unbound/validator/val_neg.h

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/*
* validator/val_neg.h - validator aggressive negative caching functions.
*
* Copyright (c) 2008, 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 REGENTS 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 helper functions for the validator module.
* The functions help with aggressive negative caching.
* This creates new denials of existance, and proofs for absence of types
* from cached NSEC records.
*/
#ifndef VALIDATOR_VAL_NEG_H
#define VALIDATOR_VAL_NEG_H
#include "util/locks.h"
#include "util/rbtree.h"
struct val_neg_data;
struct config_file;
struct reply_info;
struct rrset_cache;
/**
* The negative cache. It is shared between the threads, so locked.
* Kept as validator-environ-state. It refers back to the rrset cache for
* data elements. It can be out of date and contain conflicting data
* from zone content changes.
* It contains a tree of zones, every zone has a tree of data elements.
* The data elements are part of one big LRU list, with one memory counter.
*/
struct val_neg_cache {
/** the big lock on the negative cache. Because we use a rbtree
* for the data (quick lookup), we need a big lock */
lock_basic_t lock;
/** The zone rbtree. contents sorted canonical, type val_neg_zone */
rbtree_t tree;
/** the first in linked list of LRU of val_neg_data */
struct val_neg_data* first;
/** last in lru (least recently used element) */
struct val_neg_data* last;
/** current memory in use (bytes) */
size_t use;
/** max memory to use (bytes) */
size_t max;
};
/**
* Per Zone aggressive negative caching data.
*/
struct val_neg_zone {
/** rbtree node element, key is this struct: the name, class */
rbnode_t node;
/** name; the key */
uint8_t* name;
/** length of name */
size_t len;
/** labels in name */
int labs;
/** pointer to parent zone in the negative cache */
struct val_neg_zone* parent;
/** the number of elements, including this one and the ones whose
* parents (-parents) include this one, that are in_use
* No elements have a count of zero, those are removed. */
int count;
/* type of zone ; NSEC */
/** tree of NSEC data for this zone, sorted canonical
* by NSEC owner name */
rbtree_t tree;
/** class of node; host order */
uint16_t dclass;
/** if this element is in use, boolean */
uint8_t in_use;
};
/**
* Data element for aggressive negative caching.
* The tree of these elements acts as an index onto the rrset cache.
* It shows the NSEC records that (may) exist and are (possibly) secure.
* The rbtree allows for logN search for a covering NSEC record.
* To make tree insertion and deletion logN too, all the parent (one label
* less than the name) data elements are also in the rbtree, with a usage
* count for every data element.
* There is no actual data stored in this data element, if it is in_use,
* then the data can (possibly) be found in the rrset cache.
*/
struct val_neg_data {
/** rbtree node element, key is this struct: the name */
rbnode_t node;
/** name; the key */
uint8_t* name;
/** length of name */
size_t len;
/** labels in name */
int labs;
/** pointer to parent node in the negative cache */
struct val_neg_data* parent;
/** the number of elements, including this one and the ones whose
* parents (-parents) include this one, that are in use
* No elements have a count of zero, those are removed. */
int count;
/** the zone that this denial is part of */
struct val_neg_zone* zone;
/** previous in LRU */
struct val_neg_data* prev;
/** next in LRU (next element was less recently used) */
struct val_neg_data* next;
/** if this element is in use, boolean */
uint8_t in_use;
};
/**
* Create negative cache
* @return neg cache, empty or NULL on failure.
*/
struct val_neg_cache* val_neg_create();
/**
* Apply configuration settings to negative cache
* @param neg: negative cache.
* @param cfg: config options.
* @return false on error.
*/
int val_neg_apply_cfg(struct val_neg_cache* neg, struct config_file* cfg);
/**
* see how much memory is in use by the negative cache.
* @param neg: negative cache
* @return number of bytes in use.
*/
size_t val_neg_get_mem(struct val_neg_cache* neg);
/**
* Destroy negative cache. There must no longer be any other threads.
* @param neg: negative cache.
*/
void neg_cache_delete(struct val_neg_cache* neg);
/**
* Comparison function for rbtree val neg data elements
*/
int val_neg_data_compare(const void* a, const void* b);
/**
* Comparison function for rbtree val neg zone elements
*/
int val_neg_zone_compare(const void* a, const void* b);
/**
* Insert NSECs from this message into the negative cache for reference.
* @param neg: negative cache
* @param rep: reply with NSECs.
* Errors are ignored, means that storage is omitted.
*/
void val_neg_addreply(struct val_neg_cache* neg, struct reply_info* rep);
/**
* Perform a DLV style lookup
* During the lookup, we could find out that data has expired. In that
* case the neg_cache entries are removed, and lookup fails.
*
* @param neg: negative cache.
* @param qname: name to look for
* @param len: length of qname.
* @param qclass: class to look in.
* @param rrset_cache: the rrset cache, for NSEC lookups.
* @param now: current time for ttl checks.
* @return
* 0 on error
* 0 if no proof of negative
* 1 if indeed negative was proven
* thus, qname DLV qclass does not exist.
*/
int val_neg_dlvlookup(struct val_neg_cache* neg, uint8_t* qname, size_t len,
uint16_t qclass, struct rrset_cache* rrset_cache, uint32_t now);
#endif /* VALIDATOR_VAL_NEG_H */