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