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Source file src/net/mac.go

Documentation: net

  // Copyright 2011 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package net
  
  const hexDigit = "0123456789abcdef"
  
  // A HardwareAddr represents a physical hardware address.
  type HardwareAddr []byte
  
  func (a HardwareAddr) String() string {
  	if len(a) == 0 {
  		return ""
  	}
  	buf := make([]byte, 0, len(a)*3-1)
  	for i, b := range a {
  		if i > 0 {
  			buf = append(buf, ':')
  		}
  		buf = append(buf, hexDigit[b>>4])
  		buf = append(buf, hexDigit[b&0xF])
  	}
  	return string(buf)
  }
  
  // ParseMAC parses s as an IEEE 802 MAC-48, EUI-48, EUI-64, or a 20-octet
  // IP over InfiniBand link-layer address using one of the following formats:
  //   01:23:45:67:89:ab
  //   01:23:45:67:89:ab:cd:ef
  //   01:23:45:67:89:ab:cd:ef:00:00:01:23:45:67:89:ab:cd:ef:00:00
  //   01-23-45-67-89-ab
  //   01-23-45-67-89-ab-cd-ef
  //   01-23-45-67-89-ab-cd-ef-00-00-01-23-45-67-89-ab-cd-ef-00-00
  //   0123.4567.89ab
  //   0123.4567.89ab.cdef
  //   0123.4567.89ab.cdef.0000.0123.4567.89ab.cdef.0000
  func ParseMAC(s string) (hw HardwareAddr, err error) {
  	if len(s) < 14 {
  		goto error
  	}
  
  	if s[2] == ':' || s[2] == '-' {
  		if (len(s)+1)%3 != 0 {
  			goto error
  		}
  		n := (len(s) + 1) / 3
  		if n != 6 && n != 8 && n != 20 {
  			goto error
  		}
  		hw = make(HardwareAddr, n)
  		for x, i := 0, 0; i < n; i++ {
  			var ok bool
  			if hw[i], ok = xtoi2(s[x:], s[2]); !ok {
  				goto error
  			}
  			x += 3
  		}
  	} else if s[4] == '.' {
  		if (len(s)+1)%5 != 0 {
  			goto error
  		}
  		n := 2 * (len(s) + 1) / 5
  		if n != 6 && n != 8 && n != 20 {
  			goto error
  		}
  		hw = make(HardwareAddr, n)
  		for x, i := 0, 0; i < n; i += 2 {
  			var ok bool
  			if hw[i], ok = xtoi2(s[x:x+2], 0); !ok {
  				goto error
  			}
  			if hw[i+1], ok = xtoi2(s[x+2:], s[4]); !ok {
  				goto error
  			}
  			x += 5
  		}
  	} else {
  		goto error
  	}
  	return hw, nil
  
  error:
  	return nil, &AddrError{Err: "invalid MAC address", Addr: s}
  }
  

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