syncthing/lib/dialer/control_unix.go

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// Copyright (C) 2019 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
//go:build !solaris && !windows
// +build !solaris,!windows
package dialer
import (
"syscall"
"golang.org/x/sys/unix"
)
var SupportsReusePort = false
func init() {
fd, err := unix.Socket(unix.AF_INET, unix.SOCK_STREAM, unix.IPPROTO_IP)
if err != nil {
l.Debugln("Failed to create a socket", err)
return
}
defer func() { _ = unix.Close(fd) }()
err = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
switch {
case err == unix.ENOPROTOOPT || err == unix.EINVAL:
l.Debugln("SO_REUSEPORT not supported")
case err != nil:
l.Debugln("Unknown error when determining SO_REUSEPORT support", err)
default:
l.Debugln("SO_REUSEPORT supported")
SupportsReusePort = true
}
}
func ReusePortControl(_, _ string, c syscall.RawConn) error {
if !SupportsReusePort {
return nil
}
var opErr error
err := c.Control(func(fd uintptr) {
opErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
})
if err != nil {
return err
}
return opErr
}