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Improve response caching logic.

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First try at handling type 3 negative replies.
This commit is contained in:
Bob Halley
1999-11-03 03:19:17 +00:00
parent 19c5c23ef6
commit 77b9650eb1
1 changed files with 73 additions and 44 deletions
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117
lib/dns/resolver.c
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@@ -151,6 +151,8 @@ struct fetchctx {
#define FCTX_ATTR_GLUING 0x02
#define FCTX_ATTR_ADDRWAIT 0x04
#define FCTX_ATTR_SHUTTINGDOWN 0x08
#define FCTX_ATTR_WANTCACHE 0x10
#define FCTX_ATTR_WANTNCACHE 0x20
#define HAVE_ANSWER(f) (((f)->attributes & FCTX_ATTR_HAVEANSWER) != \
0)
@@ -160,6 +162,8 @@ struct fetchctx {
0)
#define SHUTTINGDOWN(f) (((f)->attributes & FCTX_ATTR_SHUTTINGDOWN) \
!= 0)
#define WANTCACHE(f) (((f)->attributes & FCTX_ATTR_WANTCACHE) != 0)
#define WANTNCACHE(f) (((f)->attributes & FCTX_ATTR_WANTNCACHE) != 0)
struct dns_fetch {
unsigned int magic;
@@ -1398,6 +1402,10 @@ cache_message(fetchctx_t *fctx, isc_stdtime_t now) {
dns_section_t section;
dns_name_t *name;
FCTXTRACE("cache_message");
fctx->attributes &= ~FCTX_ATTR_WANTCACHE;
LOCK(&fctx->res->buckets[fctx->bucketnum].lock);
for (section = DNS_SECTION_ANSWER;
@@ -1440,6 +1448,10 @@ ncache_message(fetchctx_t *fctx, dns_rdatatype_t covers, isc_stdtime_t now) {
dns_fetchevent_t *event;
void *data;
FCTXTRACE("ncache_message");
fctx->attributes &= ~FCTX_ATTR_WANTNCACHE;
res = fctx->res;
need_validation = ISC_FALSE;
eresult = ISC_R_SUCCESS;
@@ -1503,6 +1515,7 @@ ncache_message(fetchctx_t *fctx, dns_rdatatype_t covers, isc_stdtime_t now) {
eresult = DNS_R_NCACHENXDOMAIN;
else
eresult = DNS_R_NCACHENXRRSET;
result = ISC_R_SUCCESS;
} else {
/*
* Either we don't care about the nature of the
@@ -1691,10 +1704,12 @@ noanswer_response(fetchctx_t *fctx, dns_name_t *oqname) {
isc_result_t result;
dns_message_t *message;
dns_name_t *name, *qname, *ns_name, *soa_name;
dns_rdataset_t *rdataset;
dns_rdataset_t *rdataset, *ns_rdataset;
isc_boolean_t done, aa, negative_response;
dns_rdatatype_t type;
FCTXTRACE("noanswer_response");
message = fctx->rmessage;
/*
@@ -1721,14 +1736,25 @@ noanswer_response(fetchctx_t *fctx, dns_name_t *oqname) {
/*
* We have to figure out if this is a negative response, or a
* referral. We start by examining the rcode.
* referral.
*/
/*
* Sometimes we can tell if its a negative response by looking at
* the message header.
*/
negative_response = ISC_FALSE;
if (message->rcode == dns_rcode_nxdomain)
if (message->rcode == dns_rcode_nxdomain ||
(message->counts[DNS_SECTION_ANSWER] == 0 &&
message->counts[DNS_SECTION_AUTHORITY] == 0))
negative_response = ISC_TRUE;
/*
* Process the authority section.
*/
done = ISC_FALSE;
ns_name = NULL;
ns_rdataset = NULL;
soa_name = NULL;
result = dns_message_firstname(message, DNS_SECTION_AUTHORITY);
while (!done && result == ISC_R_SUCCESS) {
@@ -1755,18 +1781,7 @@ noanswer_response(fetchctx_t *fctx, dns_name_t *oqname) {
rdataset->attributes |=
DNS_RDATASETATTR_CACHE;
rdataset->trust = dns_trust_glue;
/*
* Mark any additional data related
* to this rdataset.
*/
fctx->attributes |=
FCTX_ATTR_GLUING;
(void)dns_rdataset_additionaldata(
rdataset,
check_related,
fctx);
fctx->attributes &=
~FCTX_ATTR_GLUING;
ns_rdataset = rdataset;
} else if (rdataset->type ==
dns_rdatatype_soa ||
rdataset->type ==
@@ -1837,25 +1852,21 @@ noanswer_response(fetchctx_t *fctx, dns_name_t *oqname) {
ns_name->attributes &= ~DNS_NAMEATTR_CACHE;
}
/*
* A negative response without an SOA isn't useful.
*/
if (negative_response && soa_name == NULL) {
if (oqname != NULL) {
/*
* But again, we don't care if we've got an answer
* already.
*/
return (ISC_R_SUCCESS);
} else
return (DNS_R_FORMERR);
}
/*
* Do we have a referral? (We only want to follow a referral if
* we're not following a chain.)
*/
if (!negative_response && ns_name != NULL && oqname == NULL) {
/*
* Mark any additional data related to this rdataset.
* It's important that we do this before we change the
* query domain.
*/
INSIST(ns_rdataset != NULL);
fctx->attributes |= FCTX_ATTR_GLUING;
(void)dns_rdataset_additionaldata(ns_rdataset, check_related,
fctx);
fctx->attributes &= ~FCTX_ATTR_GLUING;
/*
* Set the current query domain to the referral name.
*/
@@ -1866,9 +1877,13 @@ noanswer_response(fetchctx_t *fctx, dns_name_t *oqname) {
result = dns_name_dup(ns_name, fctx->res->mctx, &fctx->domain);
if (result != ISC_R_SUCCESS)
return (result);
fctx->attributes |= FCTX_ATTR_WANTCACHE;
return (DNS_R_DELEGATION);
}
if (negative_response)
fctx->attributes |= FCTX_ATTR_WANTNCACHE;
return (ISC_R_SUCCESS);
}
@@ -1884,6 +1899,8 @@ answer_response(fetchctx_t *fctx) {
dns_rdatatype_t type;
dns_fixedname_t dname;
FCTXTRACE("answer_response");
message = fctx->rmessage;
/*
@@ -2136,6 +2153,11 @@ answer_response(fetchctx_t *fctx) {
if (!have_answer)
return (DNS_R_FORMERR);
/*
* This response is now potentially cacheable.
*/
fctx->attributes |= FCTX_ATTR_WANTCACHE;
/*
* Did chaining end before we got the final answer?
*/
@@ -2338,20 +2360,8 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
*/
get_nameservers = ISC_TRUE;
keep_trying = ISC_TRUE;
} else if (result == ISC_R_SUCCESS) {
if (message->rcode == dns_rcode_nxdomain)
covers = dns_rdatatype_any;
else
covers = fctx->type;
/*
* Cache any negative cache entries in the message.
* This may also cause work to be queued to the
* DNSSEC validator.
*/
result = ncache_message(fctx, covers, now);
if (result != ISC_R_SUCCESS)
goto done;
} else {
result = ISC_R_SUCCESS;
} else if (result != ISC_R_SUCCESS) {
/*
* Something has gone wrong.
*/
@@ -2378,7 +2388,26 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
* Cache the cacheable parts of the message. This may also cause
* work to be queued to the DNSSEC validator.
*/
result = cache_message(fctx, now);
if (WANTCACHE(fctx)) {
result = cache_message(fctx, now);
if (result != ISC_R_SUCCESS)
goto done;
}
/*
* Ncache the negatively cacheable parts of the message. This may
* also cause work to be queued to the DNSSEC validator.
*/
if (WANTNCACHE(fctx)) {
if (message->rcode == dns_rcode_nxdomain)
covers = dns_rdatatype_any;
else
covers = fctx->type;
/*
* Cache any negative cache entries in the message.
*/
result = ncache_message(fctx, covers, now);
}
done:
/*