Very first API for node.

Just basic functions declared:
- creating node
- destroying node
- adding RRSet
- getting RRSet
- getting parent of a node

refs #88

src/dnslib/node.h

+/*!
+ * \file node.h
+ * \author Lubos Slovak <lubos.slovak@nic.cz>
+ *
+ * \brief Structure representing one done in domain name tree and API for
+ *        manipulating it.
+ *
+ * \addtogroup dnslib
+ * @{
+ */
+
 #ifndef _CUTEDNS_NODE_H
 #define _CUTEDNS_NODE_H
 
 #include "dname.h"
 #include "skip-list.h"
+#include "rrset.h"
 
+/*----------------------------------------------------------------------------*/
+/*!
+ * \brief Structure representing one node in a domain name tree, i.e. one domain
+ *        name in a zone.
+ *
+ * RRSets are ordered by type and stored in a skip-list to allow fast lookup.
+ *
+ * \todo How to return all RRSets?? An array? Or return the skip list and let
+ *       the user iterate over it?
+ */
 struct dnslib_node {
-	dnslib_dname_t *owner;
-	struct dnslib_node *parent;
-	skip_list *rrsets;	// key - RRTYPE (uint16_t); value - dnslib_rrset_t *
+	dnslib_dname_t *owner;	/*!< Domain name being the owner of this node. */
+	struct dnslib_node *parent;	/*!< Parent node in the name hierarchy. */
+	/*! \brief Type-ordered list of RRSets belonging to this node. */
+	skip_list *rrsets;
 
-	struct dnslib_node *next;	// temporary
+	/*! \brief Next node in a general list of nodes. Temporary. */
+	struct dnslib_node *next;
 };
 
 typedef struct dnslib_node dnslib_node_t;
 
+/*----------------------------------------------------------------------------*/
+/*!
+ * \brief Creates and initializes new node structure.
+ *
+ * \param owner Owner of the created node.
+ * \param parent Parent of the created node.
+ *
+ * \return Newly created node or NULL if an error occured.
+ */
+dnslib_node_t *dnslib_node_new( dnslib_dname_t *owner, dnslib_node *parent );
+
+/*!
+ * \brief Adds an RRSet to the node.
+ *
+ * \param node Node to add the RRSet to.
+ * \param rrset RRSet to add.
+ *
+ * \retval 0 on success.
+ * \retval <> 0 on failure.
+ *
+ * \todo Specify return values according to implementation.
+ */
+int dnslib_node_add_rrset( dnslib_node_t *node, dnslib_rrset_t *rrset );
+
+/*!
+ * \brief Returns the RRSet of the given type from the node.
+ *
+ * \param node Node to get the RRSet from.
+ * \param type Type of the RRSet to retrieve.
+ *
+ * \return RRSet from node \a node having type \a type, or NULL if no such
+ *         RRSet exists in this node.
+ */
+const dnslib_rrset_t *dnslib_node_get_rrset( const dnslib_node_t *node,
+											 uint16_t type );
+
+/*!
+ * \brief Returns the parent of the node.
+ *
+ * \param node Node to get the parent of.
+ *
+ * \return Parent node of the given node or NULL if no parent has been set (e.g.
+ *         node in a zone apex has no parent).
+ */
+const dnslib_node_t *dnslib_node_get_parent( const dnslib_node_t *node );
+
+/*!
+ * \brief Destroys the node structure.
+ *
+ * \param node Node to be destroyed.
+ *
+ * Sets the given pointer to NULL.
+ */
+void dnslib_node_free( dnslib_node_t **node );
+
 #endif /* _CUTEDNS_NODE_H */
+
+/*! @} */