message.h

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/*
 * Copyright (C) 2004-2010, 2012-2014  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2003  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id$ */

#ifndef DNS_MESSAGE_H
#define DNS_MESSAGE_H 1

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

#include <isc/lang.h>
#include <isc/magic.h>

#include <dns/compress.h>
#include <dns/masterdump.h>
#include <dns/types.h>

#include <dst/dst.h>

/*! \file dns/message.h
 * \brief Message Handling Module
 *
 * How this beast works:
 *
 * When a dns message is received in a buffer, dns_message_fromwire() is called
 * on the memory region.  Various items are checked including the format
 * of the message (if counts are right, if counts consume the entire sections,
 * and if sections consume the entire message) and known pseudo-RRs in the
 * additional data section are analyzed and removed.
 *
 * TSIG checking is also done at this layer, and any DNSSEC transaction
 * signatures should also be checked here.
 *
 * Notes on using the gettemp*() and puttemp*() functions:
 *
 * These functions return items (names, rdatasets, etc) allocated from some
 * internal state of the dns_message_t.
 *
 * Names and rdatasets must be put back into the dns_message_t in
 * one of two ways.  Assume a name was allocated via
 * dns_message_gettempname():
 *
 *\li   (1) insert it into a section, using dns_message_addname().
 *
 *\li   (2) return it to the message using dns_message_puttempname().
 *
 * The same applies to rdatasets.
 *
 * On the other hand, offsets, rdatalists and rdatas allocated using
 * dns_message_gettemp*() will always be freed automatically
 * when the message is reset or destroyed; calling dns_message_puttemp*()
 * on rdatalists and rdatas is optional and serves only to enable the item
 * to be reused multiple times during the lifetime of the message; offsets
 * cannot be reused.
 *
 * Buffers allocated using isc_buffer_allocate() can be automatically freed
 * as well by giving the buffer to the message using dns_message_takebuffer().
 * Doing this will cause the buffer to be freed using isc_buffer_free()
 * when the section lists are cleared, such as in a reset or in a destroy.
 * Since the buffer itself exists until the message is destroyed, this sort
 * of code can be written:
 *
 * \code
 *      buffer = isc_buffer_allocate(mctx, 512);
 *      name = NULL;
 *      name = dns_message_gettempname(message, &name);
 *      dns_name_init(name, NULL);
 *      result = dns_name_fromtext(name, &source, dns_rootname, 0, buffer);
 *      dns_message_takebuffer(message, &buffer);
 * \endcode
 *
 *
 * TODO:
 *
 * XXX Needed:  ways to set and retrieve EDNS information, add rdata to a
 * section, move rdata from one section to another, remove rdata, etc.
 */

#define DNS_MESSAGEFLAG_QR              0x8000U
#define DNS_MESSAGEFLAG_AA              0x0400U
#define DNS_MESSAGEFLAG_TC              0x0200U
#define DNS_MESSAGEFLAG_RD              0x0100U
#define DNS_MESSAGEFLAG_RA              0x0080U
#define DNS_MESSAGEFLAG_AD              0x0020U
#define DNS_MESSAGEFLAG_CD              0x0010U

/*%< EDNS0 extended message flags */
#define DNS_MESSAGEEXTFLAG_DO           0x8000U

/*%< EDNS0 extended OPT codes */
#define DNS_OPT_NSID            0x0003          /*%< NSID opt code */
#define DNS_OPT_CLIENT_SUBNET   0x0008          /*%< client subnet opt code */
#define DNS_OPT_EXPIRE          0x0009          /*%< EXPIRE opt code */

/*%< Experimental options [65001...65534] as per RFC6891 */
#define DNS_OPT_SIT             65001           /*%< SIT opt code */

/*%< The number of EDNS options we know about. */
#define DNS_EDNSOPTIONS 5

#define DNS_MESSAGE_REPLYPRESERVE       (DNS_MESSAGEFLAG_RD|DNS_MESSAGEFLAG_CD)
#define DNS_MESSAGEEXTFLAG_REPLYPRESERVE (DNS_MESSAGEEXTFLAG_DO)

#define DNS_MESSAGE_HEADERLEN           12 /*%< 6 isc_uint16_t's */

#define DNS_MESSAGE_MAGIC               ISC_MAGIC('M','S','G','@')
#define DNS_MESSAGE_VALID(msg)          ISC_MAGIC_VALID(msg, DNS_MESSAGE_MAGIC)

/*
 * Ordering here matters.  DNS_SECTION_ANY must be the lowest and negative,
 * and DNS_SECTION_MAX must be one greater than the last used section.
 */
typedef int dns_section_t;
#define DNS_SECTION_ANY                 (-1)
#define DNS_SECTION_QUESTION            0
#define DNS_SECTION_ANSWER              1
#define DNS_SECTION_AUTHORITY           2
#define DNS_SECTION_ADDITIONAL          3
#define DNS_SECTION_MAX                 4

typedef int dns_pseudosection_t;
#define DNS_PSEUDOSECTION_ANY           (-1)
#define DNS_PSEUDOSECTION_OPT           0
#define DNS_PSEUDOSECTION_TSIG          1
#define DNS_PSEUDOSECTION_SIG0          2
#define DNS_PSEUDOSECTION_MAX           3

typedef int dns_messagetextflag_t;
#define DNS_MESSAGETEXTFLAG_NOCOMMENTS  0x0001
#define DNS_MESSAGETEXTFLAG_NOHEADERS   0x0002
#define DNS_MESSAGETEXTFLAG_ONESOA      0x0004
#define DNS_MESSAGETEXTFLAG_OMITSOA     0x0008
#define DNS_MESSAGETEXTFLAG_COMMENTDATA 0x0010

/*
 * Dynamic update names for these sections.
 */
#define DNS_SECTION_ZONE                DNS_SECTION_QUESTION
#define DNS_SECTION_PREREQUISITE        DNS_SECTION_ANSWER
#define DNS_SECTION_UPDATE              DNS_SECTION_AUTHORITY

/*
 * These tell the message library how the created dns_message_t will be used.
 */
#define DNS_MESSAGE_INTENTUNKNOWN       0 /*%< internal use only */
#define DNS_MESSAGE_INTENTPARSE         1 /*%< parsing messages */
#define DNS_MESSAGE_INTENTRENDER        2 /*%< rendering */

/*
 * Control behavior of parsing
 */
#define DNS_MESSAGEPARSE_PRESERVEORDER  0x0001  /*%< preserve rdata order */
#define DNS_MESSAGEPARSE_BESTEFFORT     0x0002  /*%< return a message if a
                                                   recoverable parse error
                                                   occurs */
#define DNS_MESSAGEPARSE_CLONEBUFFER    0x0004  /*%< save a copy of the
                                                   source buffer */
#define DNS_MESSAGEPARSE_IGNORETRUNCATION 0x0008 /*%< truncation errors are
                                                  * not fatal. */

/*
 * Control behavior of rendering
 */
#define DNS_MESSAGERENDER_ORDERED       0x0001  /*%< don't change order */
#define DNS_MESSAGERENDER_PARTIAL       0x0002  /*%< allow a partial rdataset */
#define DNS_MESSAGERENDER_OMITDNSSEC    0x0004  /*%< omit DNSSEC records */
#define DNS_MESSAGERENDER_PREFER_A      0x0008  /*%< prefer A records in
                                                      additional section. */
#define DNS_MESSAGERENDER_PREFER_AAAA   0x0010  /*%< prefer AAAA records in
                                                  additional section. */
#ifdef ALLOW_FILTER_AAAA
#define DNS_MESSAGERENDER_FILTER_AAAA   0x0020  /*%< filter AAAA records */
#endif

typedef struct dns_msgblock dns_msgblock_t;

struct dns_message {
        /* public from here down */
        unsigned int                    magic;

        dns_messageid_t                 id;
        unsigned int                    flags;
        dns_rcode_t                     rcode;
        unsigned int                    opcode;
        dns_rdataclass_t                rdclass;

        /* 4 real, 1 pseudo */
        unsigned int                    counts[DNS_SECTION_MAX];

        /* private from here down */
        dns_namelist_t                  sections[DNS_SECTION_MAX];
        dns_name_t                     *cursors[DNS_SECTION_MAX];
        dns_rdataset_t                 *opt;
        dns_rdataset_t                 *sig0;
        dns_rdataset_t                 *tsig;

        int                             state;
        unsigned int                    from_to_wire : 2;
        unsigned int                    header_ok : 1;
        unsigned int                    question_ok : 1;
        unsigned int                    tcp_continuation : 1;
        unsigned int                    verified_sig : 1;
        unsigned int                    verify_attempted : 1;
        unsigned int                    free_query : 1;
        unsigned int                    free_saved : 1;
        unsigned int                    sitok : 1;
        unsigned int                    sitbad : 1;

        unsigned int                    opt_reserved;
        unsigned int                    sig_reserved;
        unsigned int                    reserved; /* reserved space (render) */

        isc_buffer_t                   *buffer;
        dns_compress_t                 *cctx;

        isc_mem_t                      *mctx;
        isc_mempool_t                  *namepool;
        isc_mempool_t                  *rdspool;

        isc_bufferlist_t                scratchpad;
        isc_bufferlist_t                cleanup;

        ISC_LIST(dns_msgblock_t)        rdatas;
        ISC_LIST(dns_msgblock_t)        rdatalists;
        ISC_LIST(dns_msgblock_t)        offsets;

        ISC_LIST(dns_rdata_t)           freerdata;
        ISC_LIST(dns_rdatalist_t)       freerdatalist;

        dns_rcode_t                     tsigstatus;
        dns_rcode_t                     querytsigstatus;
        dns_name_t                     *tsigname; /* Owner name of TSIG, if any */
        dns_rdataset_t                 *querytsig;
        dns_tsigkey_t                  *tsigkey;
        dst_context_t                  *tsigctx;
        int                             sigstart;
        int                             timeadjust;

        dns_name_t                     *sig0name; /* Owner name of SIG0, if any */
        dst_key_t                      *sig0key;
        dns_rcode_t                     sig0status;
        isc_region_t                    query;
        isc_region_t                    saved;

        dns_rdatasetorderfunc_t         order;
        const void *                    order_arg;
};

struct dns_ednsopt {
        isc_uint16_t                    code;
        isc_uint16_t                    length;
        unsigned char                   *value;
};

/***
 *** Functions
 ***/

ISC_LANG_BEGINDECLS

isc_result_t
dns_message_create(isc_mem_t *mctx, unsigned int intent, dns_message_t **msgp);

/*%<
 * Create msg structure.
 *
 * This function will allocate some internal blocks of memory that are
 * expected to be needed for parsing or rendering nearly any type of message.
 *
 * Requires:
 *\li   'mctx' be a valid memory context.
 *
 *\li   'msgp' be non-null and '*msg' be NULL.
 *
 *\li   'intent' must be one of DNS_MESSAGE_INTENTPARSE or
 *      #DNS_MESSAGE_INTENTRENDER.
 *
 * Ensures:
 *\li   The data in "*msg" is set to indicate an unused and empty msg
 *      structure.
 *
 * Returns:
 *\li   #ISC_R_NOMEMORY         -- out of memory
 *\li   #ISC_R_SUCCESS          -- success
 */

void
dns_message_reset(dns_message_t *msg, unsigned int intent);
/*%<
 * Reset a message structure to default state.  All internal lists are freed
 * or reset to a default state as well.  This is simply a more efficient
 * way to call dns_message_destroy() followed by dns_message_allocate(),
 * since it avoid many memory allocations.
 *
 * If any data loanouts (buffers, names, rdatas, etc) were requested,
 * the caller must no longer use them after this call.
 *
 * The intended next use of the message will be 'intent'.
 *
 * Requires:
 *
 *\li   'msg' be valid.
 *
 *\li   'intent' is DNS_MESSAGE_INTENTPARSE or DNS_MESSAGE_INTENTRENDER
 */

void
dns_message_destroy(dns_message_t **msgp);
/*%<
 * Destroy all state in the message.
 *
 * Requires:
 *
 *\li   'msgp' be valid.
 *
 * Ensures:
 *\li   '*msgp' == NULL
 */

isc_result_t
dns_message_sectiontotext(dns_message_t *msg, dns_section_t section,
                          const dns_master_style_t *style,
                          dns_messagetextflag_t flags,
                          isc_buffer_t *target);

isc_result_t
dns_message_pseudosectiontotext(dns_message_t *msg,
                                dns_pseudosection_t section,
                                const dns_master_style_t *style,
                                dns_messagetextflag_t flags,
                                isc_buffer_t *target);
/*%<
 * Convert section 'section' or 'pseudosection' of message 'msg' to
 * a cleartext representation
 *
 * Notes:
 *     \li See dns_message_totext for meanings of flags.
 *
 * Requires:
 *
 *\li   'msg' is a valid message.
 *
 *\li   'style' is a valid master dump style.
 *
 *\li   'target' is a valid buffer.
 *
 *\li   'section' is a valid section label.
 *
 * Ensures:
 *
 *\li   If the result is success:
 *              The used space in 'target' is updated.
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS
 *\li   #ISC_R_NOSPACE
 *\li   #ISC_R_NOMORE
 *
 *\li   Note: On error return, *target may be partially filled with data.
*/

isc_result_t
dns_message_totext(dns_message_t *msg, const dns_master_style_t *style,
                   dns_messagetextflag_t flags, isc_buffer_t *target);
/*%<
 * Convert all sections of message 'msg' to a cleartext representation
 *
 * Notes:
 * \li     In flags, If #DNS_MESSAGETEXTFLAG_OMITDOT is set, then the
 *      final '.' in absolute names will not be emitted.  If
 *      #DNS_MESSAGETEXTFLAG_NOCOMMENTS is cleared, lines beginning
 *      with ";;" will be emitted indicating section name.  If
 *      #DNS_MESSAGETEXTFLAG_NOHEADERS is cleared, header lines will
 *      be emitted.
 *
 *      If #DNS_MESSAGETEXTFLAG_ONESOA is set then only print the
 *      first SOA record in the answer section.  If
 *      #DNS_MESSAGETEXTFLAG_OMITSOA is set don't print any SOA records
 *      in the answer section.  These are useful for suppressing the
 *      display of the second SOA record in a AXFR by setting
 *      #DNS_MESSAGETEXTFLAG_ONESOA on the first message in a AXFR stream
 *      and #DNS_MESSAGETEXTFLAG_OMITSOA on subsequent messages.
 *
 * Requires:
 *
 *\li   'msg' is a valid message.
 *
 *\li   'style' is a valid master dump style.
 *
 *\li   'target' is a valid buffer.
 *
 * Ensures:
 *
 *\li   If the result is success:
 *              The used space in 'target' is updated.
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS
 *\li   #ISC_R_NOSPACE
 *\li   #ISC_R_NOMORE
 *
 *\li   Note: On error return, *target may be partially filled with data.
 */

isc_result_t
dns_message_parse(dns_message_t *msg, isc_buffer_t *source,
                  unsigned int options);
/*%<
 * Parse raw wire data in 'source' as a DNS message.
 *
 * OPT records are detected and stored in the pseudo-section "opt".
 * TSIGs are detected and stored in the pseudo-section "tsig".
 *
 * If #DNS_MESSAGEPARSE_PRESERVEORDER is set, or if the opcode of the message
 * is UPDATE, a separate dns_name_t object will be created for each RR in the
 * message.  Each such dns_name_t will have a single rdataset containing the
 * single RR, and the order of the RRs in the message is preserved.
 * Otherwise, only one dns_name_t object will be created for each unique
 * owner name in the section, and each such dns_name_t will have a list
 * of rdatasets.  To access the names and their data, use
 * dns_message_firstname() and dns_message_nextname().
 *
 * If #DNS_MESSAGEPARSE_BESTEFFORT is set, errors in message content will
 * not be considered FORMERRs.  If the entire message can be parsed, it
 * will be returned and DNS_R_RECOVERABLE will be returned.
 *
 * If #DNS_MESSAGEPARSE_IGNORETRUNCATION is set then return as many complete
 * RR's as possible, DNS_R_RECOVERABLE will be returned.
 *
 * OPT and TSIG records are always handled specially, regardless of the
 * 'preserve_order' setting.
 *
 * Requires:
 *\li   "msg" be valid.
 *
 *\li   "buffer" be a wire format buffer.
 *
 * Ensures:
 *\li   The buffer's data format is correct.
 *
 *\li   The buffer's contents verify as correct regarding header bits, buffer
 *      and rdata sizes, etc.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all is well
 *\li   #ISC_R_NOMEMORY         -- no memory
 *\li   #DNS_R_RECOVERABLE      -- the message parsed properly, but contained
 *                                 errors.
 *\li   Many other errors possible XXXMLG
 */

isc_result_t
dns_message_renderbegin(dns_message_t *msg, dns_compress_t *cctx,
                        isc_buffer_t *buffer);
/*%<
 * Begin rendering on a message.  Only one call can be made to this function
 * per message.
 *
 * The compression context is "owned" by the message library until
 * dns_message_renderend() is called.  It must be invalidated by the caller.
 *
 * The buffer is "owned" by the message library until dns_message_renderend()
 * is called.
 *
 * Requires:
 *
 *\li   'msg' be valid.
 *
 *\li   'cctx' be valid.
 *
 *\li   'buffer' is a valid buffer.
 *
 * Side Effects:
 *
 *\li   The buffer is cleared before it is used.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all is well
 *\li   #ISC_R_NOSPACE          -- output buffer is too small
 */

isc_result_t
dns_message_renderchangebuffer(dns_message_t *msg, isc_buffer_t *buffer);
/*%<
 * Reset the buffer.  This can be used after growing the old buffer
 * on a ISC_R_NOSPACE return from most of the render functions.
 *
 * On successful completion, the old buffer is no longer used by the
 * library.  The new buffer is owned by the library until
 * dns_message_renderend() is called.
 *
 * Requires:
 *
 *\li   'msg' be valid.
 *
 *\li   dns_message_renderbegin() was called.
 *
 *\li   buffer != NULL.
 *
 * Returns:
 *\li   #ISC_R_NOSPACE          -- new buffer is too small
 *\li   #ISC_R_SUCCESS          -- all is well.
 */

isc_result_t
dns_message_renderreserve(dns_message_t *msg, unsigned int space);
/*%<
 * XXXMLG should use size_t rather than unsigned int once the buffer
 * API is cleaned up
 *
 * Reserve "space" bytes in the given buffer.
 *
 * Requires:
 *
 *\li   'msg' be valid.
 *
 *\li   dns_message_renderbegin() was called.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all is well.
 *\li   #ISC_R_NOSPACE          -- not enough free space in the buffer.
 */

void
dns_message_renderrelease(dns_message_t *msg, unsigned int space);
/*%<
 * XXXMLG should use size_t rather than unsigned int once the buffer
 * API is cleaned up
 *
 * Release "space" bytes in the given buffer that was previously reserved.
 *
 * Requires:
 *
 *\li   'msg' be valid.
 *
 *\li   'space' is less than or equal to the total amount of space reserved
 *      via prior calls to dns_message_renderreserve().
 *
 *\li   dns_message_renderbegin() was called.
 */

isc_result_t
dns_message_rendersection(dns_message_t *msg, dns_section_t section,
                          unsigned int options);
/*%<
 * Render all names, rdatalists, etc from the given section at the
 * specified priority or higher.
 *
 * Requires:
 *\li   'msg' be valid.
 *
 *\li   'section' be a valid section.
 *
 *\li   dns_message_renderbegin() was called.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all records were written, and there are
 *                                 no more records for this section.
 *\li   #ISC_R_NOSPACE          -- Not enough room in the buffer to write
 *                                 all records requested.
 *\li   #DNS_R_MOREDATA         -- All requested records written, and there
 *                                 are records remaining for this section.
 */

void
dns_message_renderheader(dns_message_t *msg, isc_buffer_t *target);
/*%<
 * Render the message header.  This is implicitly called by
 * dns_message_renderend().
 *
 * Requires:
 *
 *\li   'msg' be a valid message.
 *
 *\li   dns_message_renderbegin() was called.
 *
 *\li   'target' is a valid buffer with enough space to hold a message header
 */

isc_result_t
dns_message_renderend(dns_message_t *msg);
/*%<
 * Finish rendering to the buffer.  Note that more data can be in the
 * 'msg' structure.  Destroying the structure will free this, or in a multi-
 * part EDNS1 message this data can be rendered to another buffer later.
 *
 * Requires:
 *
 *\li   'msg' be a valid message.
 *
 *\li   dns_message_renderbegin() was called.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all is well.
 */

void
dns_message_renderreset(dns_message_t *msg);
/*%<
 * Reset the message so that it may be rendered again.
 *
 * Notes:
 *
 *\li   If dns_message_renderbegin() has been called, dns_message_renderend()
 *      must be called before calling this function.
 *
 * Requires:
 *
 *\li   'msg' be a valid message with rendering intent.
 */

isc_result_t
dns_message_firstname(dns_message_t *msg, dns_section_t section);
/*%<
 * Set internal per-section name pointer to the beginning of the section.
 *
 * The functions dns_message_firstname() and dns_message_nextname() may
 * be used for iterating over the owner names in a section.
 *
 * Requires:
 *
 *\li           'msg' be valid.
 *
 *\li   'section' be a valid section.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- All is well.
 *\li   #ISC_R_NOMORE           -- No names on given section.
 */

isc_result_t
dns_message_nextname(dns_message_t *msg, dns_section_t section);
/*%<
 * Sets the internal per-section name pointer to point to the next name
 * in that section.
 *
 * Requires:
 *
 * \li          'msg' be valid.
 *
 *\li   'section' be a valid section.
 *
 *\li   dns_message_firstname() must have been called on this section,
 *      and the result was ISC_R_SUCCESS.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- All is well.
 *\li   #ISC_R_NOMORE           -- No more names in given section.
 */

void
dns_message_currentname(dns_message_t *msg, dns_section_t section,
                        dns_name_t **name);
/*%<
 * Sets 'name' to point to the name where the per-section internal name
 * pointer is currently set.
 *
 * This function returns the name in the database, so any data associated
 * with it (via the name's "list" member) contains the actual rdatasets.
 *
 * Requires:
 *
 *\li   'msg' be valid.
 *
 *\li   'name' be non-NULL, and *name be NULL.
 *
 *\li   'section' be a valid section.
 *
 *\li   dns_message_firstname() must have been called on this section,
 *      and the result of it and any dns_message_nextname() calls was
 *      #ISC_R_SUCCESS.
 */

isc_result_t
dns_message_findname(dns_message_t *msg, dns_section_t section,
                     dns_name_t *target, dns_rdatatype_t type,
                     dns_rdatatype_t covers, dns_name_t **foundname,
                     dns_rdataset_t **rdataset);
/*%<
 * Search for a name in the specified section.  If it is found, *name is
 * set to point to the name, and *rdataset is set to point to the found
 * rdataset (if type is specified as other than dns_rdatatype_any).
 *
 * Requires:
 *\li   'msg' be valid.
 *
 *\li   'section' be a valid section.
 *
 *\li   If a pointer to the name is desired, 'foundname' should be non-NULL.
 *      If it is non-NULL, '*foundname' MUST be NULL.
 *
 *\li   If a type other than dns_datatype_any is searched for, 'rdataset'
 *      may be non-NULL, '*rdataset' be NULL, and will point at the found
 *      rdataset.  If the type is dns_datatype_any, 'rdataset' must be NULL.
 *
 *\li   'target' be a valid name.
 *
 *\li   'type' be a valid type.
 *
 *\li   If 'type' is dns_rdatatype_rrsig, 'covers' must be a valid type.
 *      Otherwise it should be 0.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all is well.
 *\li   #DNS_R_NXDOMAIN         -- name does not exist in that section.
 *\li   #DNS_R_NXRRSET          -- The name does exist, but the desired
 *                                 type does not.
 */

isc_result_t
dns_message_findtype(dns_name_t *name, dns_rdatatype_t type,
                     dns_rdatatype_t covers, dns_rdataset_t **rdataset);
/*%<
 * Search the name for the specified type.  If it is found, *rdataset is
 * filled in with a pointer to that rdataset.
 *
 * Requires:
 *\li   if '**rdataset' is non-NULL, *rdataset needs to be NULL.
 *
 *\li   'type' be a valid type, and NOT dns_rdatatype_any.
 *
 *\li   If 'type' is dns_rdatatype_rrsig, 'covers' must be a valid type.
 *      Otherwise it should be 0.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all is well.
 *\li   #ISC_R_NOTFOUND         -- the desired type does not exist.
 */

isc_result_t
dns_message_find(dns_name_t *name, dns_rdataclass_t rdclass,
                 dns_rdatatype_t type, dns_rdatatype_t covers,
                 dns_rdataset_t **rdataset);
/*%<
 * Search the name for the specified rdclass and type.  If it is found,
 * *rdataset is filled in with a pointer to that rdataset.
 *
 * Requires:
 *\li   if '**rdataset' is non-NULL, *rdataset needs to be NULL.
 *
 *\li   'type' be a valid type, and NOT dns_rdatatype_any.
 *
 *\li   If 'type' is dns_rdatatype_rrsig, 'covers' must be a valid type.
 *      Otherwise it should be 0.
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- all is well.
 *\li   #ISC_R_NOTFOUND         -- the desired type does not exist.
 */

void
dns_message_movename(dns_message_t *msg, dns_name_t *name,
                     dns_section_t fromsection,
                     dns_section_t tosection);
/*%<
 * Move a name from one section to another.
 *
 * Requires:
 *
 *\li   'msg' be valid.
 *
 *\li   'name' must be a name already in 'fromsection'.
 *
 *\li   'fromsection' must be a valid section.
 *
 *\li   'tosection' must be a valid section.
 */

void
dns_message_addname(dns_message_t *msg, dns_name_t *name,
                    dns_section_t section);
/*%<
 * Adds the name to the given section.
 *
 * It is the caller's responsibility to enforce any unique name requirements
 * in a section.
 *
 * Requires:
 *
 *\li   'msg' be valid, and be a renderable message.
 *
 *\li   'name' be a valid absolute name.
 *
 *\li   'section' be a named section.
 */

void
dns_message_removename(dns_message_t *msg, dns_name_t *name,
                       dns_section_t section);
/*%<
 * Remove a existing name from a given section.
 *
 * It is the caller's responsibility to ensure the name is part of the
 * given section.
 *
 * Requires:
 *
 *\li   'msg' be valid, and be a renderable message.
 *
 *\li   'name' be a valid absolute name.
 *
 *\li   'section' be a named section.
 */


/*
 * LOANOUT FUNCTIONS
 *
 * Each of these functions loan a particular type of data to the caller.
 * The storage for these will vanish when the message is destroyed or
 * reset, and must NOT be used after these operations.
 */

isc_result_t
dns_message_gettempname(dns_message_t *msg, dns_name_t **item);
/*%<
 * Return a name that can be used for any temporary purpose, including
 * inserting into the message's linked lists.  The name must be returned
 * to the message code using dns_message_puttempname() or inserted into
 * one of the message's sections before the message is destroyed.
 *
 * It is the caller's responsibility to initialize this name.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item == NULL
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- All is well.
 *\li   #ISC_R_NOMEMORY         -- No item can be allocated.
 */

isc_result_t
dns_message_gettempoffsets(dns_message_t *msg, dns_offsets_t **item);
/*%<
 * Return an offsets array that can be used for any temporary purpose,
 * such as attaching to a temporary name.  The offsets will be freed
 * when the message is destroyed or reset.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item == NULL
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- All is well.
 *\li   #ISC_R_NOMEMORY         -- No item can be allocated.
 */

isc_result_t
dns_message_gettemprdata(dns_message_t *msg, dns_rdata_t **item);
/*%<
 * Return a rdata that can be used for any temporary purpose, including
 * inserting into the message's linked lists.  The rdata will be freed
 * when the message is destroyed or reset.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item == NULL
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- All is well.
 *\li   #ISC_R_NOMEMORY         -- No item can be allocated.
 */

isc_result_t
dns_message_gettemprdataset(dns_message_t *msg, dns_rdataset_t **item);
/*%<
 * Return a rdataset that can be used for any temporary purpose, including
 * inserting into the message's linked lists. The name must be returned
 * to the message code using dns_message_puttempname() or inserted into
 * one of the message's sections before the message is destroyed.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item == NULL
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- All is well.
 *\li   #ISC_R_NOMEMORY         -- No item can be allocated.
 */

isc_result_t
dns_message_gettemprdatalist(dns_message_t *msg, dns_rdatalist_t **item);
/*%<
 * Return a rdatalist that can be used for any temporary purpose, including
 * inserting into the message's linked lists.  The rdatalist will be
 * destroyed when the message is destroyed or reset.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item == NULL
 *
 * Returns:
 *\li   #ISC_R_SUCCESS          -- All is well.
 *\li   #ISC_R_NOMEMORY         -- No item can be allocated.
 */

void
dns_message_puttempname(dns_message_t *msg, dns_name_t **item);
/*%<
 * Return a borrowed name to the message's name free list.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item point to a name returned by
 *      dns_message_gettempname()
 *
 * Ensures:
 *\li   *item == NULL
 */

void
dns_message_puttemprdata(dns_message_t *msg, dns_rdata_t **item);
/*%<
 * Return a borrowed rdata to the message's rdata free list.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item point to a rdata returned by
 *      dns_message_gettemprdata()
 *
 * Ensures:
 *\li   *item == NULL
 */

void
dns_message_puttemprdataset(dns_message_t *msg, dns_rdataset_t **item);
/*%<
 * Return a borrowed rdataset to the message's rdataset free list.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item point to a rdataset returned by
 *      dns_message_gettemprdataset()
 *
 * Ensures:
 *\li   *item == NULL
 */

void
dns_message_puttemprdatalist(dns_message_t *msg, dns_rdatalist_t **item);
/*%<
 * Return a borrowed rdatalist to the message's rdatalist free list.
 *
 * Requires:
 *\li   msg be a valid message
 *
 *\li   item != NULL && *item point to a rdatalist returned by
 *      dns_message_gettemprdatalist()
 *
 * Ensures:
 *\li   *item == NULL
 */

isc_result_t
dns_message_peekheader(isc_buffer_t *source, dns_messageid_t *idp,
                       unsigned int *flagsp);
/*%<
 * Assume the remaining region of "source" is a DNS message.  Peek into
 * it and fill in "*idp" with the message id, and "*flagsp" with the flags.
 *
 * Requires:
 *
 *\li   source != NULL
 *
 * Ensures:
 *
 *\li   if (idp != NULL) *idp == message id.
 *
 *\li   if (flagsp != NULL) *flagsp == message flags.
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          -- all is well.
 *
 *\li   #ISC_R_UNEXPECTEDEND    -- buffer doesn't contain enough for a header.
 */

isc_result_t
dns_message_reply(dns_message_t *msg, isc_boolean_t want_question_section);
/*%<
 * Start formatting a reply to the query in 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message with parsing intent, and contains a query.
 *
 * Ensures:
 *
 *\li   The message will have a rendering intent.  If 'want_question_section'
 *      is true, the message opcode is query or notify, and the question
 *      section is present and properly formatted, then the question section
 *      will be included in the reply.  All other sections will be cleared.
 *      The QR flag will be set, the RD flag will be preserved, and all other
 *      flags will be cleared.
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          -- all is well.
 *
 *\li   #DNS_R_FORMERR          -- the header or question section of the
 *                                 message is invalid, replying is impossible.
 *                                 If DNS_R_FORMERR is returned when
 *                                 want_question_section is ISC_FALSE, then
 *                                 it's the header section that's bad;
 *                                 otherwise either of the header or question
 *                                 sections may be bad.
 */

dns_rdataset_t *
dns_message_getopt(dns_message_t *msg);
/*%<
 * Get the OPT record for 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message.
 *
 * Returns:
 *
 *\li   The OPT rdataset of 'msg', or NULL if there isn't one.
 */

isc_result_t
dns_message_setopt(dns_message_t *msg, dns_rdataset_t *opt);
/*%<
 * Set the OPT record for 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message with rendering intent
 *      and no sections have been rendered.
 *
 *\li   'opt' is a valid OPT record.
 *
 * Ensures:
 *
 *\li   The OPT record has either been freed or ownership of it has
 *      been transferred to the message.
 *
 *\li   If ISC_R_SUCCESS was returned, the OPT record will be rendered
 *      when dns_message_renderend() is called.
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          -- all is well.
 *
 *\li   #ISC_R_NOSPACE          -- there is no space for the OPT record.
 */

dns_rdataset_t *
dns_message_gettsig(dns_message_t *msg, dns_name_t **owner);
/*%<
 * Get the TSIG record and owner for 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message.
 *\li   'owner' is NULL or *owner is NULL.
 *
 * Returns:
 *
 *\li   The TSIG rdataset of 'msg', or NULL if there isn't one.
 *
 * Ensures:
 *
 * \li  If 'owner' is not NULL, it will point to the owner name.
 */

isc_result_t
dns_message_settsigkey(dns_message_t *msg, dns_tsigkey_t *key);
/*%<
 * Set the tsig key for 'msg'.  This is only necessary for when rendering a
 * query or parsing a response.  The key (if non-NULL) is attached to, and
 * will be detached when the message is destroyed.
 *
 * Requires:
 *
 *\li   'msg' is a valid message with rendering intent,
 *      dns_message_renderbegin() has been called, and no sections have been
 *      rendered.
 *\li   'key' is a valid tsig key or NULL.
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          -- all is well.
 *
 *\li   #ISC_R_NOSPACE          -- there is no space for the TSIG record.
 */

dns_tsigkey_t *
dns_message_gettsigkey(dns_message_t *msg);
/*%<
 * Gets the tsig key for 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message
 */

isc_result_t
dns_message_setquerytsig(dns_message_t *msg, isc_buffer_t *querytsig);
/*%<
 * Indicates that 'querytsig' is the TSIG from the signed query for which
 * 'msg' is the response.  This is also used for chained TSIGs in TCP
 * responses.
 *
 * Requires:
 *
 *\li   'querytsig' is a valid buffer as returned by dns_message_getquerytsig()
 *      or NULL
 *
 *\li   'msg' is a valid message
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS
 *\li   #ISC_R_NOMEMORY
 */

isc_result_t
dns_message_getquerytsig(dns_message_t *msg, isc_mem_t *mctx,
                         isc_buffer_t **querytsig);
/*%<
 * Gets the tsig from the TSIG from the signed query 'msg'.  This is also used
 * for chained TSIGs in TCP responses.  Unlike dns_message_gettsig, this makes
 * a copy of the data, so can be used if the message is destroyed.
 *
 * Requires:
 *
 *\li   'msg' is a valid signed message
 *\li   'mctx' is a valid memory context
 *\li   querytsig != NULL && *querytsig == NULL
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS
 *\li   #ISC_R_NOMEMORY
 *
 * Ensures:
 *\li   'tsig' points to NULL or an allocated buffer which must be freed
 *      by the caller.
 */

dns_rdataset_t *
dns_message_getsig0(dns_message_t *msg, dns_name_t **owner);
/*%<
 * Get the SIG(0) record and owner for 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message.
 *\li   'owner' is NULL or *owner is NULL.
 *
 * Returns:
 *
 *\li   The SIG(0) rdataset of 'msg', or NULL if there isn't one.
 *
 * Ensures:
 *
 * \li  If 'owner' is not NULL, it will point to the owner name.
 */

isc_result_t
dns_message_setsig0key(dns_message_t *msg, dst_key_t *key);
/*%<
 * Set the SIG(0) key for 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message with rendering intent,
 *      dns_message_renderbegin() has been called, and no sections have been
 *      rendered.
 *\li   'key' is a valid sig key or NULL.
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          -- all is well.
 *
 *\li   #ISC_R_NOSPACE          -- there is no space for the SIG(0) record.
 */

dst_key_t *
dns_message_getsig0key(dns_message_t *msg);
/*%<
 * Gets the SIG(0) key for 'msg'.
 *
 * Requires:
 *
 *\li   'msg' is a valid message
 */

void
dns_message_takebuffer(dns_message_t *msg, isc_buffer_t **buffer);
/*%<
 * Give the *buffer to the message code to clean up when it is no
 * longer needed.  This is usually when the message is reset or
 * destroyed.
 *
 * Requires:
 *
 *\li   msg be a valid message.
 *
 *\li   buffer != NULL && *buffer is a valid isc_buffer_t, which was
 *      dynamically allocated via isc_buffer_allocate().
 */

isc_result_t
dns_message_signer(dns_message_t *msg, dns_name_t *signer);
/*%<
 * If this message was signed, return the identity of the signer.
 * Unless ISC_R_NOTFOUND is returned, signer will reflect the name of the
 * key that signed the message.
 *
 * Requires:
 *
 *\li   msg is a valid parsed message.
 *\li   signer is a valid name
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          - the message was signed, and *signer
 *                                contains the signing identity
 *
 *\li   #ISC_R_NOTFOUND         - no TSIG or SIG(0) record is present in the
 *                                message
 *
 *\li   #DNS_R_TSIGVERIFYFAILURE        - the message was signed by a TSIG, but the
 *                                signature failed to verify
 *
 *\li   #DNS_R_TSIGERRORSET     - the message was signed by a TSIG and
 *                                verified, but the query was rejected by
 *                                the server
 *
 *\li   #DNS_R_NOIDENTITY       - the message was signed by a TSIG and
 *                                verified, but the key has no identity since
 *                                it was generated by an unsigned TKEY process
 *
 *\li   #DNS_R_SIGINVALID       - the message was signed by a SIG(0), but
 *                                the signature failed to verify
 *
 *\li   #DNS_R_NOTVERIFIEDYET   - the message was signed by a TSIG or SIG(0),
 *                                but the signature has not been verified yet
 */

isc_result_t
dns_message_checksig(dns_message_t *msg, dns_view_t *view);
/*%<
 * If this message was signed, verify the signature.
 *
 * Requires:
 *
 *\li   msg is a valid parsed message.
 *\li   view is a valid view or NULL
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          - the message was unsigned, or the message
 *                                was signed correctly.
 *
 *\li   #DNS_R_EXPECTEDTSIG     - A TSIG was expected, but not seen
 *\li   #DNS_R_UNEXPECTEDTSIG   - A TSIG was seen but not expected
 *\li   #DNS_R_TSIGVERIFYFAILURE - The TSIG failed to verify
 */

isc_result_t
dns_message_rechecksig(dns_message_t *msg, dns_view_t *view);
/*%<
 * Reset the signature state and then if the message was signed,
 * verify the message.
 *
 * Requires:
 *
 *\li   msg is a valid parsed message.
 *\li   view is a valid view or NULL
 *
 * Returns:
 *
 *\li   #ISC_R_SUCCESS          - the message was unsigned, or the message
 *                                was signed correctly.
 *
 *\li   #DNS_R_EXPECTEDTSIG     - A TSIG was expected, but not seen
 *\li   #DNS_R_UNEXPECTEDTSIG   - A TSIG was seen but not expected
 *\li   #DNS_R_TSIGVERIFYFAILURE - The TSIG failed to verify
 */

void
dns_message_resetsig(dns_message_t *msg);
/*%<
 * Reset the signature state.
 *
 * Requires:
 *\li   'msg' is a valid parsed message.
 */

isc_region_t *
dns_message_getrawmessage(dns_message_t *msg);
/*%<
 * Retrieve the raw message in compressed wire format.  The message must
 * have been successfully parsed for it to have been saved.
 *
 * Requires:
 *\li   msg is a valid parsed message.
 *
 * Returns:
 *\li   NULL    if there is no saved message.
 *      a pointer to a region which refers the dns message.
 */

void
dns_message_setsortorder(dns_message_t *msg, dns_rdatasetorderfunc_t order,
                         const void *order_arg);
/*%<
 * Define the order in which RR sets get rendered by
 * dns_message_rendersection() to be the ascending order
 * defined by the integer value returned by 'order' when
 * given each RR and 'arg' as arguments.  If 'order' and
 * 'order_arg' are NULL, a default order is used.
 *
 * Requires:
 *\li   msg be a valid message.
 *\li   order_arg is NULL if and only if order is NULL.
 */

void
dns_message_settimeadjust(dns_message_t *msg, int timeadjust);
/*%<
 * Adjust the time used to sign/verify a message by timeadjust.
 * Currently only TSIG.
 *
 * Requires:
 *\li   msg be a valid message.
 */

int
dns_message_gettimeadjust(dns_message_t *msg);
/*%<
 * Return the current time adjustment.
 *
 * Requires:
 *\li   msg be a valid message.
 */

void
dns_message_logpacket(dns_message_t *message, const char *description,
                      isc_logcategory_t *category, isc_logmodule_t *module,
                      int level, isc_mem_t *mctx);
void
dns_message_logpacket2(dns_message_t *message,
                       const char *description, isc_sockaddr_t *address,
                       isc_logcategory_t *category, isc_logmodule_t *module,
                       int level, isc_mem_t *mctx);
void
dns_message_logfmtpacket(dns_message_t *message, const char *description,
                         isc_logcategory_t *category, isc_logmodule_t *module,
                         const dns_master_style_t *style, int level,
                         isc_mem_t *mctx);
void
dns_message_logfmtpacket2(dns_message_t *message,
                          const char *description, isc_sockaddr_t *address,
                          isc_logcategory_t *category, isc_logmodule_t *module,
                          const dns_master_style_t *style, int level,
                          isc_mem_t *mctx);
/*%<
 * Log 'message' at the specified logging parameters.
 *
 * For dns_message_logpacket and dns_message_logfmtpacket expect the
 * 'description' to end in a newline.
 *
 * For dns_message_logpacket2 and dns_message_logfmtpacket2
 * 'description' will be emitted at the start of the message followed
 * by the formatted address and a newline.
 *
 * Requires:
 * \li   message be a valid.
 * \li   description to be non NULL.
 * \li   address to be non NULL.
 * \li   category to be valid.
 * \li   module to be valid.
 * \li   style to be valid.
 * \li   mctx to be a valid.
 */

isc_result_t
dns_message_buildopt(dns_message_t *msg, dns_rdataset_t **opt,
                     unsigned int version, isc_uint16_t udpsize,
                     unsigned int flags, dns_ednsopt_t *ednsopts, size_t count);
/*%<
 * Built a opt record.
 *
 * Requires:
 * \li   msg be a valid message.
 * \li   opt to be a non NULL and *opt to be NULL.
 *
 * Returns:
 * \li   ISC_R_SUCCESS on success.
 * \li   ISC_R_NOMEMORY
 * \li   ISC_R_NOSPACE
 * \li   other.
 */

ISC_LANG_ENDDECLS

#endif /* DNS_MESSAGE_H */

---