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DnsNameResovlerContext#followCname sending extra queries

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Motivation:
When following a CNAME response DnsNameResovlerContext may issue a A and AAAA query. However the DnsNameResolverContext would have already issued a A and AAAA query to get the CNAME response, and this may result in 2 additional A/AAAA queries per CNAME response.

Modifications:
- DnsNameResovlerContext#followCname shouldn't issue 2 queries, but instead just a single query with the same record type as the original query

Result:
No more duplicate queries as a result of CNAME responses.
This commit is contained in:
Scott Mitchell 2018-02-01 17:17:01 -08:00 committed by Norman Maurer
parent fbbaf2bd7e
commit 46e66b45bd
1 changed files with 11 additions and 25 deletions
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36
resolver-dns/src/main/java/io/netty/resolver/dns/DnsNameResolverContext.java
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@ -571,7 +571,7 @@ abstract class DnsNameResolverContext<T> {
}
if (found) {
followCname(resolved, queryLifecycleObserver, promise);
followCname(question, resolved, queryLifecycleObserver, promise);
} else {
queryLifecycleObserver.queryFailed(CNAME_NOT_FOUND_QUERY_FAILED_EXCEPTION);
}
@ -753,33 +753,19 @@ abstract class DnsNameResolverContext<T> {
return stream == null ? nameServerAddrs.duplicate() : stream;
}
private void followCname(String cname, final DnsQueryLifecycleObserver queryLifecycleObserver, Promise<T> promise) {
// Use the same server for both CNAME queries
private void followCname(
DnsQuestion question, String cname, DnsQueryLifecycleObserver queryLifecycleObserver, Promise<T> promise) {
DnsServerAddressStream stream = getNameServers(cname);
DnsQuestion cnameQuestion = null;
if (parent.supportsARecords()) {
try {
if ((cnameQuestion = newQuestion(cname, DnsRecordType.A)) == null) {
return;
}
} catch (Throwable cause) {
queryLifecycleObserver.queryFailed(cause);
PlatformDependent.throwException(cause);
}
query(stream, 0, cnameQuestion, queryLifecycleObserver.queryCNAMEd(cnameQuestion), promise, null);
}
if (parent.supportsAAAARecords()) {
try {
if ((cnameQuestion = newQuestion(cname, DnsRecordType.AAAA)) == null) {
return;
}
} catch (Throwable cause) {
queryLifecycleObserver.queryFailed(cause);
PlatformDependent.throwException(cause);
}
query(stream, 0, cnameQuestion, queryLifecycleObserver.queryCNAMEd(cnameQuestion), promise, null);
final DnsQuestion cnameQuestion;
try {
cnameQuestion = newQuestion(cname, question.type());
} catch (Throwable cause) {
queryLifecycleObserver.queryFailed(cause);
PlatformDependent.throwException(cause);
return;
}
query(stream, 0, cnameQuestion, queryLifecycleObserver.queryCNAMEd(cnameQuestion), promise, null);
}
private boolean query(String hostname, DnsRecordType type, DnsServerAddressStream dnsServerAddressStream,