iter_fwd.h revision 356345 
1/*
2 * iterator/iter_fwd.h - iterative resolver module forward zones.
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 forward zones, and read those from config.
41 */
42
43#ifndef ITERATOR_ITER_FWD_H
44#define ITERATOR_ITER_FWD_H
45#include "util/rbtree.h"
46struct config_file;
47struct delegpt;
48
49/**
50 * Iterator forward zones structure
51 */
52struct iter_forwards {
53	/**
54	 * Zones are stored in this tree. Sort order is specially chosen.
55	 * first sorted on qclass. Then on dname in nsec-like order, so that
56	 * a lookup on class, name will return an exact match or the closest
57	 * match which gives the ancestor needed.
58	 * contents of type iter_forward_zone.
59	 */
60	rbtree_type* tree;
61};
62
63/**
64 * Iterator forward servers for a particular zone.
65 */
66struct iter_forward_zone {
67	/** redblacktree node, key is this structure: class and name */
68	rbnode_type node;
69	/** name */
70	uint8_t* name;
71	/** length of name */
72	size_t namelen;
73	/** number of labels in name */
74	int namelabs;
75	/** delegation point with forward server information for this zone.
76	 * If NULL then this forward entry is used to indicate that a
77	 * stub-zone with the same name exists, and should be used.
78	 * This delegation point is malloced.
79	 */
80	struct delegpt* dp;
81	/** pointer to parent in tree (or NULL if none) */
82	struct iter_forward_zone* parent;
83	/** class. host order. */
84	uint16_t dclass;
85};
86
87/**
88 * Create forwards
89 * @return new forwards or NULL on error.
90 */
91struct iter_forwards* forwards_create(void);
92
93/**
94 * Delete forwards.
95 * @param fwd: to delete.
96 */
97void forwards_delete(struct iter_forwards* fwd);
98
99/**
100 * Process forwards config.
101 * @param fwd: where to store.
102 * @param cfg: config options.
103 * @return 0 on error.
104 */
105int forwards_apply_cfg(struct iter_forwards* fwd, struct config_file* cfg);
106
107/**
108 * Find forward zone exactly by name
109 * @param fwd: forward storage.
110 * @param qname: The qname of the query.
111 * @param qclass: The qclass of the query.
112 * @return: A delegation point or null.
113 */
114struct delegpt* forwards_find(struct iter_forwards* fwd, uint8_t* qname,
115	uint16_t qclass);
116
117/**
118 * Find forward zone information
119 * For this qname/qclass find forward zone information, returns delegation
120 * point with server names and addresses, or NULL if no forwarding is needed.
121 *
122 * @param fwd: forward storage.
123 * @param qname: The qname of the query.
124 * @param qclass: The qclass of the query.
125 * @return: A delegation point if the query has to be forwarded to that list,
126 *         otherwise null.
127 */
128struct delegpt* forwards_lookup(struct iter_forwards* fwd,
129	uint8_t* qname, uint16_t qclass);
130
131/**
132 * Same as forwards_lookup, but for the root only
133 * @param fwd: forward storage.
134 * @param qclass: The qclass of the query.
135 * @return: A delegation point if root forward exists, otherwise null.
136 */
137struct delegpt* forwards_lookup_root(struct iter_forwards* fwd,
138	uint16_t qclass);
139
140/**
141 * Find next root item in forwards lookup tree.
142 * @param fwd: the forward storage
143 * @param qclass: class to look at next, or higher.
144 * @return false if none found, or if true stored in qclass.
145 */
146int forwards_next_root(struct iter_forwards* fwd, uint16_t* qclass);
147
148/**
149 * Get memory in use by forward storage
150 * @param fwd: forward storage.
151 * @return bytes in use
152 */
153size_t forwards_get_mem(struct iter_forwards* fwd);
154
155/** compare two fwd entries */
156int fwd_cmp(const void* k1, const void* k2);
157
158/**
159 * Add zone to forward structure. For external use since it recalcs
160 * the tree parents.
161 * @param fwd: the forward data structure
162 * @param c: class of zone
163 * @param dp: delegation point with name and target nameservers for new
164 *	forward zone. malloced.
165 * @return false on failure (out of memory);
166 */
167int forwards_add_zone(struct iter_forwards* fwd, uint16_t c,
168	struct delegpt* dp);
169
170/**
171 * Remove zone from forward structure. For external use since it
172 * recalcs the tree parents.
173 * @param fwd: the forward data structure
174 * @param c: class of zone
175 * @param nm: name of zone (in uncompressed wireformat).
176 */
177void forwards_delete_zone(struct iter_forwards* fwd, uint16_t c, uint8_t* nm);
178
179/**
180 * Add stub hole (empty entry in forward table, that makes resolution skip
181 * a forward-zone because the stub zone should override the forward zone).
182 * Does not add one if not necessary.
183 * @param fwd: the forward data structure
184 * @param c: class of zone
185 * @param nm: name of zone (in uncompressed wireformat).
186 * @return false on failure (out of memory);
187 */
188int forwards_add_stub_hole(struct iter_forwards* fwd, uint16_t c, uint8_t* nm);
189
190/**
191 * Remove stub hole, if one exists.
192 * @param fwd: the forward data structure
193 * @param c: class of zone
194 * @param nm: name of zone (in uncompressed wireformat).
195 */
196void forwards_delete_stub_hole(struct iter_forwards* fwd, uint16_t c,
197	uint8_t* nm);
198
199#endif /* ITERATOR_ITER_FWD_H */
200