323 lines
11 KiB
C
323 lines
11 KiB
C
/*
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* validator/val_neg.h - validator aggressive negative caching functions.
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*
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* Copyright (c) 2008, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \file
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*
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* This file contains helper functions for the validator module.
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* The functions help with aggressive negative caching.
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* This creates new denials of existence, and proofs for absence of types
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* from cached NSEC records.
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*/
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#ifndef VALIDATOR_VAL_NEG_H
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#define VALIDATOR_VAL_NEG_H
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#include "util/locks.h"
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#include "util/rbtree.h"
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struct sldns_buffer;
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struct val_neg_data;
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struct config_file;
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struct reply_info;
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struct rrset_cache;
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struct regional;
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struct query_info;
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struct dns_msg;
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struct ub_packed_rrset_key;
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/**
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* The negative cache. It is shared between the threads, so locked.
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* Kept as validator-environ-state. It refers back to the rrset cache for
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* data elements. It can be out of date and contain conflicting data
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* from zone content changes.
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* It contains a tree of zones, every zone has a tree of data elements.
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* The data elements are part of one big LRU list, with one memory counter.
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*/
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struct val_neg_cache {
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/** the big lock on the negative cache. Because we use a rbtree
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* for the data (quick lookup), we need a big lock */
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lock_basic_type lock;
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/** The zone rbtree. contents sorted canonical, type val_neg_zone */
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rbtree_type tree;
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/** the first in linked list of LRU of val_neg_data */
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struct val_neg_data* first;
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/** last in lru (least recently used element) */
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struct val_neg_data* last;
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/** current memory in use (bytes) */
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size_t use;
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/** max memory to use (bytes) */
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size_t max;
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/** max nsec3 iterations allowed */
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size_t nsec3_max_iter;
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/** number of times neg cache records were used to generate NOERROR
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* responses. */
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size_t num_neg_cache_noerror;
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/** number of times neg cache records were used to generate NXDOMAIN
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* responses. */
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size_t num_neg_cache_nxdomain;
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};
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/**
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* Per Zone aggressive negative caching data.
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*/
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struct val_neg_zone {
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/** rbtree node element, key is this struct: the name, class */
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rbnode_type node;
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/** name; the key */
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uint8_t* name;
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/** length of name */
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size_t len;
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/** labels in name */
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int labs;
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/** pointer to parent zone in the negative cache */
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struct val_neg_zone* parent;
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/** the number of elements, including this one and the ones whose
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* parents (-parents) include this one, that are in_use
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* No elements have a count of zero, those are removed. */
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int count;
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/** if 0: NSEC zone, else NSEC3 hash algorithm in use */
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int nsec3_hash;
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/** nsec3 iteration count in use */
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size_t nsec3_iter;
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/** nsec3 salt in use */
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uint8_t* nsec3_salt;
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/** length of salt in bytes */
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size_t nsec3_saltlen;
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/** tree of NSEC data for this zone, sorted canonical
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* by NSEC owner name */
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rbtree_type tree;
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/** class of node; host order */
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uint16_t dclass;
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/** if this element is in use, boolean */
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uint8_t in_use;
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};
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/**
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* Data element for aggressive negative caching.
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* The tree of these elements acts as an index onto the rrset cache.
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* It shows the NSEC records that (may) exist and are (possibly) secure.
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* The rbtree allows for logN search for a covering NSEC record.
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* To make tree insertion and deletion logN too, all the parent (one label
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* less than the name) data elements are also in the rbtree, with a usage
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* count for every data element.
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* There is no actual data stored in this data element, if it is in_use,
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* then the data can (possibly) be found in the rrset cache.
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*/
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struct val_neg_data {
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/** rbtree node element, key is this struct: the name */
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rbnode_type node;
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/** name; the key */
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uint8_t* name;
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/** length of name */
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size_t len;
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/** labels in name */
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int labs;
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/** pointer to parent node in the negative cache */
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struct val_neg_data* parent;
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/** the number of elements, including this one and the ones whose
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* parents (-parents) include this one, that are in use
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* No elements have a count of zero, those are removed. */
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int count;
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/** the zone that this denial is part of */
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struct val_neg_zone* zone;
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/** previous in LRU */
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struct val_neg_data* prev;
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/** next in LRU (next element was less recently used) */
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struct val_neg_data* next;
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/** if this element is in use, boolean */
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uint8_t in_use;
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};
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/**
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* Create negative cache
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* @param cfg: config options.
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* @param maxiter: max nsec3 iterations allowed.
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* @return neg cache, empty or NULL on failure.
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*/
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struct val_neg_cache* val_neg_create(struct config_file* cfg, size_t maxiter);
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/**
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* see how much memory is in use by the negative cache.
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* @param neg: negative cache
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* @return number of bytes in use.
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*/
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size_t val_neg_get_mem(struct val_neg_cache* neg);
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/**
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* Destroy negative cache. There must no longer be any other threads.
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* @param neg: negative cache.
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*/
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void neg_cache_delete(struct val_neg_cache* neg);
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/**
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* Comparison function for rbtree val neg data elements
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*/
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int val_neg_data_compare(const void* a, const void* b);
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/**
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* Comparison function for rbtree val neg zone elements
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*/
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int val_neg_zone_compare(const void* a, const void* b);
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/**
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* Insert NSECs from this message into the negative cache for reference.
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* @param neg: negative cache
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* @param rep: reply with NSECs.
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* Errors are ignored, means that storage is omitted.
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*/
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void val_neg_addreply(struct val_neg_cache* neg, struct reply_info* rep);
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/**
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* Insert NSECs from this referral into the negative cache for reference.
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* @param neg: negative cache
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* @param rep: referral reply with NS, NSECs.
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* @param zone: bailiwick for the referral.
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* Errors are ignored, means that storage is omitted.
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*/
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void val_neg_addreferral(struct val_neg_cache* neg, struct reply_info* rep,
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uint8_t* zone);
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/**
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* Perform a DLV style lookup
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* During the lookup, we could find out that data has expired. In that
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* case the neg_cache entries are removed, and lookup fails.
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*
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* @param neg: negative cache.
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* @param qname: name to look for
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* @param len: length of qname.
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* @param qclass: class to look in.
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* @param rrset_cache: the rrset cache, for NSEC lookups.
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* @param now: current time for ttl checks.
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* @return
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* 0 on error
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* 0 if no proof of negative
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* 1 if indeed negative was proven
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* thus, qname DLV qclass does not exist.
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*/
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int val_neg_dlvlookup(struct val_neg_cache* neg, uint8_t* qname, size_t len,
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uint16_t qclass, struct rrset_cache* rrset_cache, time_t now);
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/**
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* For the given query, try to get a reply out of the negative cache.
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* The reply still needs to be validated.
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* @param neg: negative cache.
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* @param qinfo: query
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* @param region: where to allocate reply.
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* @param rrset_cache: rrset cache.
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* @param buf: temporary buffer.
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* @param now: to check TTLs against.
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* @param addsoa: if true, produce result for external consumption.
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* if false, do not add SOA - for unbound-internal consumption.
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* @param topname: do not look higher than this name,
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* so that the result cannot be taken from a zone above the current
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* trust anchor. Which could happen with multiple islands of trust.
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* if NULL, then no trust anchor is used, but also the algorithm becomes
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* more conservative, especially for opt-out zones, since the receiver
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* may have a trust-anchor below the optout and thus the optout cannot
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* be used to create a proof from the negative cache.
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* @param cfg: config options.
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* @return a reply message if something was found.
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* This reply may still need validation.
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* NULL if nothing found (or out of memory).
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*/
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struct dns_msg* val_neg_getmsg(struct val_neg_cache* neg,
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struct query_info* qinfo, struct regional* region,
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struct rrset_cache* rrset_cache, struct sldns_buffer* buf, time_t now,
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int addsoa, uint8_t* topname, struct config_file* cfg);
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/**** functions exposed for unit test ****/
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/**
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* Insert data into the data tree of a zone
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* Does not do locking.
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* @param neg: negative cache
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* @param zone: zone to insert into
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* @param nsec: record to insert.
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*/
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void neg_insert_data(struct val_neg_cache* neg,
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struct val_neg_zone* zone, struct ub_packed_rrset_key* nsec);
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/**
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* Delete a data element from the negative cache.
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* May delete other data elements to keep tree coherent, or
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* only mark the element as 'not in use'.
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* Does not do locking.
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* @param neg: negative cache.
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* @param el: data element to delete.
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*/
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void neg_delete_data(struct val_neg_cache* neg, struct val_neg_data* el);
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/**
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* Find the given zone, from the SOA owner name and class
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* Does not do locking.
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* @param neg: negative cache
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* @param nm: what to look for.
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* @param len: length of nm
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* @param dclass: class to look for.
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* @return zone or NULL if not found.
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*/
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struct val_neg_zone* neg_find_zone(struct val_neg_cache* neg,
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uint8_t* nm, size_t len, uint16_t dclass);
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/**
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* Create a new zone.
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* Does not do locking.
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* @param neg: negative cache
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* @param nm: what to look for.
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* @param nm_len: length of name.
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* @param dclass: class of zone, host order.
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* @return zone or NULL if out of memory.
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*/
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struct val_neg_zone* neg_create_zone(struct val_neg_cache* neg,
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uint8_t* nm, size_t nm_len, uint16_t dclass);
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/**
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* take a zone into use. increases counts of parents.
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* Does not do locking.
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* @param zone: zone to take into use.
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*/
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void val_neg_zone_take_inuse(struct val_neg_zone* zone);
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#endif /* VALIDATOR_VAL_NEG_H */
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