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115 lines (94 loc) · 3.55 KB
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// Copyright (c) 2013, Benjamin J. Kelly ("Author")
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/**
* @author https://github.com/wanderview
*/
import MAC from './mac'
const TYPE_TO_STRING = {
0x0800: 'ip',
0x0806: 'arp'
}
const TYPE_FROM_STRING = {
ip: 0x0800,
arp: 0x0806
}
export default class Ethernet {
constructor(option){
if (option instanceof Buffer)
return Ethernet.fromBuffer(option)
option = option || {}
this.src = option.src || MAC.empty
this.dst = option.dst || MAC.full
if (option.type) {
this.type = option.type
this.typeCode = TYPE_FROM_STRING[this.type]
} else if (option.typeCode) {
this.typeCode = option.typeCode
this.type = TYPE_TO_STRING[this.typeCode]
} else {
this.type = 'ip'
this.typeCode = TYPE_FROM_STRING[this.type]
}
if (typeof this.typeCode !== 'number')
throw(new Error('Unsupported type [' + this.type + ']'))
this.length = option.length || 14
if (this.length !== 14) {
throw new Error(
'Unsupported ethernet frame length [' + this.length +
']; must be 14 as only most common cases are implemented.')
}
return this
}
fromBuffer(buffer, offset) {
offset = ~~offset
let length = 0
let dst = MAC.toString(buffer, offset + length)
length += MAC.length
let src = MAC.toString(buffer, offset + length)
length += MAC.length
let typeCode = buffer.readUInt16BE(offset + length)
length += 2
let type = TYPE_TO_STRING[typeCode]
if (!type)
throw(new Error('Unsupported type code [' + typeCode + ']'))
return new Ethernet({
dst,
src,
type,
typeCode,
length
})
}
toBuffer(buffer, offset) {
offset = ~~offset
buffer = (buffer instanceof Buffer) ?
buffer : Buffer.alloc(offset + this.length)
MAC.toBuffer(this.dst, buffer, offset)
offset += MAC.length
MAC.toBuffer(this.src, buffer, offset)
offset += MAC.length
buffer.writeUInt16BE(this.typeCode, offset)
offset += 2
return buffer
}
}