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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0
*
* 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.
*/
#pragma once
/*****
***** Module Info
*****/
/*! \file
*
* \brief
* The DNS client module provides convenient programming interfaces to various
* DNS services, such as name resolution with or without DNSSEC validation or
* dynamic DNS update. This module is primarily expected to be used by other
* applications than BIND9-related ones that need such advanced DNS features.
*
* MP:
*\li In the typical usage of this module, application threads will not share
* the same data structures created and manipulated in this module.
* However, the module still ensures appropriate synchronization of such
* data structures.
*
* Resources:
*\li TBS
*
* Security:
*\li This module does not handle any low-level data directly, and so no
* security issue specific to this module is anticipated.
*/
#include <isc/event.h>
#include <isc/sockaddr.h>
#include <dns/tsig.h>
#include <dns/types.h>
#include <dst/dst.h>
ISC_LANG_BEGINDECLS
/***
*** Types
***/
/*%
* Optional flags for dns_client_(start)resolve.
*/
/*%< Do not return DNSSEC data (e.g. RRSIGS) with response. */
#define DNS_CLIENTRESOPT_NODNSSEC 0x01
/*%< Allow running external context. */
#define DNS_CLIENTRESOPT_RESERVED 0x02
/*%< Don't validate responses. */
#define DNS_CLIENTRESOPT_NOVALIDATE 0x04
/*%< Don't set the CD flag on upstream queries. */
#define DNS_CLIENTRESOPT_NOCDFLAG 0x08
/*%< Use TCP transport. */
#define DNS_CLIENTRESOPT_TCP 0x10
/*%
* View name used in dns_client.
*/
#define DNS_CLIENTVIEW_NAME "_dnsclient"
/*%
* A dns_clientresevent_t is sent when name resolution performed by a client
* completes. 'result' stores the result code of the entire resolution
* procedure. 'vresult' specifically stores the result code of DNSSEC
* validation if it is performed. When name resolution successfully completes,
* 'answerlist' is typically non empty, containing answer names along with
* RRsets. It is the receiver's responsibility to free this list by calling
* dns_client_freeresanswer() before freeing the event structure.
*/
typedef struct dns_clientresevent {
ISC_EVENT_COMMON(struct dns_clientresevent);
isc_result_t result;
isc_result_t vresult;
dns_namelist_t answerlist;
} dns_clientresevent_t; /* too long? */
isc_result_t
dns_client_create(isc_mem_t *mctx, isc_appctx_t *actx, isc_taskmgr_t *taskmgr,
isc_nm_t *nm, isc_timermgr_t *timermgr, unsigned int options,
dns_client_t **clientp, const isc_sockaddr_t *localaddr4,
const isc_sockaddr_t *localaddr6);
/*%<
* Create a DNS client object with minimal internal resources, such as
* a default view for the IN class and IPv4/IPv6 dispatches for the view.
*
* dns_client_create() takes 'manager' arguments so that the caller can
* control the behavior of the client through the underlying event framework.
* 'localaddr4' and 'localaddr6' specify the local addresses to use for
* each address family; if both are set to NULL, then wildcard addresses
* will be used for both families. If only one is NULL, then the other
* address will be used as the local address, and the NULL protocol family
* will not be used.
*
* Requires:
*
*\li 'mctx' is a valid memory context.
*
*\li 'actx' is a valid application context.
*
*\li 'taskmgr' is a valid task manager.
*
*\li 'nm' is a valid network manager.
*
*\li 'timermgr' is a valid timer manager.
*
*\li clientp != NULL && *clientp == NULL.
*
* Returns:
*
*\li #ISC_R_SUCCESS On success.
*
*\li Anything else Failure.
*/
void
dns_client_detach(dns_client_t **clientp);
/*%<
* Detach 'client' and destroy it if there are no more references.
*
* Requires:
*
*\li '*clientp' is a valid client.
*
* Ensures:
*
*\li *clientp == NULL.
*/
isc_result_t
dns_client_setservers(dns_client_t *client, dns_rdataclass_t rdclass,
const dns_name_t *name_space, isc_sockaddrlist_t *addrs);
/*%<
* Specify a list of addresses of recursive name servers that the client will
* use for name resolution. A view for the 'rdclass' class must be created
* beforehand. If 'name_space' is non NULL, the specified server will be used
* if and only if the query name is a subdomain of 'name_space'. When servers
* for multiple 'name_space's are provided, and a query name is covered by
* more than one 'name_space', the servers for the best (longest) matching
* name_space will be used. If 'name_space' is NULL, it works as if
* dns_rootname (.) were specified.
*
* Requires:
*
*\li 'client' is a valid client.
*
*\li 'name_space' is NULL or a valid name.
*
*\li 'addrs' != NULL.
*
* Returns:
*
*\li #ISC_R_SUCCESS On success.
*
*\li Anything else Failure.
*/
isc_result_t
dns_client_clearservers(dns_client_t *client, dns_rdataclass_t rdclass,
const dns_name_t *name_space);
/*%<
* Remove configured recursive name servers for the 'rdclass' and 'name_space'
* from the client. See the description of dns_client_setservers() for
* the requirements about 'rdclass' and 'name_space'.
*
* Requires:
*
*\li 'client' is a valid client.
*
*\li 'name_space' is NULL or a valid name.
*
* Returns:
*
*\li #ISC_R_SUCCESS On success.
*
*\li Anything else Failure.
*/
isc_result_t
dns_client_resolve(dns_client_t *client, const dns_name_t *name,
dns_rdataclass_t rdclass, dns_rdatatype_t type,
unsigned int options, dns_namelist_t *namelist);
isc_result_t
dns_client_startresolve(dns_client_t *client, const dns_name_t *name,
dns_rdataclass_t rdclass, dns_rdatatype_t type,
unsigned int options, isc_task_t *task,
isc_taskaction_t action, void *arg,
dns_clientrestrans_t **transp);
/*%<
* Perform name resolution for 'name', 'rdclass', and 'type'.
*
* If any trusted keys are configured and the query name is considered to
* belong to a secure zone, these functions also validate the responses
* using DNSSEC by default. If the DNS_CLIENTRESOPT_NOVALIDATE flag is set
* in 'options', DNSSEC validation is disabled regardless of the configured
* trusted keys or the query name. With DNS_CLIENTRESOPT_NODNSSEC
* DNSSEC data is not returned with response. DNS_CLIENTRESOPT_NOCDFLAG
* disables the CD flag on queries, DNS_CLIENTRESOPT_TCP switches to
* the TCP (vs. UDP) transport.
*
* dns_client_resolve() provides a synchronous service. This function starts
* name resolution internally and blocks until it completes. On success,
* 'namelist' will contain a list of answer names, each of which has
* corresponding RRsets. The caller must provide a valid empty list, and
* is responsible for freeing the list content via dns_client_freeresanswer().
* If the name resolution fails due to an error in DNSSEC validation,
* dns_client_resolve() returns the result code indicating the validation
* error. Otherwise, it returns the result code of the entire resolution
* process, either success or failure.
*
* It is expected that the client object passed to dns_client_resolve() was
* created via dns_client_create() and has external managers and contexts.
*
* dns_client_startresolve() is an asynchronous version of dns_client_resolve()
* and does not block. When name resolution is completed, 'action' will be
* called with the argument of a 'dns_clientresevent_t' object, which contains
* the resulting list of answer names (on success). On return, '*transp' is
* set to an opaque transaction ID so that the caller can cancel this
* resolution process.
*
* Requires:
*
*\li 'client' is a valid client.
*
*\li 'addrs' != NULL.
*
*\li 'name' is a valid name.
*
*\li 'namelist' != NULL and is not empty.
*
*\li 'task' is a valid task.
*
*\li 'transp' != NULL && *transp == NULL;
*
* Returns:
*
*\li #ISC_R_SUCCESS On success.
*
*\li Anything else Failure.
*/
void
dns_client_freeresanswer(dns_client_t *client, dns_namelist_t *namelist);
/*%<
* Free resources allocated for the content of 'namelist'.
*
* Requires:
*
*\li 'client' is a valid client.
*
*\li 'namelist' != NULL.
*/
isc_result_t
dns_client_addtrustedkey(dns_client_t *client, dns_rdataclass_t rdclass,
dns_rdatatype_t rdtype, const dns_name_t *keyname,
isc_buffer_t *keydatabuf);
/*%<
* Add a DNSSEC trusted key for the 'rdclass' class. A view for the 'rdclass'
* class must be created beforehand. 'rdtype' is the type of the RR data
* for the key, either DNSKEY or DS. 'keyname' is the DNS name of the key,
* and 'keydatabuf' stores the RR data.
*
* Requires:
*
*\li 'client' is a valid client.
*
*\li 'keyname' is a valid name.
*
*\li 'keydatabuf' is a valid buffer.
*
* Returns:
*
*\li #ISC_R_SUCCESS On success.
*
*\li Anything else Failure.
*/
ISC_LANG_ENDDECLS
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