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, or EUI-64 using one of the
28// 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
32//   01-23-45-67-89-ab-cd-ef
33//   0123.4567.89ab
34//   0123.4567.89ab.cdef
35func ParseMAC(s string) (hw HardwareAddr, err error) {
36	if len(s) < 14 {
37		goto error
38	}
39
40	if s[2] == ':' || s[2] == '-' {
41		if (len(s)+1)%3 != 0 {
42			goto error
43		}
44		n := (len(s) + 1) / 3
45		if n != 6 && n != 8 {
46			goto error
47		}
48		hw = make(HardwareAddr, n)
49		for x, i := 0, 0; i < n; i++ {
50			var ok bool
51			if hw[i], ok = xtoi2(s[x:], s[2]); !ok {
52				goto error
53			}
54			x += 3
55		}
56	} else if s[4] == '.' {
57		if (len(s)+1)%5 != 0 {
58			goto error
59		}
60		n := 2 * (len(s) + 1) / 5
61		if n != 6 && n != 8 {
62			goto error
63		}
64		hw = make(HardwareAddr, n)
65		for x, i := 0, 0; i < n; i += 2 {
66			var ok bool
67			if hw[i], ok = xtoi2(s[x:x+2], 0); !ok {
68				goto error
69			}
70			if hw[i+1], ok = xtoi2(s[x+2:], s[4]); !ok {
71				goto error
72			}
73			x += 5
74		}
75	} else {
76		goto error
77	}
78	return hw, nil
79
80error:
81	return nil, &AddrError{Err: "invalid MAC address", Addr: s}
82}
83