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Diffstat (limited to 'contrib/unbound/util/module.h')
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diff --git a/contrib/unbound/util/module.h b/contrib/unbound/util/module.h new file mode 100644 index 0000000..dace1cf --- /dev/null +++ b/contrib/unbound/util/module.h @@ -0,0 +1,515 @@ +/* + * util/module.h - DNS handling module interface + * + * 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 the interface for DNS handling modules. + * + * The module interface uses the DNS modules as state machines. The + * state machines are activated in sequence to operate on queries. Once + * they are done, the reply is passed back. In the usual setup the mesh + * is the caller of the state machines and once things are done sends replies + * and invokes result callbacks. + * + * The module provides a number of functions, listed in the module_func_block. + * The module is inited and destroyed and memory usage queries, for the + * module as a whole, for entire-module state (such as a cache). And per-query + * functions are called, operate to move the state machine and cleanup of + * the per-query state. + * + * Most per-query state should simply be allocated in the query region. + * This is destroyed at the end of the query. + * + * The module environment contains services and information and caches + * shared by the modules and the rest of the system. It also contains + * function pointers for module-specific tasks (like sending queries). + * + * *** Example module calls for a normal query + * + * In this example, the query does not need recursion, all the other data + * can be found in the cache. This makes the example shorter. + * + * At the start of the program the iterator module is initialised. + * The iterator module sets up its global state, such as donotquery lists + * and private address trees. + * + * A query comes in, and a mesh entry is created for it. The mesh + * starts the resolution process. The validator module is the first + * in the list of modules, and it is started on this new query. The + * operate() function is called. The validator decides it needs not do + * anything yet until there is a result and returns wait_module, that + * causes the next module in the list to be started. + * + * The next module is the iterator. It is started on the passed query and + * decides to perform a lookup. For this simple example, the delegation + * point information is available, and all the iterator wants to do is + * send a UDP query. The iterator uses env.send_query() to send the + * query. Then the iterator suspends (returns from the operate call). + * + * When the UDP reply comes back (and on errors and timeouts), the + * operate function is called for the query, on the iterator module, + * with the event that there is a reply. The iterator decides that this + * is enough, the work is done. It returns the value finished from the + * operate call, which causes the previous module to be started. + * + * The previous module, the validator module, is started with the event + * that the iterator module is done. The validator decides to validate + * the query. Once it is done (which could take recursive lookups, but + * in this example no recursive lookups are needed), it returns from the + * operate function with finished. + * + * There is no previous module from the validator module, and the mesh + * takes this to mean that the query is finally done. The mesh invokes + * callbacks and sends packets to queriers. + * + * If other modules had been waiting (recursively) on the answer to this + * query, then the mesh will tell them about it. It calls the inform_super + * routine on all the waiting modules, and once that is done it calls all of + * them with the operate() call. During inform_super the query that is done + * still exists and information can be copied from it (but the module should + * not really re-entry codepoints and services). During the operate call + * the modules can use stored state to continue operation with the results. + * (network buffers are used to contain the answer packet during the + * inform_super phase, but after that the network buffers will be cleared + * of their contents so that other tasks can be performed). + * + * *** Example module calls for recursion + * + * A module is called in operate, and it decides that it wants to perform + * recursion. That is, it wants the full state-machine-list to operate on + * a different query. It calls env.attach_sub() to create a new query state. + * The routine returns the newly created state, and potentially the module + * can edit the module-states for the newly created query (i.e. pass along + * some information, like delegation points). The module then suspends, + * returns from the operate routine. + * + * The mesh meanwhile will have the newly created query (or queries) on + * a waiting list, and will call operate() on this query (or queries). + * It starts again at the start of the module list for them. The query + * (or queries) continue to operate their state machines, until they are + * done. When they are done the mesh calls inform_super on the module that + * wanted the recursion. After that the mesh calls operate() on the module + * that wanted to do the recursion, and during this phase the module could, + * for example, decide to create more recursions. + * + * If the module decides it no longer wants the recursive information + * it can call detach_subs. Those queries will still run to completion, + * potentially filling the cache with information. Inform_super is not + * called any more. + * + * The iterator module will fetch items from the cache, so a recursion + * attempt may complete very quickly if the item is in cache. The calling + * module has to wait for completion or eventual timeout. A recursive query + * that times out returns a servfail rcode (servfail is also returned for + * other errors during the lookup). + * + * Results are passed in the qstate, the rcode member is used to pass + * errors without requiring memory allocation, so that the code can continue + * in out-of-memory conditions. If the rcode member is 0 (NOERROR) then + * the dns_msg entry contains a filled out message. This message may + * also contain an rcode that is nonzero, but in this case additional + * information (query, additional) can be passed along. + * + * The rcode and dns_msg are used to pass the result from the the rightmost + * module towards the leftmost modules and then towards the user. + * + * If you want to avoid recursion-cycles where queries need other queries + * that need the first one, use detect_cycle() to see if that will happen. + * + */ + +#ifndef UTIL_MODULE_H +#define UTIL_MODULE_H +#include "util/storage/lruhash.h" +#include "util/data/msgreply.h" +#include "util/data/msgparse.h" +struct sldns_buffer; +struct alloc_cache; +struct rrset_cache; +struct key_cache; +struct config_file; +struct slabhash; +struct query_info; +struct edns_data; +struct regional; +struct worker; +struct module_qstate; +struct ub_randstate; +struct mesh_area; +struct mesh_state; +struct val_anchors; +struct val_neg_cache; +struct iter_forwards; +struct iter_hints; + +/** Maximum number of modules in operation */ +#define MAX_MODULE 5 + +/** + * Module environment. + * Services and data provided to the module. + */ +struct module_env { + /* --- data --- */ + /** config file with config options */ + struct config_file* cfg; + /** shared message cache */ + struct slabhash* msg_cache; + /** shared rrset cache */ + struct rrset_cache* rrset_cache; + /** shared infrastructure cache (edns, lameness) */ + struct infra_cache* infra_cache; + /** shared key cache */ + struct key_cache* key_cache; + + /* --- services --- */ + /** + * Send serviced DNS query to server. UDP/TCP and EDNS is handled. + * operate() should return with wait_reply. Later on a callback + * will cause operate() to be called with event timeout or reply. + * The time until a timeout is calculated from roundtrip timing, + * several UDP retries are attempted. + * @param qname: query name. (host order) + * @param qnamelen: length in bytes of qname, including trailing 0. + * @param qtype: query type. (host order) + * @param qclass: query class. (host order) + * @param flags: host order flags word, with opcode and CD bit. + * @param dnssec: if set, EDNS record will have bits set. + * If EDNS_DO bit is set, DO bit is set in EDNS records. + * If BIT_CD is set, CD bit is set in queries with EDNS records. + * @param want_dnssec: if set, the validator wants DNSSEC. Without + * EDNS, the answer is likely to be useless for this domain. + * @param addr: where to. + * @param addrlen: length of addr. + * @param zone: delegation point name. + * @param zonelen: length of zone name. + * @param q: wich query state to reactivate upon return. + * @return: false on failure (memory or socket related). no query was + * sent. Or returns an outbound entry with qsent and qstate set. + * This outbound_entry will be used on later module invocations + * that involve this query (timeout, error or reply). + */ + struct outbound_entry* (*send_query)(uint8_t* qname, size_t qnamelen, + uint16_t qtype, uint16_t qclass, uint16_t flags, int dnssec, + int want_dnssec, struct sockaddr_storage* addr, + socklen_t addrlen, uint8_t* zone, size_t zonelen, + struct module_qstate* q); + + /** + * 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 (*detach_subs)(struct module_qstate* qstate); + + /** + * Attach subquery. + * Creates it if it does not exist already. + * Keeps sub and super references correct. + * 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 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 (*attach_sub)(struct module_qstate* qstate, + struct query_info* qinfo, uint16_t qflags, int prime, + struct module_qstate** newq); + + /** + * Kill newly attached sub. If attach_sub returns newq for + * initialisation, but that fails, then this routine will cleanup and + * delete the fresly created sub. + * @param newq: the new subquery that is no longer needed. + * It is removed. + */ + void (*kill_sub)(struct module_qstate* newq); + + /** + * Detect if adding a dependency for qstate on name,type,class will + * create a dependency cycle. + * @param qstate: given mesh querystate. + * @param qinfo: query info for dependency. + * @param flags: query flags of dependency, RD/CD flags. + * @param prime: if dependency is a priming query or not. + * @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. + */ + int (*detect_cycle)(struct module_qstate* qstate, + struct query_info* qinfo, uint16_t flags, int prime); + + /** region for temporary usage. May be cleared after operate() call. */ + struct regional* scratch; + /** buffer for temporary usage. May be cleared after operate() call. */ + struct sldns_buffer* scratch_buffer; + /** internal data for daemon - worker thread. */ + struct worker* worker; + /** mesh area with query state dependencies */ + struct mesh_area* mesh; + /** allocation service */ + struct alloc_cache* alloc; + /** random table to generate random numbers */ + struct ub_randstate* rnd; + /** time in seconds, converted to integer */ + time_t* now; + /** time in microseconds. Relatively recent. */ + struct timeval* now_tv; + /** is validation required for messages, controls client-facing + * validation status (AD bits) and servfails */ + int need_to_validate; + /** trusted key storage; these are the configured keys, if not NULL, + * otherwise configured by validator. These are the trust anchors, + * and are not primed and ready for validation, but on the bright + * side, they are read only memory, thus no locks and fast. */ + struct val_anchors* anchors; + /** negative cache, configured by the validator. if not NULL, + * contains NSEC record lookup trees. */ + struct val_neg_cache* neg_cache; + /** the 5011-probe timer (if any) */ + struct comm_timer* probe_timer; + /** Mapping of forwarding zones to targets. + * iterator forwarder information. per-thread, created by worker */ + struct iter_forwards* fwds; + /** + * iterator forwarder information. per-thread, created by worker. + * The hints -- these aren't stored in the cache because they don't + * expire. The hints are always used to "prime" the cache. Note + * that both root hints and stub zone "hints" are stored in this + * data structure. + */ + struct iter_hints* hints; + /** module specific data. indexed by module id. */ + void* modinfo[MAX_MODULE]; +}; + +/** + * External visible states of the module state machine + * Modules may also have an internal state. + * Modules are supposed to run to completion or until blocked. + */ +enum module_ext_state { + /** initial state - new query */ + module_state_initial = 0, + /** waiting for reply to outgoing network query */ + module_wait_reply, + /** module is waiting for another module */ + module_wait_module, + /** module is waiting for another module; that other is restarted */ + module_restart_next, + /** module is waiting for sub-query */ + module_wait_subquery, + /** module could not finish the query */ + module_error, + /** module is finished with query */ + module_finished +}; + +/** + * Events that happen to modules, that start or wakeup modules. + */ +enum module_ev { + /** new query */ + module_event_new = 0, + /** query passed by other module */ + module_event_pass, + /** reply inbound from server */ + module_event_reply, + /** no reply, timeout or other error */ + module_event_noreply, + /** reply is there, but capitalisation check failed */ + module_event_capsfail, + /** next module is done, and its reply is awaiting you */ + module_event_moddone, + /** error */ + module_event_error +}; + +/** + * Linked list of sockaddrs + * May be allocated such that only 'len' bytes of addr exist for the structure. + */ +struct sock_list { + /** next in list */ + struct sock_list* next; + /** length of addr */ + socklen_t len; + /** sockaddr */ + struct sockaddr_storage addr; +}; + +/** + * Module state, per query. + */ +struct module_qstate { + /** which query is being answered: name, type, class */ + struct query_info qinfo; + /** flags uint16 from query */ + uint16_t query_flags; + /** if this is a (stub or root) priming query (with hints) */ + int is_priming; + + /** comm_reply contains server replies */ + struct comm_reply* reply; + /** the reply message, with message for client and calling module */ + struct dns_msg* return_msg; + /** the rcode, in case of error, instead of a reply message */ + int return_rcode; + /** origin of the reply (can be NULL from cache, list for cnames) */ + struct sock_list* reply_origin; + /** IP blacklist for queries */ + struct sock_list* blacklist; + /** region for this query. Cleared when query process finishes. */ + struct regional* region; + /** failure reason information if val-log-level is high */ + struct config_strlist* errinf; + + /** which module is executing */ + int curmod; + /** module states */ + enum module_ext_state ext_state[MAX_MODULE]; + /** module specific data for query. indexed by module id. */ + void* minfo[MAX_MODULE]; + /** environment for this query */ + struct module_env* env; + /** mesh related information for this query */ + struct mesh_state* mesh_info; + /** how many seconds before expiry is this prefetched (0 if not) */ + time_t prefetch_leeway; +}; + +/** + * Module functionality block + */ +struct module_func_block { + /** text string name of module */ + const char* name; + + /** + * init the module. Called once for the global state. + * This is the place to apply settings from the config file. + * @param env: module environment. + * @param id: module id number. + * return: 0 on error + */ + int (*init)(struct module_env* env, int id); + + /** + * de-init, delete, the module. Called once for the global state. + * @param env: module environment. + * @param id: module id number. + */ + void (*deinit)(struct module_env* env, int id); + + /** + * accept a new query, or work further on existing query. + * Changes the qstate->ext_state to be correct on exit. + * @param ev: event that causes the module state machine to + * (re-)activate. + * @param qstate: the query state. + * Note that this method is not allowed to change the + * query state 'identity', that is query info, qflags, + * and priming status. + * Attach a subquery to get results to a different query. + * @param id: module id number that operate() is called on. + * @param outbound: if not NULL this event is due to the reply/timeout + * or error on this outbound query. + * @return: if at exit the ext_state is: + * o wait_module: next module is started. (with pass event). + * o error or finished: previous module is resumed. + * o otherwise it waits until that event happens (assumes + * the service routine to make subrequest or send message + * have been called. + */ + void (*operate)(struct module_qstate* qstate, enum module_ev event, + int id, struct outbound_entry* outbound); + + /** + * inform super querystate about the results from this subquerystate. + * Is called when the querystate is finished. The method invoked is + * the one from the current module active in the super querystate. + * @param qstate: the query state that is finished. + * Examine return_rcode and return_reply in the qstate. + * @param id: module id for this module. + * This coincides with the current module for the super qstate. + * @param super: the super querystate that needs to be informed. + */ + void (*inform_super)(struct module_qstate* qstate, int id, + struct module_qstate* super); + + /** + * clear module specific data + */ + void (*clear)(struct module_qstate* qstate, int id); + + /** + * How much memory is the module specific data using. + * @param env: module environment. + * @param id: the module id. + * @return the number of bytes that are alloced. + */ + size_t (*get_mem)(struct module_env* env, int id); +}; + +/** + * Debug utility: module external qstate to string + * @param s: the state value. + * @return descriptive string. + */ +const char* strextstate(enum module_ext_state s); + +/** + * Debug utility: module event to string + * @param e: the module event value. + * @return descriptive string. + */ +const char* strmodulevent(enum module_ev e); + +#endif /* UTIL_MODULE_H */ |
