IO-APIC
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 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

#ifndef DNS_NAME_H
#define DNS_NAME_H 1

/*****
***** Module Info
*****/

/*! \file dns/name.h
 * \brief
 * Provides facilities for manipulating DNS names and labels, including
 * conversions to and from wire format and text format.
 *
 * Given the large number of names possible in a nameserver, and because
 * names occur in rdata, it was important to come up with a very efficient
 * way of storing name data, but at the same time allow names to be
 * manipulated.  The decision was to store names in uncompressed wire format,
 * and not to make them fully abstracted objects; i.e. certain parts of the
 * server know names are stored that way.  This saves a lot of memory, and
 * makes adding names to messages easy.  Having much of the server know
 * the representation would be perilous, and we certainly don't want each
 * user of names to be manipulating such a low-level structure.  This is
 * where the Names and Labels module comes in.  The module allows name or
 * label handles to be created and attached to uncompressed wire format
 * regions.  All name operations and conversions are done through these
 * handles.
 *
 * MP:
 *\li	Clients of this module must impose any required synchronization.
 *
 * Reliability:
 *\li	This module deals with low-level byte streams.  Errors in any of
 *	the functions are likely to crash the server or corrupt memory.
 *
 * Resources:
 *\li	None.
 *
 * Security:
 *
 *\li	*** WARNING ***
 *
 *\li	dns_name_fromwire() deals with raw network data.  An error in
 *	this routine could result in the failure or hijacking of the server.
 *
 * Standards:
 *\li	RFC1035
 *\li	Draft EDNS0 (0)
 *\li	Draft Binary Labels (2)
 *
 */

/***
 *** Imports
 ***/

#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>

#include <isc/ht.h>
#include <isc/lang.h>
#include <isc/magic.h>
#include <isc/region.h> /* Required for storage size of dns_label_t. */

#include <dns/types.h>

ISC_LANG_BEGINDECLS

/*****
***** Labels
*****
***** A 'label' is basically a region.  It contains one DNS wire format
***** label of type 00 (ordinary).
*****/

/*****
***** Names
*****
***** A 'name' is a handle to a binary region.  It contains a sequence of one
***** or more DNS wire format labels of type 00 (ordinary).
***** Note that all names are not required to end with the root label,
***** as they are in the actual DNS wire protocol.
*****/

/***
 *** Types
 ***/

/*%
 * Clients are strongly discouraged from using this type directly,  with
 * the exception of the 'link' and 'list' fields which may be used directly
 * for whatever purpose the client desires.
 */
struct dns_name {
	unsigned int   magic;
	unsigned char *ndata;
	unsigned int   length;
	unsigned int   labels;
	unsigned int   attributes;
	unsigned char *offsets;
	isc_buffer_t  *buffer;
	ISC_LINK(dns_name_t) link;
	ISC_LIST(dns_rdataset_t) list;
	isc_ht_t *ht;
};

#define DNS_NAME_MAGIC ISC_MAGIC('D', 'N', 'S', 'n')

#define DNS_NAMEATTR_ABSOLUTE	0x00000001
#define DNS_NAMEATTR_READONLY	0x00000002
#define DNS_NAMEATTR_DYNAMIC	0x00000004
#define DNS_NAMEATTR_DYNOFFSETS 0x00000008
#define DNS_NAMEATTR_NOCOMPRESS 0x00000010
/*
 * Attributes below 0x0100 reserved for name.c usage.
 */
#define DNS_NAMEATTR_CACHE	  0x00000100 /*%< Used by resolver. */
#define DNS_NAMEATTR_ANSWER	  0x00000200 /*%< Used by resolver. */
#define DNS_NAMEATTR_NCACHE	  0x00000400 /*%< Used by resolver. */
#define DNS_NAMEATTR_CHAINING	  0x00000800 /*%< Used by resolver. */
#define DNS_NAMEATTR_CHASE	  0x00001000 /*%< Used by resolver. */
#define DNS_NAMEATTR_WILDCARD	  0x00002000 /*%< Used by server. */
#define DNS_NAMEATTR_PREREQUISITE 0x0000400