unbound/iterator/iter_hints.h

   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 struct iter_env;
  47 struct config_file;
  48 struct delegpt;
  49
  50 /**
  51  * Iterator hints structure
  52  */
  53 struct 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_t tree;
  63 };
  64
  65 /**
  66  * Iterator hints for a particular stub.
  67  */
  68 struct 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  */
  81 struct iter_hints* hints_create(void);
  82
  83 /**
  84  * Delete hints.
  85  * @param hints: to delete.
  86  */
  87 void 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  */
  95 int 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  */
 103 struct 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  */
 115 int 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  */
 129 struct 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  */
 137 size_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  */
 149 int 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  */
 159 void hints_delete_stub(struct iter_hints* hints, uint16_t c, uint8_t* nm);
 160
 161 #endif /* ITERATOR_ITER_HINTS_H */