Motivation:
939e928312 introduced MacOSDnsServerAddressStreamProvider which will ensure the right nameservers are selected when running on MacOS. To ensure this is done automatically on MacOS we should use it by default on these platforms.
Modifications:
Try to use MacOSDnsServerAddressStreamProvider when on MacOS via reflection and fallback if not possible
Result:
Ensure the right nameservers are used on MacOS even when a VPN (for example) is used.
Motivation:
In general, we will close the debug log in a product environment. However, logging without external level check may still affect performance as varargs will need to allocate an array.
Modification:
Add log level check simply before logging.
Result:
Improve performance slightly in a product environment.
Motivation:
The resolver API and implementations should be considered stable by now so we should not mark these with @UnstableApi
Modifications:
Remove @UnstableApi annotation from API and implementation of resolver
Result:
Make it explicit that the API is considered stable
Motivation:
The resolv.conf file may contain inline comments which should be ignored
Modifications:
- Detect if we have a comment after the ipaddress and if so skip it
- Add unit test
Result:
Fixes https://github.com/netty/netty/issues/9889
Motivation:
We should just ignore (and so skip) invalid entries in /etc/resolver.conf.
Modifications:
- Skip invalid entries
- Add unit test
Result:
Fix https://github.com/netty/netty/issues/9684
Motivation
A memory leak related to DNS resolution was reported in #9634,
specifically linked to the TCP retry fallback functionality that was
introduced relatively recently. Upon inspection it's apparent that there
are some error paths where the original UDP response might not be fully
released, and more significantly the TCP response actually leaks every
time on the fallback success path.
It turns out that a bug in the unit test meant that the intended TCP
fallback path was not actually exercised, so it did not expose the main
leak in question.
Modifications
- Fix DnsNameResolverTest#testTruncated0 dummy server fallback logic to
first read transaction id of retried query and use it in replayed
response
- Adjust semantic of internal DnsQueryContext#finish method to always
take refcount ownership of passed in envelope
- Reorder some logic in DnsResponseHandler fallback handling to verify
the context of the response is expected, and ensure that the query
response are either released or propagated in all cases. This also
reduces a number of redundant retain/release pairings
Result
Fixes#9634
Motivation:
Classes `AbstractHttp2StreamChannel.Http2StreamChannelConfig`
and `DnsNameResolver.AddressedEnvelopeAdapter` may be static:
it doesn't reference its enclosing instance.
Modification:
Add `static` modifier.
Result:
Prevents a possible memory leak and uses less memory per class instance.
Motivation:
We currently try to access the the domain search list via reflection on windows which will print a illegal access warning when using Java9 and later.
Modifications:
Add a guard against the used java version.
Result:
Fixes https://github.com/netty/netty/issues/9500.
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:
We should only ever close the underlying tcp socket once we received the envelope to ensure we never race in the test.
Modifications:
- Only close socket once we received the envelope
- Set REUSE_ADDR
Result:
More robust test
Motivation:
testTruncatedWithTcpFallback was flacky as we may end up closing the socket before we could read all data. We should only close the socket after we succesfully read all data.
Modifications:
Move socket.close() to finally block
Result:
Fix flaky test and so make the CI more stable again.
Motivation:
We should only try to use reflection to access default nameservers when using Java8 and lower as otherwise we will produce an Illegal reflective access warning like:
WARNING: Illegal reflective access by io.netty.resolver.dns.DefaultDnsServerAddressStreamProvider
Modifications:
Add Java version check before try to use reflective access.
Result:
No more warning when Java9+ is used.
Motivation:
OOME is occurred by increasing suppressedExceptions because other libraries call Throwable#addSuppressed. As we have no control over what other libraries do we need to ensure this can not lead to OOME.
Modifications:
Only use static instances of the Exceptions if we can either dissable addSuppressed or we run on java6.
Result:
Not possible to OOME because of addSuppressed. Fixes https://github.com/netty/netty/issues/9151.
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:
https://github.com/netty/netty/pull/9021 did apply some changes to filter out duplicates InetAddress when calling resolveAll(...) to mimic JDK behaviour. Unfortunally this also introduced a regression as we should not filter duplicates when the user explicit calls resolveAll(DnsQuestion).
Modifications:
- Only filter duplicates if resolveAll(String) is used
- Add unit test
Result:
Fixes regressions introduces by https://github.com/netty/netty/pull/9021
Motivation:
075cf8c02e introduced a change to allow resolve(...) to notify as soon as the preferred record was resolved. This works great but we should also allow the user to configure that we want to do the same for resolveAll(...), which means we should be able to notify as soon as all records for a preferred record were resolved.
Modifications:
- Add a new DnsNameResolverBuilder method to allow configure this (use false as default to not change default behaviour)
- Add unit test
Result:
Be able to speed up resolving.
Motivation:
At the moment resolve(...) does just delegate to resolveAll(...) and so will only notify the future once all records were resolved. This is wasteful as we are only interested in the first record anyway. We should notify the promise as soon as one record that matches the preferred record type is resolved.
Modifications:
- Introduce DnsResolveContext.isCompleteEarly(...) to be able to detect once we should early notify the promise.
- Make use of this early detecting if resolve(...) is called
- Remove FutureListener which could lead to IllegalReferenceCountException due double releases
- add unit test
Result:
Be able to notify about resolved host more quickly.
Motivation:
We did not correctly calculate the new ttl as we did forget to add `this.`
Modifications:
Add .this and so correctly calculate the TTL
Result:
Use correct TTL for authoritative nameservers when updating these.
Motivation:
To closely mimic what the JDK does we should not try to resolve AAAA records if the system itself does not support IPv6 at all as it is impossible to connect to this addresses later on. In this case we need to use ResolvedAddressTypes.IPV4_ONLY.
Modifications:
Add static method to detect if IPv6 is supported and if not use ResolvedAddressTypes.IPV4_ONLY.
Result:
More consistent behaviour between JDK and our resolver implementation.
Motivation:
At the moment we basically drop all non prefered addresses when calling DnsNameResolver.resolveAll(...). This is just incorrect and was introduced by 4cd39cc4b3. More correct is to still retain these but sort the returned List to have the prefered addresses on the beginning of the List. This also ensures resolve(...) will return the correct return type.
Modifications:
- Introduce PreferredAddressTypeComperator which we use to sort the List so it will contain the preferred address type first.
- Add unit test to verify behaviour
Result:
Include not only preferred addresses in the List that is returned by resolveAll(...)
Motivation:
During investigating some other bug I noticed that we log with warn level if we fail to notify the promise due the fact that it is already full-filled. This is not correct and missleading as there is nothing wrong with it in general. A promise may already been fullfilled because we did multiple queries and one of these was successful.
Modifications:
- Change log level to trace
- Add unit test which before did log with warn level but now does with trace level.
Result:
Less missleading noise in the log.
Motivation:
DnsNameResolver#resolveAll(String) may return duplicate results in the event that the original hostname DNS response includes an IP address X and a CNAME that ends up resolving the same IP address X. This behavior is inconsistent with the JDK’s resolver and is unexpected to retrun a List with duplicate entries from a resolveAll(..) call.
Modifications:
- Filter out duplicates
- Add unit test
Result:
More consistent and less suprising behavior
