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/*
* iterator/iter_hints.h - iterative resolver module stub and root hints.
*
* Copyright (c) 2007, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \file
*
* This file contains functions to assist the iterator module.
* Keep track of stub and root hints, and read those from config.
*/
#ifndef ITERATOR_ITER_HINTS_H
#define ITERATOR_ITER_HINTS_H
#include "util/storage/dnstree.h"
#include "util/locks.h"
struct iter_env;
struct config_file;
struct delegpt;
/**
* Iterator hints structure
*/
struct iter_hints {
/** lock on the forwards tree.
* When grabbing both this lock and the anchors.lock, this lock
* is grabbed first. */
lock_rw_type lock;
/**
* Hints are stored in this tree. Sort order is specially chosen.
* first sorted on qclass. Then on dname in nsec-like order, so that
* a lookup on class, name will return an exact match or the closest
* match which gives the ancestor needed.
* contents of type iter_hints_stub. The class IN root is in here.
* uses name_tree_node from dnstree.h.
*/
rbtree_type tree;
};
/**
* Iterator hints for a particular stub.
*/
struct iter_hints_stub {
/** tree sorted by name, class */
struct name_tree_node node;
/** delegation point with hint information for this stub. malloced. */
struct delegpt* dp;
/** does the stub need to forego priming (like on other ports) */
uint8_t noprime;
};
/**
* Create hints
* @return new hints or NULL on error.
*/
struct iter_hints* hints_create(void);
/**
* Delete hints.
* @param hints: to delete.
*/
void hints_delete(struct iter_hints* hints);
/**
* Process hints config. Sets default values for root hints if no config.
* @param hints: where to store.
* @param cfg: config options.
* @return 0 on error.
*/
int hints_apply_cfg(struct iter_hints* hints, struct config_file* cfg);
/**
* Find hints for the given class.
* The return value is contents of the hints structure.
* Caller should lock and unlock a readlock on the hints structure if nolock
* is set.
* Otherwise caller should unlock the readlock on the hints structure if a
* value was returned.
* @param hints: hint storage.
* @param qname: the qname that generated the delegation point.
* @param qclass: class for which root hints are requested. host order.
* @param nolock: Skip locking, locking is handled by the caller.
* @return: NULL if no hints, or a ptr to stored hints.
*/
struct delegpt* hints_find(struct iter_hints* hints, uint8_t* qname,
uint16_t qclass, int nolock);
/**
* Same as hints_lookup, but for the root only.
* @param hints: hint storage.
* @param qclass: class for which root hints are requested. host order.
* @param nolock: Skip locking, locking is handled by the caller.
* @return: NULL if no hints, or a ptr to stored hints.
*/
struct delegpt* hints_find_root(struct iter_hints* hints,
uint16_t qclass, int nolock);
/**
* Find next root hints (to cycle through all root hints).
* Handles its own locking unless nolock is set. In that case the caller
* should lock and unlock a readlock on the hints structure.
* @param hints: hint storage
* @param qclass: class for which root hints are sought.
* 0 means give the first available root hints class.
* x means, give class x or a higher class if any.
* returns the found class in this variable.
* @param nolock: Skip locking, locking is handled by the caller.
* @return true if a root hint class is found.
* false if not root hint class is found (qclass may have been changed).
*/
int hints_next_root(struct iter_hints* hints, uint16_t* qclass, int nolock);
/**
* Given a qname/qclass combination, and the delegation point from the cache
* for this qname/qclass, determine if this combination indicates that a
* stub hint exists and must be primed.
* The return value is contents of the hints structure.
* Caller should lock and unlock a readlock on the hints structure if nolock
* is set.
* Otherwise caller should unlock the readlock on the hints structure if a
* value was returned.
*
* @param hints: hint storage.
* @param qname: The qname that generated the delegation point.
* @param qclass: The qclass that generated the delegation point.
* @param dp: The cache generated delegation point.
* @param nolock: Skip locking, locking is handled by the caller.
* @return: A priming delegation point if there is a stub hint that must
* be primed, otherwise null.
*/
struct iter_hints_stub* hints_lookup_stub(struct iter_hints* hints,
uint8_t* qname, uint16_t qclass, struct delegpt* dp, int nolock);
/**
* Get memory in use by hints
* Locks and unlocks the structure.
* @param hints: hint storage.
* @return bytes in use
*/
size_t hints_get_mem(struct iter_hints* hints);
/**
* Add stub to hints structure. For external use since it recalcs
* the tree parents.
* Handles its own locking unless nolock is set. In that case the caller
* should lock and unlock a writelock on the hints structure.
* @param hints: the hints data structure
* @param c: class of zone
* @param dp: delegation point with name and target nameservers for new
* hints stub. malloced.
* @param noprime: set noprime option to true or false on new hint stub.
* @param nolock: Skip locking, locking is handled by the caller.
* @return false on failure (out of memory);
*/
int hints_add_stub(struct iter_hints* hints, uint16_t c, struct delegpt* dp,
int noprime, int nolock);
/**
* Remove stub from hints structure. For external use since it
* recalcs the tree parents.
* Handles its own locking unless nolock is set. In that case the caller
* should lock and unlock a writelock on the hints structure.
* @param hints: the hints data structure
* @param c: class of stub zone
* @param nm: name of stub zone (in uncompressed wireformat).
* @param nolock: Skip locking, locking is handled by the caller.
*/
void hints_delete_stub(struct iter_hints* hints, uint16_t c,
uint8_t* nm, int nolock);
/**
* Swap internal tree with preallocated entries. Caller should manage
* the locks.
* @param hints: the hints data structure.
* @param data: the data structure used to take elements from. This contains
* the old elements on return.
*/
void hints_swap_tree(struct iter_hints* hints, struct iter_hints* data);
#endif /* ITERATOR_ITER_HINTS_H */
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