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//   01:23:45:67:89:ab
30//   01:23:45:67:89:ab:cd:ef
31//   01:23:45:67:89:ab:cd:ef:00:00:01:23:45:67:89:ab:cd:ef:00:00
32//   01-23-45-67-89-ab
33//   01-23-45-67-89-ab-cd-ef
34//   01-23-45-67-89-ab-cd-ef-00-00-01-23-45-67-89-ab-cd-ef-00-00
35//   0123.4567.89ab
36//   0123.4567.89ab.cdef
37//   0123.4567.89ab.cdef.0000.0123.4567.89ab.cdef.0000
38func ParseMAC(s string) (hw HardwareAddr, err error) {
39	if len(s) < 14 {
40		goto error
41	}
42
43	if s[2] == ':' || s[2] == '-' {
44		if (len(s)+1)%3 != 0 {
45			goto error
46		}
47		n := (len(s) + 1) / 3
48		if n != 6 && n != 8 && n != 20 {
49			goto error
50		}
51		hw = make(HardwareAddr, n)
52		for x, i := 0, 0; i < n; i++ {
53			var ok bool
54			if hw[i], ok = xtoi2(s[x:], s[2]); !ok {
55				goto error
56			}
57			x += 3
58		}
59	} else if s[4] == '.' {
60		if (len(s)+1)%5 != 0 {
61			goto error
62		}
63		n := 2 * (len(s) + 1) / 5
64		if n != 6 && n != 8 && n != 20 {
65			goto error
66		}
67		hw = make(HardwareAddr, n)
68		for x, i := 0, 0; i < n; i += 2 {
69			var ok bool
70			if hw[i], ok = xtoi2(s[x:x+2], 0); !ok {
71				goto error
72			}
73			if hw[i+1], ok = xtoi2(s[x+2:], s[4]); !ok {
74				goto error
75			}
76			x += 5
77		}
78	} else {
79		goto error
80	}
81	return hw, nil
82
83error:
84	return nil, &AddrError{Err: "invalid MAC address", Addr: s}
85}
86