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 package net
   6
   7 const hexDigit = "0123456789abcdef"
   8
   9 // A HardwareAddr represents a physical hardware address.
  10 type HardwareAddr []byte
  11
  12 func (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
  38 func 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
  83 error:
  84         return nil, &AddrError{Err: "invalid MAC address", Addr: s}
  85 }