Motivation:
DnsResolver.resolve(...) fails when an InetSocketAddress is used that was constructed of an ipaddress string.
Modifications:
Don't try to lookup when the InetSocketAddress was constructed via an ipaddress.
Result:
DnsResolver.resolve(...) works in all cases.
Related: #3797
Motivation:
There is a race condition where DnsNameResolver.query() can attempt to
increase the reference count of the DNS response which was released
already by other thread.
Modifications:
- Make DnsCacheEntry a top-level class for clear access control
- Use 'synchronized' to avoid the race condition
- Add DnsCacheEntry.retainedResponse() to make sure that the response
is never released while it is retained
- Make retainedResponse() return null when the response has been
released already, so that DnsNameResolver.query() knows that the
cached entry has been released
Result:
The forementioned race condition has been fixed.
Motivation:
There are various known issues in netty-codec-dns:
- Message types are not interfaces, which can make it difficult for a
user to implement his/her own message implementation.
- Some class names and field names do not match with the terms in the
RFC.
- The support for decoding a DNS record was limited. A user had to
encode and decode by him/herself.
- The separation of DnsHeader from DnsMessage was unnecessary, although
it is fine conceptually.
- Buffer leak caused by DnsMessage was difficult to analyze, because the
leak detector tracks down the underlying ByteBuf rather than the
DnsMessage itself.
- DnsMessage assumes DNS-over-UDP.
- To send an EDNS message, a user have to create a new DNS record class
instance unnecessarily.
Modifications:
- Make all message types interfaces and add default implementations
- Rename some classes, properties, and constants to match the RFCs
- DnsResource -> DnsRecord
- DnsType -> DnsRecordType
- and many more
- Remove DnsClass and use an integer to support EDNS better
- Add DnsRecordEncoder/DnsRecordDecoder and their default
implementations
- DnsRecord does not require RDATA to be ByteBuf anymore.
- Add DnsRawRecord as the catch-all record type
- Merge DnsHeader into DnsMessage
- Make ResourceLeakDetector track AbstractDnsMessage
- Remove DnsMessage.sender/recipient properties
- Wrap DnsMessage with AddressedEnvelope
- Add DatagramDnsQuest and DatagramDnsResponse for ease of use
- Rename DnsQueryEncoder to DatagramDnsQueryEncoder
- Rename DnsResponseDecoder to DatagramDnsResponseDecoder
- Miscellaneous changes
- Add StringUtil.TAB
Result:
- Cleaner APi
- Can support DNS-over-TCP more easily in the future
- Reduced memory footprint in the default DnsQuery/Response
implementations
- Better leak tracking for DnsMessages
- Possibility to introduce new DnsRecord types in the future and provide
full record encoder/decoder implementation.
- No unnecessary instantiation for an EDNS pseudo resource record
Related: #3173
Motivation:
DnsNameResolver was using InetSocketAddress.getHostString() which is
only available since Java 7.
Modifications:
Use InetSocketAddress.getHostName() in lieu of getHostString() when the
current Java version is less than 7.
Result:
DnsNameResolver runs fine on Java 6.
Related: #3149
Motivation:
DnsQueryContext, using the DatagramChannel bound in DnsNameResolver,
blindly writes to the channel without checking the bind future for
success.
Modifications:
Check the bindFuture before writing a DNS query to a DatagramChannel
Result:
Bug fixed
Motivation:
So far, we relied on the domain name resolution mechanism provided by
JDK. It served its purpose very well, but had the following
shortcomings:
- Domain name resolution is performed in a blocking manner.
This becomes a problem when a user has to connect to thousands of
different hosts. e.g. web crawlers
- It is impossible to employ an alternative cache/retry policy.
e.g. lower/upper bound in TTL, round-robin
- It is impossible to employ an alternative name resolution mechanism.
e.g. Zookeeper-based name resolver
Modification:
- Add the resolver API in the new module: netty-resolver
- Implement the DNS-based resolver: netty-resolver-dns
.. which uses netty-codec-dns
- Make ChannelFactory reusable because it's now used by
io.netty.bootstrap, io.netty.resolver.dns, and potentially by other
modules in the future
- Move ChannelFactory from io.netty.bootstrap to io.netty.channel
- Deprecate the old ChannelFactory
- Add ReflectiveChannelFactory
Result:
It is trivial to resolve a large number of domain names asynchronously.
