Example #1
0
// SerializeTo writes the serialized form of this layer into the
// SerializationBuffer, implementing gopacket.SerializableLayer.
// See the docs for gopacket.SerializableLayer for more info.
func (eth *Ethernet) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
	if len(eth.DstMAC) != 6 {
		return fmt.Errorf("invalid dst MAC: %v", eth.DstMAC)
	}
	if len(eth.SrcMAC) != 6 {
		return fmt.Errorf("invalid src MAC: %v", eth.SrcMAC)
	}
	payload := b.Bytes()
	bytes, err := b.PrependBytes(14)
	if err != nil {
		return err
	}
	copy(bytes, eth.DstMAC)
	copy(bytes[6:], eth.SrcMAC)
	if eth.Length != 0 || eth.EthernetType == EthernetTypeLLC {
		if opts.FixLengths {
			eth.Length = uint16(len(payload))
		}
		if eth.EthernetType != EthernetTypeLLC {
			return fmt.Errorf("ethernet type %v not compatible with length value %v", eth.EthernetType, eth.Length)
		} else if eth.Length > 0x0600 {
			return fmt.Errorf("invalid ethernet length %v", eth.Length)
		}
		binary.BigEndian.PutUint16(bytes[12:], eth.Length)
	} else {
		binary.BigEndian.PutUint16(bytes[12:], uint16(eth.EthernetType))
	}
	length := len(b.Bytes())
	if length < 60 {
		// Pad out to 60 bytes.
		padding, err := b.AppendBytes(60 - length)
		if err != nil {
			return err
		}
		copy(padding, lotsOfZeros[:])
	}
	return nil
}