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Diffstat (limited to 'external/unbound/iterator/iterator.h')
| -rw-r--r-- | external/unbound/iterator/iterator.h | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/external/unbound/iterator/iterator.h b/external/unbound/iterator/iterator.h new file mode 100644 index 000000000..0b91760d4 --- /dev/null +++ b/external/unbound/iterator/iterator.h @@ -0,0 +1,372 @@ +/* + * iterator/iterator.h - iterative resolver DNS query response module + * + * 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 a module that performs recusive iterative DNS query + * processing. + */ + +#ifndef ITERATOR_ITERATOR_H +#define ITERATOR_ITERATOR_H +#include "services/outbound_list.h" +#include "util/data/msgreply.h" +#include "util/module.h" +struct delegpt; +struct iter_hints; +struct iter_forwards; +struct iter_donotq; +struct iter_prep_list; +struct iter_priv; + +/** max number of query restarts. Determines max number of CNAME chain. */ +#define MAX_RESTART_COUNT 8 +/** max number of referrals. Makes sure resolver does not run away */ +#define MAX_REFERRAL_COUNT 130 +/** max number of queries-sent-out. Make sure large NS set does not loop */ +#define MAX_SENT_COUNT 32 +/** at what query-sent-count to stop target fetch policy */ +#define TARGET_FETCH_STOP 3 +/** how nice is a server without further information, in msec + * Equals rtt initial timeout value. + */ +#define UNKNOWN_SERVER_NICENESS 376 +/** maximum timeout before a host is deemed unsuitable, in msec. + * After host_ttl this will be timed out and the host will be tried again. + * Equals RTT_MAX_TIMEOUT + */ +#define USEFUL_SERVER_TOP_TIMEOUT 120000 +/** number of retries on outgoing queries */ +#define OUTBOUND_MSG_RETRY 5 +/** RTT band, within this amount from the best, servers are chosen randomly. + * Chosen so that the UNKNOWN_SERVER_NICENESS falls within the band of a + * fast server, this causes server exploration as a side benefit. msec. */ +#define RTT_BAND 400 +/** Start value for blacklisting a host, 2*USEFUL_SERVER_TOP_TIMEOUT in sec */ +#define INFRA_BACKOFF_INITIAL 240 + +/** + * Global state for the iterator. + */ +struct iter_env { + /** A flag to indicate whether or not we have an IPv6 route */ + int supports_ipv6; + + /** A flag to indicate whether or not we have an IPv4 route */ + int supports_ipv4; + + /** A set of inetaddrs that should never be queried. */ + struct iter_donotq* donotq; + + /** private address space and private domains */ + struct iter_priv* priv; + + /** The maximum dependency depth that this resolver will pursue. */ + int max_dependency_depth; + + /** + * The target fetch policy for each dependency level. This is + * described as a simple number (per dependency level): + * negative numbers (usually just -1) mean fetch-all, + * 0 means only fetch on demand, and + * positive numbers mean to fetch at most that many targets. + * array of max_dependency_depth+1 size. + */ + int* target_fetch_policy; +}; + +/** + * State of the iterator for a query. + */ +enum iter_state { + /** + * Externally generated queries start at this state. Query restarts are + * reset to this state. + */ + INIT_REQUEST_STATE = 0, + + /** + * Root priming events reactivate here, most other events pass + * through this naturally as the 2nd part of the INIT_REQUEST_STATE. + */ + INIT_REQUEST_2_STATE, + + /** + * Stub priming events reactivate here, most other events pass + * through this naturally as the 3rd part of the INIT_REQUEST_STATE. + */ + INIT_REQUEST_3_STATE, + + /** + * Each time a delegation point changes for a given query or a + * query times out and/or wakes up, this state is (re)visited. + * This state is reponsible for iterating through a list of + * nameserver targets. + */ + QUERYTARGETS_STATE, + + /** + * Responses to queries start at this state. This state handles + * the decision tree associated with handling responses. + */ + QUERY_RESP_STATE, + + /** Responses to priming queries finish at this state. */ + PRIME_RESP_STATE, + + /** Collecting query class information, for qclass=ANY, when + * it spawns off queries for every class, it returns here. */ + COLLECT_CLASS_STATE, + + /** Find NS record to resolve DS record from, walking to the right + * NS spot until we find it */ + DSNS_FIND_STATE, + + /** Responses that are to be returned upstream end at this state. + * As well as responses to target queries. */ + FINISHED_STATE +}; + +/** + * Per query state for the iterator module. + */ +struct iter_qstate { + /** + * State of the iterator module. + * This is the state that event is in or should sent to -- all + * requests should start with the INIT_REQUEST_STATE. All + * responses should start with QUERY_RESP_STATE. Subsequent + * processing of the event will change this state. + */ + enum iter_state state; + + /** + * Final state for the iterator module. + * This is the state that responses should be routed to once the + * response is final. For externally initiated queries, this + * will be FINISHED_STATE, locally initiated queries will have + * different final states. + */ + enum iter_state final_state; + + /** + * The depth of this query, this means the depth of recursion. + * This address is needed for another query, which is an address + * needed for another query, etc. Original client query has depth 0. + */ + int depth; + + /** + * The response + */ + struct dns_msg* response; + + /** + * This is a list of RRsets that must be prepended to the + * ANSWER section of a response before being sent upstream. + */ + struct iter_prep_list* an_prepend_list; + /** Last element of the prepend list */ + struct iter_prep_list* an_prepend_last; + + /** + * This is the list of RRsets that must be prepended to the + * AUTHORITY section of the response before being sent upstream. + */ + struct iter_prep_list* ns_prepend_list; + /** Last element of the authority prepend list */ + struct iter_prep_list* ns_prepend_last; + + /** query name used for chasing the results. Initially the same as + * the state qinfo, but after CNAMEs this will be different. + * The query info used to elicit the results needed. */ + struct query_info qchase; + /** query flags to use when chasing the answer (i.e. RD flag) */ + uint16_t chase_flags; + /** true if we set RD bit because of last resort recursion lame query*/ + int chase_to_rd; + + /** + * This is the current delegation point for an in-progress query. This + * object retains state as to which delegation targets need to be + * (sub)queried for vs which ones have already been visited. + */ + struct delegpt* dp; + + /** state for 0x20 fallback when capsfail happens, 0 not a fallback */ + int caps_fallback; + /** state for capsfail: current server number to try */ + size_t caps_server; + /** state for capsfail: stored query for comparisons. Can be NULL if + * no response had been seen prior to starting the fallback. */ + struct reply_info* caps_reply; + + /** Current delegation message - returned for non-RD queries */ + struct dns_msg* deleg_msg; + + /** number of outstanding target sub queries */ + int num_target_queries; + + /** outstanding direct queries */ + int num_current_queries; + + /** the number of times this query has been restarted. */ + int query_restart_count; + + /** the number of times this query as followed a referral. */ + int referral_count; + + /** number of queries fired off */ + int sent_count; + + /** + * The query must store NS records from referrals as parentside RRs + * Enabled once it hits resolution problems, to throttle retries. + * If enabled it is the pointer to the old delegation point with + * the old retry counts for bad-nameserver-addresses. + */ + struct delegpt* store_parent_NS; + + /** + * The query is for parent-side glue(A or AAAA) for a nameserver. + * If the item is seen as glue in a referral, and pside_glue is NULL, + * then it is stored in pside_glue for later. + * If it was never seen, at the end, then a negative caching element + * must be created. + * The (data or negative) RR cache element then throttles retries. + */ + int query_for_pside_glue; + /** the parent-side-glue element (NULL if none, its first match) */ + struct ub_packed_rrset_key* pside_glue; + + /** If nonNULL we are walking upwards from DS query to find NS */ + uint8_t* dsns_point; + /** length of the dname in dsns_point */ + size_t dsns_point_len; + + /** + * expected dnssec information for this iteration step. + * If dnssec rrsigs are expected and not given, the server is marked + * lame (dnssec-lame). + */ + int dnssec_expected; + + /** + * We are expecting dnssec information, but we also know the server + * is DNSSEC lame. The response need not be marked dnssec-lame again. + */ + int dnssec_lame_query; + + /** + * This is flag that, if true, means that this event is + * waiting for a stub priming query. + */ + int wait_priming_stub; + + /** + * This is a flag that, if true, means that this query is + * for (re)fetching glue from a zone. Since the address should + * have been glue, query again to the servers that should have + * been returning it as glue. + * The delegation point must be set to the one that should *not* + * be used when creating the state. A higher one will be attempted. + */ + int refetch_glue; + + /** list of pending queries to authoritative servers. */ + struct outbound_list outlist; +}; + +/** + * List of prepend items + */ +struct iter_prep_list { + /** next in list */ + struct iter_prep_list* next; + /** rrset */ + struct ub_packed_rrset_key* rrset; +}; + +/** + * Get the iterator function block. + * @return: function block with function pointers to iterator methods. + */ +struct module_func_block* iter_get_funcblock(void); + +/** + * Get iterator state as a string + * @param state: to convert + * @return constant string that is printable. + */ +const char* iter_state_to_string(enum iter_state state); + +/** + * See if iterator state is a response state + * @param s: to inspect + * @return true if response state. + */ +int iter_state_is_responsestate(enum iter_state s); + +/** iterator init */ +int iter_init(struct module_env* env, int id); + +/** iterator deinit */ +void iter_deinit(struct module_env* env, int id); + +/** iterator operate on a query */ +void iter_operate(struct module_qstate* qstate, enum module_ev event, int id, + struct outbound_entry* outbound); + +/** + * Return priming query results to interestes super querystates. + * + * Sets the delegation point and delegation message (not nonRD queries). + * This is a callback from walk_supers. + * + * @param qstate: query state that finished. + * @param id: module id. + * @param super: the qstate to inform. + */ +void iter_inform_super(struct module_qstate* qstate, int id, + struct module_qstate* super); + +/** iterator cleanup query state */ +void iter_clear(struct module_qstate* qstate, int id); + +/** iterator alloc size routine */ +size_t iter_get_mem(struct module_env* env, int id); + +#endif /* ITERATOR_ITERATOR_H */ |