */
 					/* Output token for username */
     gss_name_t		client_name;	/* Client name */
 
+   /*
+    * Only allow Kerberos if enabled...
+    */
+
+    if (type != CUPSD_AUTH_NEGOTIATE)
+    {
+      cupsdLogClient(con, CUPSD_LOG_ERROR, "Kerberos authentication is not enabled.");
+      return;
+    }
+
 #  ifdef __APPLE__DISABLED // Remove DISABLED if ever this code is used for macOS installer
    /*
     * If the weak-linked GSSAPI/Kerberos library is not present, don't try