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Remove child delegations from cache when grandchild delegations are returned from parent #1053

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Apr 23, 2024
+395 −46
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Remove child delegations from cache when grandchild delegations are returned from parent #1053

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18 changes: 18 additions & 0 deletions iterator/iterator.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@
#include "iterator/iter_priv.h"
#include "validator/val_neg.h"
#include "services/cache/dns.h"
#include "services/cache/rrset.h"
#include "services/cache/infra.h"
#include "services/authzone.h"
#include "util/module.h"
Expand Down Expand Up @@ -3255,6 +3256,7 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
}
return final_state(iq);
} else if(type == RESPONSE_TYPE_REFERRAL) {
struct delegpt* old_dp = NULL;
/* REFERRAL type responses get a reset of the
* delegation point, and back to the QUERYTARGETS_STATE. */
verbose(VERB_DETAIL, "query response was REFERRAL");
Expand Down Expand Up @@ -3306,13 +3308,29 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
/* Reset the event state, setting the current delegation
* point to the referral. */
iq->deleg_msg = iq->response;
/* Keep current delegation point for label comparison */
old_dp = iq->dp;
iq->dp = delegpt_from_message(iq->response, qstate->region);
if (qstate->env->cfg->qname_minimisation)
iq->minimisation_state = INIT_MINIMISE_STATE;
if(!iq->dp) {
errinf(qstate, "malloc failure, for delegation point");
return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
}
if(old_dp->namelabs + 1 < iq->dp->namelabs) {
/* We got a grandchild delegation (more than one label
* difference) than expected. Check for in-between
* delegations in the cache and remove them.
* They could prove problematic when they expire
* and rrset_expired_above() encounters them during
* delegation cache lookups. */
uint8_t* qname = iq->dp->name;
size_t qnamelen = iq->dp->namelen;
rrset_cache_remove_above(qstate->env->rrset_cache,
&qname, &qnamelen, LDNS_RR_TYPE_NS,
iq->qchase.qclass, *qstate->env->now,
old_dp->name, old_dp->namelen);
}
if(!cache_fill_missing(qstate->env, iq->qchase.qclass,
qstate->region, iq->dp)) {
errinf(qstate, "malloc failure, copy extra info into delegation point");
Expand Down
52 changes: 6 additions & 46 deletions services/cache/dns.c
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Original file line number Diff line number Diff line change
Expand Up @@ -193,46 +193,6 @@ dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
slabhash_insert(env->msg_cache, hash, &e->entry, rep, env->alloc);
}

/** see if an rrset is expired above the qname, return upper qname. */
static int
rrset_expired_above(struct module_env* env, uint8_t** qname, size_t* qnamelen,
uint16_t searchtype, uint16_t qclass, time_t now, uint8_t* expiretop,
size_t expiretoplen)
{
struct ub_packed_rrset_key *rrset;
uint8_t lablen;

while(*qnamelen > 0) {
/* look one label higher */
lablen = **qname;
*qname += lablen + 1;
*qnamelen -= lablen + 1;
if(*qnamelen <= 0)
break;

/* looks up with a time of 0, to see expired entries */
if((rrset = rrset_cache_lookup(env->rrset_cache, *qname,
*qnamelen, searchtype, qclass, 0, 0, 0))) {
struct packed_rrset_data* data =
(struct packed_rrset_data*)rrset->entry.data;
if(now > data->ttl) {
/* it is expired, this is not wanted */
lock_rw_unlock(&rrset->entry.lock);
log_nametypeclass(VERB_ALGO, "this rrset is expired", *qname, searchtype, qclass);
return 1;
}
/* it is not expired, continue looking */
lock_rw_unlock(&rrset->entry.lock);
}

/* do not look above the expiretop. */
if(expiretop && *qnamelen == expiretoplen &&
query_dname_compare(*qname, expiretop)==0)
break;
}
return 0;
}

/** find closest NS or DNAME and returns the rrset (locked) */
static struct ub_packed_rrset_key*
find_closest_of_type(struct module_env* env, uint8_t* qname, size_t qnamelen,
Expand Down Expand Up @@ -266,12 +226,12 @@ find_closest_of_type(struct module_env* env, uint8_t* qname, size_t qnamelen,
/* check for expiry, but we have to let go of the rrset
* for the lock ordering */
lock_rw_unlock(&rrset->entry.lock);
/* the expired_above function always takes off one
* label (if qnamelen>0) and returns the final qname
* where it searched, so we can continue from there
* turning the O N*N search into O N. */
if(!rrset_expired_above(env, &qname, &qnamelen,
searchtype, qclass, now, expiretop,
/* the rrset_cache_expired_above function always takes
* off one label (if qnamelen>0) and returns the final
* qname where it searched, so we can continue from
* there turning the O N*N search into O N. */
if(!rrset_cache_expired_above(env->rrset_cache, &qname,
&qnamelen, searchtype, qclass, now, expiretop,
expiretoplen)) {
/* we want to return rrset, but it may be
* gone from cache, if so, just loop like
Expand Down
84 changes: 84 additions & 0 deletions services/cache/rrset.c
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@
#include "util/data/packed_rrset.h"
#include "util/data/msgreply.h"
#include "util/data/msgparse.h"
#include "util/data/dname.h"
#include "util/regional.h"
#include "util/alloc.h"
#include "util/net_help.h"
Expand Down Expand Up @@ -443,6 +444,89 @@ rrset_check_sec_status(struct rrset_cache* r,
lock_rw_unlock(&e->lock);
}

void
rrset_cache_remove_above(struct rrset_cache* r, uint8_t** qname, size_t*
qnamelen, uint16_t searchtype, uint16_t qclass, time_t now, uint8_t*
qnametop, size_t qnametoplen)
{
struct ub_packed_rrset_key *rrset;
uint8_t lablen;

while(*qnamelen > 0) {
/* look one label higher */
lablen = **qname;
*qname += lablen + 1;
*qnamelen -= lablen + 1;
if(*qnamelen <= 0)
return;

/* stop at qnametop */
if(qnametop && *qnamelen == qnametoplen &&
query_dname_compare(*qname, qnametop)==0)
return;

if(verbosity >= VERB_ALGO) {
/* looks up with a time of 0, to see expired entries */
if((rrset = rrset_cache_lookup(r, *qname,
*qnamelen, searchtype, qclass, 0, 0, 0))) {
struct packed_rrset_data* data =
(struct packed_rrset_data*)rrset->entry.data;
int expired = (now > data->ttl);
lock_rw_unlock(&rrset->entry.lock);
if(expired)
log_nametypeclass(verbosity, "this "
"(grand)parent rrset will be "
"removed (expired)",
*qname, searchtype, qclass);
else log_nametypeclass(verbosity, "this "
"(grand)parent rrset will be "
"removed",
*qname, searchtype, qclass);
}
}
rrset_cache_remove(r, *qname, *qnamelen, searchtype, qclass, 0);
}
}

int
rrset_cache_expired_above(struct rrset_cache* r, uint8_t** qname, size_t*
qnamelen, uint16_t searchtype, uint16_t qclass, time_t now, uint8_t*
qnametop, size_t qnametoplen)
{
struct ub_packed_rrset_key *rrset;
uint8_t lablen;

while(*qnamelen > 0) {
/* look one label higher */
lablen = **qname;
*qname += lablen + 1;
*qnamelen -= lablen + 1;
if(*qnamelen <= 0)
break;

/* looks up with a time of 0, to see expired entries */
if((rrset = rrset_cache_lookup(r, *qname,
*qnamelen, searchtype, qclass, 0, 0, 0))) {
struct packed_rrset_data* data =
(struct packed_rrset_data*)rrset->entry.data;
if(now > data->ttl) {
/* it is expired, this is not wanted */
lock_rw_unlock(&rrset->entry.lock);
log_nametypeclass(VERB_ALGO, "this rrset is expired", *qname, searchtype, qclass);
return 1;
}
/* it is not expired, continue looking */
lock_rw_unlock(&rrset->entry.lock);
}

/* do not look above the qnametop. */
if(qnametop && *qnamelen == qnametoplen &&
query_dname_compare(*qname, qnametop)==0)
break;
}
return 0;
}

void rrset_cache_remove(struct rrset_cache* r, uint8_t* nm, size_t nmlen,
uint16_t type, uint16_t dclass, uint32_t flags)
{
Expand Down
31 changes: 31 additions & 0 deletions services/cache/rrset.h
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Original file line number Diff line number Diff line change
Expand Up @@ -231,6 +231,37 @@ void rrset_update_sec_status(struct rrset_cache* r,
void rrset_check_sec_status(struct rrset_cache* r,
struct ub_packed_rrset_key* rrset, time_t now);

/**
* Removes rrsets above the qname, returns upper qname.
* @param r: the rrset cache.
* @param qname: the start qname, also used as the output.
* @param qnamelen: length of qname, updated when it returns.
* @param searchtype: qtype to search for.
* @param qclass: qclass to search for.
* @param now: current time.
* @param qnametop: the top qname to stop removal (it is not removed).
* @param qnametoplen: length of qnametop.
*/
void rrset_cache_remove_above(struct rrset_cache* r, uint8_t** qname,
size_t* qnamelen, uint16_t searchtype, uint16_t qclass, time_t now,
uint8_t* qnametop, size_t qnametoplen);

/**
* Sees if an rrset is expired above the qname, returns upper qname.
* @param r: the rrset cache.
* @param qname: the start qname, also used as the output.
* @param qnamelen: length of qname, updated when it returns.
* @param searchtype: qtype to search for.
* @param qclass: qclass to search for.
* @param now: current time.
* @param qnametop: the top qname, don't look farther than that.
* @param qnametoplen: length of qnametop.
* @return true if there is an expired rrset above, false otherwise.
*/
int rrset_cache_expired_above(struct rrset_cache* r, uint8_t** qname,
size_t* qnamelen, uint16_t searchtype, uint16_t qclass, time_t now,
uint8_t* qnametop, size_t qnametoplen);

/**
* Remove an rrset from the cache, by name and type and flags
* @param r: rrset cache
Expand Down
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