iter_utils.h File Reference

This file contains functions to assist the iterator module. More...

#include "iterator/iter_resptype.h"

Functions
int	iter_apply_cfg (struct iter_env *iter_env, struct config_file *cfg)
	Process config options and set iterator module state.
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_expected, int *chase_to_rd, int open_target, struct sock_list *blacklist)
	Select a valid, nice target to send query to.
struct dns_msg *	dns_alloc_msg (ldns_buffer *pkt, struct msg_parse *msg, struct regional *regional)
	Allocate dns_msg from parsed msg, in regional.
struct dns_msg *	dns_copy_msg (struct dns_msg *from, struct regional *regional)
	Copy a dns_msg to this regional.
int	iter_dns_store (struct module_env *env, struct query_info *qinf, struct reply_info *rep, int is_referral, uint32_t leeway)
	Allocate a dns_msg with malloc/alloc structure and store in dns cache.
int	iter_ns_probability (struct ub_randstate *rnd, int n, int m)
	Select randomly with n/m probability.
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.
int	iter_suspect_exists (struct query_info *qinfo, struct delegpt *dp, struct module_env *env)
	See if query is in-zone glue and we suspect that it exists.
int	iter_dp_is_useless (struct query_info *qinfo, uint16_t qflags, struct delegpt *dp)
	See if delegation is useful or offers immediately no targets for further recursion.
int	iter_indicates_dnssec (struct module_env *env, struct delegpt *dp, struct dns_msg *msg, uint16_t dclass)
	See if delegation is expected to have DNSSEC information (RRSIGs) in its answers, or not.
int	iter_msg_has_dnssec (struct dns_msg *msg)
	See if a message contains DNSSEC.
int	iter_msg_from_zone (struct dns_msg *msg, struct delegpt *dp, enum response_type type, uint16_t dclass)
	See if a message is known to be from a certain zone.
int	reply_equal (struct reply_info *p, struct reply_info *q)
	Check if two replies are equal For fallback procedures.
void	iter_store_inzone_glue (struct module_env *env, struct query_info *qinfo, struct reply_info *rep)
	Store in-zone glue in seperate rrset cache entries for later last-resort lookups in case the child-side versions of this information fails.
int	iter_lookup_inzone_glue (struct module_env *env, struct delegpt *dp, struct regional *region, struct query_info *qinfo)
	Find in-zone glue from rrset cache again.
int	iter_get_next_root (struct iter_hints *hints, struct iter_forwards *fwd, uint16_t *c)
	Lookup next root-hint or root-forward entry.
void	iter_scrub_ds (struct dns_msg *msg, struct ub_packed_rrset_key *ns, uint8_t *z)
	Remove DS records that are inappropriate before they are cached.

---

Detailed Description

This file contains functions to assist the iterator module.

Configuration options. Forward zones.

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Function Documentation

int iter_apply_cfg	(	struct iter_env *	iter_env,
		struct config_file *	cfg
	)

Process config options and set iterator module state.

Sets default values if no config is found.

Parameters:

	iter_env,:	iterator module state.
	cfg,:	config options.

Returns:

0 on error.

References config_file::do_ip6, iter_env::donotq, donotq_apply_cfg(), donotq_create(), iter_env::hints, hints_apply_cfg(), hints_create(), log_err(), iter_env::max_dependency_depth, iter_env::priv, priv_apply_cfg(), priv_create(), read_fetch_policy(), iter_env::supports_ipv6, iter_env::target_fetch_policy, config_file::target_fetch_policy, VERB_QUERY, and verbose().

Referenced by iter_init().

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_expected,
		int *	chase_to_rd,
		int	open_target,
		struct sock_list *	blacklist
	)			[read]

Select a valid, nice target to send query to.

Sorting and removing unsuitable targets is combined.

Parameters:

	iter_env,:	iterator module global state, with ip6 enabled and do-not-query-addresses.
	env,:	environment with infra cache (lameness, rtt info).
	dp,:	delegation point with result list.
	name,:	zone name (for lameness check).
	namelen,:	length of name.
	qtype,:	query type that we want to send.
	dnssec_expected,:	set to 0, if a known dnssec-lame server is selected these are not preferred, but are used as a last resort.
	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.
	open_target,:	number of currently outstanding target queries. If we wait for these, perhaps more server addresses become available.
	blacklist,:	the IP blacklist to use.

Returns:

best target or NULL if no target. if not null, that target is removed from the result list in the dp.

References delegpt_addr::attempts, BLACKLIST_PENALTY, iter_filter_order(), log_assert, delegpt_addr::next_result, module_env::now, OUTBOUND_MSG_RETRY, delegpt::result_list, module_env::rnd, ub_random(), USEFUL_SERVER_TOP_TIMEOUT, VERB_ALGO, and verbose().

Referenced by processQueryTargets().

struct dns_msg* dns_alloc_msg	(	ldns_buffer *	pkt,
		struct msg_parse *	msg,
		struct regional *	regional
	)			[read]

Allocate dns_msg from parsed msg, in regional.

Parameters:

	pkt,:	packet.
	msg,:	parsed message (cleaned and ready for regional allocation).
	regional,:	regional to use for allocation.

Returns:

newly allocated dns_msg, or NULL on memory error.

References log_err(), parse_create_msg(), dns_msg::qinfo, regional_alloc(), and dns_msg::rep.

Referenced by process_response().

struct dns_msg* dns_copy_msg	(	struct dns_msg *	from,
		struct regional *	regional
	)			[read]

Copy a dns_msg to this regional.

Parameters:

	from,:	dns message, also in regional.
	regional,:	regional to use for allocation.

Returns:

newly allocated dns_msg, or NULL on memory error.

References dns_msg::qinfo, query_info::qname, query_info::qname_len, regional_alloc(), regional_alloc_init(), dns_msg::rep, and reply_info_copy().

Referenced by prime_supers(), and processClassResponse().

int iter_dns_store	(	struct module_env *	env,
		struct query_info *	qinf,
		struct reply_info *	rep,
		int	is_referral,
		uint32_t	leeway
	)

Allocate a dns_msg with malloc/alloc structure and store in dns cache.

Parameters:

	env,:	environment, with alloc structure and dns cache.
	qinf,:	query info, the query for which answer is stored.
	rep,:	reply in dns_msg from dns_alloc_msg for example.
	is_referral,:	If true, then the given message to be stored is a referral. The cache implementation may use this as a hint.
	leeway,:	prefetch TTL leeway to expire old rrsets quicker.

Returns:

0 on alloc error (out of memory).

References dns_cache_store().

Referenced by error_response_cache(), processFinished(), and processQueryResponse().

int iter_ns_probability	(	struct ub_randstate *	rnd,
		int	n,
		int	m
	)

Select randomly with n/m probability.

For shuffle NS records for address fetching.

Parameters:

	rnd,:	random table
	n,:	probability.
	m,:	divisor for probability.

Returns:

true with n/m probability.

References ub_random().

Referenced by query_for_targets().

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.

Parameters:

	qstate,:	query state.
	dp,:	delegpt to mark ns in.

References causes_cycle(), log_nametypeclass(), delegpt_ns::name, delegpt_ns::namelen, delegpt_ns::next, delegpt::nslist, query_info::qclass, module_qstate::qinfo, delegpt_ns::resolved, and VERB_QUERY.

Referenced by query_for_targets().

int iter_suspect_exists	(	struct query_info *	qinfo,
		struct delegpt *	dp,
		struct module_env *	env
	)

See if query is in-zone glue and we suspect that it exists.

Suspicion that it exists, is if there is no A or AAAA in cache (since one of them is expected for an NS record) or the qtype is in cache but was recently expired (so we have seen this data recently).

Parameters:

	qinfo,:	query info.
	dp,:	delegation point we are at.
	env,:	environment with rrset cache.

Returns:

true if suspect that this glue exists.

References lruhash_entry::data, delegpt_find_ns(), dname_subdomain_c(), ub_packed_rrset_key::entry, lruhash_entry::lock, delegpt::name, module_env::now, query_info::qclass, query_info::qname, query_info::qname_len, query_info::qtype, module_env::rrset_cache, rrset_cache_lookup(), SUSPICION_RECENT_EXPIRY, packed_rrset_data::ttl, VERB_ALGO, and verbose().

Referenced by processQueryTargets().

int iter_dp_is_useless	(	struct query_info *	qinfo,
		uint16_t	qflags,
		struct delegpt *	dp
	)

See if delegation is useful or offers immediately no targets for further recursion.

Parameters:

	qinfo,:	query name and type
	qflags,:	query flags with RD flag
	dp,:	delegpt to check.

References BIT_RD, delegpt_find_ns(), dname_subdomain_c(), delegpt_ns::name, delegpt::name, delegpt_ns::next, delegpt::nslist, query_info::qname, query_info::qname_len, query_info::qtype, delegpt_ns::resolved, delegpt::result_list, and delegpt::usable_list.

Referenced by print_deleg_lookup(), and processInitRequest().

int iter_indicates_dnssec	(	struct module_env *	env,
		struct delegpt *	dp,
		struct dns_msg *	msg,
		uint16_t	dclass
	)

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.

Parameters:

	env,:	module env with trust anchors.
	dp,:	delegation point.
	msg,:	delegation message, with DS if a secure referral.
	dclass,:	class of query.

Returns:

1 if dnssec is expected, 0 if not.

References anchor_find(), module_env::anchors, trust_anchor::lock, delegpt::name, delegpt::namelabs, delegpt::namelen, dns_msg::rep, and reply_find_rrset_section_ns().

Referenced by generate_target_query(), prime_root(), prime_stub(), processInitRequest3(), and processQueryResponse().

int iter_msg_has_dnssec

(

struct dns_msg *

msg

)

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.

Parameters:

msg,:

message to examine.

Returns:

true if DNSSEC information was found.

References reply_info::an_numrrsets, reply_info::ns_numrrsets, dns_msg::rep, and reply_info::rrsets.

Referenced by processQueryResponse().

int iter_msg_from_zone	(	struct dns_msg *	msg,
		struct delegpt *	dp,
		enum response_type	type,
		uint16_t	dclass
	)

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.

Parameters:

	msg,:	the message to inspect.
	dp,:	delegation point with zone name to look for.
	type,:	type of message.
	dclass,:	class of query.

Returns:

true if message is certain to be from zone in dp->name. false if not sure (empty msg), or not from the zone.

References reply_info::an_numrrsets, packed_rrset_key::dname, dname_count_labels(), dname_strict_subdomain(), log_assert, delegpt::name, delegpt::namelabs, delegpt::namelen, reply_info::ns_numrrsets, dns_msg::rep, reply_find_rrset_section_an(), reply_find_rrset_section_ns(), RESPONSE_TYPE_ANSWER, RESPONSE_TYPE_CNAME, RESPONSE_TYPE_REFERRAL, ub_packed_rrset_key::rk, packed_rrset_key::rrset_class, reply_info::rrsets, and packed_rrset_key::type.

Referenced by processQueryResponse().

int reply_equal	(	struct reply_info *	p,
		struct reply_info *	q
	)

Check if two replies are equal For fallback procedures.

Parameters:

	p,:	reply one. The reply has rrset data pointers in region. Does not check rrset-IDs
	q,:	reply two

Returns:

if one and two are equal.

References reply_info::an_numrrsets, reply_info::ar_numrrsets, reply_info::flags, reply_info::ns_numrrsets, reply_info::prefetch_ttl, reply_info::qdcount, reply_info::rrset_count, rrset_equal(), reply_info::rrsets, reply_info::security, and reply_info::ttl.

Referenced by process_response().

void iter_store_inzone_glue	(	struct module_env *	env,
		struct query_info *	qinfo,
		struct reply_info *	rep
	)

Store in-zone glue in seperate rrset cache entries for later last-resort lookups in case the child-side versions of this information fails.

Parameters:

	env,:	environment with cache, time, ...
	qinfo,:	query info. must match the information stored to avoid Kaminsky-style trouble.
	rep,:	reply with possibly A or AAAA content to store.

References module_env::alloc, ub_packed_rrset_key::entry, packed_rrset_key::flags, lruhash_entry::hash, ub_packed_rrset_key::id, rrset_ref::id, rrset_ref::key, log_err(), module_env::now, packed_rrset_copy_alloc(), PACKED_RRSET_PARENT_SIDE, query_info::qclass, query_info::qname, query_info::qname_len, query_info::qtype, reply_find_rrset(), ub_packed_rrset_key::rk, module_env::rrset_cache, rrset_cache_update(), and rrset_key_hash().

Referenced by processQueryResponse().

int iter_lookup_inzone_glue	(	struct module_env *	env,
		struct delegpt *	dp,
		struct regional *	region,
		struct query_info *	qinfo
	)

Find in-zone glue from rrset cache again.

Parameters:

	env,:	query env with rrset cache and time.
	dp,:	delegation point to store result in.
	region,:	region to alloc result in.
	qinfo,:	query into that is pertinent.

Returns:

false on malloc failure.

References delegpt_add_rrset_A(), delegpt_add_rrset_AAAA(), ub_packed_rrset_key::entry, lruhash_entry::lock, module_env::now, PACKED_RRSET_PARENT_SIDE, query_info::qclass, query_info::qname, query_info::qname_len, query_info::qtype, module_env::rrset_cache, and rrset_cache_lookup().

Referenced by processTargetResponse().

int iter_get_next_root	(	struct iter_hints *	hints,
		struct iter_forwards *	fwd,
		uint16_t *	c
	)

Lookup next root-hint or root-forward entry.

Parameters:

	hints,:	the hints.
	fwd,:	the forwards.
	c,:	the class to start searching at. 0 means find first one.

Returns:

false if no classes found, true if found and returned in c.

References forwards_next_root(), and hints_next_root().

Referenced by processCollectClass().

void iter_scrub_ds	(	struct dns_msg *	msg,
		struct ub_packed_rrset_key *	ns,
		uint8_t *	z
	)

Remove DS records that are inappropriate before they are cached.

Parameters:

	msg,:	the response to scrub.
	ns,:	RRSET that is the NS record for the referral. if NULL, then all DS records are removed from the authority section.
	z,:	zone name that the response is from.

References reply_info::an_numrrsets, packed_rrset_key::dname, dname_subdomain_c(), log_nametypeclass(), reply_info::ns_numrrsets, query_dname_compare(), dns_msg::rep, ub_packed_rrset_key::rk, packed_rrset_key::rrset_class, reply_info::rrset_count, reply_info::rrsets, packed_rrset_key::type, and VERB_ALGO.

Referenced by processQueryResponse().