Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 64 insertions, 0 deletions

diff --git a/pkg/tcpip/header/eth.go b/pkg/tcpip/header/eth.go
new file mode 100644
index 000000000..23b7efdfc
--- /dev/null
+++ b/pkg/tcpip/header/eth.go
@@ -0,0 +1,64 @@
+// 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)
+}