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