Source file src/pkg/net/mac.go
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 5 // MAC address manipulations 6 7 package net 8 9 import "errors" 10 11 const hexDigit = "0123456789abcdef" 12 13 // A HardwareAddr represents a physical hardware address. 14 type HardwareAddr []byte 15 16 func (a HardwareAddr) String() string { 17 if len(a) == 0 { 18 return "" 19 } 20 buf := make([]byte, 0, len(a)*3-1) 21 for i, b := range a { 22 if i > 0 { 23 buf = append(buf, ':') 24 } 25 buf = append(buf, hexDigit[b>>4]) 26 buf = append(buf, hexDigit[b&0xF]) 27 } 28 return string(buf) 29 } 30 31 // ParseMAC parses s as an IEEE 802 MAC-48, EUI-48, or EUI-64 using one of the 32 // following formats: 33 // 01:23:45:67:89:ab 34 // 01:23:45:67:89:ab:cd:ef 35 // 01-23-45-67-89-ab 36 // 01-23-45-67-89-ab-cd-ef 37 // 0123.4567.89ab 38 // 0123.4567.89ab.cdef 39 func 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 { 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 { 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 84 error: 85 return nil, errors.New("invalid MAC address: " + s) 86 }