1/*
2 * iterator/iter_hints.h - iterative resolver module stub and root hints.
3 *
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36/**
37 * \file
38 *
39 * This file contains functions to assist the iterator module.
40 * Keep track of stub and root hints, and read those from config.
41 */
42
43#ifndef ITERATOR_ITER_HINTS_H
44#define ITERATOR_ITER_HINTS_H
45#include "util/storage/dnstree.h"
46#include "util/locks.h"
47struct iter_env;
48struct config_file;
49struct delegpt;
50
51/**
52 * Iterator hints structure
53 */
54struct iter_hints {
55	/** lock on the forwards tree.
56	 * When grabbing both this lock and the anchors.lock, this lock
57	 * is grabbed first. */
58	lock_rw_type lock;
59	/**
60	 * Hints are stored in this tree. Sort order is specially chosen.
61	 * first sorted on qclass. Then on dname in nsec-like order, so that
62	 * a lookup on class, name will return an exact match or the closest
63	 * match which gives the ancestor needed.
64	 * contents of type iter_hints_stub. The class IN root is in here.
65	 * uses name_tree_node from dnstree.h.
66	 */
67	rbtree_type tree;
68};
69
70/**
71 * Iterator hints for a particular stub.
72 */
73struct iter_hints_stub {
74	/** tree sorted by name, class */
75	struct name_tree_node node;
76	/** delegation point with hint information for this stub. malloced. */
77	struct delegpt* dp;
78	/** does the stub need to forego priming (like on other ports) */
79	uint8_t noprime;
80};
81
82/**
83 * Create hints
84 * @return new hints or NULL on error.
85 */
86struct iter_hints* hints_create(void);
87
88/**
89 * Delete hints.
90 * @param hints: to delete.
91 */
92void hints_delete(struct iter_hints* hints);
93
94/**
95 * Process hints config. Sets default values for root hints if no config.
96 * @param hints: where to store.
97 * @param cfg: config options.
98 * @return 0 on error.
99 */
100int hints_apply_cfg(struct iter_hints* hints, struct config_file* cfg);
101
102/**
103 * Find hints for the given class.
104 * The return value is contents of the hints structure.
105 * Caller should lock and unlock a readlock on the hints structure if nolock
106 * is set.
107 * Otherwise caller should unlock the readlock on the hints structure if a
108 * value was returned.
109 * @param hints: hint storage.
110 * @param qname: the qname that generated the delegation point.
111 * @param qclass: class for which root hints are requested. host order.
112 * @param nolock: Skip locking, locking is handled by the caller.
113 * @return: NULL if no hints, or a ptr to stored hints.
114 */
115struct delegpt* hints_find(struct iter_hints* hints, uint8_t* qname,
116	uint16_t qclass, int nolock);
117
118/**
119 * Same as hints_lookup, but for the root only.
120 * @param hints: hint storage.
121 * @param qclass: class for which root hints are requested. host order.
122 * @param nolock: Skip locking, locking is handled by the caller.
123 * @return: NULL if no hints, or a ptr to stored hints.
124 */
125struct delegpt* hints_find_root(struct iter_hints* hints,
126	uint16_t qclass, int nolock);
127
128/**
129 * Find next root hints (to cycle through all root hints).
130 * Handles its own locking unless nolock is set. In that case the caller
131 * should lock and unlock a readlock on the hints structure.
132 * @param hints: hint storage
133 * @param qclass: class for which root hints are sought.
134 * 	0 means give the first available root hints class.
135 * 	x means, give class x or a higher class if any.
136 * 	returns the found class in this variable.
137 * @param nolock: Skip locking, locking is handled by the caller.
138 * @return true if a root hint class is found.
139 * 	false if not root hint class is found (qclass may have been changed).
140 */
141int hints_next_root(struct iter_hints* hints, uint16_t* qclass, int nolock);
142
143/**
144 * Given a qname/qclass combination, and the delegation point from the cache
145 * for this qname/qclass, determine if this combination indicates that a
146 * stub hint exists and must be primed.
147 * The return value is contents of the hints structure.
148 * Caller should lock and unlock a readlock on the hints structure if nolock
149 * is set.
150 * Otherwise caller should unlock the readlock on the hints structure if a
151 * value was returned.
152 *
153 * @param hints: hint storage.
154 * @param qname: The qname that generated the delegation point.
155 * @param qclass: The qclass that generated the delegation point.
156 * @param dp: The cache generated delegation point.
157 * @param nolock: Skip locking, locking is handled by the caller.
158 * @return: A priming delegation point if there is a stub hint that must
159 *         be primed, otherwise null.
160 */
161struct iter_hints_stub* hints_lookup_stub(struct iter_hints* hints,
162	uint8_t* qname, uint16_t qclass, struct delegpt* dp, int nolock);
163
164/**
165 * Get memory in use by hints
166 * Locks and unlocks the structure.
167 * @param hints: hint storage.
168 * @return bytes in use
169 */
170size_t hints_get_mem(struct iter_hints* hints);
171
172/**
173 * Add stub to hints structure. For external use since it recalcs
174 * the tree parents.
175 * Handles its own locking unless nolock is set. In that case the caller
176 * should lock and unlock a writelock on the hints structure.
177 * @param hints: the hints data structure
178 * @param c: class of zone
179 * @param dp: delegation point with name and target nameservers for new
180 *	hints stub. malloced.
181 * @param noprime: set noprime option to true or false on new hint stub.
182 * @param nolock: Skip locking, locking is handled by the caller.
183 * @return false on failure (out of memory);
184 */
185int hints_add_stub(struct iter_hints* hints, uint16_t c, struct delegpt* dp,
186	int noprime, int nolock);
187
188/**
189 * Remove stub from hints structure. For external use since it
190 * recalcs the tree parents.
191 * Handles its own locking unless nolock is set. In that case the caller
192 * should lock and unlock a writelock on the hints structure.
193 * @param hints: the hints data structure
194 * @param c: class of stub zone
195 * @param nm: name of stub zone (in uncompressed wireformat).
196 * @param nolock: Skip locking, locking is handled by the caller.
197 */
198void hints_delete_stub(struct iter_hints* hints, uint16_t c,
199	uint8_t* nm, int nolock);
200
201#endif /* ITERATOR_ITER_HINTS_H */
202