2 * util/module.h - DNS handling module interface
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39 * This file contains the interface for DNS handling modules.
41 * The module interface uses the DNS modules as state machines. The
42 * state machines are activated in sequence to operate on queries. Once
43 * they are done, the reply is passed back. In the usual setup the mesh
44 * is the caller of the state machines and once things are done sends replies
45 * and invokes result callbacks.
47 * The module provides a number of functions, listed in the module_func_block.
48 * The module is inited and destroyed and memory usage queries, for the
49 * module as a whole, for entire-module state (such as a cache). And per-query
50 * functions are called, operate to move the state machine and cleanup of
51 * the per-query state.
53 * Most per-query state should simply be allocated in the query region.
54 * This is destroyed at the end of the query.
56 * The module environment contains services and information and caches
57 * shared by the modules and the rest of the system. It also contains
58 * function pointers for module-specific tasks (like sending queries).
60 * *** Example module calls for a normal query
62 * In this example, the query does not need recursion, all the other data
63 * can be found in the cache. This makes the example shorter.
65 * At the start of the program the iterator module is initialised.
66 * The iterator module sets up its global state, such as donotquery lists
67 * and private address trees.
69 * A query comes in, and a mesh entry is created for it. The mesh
70 * starts the resolution process. The validator module is the first
71 * in the list of modules, and it is started on this new query. The
72 * operate() function is called. The validator decides it needs not do
73 * anything yet until there is a result and returns wait_module, that
74 * causes the next module in the list to be started.
76 * The next module is the iterator. It is started on the passed query and
77 * decides to perform a lookup. For this simple example, the delegation
78 * point information is available, and all the iterator wants to do is
79 * send a UDP query. The iterator uses env.send_query() to send the
80 * query. Then the iterator suspends (returns from the operate call).
82 * When the UDP reply comes back (and on errors and timeouts), the
83 * operate function is called for the query, on the iterator module,
84 * with the event that there is a reply. The iterator decides that this
85 * is enough, the work is done. It returns the value finished from the
86 * operate call, which causes the previous module to be started.
88 * The previous module, the validator module, is started with the event
89 * that the iterator module is done. The validator decides to validate
90 * the query. Once it is done (which could take recursive lookups, but
91 * in this example no recursive lookups are needed), it returns from the
92 * operate function with finished.
94 * There is no previous module from the validator module, and the mesh
95 * takes this to mean that the query is finally done. The mesh invokes
96 * callbacks and sends packets to queriers.
98 * If other modules had been waiting (recursively) on the answer to this
99 * query, then the mesh will tell them about it. It calls the inform_super
100 * routine on all the waiting modules, and once that is done it calls all of
101 * them with the operate() call. During inform_super the query that is done
102 * still exists and information can be copied from it (but the module should
103 * not really re-entry codepoints and services). During the operate call
104 * the modules can use stored state to continue operation with the results.
105 * (network buffers are used to contain the answer packet during the
106 * inform_super phase, but after that the network buffers will be cleared
107 * of their contents so that other tasks can be performed).
109 * *** Example module calls for recursion
111 * A module is called in operate, and it decides that it wants to perform
112 * recursion. That is, it wants the full state-machine-list to operate on
113 * a different query. It calls env.attach_sub() to create a new query state.
114 * The routine returns the newly created state, and potentially the module
115 * can edit the module-states for the newly created query (i.e. pass along
116 * some information, like delegation points). The module then suspends,
117 * returns from the operate routine.
119 * The mesh meanwhile will have the newly created query (or queries) on
120 * a waiting list, and will call operate() on this query (or queries).
121 * It starts again at the start of the module list for them. The query
122 * (or queries) continue to operate their state machines, until they are
123 * done. When they are done the mesh calls inform_super on the module that
124 * wanted the recursion. After that the mesh calls operate() on the module
125 * that wanted to do the recursion, and during this phase the module could,
126 * for example, decide to create more recursions.
128 * If the module decides it no longer wants the recursive information
129 * it can call detach_subs. Those queries will still run to completion,
130 * potentially filling the cache with information. Inform_super is not
133 * The iterator module will fetch items from the cache, so a recursion
134 * attempt may complete very quickly if the item is in cache. The calling
135 * module has to wait for completion or eventual timeout. A recursive query
136 * that times out returns a servfail rcode (servfail is also returned for
137 * other errors during the lookup).
139 * Results are passed in the qstate, the rcode member is used to pass
140 * errors without requiring memory allocation, so that the code can continue
141 * in out-of-memory conditions. If the rcode member is 0 (NOERROR) then
142 * the dns_msg entry contains a filled out message. This message may
143 * also contain an rcode that is nonzero, but in this case additional
144 * information (query, additional) can be passed along.
146 * The rcode and dns_msg are used to pass the result from the the rightmost
147 * module towards the leftmost modules and then towards the user.
149 * If you want to avoid recursion-cycles where queries need other queries
150 * that need the first one, use detect_cycle() to see if that will happen.
154 #ifndef UTIL_MODULE_H
155 #define UTIL_MODULE_H
156 #include "util/storage/lruhash.h"
157 #include "util/data/msgreply.h"
158 #include "util/data/msgparse.h"
171 struct outside_network;
172 struct module_qstate;
177 struct val_neg_cache;
178 struct iter_forwards;
181 struct respip_client_info;
182 struct respip_addr_info;
184 /** Maximum number of modules in operation */
185 #define MAX_MODULE 16
187 /** Maximum number of known edns options */
188 #define MAX_KNOWN_EDNS_OPTS 256
190 enum inplace_cb_list_type {
191 /* Inplace callbacks for when a resolved reply is ready to be sent to the
193 inplace_cb_reply = 0,
194 /* Inplace callbacks for when a reply is given from the cache. */
195 inplace_cb_reply_cache,
196 /* Inplace callbacks for when a reply is given with local data
197 * (or Chaos reply). */
198 inplace_cb_reply_local,
199 /* Inplace callbacks for when the reply is servfail. */
200 inplace_cb_reply_servfail,
201 /* Inplace callbacks for when a query is ready to be sent to the back.*/
203 /* Inplace callback for when a reply is received from the back. */
204 inplace_cb_query_response,
205 /* Inplace callback for when EDNS is parsed on a reply received from the
207 inplace_cb_edns_back_parsed,
208 /* Total number of types. Used for array initialization.
209 * Should always be last. */
210 inplace_cb_types_total
214 /** Known edns option. Can be populated during modules' init. */
215 struct edns_known_option {
216 /** type of this edns option */
218 /** whether the option needs to bypass the cache stage */
219 int bypass_cache_stage;
220 /** whether the option needs mesh aggregation */
225 * Inplace callback list of registered routines to be called.
229 struct inplace_cb* next;
230 /** Inplace callback routine */
238 * Inplace callback function called before replying.
239 * Called as func(edns, qstate, opt_list_out, qinfo, reply_info, rcode,
240 * region, python_callback)
242 * qinfo: the query info.
243 * qstate: the module state. NULL when calling before the query reaches the
245 * rep: reply_info. Could be NULL.
246 * rcode: the return code.
247 * edns: the edns_data of the reply. When qstate is NULL, it is also used as
249 * opt_list_out: the edns options list for the reply.
250 * region: region to store data.
251 * python_callback: only used for registering a python callback function.
253 typedef int inplace_cb_reply_func_type(struct query_info* qinfo,
254 struct module_qstate* qstate, struct reply_info* rep, int rcode,
255 struct edns_data* edns, struct edns_option** opt_list_out,
256 struct regional* region, int id, void* callback);
259 * Inplace callback function called before sending the query to a nameserver.
260 * Called as func(qinfo, flags, qstate, addr, addrlen, zone, zonelen, region,
264 * flags: flags of the query.
265 * qstate: query state.
266 * addr: to which server to send the query.
267 * addrlen: length of addr.
268 * zone: name of the zone of the delegation point. wireformat dname.
269 * This is the delegation point name for which the server is deemed
271 * zonelen: length of zone.
272 * region: region to store data.
273 * python_callback: only used for registering a python callback function.
275 typedef int inplace_cb_query_func_type(struct query_info* qinfo, uint16_t flags,
276 struct module_qstate* qstate, struct sockaddr_storage* addr,
277 socklen_t addrlen, uint8_t* zone, size_t zonelen, struct regional* region,
278 int id, void* callback);
281 * Inplace callback function called after parsing edns on query reply.
282 * Called as func(qstate, cb_args)
284 * qstate: the query state
286 * cb_args: argument passed when registering callback.
288 typedef int inplace_cb_edns_back_parsed_func_type(struct module_qstate* qstate,
289 int id, void* cb_args);
292 * Inplace callback function called after parsing query response.
293 * Called as func(qstate, id, cb_args)
295 * qstate: the query state
296 * response: query response
298 * cb_args: argument passed when registering callback.
300 typedef int inplace_cb_query_response_func_type(struct module_qstate* qstate,
301 struct dns_msg* response, int id, void* cb_args);
304 * Module environment.
305 * Services and data provided to the module.
309 /** config file with config options */
310 struct config_file* cfg;
311 /** shared message cache */
312 struct slabhash* msg_cache;
313 /** shared rrset cache */
314 struct rrset_cache* rrset_cache;
315 /** shared infrastructure cache (edns, lameness) */
316 struct infra_cache* infra_cache;
317 /** shared key cache */
318 struct key_cache* key_cache;
320 /* --- services --- */
322 * Send serviced DNS query to server. UDP/TCP and EDNS is handled.
323 * operate() should return with wait_reply. Later on a callback
324 * will cause operate() to be called with event timeout or reply.
325 * The time until a timeout is calculated from roundtrip timing,
326 * several UDP retries are attempted.
327 * @param qinfo: query info.
328 * @param flags: host order flags word, with opcode and CD bit.
329 * @param dnssec: if set, EDNS record will have bits set.
330 * If EDNS_DO bit is set, DO bit is set in EDNS records.
331 * If BIT_CD is set, CD bit is set in queries with EDNS records.
332 * @param want_dnssec: if set, the validator wants DNSSEC. Without
333 * EDNS, the answer is likely to be useless for this domain.
334 * @param nocaps: do not use caps_for_id, use the qname as given.
335 * (ignored if caps_for_id is disabled).
336 * @param addr: where to.
337 * @param addrlen: length of addr.
338 * @param zone: delegation point name.
339 * @param zonelen: length of zone name.
340 * @param ssl_upstream: use SSL for upstream queries.
341 * @param tls_auth_name: if ssl_upstream, use this name with TLS
343 * @param q: wich query state to reactivate upon return.
344 * @return: false on failure (memory or socket related). no query was
345 * sent. Or returns an outbound entry with qsent and qstate set.
346 * This outbound_entry will be used on later module invocations
347 * that involve this query (timeout, error or reply).
349 struct outbound_entry* (*send_query)(struct query_info* qinfo,
350 uint16_t flags, int dnssec, int want_dnssec, int nocaps,
351 struct sockaddr_storage* addr, socklen_t addrlen,
352 uint8_t* zone, size_t zonelen, int ssl_upstream,
353 char* tls_auth_name, struct module_qstate* q);
357 * Remove all sub-query references from this query state.
358 * Keeps super-references of those sub-queries correct.
359 * Updates stat items in mesh_area structure.
360 * @param qstate: used to find mesh state.
362 void (*detach_subs)(struct module_qstate* qstate);
366 * Creates it if it does not exist already.
367 * Keeps sub and super references correct.
368 * Updates stat items in mesh_area structure.
369 * Pass if it is priming query or not.
371 * o if error (malloc) happened.
372 * o need to initialise the new state (module init; it is a new state).
373 * so that the next run of the query with this module is successful.
374 * o no init needed, attachment successful.
376 * @param qstate: the state to find mesh state, and that wants to
377 * receive the results from the new subquery.
378 * @param qinfo: what to query for (copied).
379 * @param qflags: what flags to use (RD, CD flag or not).
380 * @param prime: if it is a (stub) priming query.
381 * @param valrec: validation lookup recursion, does not need validation
382 * @param newq: If the new subquery needs initialisation, it is
383 * returned, otherwise NULL is returned.
384 * @return: false on error, true if success (and init may be needed).
386 int (*attach_sub)(struct module_qstate* qstate,
387 struct query_info* qinfo, uint16_t qflags, int prime,
388 int valrec, struct module_qstate** newq);
391 * Add detached query.
392 * Creates it if it does not exist already.
393 * Does not make super/sub references.
394 * Performs a cycle detection - for double check - and fails if there is
396 * Updates stat items in mesh_area structure.
397 * Pass if it is priming query or not.
399 * o if error (malloc) happened.
400 * o need to initialise the new state (module init; it is a new state).
401 * so that the next run of the query with this module is successful.
402 * o no init needed, attachment successful.
403 * o added subquery, created if it did not exist already.
405 * @param qstate: the state to find mesh state, and that wants to receive
406 * the results from the new subquery.
407 * @param qinfo: what to query for (copied).
408 * @param qflags: what flags to use (RD / CD flag or not).
409 * @param prime: if it is a (stub) priming query.
410 * @param valrec: if it is a validation recursion query (lookup of key, DS).
411 * @param newq: If the new subquery needs initialisation, it is returned,
412 * otherwise NULL is returned.
413 * @param sub: The added mesh state, created if it did not exist already.
414 * @return: false on error, true if success (and init may be needed).
416 int (*add_sub)(struct module_qstate* qstate,
417 struct query_info* qinfo, uint16_t qflags, int prime,
418 int valrec, struct module_qstate** newq,
419 struct mesh_state** sub);
422 * Kill newly attached sub. If attach_sub returns newq for
423 * initialisation, but that fails, then this routine will cleanup and
424 * delete the freshly created sub.
425 * @param newq: the new subquery that is no longer needed.
428 void (*kill_sub)(struct module_qstate* newq);
431 * Detect if adding a dependency for qstate on name,type,class will
432 * create a dependency cycle.
433 * @param qstate: given mesh querystate.
434 * @param qinfo: query info for dependency.
435 * @param flags: query flags of dependency, RD/CD flags.
436 * @param prime: if dependency is a priming query or not.
437 * @param valrec: validation lookup recursion, does not need validation
438 * @return true if the name,type,class exists and the given
439 * qstate mesh exists as a dependency of that name. Thus
440 * if qstate becomes dependent on name,type,class then a
443 int (*detect_cycle)(struct module_qstate* qstate,
444 struct query_info* qinfo, uint16_t flags, int prime,
447 /** region for temporary usage. May be cleared after operate() call. */
448 struct regional* scratch;
449 /** buffer for temporary usage. May be cleared after operate() call. */
450 struct sldns_buffer* scratch_buffer;
451 /** internal data for daemon - worker thread. */
452 struct worker* worker;
453 /** the worker event base */
454 struct comm_base* worker_base;
455 /** the outside network */
456 struct outside_network* outnet;
457 /** mesh area with query state dependencies */
458 struct mesh_area* mesh;
459 /** allocation service */
460 struct alloc_cache* alloc;
461 /** random table to generate random numbers */
462 struct ub_randstate* rnd;
463 /** time in seconds, converted to integer */
465 /** time in microseconds. Relatively recent. */
466 struct timeval* now_tv;
467 /** is validation required for messages, controls client-facing
468 * validation status (AD bits) and servfails */
469 int need_to_validate;
470 /** trusted key storage; these are the configured keys, if not NULL,
471 * otherwise configured by validator. These are the trust anchors,
472 * and are not primed and ready for validation, but on the bright
473 * side, they are read only memory, thus no locks and fast. */
474 struct val_anchors* anchors;
475 /** negative cache, configured by the validator. if not NULL,
476 * contains NSEC record lookup trees. */
477 struct val_neg_cache* neg_cache;
478 /** the 5011-probe timer (if any) */
479 struct comm_timer* probe_timer;
481 struct auth_zones* auth_zones;
482 /** Mapping of forwarding zones to targets.
483 * iterator forwarder information. per-thread, created by worker */
484 struct iter_forwards* fwds;
486 * iterator forwarder information. per-thread, created by worker.
487 * The hints -- these aren't stored in the cache because they don't
488 * expire. The hints are always used to "prime" the cache. Note
489 * that both root hints and stub zone "hints" are stored in this
492 struct iter_hints* hints;
493 /** module specific data. indexed by module id. */
494 void* modinfo[MAX_MODULE];
496 /* Shared linked list of inplace callback functions */
497 struct inplace_cb* inplace_cb_lists[inplace_cb_types_total];
500 * Shared array of known edns options (size MAX_KNOWN_EDNS_OPTS).
501 * Filled by edns literate modules during init.
503 struct edns_known_option* edns_known_options;
504 /* Number of known edns options */
505 size_t edns_known_options_num;
507 /* Make every mesh state unique, do not aggregate mesh states. */
512 * External visible states of the module state machine
513 * Modules may also have an internal state.
514 * Modules are supposed to run to completion or until blocked.
516 enum module_ext_state {
517 /** initial state - new query */
518 module_state_initial = 0,
519 /** waiting for reply to outgoing network query */
521 /** module is waiting for another module */
523 /** module is waiting for another module; that other is restarted */
525 /** module is waiting for sub-query */
526 module_wait_subquery,
527 /** module could not finish the query */
529 /** module is finished with query */
534 * Events that happen to modules, that start or wakeup modules.
538 module_event_new = 0,
539 /** query passed by other module */
541 /** reply inbound from server */
543 /** no reply, timeout or other error */
544 module_event_noreply,
545 /** reply is there, but capitalisation check failed */
546 module_event_capsfail,
547 /** next module is done, and its reply is awaiting you */
548 module_event_moddone,
554 * Linked list of sockaddrs
555 * May be allocated such that only 'len' bytes of addr exist for the structure.
559 struct sock_list* next;
560 /** length of addr */
563 struct sockaddr_storage addr;
566 struct respip_action_info;
569 * Module state, per query.
571 struct module_qstate {
572 /** which query is being answered: name, type, class */
573 struct query_info qinfo;
574 /** flags uint16 from query */
575 uint16_t query_flags;
576 /** if this is a (stub or root) priming query (with hints) */
578 /** if this is a validation recursion query that does not get
579 * validation itself */
582 /** comm_reply contains server replies */
583 struct comm_reply* reply;
584 /** the reply message, with message for client and calling module */
585 struct dns_msg* return_msg;
586 /** the rcode, in case of error, instead of a reply message */
588 /** origin of the reply (can be NULL from cache, list for cnames) */
589 struct sock_list* reply_origin;
590 /** IP blacklist for queries */
591 struct sock_list* blacklist;
592 /** region for this query. Cleared when query process finishes. */
593 struct regional* region;
594 /** failure reason information if val-log-level is high */
595 struct config_strlist* errinf;
597 /** which module is executing */
600 enum module_ext_state ext_state[MAX_MODULE];
601 /** module specific data for query. indexed by module id. */
602 void* minfo[MAX_MODULE];
603 /** environment for this query */
604 struct module_env* env;
605 /** mesh related information for this query */
606 struct mesh_state* mesh_info;
607 /** how many seconds before expiry is this prefetched (0 if not) */
608 time_t prefetch_leeway;
610 /** incoming edns options from the front end */
611 struct edns_option* edns_opts_front_in;
612 /** outgoing edns options to the back end */
613 struct edns_option* edns_opts_back_out;
614 /** incoming edns options from the back end */
615 struct edns_option* edns_opts_back_in;
616 /** outgoing edns options to the front end */
617 struct edns_option* edns_opts_front_out;
618 /** whether modules should answer from the cache */
620 /** whether modules should store answer in the cache */
622 /** whether to refetch a fresh answer on finishing this state*/
626 * Attributes of clients that share the qstate that may affect IP-based
629 struct respip_client_info* client_info;
631 /** Extended result of response-ip action processing, mainly
632 * for logging purposes. */
633 struct respip_action_info* respip_action_info;
635 /** whether the reply should be dropped */
640 * Module functionality block
642 struct module_func_block {
643 /** text string name of module */
647 * init the module. Called once for the global state.
648 * This is the place to apply settings from the config file.
649 * @param env: module environment.
650 * @param id: module id number.
653 int (*init)(struct module_env* env, int id);
656 * de-init, delete, the module. Called once for the global state.
657 * @param env: module environment.
658 * @param id: module id number.
660 void (*deinit)(struct module_env* env, int id);
663 * accept a new query, or work further on existing query.
664 * Changes the qstate->ext_state to be correct on exit.
665 * @param ev: event that causes the module state machine to
667 * @param qstate: the query state.
668 * Note that this method is not allowed to change the
669 * query state 'identity', that is query info, qflags,
670 * and priming status.
671 * Attach a subquery to get results to a different query.
672 * @param id: module id number that operate() is called on.
673 * @param outbound: if not NULL this event is due to the reply/timeout
674 * or error on this outbound query.
675 * @return: if at exit the ext_state is:
676 * o wait_module: next module is started. (with pass event).
677 * o error or finished: previous module is resumed.
678 * o otherwise it waits until that event happens (assumes
679 * the service routine to make subrequest or send message
682 void (*operate)(struct module_qstate* qstate, enum module_ev event,
683 int id, struct outbound_entry* outbound);
686 * inform super querystate about the results from this subquerystate.
687 * Is called when the querystate is finished. The method invoked is
688 * the one from the current module active in the super querystate.
689 * @param qstate: the query state that is finished.
690 * Examine return_rcode and return_reply in the qstate.
691 * @param id: module id for this module.
692 * This coincides with the current module for the super qstate.
693 * @param super: the super querystate that needs to be informed.
695 void (*inform_super)(struct module_qstate* qstate, int id,
696 struct module_qstate* super);
699 * clear module specific data
701 void (*clear)(struct module_qstate* qstate, int id);
704 * How much memory is the module specific data using.
705 * @param env: module environment.
706 * @param id: the module id.
707 * @return the number of bytes that are alloced.
709 size_t (*get_mem)(struct module_env* env, int id);
713 * Debug utility: module external qstate to string
714 * @param s: the state value.
715 * @return descriptive string.
717 const char* strextstate(enum module_ext_state s);
720 * Debug utility: module event to string
721 * @param e: the module event value.
722 * @return descriptive string.
724 const char* strmodulevent(enum module_ev e);
727 * Initialize the edns known options by allocating the required space.
728 * @param env: the module environment.
729 * @return false on failure (no memory).
731 int edns_known_options_init(struct module_env* env);
734 * Free the allocated space for the known edns options.
735 * @param env: the module environment.
737 void edns_known_options_delete(struct module_env* env);
740 * Register a known edns option. Overwrite the flags if it is already
741 * registered. Used before creating workers to register known edns options.
742 * @param opt_code: the edns option code.
743 * @param bypass_cache_stage: whether the option interacts with the cache.
744 * @param no_aggregation: whether the option implies more specific
746 * @param env: the module environment.
747 * @return true on success, false on failure (registering more options than
748 * allowed or trying to register after the environment is copied to the
751 int edns_register_option(uint16_t opt_code, int bypass_cache_stage,
752 int no_aggregation, struct module_env* env);
755 * Register an inplace callback function.
756 * @param cb: pointer to the callback function.
757 * @param type: inplace callback type.
758 * @param cbarg: argument for the callback function, or NULL.
759 * @param env: the module environment.
760 * @param id: module id.
761 * @return true on success, false on failure (out of memory or trying to
762 * register after the environment is copied to the threads.)
765 inplace_cb_register(void* cb, enum inplace_cb_list_type type, void* cbarg,
766 struct module_env* env, int id);
769 * Delete callback for specified type and module id.
770 * @param env: the module environment.
771 * @param type: inplace callback type.
772 * @param id: module id.
775 inplace_cb_delete(struct module_env* env, enum inplace_cb_list_type type,
779 * Delete all the inplace callback linked lists.
780 * @param env: the module environment.
782 void inplace_cb_lists_delete(struct module_env* env);
785 * Check if an edns option is known.
786 * @param opt_code: the edns option code.
787 * @param env: the module environment.
788 * @return pointer to registered option if the edns option is known,
791 struct edns_known_option* edns_option_is_known(uint16_t opt_code,
792 struct module_env* env);
795 * Check if an edns option needs to bypass the reply from cache stage.
796 * @param list: the edns options.
797 * @param env: the module environment.
798 * @return true if an edns option needs to bypass the cache stage,
801 int edns_bypass_cache_stage(struct edns_option* list,
802 struct module_env* env);
805 * Check if an unique mesh state is required. Might be triggered by EDNS option
806 * or set for the complete env.
807 * @param list: the edns options.
808 * @param env: the module environment.
809 * @return true if an edns option needs a unique mesh state,
812 int unique_mesh_state(struct edns_option* list, struct module_env* env);
815 * Log the known edns options.
816 * @param level: the desired verbosity level.
817 * @param env: the module environment.
819 void log_edns_known_options(enum verbosity_value level,
820 struct module_env* env);
822 #endif /* UTIL_MODULE_H */