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- package layers
- import (
- "encoding/binary"
- "fmt"
- "github.com/google/gopacket"
- )
- type Dot1Q struct {
- BaseLayer
- Priority uint8
- DropEligible bool
- VLANIdentifier uint16
- Type EthernetType
- }
- func (d *Dot1Q) LayerType() gopacket.LayerType { return LayerTypeDot1Q }
- func (d *Dot1Q) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
- d.Priority = (data[0] & 0xE0) >> 5
- d.DropEligible = data[0]&0x10 != 0
- d.VLANIdentifier = binary.BigEndian.Uint16(data[:2]) & 0x0FFF
- d.Type = EthernetType(binary.BigEndian.Uint16(data[2:4]))
- d.BaseLayer = BaseLayer{Contents: data[:4], Payload: data[4:]}
- return nil
- }
- func (d *Dot1Q) CanDecode() gopacket.LayerClass {
- return LayerTypeDot1Q
- }
- func (d *Dot1Q) NextLayerType() gopacket.LayerType {
- return d.Type.LayerType()
- }
- func decodeDot1Q(data []byte, p gopacket.PacketBuilder) error {
- d := &Dot1Q{}
- return decodingLayerDecoder(d, data, p)
- }
- func (d *Dot1Q) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
- bytes, err := b.PrependBytes(4)
- if err != nil {
- return err
- }
- if d.VLANIdentifier > 0xFFF {
- return fmt.Errorf("vlan identifier %v is too high", d.VLANIdentifier)
- }
- firstBytes := uint16(d.Priority)<<13 | d.VLANIdentifier
- if d.DropEligible {
- firstBytes |= 0x1000
- }
- binary.BigEndian.PutUint16(bytes, firstBytes)
- binary.BigEndian.PutUint16(bytes[2:], uint16(d.Type))
- return nil
- }
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