eruhs/core/parser/ethernet.go

package parser

import (
    "encoding/binary"
    "errors"
    "net"
)

// 取值参考自https://en.wikipedia.org/wiki/EtherType，只取常用的ipv4/6和arp类型
const (
    EthernetTypeIPv4 = 0x0800
    EthernetTypeARP  = 0x0806
    EthernetTypeIPv6 = 0x86DD
)

type Ethernet struct {
    BaseLayer
    Source      net.HardwareAddr // 源mac
    Destination net.HardwareAddr // 目的mac
    Type        uint16           // 网络层协议类型
}

func (e *Ethernet) LayerType() int {
    return LayerTypeEthernet
}

func (e *Ethernet) GetSourceMac() string {
    return e.Source.String()
}

func (e *Ethernet) GetDestinationMac() string {
    return e.Destination.String()
}

func DecodeEthernet(data []byte) (*Ethernet, error) {
    // 帧数据大小小于14，不符合以太网帧格式要求
    if len(data) < 14 {
        return nil, errors.New("[ethernet] 数据包太小，不符合以太网帧格式要求")
    }

    eth := &Ethernet{}
    eth.Destination = data[:6]                      // 0~5 byte: 目标mac
    eth.Source = data[6:12]                         // 6~11 byte: 源mac
    eth.Type = binary.BigEndian.Uint16(data[12:14]) // 12~13 byte: 类型字段，大端序，uint16

    eth.Header = data[:14]
    eth.Payload = data[14:]
    return eth, nil
}