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Source file src/net/mac.go

Documentation: net

     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  }
    86  

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