* Introduction of Happy Eyeballs Version 2 (RFC8305) in Socket.tcp
This is an implementation of Happy Eyeballs version 2 (RFC 8305) in Socket.tcp.
[Background]
Currently, `Socket.tcp` synchronously resolves names and makes connection attempts with `Addrinfo::foreach.`
This implementation has the following two problems.
1. In name resolution, the program stops until the DNS server responds to all DNS queries.
2. In a connection attempt, while an IP address is trying to connect to the destination host and is taking time, the program stops, and other resolved IP addresses cannot try to connect.
[Proposal]
"Happy Eyeballs" ([RFC 8305](https://datatracker.ietf.org/doc/html/rfc8305)) is an algorithm to solve this kind of problem. It avoids delays to the user whenever possible and also uses IPv6 preferentially.
I implemented it into `Socket.tcp` by using `Addrinfo.getaddrinfo` in each thread spawned per address family to resolve the hostname asynchronously, and using `Socket::connect_nonblock` to try to connect with multiple addrinfo in parallel.
[Outcome]
This change eliminates a fatal defect in the following cases.
Case 1. One of the A or AAAA DNS queries does not return
---
require 'socket'
class Addrinfo
class << self
# Current Socket.tcp depends on foreach
def foreach(nodename, service, family=nil, socktype=nil, protocol=nil, flags=nil, timeout: nil, &block)
getaddrinfo(nodename, service, Socket::AF_INET6, socktype, protocol, flags, timeout: timeout)
.concat(getaddrinfo(nodename, service, Socket::AF_INET, socktype, protocol, flags, timeout: timeout))
.each(&block)
end
def getaddrinfo(_, _, family, *_)
case family
when Socket::AF_INET6 then sleep
when Socket::AF_INET then [Addrinfo.tcp("127.0.0.1", 4567)]
end
end
end
end
Socket.tcp("localhost", 4567)
---
Because the current `Socket.tcp` cannot resolve IPv6 names, the program stops in this case. It cannot start to connect with IPv4 address.
Though `Socket.tcp` with HEv2 can promptly start a connection attempt with IPv4 address in this case.
Case 2. Server does not promptly return ack for syn of either IPv4 / IPv6 address family
---
require 'socket'
fork do
socket = Socket.new(Socket::AF_INET6, :STREAM)
socket.setsockopt(:SOCKET, :REUSEADDR, true)
socket.bind(Socket.pack_sockaddr_in(4567, '::1'))
sleep
socket.listen(1)
connection, _ = socket.accept
connection.close
socket.close
end
fork do
socket = Socket.new(Socket::AF_INET, :STREAM)
socket.setsockopt(:SOCKET, :REUSEADDR, true)
socket.bind(Socket.pack_sockaddr_in(4567, '127.0.0.1'))
socket.listen(1)
connection, _ = socket.accept
connection.close
socket.close
end
Socket.tcp("localhost", 4567)
---
The current `Socket.tcp` tries to connect serially, so when its first name resolves an IPv6 address and initiates a connection to an IPv6 server, this server does not return an ACK, and the program stops.
Though `Socket.tcp` with HEv2 starts to connect sequentially and in parallel so a connection can be established promptly at the socket that attempted to connect to the IPv4 server.
In exchange, the performance of `Socket.tcp` with HEv2 will be degraded.
---
100.times { Socket.tcp("www.ruby-lang.org", 80) }
---
This is due to the addition of the creation of IO objects, Thread objects, etc., and calls to `IO::select` in the implementation.
* Avoid NameError of Socket::EAI_ADDRFAMILY in MinGW
* Support Windows with SO_CONNECT_TIME
* Improve performance
I have additionally implemented the following patterns:
- If the host is single-stack, name resolution is performed in the main thread. This reduces the cost of creating threads.
- If an IP address is specified, name resolution is performed in the main thread. This also reduces the cost of creating threads.
- If only one IP address is resolved, connect is executed in blocking mode. This reduces the cost of calling IO::select.
Also, I have added a fast_fallback option for users who wish not to use HE.
Here are the results of each performance test.
```ruby
require 'socket'
require 'benchmark'
HOSTNAME = "www.ruby-lang.org"
PORT = 80
ai = Addrinfo.tcp(HOSTNAME, PORT)
Benchmark.bmbm do |x|
x.report("Domain name") do
30.times { Socket.tcp(HOSTNAME, PORT).close }
end
x.report("IP Address") do
30.times { Socket.tcp(ai.ip_address, PORT).close }
end
x.report("fast_fallback: false") do
30.times { Socket.tcp(HOSTNAME, PORT, fast_fallback: false).close }
end
end
```
```
user system total real
Domain name 0.015567 0.032511 0.048078 ( 0.325284)
IP Address 0.004458 0.014219 0.018677 ( 0.284361)
fast_fallback: false 0.005869 0.021511 0.027380 ( 0.321891)
````
And this is the measurement result when executed in a single stack environment.
```
user system total real
Domain name 0.007062 0.019276 0.026338 ( 1.905775)
IP Address 0.004527 0.012176 0.016703 ( 3.051192)
fast_fallback: false 0.005546 0.019426 0.024972 ( 1.775798)
```
The following is the result of the run on Ruby 3.3.0.
(on Dual stack environment)
```
user system total real
Ruby 3.3.0 0.007271 0.027410 0.034681 ( 0.472510)
```
(on Single stack environment)
```
user system total real
Ruby 3.3.0 0.005353 0.018898 0.024251 ( 1.774535)
```
* Do not cache `Socket.ip_address_list`
As mentioned in the comment at https://github.com/ruby/ruby/pull/9374#discussion_r1482269186, caching Socket.ip_address_list does not follow changes in network configuration.
But if we stop caching, it becomes necessary to check every time `Socket.tcp` is called whether it's a single stack or not, which could further degrade performance in the case of a dual stack.
From this, I've changed the approach so that when a domain name is passed, it doesn't check whether it's a single stack or not and resolves names in parallel each time.
The performance measurement results are as follows.
require 'socket'
require 'benchmark'
HOSTNAME = "www.ruby-lang.org"
PORT = 80
ai = Addrinfo.tcp(HOSTNAME, PORT)
Benchmark.bmbm do |x|
x.report("Domain name") do
30.times { Socket.tcp(HOSTNAME, PORT).close }
end
x.report("IP Address") do
30.times { Socket.tcp(ai.ip_address, PORT).close }
end
x.report("fast_fallback: false") do
30.times { Socket.tcp(HOSTNAME, PORT, fast_fallback: false).close }
end
end
user system total real
Domain name 0.004085 0.011873 0.015958 ( 0.330097)
IP Address 0.000993 0.004400 0.005393 ( 0.257286)
fast_fallback: false 0.001348 0.008266 0.009614 ( 0.298626)
* Wait forever if fallback addresses are unresolved, unless resolv_timeout
Changed from waiting only 3 seconds for name resolution when there is no fallback address available, to waiting as long as there is no resolv_timeout.
This is in accordance with the current `Socket.tcp` specification.
* Use exact pattern to match IPv6 address format for specify address family
When making an outgoing TCP or UDP connection, set AI_ADDRCONFIG in the
hints we send to getaddrinfo(3) (if supported). This will prompt the
resolver to _NOT_ issue A or AAAA queries if the system does not
actually have an IPv4 or IPv6 address (respectively).
This makes outgoing connections marginally more efficient on
non-dual-stack systems, since we don't have to try connecting to an
address which can't possibly work.
More importantly, however, this works around a race condition present
in some older versions of glibc on aarch64 where it could accidently
send the two outgoing DNS queries with the same DNS txnid, and get
confused when receiving the responses. This manifests as outgoing
connections sometimes taking 5 seconds (the DNS timeout before retry) to
be made.
Fixes#19144
The test for Socket::ResolutionError#error_code fails in the FreeBSD environment with this test condition. Because Socket::ResolutionError#error_code returns Socket::EAI_FAIL instead of Socket::EAI_FAMILY.
20231130T103002Z.fail.html.gz
This PR avoids the test failure by relaxing the condition.
Also changed the domain for testing to `example.com`.
Since Linux 4.5, sendmsg(2) fails with ETOOMANYREFS if the number of
"in-flight" IOs, which has been sent by sendmsg(2) but has not yet
accepted by recvmsg(2), exceeds the RLIMIT_NOFILE resource limit.
20231025T090004Z.fail.html.gz
```
1) Error:
TestSocket_UNIXSocket#test_fd_passing_race_condition:
Errno::ETOOMANYREFS: Too many references: cannot splice - sendmsg(2)
```
This change reduces the number of times of IO passing under 1024,
which is a default limit in many environments.
OpenBSD and Solaris behave differently here.
Linux does deliver the empty packet, which is questionable
as it's undistinguishable from a closed connection.
It seems that OpenBSD and Solaris simply drop it.
We could test the platform before doing the assertion, but
it would likely be fragile, and the entire web recommend
to not ever send an empty packet, so the value of this
assertion is low.
[Bug #19012]
man recvmsg(2) states:
> Return Value
> These calls return the number of bytes received, or -1 if an error occurred.
> The return value will be 0 when the peer has performed an orderly shutdown.
Not too sure how one is supposed to make the difference between a packet of
size 0 and a closed connection.
* Windows: Fix warning about undefined if_indextoname()
* Windows: Fix UNIXSocket on MINGW and make .pair more reliable
* Windows: Use nonblock=true for read tests with scheduler
* Windows: Move socket detection from File.socket? to File.stat
Add S_IFSOCK to Windows and interpret reparse points accordingly.
Enable tests that work now.
* Windows: Use wide-char functions to UNIXSocket
This fixes behaviour with non-ASCII characters.
It also fixes deletion of temporary UNIXSocket.pair files.
* Windows: Add UNIXSocket tests for specifics of Windows impl.
* Windows: fix VC build due to missing _snwprintf
Avoid usage of _snwprintf, since it fails linking ruby.dll like so:
linking shared-library x64-vcruntime140-ruby320.dll
x64-vcruntime140-ruby320.def : error LNK2001: unresolved external symbol snwprintf
x64-vcruntime140-ruby320.def : error LNK2001: unresolved external symbol vsnwprintf_l
whereas linking miniruby.exe succeeds.
This patch uses snprintf on the UTF-8 string instead.
Also remove branch GetWindowsDirectoryW, since it doesn't work.
* Windows: Fix dangling symlink test failures
Co-authored-by: Lars Kanis <kanis@comcard.de>
The test fails on Solaris 10. Maybe due to the IPv6 configuration on the
server, but I have no idea at all. I've asked @ngoto to investigate the
issue, so will tentatively skip the tests on Solaris
20210729T040002Z.fail.html.gz
because the name "MJIT" is an internal code name, it's inconsistent with
--jit while they are related to each other, and I want to discourage future
JIT implementation-specific (e.g. MJIT-specific) APIs by this rename.
[Feature #17490]
getaddrinfo_a() gets stuck after fork().
To avoid this, we need 1 second sleep to wait for internal
worker threads of getaddrinfo_a() to be finished, but that is unacceptable.
[Bug #17220] [Feature #17134] [Feature #17187]
We need stop worker threads in getaddrinfo_a() before fork().
This change adds a hook before fork() that cancel all outstanding requests
and wait for all ongoing requests. Then, it waits for all worker
threads to be finished.
Fixes [Bug #17220]
Receiving UnixSocket works fine if you don't provide a mode, and
I think it is reasonable to expect that you should not provide
a mode if klass.for_fd would not accept a mode.
Fixes [Bug #11778]
Before, Socket.getaddrinfo was using a blocking getaddrinfo(3) call.
That didn't allow to wrap it into Timeout.timeout or interrupt the thread in any way.
Combined with the default 10 sec resolv timeout on many Unix systems, this can
have a very noticeable effect on production Ruby apps being not
resilient to DNS outages and timing out name resolution, and being unable to fail fast even
with Timeout.timeout.
Since we already have support for getaddrinfo_a(3), the async version
of getaddrinfo, we should be able to make Socket.getaddrinfo leverage that
when getaddrinfo_a version is available in the system (hence #ifdef
HAVE_GETADDRINFO_A).
Related tickets:
https://bugs.ruby-lang.org/issues/16476https://bugs.ruby-lang.org/issues/16381https://bugs.ruby-lang.org/issues/14997
