Support TCP Fast Open for clients and make SslHandler take advantage
Motivation:
- TCP Fast Open allow us to send a small amount of data along side the initial SYN packet when establishing a TCP connection.
- The TLS Client Hello packet is small enough to fit in there, and is also idempotent (another requirement for using TCP Fast Open), so if we can save a round-trip when establishing TLS connections when using TFO.
Modification:
- Add support for client-side TCP Fast Open for Epoll, and also lowers the Linux kernel version requirements to 3.6.
- When adding the SslHandler to a pipeline, if TCP Fast Open is enabled for the channel (and the channel is not already active) then start the handshake early by writing it to the outbound buffer.
- An important detail to note here, is that the outbound buffer is not flushed at this point, like it would for normal handshakes. The flushing happens later as part of establishing the TCP connection.
Result:
- It is now possible for clients (on epoll) to open connections with TCP Fast Open.
- The SslHandler automatically detects when this is the case, and now send its Client Hello message as part of the initial data in the TCP Fast Open flow when available, saving a round-trip when establishing TLS connections.
Co-authored-by: Colin Godsey <crgodsey@gmail.com>
Motivation:
File.createTempFile(String, String)` will create a temporary file in the system temporary directory if the 'java.io.tmpdir'. The permissions on that file utilize the umask. In a majority of cases, this means that the file that java creates has the permissions: `-rw-r--r--`, thus, any other local user on that system can read the contents of that file.
This can be a security concern if any sensitive data is stored in this file.
This was reported by Jonathan Leitschuh <jonathan.leitschuh@gmail.com> as a security problem.
Modifications:
Use Files.createTempFile(...) which will use safe-defaults when running on java 7 and later. If running on java 6 there isnt much we can do, which is fair enough as java 6 shouldnt be considered "safe" anyway.
Result:
Create temporary files with sane permissions by default.
Motivation:
We need to ensure we copy the attributes and options when bootstrap the channel as otherwise we may change the underlying Entry.
This is similar to what was reported in https://github.com/netty/netty-incubator-codec-quic/issues/152.
Modifications:
- Do a copy and re-use methods
- Add unit tests
Result:
Don't affect attributes / options of channels that are already bootstrapped
Motivation:
https in xmlns URIs does not work and will let the maven release plugin fail:
```
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.779 s
[INFO] Finished at: 2020-11-10T07:45:21Z
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.5.3:prepare (default-cli) on project netty-parent: Execution default-cli of goal org.apache.maven.plugins:maven-release-plugin:2.5.3:prepare failed: The namespace xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" could not be added as a namespace to "project": The namespace prefix "xsi" collides with an additional namespace declared by the element -> [Help 1]
[ERROR]
```
See also https://issues.apache.org/jira/browse/HBASE-24014.
Modifications:
Use http for xmlns
Result:
Be able to use maven release plugin
Motivation:
Allowing null handlers allows for more convenient idioms in
conditionally adding handlers, e.g.,
ch.pipeline().addLast(
new FooHandler(),
condition ? new BarHandler() : null,
new BazHandler()
);
Modifications:
* Change addFirst(..) and addLast(..) to skip null handlers, rather than
break or short-circuit.
* Add new unit tests.
Result:
* Makes addFirst(..) and addLast(..) behavior more consistent
* Resolves https://github.com/netty/netty/issues/10728
Motivation:
`DefaultChannelId` uses reflection to access the JMX runtime. This needs some extra config for GraalVM.
Modification:
Add config for GraalVM
Result:
Works when using GraalVM native image
Motivation:
During the last few month we did develop an io_uring based transport which shows very promising performance numbers. To give it more time to bake we will develop it outside of netty in an "incubator" module which will make it clear to users what to expect and also allow us to seperate its release cycle. While the implementation of it is very self contained there are few small adjustments that need to be made in netty itself to allow us to reuse code.
Modifications:
- AbstractChannel: Add method which can be used when a write fails and remove final from one method
- IovArray: Allow to create an IovArray from a ByteBuf instance
- FileDescriptor: Allow to reuse mark close logic via sub-class
Result:
Be able to reuse netty core classes in io_uring incubator repository
Motivation:
We should preferable always release the message before we notify the promise. Thhis has a few advantages:
- Release memory as soon as possible
- Listeners observe the "more correct" reference count
Modifications:
Release message before fail the promises
Result:
Faster releasing of resources. This came up in https://github.com/netty/netty/issues/10723
Motivation:
Since GraalVM version 19.3.0, instances of java.net.InetAddress (and its subclasses Inet4Address and Inet6Address) are not allowed in native image heap (that is, they cannot be stored in static fields of classes initialized at build time or be reachable through static fields of such classes). When building a native image, it makes sense to initialize at build time as many classes as possible.
But some fields of some classes in Netty (for example, NetUtil.LOCALHOST4) contain InetAddress instances. If a program is using code path that makes it possible to reach such fields at build time initialization, it becomes impossible to build a native image initializing core Netty classes initialized at runtime. An example of such a program is a client that uses netty-dns.
Modifications:
- Add netty-testsuite-native-image-client Maven module to test that such an example program can be built after the corresponding fixes
- Add native-image.properties to resolver-dns module to move initialization of some classes to runtime (some of them are parsing configuration during initialization, so it makes no sense to initialize them at build time; for others, it's needed to avoid InetAddress reachability at build time)
- Add substitutions for NetUtil.LOCALHOST4, NetUtil.LOCALHOST6 and NetUtil.LOCALHOST to overcome the InetAddress-related prohibition
- Extract some initialization code from NetUtil to NetUtilInitializations to allow it to be used by the substitutions
Result:
A client program using netty-dns with --initialize-at-build-time=io.netty builds successfully
Motivation:
Thread.stop() works by producing a ThreadDeath error in the target thread. EventLoops swallow all Throwables, which makes them effectively unkillable. This is effectively a memory leak, for our application. Beside this we should also just regrow all `Error` as there is almost no way to recover.
Modification:
Edit the EventLoops that swallow Throwables to instead rethrow Error.
Result:
`EventLoop` can crash if `Error` is thrown
Motivation:
HTTP is a plaintext protocol which means that someone may be able
to eavesdrop the data. To prevent this, HTTPS should be used whenever
possible. However, maintaining using https:// in all URLs may be
difficult. The nohttp tool can help here. The tool scans all the files
in a repository and reports where http:// is used.
Modifications:
- Added nohttp (via checkstyle) into the build process.
- Suppressed findings for the websites
that don't support HTTPS or that are not reachable
Result:
- Prevent using HTTP in the future.
- Encourage users to use HTTPS when they follow the links they found in
the code.
Motivation:
I was collecting stats for failed promises with a FixedChannelPool and I was bucketing by stats using cause.getSimpleName(). After #9152 was released, the introduction of the anonymous classes make getSimpleName() return "" causing confusion.
Modification:
Use named classes in the ChannelPool implementations. I made them private, but I can change that if you think otherwise.
Result:
The SimpleChannelPool fails the promises with a ChannelPoolFullException. The FixedChannelPool fails the promises with an AcquireTimeoutException. Also AcquireTimeoutException is more specific than just a plain TimeoutException, which is also useful for troubleshooting. If you want different class names, please advise.
Motivation:
DuplexChannel allow for half-closure, we should have a special config interface for it as well.
Modifications:
Add DuplexChannelConfig which allows to configure half-closure.
Result:
More consistent types
Motivation:
junit deprecated Assert.assertThat(...)
Modifications:
Use MatcherAssert.assertThat(...) as replacement for deprecated method
Result:
Less deprecation warnings
Motivation:
LGTM reports multiple issues. They need to be triaged,
and real ones should be fixed.
Modifications:
- Fixed multiple issues reported by LGTM, such as redundant conditions,
resource leaks, typos, possible integer overflows.
- Suppressed false-positives.
- Added a few testcases.
Result:
Fixed several possible issues, get rid of false alarms in the LGTM report.
Motivation:
We have a few classes in which we store and reuse static instances of various exceptions. When doing so it is important to also override fillInStacktrace() and so prevent the leak of the ClassLoader in the internal backtrace field.
Modifications:
- Add overrides of fillInStracktrace when needed
- Move ThrowableUtil usage in the static methods
Result:
Fixes https://github.com/netty/netty/pull/10686
Motivation:
We should use an initial buffer size with is >= 1500 (which is a common setting for MTU) to reduce the need for memory copies when a new connection is established. This is especially interesting when SSL / TLS comes into the mix.
This was ported from swiftnio:
https://github.com/apple/swift-nio/pull/1641
Modifications:
Increase the initial size from 1024 to 2048.
Result:
Possible less memory copies on new connections
Motivation:
Creating exceptions is expensive so we should only do so if really needed.
Modifications:
Only create the ConnectTimeoutException if we really need it.
Result:
Less overhead
Motivation:
In some benchmarks closing the Channel attributes to a lot of overhead due the call of fillInStackTrace(). We should reduce this overhead.
Modifications:
- Create a StacklessClosedChannelException and use it to reduce overhead.
- Only call ChannelOutboundBuffer.failFlushed(...) when there was a flushed message at all.
Result:
Less performance overhead when closing the Channel
Motivation:
I was working on the transport part in Netty (ofc, solving a major issue) and I found this typo so thought to fix it.
Modification:
Fixed Typo
Result:
No more confusion between `us` and `use`.
Motivation:
At some point a ChannelHandlerContext did have its own AttributeMap which is not true since 4.1.x was released. Unfortunally we missed to update the javadocs and so these don't reflect reality
Modifications:
Update javadocs
Result:
Fixes https://github.com/netty/netty/issues/10477
Motivation:
When we were using the netty http protocol, OOM occurred, this problem has been in 4.1.51.Final Fix [# 10424](https://github.com/netty/netty/issues/10424), even if OOM is up, the service will still receive new connection events, will occur again OOM and eventually cause the connection not to be released.
code `byteBuf = allocHandle.allocate(allocator);`
Modification:
I fail to create buffer when I try to receive new data, i determine if it is OOM then the close read event releases the connection.
```java
if (close || cause instanceof OutOfMemoryError || cause instanceof IOException) {
closeOnRead(pipeline);
}
```
Result:
Fixes # [10434](https://github.com/netty/netty/issues/10434).
Motivation:
When a switch statement is used we should always define a `default:` so we don't introduce bugs due fall-through.
Modification:
Add missing `default:`s
Result:
Less error-prone code
Motivation:
Seems like some users are suprised by the behaviour of DefaultEventExecutor when used within the ChannelPipeline. We should clarify the semantics and also mention UnordedThreadPoolEventExecutor which may be more inline with their expectations
Modifications:
Add javadocs section about UnorderedThreadPoolEventExecutor and expand details for DefaultEventExecutor
Result:
Clarify sematics
Motivation:
AbstractCoalescingBufferQueue had a bug which could lead to an empty queue while still report bytes left. This was due the fact that we decremented the pending bytes before draining the queue one-by-one. The problem here is that while the queue is drained we may notify the promise which may add again buffers to the queue for which we never decrement the bytes while we drain these
Modifications:
- Decrement the pending bytes every time we drain a buffer from the queue
- Add unit tests
Result:
Fixes https://github.com/netty/netty/issues/10286
