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 darwin dragonfly freebsd netbsd openbsd solaris windows
6
7package ipv4
8
9import (
10	"net"
11	"unsafe"
12
13	"golang.org/x/net/internal/socket"
14)
15
16func (so *sockOpt) setIPMreq(c *socket.Conn, ifi *net.Interface, grp net.IP) error {
17	mreq := ipMreq{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
18	if err := setIPMreqInterface(&mreq, ifi); err != nil {
19		return err
20	}
21	b := (*[sizeofIPMreq]byte)(unsafe.Pointer(&mreq))[:sizeofIPMreq]
22	return so.Set(c, b)
23}
24
25func (so *sockOpt) getMulticastIf(c *socket.Conn) (*net.Interface, error) {
26	var b [4]byte
27	if _, err := so.Get(c, b[:]); err != nil {
28		return nil, err
29	}
30	ifi, err := netIP4ToInterface(net.IPv4(b[0], b[1], b[2], b[3]))
31	if err != nil {
32		return nil, err
33	}
34	return ifi, nil
35}
36
37func (so *sockOpt) setMulticastIf(c *socket.Conn, ifi *net.Interface) error {
38	ip, err := netInterfaceToIP4(ifi)
39	if err != nil {
40		return err
41	}
42	var b [4]byte
43	copy(b[:], ip)
44	return so.Set(c, b[:])
45}
46
47func setIPMreqInterface(mreq *ipMreq, ifi *net.Interface) error {
48	if ifi == nil {
49		return nil
50	}
51	ifat, err := ifi.Addrs()
52	if err != nil {
53		return err
54	}
55	for _, ifa := range ifat {
56		switch ifa := ifa.(type) {
57		case *net.IPAddr:
58			if ip := ifa.IP.To4(); ip != nil {
59				copy(mreq.Interface[:], ip)
60				return nil
61			}
62		case *net.IPNet:
63			if ip := ifa.IP.To4(); ip != nil {
64				copy(mreq.Interface[:], ip)
65				return nil
66			}
67		}
68	}
69	return errNoSuchInterface
70}
71
72func netIP4ToInterface(ip net.IP) (*net.Interface, error) {
73	ift, err := net.Interfaces()
74	if err != nil {
75		return nil, err
76	}
77	for _, ifi := range ift {
78		ifat, err := ifi.Addrs()
79		if err != nil {
80			return nil, err
81		}
82		for _, ifa := range ifat {
83			switch ifa := ifa.(type) {
84			case *net.IPAddr:
85				if ip.Equal(ifa.IP) {
86					return &ifi, nil
87				}
88			case *net.IPNet:
89				if ip.Equal(ifa.IP) {
90					return &ifi, nil
91				}
92			}
93		}
94	}
95	return nil, errNoSuchInterface
96}
97
98func netInterfaceToIP4(ifi *net.Interface) (net.IP, error) {
99	if ifi == nil {
100		return net.IPv4zero.To4(), nil
101	}
102	ifat, err := ifi.Addrs()
103	if err != nil {
104		return nil, err
105	}
106	for _, ifa := range ifat {
107		switch ifa := ifa.(type) {
108		case *net.IPAddr:
109			if ip := ifa.IP.To4(); ip != nil {
110				return ip, nil
111			}
112		case *net.IPNet:
113			if ip := ifa.IP.To4(); ip != nil {
114				return ip, nil
115			}
116		}
117	}
118	return nil, errNoSuchInterface
119}
120