Allow restriction of module command arguments

The module commands now support an optional flag for arguments that when
enabled checks that the argument module name matches the registered domain
name. This can be used to enforce argument type validity for arguments
that are given to modules that expect objects of a certain type.

For example, this is used by the cache and dbfwfilter to prevent valid
filters but of the wrong type being given as arguments.

include/maxscale/modulecmd.h

@@ -43,7 +43,7 @@ MXS_BEGIN_DECLS
  */
 typedef struct
 {
-    uint64_t    type;  /**< The argument type */
+    uint64_t    type;        /**< The argument type and options */
     const char *description; /**< The argument description */
 } modulecmd_arg_type_t;
 
@@ -68,13 +68,15 @@ typedef struct
 /**
  * Options for arguments, bits 9 through 32
  */
-#define MODULECMD_ARG_OPTIONAL (1 << 8) /**< The argument is optional */
+#define MODULECMD_ARG_OPTIONAL            (1 << 8) /**< The argument is optional */
+#define MODULECMD_ARG_NAME_MATCHES_DOMAIN (1 << 9) /**< Argument module name must match domain name */
 
 /**
  * Helper macros
  */
 #define MODULECMD_GET_TYPE(t) ((t)->type & 0xff)
 #define MODULECMD_ARG_IS_REQUIRED(t) (((t)->type & MODULECMD_ARG_OPTIONAL) == 0)
+#define MODULECMD_ALLOW_NAME_MISMATCH(t) (((t)->type & MODULECMD_ARG_NAME_MATCHES_DOMAIN) == 0)
 #define MODULECMD_ARG_PRESENT(t) (MODULECMD_GET_TYPE(t) != MODULECMD_ARG_NONE)
 
 /** Argument list node */