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Leniency for target discovery when under load (for NRDelegation changes) (#764)

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* - Introduce leniency for target discovery when under load.

* - Allow for easier testing (to be reverted).

* - Happy compiler.

* - Precheck access to target_fetch_policy.

* - Do not mark a nameserver as resolved when one of A/AAAA is negative.

* - Update fetch_glue.rpl test for (possible) outstanding queries.

* - Update fetch_glue_cname.rpl test for possible outstanding queries.

* - Better fix for fetch_glue_cname.rpl.

* - Fix iter_emptydp_for_glue.rpl to match the referral.

* - Disabled the nxns tests for now (to be reverted).

* - Update iter_recurse.rpl for possible outstanding queries.

* Revert "- Disabled the nxns tests for now (to be reverted)."

This reverts commit 34a9c13a90.

* Revert "- Allow for easier testing (to be reverted)."

This reverts commit b6dfe35e1d.
This commit is contained in:
Yorgos Thessalonikefs 2022-10-04 22:21:08 +02:00 committed by GitHub
parent f0614a57f8
commit f1d263a318
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6 changed files with 54 additions and 86 deletions
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55
iterator/iterator.c
View File

@ -255,9 +255,9 @@ error_supers(struct module_qstate* qstate, int id, struct module_qstate* super)
log_err("out of memory adding missing");
}
delegpt_mark_neg(dpns, qstate->qinfo.qtype);
dpns->resolved = 1; /* mark as failed */
if((dpns->got4 == 2 || !ie->supports_ipv4) &&
(dpns->got6 == 2 || !ie->supports_ipv6)) {
dpns->resolved = 1; /* mark as failed */
target_count_increase_nx(super_iq, 1);
}
}
@ -2264,6 +2264,7 @@ processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
size_t qout_orig_len = 0;
int sq_check_ratelimit = 1;
int sq_was_ratelimited = 0;
int can_do_promisc = 0;
/* NOTE: a request will encounter this state for each target it
* needs to send a query to. That is, at least one per referral,
@ -2591,12 +2592,12 @@ processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
if(iq->depth < ie->max_dependency_depth
&& iq->num_target_queries == 0
&& (!iq->target_count || iq->target_count[TARGET_COUNT_NX]==0)
&& iq->sent_count < TARGET_FETCH_STOP
/* if the mesh query list is full, then do not waste cpu
* and sockets to fetch promiscuous targets. They can be
* looked up when needed. */
&& !mesh_jostle_exceeded(qstate->env->mesh)
) {
&& iq->sent_count < TARGET_FETCH_STOP) {
can_do_promisc = 1;
}
/* if the mesh query list is full, then do not waste cpu and sockets to
* fetch promiscuous targets. They can be looked up when needed. */
if(can_do_promisc && !mesh_jostle_exceeded(qstate->env->mesh)) {
tf_policy = ie->target_fetch_policy[iq->depth];
}
@ -2768,6 +2769,37 @@ processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
return 0;
}
/* We have a target. We could have created promiscuous target
* queries but we are currently under pressure (mesh_jostle_exceeded).
* If we are configured to allow promiscuous target queries and haven't
* gone out to the network for a target query for this delegation, then
* it is possible to slip in a promiscuous one with a 1/10 chance. */
if(can_do_promisc && tf_policy == 0 && iq->depth == 0
&& iq->depth < ie->max_dependency_depth
&& ie->target_fetch_policy[iq->depth] != 0
&& iq->dp_target_count == 0
&& !ub_random_max(qstate->env->rnd, 10)) {
int extra = 0;
verbose(VERB_ALGO, "available target exists in cache but "
"attempt to get extra 1 target");
(void)query_for_targets(qstate, iq, ie, id, 1, &extra);
/* errors ignored, these targets are not strictly necessary for
* this result, we do not have to reply with SERVFAIL */
if(extra > 0) {
iq->num_target_queries += extra;
target_count_increase(iq, extra);
check_waiting_queries(iq, qstate, id);
/* undo qname minimise step because we'll get back here
* to do it again */
if(qout_orig && iq->minimise_count > 0) {
iq->minimise_count--;
iq->qinfo_out.qname = qout_orig;
iq->qinfo_out.qname_len = qout_orig_len;
}
return 0;
}
}
/* Do not check ratelimit for forwarding queries or if we already got a
* pass. */
sq_check_ratelimit = (!(iq->chase_flags & BIT_RD) && !iq->ratelimit_ok);
@ -3531,12 +3563,13 @@ processTargetResponse(struct module_qstate* qstate, int id,
} else {
verbose(VERB_ALGO, "iterator TargetResponse failed");
delegpt_mark_neg(dpns, qstate->qinfo.qtype);
dpns->resolved = 1; /* fail the target */
if((dpns->got4 == 2 || !ie->supports_ipv4) &&
(dpns->got6 == 2 || !ie->supports_ipv6) &&
(dpns->got6 == 2 || !ie->supports_ipv6)) {
dpns->resolved = 1; /* fail the target */
/* do not count cached answers */
(qstate->reply_origin && qstate->reply_origin->len != 0)) {
target_count_increase_nx(foriq, 1);
if(qstate->reply_origin && qstate->reply_origin->len != 0) {
target_count_increase_nx(foriq, 1);
}
}
}
}

2
iterator/iterator.h
View File

@ -324,7 +324,7 @@ struct iter_qstate {
/** the number of times this query has been restarted. */
int query_restart_count;
/** the number of times this query as followed a referral. */
/** the number of times this query has followed a referral. */
int referral_count;
/** number of queries fired off */

33
testdata/fetch_glue.rpl vendored
View File

@ -176,36 +176,7 @@ SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ENTRY_END
; due to ordering of answer packets, this is still outstanding, remove it
STEP 21 CHECK_OUT_QUERY
ENTRY_BEGIN
ADJUST copy_id
MATCH qname qtype
REPLY QR
SECTION QUESTION
ns.example.com IN AAAA
ENTRY_END
; some more recursion needed.
; to finish the NS query
STEP 40 QUERY
ENTRY_BEGIN
REPLY RD
SECTION QUESTION
. IN NS
ENTRY_END
STEP 41 CHECK_ANSWER
ENTRY_BEGIN
MATCH all
REPLY QR RD RA NOERROR
SECTION QUESTION
. IN NS
SECTION ANSWER
. IN NS K.ROOT-SERVERS.NET.
SECTION AUTHORITY
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
; let (possible) outstanding queries finish resolving
STEP 21 TRAFFIC
SCENARIO_END

35
testdata/fetch_glue_cname.rpl vendored
View File

@ -155,7 +155,7 @@ ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
REPLY QR AA NOERROR
SECTION QUESTION
ns.example.com. IN AAAA
SECTION AUTHORITY
@ -188,36 +188,7 @@ SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ENTRY_END
; due to ordering of answer packets, this is still outstanding, remove it
STEP 21 CHECK_OUT_QUERY
ENTRY_BEGIN
ADJUST copy_id
MATCH qname qtype
REPLY QR
SECTION QUESTION
ns.example.com IN AAAA
ENTRY_END
; some more recursion needed.
; to finish the NS query
STEP 40 QUERY
ENTRY_BEGIN
REPLY RD
SECTION QUESTION
. IN NS
ENTRY_END
STEP 41 CHECK_ANSWER
ENTRY_BEGIN
MATCH all
REPLY QR RD RA NOERROR
SECTION QUESTION
. IN NS
SECTION ANSWER
. IN NS K.ROOT-SERVERS.NET.
SECTION AUTHORITY
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
; let (possible) outstanding queries finish resolving
STEP 21 TRAFFIC
SCENARIO_END

4
testdata/iter_emptydp_for_glue.rpl vendored
View File

@ -164,11 +164,11 @@ a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
ENTRY_BEGIN
MATCH opcode qname
MATCH opcode subdomain
ADJUST copy_id copy_query
REPLY QR NOERROR
SECTION QUESTION
ns.example.org. IN A
example.org. IN A
SECTION AUTHORITY
example.org. NS ns.example.net.
example.org. NS ns.example.org.

11
testdata/iter_recurse.rpl vendored
View File

@ -216,14 +216,7 @@ example.com. IN NS ns.example.net.
;ns.example.net IN A 1.2.3.44
ENTRY_END
; due to ordering of answer packets, this is still outstanding, remove it
STEP 21 CHECK_OUT_QUERY
ENTRY_BEGIN
ADJUST copy_id
MATCH qname qtype
REPLY QR
SECTION QUESTION
ns.example.net IN AAAA
ENTRY_END
; let (possible) outstanding queries finish resolving
STEP 21 TRAFFIC
SCENARIO_END