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  //
    30  //	00:00:5e:00:53:01
    31  //	02:00:5e:10:00:00:00:01
    32  //	00:00:00:00:fe:80:00:00:00:00:00:00:02:00:5e:10:00:00:00:01
    33  //	00-00-5e-00-53-01
    34  //	02-00-5e-10-00-00-00-01
    35  //	00-00-00-00-fe-80-00-00-00-00-00-00-02-00-5e-10-00-00-00-01
    36  //	0000.5e00.5301
    37  //	0200.5e10.0000.0001
    38  //	0000.0000.fe80.0000.0000.0000.0200.5e10.0000.0001
    39  //	00005e005301
    40  func ParseMAC(s string) (hw HardwareAddr, err error) {
    41  	if len(s) < 12 {
    42  		goto error
    43  	}
    44  
    45  	if s[2] == ':' || s[2] == '-' {
    46  		if (len(s)+1)%3 != 0 {
    47  			goto error
    48  		}
    49  		n := (len(s) + 1) / 3
    50  		if n != 6 && n != 8 && n != 20 {
    51  			goto error
    52  		}
    53  		hw = make(HardwareAddr, n)
    54  		for x, i := 0, 0; i < n; i++ {
    55  			var ok bool
    56  			if hw[i], ok = xtoi2(s[x:], s[2]); !ok {
    57  				goto error
    58  			}
    59  			x += 3
    60  		}
    61  	} else if s[4] == '.' {
    62  		if (len(s)+1)%5 != 0 {
    63  			goto error
    64  		}
    65  		n := 2 * (len(s) + 1) / 5
    66  		if n != 6 && n != 8 && n != 20 {
    67  			goto error
    68  		}
    69  		hw = make(HardwareAddr, n)
    70  		for x, i := 0, 0; i < n; i += 2 {
    71  			var ok bool
    72  			if hw[i], ok = xtoi2(s[x:x+2], 0); !ok {
    73  				goto error
    74  			}
    75  			if hw[i+1], ok = xtoi2(s[x+2:], s[4]); !ok {
    76  				goto error
    77  			}
    78  			x += 5
    79  		}
    80  	} else {
    81  		if len(s)%2 != 0 {
    82  			goto error
    83  		}
    84  
    85  		n := len(s) / 2
    86  		if n != 6 && n != 8 && n != 20 {
    87  			goto error
    88  		}
    89  
    90  		hw = make(HardwareAddr, len(s)/2)
    91  		for x, i := 0, 0; i < n; i++ {
    92  			var ok bool
    93  			if hw[i], ok = xtoi2(s[x:x+2], 0); !ok {
    94  				goto error
    95  			}
    96  			x += 2
    97  		}
    98  	}
    99  	return hw, nil
   100  
   101  error:
   102  	return nil, &AddrError{Err: "invalid MAC address", Addr: s}
   103  }
   104
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