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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package header
import (
"encoding/binary"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
)
// ICMPv6 represents an ICMPv6 header stored in a byte array.
type ICMPv6 []byte
const (
// ICMPv6MinimumSize is the minimum size of a valid ICMP packet.
ICMPv6MinimumSize = 8
// ICMPv6PayloadOffset is the offset of the payload in an
// ICMP packet.
ICMPv6PayloadOffset = 8
// ICMPv6ProtocolNumber is the ICMP transport protocol number.
ICMPv6ProtocolNumber tcpip.TransportProtocolNumber = 58
// ICMPv6NeighborSolicitMinimumSize is the minimum size of a
// neighbor solicitation packet.
ICMPv6NeighborSolicitMinimumSize = ICMPv6MinimumSize + 16
// ICMPv6NeighborAdvertSize is size of a neighbor advertisement.
ICMPv6NeighborAdvertSize = 32
// ICMPv6EchoMinimumSize is the minimum size of a valid ICMP echo packet.
ICMPv6EchoMinimumSize = 8
// ICMPv6DstUnreachableMinimumSize is the minimum size of a valid ICMP
// destination unreachable packet.
ICMPv6DstUnreachableMinimumSize = ICMPv6MinimumSize
// ICMPv6PacketTooBigMinimumSize is the minimum size of a valid ICMP
// packet-too-big packet.
ICMPv6PacketTooBigMinimumSize = ICMPv6MinimumSize
// icmpv6ChecksumOffset is the offset of the checksum field
// in an ICMPv6 message.
icmpv6ChecksumOffset = 2
// icmpv6MTUOffset is the offset of the MTU field in an ICMPv6
// PacketTooBig message.
icmpv6MTUOffset = 4
// icmpv6IdentOffset is the offset of the ident field
// in a ICMPv6 Echo Request/Reply message.
icmpv6IdentOffset = 4
// icmpv6SequenceOffset is the offset of the sequence field
// in a ICMPv6 Echo Request/Reply message.
icmpv6SequenceOffset = 6
)
// ICMPv6Type is the ICMP type field described in RFC 4443 and friends.
type ICMPv6Type byte
// Typical values of ICMPv6Type defined in RFC 4443.
const (
ICMPv6DstUnreachable ICMPv6Type = 1
ICMPv6PacketTooBig ICMPv6Type = 2
ICMPv6TimeExceeded ICMPv6Type = 3
ICMPv6ParamProblem ICMPv6Type = 4
ICMPv6EchoRequest ICMPv6Type = 128
ICMPv6EchoReply ICMPv6Type = 129
// Neighbor Discovery Protocol (NDP) messages, see RFC 4861.
ICMPv6RouterSolicit ICMPv6Type = 133
ICMPv6RouterAdvert ICMPv6Type = 134
ICMPv6NeighborSolicit ICMPv6Type = 135
ICMPv6NeighborAdvert ICMPv6Type = 136
ICMPv6RedirectMsg ICMPv6Type = 137
)
// Values for ICMP code as defined in RFC 4443.
const (
ICMPv6PortUnreachable = 4
)
// Type is the ICMP type field.
func (b ICMPv6) Type() ICMPv6Type { return ICMPv6Type(b[0]) }
// SetType sets the ICMP type field.
func (b ICMPv6) SetType(t ICMPv6Type) { b[0] = byte(t) }
// Code is the ICMP code field. Its meaning depends on the value of Type.
func (b ICMPv6) Code() byte { return b[1] }
// SetCode sets the ICMP code field.
func (b ICMPv6) SetCode(c byte) { b[1] = c }
// Checksum is the ICMP checksum field.
func (b ICMPv6) Checksum() uint16 {
return binary.BigEndian.Uint16(b[icmpv6ChecksumOffset:])
}
// SetChecksum calculates and sets the ICMP checksum field.
func (b ICMPv6) SetChecksum(checksum uint16) {
binary.BigEndian.PutUint16(b[icmpv6ChecksumOffset:], checksum)
}
// SourcePort implements Transport.SourcePort.
func (ICMPv6) SourcePort() uint16 {
return 0
}
// DestinationPort implements Transport.DestinationPort.
func (ICMPv6) DestinationPort() uint16 {
return 0
}
// SetSourcePort implements Transport.SetSourcePort.
func (ICMPv6) SetSourcePort(uint16) {
}
// SetDestinationPort implements Transport.SetDestinationPort.
func (ICMPv6) SetDestinationPort(uint16) {
}
// MTU retrieves the MTU field from an ICMPv6 message.
func (b ICMPv6) MTU() uint32 {
return binary.BigEndian.Uint32(b[icmpv6MTUOffset:])
}
// SetMTU sets the MTU field from an ICMPv6 message.
func (b ICMPv6) SetMTU(mtu uint32) {
binary.BigEndian.PutUint32(b[icmpv6MTUOffset:], mtu)
}
// Ident retrieves the Ident field from an ICMPv6 message.
func (b ICMPv6) Ident() uint16 {
return binary.BigEndian.Uint16(b[icmpv6IdentOffset:])
}
// SetIdent sets the Ident field from an ICMPv6 message.
func (b ICMPv6) SetIdent(ident uint16) {
binary.BigEndian.PutUint16(b[icmpv6IdentOffset:], ident)
}
// Sequence retrieves the Sequence field from an ICMPv6 message.
func (b ICMPv6) Sequence() uint16 {
return binary.BigEndian.Uint16(b[icmpv6SequenceOffset:])
}
// SetSequence sets the Sequence field from an ICMPv6 message.
func (b ICMPv6) SetSequence(sequence uint16) {
binary.BigEndian.PutUint16(b[icmpv6SequenceOffset:], sequence)
}
// Payload implements Transport.Payload.
func (b ICMPv6) Payload() []byte {
return b[ICMPv6PayloadOffset:]
}
// ICMPv6Checksum calculates the ICMP checksum over the provided ICMP header,
// IPv6 src/dst addresses and the payload.
func ICMPv6Checksum(h ICMPv6, src, dst tcpip.Address, vv buffer.VectorisedView) uint16 {
// Calculate the IPv6 pseudo-header upper-layer checksum.
xsum := Checksum([]byte(src), 0)
xsum = Checksum([]byte(dst), xsum)
var upperLayerLength [4]byte
binary.BigEndian.PutUint32(upperLayerLength[:], uint32(len(h)+vv.Size()))
xsum = Checksum(upperLayerLength[:], xsum)
xsum = Checksum([]byte{0, 0, 0, uint8(ICMPv6ProtocolNumber)}, xsum)
for _, v := range vv.Views() {
xsum = Checksum(v, xsum)
}
// h[2:4] is the checksum itself, set it aside to avoid checksumming the checksum.
h2, h3 := h[2], h[3]
h[2], h[3] = 0, 0
xsum = ^Checksum(h, xsum)
h[2], h[3] = h2, h3
return xsum
}
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