libgo/go/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 }