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Diffstat (limited to 'contrib/unbound/services/mesh.h')
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diff --git a/contrib/unbound/services/mesh.h b/contrib/unbound/services/mesh.h new file mode 100644 index 000000000000..f19f423a8cd3 --- /dev/null +++ b/contrib/unbound/services/mesh.h @@ -0,0 +1,726 @@ +/* + * services/mesh.h - deal with mesh of query states and handle events for that. + * + * Copyright (c) 2007, NLnet Labs. All rights reserved. + * + * This software is open source. + *  + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + *  + * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + *  + * Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + *  + * Neither the name of the NLNET LABS nor the names of its contributors may + * be used to endorse or promote products derived from this software without + * specific prior written permission. + *  + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED + * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/** + * \file + * + * This file contains functions to assist in dealing with a mesh of + * query states. This mesh is supposed to be thread-specific. + * It consists of query states (per qname, qtype, qclass) and connections + * between query states and the super and subquery states, and replies to + * send back to clients. + */ + +#ifndef SERVICES_MESH_H +#define SERVICES_MESH_H + +#include "util/rbtree.h" +#include "util/netevent.h" +#include "util/data/msgparse.h" +#include "util/module.h" +#include "services/modstack.h" +#include "services/rpz.h" +#include "libunbound/unbound.h" +struct sldns_buffer; +struct mesh_state; +struct mesh_reply; +struct mesh_cb; +struct query_info; +struct reply_info; +struct outbound_entry; +struct timehist; +struct respip_client_info; + +/** + * Maximum number of mesh state activations. Any more is likely an + * infinite loop in the module. It is then terminated. + */ +#define MESH_MAX_ACTIVATION 10000 + +/** + * Max number of references-to-references-to-references.. search size. + * Any more is treated like 'too large', and the creation of a new + * dependency is failed (so that no loops can be created). + */ +#define MESH_MAX_SUBSUB 1024 + +/**  + * Mesh of query states + */ +struct mesh_area { +	/** active module stack */ +	struct module_stack mods; +	/** environment for new states */ +	struct module_env* env; + +	/** set of runnable queries (mesh_state.run_node) */ +	rbtree_type run; +	/** rbtree of all current queries (mesh_state.node)*/ +	rbtree_type all; + +	/** number of queries for unbound's auth_zones, upstream query */ +	size_t num_query_authzone_up; +	/** number of queries for unbound's auth_zones, downstream answers */ +	size_t num_query_authzone_down; + +	/** count of the total number of mesh_reply entries */ +	size_t num_reply_addrs; +	/** count of the number of mesh_states that have mesh_replies  +	 * Because a state can send results to multiple reply addresses, +	 * this number must be equal or lower than num_reply_addrs. */ +	size_t num_reply_states; +	/** number of mesh_states that have no mesh_replies, and also +	 * an empty set of super-states, thus are 'toplevel' or detached +	 * internal opportunistic queries */ +	size_t num_detached_states; +	/** number of reply states in the forever list */ +	size_t num_forever_states; + +	/** max total number of reply states to have */ +	size_t max_reply_states; +	/** max forever number of reply states to have */ +	size_t max_forever_states; + +	/** stats, cumulative number of reply states jostled out */ +	size_t stats_jostled; +	/** stats, cumulative number of incoming client msgs dropped */ +	size_t stats_dropped; +	/** stats, number of expired replies sent */ +	size_t ans_expired; +	/** stats, number of cached replies from cachedb */ +	size_t ans_cachedb; +	/** number of replies sent */ +	size_t replies_sent; +	/** sum of waiting times for the replies */ +	struct timeval replies_sum_wait; +	/** histogram of time values */ +	struct timehist* histogram; +	/** (extended stats) secure replies */ +	size_t ans_secure; +	/** (extended stats) bogus replies */ +	size_t ans_bogus; +	/** (extended stats) number of validation operations */ +	size_t val_ops; +	/** (extended stats) rcodes in replies */ +	size_t ans_rcode[UB_STATS_RCODE_NUM]; +	/** (extended stats) rcode nodata in replies */ +	size_t ans_nodata; +	/** (extended stats) type of applied RPZ action */ +	size_t rpz_action[UB_STATS_RPZ_ACTION_NUM]; +	/** stats, number of queries removed due to discard-timeout */ +	size_t num_queries_discard_timeout; +	/** stats, number of queries removed due to wait-limit */ +	size_t num_queries_wait_limit; +	/** stats, number of dns error reports generated */ +	size_t num_dns_error_reports; + +	/** backup of query if other operations recurse and need the +	 * network buffers */ +	struct sldns_buffer* qbuf_bak; + +	/** double linked list of the run-to-completion query states. +	 * These are query states with a reply */ +	struct mesh_state* forever_first; +	/** last entry in run forever list */ +	struct mesh_state* forever_last; + +	/** double linked list of the query states that can be jostled out +	 * by new queries if too old.  These are query states with a reply */ +	struct mesh_state* jostle_first; +	/** last entry in jostle list - this is the entry that is newest */ +	struct mesh_state* jostle_last; +	/** timeout for jostling. if age is lower, it does not get jostled. */ +	struct timeval jostle_max; + +	/** If we need to use response ip (value passed from daemon)*/ +	int use_response_ip; +	/** If we need to use RPZ (value passed from daemon) */ +	int use_rpz; +}; + +/** + * A mesh query state + * Unique per qname, qtype, qclass (from the qstate). + * And RD / CD flag; in case a client turns it off. + * And priming queries are different from ordinary queries (because of hints). + * + * The entire structure is allocated in a region, this region is the qstate + * region. All parts (rbtree nodes etc) are also allocated in the region. + */ +struct mesh_state { +	/** node in mesh_area all tree, key is this struct. Must be first. */ +	rbnode_type node; +	/** node in mesh_area runnable tree, key is this struct */ +	rbnode_type run_node; +	/** the query state. Note that the qinfo and query_flags  +	 * may not change. */ +	struct module_qstate s; +	/** the list of replies to clients for the results */ +	struct mesh_reply* reply_list; +	/** the list of callbacks for the results */ +	struct mesh_cb* cb_list; +	/** set of superstates (that want this state's result)  +	 * contains struct mesh_state_ref* */ +	rbtree_type super_set; +	/** set of substates (that this state needs to continue) +	 * contains struct mesh_state_ref* */ +	rbtree_type sub_set; +	/** number of activations for the mesh state */ +	size_t num_activated; + +	/** previous in linked list for reply states */ +	struct mesh_state* prev; +	/** next in linked list for reply states */ +	struct mesh_state* next; +	/** if this state is in the forever list, jostle list, or neither */ +	enum mesh_list_select { mesh_no_list, mesh_forever_list,  +		mesh_jostle_list } list_select; +	/** pointer to this state for uniqueness or NULL */ +	struct mesh_state* unique; + +	/** true if replies have been sent out (at end for alignment) */ +	uint8_t replies_sent; +}; + +/** + * Rbtree reference to a mesh_state. + * Used in super_set and sub_set.  + */ +struct mesh_state_ref { +	/** node in rbtree for set, key is this structure */ +	rbnode_type node; +	/** the mesh state */ +	struct mesh_state* s; +}; + +/** + * Reply to a client + */ +struct mesh_reply { +	/** next in reply list */ +	struct mesh_reply* next; +	/** the query reply destination, packet buffer and where to send. */ +	struct comm_reply query_reply; +	/** edns data from query */ +	struct edns_data edns; +	/** the time when request was entered */ +	struct timeval start_time; +	/** id of query, in network byteorder. */ +	uint16_t qid; +	/** flags of query, for reply flags */ +	uint16_t qflags; +	/** qname from this query. len same as mesh qinfo. */ +	uint8_t* qname; +	/** same as that in query_info. */ +	struct local_rrset* local_alias; +	/** send query to this http2 stream, if set */ +	struct http2_stream* h2_stream; +}; + +/**  + * Mesh result callback func. + * called as func(cb_arg, rcode, buffer_with_reply, security, why_bogus, + *		was_ratelimited); + */ +typedef void (*mesh_cb_func_type)(void* cb_arg, int rcode, struct sldns_buffer*, +	enum sec_status, char* why_bogus, int was_ratelimited); + +/** + * Callback to result routine + */ +struct mesh_cb { +	/** next in list */ +	struct mesh_cb* next; +	/** edns data from query */ +	struct edns_data edns; +	/** id of query, in network byteorder. */ +	uint16_t qid; +	/** flags of query, for reply flags */ +	uint16_t qflags; +	/** buffer for reply */ +	struct sldns_buffer* buf; +	/** callback routine for results. if rcode != 0 buf has message. +	 * called as cb(cb_arg, rcode, buf, sec_state, why_bogus, was_ratelimited); +	 */ +	mesh_cb_func_type cb; +	/** user arg for callback */ +	void* cb_arg; +}; + +/* ------------------- Functions for worker -------------------- */ + +/** + * Allocate mesh, to empty. + * @param stack: module stack to activate, copied (as readonly reference). + * @param env: environment for new queries. + * @return mesh: the new mesh or NULL on error. + */ +struct mesh_area* mesh_create(struct module_stack* stack,  +	struct module_env* env); + +/** + * Delete mesh, and all query states and replies in it. + * @param mesh: the mesh to delete. + */ +void mesh_delete(struct mesh_area* mesh); + +/** + * New query incoming from clients. Create new query state if needed, and + * add mesh_reply to it. Returns error to client on malloc failures. + * Will run the mesh area queries to process if a new query state is created. + * + * @param mesh: the mesh. + * @param qinfo: query from client. + * @param cinfo: additional information associated with the query client. + * 	'cinfo' itself is ephemeral but data pointed to by its members + *      can be assumed to be valid and unchanged until the query processing is + *      completed. + * @param qflags: flags from client query. + * @param edns: edns data from client query. + * @param rep: where to reply to. + * @param qid: query id to reply with. + * @param rpz_passthru: if true, the rpz passthru was previously found and + * 	further rpz processing is stopped. + */ +void mesh_new_client(struct mesh_area* mesh, struct query_info* qinfo, +	struct respip_client_info* cinfo, uint16_t qflags, +	struct edns_data* edns, struct comm_reply* rep, uint16_t qid, +	int rpz_passthru); + +/** + * New query with callback. Create new query state if needed, and + * add mesh_cb to it.  + * Will run the mesh area queries to process if a new query state is created. + * + * @param mesh: the mesh. + * @param qinfo: query from client. + * @param qflags: flags from client query. + * @param edns: edns data from client query. + * @param buf: buffer for reply contents. + * @param qid: query id to reply with. + * @param cb: callback function. + * @param cb_arg: callback user arg. + * @param rpz_passthru: if true, the rpz passthru was previously found and + * 	further rpz processing is stopped. + * @return 0 on error. + */ +int mesh_new_callback(struct mesh_area* mesh, struct query_info* qinfo, +	uint16_t qflags, struct edns_data* edns, struct sldns_buffer* buf,  +	uint16_t qid, mesh_cb_func_type cb, void* cb_arg, int rpz_passthru); + +/** + * New prefetch message. Create new query state if needed. + * Will run the mesh area queries to process if a new query state is created. + * + * @param mesh: the mesh. + * @param qinfo: query from client. + * @param qflags: flags from client query. + * @param leeway: TTL leeway what to expire earlier for this update. + * @param rpz_passthru: if true, the rpz passthru was previously found and + * 	further rpz processing is stopped. + * @param addr: sockaddr_storage for the client; to be used with subnet. + * @param opt_list: edns opt_list from the client; to be used when subnet is + *	enabled. + */ +void mesh_new_prefetch(struct mesh_area* mesh, struct query_info* qinfo, +	uint16_t qflags, time_t leeway, int rpz_passthru, +	struct sockaddr_storage* addr, struct edns_option* opt_list); + +/** + * Handle new event from the wire. A serviced query has returned. + * The query state will be made runnable, and the mesh_area will process + * query states until processing is complete. + * + * @param mesh: the query mesh. + * @param e: outbound entry, with query state to run and reply pointer. + * @param reply: the comm point reply info. + * @param what: NETEVENT_* error code (if not 0, what is wrong, TIMEOUT). + */ +void mesh_report_reply(struct mesh_area* mesh, struct outbound_entry* e, +	struct comm_reply* reply, int what); + +/* ------------------- Functions for module environment --------------- */ + +/** + * Detach-subqueries. + * Remove all sub-query references from this query state. + * Keeps super-references of those sub-queries correct. + * Updates stat items in mesh_area structure. + * @param qstate: used to find mesh state. + */ +void mesh_detach_subs(struct module_qstate* qstate); + +/** + * Attach subquery. + * Creates it if it does not exist already. + * Keeps sub and super references correct. + * Performs a cycle detection - for double check - and fails if there is one. + * Also fails if the sub-sub-references become too large. + * Updates stat items in mesh_area structure. + * Pass if it is priming query or not. + * return: + * 	o if error (malloc) happened. + * 	o need to initialise the new state (module init; it is a new state). + * 	  so that the next run of the query with this module is successful. + * 	o no init needed, attachment successful. + * + * @param qstate: the state to find mesh state, and that wants to receive + * 	the results from the new subquery. + * @param qinfo: what to query for (copied). + * @param qflags: what flags to use (RD / CD flag or not). + * @param prime: if it is a (stub) priming query. + * @param valrec: if it is a validation recursion query (lookup of key, DS). + * @param newq: If the new subquery needs initialisation, it is returned, + * 	otherwise NULL is returned. + * @return: false on error, true if success (and init may be needed). + */ +int mesh_attach_sub(struct module_qstate* qstate, struct query_info* qinfo, +	uint16_t qflags, int prime, int valrec, struct module_qstate** newq); + +/** + * Add detached query. + * Creates it if it does not exist already. + * Does not make super/sub references. + * Performs a cycle detection - for double check - and fails if there is one. + * Updates stat items in mesh_area structure. + * Pass if it is priming query or not. + * return: + * 	o if error (malloc) happened. + * 	o need to initialise the new state (module init; it is a new state). + * 	  so that the next run of the query with this module is successful. + * 	o no init needed, attachment successful. + * 	o added subquery, created if it did not exist already. + * + * @param qstate: the state to find mesh state, and that wants to receive + * 	the results from the new subquery. + * @param qinfo: what to query for (copied). + * @param qflags: what flags to use (RD / CD flag or not). + * @param prime: if it is a (stub) priming query. + * @param valrec: if it is a validation recursion query (lookup of key, DS). + * @param newq: If the new subquery needs initialisation, it is returned, + * 	otherwise NULL is returned. + * @param sub: The added mesh state, created if it did not exist already. + * @return: false on error, true if success (and init may be needed). + */ +int mesh_add_sub(struct module_qstate* qstate, struct query_info* qinfo, +        uint16_t qflags, int prime, int valrec, struct module_qstate** newq, +	struct mesh_state** sub); + +/** + * Query state is done, send messages to reply entries. + * Encode messages using reply entry values and the querystate (with original + * qinfo), using given reply_info. + * Pass errcode != 0 if an error reply is needed. + * If no reply entries, nothing is done. + * Must be called before a module can module_finished or return module_error. + * The module must handle the super query states itself as well. + * + * @param mstate: mesh state that is done. return_rcode and return_msg + * 	are used for replies. + * 	return_rcode: if not 0 (NOERROR) an error is sent back (and  + * 		return_msg is ignored). + * 	return_msg: reply to encode and send back to clients. + */ +void mesh_query_done(struct mesh_state* mstate); + +/** + * Call inform_super for the super query states that are interested in the  + * results from this query state. These can then be changed for error  + * or results. + * Called when a module is module_finished or returns module_error. + * The super query states become runnable with event module_event_pass, + * it calls the current module for the super with the inform_super event. + * + * @param mesh: mesh area to add newly runnable modules to. + * @param mstate: the state that has results, used to find mesh state. + */ +void mesh_walk_supers(struct mesh_area* mesh, struct mesh_state* mstate); + +/** + * Delete mesh state, cleanup and also rbtrees and so on. + * Will detach from all super/subnodes. + * @param qstate: to remove. + */ +void mesh_state_delete(struct module_qstate* qstate); + +/* ------------------- Functions for mesh -------------------- */ + +/** + * Create and initialize a new mesh state and its query state + * Does not put the mesh state into rbtrees and so on. + * @param env: module environment to set. + * @param qinfo: query info that the mesh is for. + * @param cinfo: control info for the query client (can be NULL). + * @param qflags: flags for query (RD / CD flag). + * @param prime: if true, it is a priming query, set is_priming on mesh state. + * @param valrec: if true, it is a validation recursion query, and sets + * 	is_valrec on the mesh state. + * @return: new mesh state or NULL on allocation error. + */ +struct mesh_state* mesh_state_create(struct module_env* env, +	struct query_info* qinfo, struct respip_client_info* cinfo, +	uint16_t qflags, int prime, int valrec); + +/** + * Make a mesh state unique. + * A unique mesh state uses it's unique member to point to itself. + * @param mstate: mesh state to check. + */ +void mesh_state_make_unique(struct mesh_state* mstate); + +/** + * Cleanup a mesh state and its query state. Does not do rbtree or  + * reference cleanup. + * @param mstate: mesh state to cleanup. Its pointer may no longer be used + * 	afterwards. Cleanup rbtrees before calling this function. + */ +void mesh_state_cleanup(struct mesh_state* mstate); + +/** + * Delete all mesh states from the mesh. + * @param mesh: the mesh area to clear + */ +void mesh_delete_all(struct mesh_area* mesh); + +/** + * Find a mesh state in the mesh area. Pass relevant flags. + * + * @param mesh: the mesh area to look in. + * @param cinfo: if non-NULL client specific info that may affect IP-based + * 	actions that apply to the query result. + * @param qinfo: what query + * @param qflags: if RD / CD bit is set or not. + * @param prime: if it is a priming query. + * @param valrec: if it is a validation-recursion query. + * @return: mesh state or NULL if not found. + */ +struct mesh_state* mesh_area_find(struct mesh_area* mesh, +	struct respip_client_info* cinfo, struct query_info* qinfo, +	uint16_t qflags, int prime, int valrec); + +/** + * Setup attachment super/sub relation between super and sub mesh state. + * The relation must not be present when calling the function. + * Does not update stat items in mesh_area. + * @param super: super state. + * @param sub: sub state. + * @return: 0 on alloc error. + */ +int mesh_state_attachment(struct mesh_state* super, struct mesh_state* sub); + +/** + * Create new reply structure and attach it to a mesh state. + * Does not update stat items in mesh area. + * @param s: the mesh state. + * @param edns: edns data for reply (bufsize). + * @param rep: comm point reply info. + * @param qid: ID of reply. + * @param qflags: original query flags. + * @param qinfo: original query info. + * @return: 0 on alloc error. + */ +int mesh_state_add_reply(struct mesh_state* s, struct edns_data* edns, +	struct comm_reply* rep, uint16_t qid, uint16_t qflags, +	const struct query_info* qinfo); + +/** + * Create new callback structure and attach it to a mesh state. + * Does not update stat items in mesh area. + * @param s: the mesh state. + * @param edns: edns data for reply (bufsize). + * @param buf: buffer for reply + * @param cb: callback to call with results. + * @param cb_arg: callback user arg. + * @param qid: ID of reply. + * @param qflags: original query flags. + * @return: 0 on alloc error. + */ +int mesh_state_add_cb(struct mesh_state* s, struct edns_data* edns, +        struct sldns_buffer* buf, mesh_cb_func_type cb, void* cb_arg, +	uint16_t qid, uint16_t qflags); + +/** + * Run the mesh. Run all runnable mesh states. Which can create new + * runnable mesh states. Until completion. Automatically called by + * mesh_report_reply and mesh_new_client as needed. + * @param mesh: mesh area. + * @param mstate: first mesh state to run. + * @param ev: event the mstate. Others get event_pass. + * @param e: if a reply, its outbound entry. + */ +void mesh_run(struct mesh_area* mesh, struct mesh_state* mstate,  +	enum module_ev ev, struct outbound_entry* e); + +/** + * Print some stats about the mesh to the log. + * @param mesh: the mesh to print it for. + * @param str: descriptive string to go with it. + */ +void mesh_stats(struct mesh_area* mesh, const char* str); + +/** + * Clear the stats that the mesh keeps (number of queries serviced) + * @param mesh: the mesh + */ +void mesh_stats_clear(struct mesh_area* mesh); + +/** + * Print all the states in the mesh to the log. + * @param mesh: the mesh to print all states of. + */ +void mesh_log_list(struct mesh_area* mesh); + +/** + * Calculate memory size in use by mesh and all queries inside it. + * @param mesh: the mesh to examine. + * @return size in bytes. + */ +size_t mesh_get_mem(struct mesh_area* mesh); + +/** + * Find cycle; see if the given mesh is in the targets sub, or sub-sub, ... + * trees. + * If the sub-sub structure is too large, it returns 'a cycle'=2. + * @param qstate: given mesh querystate. + * @param qinfo: query info for dependency. + * @param flags: query flags of dependency. + * @param prime: if dependency is a priming query or not. + * @param valrec: if it is a validation recursion query (lookup of key, DS). + * @return true if the name,type,class exists and the given qstate mesh exists + * 	as a dependency of that name. Thus if qstate becomes dependent on + * 	name,type,class then a cycle is created, this is return value 1. + * 	Too large to search is value 2 (also true). + */ +int mesh_detect_cycle(struct module_qstate* qstate, struct query_info* qinfo, +	uint16_t flags, int prime, int valrec); + +/** compare two mesh_states */ +int mesh_state_compare(const void* ap, const void* bp); + +/** compare two mesh references */ +int mesh_state_ref_compare(const void* ap, const void* bp); + +/** + * Make space for another recursion state for a reply in the mesh + * @param mesh: mesh area + * @param qbuf: query buffer to save if recursion is invoked to make space. + *    This buffer is necessary, because the following sequence in calls + *    can result in an overwrite of the incoming query: + *    delete_other_mesh_query - iter_clean - serviced_delete - waiting + *    udp query is sent - on error callback - callback sends SERVFAIL reply + *    over the same network channel, and shared UDP buffer is overwritten. + *    You can pass NULL if there is no buffer that must be backed up. + * @return false if no space is available. + */ +int mesh_make_new_space(struct mesh_area* mesh, struct sldns_buffer* qbuf); + +/** + * Insert mesh state into a double linked list.  Inserted at end. + * @param m: mesh state. + * @param fp: pointer to the first-elem-pointer of the list. + * @param lp: pointer to the last-elem-pointer of the list. + */ +void mesh_list_insert(struct mesh_state* m, struct mesh_state** fp, +	struct mesh_state** lp); + +/** + * Remove mesh state from a double linked list.  Remove from any position. + * @param m: mesh state. + * @param fp: pointer to the first-elem-pointer of the list. + * @param lp: pointer to the last-elem-pointer of the list. + */ +void mesh_list_remove(struct mesh_state* m, struct mesh_state** fp, +	struct mesh_state** lp); + +/** + * Remove mesh reply entry from the reply entry list.  Searches for + * the comm_point pointer. + * @param mesh: to update the counters. + * @param m: the mesh state. + * @param cp: the comm_point to remove from the list. + */ +void mesh_state_remove_reply(struct mesh_area* mesh, struct mesh_state* m, +	struct comm_point* cp); + +/** Callback for when the serve expired client timer has run out.  Tries to + * find an expired answer in the cache and reply that to the client. + * @param arg: the argument passed to the callback. + */ +void mesh_serve_expired_callback(void* arg); + +/** + * Try to get a (expired) cached answer. + * This needs to behave like the worker's answer_from_cache() in order to have + * the same behavior as when replying from cache. + * @param qstate: the module qstate. + * @param lookup_qinfo: the query info to look for in the cache. + * @param is_expired: set if the cached answer is expired. + * @return dns_msg if a cached answer was found, otherwise NULL. + */ +struct dns_msg* +mesh_serve_expired_lookup(struct module_qstate* qstate, +	struct query_info* lookup_qinfo, int* is_expired); + +/** + * See if the mesh has space for more queries. You can allocate queries + * anyway, but this checks for the allocated space. + * @param mesh: mesh area. + * @return true if the query list is full. + * 	It checks the number of all queries, not just number of reply states, + * 	that have a client address. So that spawned queries count too, + * 	that were created by the iterator, or other modules. + */ +int mesh_jostle_exceeded(struct mesh_area* mesh); + +/** + * Give the serve expired responses. + * @param mstate: mesh state for query that has serve_expired_data. + */ +void mesh_respond_serve_expired(struct mesh_state* mstate); + +/** + * Remove callback from mesh. Removes the callback from the state. + * The state itself is left to run. Searches for the pointer values. + * + * @param mesh: the mesh. + * @param qinfo: query from client. + * @param qflags: flags from client query. + * @param cb: callback function. + * @param cb_arg: callback user arg. + */ +void mesh_remove_callback(struct mesh_area* mesh, struct query_info* qinfo, +	uint16_t qflags, mesh_cb_func_type cb, void* cb_arg); + +#endif /* SERVICES_MESH_H */  | 
