unbound/iterator/iter_fwd.h

   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"
  46 struct config_file;
  47 struct delegpt;
  48
  49 /**
  50  * Iterator forward zones structure
  51  */
  52 struct 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  */
  66 struct 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  */
  91 struct iter_forwards* forwards_create(void);
  92
  93 /**
  94  * Delete forwards.
  95  * @param fwd: to delete.
  96  */
  97 void 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  */
 105 int 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  */
 114 struct 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  */
 128 struct 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  */
 137 struct 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  */
 146 int 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  */
 153 size_t forwards_get_mem(struct iter_forwards* fwd);
 154
 155 /** compare two fwd entries */
 156 int 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  */
 167 int 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  */
 177 void 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  */
 188 int 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  */
 196 void forwards_delete_stub_hole(struct iter_forwards* fwd, uint16_t c,
 197         uint8_t* nm);
 198
 199 #endif /* ITERATOR_ITER_FWD_H */