Motivation:
It is possible that the user uses a too big EDNS0 setting for the MTU and so we may receive a truncated datagram packet. In this case we should try to detect this and retry via TCP if possible
Modifications:
- Fix detecting of incomplete records
- Mark response as truncated if we did not consume the whole packet
- Add unit test
Result:
Fixes https://github.com/netty/netty/issues/9365
Motivation:
When decoding DnsRecord, if the record contains compression pointers, and not all compression pointers are decompressed, but part of the pointers are decompressed. Then when encoding the record, the compressed pointer will point to the wrong location, resulting in bad label problem.
Modification:
Pre-decompressed record RData that may contain compression pointers.
Result:
Fixes#8962
Motivation:
Sometimes DNS responses can be very large which mean they will not fit in a UDP packet. When this is happening the DNS server will set the TC flag (truncated flag) to tell the resolver that the response was truncated. When a truncated response was received we should allow to retry via TCP and use the received response (if possible) as a replacement for the truncated one.
See https://tools.ietf.org/html/rfc7766.
Modifications:
- Add support for TCP fallback by allow to specify a socketChannelFactory / socketChannelType on the DnsNameResolverBuilder. If this is set to something different then null we will try to fallback to TCP.
- Add decoder / encoder for TCP
- Add unit tests
Result:
Support for TCP fallback as defined by https://tools.ietf.org/html/rfc7766 when using DnsNameResolver.
Motivation:
We can replace some "hand-rolled" integer checks with our own static utility method to simplify the code.
Modifications:
Use methods provided by `ObjectUtil`.
Result:
Cleaner code and less duplication
Motivation:
We can just use Objects.requireNonNull(...) as a replacement for ObjectUtil.checkNotNull(....)
Modifications:
- Use Objects.requireNonNull(...)
Result:
Less code to maintain.
Motivation:
We can use the diamond operator these days.
Modification:
Use diamond operator whenever possible.
Result:
More modern code and less boiler-plate.
Motivation:
When the ECS source prefix length is not a mutiple of 8, the last byte the address inside the
ECS OPT record is not padded properly.
Modifications:
DefaultDnsRecordEncoder.padWithZeros(...) was modified to add padding from the least
significant bits.
Result:
ECS encoding bug fixed.
Motivation:
We need to ensure the tracked object can not be GC'ed before ResourceLeak.close() is called as otherwise we may get false-positives reported by the ResourceLeakDetector. This can happen as the JIT / GC may be able to figure out that we do not need the tracked object anymore and so already enqueue it for collection before we actually get a chance to close the enclosing ResourceLeak.
Modifications:
- Add ResourceLeakTracker and deprecate the old ResourceLeak
- Fix some javadocs to correctly release buffers.
- Add a unit test for ResourceLeakDetector that shows that ResourceLeakTracker has not the problems.
Result:
No more false-positives reported by ResourceLeakDetector when ResourceLeakDetector.track(...) is used.
Motivation:
8cf90f0512 switch a duplicate opreration to a slice operation. Typically this would be fine but DNS supports a compression (https://www.ietf.org/rfc/rfc1035 4.1.4. Message compression) where the payload contains absolute indexes which refer back to previously referenced content. Using a slice will break the ability for the indexes in the payload to correctly self reference to the index of the originial payload, and thus decoding may fail.
Modifications:
- Use duplicate instead of slice so DNS message compression and index references are preserved.
Result:
Fixes DefaultDnsRecordDecoder regression
Motivation:
the build doesnt seem to enforce this, so they piled up
Modifications:
removed unused import lines
Result:
less unused imports
Signed-off-by: radai-rosenblatt <radai.rosenblatt@gmail.com>
Motivation:
RFC7871 defines an extension which allows to request responses for a given subset.
Modifications:
- Add DnsOptPseudoRrRecord which can act as base class for extensions based on EDNS(0) as defined in RFC6891
- Add DnsOptEcsRecord to support the Client Subnet in DNS Queries extension
- Add tests
Result:
Client Subnet in DNS Queries extension is now supported.
Motivation:
We need to not change the original writerIndex when decode a DnsPtrRecord as otherwise we will not be able to decode other records that follow it.
Modifications:
Slice the data out and so not increase the writerIndex.
Result:
No more problems when decoding.
Allow users of Netty to plug in their own leak detector for the purpose
of instrumentation.
Motivation:
We are rolling out a large Netty deployment and want to be able to
track the amount of leaks we're seeing in production via custom
instrumentation. In order to achieve this today, I had to plug in a
custom `ByteBufAllocator` into the bootstrap and have it initialize a
custom `ResourceLeakDetector`. Due to these classes mostly being marked
`final` or having private or static methods, a lot of the code had to
be copy-pasted and it's quite ugly.
Modifications:
* I've added a static loader method for the `ResourceLeakDetector` in
`AbstractByteBuf` that tries to instantiate the class passed in via the
`-Dio.netty.customResourceLeakDetector`, otherwise falling back to the
default one.
* I've modified `ResourceLeakDetector` to be non-final and to have the
reporting broken out in to methods that can be overridden.
Result:
You can instrument leaks in your application by just adding something
like the following:
```java
public class InstrumentedResourceLeakDetector<T> extends
ResourceLeakDetector<T> {
@Monitor("InstanceLeakCounter")
private final AtomicInteger instancesLeakCounter;
@Monitor("LeakCounter")
private final AtomicInteger leakCounter;
public InstrumentedResourceLeakDetector(Class<T> resource) {
super(resource);
this.instancesLeakCounter = new AtomicInteger();
this.leakCounter = new AtomicInteger();
}
@Override
protected void reportTracedLeak(String records) {
super.reportTracedLeak(records);
leakCounter.incrementAndGet();
}
@Override
protected void reportUntracedLeak() {
super.reportUntracedLeak();
leakCounter.incrementAndGet();
}
@Override
protected void reportInstancesLeak() {
super.reportInstancesLeak();
instancesLeakCounter.incrementAndGet();
}
}
```
Motivation:
The current DnsNameResolver fails to resolve an A+CNAME answer. For example:
dig moose.rmq.cloudamqp.com
...
;; ANSWER SECTION:
moose.rmq.cloudamqp.com. 1800 IN CNAME ec2-54-152-221-139.compute-1.amazonaws.com.
ec2-54-152-221-139.compute-1.amazonaws.com. 583612 IN A 54.152.221.139
...
The resolver constructs a map of cnames but forgets the trailing "." in the values which lead to not resolve the A record.
Modifications:
Reuse the code of DefaltDnsRecordDecoder which correctly handles the trailing dot.
Result:
Correctly resolve.
Related: #4333#4421#5128
Motivation:
slice(), duplicate() and readSlice() currently create a non-recyclable
derived buffer instance. Under heavy load, an application that creates a
lot of derived buffers can put the garbage collector under pressure.
Modifications:
- Add the following methods which creates a non-recyclable derived buffer
- retainedSlice()
- retainedDuplicate()
- readRetainedSlice()
- Add the new recyclable derived buffer implementations, which has its
own reference count value
- Add ByteBufHolder.retainedDuplicate()
- Add ByteBufHolder.replace(ByteBuf) so that..
- a user can replace the content of the holder in a consistent way
- copy/duplicate/retainedDuplicate() can delegate the holder
construction to replace(ByteBuf)
- Use retainedDuplicate() and retainedSlice() wherever possible
- Miscellaneous:
- Rename DuplicateByteBufTest to DuplicatedByteBufTest (missing 'D')
- Make ReplayingDecoderByteBuf.reject() return an exception instead of
throwing it so that its callers don't need to add dummy return
statement
Result:
Derived buffers are now recycled when created via retainedSlice() and
retainedDuplicate() and derived from a pooled buffer
Motivation:
Some codecs should be considered unstable as these are relative new. For this purpose we should introduce an annotation which these codecs should us to be marked as unstable in terms of API.
Modifications:
- Add UnstableApi annotation and use it on codecs that are not stable
- Move http2.hpack to http2.internal.hpack as it is internal.
Result:
Better document unstable APIs.
Motivation:
- The decoded name should always end with a dot (.), but we currently
strip it, which is incorrect.
- (O) 0 -> "."
- (X) 0 -> ""
- (O) 5 netty 2 io 0 -> "netty.io."
- (X) 5 netty 2 io 0 -> "netty.io"
- The encoded name should end with a null-label, which is a label whose
length is 0, but we currently append an extra NUL, causing FORMERR(1)
on a strict DNS server:
- (O) . -> 0
- (X) . -> 0 0
- (O) netty.io. -> 5 netty 2 io 0
- (X) netty.io. -> 5 netty 2 io 0 0
Modifications:
- Make sure to append '.' when decoding a name.
- Improve index checks so that the decoder can raise
CorruptFrameException instead of IIOBE
- Do not encode extra NUL
- Add more tests
Result:
Robustness and correctness
Motivation:
Zero-length names needs to be "prefixed" by the length as well when encoded into a ByteBuf. Also some servers not correctly prefix these so we should ensure we can workaround this and even decode in such case.
Modifications:
- Always encode the length of the name into the ByteBuf even if its zero-length.
- If there are no readable bytes for the name just asume its an empty name to workaround dns servers that not fully respect the RFC.
Result:
Correctly encode zero-length names and be able to decode empty names even when the rfc is not strictly followed.
Motivation:
Compile crash w/ JDK8:
```
[ERROR]
/Users/slandelle/Documents/dev/workspaces/workspace-ahc2/async-http-clie
nt-project/netty-bp/codec-dns/src/main/java/io/netty/handler/codec/dns/D
nsMessageUtil.java:[176,16] reference to append is ambiguous
both method append(java.lang.String) in java.lang.StringBuilder and
method append(java.lang.StringBuffer) in java.lang.StringBuilder match
```
Modification:
Force type explicitly
Result:
Class compile w/ JDK8
Motivation:
We need to handle the trailing dot in the correct manner when creating DNS questions and responses.
Modifications:
- Add a trailing dot if not given to the hostname when construct a AbstractDnsRecord (this is the same as dig does).
Result:
Correctly handle trailing dots.
Motivation:
Domain name labels must be converted to ASCII and not be longer then 63 chars.
Modifications:
Correctly convert to ASCII which also will enforce the 63 chars length.
Result:
Correctly guard against invalid input.
Motivation:
The current implementation will provide a DnsRawRecord, which, while
containing the host name it resolves to, would require the user to
decode the name using the decode method currently private to
DefaultDnsRecordDecoder, which in fact means copying it.
Modifications:
Introduce DnsPtrRecord, which is a specialization of DnsRecord which
provides a decoded host name.
Result:
PTR Records are much easier to work with, as the name is decoded already.
Motivation:
codec-dns has great function to solve dns packet, but only make a query, not answer query from other client.
i make a change of add two classes to fill last pieces of map, finish the server function.
Modifications:
in this change, add two classes of DatagramDnsQueryDecoder and DatagramDnsResponseEncoder to handle client query, reply answer.
Result:
nothing code change after this commit, except two new classes.
Related issues:
- #3971
- #3973
- #3976
- #4035
Motivation:
1. Previously, DnsNameResolver.query() retried the request query by its
own. It prevents a user from deciding when to retry or stop. It is also
impossible to get the response object whose code is not NOERROR.
2. NameResolver does not have an operation that resolves a host name
into multiple addresses, like InetAddress.getAllByName()
Modifications:
- Changes related with DnsNameResolver.query()
- Make query() not retry
- Move the retry logic to DnsNameResolver.resolve() instead.
- Make query() fail the promise only when I/O error occurred or it
failed to get a response
- Add DnsNameResolverException and use it when query() fails so that
the resolver can give more information about the failure
- query() does not cache anymore.
- Changes related with NameResolver.resolveAll()
- Add NameResolver.resolveAll()
- Add SimpleNameResolver.doResolveAll()
- Changes related with DnsNameResolver.resolve() and resolveAll()
- Make DnsNameResolveContext abstract so that DnsNameResolver can
decide to get single or multiple addresses from it
- Re-implement cache so that the cache works for resolve() and
resolveAll()
- Add 'traceEnabled' property to enable/disable trace information
- Miscellaneous changes
- Use ObjectUtil.checkNotNull() wherever possible
- Add InternetProtocolFamily.addressType() to remove repetitive
switch-case blocks in DnsNameResolver(Context)
- Do not raise an exception when decoding a truncated DNS response
Result:
- Full control over query()
- A user can now retrieve all addresses via (Dns)NameResolver.resolveAll()
- DNS cache works only for resolve() and resolveAll() now.
Motivation:
ResourceLeak.close() must be called when a reference-counted resource is
deallocated, but AbstractDnsMessage.deallocate() forgot to call it.
Modifications:
Call ResourceLeak.close() for the tracked AbstractDnsMessage instances
Result:
Fix the false resource leak warnings
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
Motivation:
DnsQueryEncoder does not encode the 'additional resources' section at all, which contains the pseudo-RR as defined in RFC 2671.
Modifications:
- Modify DnsQueryEncoder to encode the additional resources
- Fix a bug in DnsQueryEncoder where an empty name is encoded incorrectly
Result:
A user can send an EDNS query.
Motivation:
There were two buffer leaks in the codec-dns.
Modifications:
- Fix buffer leak in DnsResponseTest.readResponseTest()
- Correctly release DnsResources on Exception
Result:
No more buffer leaks in the codec-dns module.
Motivation:
DnsResource.duplicate() should return DnsResource and not ByteBufHolder
Modifications:
Change return type from ByteBufHolder to DnsResource
Result:
No need to cast to the correct type when using duplicate()
Related issue: #2688
- DnsClass and DnsType
- Make DnsClass and DnsType implement Comparable
- Optimize the message generation of IllegalArgumentException,
by pre-populating the list of the expected parameters
- Move the static methods up
- Relax the validation rule of DnsClass so that a user can define a
CLASS which is not listed in the RFC 1035
- valueOf(int) does not throw IllegalArgumentException anymore as long
as the specified value is an unsigned short.
- Rename create() and forName() to valueOf() so that they look like a
real enum
- Rename type() and clazz() to intValue() so that they conform to our
naming convention
- Add missing null checks in DnsEntry
Motivation:
DNS class and type were represented as integers rather than an enum or a
similar dedicated value type. This can be a potential source of a
parameter order bug which might be difficult to track down.
Modifications:
Add DnsClass and DnsType to replace integer parameters
Result:
Type safety and less error-proneness
Motivation:
When decoding the NAME field in a DNS Resource Record, DnsResponseDecoder
can raise a NullPointerException if the NAME field contains a loop.
Modification:
Instead of raising an NPE, raise CorruptedFrameException so that the
exception itself has meaning.
Result:
Less confusing when a malformed DNS RR is received
Motivation:
NullPointerException is raised when a DNS response conrains a resource
record whose NAME is empty, which is the case for the authority section.
Modification:
Allow an empty name for DnsEntry. Only disallow an empty name for
DnsQuestion.
Result:
Fixes#2686
Motivation:
DNS packets that contain pointers in a loop will cause
DnsResponseDecoder.readName() to infinite loop.
Modifications:
Fixed DnsResponseDecoder.readName() to detect when packets have loops
and return null instead.
Result:
It is no longer possible to cause Netty to infinite loop by sending it malformed
DNS packets with a loop.
Motivation:
As part of GSOC 2013 we had @mbakkar working on a DNS codec but did not integrate it yet as it needs some cleanup. This commit is based on @mbakkar's work and provide the codec for DNS.
Modifications:
Add DNS codec
Result:
Reusable DNS codec will be included in netty.
This PR also includes a AsynchronousDnsResolver which allows to resolve DNS entries in a non blocking way by make use
of the dns codec and netty transport itself.
