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  //	00:00:5e:00:53:01
		30  //	02:00:5e:10:00:00:00:01
		31  //	00:00:00:00:fe:80:00:00:00:00:00:00:02:00:5e:10:00:00:00:01
		32  //	00-00-5e-00-53-01
		33  //	02-00-5e-10-00-00-00-01
		34  //	00-00-00-00-fe-80-00-00-00-00-00-00-02-00-5e-10-00-00-00-01
		35  //	0000.5e00.5301
		36  //	0200.5e10.0000.0001
		37  //	0000.0000.fe80.0000.0000.0000.0200.5e10.0000.0001
		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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