Motivation:
We need limit the number of queries done to resolve unresolved nameserver as otherwise we may never fail the resolve when there is a missconfigured dns server that lead to a "resolve loop".
Modifications:
- When resolve unresolved nameservers ensure we use the allowedQueries as max upper limit for queries so it will eventually fail
- Add unit tests
Result:
No more possibility to fail in a loop while resolve. This is related to https://github.com/netty/netty/issues/10420
Motivation:
DnsAddressResolverGroup allows to be constructed with a DnsNameResolverBuilder and so should respect its configured EventLoop.
Modifications:
- Correctly respect the configured EventLoop
- Ensure there are no thread-issues by calling copy()
- Add unit tests
Result:
Fixes https://github.com/netty/netty/issues/10460
Motivation:
If we cancel the returned future of resolve query, we may get LEAK. Try to release the ByteBuf if netty can't pass the DnsRawRecord to the caller.
Modification:
Using debug mode I saw there are two places that don't handle trySuccess with release. Try to release there.
Result:
Fixes#10447.
Motivation:
There is a possibility to end up with a StackOverflowError when trying to resolve authorative nameservers because of incorrect wrapping the AuthoritativeDnsServerCache.
Modifications:
Ensure we don't end up with an overflow due wrapping
Result:
Fixes https://github.com/netty/netty/issues/10246
Motivation:
Once a CNAME loop was detected we can just fail fast and so reduce the number of queries.
Modifications:
Fail fast once a CNAME loop is detected
Result:
Fail fast
Motivation:
We did use a HashSet to detect CNAME cache loops which needs allocations. We can use an algorithm that doesnt need any allocations
Modifications:
Use algorithm that doesnt need allocations
Result:
Less allocations on the slow path
Motivation:
The nameserver that should / must be used to resolve a CNAME may be different then the nameserver that was selected for the hostname to resolve. Failing to select the correct nameserver may result in problems during resolution.
Modifications:
Use the correct DnsServerAddressStream for CNAMEs
Result:
Always use the correct DnsServerAddressStream for CNAMEs and so fix resolution failures which could accour when CNAMEs are in the mix that use a different domain then the original hostname that we try to resolve
Motivation:
We should only log with warn level if something really critical happens as otherwise we may spam logs and confuse the user.
Modifications:
- Change log level to debug for most cases
Result:
Less noisy logging
Motivation:
We need to detect CNAME loops during lookup the DnsCnameCache as otherwise we may try to follow cnames forever.
Modifications:
- Correctly detect CNAME loops in the cache
- Add unit test
Result:
Fixes https://github.com/netty/netty/issues/10220
Motivations
-----------
DnsNameResolverBuilder and DnsNameResolver do not auto-configure
themselves uing default options define in /etc/resolv.conf.
In particular, rotate, timeout and attempts options are ignored.
Modifications
-------------
- Modified UnixResolverDnsServerAddressStreamProvider to parse ndots,
attempts and timeout options all at once and use these defaults to
configure DnsNameResolver when values are not provided by the
DnsNameResolverBuilder.
- When rotate option is specified, the DnsServerAddresses returned by
UnixResolverDnsServerAddressStreamProvider is rotational.
- Amend resolv.conf options with the RES_OPTIONS environment variable
when present.
Result:
Fixes https://github.com/netty/netty/issues/10202
Motivation:
A user might want to cancel DNS resolution when it takes too long.
Currently, there's no way to cancel the internal DNS queries especially when there's a lot of search domains.
Modification:
- Stop sending a DNS query if the original `Promise`, which was passed calling `resolve()`, is canceled.
Result:
- You can now stop sending DNS queries by cancelling the `Promise`.
Motivation:
Related https://github.com/line/armeria/issues/2463
Here is an example that an NIC has only link local address for IPv6.
```
$ ipaddr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
3: eth0@if18692: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1460 qdisc noqueue
link/ether 1a:5e:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
inet 10.xxx.xxx.xxx/24 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::xxxx:xxxx:xxxx:xxxx/64 scope link
valid_lft forever preferred_lft forever
```
If the NICs have only local or link local addresses, We should not send IPv6 DNS queris.
Modification:
- Ignore link-local IPv6 addresses which may exist even on a machine without IPv6 network.
Result:
- `DnsNameResolver` does not send DNS queries for AAAA when IPv6 is not available.
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
