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 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 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
45struct dns_msg;
46struct query_info;
47struct delegpt;
48
49/**
50 * The response type is used to interpret the response.
51 */
52enum 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 */
105enum 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 * @return the response type (CNAME or ANSWER).
123 */
124enum response_type response_type_from_server(int rdset,
125	struct dns_msg* msg, struct query_info* request, struct delegpt* dp);
126
127#endif /* ITERATOR_ITER_RESPTYPE_H */
128