65 lines
1.9 KiB
Go
65 lines
1.9 KiB
Go
|
// Copyright 2017 The Netstack Authors. All rights reserved.
|
||
|
// Use of this source code is governed by a BSD-style
|
||
|
// license that can be found in the LICENSE file.
|
||
|
|
||
|
package header
|
||
|
|
||
|
import (
|
||
|
"encoding/binary"
|
||
|
|
||
|
"gvisor.googlesource.com/gvisor/pkg/tcpip"
|
||
|
)
|
||
|
|
||
|
const (
|
||
|
dstMAC = 0
|
||
|
srcMAC = 6
|
||
|
ethType = 12
|
||
|
)
|
||
|
|
||
|
// EthernetFields contains the fields of an ethernet frame header. It is used to
|
||
|
// describe the fields of a frame that needs to be encoded.
|
||
|
type EthernetFields struct {
|
||
|
// SrcAddr is the "MAC source" field of an ethernet frame header.
|
||
|
SrcAddr tcpip.LinkAddress
|
||
|
|
||
|
// DstAddr is the "MAC destination" field of an ethernet frame header.
|
||
|
DstAddr tcpip.LinkAddress
|
||
|
|
||
|
// Type is the "ethertype" field of an ethernet frame header.
|
||
|
Type tcpip.NetworkProtocolNumber
|
||
|
}
|
||
|
|
||
|
// Ethernet represents an ethernet frame header stored in a byte array.
|
||
|
type Ethernet []byte
|
||
|
|
||
|
const (
|
||
|
// EthernetMinimumSize is the minimum size of a valid ethernet frame.
|
||
|
EthernetMinimumSize = 14
|
||
|
|
||
|
// EthernetAddressSize is the size, in bytes, of an ethernet address.
|
||
|
EthernetAddressSize = 6
|
||
|
)
|
||
|
|
||
|
// SourceAddress returns the "MAC source" field of the ethernet frame header.
|
||
|
func (b Ethernet) SourceAddress() tcpip.LinkAddress {
|
||
|
return tcpip.LinkAddress(b[srcMAC:][:EthernetAddressSize])
|
||
|
}
|
||
|
|
||
|
// DestinationAddress returns the "MAC destination" field of the ethernet frame
|
||
|
// header.
|
||
|
func (b Ethernet) DestinationAddress() tcpip.LinkAddress {
|
||
|
return tcpip.LinkAddress(b[dstMAC:][:EthernetAddressSize])
|
||
|
}
|
||
|
|
||
|
// Type returns the "ethertype" field of the ethernet frame header.
|
||
|
func (b Ethernet) Type() tcpip.NetworkProtocolNumber {
|
||
|
return tcpip.NetworkProtocolNumber(binary.BigEndian.Uint16(b[ethType:]))
|
||
|
}
|
||
|
|
||
|
// Encode encodes all the fields of the ethernet frame header.
|
||
|
func (b Ethernet) Encode(e *EthernetFields) {
|
||
|
binary.BigEndian.PutUint16(b[ethType:], uint16(e.Type))
|
||
|
copy(b[srcMAC:][:EthernetAddressSize], e.SrcAddr)
|
||
|
copy(b[dstMAC:][:EthernetAddressSize], e.DstAddr)
|
||
|
}
|