iter_fwd.h revision 238106 
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 LIMITED
25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
27 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33 * 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_t* 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_t 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 information
109 * For this qname/qclass find forward zone information, returns delegation
110 * point with server names and addresses, or NULL if no forwarding is needed.
111 *
112 * @param fwd: forward storage.
113 * @param qname: The qname of the query.
114 * @param qclass: The qclass of the query.
115 * @return: A delegation point if the query has to be forwarded to that list,
116 *         otherwise null.
117 */
118struct delegpt* forwards_lookup(struct iter_forwards* fwd,
119	uint8_t* qname, uint16_t qclass);
120
121/**
122 * Same as forwards_lookup, but for the root only
123 * @param fwd: forward storage.
124 * @param qclass: The qclass of the query.
125 * @return: A delegation point if root forward exists, otherwise null.
126 */
127struct delegpt* forwards_lookup_root(struct iter_forwards* fwd,
128	uint16_t qclass);
129
130/**
131 * Find next root item in forwards lookup tree.
132 * @param fwd: the forward storage
133 * @param qclass: class to look at next, or higher.
134 * @return false if none found, or if true stored in qclass.
135 */
136int forwards_next_root(struct iter_forwards* fwd, uint16_t* qclass);
137
138/**
139 * Get memory in use by forward storage
140 * @param fwd: forward storage.
141 * @return bytes in use
142 */
143size_t forwards_get_mem(struct iter_forwards* fwd);
144
145/** compare two fwd entries */
146int fwd_cmp(const void* k1, const void* k2);
147
148/**
149 * Add zone to forward structure. For external use since it recalcs
150 * the tree parents.
151 * @param fwd: the forward data structure
152 * @param c: class of zone
153 * @param dp: delegation point with name and target nameservers for new
154 *	forward zone. malloced.
155 * @return false on failure (out of memory);
156 */
157int forwards_add_zone(struct iter_forwards* fwd, uint16_t c,
158	struct delegpt* dp);
159
160/**
161 * Remove zone from forward structure. For external use since it
162 * recalcs the tree parents.
163 * @param fwd: the forward data structure
164 * @param c: class of zone
165 * @param nm: name of zone (in uncompressed wireformat).
166 */
167void forwards_delete_zone(struct iter_forwards* fwd, uint16_t c, uint8_t* nm);
168
169/**
170 * Add stub hole (empty entry in forward table, that makes resolution skip
171 * a forward-zone because the stub zone should override the forward zone).
172 * Does not add one if not necessary.
173 * @param fwd: the forward data structure
174 * @param c: class of zone
175 * @param nm: name of zone (in uncompressed wireformat).
176 * @return false on failure (out of memory);
177 */
178int forwards_add_stub_hole(struct iter_forwards* fwd, uint16_t c, uint8_t* nm);
179
180/**
181 * Remove stub hole, if one exists.
182 * @param fwd: the forward data structure
183 * @param c: class of zone
184 * @param nm: name of zone (in uncompressed wireformat).
185 */
186void forwards_delete_stub_hole(struct iter_forwards* fwd, uint16_t c,
187	uint8_t* nm);
188
189#endif /* ITERATOR_ITER_FWD_H */
190