iter_hints.h revision 356345 
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"
46struct iter_env;
47struct config_file;
48struct delegpt;
49
50/**
51 * Iterator hints structure
52 */
53struct iter_hints {
54	/**
55	 * Hints are stored in this tree. Sort order is specially chosen.
56	 * first sorted on qclass. Then on dname in nsec-like order, so that
57	 * a lookup on class, name will return an exact match or the closest
58	 * match which gives the ancestor needed.
59	 * contents of type iter_hints_stub. The class IN root is in here.
60	 * uses name_tree_node from dnstree.h.
61	 */
62	rbtree_type tree;
63};
64
65/**
66 * Iterator hints for a particular stub.
67 */
68struct iter_hints_stub {
69	/** tree sorted by name, class */
70	struct name_tree_node node;
71	/** delegation point with hint information for this stub. malloced. */
72	struct delegpt* dp;
73	/** does the stub need to forego priming (like on other ports) */
74	uint8_t noprime;
75};
76
77/**
78 * Create hints
79 * @return new hints or NULL on error.
80 */
81struct iter_hints* hints_create(void);
82
83/**
84 * Delete hints.
85 * @param hints: to delete.
86 */
87void hints_delete(struct iter_hints* hints);
88
89/**
90 * Process hints config. Sets default values for root hints if no config.
91 * @param hints: where to store.
92 * @param cfg: config options.
93 * @return 0 on error.
94 */
95int hints_apply_cfg(struct iter_hints* hints, struct config_file* cfg);
96
97/**
98 * Find root hints for the given class.
99 * @param hints: hint storage.
100 * @param qclass: class for which root hints are requested. host order.
101 * @return: NULL if no hints, or a ptr to stored hints.
102 */
103struct delegpt* hints_lookup_root(struct iter_hints* hints, uint16_t qclass);
104
105/**
106 * Find next root hints (to cycle through all root hints).
107 * @param hints: hint storage
108 * @param qclass: class for which root hints are sought.
109 * 	0 means give the first available root hints class.
110 * 	x means, give class x or a higher class if any.
111 * 	returns the found class in this variable.
112 * @return true if a root hint class is found.
113 * 	false if not root hint class is found (qclass may have been changed).
114 */
115int hints_next_root(struct iter_hints* hints, uint16_t* qclass);
116
117/**
118 * Given a qname/qclass combination, and the delegation point from the cache
119 * for this qname/qclass, determine if this combination indicates that a
120 * stub hint exists and must be primed.
121 *
122 * @param hints: hint storage.
123 * @param qname: The qname that generated the delegation point.
124 * @param qclass: The qclass that generated the delegation point.
125 * @param dp: The cache generated delegation point.
126 * @return: A priming delegation point if there is a stub hint that must
127 *         be primed, otherwise null.
128 */
129struct iter_hints_stub* hints_lookup_stub(struct iter_hints* hints,
130	uint8_t* qname, uint16_t qclass, struct delegpt* dp);
131
132/**
133 * Get memory in use by hints
134 * @param hints: hint storage.
135 * @return bytes in use
136 */
137size_t hints_get_mem(struct iter_hints* hints);
138
139/**
140 * Add stub to hints structure. For external use since it recalcs
141 * the tree parents.
142 * @param hints: the hints data structure
143 * @param c: class of zone
144 * @param dp: delegation point with name and target nameservers for new
145 *	hints stub. malloced.
146 * @param noprime: set noprime option to true or false on new hint stub.
147 * @return false on failure (out of memory);
148 */
149int hints_add_stub(struct iter_hints* hints, uint16_t c, struct delegpt* dp,
150	int noprime);
151
152/**
153 * Remove stub from hints structure. For external use since it
154 * recalcs the tree parents.
155 * @param hints: the hints data structure
156 * @param c: class of stub zone
157 * @param nm: name of stub zone (in uncompressed wireformat).
158 */
159void hints_delete_stub(struct iter_hints* hints, uint16_t c, uint8_t* nm);
160
161#endif /* ITERATOR_ITER_HINTS_H */
162