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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_DB_H
#define DNS_DB_H 1
/*****
***** Module Info
*****/
/*! \file dns/db.h
* \brief
* The DNS DB interface allows named rdatasets to be stored and retrieved.
*
* The dns_db_t type is like a "virtual class". To actually use
* DBs, an implementation of the class is required.
*
* XXX more XXX
*
* MP:
* \li The module ensures appropriate synchronization of data structures it
* creates and manipulates.
*
* Reliability:
* \li No anticipated impact.
*
* Resources:
* \li TBS
*
* Security:
* \li No anticipated impact.
*
* Standards:
* \li None.
*/
/*****
***** Imports
*****/
#include <inttypes.h>
#include <stdbool.h>
#include <isc/deprecated.h>
#include <isc/lang.h>
#include <isc/magic.h>
#include <isc/ondestroy.h>
#include <isc/stats.h>
#include <isc/stdtime.h>
#include <dns/clientinfo.h>
#include <dns/fixedname.h>
#include <dns/name.h>
#include <dns/rdata.h>
#include <dns/rdataset.h>
#include <dns/rpz.h>
#include <dns/types.h>
ISC_LANG_BEGINDECLS
/*****
***** Types
*****/
typedef struct dns_dbmethods {
void (*attach)(dns_db_t *source, dns_db_t **targetp);
void (*detach)(dns_db_t **dbp);
isc_result_t (*beginload)(dns_db_t *db,
dns_rdatacallbacks_t *callbacks);
isc_result_t (*endload)(dns_db_t *db,
dns_rdatacallbacks_t *callbacks);
isc_result_t (*serialize)(dns_db_t *db,
dns_dbversion_t *version, FILE *file);
isc_result_t (*dump)(dns_db_t *db, dns_dbversion_t *version,
const char *filename,
dns_masterformat_t masterformat);
void (*currentversion)(dns_db_t *db,
dns_dbversion_t **versionp);
isc_result_t (*newversion)(dns_db_t *db,
dns_dbversion_t **versionp);
void (*attachversion)(dns_db_t *db, dns_dbversion_t *source,
dns_dbversion_t **targetp);
void (*closeversion)(dns_db_t *db,
dns_dbversion_t **versionp,
bool commit);
isc_result_t (*findnode)(dns_db_t *db, dns_name_t *name,
bool create,
dns_dbnode_t **nodep);
isc_result_t (*find)(dns_db_t *db, dns_name_t *name,
dns_dbversion_t *version,
dns_rdatatype_t type, unsigned int options,
isc_stdtime_t now,
dns_dbnode_t **nodep, dns_name_t *foundname,
dns_rdataset_t *rdataset,
dns_rdataset_t *sigrdataset);
isc_result_t (*findzonecut)(dns_db_t *db, dns_name_t *name,
unsigned int options, isc_stdtime_t now,
dns_dbnode_t **nodep,
dns_name_t *foundname,
dns_rdataset_t *rdataset,
dns_rdataset_t *sigrdataset);
void (*attachnode)(dns_db_t *db,
dns_dbnode_t *source,
dns_dbnode_t **targetp);
void (*detachnode)(dns_db_t *db,
dns_dbnode_t **targetp);
isc_result_t (*expirenode)(dns_db_t *db, dns_dbnode_t *node,
isc_stdtime_t now);
void (*printnode)(dns_db_t *db, dns_dbnode_t *node,
FILE *out);
isc_result_t (*createiterator)(dns_db_t *db, unsigned int options,
dns_dbiterator_t **iteratorp);
isc_result_t (*findrdataset)(dns_db_t *db, dns_dbnode_t *node,
dns_dbversion_t *version,
dns_rdatatype_t type,
dns_rdatatype_t covers,
isc_stdtime_t now,
dns_rdataset_t *rdataset,
dns_rdataset_t *sigrdataset);
isc_result_t (*allrdatasets)(dns_db_t *db, dns_dbnode_t *node,
dns_dbversion_t *version,
isc_stdtime_t now,
dns_rdatasetiter_t **iteratorp);
isc_result_t (*addrdataset)(dns_db_t *db, dns_dbnode_t *node,
dns_dbversion_t *version,
isc_stdtime_t now,
dns_rdataset_t *rdataset,
unsigned int options,
dns_rdataset_t *addedrdataset);
isc_result_t (*subtractrdataset)(dns_db_t *db, dns_dbnode_t *node,
dns_dbversion_t *version,
dns_rdataset_t *rdataset,
unsigned int options,
dns_rdataset_t *newrdataset);
isc_result_t (*deleterdataset)(dns_db_t *db, dns_dbnode_t *node,
dns_dbversion_t *version,
dns_rdatatype_t type,
dns_rdatatype_t covers);
bool (*issecure)(dns_db_t *db);
unsigned int (*nodecount)(dns_db_t *db);
bool (*ispersistent)(dns_db_t *db);
void (*overmem)(dns_db_t *db, bool overmem);
void (*settask)(dns_db_t *db, isc_task_t *);
isc_result_t (*getoriginnode)(dns_db_t *db, dns_dbnode_t **nodep);
void (*transfernode)(dns_db_t *db, dns_dbnode_t **sourcep,
dns_dbnode_t **targetp);
isc_result_t (*getnsec3parameters)(dns_db_t *db,
dns_dbversion_t *version,
dns_hash_t *hash,
uint8_t *flags,
uint16_t *iterations,
unsigned char *salt,
size_t *salt_len);
isc_result_t (*findnsec3node)(dns_db_t *db, dns_name_t *name,
bool create,
dns_dbnode_t **nodep);
isc_result_t (*setsigningtime)(dns_db_t *db,
dns_rdataset_t *rdataset,
isc_stdtime_t resign);
isc_result_t (*getsigningtime)(dns_db_t *db,
dns_rdataset_t *rdataset,
dns_name_t *name);
void (*resigned)(dns_db_t *db, dns_rdataset_t *rdataset,
dns_dbversion_t *version);
bool (*isdnssec)(dns_db_t *db);
dns_stats_t *(*getrrsetstats)(dns_db_t *db);
void (*rpz_attach)(dns_db_t *db, dns_rpz_zones_t *rpzs,
dns_rpz_num_t rpz_num);
isc_result_t (*rpz_ready)(dns_db_t *db);
isc_result_t (*findnodeext)(dns_db_t *db, dns_name_t *name,
bool create,
dns_clientinfomethods_t *methods,
dns_clientinfo_t *clientinfo,
dns_dbnode_t **nodep);
isc_result_t (*findext)(dns_db_t *db, dns_name_t *name,
dns_dbversion_t *version,
dns_rdatatype_t type, unsigned int options,
isc_stdtime_t now,
dns_dbnode_t **nodep, dns_name_t *foundname,
dns_clientinfomethods_t *methods,
dns_clientinfo_t *clientinfo,
dns_rdataset_t *rdataset,
dns_rdataset_t *sigrdataset);
isc_result_t (*setcachestats)(dns_db_t *db, isc_stats_t *stats);
size_t (*hashsize)(dns_db_t *db);
isc_result_t (*nodefullname)(dns_db_t *db, dns_dbnode_t *node,
dns_name_t *name);
isc_result_t (*getsize)(dns_db_t *db, dns_dbversion_t *version,
uint64_t *records, uint64_t *bytes);
isc_result_t (*setservestalettl)(dns_db_t *db, dns_ttl_t ttl);
isc_result_t (*getservestalettl)(dns_db_t *db, dns_ttl_t *ttl);
} dns_dbmethods_t;
typedef isc_result_t
(*dns_dbcreatefunc_t)(isc_mem_t *mctx, dns_name_t *name,
dns_dbtype_t type, dns_rdataclass_t rdclass,
unsigned int argc, char *argv[], void *driverarg,
dns_db_t **dbp);
typedef isc_result_t
(*dns_dbupdate_callback_t)(dns_db_t *db, void *fn_arg);
#define DNS_DB_MAGIC ISC_MAGIC('D','N','S','D')
#define DNS_DB_VALID(db) ISC_MAGIC_VALID(db, DNS_DB_MAGIC)
/*%
* This structure is actually just the common prefix of a DNS db
* implementation's version of a dns_db_t.
* \brief
* Direct use of this structure by clients is forbidden. DB implementations
* may change the structure. 'magic' must be DNS_DB_MAGIC for any of the
* dns_db_ routines to work. DB implementations must maintain all DB
* invariants.
*/
struct dns_db {
unsigned int magic;
unsigned int impmagic;
dns_dbmethods_t * methods;
uint16_t attributes;
dns_rdataclass_t rdclass;
dns_name_t origin;
isc_ondestroy_t ondest;
isc_mem_t * mctx;
ISC_LIST(dns_dbonupdatelistener_t) update_listeners;
};
#define DNS_DBATTR_CACHE 0x01
#define DNS_DBATTR_STUB 0x02
struct dns_dbonupdatelistener {
dns_dbupdate_callback_t onupdate;
void * onupdate_arg;
ISC_LINK(dns_dbonupdatelistener_t) link;
};
/*@{*/
/*%
* Options that can be specified for dns_db_find().
*/
#define DNS_DBFIND_GLUEOK 0x0001
#define DNS_DBFIND_VALIDATEGLUE 0x0002
#define DNS_DBFIND_NOWILD 0x0004
#define DNS_DBFIND_PENDINGOK 0x0008
#define DNS_DBFIND_NOEXACT 0x0010
#define DNS_DBFIND_FORCENSEC 0x0020
#define DNS_DBFIND_COVERINGNSEC 0x0040
#define DNS_DBFIND_FORCENSEC3 0x0080
#define DNS_DBFIND_ADDITIONALOK 0x0100
#define DNS_DBFIND_NOZONECUT 0x0200
#define DNS_DBFIND_STALEOK 0x0400
/*@}*/
/*@{*/
/*%
* Options that can be specified for dns_db_addrdataset().
*/
#define DNS_DBADD_MERGE 0x01
#define DNS_DBADD_FORCE 0x02
#define DNS_DBADD_EXACT 0x04
#define DNS_DBADD_EXACTTTL 0x08
#define DNS_DBADD_PREFETCH 0x10
/*@}*/
/*%
* Options that can be specified for dns_db_subtractrdataset().
*/
#define DNS_DBSUB_EXACT 0x01
#define DNS_DBSUB_WANTOLD 0x02
/*@{*/
/*%
* Iterator options
*/
#define DNS_DB_RELATIVENAMES 0x1
#define DNS_DB_NSEC3ONLY 0x2
#define DNS_DB_NONSEC3 0x4
/*@}*/
/*****
***** Methods
*****/
/***
*** Basic DB Methods
***/
isc_result_t
dns_db_create(isc_mem_t *mctx, const char *db_type, dns_name_t *origin,
dns_dbtype_t type, dns_rdataclass_t rdclass,
unsigned int argc, char *argv[], dns_db_t **dbp);
/*%<
* Create a new database using implementation 'db_type'.
*
* Notes:
* \li All names in the database must be subdomains of 'origin' and in class
* 'rdclass'. The database makes its own copy of the origin, so the
* caller may do whatever they like with 'origin' and its storage once the
* call returns.
*
* \li DB implementation-specific parameters are passed using argc and argv.
*
* Requires:
*
* \li dbp != NULL and *dbp == NULL
*
* \li 'origin' is a valid absolute domain name.
*
* \li mctx is a valid memory context
*
* Ensures:
*
* \li A copy of 'origin' has been made for the databases use, and the
* caller is free to do whatever they want with the name and storage
* associated with 'origin'.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
* \li #ISC_R_NOTFOUND db_type not found
*
* \li Many other errors are possible, depending on what db_type was
* specified.
*/
void
dns_db_attach(dns_db_t *source, dns_db_t **targetp);
/*%<
* Attach *targetp to source.
*
* Requires:
*
* \li 'source' is a valid database.
*
* \li 'targetp' points to a NULL dns_db_t *.
*
* Ensures:
*
* \li *targetp is attached to source.
*/
void
dns_db_detach(dns_db_t **dbp);
/*%<
* Detach *dbp from its database.
*
* Requires:
*
* \li 'dbp' points to a valid database.
*
* Ensures:
*
* \li *dbp is NULL.
*
* \li If '*dbp' is the last reference to the database,
* all resources used by the database will be freed
*/
isc_result_t
dns_db_ondestroy(dns_db_t *db, isc_task_t *task, isc_event_t **eventp);
/*%<
* Causes 'eventp' to be sent to be sent to 'task' when the database is
* destroyed.
*
* Note; ownership of the eventp is taken from the caller (and *eventp is
* set to NULL). The sender field of the event is set to 'db' before it is
* sent to the task.
*/
bool
dns_db_iscache(dns_db_t *db);
/*%<
* Does 'db' have cache semantics?
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
* \li #true 'db' has cache semantics
* \li #false otherwise
*/
bool
dns_db_iszone(dns_db_t *db);
/*%<
* Does 'db' have zone semantics?
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
* \li #true 'db' has zone semantics
* \li #false otherwise
*/
bool
dns_db_isstub(dns_db_t *db);
/*%<
* Does 'db' have stub semantics?
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
* \li #true 'db' has zone semantics
* \li #false otherwise
*/
bool
dns_db_issecure(dns_db_t *db);
/*%<
* Is 'db' secure?
*
* Requires:
*
* \li 'db' is a valid database with zone semantics.
*
* Returns:
* \li #true 'db' is secure.
* \li #false 'db' is not secure.
*/
bool
dns_db_isdnssec(dns_db_t *db);
/*%<
* Is 'db' secure or partially secure?
*
* Requires:
*
* \li 'db' is a valid database with zone semantics.
*
* Returns:
* \li #true 'db' is secure or is partially.
* \li #false 'db' is not secure.
*/
dns_name_t *
dns_db_origin(dns_db_t *db);
/*%<
* The origin of the database.
*
* Note: caller must not try to change this name.
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
*
* \li The origin of the database.
*/
dns_rdataclass_t
dns_db_class(dns_db_t *db);
/*%<
* The class of the database.
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
*
* \li The class of the database.
*/
isc_result_t
dns_db_beginload(dns_db_t *db, dns_rdatacallbacks_t *callbacks);
/*%<
* Begin loading 'db'.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li This is the first attempt to load 'db'.
*
* \li 'callbacks' is a pointer to an initialized dns_rdatacallbacks_t
* structure.
*
* Ensures:
*
* \li On success, callbacks->add will be a valid dns_addrdatasetfunc_t
* suitable for loading records into 'db' from a raw or text zone
* file. callbacks->add_private will be a valid DB load context
* which should be used as 'arg' when callbacks->add is called.
* callbacks->deserialize will be a valid dns_deserialize_func_t
* suitable for loading 'db' from a map format zone file.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*
* \li Other results are possible, depending upon the database
* implementation used, syntax errors in the master file, etc.
*/
isc_result_t
dns_db_endload(dns_db_t *db, dns_rdatacallbacks_t *callbacks);
/*%<
* Finish loading 'db'.
*
* Requires:
*
* \li 'db' is a valid database that is being loaded.
*
* \li 'callbacks' is a valid dns_rdatacallbacks_t structure.
*
* \li callbacks->add_private is not NULL and is a valid database load context.
*
* Ensures:
*
* \li 'callbacks' is returned to its state prior to calling dns_db_beginload()
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*
* \li Other results are possible, depending upon the database
* implementation used, syntax errors in the master file, etc.
*/
isc_result_t
dns_db_load(dns_db_t *db, const char *filename);
isc_result_t
dns_db_load2(dns_db_t *db, const char *filename, dns_masterformat_t format);
isc_result_t
dns_db_load3(dns_db_t *db, const char *filename, dns_masterformat_t format,
unsigned int options);
/*%<
* Load master file 'filename' into 'db'.
*
* Notes:
* \li This routine is equivalent to calling
*
*\code
* dns_db_beginload();
* dns_master_loadfile();
* dns_db_endload();
*\endcode
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li This is the first attempt to load 'db'.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*
* \li Other results are possible, depending upon the database
* implementation used, syntax errors in the master file, etc.
*/
isc_result_t
dns_db_serialize(dns_db_t *db, dns_dbversion_t *version, FILE *rbtfile);
/*%<
* Dump version 'version' of 'db' to map-format file 'filename'.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'version' is a valid version.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*
* \li Other results are possible, depending upon the database
* implementation used, OS file errors, etc.
*/
isc_result_t
dns_db_dump(dns_db_t *db, dns_dbversion_t *version, const char *filename);
isc_result_t
dns_db_dump2(dns_db_t *db, dns_dbversion_t *version, const char *filename,
dns_masterformat_t masterformat);
/*%<
* Dump version 'version' of 'db' to master file 'filename'.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'version' is a valid version.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*
* \li Other results are possible, depending upon the database
* implementation used, OS file errors, etc.
*/
/***
*** Version Methods
***/
void
dns_db_currentversion(dns_db_t *db, dns_dbversion_t **versionp);
/*%<
* Open the current version for reading.
*
* Requires:
*
* \li 'db' is a valid database with zone semantics.
*
* \li versionp != NULL && *verisonp == NULL
*
* Ensures:
*
* \li On success, '*versionp' is attached to the current version.
*
*/
isc_result_t
dns_db_newversion(dns_db_t *db, dns_dbversion_t **versionp);
/*%<
* Open a new version for reading and writing.
*
* Requires:
*
* \li 'db' is a valid database with zone semantics.
*
* \li versionp != NULL && *verisonp == NULL
*
* Ensures:
*
* \li On success, '*versionp' is attached to the current version.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
void
dns_db_attachversion(dns_db_t *db, dns_dbversion_t *source,
dns_dbversion_t **targetp);
/*%<
* Attach '*targetp' to 'source'.
*
* Requires:
*
* \li 'db' is a valid database with zone semantics.
*
* \li source is a valid open version
*
* \li targetp != NULL && *targetp == NULL
*
* Ensures:
*
* \li '*targetp' is attached to source.
*/
void
dns_db_closeversion(dns_db_t *db, dns_dbversion_t **versionp,
bool commit);
/*%<
* Close version '*versionp'.
*
* Note: if '*versionp' is a read-write version and 'commit' is true,
* then all changes made in the version will take effect, otherwise they
* will be rolled back. The value of 'commit' is ignored for read-only
* versions.
*
* Requires:
*
* \li 'db' is a valid database with zone semantics.
*
* \li '*versionp' refers to a valid version.
*
* \li If committing a writable version, then there must be no other
* outstanding references to the version (e.g. an active rdataset
* iterator).
*
* Ensures:
*
* \li *versionp == NULL
*
* \li If *versionp is a read-write version, and commit is true, then
* the version will become the current version. If !commit, then all
* changes made in the version will be undone, and the version will
* not become the current version.
*/
/***
*** Node Methods
***/
isc_result_t
dns_db_findnode(dns_db_t *db, dns_name_t *name, bool create,
dns_dbnode_t **nodep);
isc_result_t
dns_db_findnodeext(dns_db_t *db, dns_name_t *name, bool create,
dns_clientinfomethods_t *methods,
dns_clientinfo_t *clientinfo, dns_dbnode_t **nodep);
/*%<
* Find the node with name 'name'.
*
* dns_db_findnodeext() (findnode extended) also accepts parameters
* 'methods' and 'clientinfo', which, when provided, enable the database to
* retrieve information about the client from the caller, and modify its
* response on the basis of that information.
*
* Notes:
* \li If 'create' is true and no node with name 'name' exists, then
* such a node will be created.
*
* \li This routine is for finding or creating a node with the specified
* name. There are no partial matches. It is not suitable for use
* in building responses to ordinary DNS queries; clients which wish
* to do that should use dns_db_find() instead.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'name' is a valid, non-empty, absolute name.
*
* \li nodep != NULL && *nodep == NULL
*
* Ensures:
*
* \li On success, *nodep is attached to the node with name 'name'.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTFOUND If !create and name not found.
* \li #ISC_R_NOMEMORY Can only happen if create is true.
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
isc_result_t
dns_db_find(dns_db_t *db, dns_name_t *name, dns_dbversion_t *version,
dns_rdatatype_t type, unsigned int options, isc_stdtime_t now,
dns_dbnode_t **nodep, dns_name_t *foundname,
dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset);
isc_result_t
dns_db_findext(dns_db_t *db, dns_name_t *name, dns_dbversion_t *version,
dns_rdatatype_t type, unsigned int options, isc_stdtime_t now,
dns_dbnode_t **nodep, dns_name_t *foundname,
dns_clientinfomethods_t *methods, dns_clientinfo_t *clientinfo,
dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset);
/*%<
* Find the best match for 'name' and 'type' in version 'version' of 'db'.
*
* dns_db_findext() (find extended) also accepts parameters 'methods'
* and 'clientinfo', which when provided enable the database to retrieve
* information about the client from the caller, and modify its response
* on the basis of this information.
*
* Notes:
*
* \li If type == dns_rdataset_any, then rdataset will not be bound.
*
* \li If 'options' does not have #DNS_DBFIND_GLUEOK set, then no glue will
* be returned. For zone databases, glue is as defined in RFC2181.
* For cache databases, glue is any rdataset with a trust of
* dns_trust_glue.
*
* \li If 'options' does not have #DNS_DBFIND_ADDITIONALOK set, then no
* additional records will be returned. Only caches can have
* rdataset with trust dns_trust_additional.
*
* \li If 'options' does not have #DNS_DBFIND_PENDINGOK set, then no
* pending data will be returned. This option is only meaningful for
* cache databases.
*
* \li If the #DNS_DBFIND_NOWILD option is set, then wildcard matching will
* be disabled. This option is only meaningful for zone databases.
*
* \li If the #DNS_DBFIND_NOZONECUT option is set, the database is
* assumed to contain no zone cuts above 'name'. An implementation
* may therefore choose to search for a match beginning at 'name'
* rather than walking down the tree to check check for delegations.
* If #DNS_DBFIND_NOWILD is not set, wildcard matching will be
* attempted at each node starting at the direct ancestor of 'name'
* and working up to the zone origin. This option is only meaningful
* when querying redirect zones.
*
* \li If the #DNS_DBFIND_FORCENSEC option is set, the database is assumed to
* have NSEC records, and these will be returned when appropriate. This
* is only necessary when querying a database that was not secure
* when created.
*
* \li If the DNS_DBFIND_COVERINGNSEC option is set, then look for a
* NSEC record that potentially covers 'name' if a answer cannot
* be found. Note the returned NSEC needs to be checked to ensure
* that it is correct. This only affects answers returned from the
* cache.
*
* \li If the #DNS_DBFIND_FORCENSEC3 option is set, then we are looking
* in the NSEC3 tree and not the main tree. Without this option being
* set NSEC3 records will not be found.
*
* \li To respond to a query for SIG records, the caller should create a
* rdataset iterator and extract the signatures from each rdataset.
*
* \li Making queries of type ANY with #DNS_DBFIND_GLUEOK is not recommended,
* because the burden of determining whether a given rdataset is valid
* glue or not falls upon the caller.
*
* \li The 'now' field is ignored if 'db' is a zone database. If 'db' is a
* cache database, an rdataset will not be found unless it expires after
* 'now'. Any ANY query will not match unless at least one rdataset at
* the node expires after 'now'. If 'now' is zero, then the current time
* will be used.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'type' is not SIG, or a meta-RR type other than 'ANY' (e.g. 'OPT').
*
* \li 'nodep' is NULL, or nodep is a valid pointer and *nodep == NULL.
*
* \li 'foundname' is a valid name with a dedicated buffer.
*
* \li 'rdataset' is NULL, or is a valid unassociated rdataset.
*
* Ensures,
* on a non-error completion:
*
* \li If nodep != NULL, then it is bound to the found node.
*
* \li If foundname != NULL, then it contains the full name of the
* found node.
*
* \li If rdataset != NULL and type != dns_rdatatype_any, then
* rdataset is bound to the found rdataset.
*
* Non-error results are:
*
* \li #ISC_R_SUCCESS The desired node and type were
* found.
*
* \li #DNS_R_GLUE The desired node and type were
* found, but are glue. This
* result can only occur if
* the DNS_DBFIND_GLUEOK option
* is set. This result can only
* occur if 'db' is a zone
* database. If type ==
* dns_rdatatype_any, then the
* node returned may contain, or
* consist entirely of invalid
* glue (i.e. data occluded by a
* zone cut). The caller must
* take care not to return invalid
* glue to a client.
*
* \li #DNS_R_DELEGATION The data requested is beneath
* a zone cut. node, foundname,
* and rdataset reference the
* NS RRset of the zone cut.
* If 'db' is a cache database,
* then this is the deepest known
* delegation.
*
* \li #DNS_R_ZONECUT type == dns_rdatatype_any, and
* the desired node is a zonecut.
* The caller must take care not
* to return inappropriate glue
* to a client. This result can
* only occur if 'db' is a zone
* database and DNS_DBFIND_GLUEOK
* is set.
*
* \li #DNS_R_DNAME The data requested is beneath
* a DNAME. node, foundname,
* and rdataset reference the
* DNAME RRset.
*
* \li #DNS_R_CNAME The rdataset requested was not
* found, but there is a CNAME
* at the desired name. node,
* foundname, and rdataset
* reference the CNAME RRset.
*
* \li #DNS_R_NXDOMAIN The desired name does not
* exist.
*
* \li #DNS_R_NXRRSET The desired name exists, but
* the desired type does not.
*
* \li #ISC_R_NOTFOUND The desired name does not
* exist, and no delegation could
* be found. This result can only
* occur if 'db' is a cache
* database. The caller should
* use its nameserver(s) of last
* resort (e.g. root hints).
*
* \li #DNS_R_NCACHENXDOMAIN The desired name does not
* exist. 'node' is bound to the
* cache node with the desired
* name, and 'rdataset' contains
* the negative caching proof.
*
* \li #DNS_R_NCACHENXRRSET The desired type does not
* exist. 'node' is bound to the
* cache node with the desired
* name, and 'rdataset' contains
* the negative caching proof.
*
* \li #DNS_R_EMPTYNAME The name exists but there is
* no data at the name.
*
* \li #DNS_R_COVERINGNSEC The returned data is a NSEC
* that potentially covers 'name'.
*
* \li #DNS_R_EMPTYWILD The name is a wildcard without
* resource records.
*
* Error results:
*
* \li #ISC_R_NOMEMORY
*
* \li #DNS_R_BADDB Data that is required to be
* present in the DB, e.g. an NSEC
* record in a secure zone, is not
* present.
*
* \li Other results are possible, and should all be treated as
* errors.
*/
isc_result_t
dns_db_findzonecut(dns_db_t *db, dns_name_t *name,
unsigned int options, isc_stdtime_t now,
dns_dbnode_t **nodep, dns_name_t *foundname,
dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset);
/*%<
* Find the deepest known zonecut which encloses 'name' in 'db'.
*
* Notes:
*
* \li If the #DNS_DBFIND_NOEXACT option is set, then the zonecut returned
* (if any) will be the deepest known ancestor of 'name'.
*
* \li If 'now' is zero, then the current time will be used.
*
* Requires:
*
* \li 'db' is a valid database with cache semantics.
*
* \li 'nodep' is NULL, or nodep is a valid pointer and *nodep == NULL.
*
* \li 'foundname' is a valid name with a dedicated buffer.
*
* \li 'rdataset' is NULL, or is a valid unassociated rdataset.
*
* Ensures, on a non-error completion:
*
* \li If nodep != NULL, then it is bound to the found node.
*
* \li If foundname != NULL, then it contains the full name of the
* found node.
*
* \li If rdataset != NULL and type != dns_rdatatype_any, then
* rdataset is bound to the found rdataset.
*
* Non-error results are:
*
* \li #ISC_R_SUCCESS
*
* \li #ISC_R_NOTFOUND
*
* \li Other results are possible, and should all be treated as
* errors.
*/
void
dns_db_attachnode(dns_db_t *db, dns_dbnode_t *source, dns_dbnode_t **targetp);
/*%<
* Attach *targetp to source.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'source' is a valid node.
*
* \li 'targetp' points to a NULL dns_dbnode_t *.
*
* Ensures:
*
* \li *targetp is attached to source.
*/
void
dns_db_detachnode(dns_db_t *db, dns_dbnode_t **nodep);
/*%<
* Detach *nodep from its node.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'nodep' points to a valid node.
*
* Ensures:
*
* \li *nodep is NULL.
*/
void
dns_db_transfernode(dns_db_t *db, dns_dbnode_t **sourcep,
dns_dbnode_t **targetp);
/*%<
* Transfer a node between pointer.
*
* This is equivalent to calling dns_db_attachnode() then dns_db_detachnode().
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li '*sourcep' is a valid node.
*
* \li 'targetp' points to a NULL dns_dbnode_t *.
*
* Ensures:
*
* \li '*sourcep' is NULL.
*/
isc_result_t
dns_db_expirenode(dns_db_t *db, dns_dbnode_t *node, isc_stdtime_t now);
/*%<
* Mark as stale all records at 'node' which expire at or before 'now'.
*
* Note: if 'now' is zero, then the current time will be used.
*
* Requires:
*
* \li 'db' is a valid cache database.
*
* \li 'node' is a valid node.
*/
void
dns_db_printnode(dns_db_t *db, dns_dbnode_t *node, FILE *out);
/*%<
* Print a textual representation of the contents of the node to
* 'out'.
*
* Note: this function is intended for debugging, not general use.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'node' is a valid node.
*/
/***
*** DB Iterator Creation
***/
isc_result_t
dns_db_createiterator(dns_db_t *db, unsigned int options,
dns_dbiterator_t **iteratorp);
/*%<
* Create an iterator for version 'version' of 'db'.
*
* Notes:
*
* \li One or more of the following options can be set.
* #DNS_DB_RELATIVENAMES
* #DNS_DB_NSEC3ONLY
* #DNS_DB_NONSEC3
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li iteratorp != NULL && *iteratorp == NULL
*
* Ensures:
*
* \li On success, *iteratorp will be a valid database iterator.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*/
/***
*** Rdataset Methods
***/
/*
* XXXRTH Should we check for glue and pending data in dns_db_findrdataset()?
*/
isc_result_t
dns_db_findrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
dns_rdatatype_t type, dns_rdatatype_t covers,
isc_stdtime_t now, dns_rdataset_t *rdataset,
dns_rdataset_t *sigrdataset);
/*%<
* Search for an rdataset of type 'type' at 'node' that are in version
* 'version' of 'db'. If found, make 'rdataset' refer to it.
*
* Notes:
*
* \li If 'version' is NULL, then the current version will be used.
*
* \li Care must be used when using this routine to build a DNS response:
* 'node' should have been found with dns_db_find(), not
* dns_db_findnode(). No glue checking is done. No checking for
* pending data is done.
*
* \li The 'now' field is ignored if 'db' is a zone database. If 'db' is a
* cache database, an rdataset will not be found unless it expires after
* 'now'. If 'now' is zero, then the current time will be used.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'node' is a valid node.
*
* \li 'rdataset' is a valid, disassociated rdataset.
*
* \li 'sigrdataset' is a valid, disassociated rdataset, or it is NULL.
*
* \li If 'covers' != 0, 'type' must be SIG.
*
* \li 'type' is not a meta-RR type such as 'ANY' or 'OPT'.
*
* Ensures:
*
* \li On success, 'rdataset' is associated with the found rdataset.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTFOUND
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
isc_result_t
dns_db_allrdatasets(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
isc_stdtime_t now, dns_rdatasetiter_t **iteratorp);
/*%<
* Make '*iteratorp' an rdataset iterator for all rdatasets at 'node' in
* version 'version' of 'db'.
*
* Notes:
*
* \li If 'version' is NULL, then the current version will be used.
*
* \li The 'now' field is ignored if 'db' is a zone database. If 'db' is a
* cache database, an rdataset will not be found unless it expires after
* 'now'. Any ANY query will not match unless at least one rdataset at
* the node expires after 'now'. If 'now' is zero, then the current time
* will be used.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'node' is a valid node.
*
* \li iteratorp != NULL && *iteratorp == NULL
*
* Ensures:
*
* \li On success, '*iteratorp' is a valid rdataset iterator.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTFOUND
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
isc_result_t
dns_db_addrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
isc_stdtime_t now, dns_rdataset_t *rdataset,
unsigned int options, dns_rdataset_t *addedrdataset);
/*%<
* Add 'rdataset' to 'node' in version 'version' of 'db'.
*
* Notes:
*
* \li If the database has zone semantics, the #DNS_DBADD_MERGE option is set,
* and an rdataset of the same type as 'rdataset' already exists at
* 'node' then the contents of 'rdataset' will be merged with the existing
* rdataset. If the option is not set, then rdataset will replace any
* existing rdataset of the same type. If not merging and the
* #DNS_DBADD_FORCE option is set, then the data will update the database
* without regard to trust levels. If not forcing the data, then the
* rdataset will only be added if its trust level is >= the trust level of
* any existing rdataset. Forcing is only meaningful for cache databases.
* If #DNS_DBADD_EXACT is set then there must be no rdata in common between
* the old and new rdata sets. If #DNS_DBADD_EXACTTTL is set then both
* the old and new rdata sets must have the same ttl.
*
* \li The 'now' field is ignored if 'db' is a zone database. If 'db' is
* a cache database, then the added rdataset will expire no later than
* now + rdataset->ttl.
*
* \li If 'addedrdataset' is not NULL, then it will be attached to the
* resulting new rdataset in the database, or to the existing data if
* the existing data was better.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'node' is a valid node.
*
* \li 'rdataset' is a valid, associated rdataset with the same class
* as 'db'.
*
* \li 'addedrdataset' is NULL, or a valid, unassociated rdataset.
*
* \li The database has zone semantics and 'version' is a valid
* read-write version, or the database has cache semantics
* and version is NULL.
*
* \li If the database has cache semantics, the #DNS_DBADD_MERGE option must
* not be set.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #DNS_R_UNCHANGED The operation did not change anything.
* \li #ISC_R_NOMEMORY
* \li #DNS_R_NOTEXACT
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
isc_result_t
dns_db_subtractrdataset(dns_db_t *db, dns_dbnode_t *node,
dns_dbversion_t *version, dns_rdataset_t *rdataset,
unsigned int options, dns_rdataset_t *newrdataset);
/*%<
* Remove any rdata in 'rdataset' from 'node' in version 'version' of
* 'db'.
*
* Notes:
*
* \li If 'newrdataset' is not NULL, then it will be attached to the
* resulting new rdataset in the database, unless the rdataset has
* become nonexistent. If DNS_DBSUB_EXACT is set then all elements
* of 'rdataset' must exist at 'node'.
*
*\li If DNS_DBSUB_WANTOLD is set and the entire rdataset was deleted
* then return the original rdatatset in newrdataset if that existed.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'node' is a valid node.
*
* \li 'rdataset' is a valid, associated rdataset with the same class
* as 'db'.
*
* \li 'newrdataset' is NULL, or a valid, unassociated rdataset.
*
* \li The database has zone semantics and 'version' is a valid
* read-write version.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #DNS_R_UNCHANGED The operation did not change anything.
* \li #DNS_R_NXRRSET All rdata of the same type as those
* in 'rdataset' have been deleted.
* \li #DNS_R_NOTEXACT Some part of 'rdataset' did not
* exist and DNS_DBSUB_EXACT was set.
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
isc_result_t
dns_db_deleterdataset(dns_db_t *db, dns_dbnode_t *node,
dns_dbversion_t *version, dns_rdatatype_t type,
dns_rdatatype_t covers);
/*%<
* Make it so that no rdataset of type 'type' exists at 'node' in version
* version 'version' of 'db'.
*
* Notes:
*
* \li If 'type' is dns_rdatatype_any, then no rdatasets will exist in
* 'version' (provided that the dns_db_deleterdataset() isn't followed
* by one or more dns_db_addrdataset() calls).
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'node' is a valid node.
*
* \li The database has zone semantics and 'version' is a valid
* read-write version, or the database has cache semantics
* and version is NULL.
*
* \li 'type' is not a meta-RR type, except for dns_rdatatype_any, which is
* allowed.
*
* \li If 'covers' != 0, 'type' must be SIG.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #DNS_R_UNCHANGED No rdatasets of 'type' existed before
* the operation was attempted.
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
isc_result_t
dns_db_getsoaserial(dns_db_t *db, dns_dbversion_t *ver, uint32_t *serialp);
/*%<
* Get the current SOA serial number from a zone database.
*
* Requires:
* \li 'db' is a valid database with zone semantics.
* \li 'ver' is a valid version.
*/
void
dns_db_overmem(dns_db_t *db, bool overmem);
/*%<
* Enable / disable aggressive cache cleaning.
*/
unsigned int
dns_db_nodecount(dns_db_t *db);
/*%<
* Count the number of nodes in 'db'.
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
* \li The number of nodes in the database
*/
size_t
dns_db_hashsize(dns_db_t *db);
/*%<
* For database implementations using a hash table, report the
* current number of buckets.
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
* \li The number of buckets in the database's hash table, or
* 0 if not implemented.
*/
void
dns_db_settask(dns_db_t *db, isc_task_t *task);
/*%<
* If task is set then the final detach maybe performed asynchronously.
*
* Requires:
* \li 'db' is a valid database.
* \li 'task' to be valid or NULL.
*/
bool
dns_db_ispersistent(dns_db_t *db);
/*%<
* Is 'db' persistent? A persistent database does not need to be loaded
* from disk or written to disk.
*
* Requires:
*
* \li 'db' is a valid database.
*
* Returns:
* \li #true 'db' is persistent.
* \li #false 'db' is not persistent.
*/
isc_result_t
dns_db_register(const char *name, dns_dbcreatefunc_t create, void *driverarg,
isc_mem_t *mctx, dns_dbimplementation_t **dbimp);
/*%<
* Register a new database implementation and add it to the list of
* supported implementations.
*
* Requires:
*
* \li 'name' is not NULL
* \li 'order' is a valid function pointer
* \li 'mctx' is a valid memory context
* \li dbimp != NULL && *dbimp == NULL
*
* Returns:
* \li #ISC_R_SUCCESS The registration succeeded
* \li #ISC_R_NOMEMORY Out of memory
* \li #ISC_R_EXISTS A database implementation with the same name exists
*
* Ensures:
*
* \li *dbimp points to an opaque structure which must be passed to
* dns_db_unregister().
*/
void
dns_db_unregister(dns_dbimplementation_t **dbimp);
/*%<
* Remove a database implementation from the list of supported
* implementations. No databases of this type can be active when this
* is called.
*
* Requires:
* \li dbimp != NULL && *dbimp == NULL
*
* Ensures:
*
* \li Any memory allocated in *dbimp will be freed.
*/
isc_result_t
dns_db_getoriginnode(dns_db_t *db, dns_dbnode_t **nodep);
/*%<
* Get the origin DB node corresponding to the DB's zone. This function
* should typically succeed unless the underlying DB implementation doesn't
* support the feature.
*
* Requires:
*
* \li 'db' is a valid zone database.
* \li 'nodep' != NULL && '*nodep' == NULL
*
* Ensures:
* \li On success, '*nodep' will point to the DB node of the zone's origin.
*
* Returns:
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTFOUND - the DB implementation does not support this feature.
*/
isc_result_t
dns_db_getnsec3parameters(dns_db_t *db, dns_dbversion_t *version,
dns_hash_t *hash, uint8_t *flags,
uint16_t *iterations,
unsigned char *salt, size_t *salt_length);
/*%<
* Get the NSEC3 parameters that are associated with this zone.
*
* Requires:
* \li 'db' is a valid zone database.
*
* Returns:
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTFOUND - the DB implementation does not support this feature
* or this zone does not have NSEC3 records.
*/
isc_result_t
dns_db_getsize(dns_db_t *db, dns_dbversion_t *version, uint64_t *records,
uint64_t *bytes);
/*%<
* Get the number of records in the given version of the database as well
* as the number bytes used to store those records.
*
* Requires:
* \li 'db' is a valid zone database.
* \li 'version' is NULL or a valid version.
* \li 'records' is NULL or a pointer to return the record count in.
* \li 'bytes' is NULL or a pointer to return the byte count in.
*
* Returns:
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTIMPLEMENTED
*/
isc_result_t
dns_db_findnsec3node(dns_db_t *db, dns_name_t *name,
bool create, dns_dbnode_t **nodep);
/*%<
* Find the NSEC3 node with name 'name'.
*
* Notes:
* \li If 'create' is true and no node with name 'name' exists, then
* such a node will be created.
*
* Requires:
*
* \li 'db' is a valid database.
*
* \li 'name' is a valid, non-empty, absolute name.
*
* \li nodep != NULL && *nodep == NULL
*
* Ensures:
*
* \li On success, *nodep is attached to the node with name 'name'.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTFOUND If !create and name not found.
* \li #ISC_R_NOMEMORY Can only happen if create is true.
*
* \li Other results are possible, depending upon the database
* implementation used.
*/
isc_result_t
dns_db_setsigningtime(dns_db_t *db, dns_rdataset_t *rdataset,
isc_stdtime_t resign);
/*%<
* Sets the re-signing time associated with 'rdataset' to 'resign'.
*
* Requires:
* \li 'db' is a valid zone database.
* \li 'rdataset' is or is to be associated with 'db'.
* \li 'rdataset' is not pending removed from the heap via an
* uncommitted call to dns_db_resigned().
*
* Returns:
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
* \li #ISC_R_NOTIMPLEMENTED - Not supported by this DB implementation.
*/
isc_result_t
dns_db_getsigningtime(dns_db_t *db, dns_rdataset_t *rdataset, dns_name_t *name);
/*%<
* Return the rdataset with the earliest signing time in the zone.
* Note: the rdataset is version agnostic.
*
* Requires:
* \li 'db' is a valid zone database.
* \li 'rdataset' to be initialized but not associated.
* \li 'name' to be NULL or have a buffer associated with it.
*
* Returns:
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTFOUND - No dataset exists.
*/
void
dns_db_resigned(dns_db_t *db, dns_rdataset_t *rdataset,
dns_dbversion_t *version);
/*%<
* Mark 'rdataset' as not being available to be returned by
* dns_db_getsigningtime(). If the changes associated with 'version'
* are committed this will be permanent. If the version is not committed
* this change will be rolled back when the version is closed. Until
* 'version' is either committed or rolled back, 'rdataset' can no longer
* be acted upon by dns_db_setsigningtime().
*
* Requires:
* \li 'db' is a valid zone database.
* \li 'rdataset' to be associated with 'db'.
* \li 'version' to be open for writing.
*/
dns_stats_t *
dns_db_getrrsetstats(dns_db_t *db);
/*%<
* Get statistics information counting RRsets stored in the DB, when available.
* The statistics may not be available depending on the DB implementation.
*
* Requires:
*
* \li 'db' is a valid database (cache only).
*
* Returns:
* \li when available, a pointer to a statistics object created by
* dns_rdatasetstats_create(); otherwise NULL.
*/
isc_result_t
dns_db_setcachestats(dns_db_t *db, isc_stats_t *stats);
/*%<
* Set the location in which to collect cache statistics.
* This option may not exist depending on the DB implementation.
*
* Requires:
*
* \li 'db' is a valid database (cache only).
*
* Returns:
* \li when available, a pointer to a statistics object created by
* dns_rdatasetstats_create(); otherwise NULL.
*/
void
dns_db_rpz_attach(dns_db_t *db, dns_rpz_zones_t *rpzs, dns_rpz_num_t rpz_num);
/*%<
* Attach the response policy information for a view to a database for a
* zone for the view.
*/
isc_result_t
dns_db_rpz_ready(dns_db_t *db);
/*%<
* Finish loading a response policy zone.
*/
isc_result_t
dns_db_updatenotify_register(dns_db_t *db,
dns_dbupdate_callback_t fn,
void *fn_arg);
/*%<
* Register a notify-on-update callback function to a database.
*
* Requires:
*
* \li 'db' is a valid database
* \li 'db' does not have an update callback registered
* \li 'fn' is not NULL
*
*/
isc_result_t
dns_db_updatenotify_unregister(dns_db_t *db,
dns_dbupdate_callback_t fn,
void *fn_arg);
/*%<
* Unregister a notify-on-update callback.
*
* Requires:
*
* \li 'db' is a valid database
* \li 'db' has update callback registered
*
*/
isc_result_t
dns_db_nodefullname(dns_db_t *db, dns_dbnode_t *node, dns_name_t *name);
/*%<
* Get the name associated with a database node.
*
* Requires:
*
* \li 'db' is a valid database
* \li 'node' and 'name' are not NULL
*/
isc_result_t
dns_db_setservestalettl(dns_db_t *db, dns_ttl_t ttl);
/*%<
* Sets the maximum length of time that cached answers may be retained
* past their normal TTL. Default value for the library is 0, disabling
* the use of stale data.
*
* Requires:
* \li 'db' is a valid cache database.
* \li 'ttl' is the number of seconds to retain data past its normal expiry.
*
* Returns:
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTIMPLEMENTED - Not supported by this DB implementation.
*/
isc_result_t
dns_db_getservestalettl(dns_db_t *db, dns_ttl_t *ttl);
/*%<
* Gets maximum length of time that cached answers may be kept past
* normal TTL expiration.
*
* Requires:
* \li 'db' is a valid cache database.
* \li 'ttl' is the number of seconds to retain data past its normal expiry.
*
* Returns:
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOTIMPLEMENTED - Not supported by this DB implementation.
*/
ISC_LANG_ENDDECLS
#endif /* DNS_DB_H */
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