1// Copyright 2012 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
5//go:build aix || darwin || dragonfly || freebsd || netbsd || openbsd || solaris || windows
6// +build aix darwin dragonfly freebsd netbsd openbsd solaris windows
7
8package ipv4
9
10import (
11	"errors"
12	"net"
13	"unsafe"
14
15	"golang.org/x/net/internal/socket"
16)
17
18var errNoSuchInterface = errors.New("no such interface")
19
20func (so *sockOpt) setIPMreq(c *socket.Conn, ifi *net.Interface, grp net.IP) error {
21	mreq := ipMreq{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
22	if err := setIPMreqInterface(&mreq, ifi); err != nil {
23		return err
24	}
25	b := (*[sizeofIPMreq]byte)(unsafe.Pointer(&mreq))[:sizeofIPMreq]
26	return so.Set(c, b)
27}
28
29func (so *sockOpt) getMulticastIf(c *socket.Conn) (*net.Interface, error) {
30	var b [4]byte
31	if _, err := so.Get(c, b[:]); err != nil {
32		return nil, err
33	}
34	ifi, err := netIP4ToInterface(net.IPv4(b[0], b[1], b[2], b[3]))
35	if err != nil {
36		return nil, err
37	}
38	return ifi, nil
39}
40
41func (so *sockOpt) setMulticastIf(c *socket.Conn, ifi *net.Interface) error {
42	ip, err := netInterfaceToIP4(ifi)
43	if err != nil {
44		return err
45	}
46	var b [4]byte
47	copy(b[:], ip)
48	return so.Set(c, b[:])
49}
50
51func setIPMreqInterface(mreq *ipMreq, ifi *net.Interface) error {
52	if ifi == nil {
53		return nil
54	}
55	ifat, err := ifi.Addrs()
56	if err != nil {
57		return err
58	}
59	for _, ifa := range ifat {
60		switch ifa := ifa.(type) {
61		case *net.IPAddr:
62			if ip := ifa.IP.To4(); ip != nil {
63				copy(mreq.Interface[:], ip)
64				return nil
65			}
66		case *net.IPNet:
67			if ip := ifa.IP.To4(); ip != nil {
68				copy(mreq.Interface[:], ip)
69				return nil
70			}
71		}
72	}
73	return errNoSuchInterface
74}
75
76func netIP4ToInterface(ip net.IP) (*net.Interface, error) {
77	ift, err := net.Interfaces()
78	if err != nil {
79		return nil, err
80	}
81	for _, ifi := range ift {
82		ifat, err := ifi.Addrs()
83		if err != nil {
84			return nil, err
85		}
86		for _, ifa := range ifat {
87			switch ifa := ifa.(type) {
88			case *net.IPAddr:
89				if ip.Equal(ifa.IP) {
90					return &ifi, nil
91				}
92			case *net.IPNet:
93				if ip.Equal(ifa.IP) {
94					return &ifi, nil
95				}
96			}
97		}
98	}
99	return nil, errNoSuchInterface
100}
101
102func netInterfaceToIP4(ifi *net.Interface) (net.IP, error) {
103	if ifi == nil {
104		return net.IPv4zero.To4(), nil
105	}
106	ifat, err := ifi.Addrs()
107	if err != nil {
108		return nil, err
109	}
110	for _, ifa := range ifat {
111		switch ifa := ifa.(type) {
112		case *net.IPAddr:
113			if ip := ifa.IP.To4(); ip != nil {
114				return ip, nil
115			}
116		case *net.IPNet:
117			if ip := ifa.IP.To4(); ip != nil {
118				return ip, nil
119			}
120		}
121	}
122	return nil, errNoSuchInterface
123}
124