1// Copyright 2011 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package net
6
7import (
8	"os"
9	"syscall"
10)
11
12func setDefaultSockopts(s syscall.Handle, family, sotype int, ipv6only bool) error {
13	if family == syscall.AF_INET6 && sotype != syscall.SOCK_RAW {
14		// Allow both IP versions even if the OS default
15		// is otherwise. Note that some operating systems
16		// never admit this option.
17		syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, boolint(ipv6only))
18	}
19	if (sotype == syscall.SOCK_DGRAM || sotype == syscall.SOCK_RAW) && family != syscall.AF_UNIX && family != syscall.AF_INET6 {
20		// Allow broadcast.
21		return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1))
22	}
23	return nil
24}
25
26func setDefaultListenerSockopts(s syscall.Handle) error {
27	// Windows will reuse recently-used addresses by default.
28	// SO_REUSEADDR should not be used here, as it allows
29	// a socket to forcibly bind to a port in use by another socket.
30	// This could lead to a non-deterministic behavior, where
31	// connection requests over the port cannot be guaranteed
32	// to be handled by the correct socket.
33	return nil
34}
35
36func setDefaultMulticastSockopts(s syscall.Handle) error {
37	// Allow multicast UDP and raw IP datagram sockets to listen
38	// concurrently across multiple listeners.
39	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1))
40}
41