/*
* iterator/iter_utils.h - iterative resolver module utility functions.
*
* 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 the iterator module.
* Configuration options. Forward zones.
*/
#ifndef ITERATOR_ITER_UTILS_H
#define ITERATOR_ITER_UTILS_H
#include "iterator/iter_resptype.h"
struct sldns_buffer;
struct iter_env;
struct iter_hints;
struct iter_forwards;
struct config_file;
struct module_env;
struct delegpt_addr;
struct delegpt;
struct regional;
struct msg_parse;
struct ub_randstate;
struct query_info;
struct reply_info;
struct module_qstate;
struct sock_list;
struct ub_packed_rrset_key;
/**
* Process config options and set iterator module state.
* Sets default values if no config is found.
* @param iter_env: iterator module state.
* @param cfg: config options.
* @return 0 on error.
*/
int iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg);
/**
* Select a valid, nice target to send query to.
* Sorting and removing unsuitable targets is combined.
*
* @param iter_env: iterator module global state, with ip6 enabled and
* do-not-query-addresses.
* @param env: environment with infra cache (lameness, rtt info).
* @param dp: delegation point with result list.
* @param name: zone name (for lameness check).
* @param namelen: length of name.
* @param qtype: query type that we want to send.
* @param dnssec_lame: set to 1, if a known dnssec-lame server is selected
* these are not preferred, but are used as a last resort.
* @param chase_to_rd: set to 1 if a known recursion lame server is selected
* these are not preferred, but are used as a last resort.
* @param open_target: number of currently outstanding target queries.
* If we wait for these, perhaps more server addresses become available.
* @param blacklist: the IP blacklist to use.
* @return best target or NULL if no target.
* if not null, that target is removed from the result list in the dp.
*/
struct delegpt_addr* iter_server_selection(struct iter_env* iter_env,
struct module_env* env, struct delegpt* dp, uint8_t* name,
size_t namelen, uint16_t qtype, int* dnssec_lame,
int* chase_to_rd, int open_target, struct sock_list* blacklist);
/**
* Allocate dns_msg from parsed msg, in regional.
* @param pkt: packet.
* @param msg: parsed message (cleaned and ready for regional allocation).
* @param regional: regional to use for allocation.
* @return newly allocated dns_msg, or NULL on memory error.
*/
struct dns_msg* dns_alloc_msg(struct sldns_buffer* pkt, struct msg_parse* msg,
struct regional* regional);
/**
* Copy a dns_msg to this regional.
* @param from: dns message, also in regional.
* @param regional: regional to use for allocation.
* @return newly allocated dns_msg, or NULL on memory error.
*/
struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional);
/**
* Allocate a dns_msg with malloc/alloc structure and store in dns cache.
* @param env: environment, with alloc structure and dns cache.
* @param qinf: query info, the query for which answer is stored.
* @param rep: reply in dns_msg from dns_alloc_msg for example.
* @param is_referral: If true, then the given message to be stored is a
* referral. The cache implementation may use this as a hint.
* @param leeway: prefetch TTL leeway to expire old rrsets quicker.
* @param pside: true if dp is parentside, thus message is 'fresh' and NS
* can be prefetch-updates.
* @param region: to copy modified (cache is better) rrs back to.
* @param flags: with BIT_CD for dns64 AAAA translated queries.
* @return void, because we are not interested in alloc errors,
* the iterator and validator can operate on the results in their
* scratch space (the qstate.region) and are not dependent on the cache.
* It is useful to log the alloc failure (for the server operator),
* but the query resolution can continue without cache storage.
*/
void iter_dns_store(struct module_env* env, struct query_info* qinf,
struct reply_info* rep, int is_referral, time_t leeway, int pside,
struct regional* region, uint16_t flags);
/**
* Select randomly with n/m probability.
* For shuffle NS records for address fetching.
* @param rnd: random table
* @param n: probability.
* @param m: divisor for probability.
* @return true with n/m probability.
*/
int iter_ns_probability(struct ub_randstate* rnd, int n, int m);
/**
* Mark targets that result in a dependency cycle as done, so they
* will not get selected as targets.
* @param qstate: query state.
* @param dp: delegpt to mark ns in.
*/
void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp);
/**
* Mark targets that result in a dependency cycle as done, so they
* will not get selected as targets. For the parent-side lookups.
* @param qstate: query state.
* @param dp: delegpt to mark ns in.
*/
void iter_mark_pside_cycle_targets(struct module_qstate* qstate,
struct delegpt* dp);
/**
* See if delegation is useful or offers immediately no targets for
* further recursion.
* @param qinfo: query name and type
* @param qflags: query flags with RD flag
* @param dp: delegpt to check.
* @return true if dp is useless.
*/
int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags,
struct delegpt* dp);
/**
* See if delegation is expected to have DNSSEC information (RRSIGs) in
* its answers, or not. Inspects delegation point (name), trust anchors,
* and delegation message (DS RRset) to determine this.
* @param env: module env with trust anchors.
* @param dp: delegation point.
* @param msg: delegation message, with DS if a secure referral.
* @param dclass: class of query.
* @return 1 if dnssec is expected, 0 if not.
*/
int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp,
struct dns_msg* msg, uint16_t dclass);
/**
* See if a message contains DNSSEC.
* This is examined by looking for RRSIGs. With DNSSEC a valid answer,
* nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth
* sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records.
* @param msg: message to examine.
* @return true if DNSSEC information was found.
*/
int iter_msg_has_dnssec(struct dns_msg* msg);
/**
* See if a message is known to be from a certain zone.
* This looks for SOA or NS rrsets, for answers.
* For referrals, when one label is delegated, the zone is detected.
* Does not look at signatures.
* @param msg: the message to inspect.
* @param dp: delegation point with zone name to look for.
* @param type: type of message.
* @param dclass: class of query.
* @return true if message is certain to be from zone in dp->name.
* false if not sure (empty msg), or not from the zone.
*/
int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp,
enum response_type type, uint16_t dclass);
/**
* Check if two replies are equal
* For fallback procedures
* @param p: reply one. The reply has rrset data pointers in region.
* Does not check rrset-IDs
* @param q: reply two
* @param region: scratch buffer.
* @return if one and two are equal.
*/
int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region);
/**
* Remove unused bits from the reply if possible.
* So that caps-for-id (0x20) fallback is more likely to be successful.
* This removes like, the additional section, and NS record in the authority
* section if those records are gratuitous (not for a referral).
* @param rep: the reply to strip stuff out of.
*/
void caps_strip_reply(struct reply_info* rep);
/**
* see if reply has a 'useful' rcode for capsforid comparison, so
* not SERVFAIL or REFUSED, and thus NOERROR or NXDOMAIN.
* @param rep: reply to check.
* @return true if the rcode is a bad type of message.
*/
int caps_failed_rcode(struct reply_info* rep);
/**
* Store parent-side rrset in seperate rrset cache entries for later
* last-resort * lookups in case the child-side versions of this information
* fails.
* @param env: environment with cache, time, ...
* @param rrset: the rrset to store (copied).
* Failure to store is logged, but otherwise ignored.
*/
void iter_store_parentside_rrset(struct module_env* env,
struct ub_packed_rrset_key* rrset);
/**
* Store parent-side NS records from a referral message
* @param env: environment with cache, time, ...
* @param rep: response with NS rrset.
* Failure to store is logged, but otherwise ignored.
*/
void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep);
/**
* Store parent-side negative element, the parentside rrset does not exist,
* creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag.
* @param env: environment with cache, time, ...
* @param qinfo: the identity of the rrset that is missing.
* @param rep: delegation response or answer response, to glean TTL from.
* (malloc) failure is logged but otherwise ignored.
*/
void iter_store_parentside_neg(struct module_env* env,
struct query_info* qinfo, struct reply_info* rep);
/**
* Add parent NS record if that exists in the cache. This is both new
* information and acts like a timeout throttle on retries.
* @param env: query env with rrset cache and time.
* @param dp: delegation point to store result in. Also this dp is used to
* see which NS name is needed.
* @param region: region to alloc result in.
* @param qinfo: pertinent information, the qclass.
* @return false on malloc failure.
* if true, the routine worked and if such cached information
* existed dp->has_parent_side_NS is set true.
*/
int iter_lookup_parent_NS_from_cache(struct module_env* env,
struct delegpt* dp, struct regional* region, struct query_info* qinfo);
/**
* Add parent-side glue if that exists in the cache. This is both new
* information and acts like a timeout throttle on retries to fetch them.
* @param env: query env with rrset cache and time.
* @param dp: delegation point to store result in. Also this dp is used to
* see which NS name is needed.
* @param region: region to alloc result in.
* @param qinfo: pertinent information, the qclass.
* @return: true, it worked, no malloc failures, and new addresses (lame)
* have been added, giving extra options as query targets.
*/
int iter_lookup_parent_glue_from_cache(struct module_env* env,
struct delegpt* dp, struct regional* region, struct query_info* qinfo);
/**
* Lookup next root-hint or root-forward entry.
* @param hints: the hints.
* @param fwd: the forwards.
* @param c: the class to start searching at. 0 means find first one.
* @return false if no classes found, true if found and returned in c.
*/
int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd,
uint16_t* c);
/**
* Remove DS records that are inappropriate before they are cached.
* @param msg: the response to scrub.
* @param ns: RRSET that is the NS record for the referral.
* if NULL, then all DS records are removed from the authority section.
* @param z: zone name that the response is from.
*/
void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns,
uint8_t* z);
/**
* Remove query attempts from all available ips. For 0x20.
* @param dp: delegpt.
* @param d: decrease.
*/
void iter_dec_attempts(struct delegpt* dp, int d);
/**
* Add retry counts from older delegpt to newer delegpt.
* Does not waste time on timeout'd (or other failing) addresses.
* @param dp: new delegationpoint.
* @param old: old delegationpoint.
*/
void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old);
/**
* See if a DS response (type ANSWER) is too low: a nodata answer with
* a SOA record in the authority section at-or-below the qchase.qname.
* Also returns true if we are not sure (i.e. empty message, CNAME nosig).
* @param msg: the response.
* @param dp: the dp name is used to check if the RRSIG gives a clue that
* it was originated from the correct nameserver.
* @return true if too low.
*/
int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp);
/**
* See if delegpt can go down a step to the qname or not
* @param qinfo: the query name looked up.
* @param dp: checked if the name can go lower to the qname
* @return true if can go down, false if that would not be possible.
* the current response seems to be the one and only, best possible, response.
*/
int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp);
#endif /* ITERATOR_ITER_UTILS_H */
