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
7const hexDigit = "0123456789abcdef"
8
9// A HardwareAddr represents a physical hardware address.
10type HardwareAddr []byte
11
12func (a HardwareAddr) String() string {
13	if len(a) == 0 {
14		return ""
15	}
16	buf := make([]byte, 0, len(a)*3-1)
17	for i, b := range a {
18		if i > 0 {
19			buf = append(buf, ':')
20		}
21		buf = append(buf, hexDigit[b>>4])
22		buf = append(buf, hexDigit[b&0xF])
23	}
24	return string(buf)
25}
26
27// ParseMAC parses s as an IEEE 802 MAC-48, EUI-48, EUI-64, or a 20-octet
28// IP over InfiniBand link-layer address using one of the following formats:
29//
30//	00:00:5e:00:53:01
31//	02:00:5e:10:00:00:00:01
32//	00:00:00:00:fe:80:00:00:00:00:00:00:02:00:5e:10:00:00:00:01
33//	00-00-5e-00-53-01
34//	02-00-5e-10-00-00-00-01
35//	00-00-00-00-fe-80-00-00-00-00-00-00-02-00-5e-10-00-00-00-01
36//	0000.5e00.5301
37//	0200.5e10.0000.0001
38//	0000.0000.fe80.0000.0000.0000.0200.5e10.0000.0001
39func ParseMAC(s string) (hw HardwareAddr, err error) {
40	if len(s) < 14 {
41		goto error
42	}
43
44	if s[2] == ':' || s[2] == '-' {
45		if (len(s)+1)%3 != 0 {
46			goto error
47		}
48		n := (len(s) + 1) / 3
49		if n != 6 && n != 8 && n != 20 {
50			goto error
51		}
52		hw = make(HardwareAddr, n)
53		for x, i := 0, 0; i < n; i++ {
54			var ok bool
55			if hw[i], ok = xtoi2(s[x:], s[2]); !ok {
56				goto error
57			}
58			x += 3
59		}
60	} else if s[4] == '.' {
61		if (len(s)+1)%5 != 0 {
62			goto error
63		}
64		n := 2 * (len(s) + 1) / 5
65		if n != 6 && n != 8 && n != 20 {
66			goto error
67		}
68		hw = make(HardwareAddr, n)
69		for x, i := 0, 0; i < n; i += 2 {
70			var ok bool
71			if hw[i], ok = xtoi2(s[x:x+2], 0); !ok {
72				goto error
73			}
74			if hw[i+1], ok = xtoi2(s[x+2:], s[4]); !ok {
75				goto error
76			}
77			x += 5
78		}
79	} else {
80		goto error
81	}
82	return hw, nil
83
84error:
85	return nil, &AddrError{Err: "invalid MAC address", Addr: s}
86}
87