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dns
client.h
/* * 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_CLIENT_H #define DNS_CLIENT_H 1 /***** ***** 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> typedef enum { updateop_none = 0, updateop_add = 1, updateop_delete = 2, updateop_exist = 3, updateop_notexist = 4, updateop_max = 5 } dns_client_updateop_t; ISC_LANG_BEGINDECLS /*** *** Types ***/ /*% * Optional flags for dns_client_create(x). */ /*%< Enable caching resolution results (experimental). */ #define DNS_CLIENTCREATEOPT_USECACHE 0x8000 /*% * 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_ALLOWRUN 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 /*% * Optional flags for dns_client_(start)request. */ /*%< Allow running external context. */ #define DNS_CLIENTREQOPT_ALLOWRUN 0x01 /*%< Use TCP transport. */ #define DNS_CLIENTREQOPT_TCP 0x02 /*% * Optional flags for dns_client_(start)update. */ /*%< Allow running external context. */ #define DNS_CLIENTUPDOPT_ALLOWRUN 0x01 /*%< Use TCP transport. */ #define DNS_CLIENTUPDOPT_TCP 0x02 /*% * 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? */ /*% * Status of a dynamic update procedure. */ typedef enum { dns_clientupdatestate_prepare, /*%< no updates have been sent */ dns_clientupdatestate_sent, /*%< updates were sent, no response */ dns_clientupdatestate_done /*%< update was sent and succeeded */ } dns_clientupdatestate_t; /*% * A dns_clientreqevent_t is sent when a DNS request is completed by a client. * 'result' stores the result code of the entire transaction. * If the transaction is successfully completed but the response packet cannot * be parsed, 'result' will store the result code of dns_message_parse(). * If the response packet is received, 'rmessage' will contain the response * message, whether it is successfully parsed or not. */ typedef struct dns_clientreqevent { ISC_EVENT_COMMON(struct dns_clientreqevent); isc_result_t result; dns_message_t *rmessage; } dns_clientreqevent_t; /* too long? */ /*% * A dns_clientupdateevent_t is sent when dynamic update performed by a client * completes. 'result' stores the result code of the entire update procedure. * 'state' specifies the status of the update procedure when this event is * sent. This can be used as a hint by the receiver to determine whether * the update attempt was ever made. In particular, if the state is * dns_clientupdatestate_prepare, the receiver can be sure that the requested * update was not applied. */ typedef struct dns_clientupdateevent { ISC_EVENT_COMMON(struct dns_clientupdateevent); isc_result_t result; dns_clientupdatestate_t state; } dns_clientupdateevent_t; /* too long? */ isc_result_t dns_client_create(dns_client_t **clientp, unsigned int options); isc_result_t dns_client_createx(isc_mem_t *mctx, isc_appctx_t *actx, isc_taskmgr_t *taskmgr, isc_socketmgr_t *socketmgr, isc_timermgr_t *timermgr, unsigned int options, dns_client_t **clientp); isc_result_t dns_client_createx2(isc_mem_t *mctx, isc_appctx_t *actx, isc_taskmgr_t *taskmgr, isc_socketmgr_t *socketmgr, isc_timermgr_t *timermgr, unsigned int options, dns_client_t **clientp, isc_sockaddr_t *localaddr4, isc_sockaddr_t *localaddr6); /*%< * Create a DNS client. These functions create a new client object with * minimal internal resources such as the default 'view' for the IN class and * IPv4/IPv6 dispatches for the view. * * dns_client_createx() takes 'manager' arguments so that the caller can * control the behavior of the client through the underlying event framework. * On the other hand, dns_client_create() simplifies the interface and creates * the managers internally. A DNS client object created via * dns_client_create() is expected to be used by an application that only needs * simple synchronous services or by a thread-based application. * * dns_client_createx2 takes two additional parameters, 'localaddr4' and * 'localaddr6', to specify the local address to use for each 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 other protocol family will not be used. * * If the DNS_CLIENTCREATEOPT_USECACHE flag is set in 'options', * dns_client_create(x) will create a cache database with the view. * * Requires: * *\li 'mctx' is a valid memory context. * *\li 'actx' is a valid application context. * *\li 'taskmgr' is a valid task manager. * *\li 'socketmgr' is a valid socket 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_destroy(dns_client_t **clientp); /*%< * Destroy 'client'. * * 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, 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, 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_setdlv(dns_client_t *client, dns_rdataclass_t rdclass, const char *dlvname); /*%< * Specify a name to use for DNSSEC lookaside validation. * If a trusted key has been added for that name, then DLV will be * used during validation. If 'dlvname' is NULL, then DLV will no * longer be used for this client. * * Requires: * *\li 'client' is a valid client. * * Returns: * *\li #ISC_R_SUCCESS On success. * *\li Anything else Failure. */ isc_result_t dns_client_resolve(dns_client_t *client, 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, 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 typically expected that the client object passed to * dns_client_resolve() was created via dns_client_create() and has its own * managers and contexts. However, if the DNS_CLIENTRESOPT_ALLOWRUN flag is * set in 'options', this function performs the synchronous service even if * it does not have its own manager and context structures. * * 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_cancelresolve(dns_clientrestrans_t *trans); /*%< * Cancel an ongoing resolution procedure started via * dns_client_startresolve(). * * Notes: * *\li If the resolution procedure has not completed, post its CLIENTRESDONE * event with a result code of #ISC_R_CANCELED. * * Requires: * *\li 'trans' is a valid transaction ID. */ void dns_client_destroyrestrans(dns_clientrestrans_t **transp); /*%< * Destroy name resolution transaction state identified by '*transp'. * * Requires: * *\li '*transp' is a valid transaction ID. * *\li The caller has received the CLIENTRESDONE event (either because the * resolution completed or because dns_client_cancelresolve() was called). * * Ensures: * *\li *transp == NULL. */ 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_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. 'keyname' is the DNS name of the key, * and 'keydatabuf' stores the resource data of the key. * * 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_result_t dns_client_request(dns_client_t *client, dns_message_t *qmessage, dns_message_t *rmessage, isc_sockaddr_t *server, unsigned int options, unsigned int parseoptions, dns_tsec_t *tsec, unsigned int timeout, unsigned int udptimeout, unsigned int udpretries); isc_result_t dns_client_startrequest(dns_client_t *client, dns_message_t *qmessage, dns_message_t *rmessage, isc_sockaddr_t *server, unsigned int options, unsigned int parseoptions, dns_tsec_t *tsec, unsigned int timeout, unsigned int udptimeout, unsigned int udpretries, isc_task_t *task, isc_taskaction_t action, void *arg, dns_clientreqtrans_t **transp); /*%< * Send a DNS request containing a query message 'query' to 'server'. * * 'parseoptions' will be used when the response packet is parsed, and will be * passed to dns_message_parse() via dns_request_getresponse(). See * dns_message_parse() for more details. * * 'tsec' is a transaction security object containing, e.g. a TSIG key for * authenticating the request/response transaction. This is optional and can * be NULL, in which case this library performs the transaction without any * transaction authentication. * * 'timeout', 'udptimeout', and 'udpretries' are passed to * dns_request_createvia3(). See dns_request_createvia3() for more details. * * dns_client_request() provides a synchronous service. This function sends * the request and blocks until a response is received. On success, * 'rmessage' will contain the response message. The caller must provide a * valid initialized message. * * It is usually expected that the client object passed to * dns_client_request() was created via dns_client_create() and has its own * managers and contexts. However, if the DNS_CLIENTREQOPT_ALLOWRUN flag is * set in 'options', this function performs the synchronous service even if * it does not have its own manager and context structures. * * dns_client_startrequest() is an asynchronous version of dns_client_request() * and does not block. When the transaction is completed, 'action' will be * called with the argument of a 'dns_clientreqevent_t' object, which contains * the response message (on success). On return, '*transp' is set to an opaque * transaction ID so that the caller can cancel this request. * * DNS_CLIENTREQOPT_TCP switches to the TCP (vs. UDP) transport. * * Requires: * *\li 'client' is a valid client. * *\li 'qmessage' and 'rmessage' are valid initialized message. * *\li 'server' is a valid socket address structure. * *\li 'task' is a valid task. * *\li 'transp' != NULL && *transp == NULL; * * Returns: * *\li #ISC_R_SUCCESS On success. * *\li Anything else Failure. * *\li Any result that dns_message_parse() can return. */ void dns_client_cancelrequest(dns_clientreqtrans_t *transp); /*%< * Cancel an ongoing DNS request procedure started via * dns_client_startrequest(). * * Notes: * *\li If the request procedure has not completed, post its CLIENTREQDONE * event with a result code of #ISC_R_CANCELED. * * Requires: * *\li 'trans' is a valid transaction ID. */ void dns_client_destroyreqtrans(dns_clientreqtrans_t **transp); /*% * Destroy DNS request transaction state identified by '*transp'. * * Requires: * *\li '*transp' is a valid transaction ID. * *\li The caller has received the CLIENTREQDONE event (either because the * request completed or because dns_client_cancelrequest() was called). * * Ensures: * *\li *transp == NULL. */ isc_result_t dns_client_update(dns_client_t *client, dns_rdataclass_t rdclass, dns_name_t *zonename, dns_namelist_t *prerequisites, dns_namelist_t *updates, isc_sockaddrlist_t *servers, dns_tsec_t *tsec, unsigned int options); isc_result_t dns_client_startupdate(dns_client_t *client, dns_rdataclass_t rdclass, dns_name_t *zonename, dns_namelist_t *prerequisites, dns_namelist_t *updates, isc_sockaddrlist_t *servers, dns_tsec_t *tsec, unsigned int options, isc_task_t *task, isc_taskaction_t action, void *arg, dns_clientupdatetrans_t **transp); /*%< * Perform DNS dynamic update for 'updates' of the 'rdclass' class with * optional 'prerequisites'. * * 'updates' are a list of names with associated RRsets to be updated. * * 'prerequisites' are a list of names with associated RRsets corresponding to * the prerequisites of the updates. This is optional and can be NULL, in * which case the prerequisite section of the update message will be empty. * * Both 'updates' and 'prerequisites' must be constructed as specified in * RFC2136. * * 'zonename' is the name of the zone in which the updated names exist. * This is optional and can be NULL. In this case, these functions internally * identify the appropriate zone through some queries for the SOA RR starting * with the first name in prerequisites or updates. * * 'servers' is a list of authoritative servers to which the update message * should be sent. This is optional and can be NULL. In this case, these * functions internally identify the appropriate primary server name and its * addresses through some queries for the SOA RR (like the case of zonename) * and supplemental A/AAAA queries for the server name. * Note: The client module generally assumes the given addresses are of the * primary server of the corresponding zone. It will work even if a secondary * server address is specified as long as the server allows update forwarding, * it is generally discouraged to include secondary server addresses unless * there's strong reason to do so. * * 'tsec' is a transaction security object containing, e.g. a TSIG key for * authenticating the update transaction (and the supplemental query/response * transactions if the server is specified). This is optional and can be * NULL, in which case the library tries the update without any transaction * authentication. * * It is typically expected that the client object passed to * dns_client_update() was created via dns_client_create() and has its own * managers and contexts. However, if the DNS_CLIENTUPDOPT_ALLOWRUN flag is * set in 'options', this function performs the synchronous service even if * it does not have its own manager and context structures. * * dns_client_update() provides a synchronous service. This function blocks * until the entire update procedure completes, including the additional * queries when necessary. * * dns_client_startupdate() is an asynchronous version of dns_client_update(). * It immediately returns (typically with *transp being set to a non-NULL * pointer), and performs the update procedure through a set of internal * events. All transactions including the additional query exchanges are * performed as a separate event, so none of these events cause blocking * operation. When the update procedure completes, the specified function * 'action' will be called with the argument of a 'dns_clientupdateevent_t' * structure. On return, '*transp' is set to an opaque transaction ID so that * the caller can cancel this update process. * * DNS_CLIENTUPDOPT_TCP switches to the TCP (vs. UDP) transport. * * Requires: * *\li 'client' is a valid client. * *\li 'updates' != NULL. * *\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_cancelupdate(dns_clientupdatetrans_t *trans); /*%< * Cancel an ongoing dynamic update procedure started via * dns_client_startupdate(). * * Notes: * *\li If the update procedure has not completed, post its UPDATEDONE * event with a result code of #ISC_R_CANCELED. * * Requires: * *\li 'trans' is a valid transaction ID. */ void dns_client_destroyupdatetrans(dns_clientupdatetrans_t **transp); /*%< * Destroy dynamic update transaction identified by '*transp'. * * Requires: * *\li '*transp' is a valid transaction ID. * *\li The caller has received the UPDATEDONE event (either because the * update completed or because dns_client_cancelupdate() was called). * * Ensures: * *\li *transp == NULL. */ isc_result_t dns_client_updaterec(dns_client_updateop_t op, dns_name_t *owner, dns_rdatatype_t type, dns_rdata_t *source, dns_ttl_t ttl, dns_name_t *target, dns_rdataset_t *rdataset, dns_rdatalist_t *rdatalist, dns_rdata_t *rdata, isc_mem_t *mctx); /*%< * TBD */ void dns_client_freeupdate(dns_name_t **namep); /*%< * TBD */ isc_mem_t * dns_client_mctx(dns_client_t *client); ISC_LANG_ENDDECLS #endif /* DNS_CLIENT_H */
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