1 /* 2 * iterator/iter_resptype.h - response type information and classification. 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 defines the response type. DNS Responses can be classified as 40 * one of the response types. 41 */ 42 43 #ifndef ITERATOR_ITER_RESPTYPE_H 44 #define ITERATOR_ITER_RESPTYPE_H 45 struct dns_msg; 46 struct query_info; 47 struct delegpt; 48 49 /** 50 * The response type is used to interpret the response. 51 */ 52 enum response_type { 53 /** 54 * 'untyped' means that the type of this response hasn't been 55 * assigned. 56 */ 57 RESPONSE_TYPE_UNTYPED = 0, 58 59 /** 60 * 'answer' means that the response terminates the resolution 61 * process. 62 */ 63 RESPONSE_TYPE_ANSWER, 64 65 /** 'delegation' means that the response is a delegation. */ 66 RESPONSE_TYPE_REFERRAL, 67 68 /** 69 * 'cname' means that the response is a cname without the final 70 * answer, and thus must be restarted. 71 */ 72 RESPONSE_TYPE_CNAME, 73 74 /** 75 * 'throwaway' means that this particular response should be 76 * discarded and the next nameserver should be contacted 77 */ 78 RESPONSE_TYPE_THROWAWAY, 79 80 /** 81 * 'lame' means that this particular response indicates that 82 * the nameserver knew nothing about the question. 83 */ 84 RESPONSE_TYPE_LAME, 85 86 /** 87 * Recursion lame means that the nameserver is some sort of 88 * open recursor, and not authoritative for the question. 89 * It may know something, but not authoritatively. 90 */ 91 RESPONSE_TYPE_REC_LAME 92 }; 93 94 /** 95 * Classifies a response message from cache based on the current request. 96 * Note that this routine assumes that THROWAWAY or LAME responses will not 97 * occur. Also, it will not detect REFERRAL type messages, since those are 98 * (currently) automatically classified based on how they came from the 99 * cache (findDelegation() instead of lookup()). 100 * 101 * @param msg: the message from the cache. 102 * @param request: the request that generated the response. 103 * @return the response type (CNAME or ANSWER). 104 */ 105 enum response_type response_type_from_cache(struct dns_msg* msg, 106 struct query_info* request); 107 108 /** 109 * Classifies a response message (from the wire) based on the current 110 * request. 111 * 112 * NOTE: currently this routine uses the AA bit in the response to help 113 * distinguish between some non-standard referrals and answers. It also 114 * relies somewhat on the originating zone to be accurate (for lameness 115 * detection, mostly). 116 * 117 * @param rdset: if RD bit was sent in query sent by unbound. 118 * @param msg: the message from the cache. 119 * @param request: the request that generated the response. 120 * @param dp: The delegation point that was being queried 121 * when the response was returned. 122 * @param empty_nodata_found: flag to keep track of empty nodata detection. 123 * @return the response type (CNAME or ANSWER). 124 */ 125 enum response_type response_type_from_server(int rdset, 126 struct dns_msg* msg, struct query_info* request, struct delegpt* dp, 127 int* empty_nodata_found); 128 129 #endif /* ITERATOR_ITER_RESPTYPE_H */ 130