1 files changed, 191 insertions, 0 deletions
diff --git a/pkg/tcpip/header/ipv6.go b/pkg/tcpip/header/ipv6.go
new file mode 100644
index 000000000..d8dc138b3
--- /dev/null
+++ b/pkg/tcpip/header/ipv6.go
@@ -0,0 +1,191 @@
+// Copyright 2016 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 (
+	versTCFL   = 0
+	payloadLen = 4
+	nextHdr    = 6
+	hopLimit   = 7
+	v6SrcAddr  = 8
+	v6DstAddr  = 24
+)
+
+// IPv6Fields contains the fields of an IPv6 packet. It is used to describe the
+// fields of a packet that needs to be encoded.
+type IPv6Fields struct {
+	// TrafficClass is the "traffic class" field of an IPv6 packet.
+	TrafficClass uint8
+
+	// FlowLabel is the "flow label" field of an IPv6 packet.
+	FlowLabel uint32
+
+	// PayloadLength is the "payload length" field of an IPv6 packet.
+	PayloadLength uint16
+
+	// NextHeader is the "next header" field of an IPv6 packet.
+	NextHeader uint8
+
+	// HopLimit is the "hop limit" field of an IPv6 packet.
+	HopLimit uint8
+
+	// SrcAddr is the "source ip address" of an IPv6 packet.
+	SrcAddr tcpip.Address
+
+	// DstAddr is the "destination ip address" of an IPv6 packet.
+	DstAddr tcpip.Address
+}
+
+// IPv6 represents an ipv6 header stored in a byte array.
+// Most of the methods of IPv6 access to the underlying slice without
+// checking the boundaries and could panic because of 'index out of range'.
+// Always call IsValid() to validate an instance of IPv6 before using other methods.
+type IPv6 []byte
+
+const (
+	// IPv6MinimumSize is the minimum size of a valid IPv6 packet.
+	IPv6MinimumSize = 40
+
+	// IPv6AddressSize is the size, in bytes, of an IPv6 address.
+	IPv6AddressSize = 16
+
+	// IPv6ProtocolNumber is IPv6's network protocol number.
+	IPv6ProtocolNumber tcpip.NetworkProtocolNumber = 0x86dd
+
+	// IPv6Version is the version of the ipv6 procotol.
+	IPv6Version = 6
+
+	// IPv6MinimumMTU is the minimum MTU required by IPv6, per RFC 2460,
+	// section 5.
+	IPv6MinimumMTU = 1280
+)
+
+// PayloadLength returns the value of the "payload length" field of the ipv6
+// header.
+func (b IPv6) PayloadLength() uint16 {
+	return binary.BigEndian.Uint16(b[payloadLen:])
+}
+
+// HopLimit returns the value of the "hop limit" field of the ipv6 header.
+func (b IPv6) HopLimit() uint8 {
+	return b[hopLimit]
+}
+
+// NextHeader returns the value of the "next header" field of the ipv6 header.
+func (b IPv6) NextHeader() uint8 {
+	return b[nextHdr]
+}
+
+// TransportProtocol implements Network.TransportProtocol.
+func (b IPv6) TransportProtocol() tcpip.TransportProtocolNumber {
+	return tcpip.TransportProtocolNumber(b.NextHeader())
+}
+
+// Payload implements Network.Payload.
+func (b IPv6) Payload() []byte {
+	return b[IPv6MinimumSize:][:b.PayloadLength()]
+}
+
+// SourceAddress returns the "source address" field of the ipv6 header.
+func (b IPv6) SourceAddress() tcpip.Address {
+	return tcpip.Address(b[v6SrcAddr : v6SrcAddr+IPv6AddressSize])
+}
+
+// DestinationAddress returns the "destination address" field of the ipv6
+// header.
+func (b IPv6) DestinationAddress() tcpip.Address {
+	return tcpip.Address(b[v6DstAddr : v6DstAddr+IPv6AddressSize])
+}
+
+// Checksum implements Network.Checksum. Given that IPv6 doesn't have a
+// checksum, it just returns 0.
+func (IPv6) Checksum() uint16 {
+	return 0
+}
+
+// TOS returns the "traffic class" and "flow label" fields of the ipv6 header.
+func (b IPv6) TOS() (uint8, uint32) {
+	v := binary.BigEndian.Uint32(b[versTCFL:])
+	return uint8(v >> 20), v & 0xfffff
+}
+
+// SetTOS sets the "traffic class" and "flow label" fields of the ipv6 header.
+func (b IPv6) SetTOS(t uint8, l uint32) {
+	vtf := (6 << 28) | (uint32(t) << 20) | (l & 0xfffff)
+	binary.BigEndian.PutUint32(b[versTCFL:], vtf)
+}
+
+// SetPayloadLength sets the "payload length" field of the ipv6 header.
+func (b IPv6) SetPayloadLength(payloadLength uint16) {
+	binary.BigEndian.PutUint16(b[payloadLen:], payloadLength)
+}
+
+// SetSourceAddress sets the "source address" field of the ipv6 header.
+func (b IPv6) SetSourceAddress(addr tcpip.Address) {
+	copy(b[v6SrcAddr:v6SrcAddr+IPv6AddressSize], addr)
+}
+
+// SetDestinationAddress sets the "destination address" field of the ipv6
+// header.
+func (b IPv6) SetDestinationAddress(addr tcpip.Address) {
+	copy(b[v6DstAddr:v6DstAddr+IPv6AddressSize], addr)
+}
+
+// SetNextHeader sets the value of the "next header" field of the ipv6 header.
+func (b IPv6) SetNextHeader(v uint8) {
+	b[nextHdr] = v
+}
+
+// SetChecksum implements Network.SetChecksum. Given that IPv6 doesn't have a
+// checksum, it is empty.
+func (IPv6) SetChecksum(uint16) {
+}
+
+// Encode encodes all the fields of the ipv6 header.
+func (b IPv6) Encode(i *IPv6Fields) {
+	b.SetTOS(i.TrafficClass, i.FlowLabel)
+	b.SetPayloadLength(i.PayloadLength)
+	b[nextHdr] = i.NextHeader
+	b[hopLimit] = i.HopLimit
+	copy(b[v6SrcAddr:v6SrcAddr+IPv6AddressSize], i.SrcAddr)
+	copy(b[v6DstAddr:v6DstAddr+IPv6AddressSize], i.DstAddr)
+}
+
+// IsValid performs basic validation on the packet.
+func (b IPv6) IsValid(pktSize int) bool {
+	if len(b) < IPv6MinimumSize {
+		return false
+	}
+
+	dlen := int(b.PayloadLength())
+	if dlen > pktSize-IPv6MinimumSize {
+		return false
+	}
+
+	return true
+}
+
+// IsV4MappedAddress determines if the provided address is an IPv4 mapped
+// address by checking if its prefix is 0:0:0:0:0:ffff::/96.
+func IsV4MappedAddress(addr tcpip.Address) bool {
+	if len(addr) != IPv6AddressSize {
+		return false
+	}
+
+	const prefix = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff"
+	for i := 0; i < len(prefix); i++ {
+		if prefix[i] != addr[i] {
+			return false
+		}
+	}
+
+	return true
+}