Add fr_dict_attr_add_by_name(). Addresses #1883

This function adds an attribute ONLY by name, and not by number.
It can be used to add Attr-26, without polluting Vendor-Specific
for everyone else.

The dictionary code assumes that when two attributes are defined
for the same number, that the second one takes precedence over
the first one.  See "dictionary.compat" for examples

src/lib/dict.c

@@ -683,7 +683,7 @@ static fr_dict_attr_t *fr_dict_attr_alloc(TALLOC_CTX *ctx,
 	return da;
 }
 
-/** Add an attribute to the dictionary
+/** Add an attribute to the name table for the dictionary.
  *
  * @todo we need to check length of none vendor attributes.
  *
@@ -695,11 +695,11 @@ static fr_dict_attr_t *fr_dict_attr_alloc(TALLOC_CTX *ctx,
  * @param[in] type of attribute.
  * @param[in] flags to set in the attribute.
  * @return
- *	- 0 on success.
- *	- -1 on failure.
+ *	- fr_dict_attr_t on success
+ *	- NULL on failure
  */
-int fr_dict_attr_add(fr_dict_t *dict, fr_dict_attr_t const *parent,
-		     char const *name, int attr, PW_TYPE type, fr_dict_attr_flags_t flags)
+static fr_dict_attr_t *fr_dict_attr_add_by_name(fr_dict_t *dict, fr_dict_attr_t const *parent,
+						char const *name, int attr, PW_TYPE type, fr_dict_attr_flags_t flags)
 {
 	unsigned int		vendor;
 	size_t			namelen;
@@ -708,17 +708,17 @@ int fr_dict_attr_add(fr_dict_t *dict, fr_dict_attr_t const *parent,
 
 	INTERNAL_IF_NULL(dict);
 
-	if (!fr_cond_assert(parent)) return -1;
+	if (!fr_cond_assert(parent)) return NULL;
 
 	namelen = strlen(name);
 	if (namelen >= FR_DICT_ATTR_MAX_NAME_LEN) {
 		fr_strerror_printf("Attribute name too long");
 	error:
 		fr_strerror_printf("%s: Failed adding '%s': %s", __FUNCTION__, name, fr_strerror());
-		return -1;
+		return NULL;
 	}
 
-	if (fr_dict_valid_name(name) < 0) return -1;
+	if (fr_dict_valid_name(name) < 0) return NULL;
 
 	/*
 	 *	type_size is used to limit the maximum attribute number, so it's checked first.
@@ -877,7 +877,7 @@ int fr_dict_attr_add(fr_dict_t *dict, fr_dict_attr_t const *parent,
 
 		if (flags.length > 253) {
 			fr_strerror_printf("Invalid length %d", flags.length);
-			return -1;
+			return NULL;
 		}
 
 		if ((type == PW_TYPE_TLV) || (type == PW_TYPE_VENDOR)) {
@@ -1341,16 +1341,39 @@ int fr_dict_attr_add(fr_dict_t *dict, fr_dict_attr_t const *parent,
 		}
 	}
 
+	return n;
+}
+
+/** Add an attribute to the dictionary
+ *
+ * @todo we need to check length of none vendor attributes.
+ *
+ * @param[in] dict of protocol context we're operating in.  If NULL the internal
+ *	dictionary will be used.
+ * @param[in] parent to add attribute under.
+ * @param[in] name of the attribute.
+ * @param[in] attr number.
+ * @param[in] type of attribute.
+ * @param[in] flags to set in the attribute.
+ * @return
+ *	- 0 on success.
+ *	- -1 on failure.
+ */
+int fr_dict_attr_add(fr_dict_t *dict, fr_dict_attr_t const *parent,
+		     char const *name, int attr, PW_TYPE type, fr_dict_attr_flags_t flags)
+{
+	fr_dict_attr_t *n;
+	fr_dict_attr_t *mutable;
+
+	n = fr_dict_attr_add_by_name(dict, parent, name, attr, type, flags);
+	if (!n) return -1;
+
 	/*
 	 *	Setup parenting for the attribute
 	 */
-	{
-		fr_dict_attr_t *mutable;
-
-		memcpy(&mutable, &parent, sizeof(mutable));
+	memcpy(&mutable, &parent, sizeof(mutable));
 
-		if (fr_dict_attr_child_add(mutable, n) < 0) return -1;
-	}
+	if (fr_dict_attr_child_add(mutable, n) < 0) return -1;
 
 	return 0;
 }