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HADOOP-18087 support both CNAME and DNAME chaining 

- There is no way to figure out the type of alias from dnsjava's lookup. As a workaround, query CNAME first and then DNAME.
- dnsjava use "dnsjava.lookup.max_iterations" property in order to limit follow chaining. Default 16. Therefore, I think "iterations" var. in remoteLookup() is not necessary.
This commit is contained in:
이유비 2022-02-28 15:20:27 +09:00
parent dad60e77f1
commit cf1e3776b2
1 changed files with 30 additions and 39 deletions
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69
hadoop-common-project/hadoop-registry/src/main/java/org/apache/hadoop/registry/server/dns/RegistryDNS.java
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@ -1100,7 +1100,7 @@ public class RegistryDNS extends AbstractService implements DNSOperations,
LOG.debug("calling addAnswer");
byte rcode = addAnswer(response, name, type, dclass, 0, flags);
if (rcode != Rcode.NOERROR) {
rcode = remoteLookup(response, name, type, 0);
rcode = remoteLookup(response, name, type);
response.getHeader().setRcode(rcode);
}
addAdditional(response, flags);
@ -1118,55 +1118,44 @@ public class RegistryDNS extends AbstractService implements DNSOperations,
/**
* Lookup record from upstream DNS servers.
*/
private byte remoteLookup(Message response, Name name, int type,
int iterations) {
private byte remoteLookup(Message response, Name name, int type) {
// If retrieving the root zone, query for NS record type
if (name.toString().equals(".")) {
type = Type.NS;
}
// Support for CNAME chaining
if (type != Type.CNAME) {
Name targetName = name;
while (iterations < 6) {
Record[] cnameAnswers = getRecords(targetName, Type.CNAME).answers;
if (cnameAnswers == null) {
break;
}
for (Record cnameR : cnameAnswers) {
if (!response.findRecord(cnameR)) {
response.addRecord(cnameR, Section.ANSWER);
targetName = ((CNAMERecord) cnameR).getTarget();
}
}
iterations++;
}
if (iterations < 6 && !targetName.equals(name)) {
return remoteLookup(response, targetName, type, iterations + 1);
}
}
// Forward lookup to primary DNS servers
RemoteAnswer ra = getRecords(name, type);
// Support for CNAME/DNAME chaining
if (ra.aliases != null) {
for (Name targetName : ra.aliases) {
Record[] answers = getRecords(targetName, Type.CNAME).answers;
if (answers == null) {
answers = getRecords(targetName, Type.DNAME).answers;
}
if (answers != null) {
for (Record r : answers) {
if (!response.findRecord(r)) {
response.addRecord(r, Section.ANSWER);
}
}
}
}
}
Record[] answers = ra.answers;
// no answer
if (answers == null) {
return (byte)ra.rcode;
}
try {
for (Record r : answers) {
if (!response.findRecord(r)) {
if (r.getType() == Type.SOA) {
response.addRecord(r, Section.AUTHORITY);
} else {
response.addRecord(r, Section.ANSWER);
}
for (Record r : answers) {
if (!response.findRecord(r)) {
if (r.getType() == Type.SOA) {
response.addRecord(r, Section.AUTHORITY);
} else {
response.addRecord(r, Section.ANSWER);
}
}
} catch (NullPointerException e) {
return Rcode.NXDOMAIN;
} catch (Throwable e) {
return Rcode.SERVFAIL;
}
return Rcode.NOERROR;
}
@ -1196,12 +1185,12 @@ public class RegistryDNS extends AbstractService implements DNSOperations,
LOG.warn("Unexpected result from lookup: {} type: {} error: {}", name, Type.string(type), lookup.getErrorString());
break;
}
return new RemoteAnswer(lookup.getAnswers(), rcode);
return new RemoteAnswer(lookup.getAnswers(), lookup.getAliases(), rcode);
} catch (InterruptedException | ExecutionException |
TimeoutException | NullPointerException |
ExceptionInInitializerError e) {
LOG.warn("Failed to lookup: {} type: {}", name, Type.string(type), e);
return new RemoteAnswer(null, Rcode.NXDOMAIN);
return new RemoteAnswer(null, null, Rcode.NXDOMAIN);
} finally {
executor.shutdown();
}
@ -1801,10 +1790,12 @@ public class RegistryDNS extends AbstractService implements DNSOperations,
public static class RemoteAnswer {
public Record[] answers;
public Name[] aliases;
public int rcode;
public RemoteAnswer(Record[] answers, int rcode) {
public RemoteAnswer(Record[] answers, Name[] aliases, int rcode) {
this.answers = answers;
this.aliases = aliases;
this.rcode = rcode;
}
}