130 lines
4.4 KiB
C
130 lines
4.4 KiB
C
/*
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* iterator/iter_resptype.h - response type information and classification.
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*
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* Copyright (c) 2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \file
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*
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* This file defines the response type. DNS Responses can be classified as
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* one of the response types.
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*/
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#ifndef ITERATOR_ITER_RESPTYPE_H
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#define ITERATOR_ITER_RESPTYPE_H
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struct dns_msg;
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struct query_info;
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struct delegpt;
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/**
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* The response type is used to interpret the response.
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*/
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enum response_type {
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/**
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* 'untyped' means that the type of this response hasn't been
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* assigned.
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*/
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RESPONSE_TYPE_UNTYPED = 0,
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/**
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* 'answer' means that the response terminates the resolution
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* process.
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*/
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RESPONSE_TYPE_ANSWER,
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/** 'delegation' means that the response is a delegation. */
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RESPONSE_TYPE_REFERRAL,
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/**
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* 'cname' means that the response is a cname without the final
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* answer, and thus must be restarted.
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*/
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RESPONSE_TYPE_CNAME,
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/**
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* 'throwaway' means that this particular response should be
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* discarded and the next nameserver should be contacted
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*/
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RESPONSE_TYPE_THROWAWAY,
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/**
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* 'lame' means that this particular response indicates that
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* the nameserver knew nothing about the question.
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*/
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RESPONSE_TYPE_LAME,
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/**
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* Recursion lame means that the nameserver is some sort of
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* open recursor, and not authoritative for the question.
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* It may know something, but not authoritatively.
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*/
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RESPONSE_TYPE_REC_LAME
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};
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/**
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* Classifies a response message from cache based on the current request.
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* Note that this routine assumes that THROWAWAY or LAME responses will not
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* occur. Also, it will not detect REFERRAL type messages, since those are
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* (currently) automatically classified based on how they came from the
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* cache (findDelegation() instead of lookup()).
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*
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* @param msg: the message from the cache.
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* @param request: the request that generated the response.
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* @return the response type (CNAME or ANSWER).
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*/
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enum response_type response_type_from_cache(struct dns_msg* msg,
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struct query_info* request);
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/**
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* Classifies a response message (from the wire) based on the current
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* request.
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*
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* NOTE: currently this routine uses the AA bit in the response to help
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* distinguish between some non-standard referrals and answers. It also
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* relies somewhat on the originating zone to be accurate (for lameness
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* detection, mostly).
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*
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* @param rdset: if RD bit was sent in query sent by unbound.
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* @param msg: the message from the cache.
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* @param request: the request that generated the response.
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* @param dp: The delegation point that was being queried
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* when the response was returned.
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* @param empty_nodata_found: flag to keep track of empty nodata detection.
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* @return the response type (CNAME or ANSWER).
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*/
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enum response_type response_type_from_server(int rdset,
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struct dns_msg* msg, struct query_info* request, struct delegpt* dp,
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int* empty_nodata_found);
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#endif /* ITERATOR_ITER_RESPTYPE_H */
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