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core: Refactor listeners; use SO_REUSEPORT on Unix (#4705)

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* core: Refactor listeners; use SO_REUSEPORT on Unix

Just an experiment for now

* Fix lint by logging error

* TCP Keepalive configuration (#4865)

* initial attempt at TCP Keepalive configuration

* core: implement tcp-keepalive for linux

* move canSetKeepAlive interface

* Godoc for keepalive server parameter

* handle return values

* log keepalive errors

* Clean up after bad merge

* Merge in pluggable network types

From 1edc1a45e3aee1f7d86b68c3ddaf2fd16ba8ab73

* Slight refactor, fix from recent merge conflict

Co-authored-by: Karmanyaah Malhotra <karmanyaah.gh@malhotra.cc>
This commit is contained in:
Matt Holt
2022-09-02 16:59:11 -06:00
committed by GitHub
parent 83b26975bd
commit d3c3fa10bd
6 changed files with 234 additions and 138 deletions
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148
listeners.go
View File

@ -24,10 +24,8 @@ import (
"os"
"strconv"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"
"github.com/lucas-clemente/quic-go"
"github.com/lucas-clemente/quic-go/http3"
@ -43,6 +41,14 @@ import (
// the socket have been finished. Always be sure to close listeners
// when you are done with them, just like normal listeners.
func Listen(network, addr string) (net.Listener, error) {
// a 0 timeout means Go uses its default
return ListenTimeout(network, addr, 0)
}
// getListenerFromPlugin returns a listener on the given network and address
// if a plugin has registered the network name. It may return (nil, nil) if
// no plugin can provide a listener.
func getListenerFromPlugin(network, addr string) (net.Listener, error) {
network = strings.TrimSpace(strings.ToLower(network))
// get listener from plugin if network type is registered
@ -51,24 +57,7 @@ func Listen(network, addr string) (net.Listener, error) {
return getListener(network, addr)
}
lnKey := listenerKey(network, addr)
sharedLn, _, err := listenerPool.LoadOrNew(lnKey, func() (Destructor, error) {
ln, err := net.Listen(network, addr)
if err != nil {
// https://github.com/caddyserver/caddy/pull/4534
if isUnixNetwork(network) && isListenBindAddressAlreadyInUseError(err) {
return nil, fmt.Errorf("%w: this can happen if Caddy was forcefully killed", err)
}
return nil, err
}
return &sharedListener{Listener: ln, key: lnKey}, nil
})
if err != nil {
return nil, err
}
return &fakeCloseListener{sharedListener: sharedLn.(*sharedListener)}, nil
return nil, nil
}
// ListenPacket returns a net.PacketConn suitable for use in a Caddy module.
@ -124,80 +113,14 @@ func ListenQUIC(addr string, tlsConf *tls.Config, activeRequests *int64) (quic.E
}, err
}
func listenerKey(network, addr string) string {
return network + "/" + addr
}
// ListenerUsage returns the current usage count of the given listener address.
func ListenerUsage(network, addr string) int {
count, _ := listenerPool.References(listenerKey(network, addr))
return count
}
// fakeCloseListener is a private wrapper over a listener that
// is shared. The state of fakeCloseListener is not shared.
// This allows one user of a socket to "close" the listener
// while in reality the socket stays open for other users of
// the listener. In this way, servers become hot-swappable
// while the listener remains running. Listeners should be
// re-wrapped in a new fakeCloseListener each time the listener
// is reused. This type is atomic and values must not be copied.
type fakeCloseListener struct {
closed int32 // accessed atomically; belongs to this struct only
*sharedListener // embedded, so we also become a net.Listener
}
func (fcl *fakeCloseListener) Accept() (net.Conn, error) {
// if the listener is already "closed", return error
if atomic.LoadInt32(&fcl.closed) == 1 {
return nil, fakeClosedErr(fcl)
}
// call underlying accept
conn, err := fcl.sharedListener.Accept()
if err == nil {
return conn, nil
}
// since Accept() returned an error, it may be because our reference to
// the listener (this fakeCloseListener) may have been closed, i.e. the
// server is shutting down; in that case, we need to clear the deadline
// that we set when Close() was called, and return a non-temporary and
// non-timeout error value to the caller, masking the "true" error, so
// that server loops / goroutines won't retry, linger, and leak
if atomic.LoadInt32(&fcl.closed) == 1 {
// we dereference the sharedListener explicitly even though it's embedded
// so that it's clear in the code that side-effects are shared with other
// users of this listener, not just our own reference to it; we also don't
// do anything with the error because all we could do is log it, but we
// expliclty assign it to nothing so we don't forget it's there if needed
_ = fcl.sharedListener.clearDeadline()
if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
return nil, fakeClosedErr(fcl)
}
}
return nil, err
}
// Close stops accepting new connections without closing the
// underlying listener. The underlying listener is only closed
// if the caller is the last known user of the socket.
func (fcl *fakeCloseListener) Close() error {
if atomic.CompareAndSwapInt32(&fcl.closed, 0, 1) {
// There are two ways I know of to get an Accept()
// function to return to the server loop that called
// it: close the listener, or set a deadline in the
// past. Obviously, we can't close the socket yet
// since others may be using it (hence this whole
// file). But we can set the deadline in the past,
// and this is kind of cheating, but it works, and
// it apparently even works on Windows.
_ = fcl.sharedListener.setDeadline()
_, _ = listenerPool.Delete(fcl.sharedListener.key)
}
return nil
func listenerKey(network, addr string) string {
return network + "/" + addr
}
type fakeCloseQuicListener struct {
@ -283,55 +206,6 @@ func (fcpc fakeClosePacketConn) SyscallConn() (syscall.RawConn, error) {
return nil, fmt.Errorf("SyscallConn() not implemented for %T", fcpc.PacketConn)
}
// sharedListener is a wrapper over an underlying listener. The listener
// and the other fields on the struct are shared state that is synchronized,
// so sharedListener structs must never be copied (always use a pointer).
type sharedListener struct {
net.Listener
key string // uniquely identifies this listener
deadline bool // whether a deadline is currently set
deadlineMu sync.Mutex
}
func (sl *sharedListener) clearDeadline() error {
var err error
sl.deadlineMu.Lock()
if sl.deadline {
switch ln := sl.Listener.(type) {
case *net.TCPListener:
err = ln.SetDeadline(time.Time{})
case *net.UnixListener:
err = ln.SetDeadline(time.Time{})
}
sl.deadline = false
}
sl.deadlineMu.Unlock()
return err
}
func (sl *sharedListener) setDeadline() error {
timeInPast := time.Now().Add(-1 * time.Minute)
var err error
sl.deadlineMu.Lock()
if !sl.deadline {
switch ln := sl.Listener.(type) {
case *net.TCPListener:
err = ln.SetDeadline(timeInPast)
case *net.UnixListener:
err = ln.SetDeadline(timeInPast)
}
sl.deadline = true
}
sl.deadlineMu.Unlock()
return err
}
// Destruct is called by the UsagePool when the listener is
// finally not being used anymore. It closes the socket.
func (sl *sharedListener) Destruct() error {
return sl.Listener.Close()
}
// sharedQuicListener is like sharedListener, but for quic.EarlyListeners.
type sharedQuicListener struct {
quic.EarlyListener