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layers.go
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layers.go
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// Copyright 2020 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 testbench
import (
"encoding/binary"
"encoding/hex"
"fmt"
"net"
"reflect"
"strings"
"github.com/google/go-cmp/cmp"
"github.com/google/go-cmp/cmp/cmpopts"
"go.uber.org/multierr"
"gvisor.dev/gvisor/pkg/buffer"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/checksum"
"gvisor.dev/gvisor/pkg/tcpip/header"
)
// Layer is the interface that all encapsulations must implement.
//
// A Layer is an encapsulation in a packet, such as TCP, IPv4, IPv6, etc. A
// Layer contains all the fields of the encapsulation. Each field is a pointer
// and may be nil.
type Layer interface {
fmt.Stringer
// ToBytes converts the Layer into bytes. In places where the Layer's field
// isn't nil, the value that is pointed to is used. When the field is nil, a
// reasonable default for the Layer is used. For example, "64" for IPv4 TTL
// and a calculated checksum for TCP or IP. Some layers require information
// from the previous or next layers in order to compute a default, such as
// TCP's checksum or Ethernet's type, so each Layer has a doubly-linked list
// to the layer's neighbors.
ToBytes() ([]byte, error)
// match checks if the current Layer matches the provided Layer. If either
// Layer has a nil in a given field, that field is considered matching.
// Otherwise, the values pointed to by the fields must match. The LayerBase is
// ignored.
match(Layer) bool
// length in bytes of the current encapsulation
length() int
// next gets a pointer to the encapsulated Layer.
next() Layer
// prev gets a pointer to the Layer encapsulating this one.
Prev() Layer
// setNext sets the pointer to the encapsulated Layer.
setNext(Layer)
// setPrev sets the pointer to the Layer encapsulating this one.
setPrev(Layer)
// merge overrides the values in the interface with the provided values.
merge(Layer) error
}
// LayerBase is the common elements of all layers.
type LayerBase struct {
nextLayer Layer
prevLayer Layer
}
func (lb *LayerBase) next() Layer {
return lb.nextLayer
}
// Prev returns the previous layer.
func (lb *LayerBase) Prev() Layer {
return lb.prevLayer
}
func (lb *LayerBase) setNext(l Layer) {
lb.nextLayer = l
}
func (lb *LayerBase) setPrev(l Layer) {
lb.prevLayer = l
}
// equalLayer compares that two Layer structs match while ignoring field in
// which either input has a nil and also ignoring the LayerBase of the inputs.
func equalLayer(x, y Layer) bool {
if x == nil || y == nil {
return true
}
// opt ignores comparison pairs where either of the inputs is a nil.
opt := cmp.FilterValues(func(x, y any) bool {
for _, l := range []any{x, y} {
v := reflect.ValueOf(l)
if (v.Kind() == reflect.Ptr || v.Kind() == reflect.Slice) && v.IsNil() {
return true
}
}
return false
}, cmp.Ignore())
return cmp.Equal(x, y, opt, cmpopts.IgnoreTypes(LayerBase{}))
}
// mergeLayer merges y into x. Any fields for which y has a non-nil value, that
// value overwrite the corresponding fields in x.
func mergeLayer(x, y Layer) error {
if y == nil {
return nil
}
if reflect.TypeOf(x) != reflect.TypeOf(y) {
return fmt.Errorf("can't merge %T into %T", y, x)
}
vx := reflect.ValueOf(x).Elem()
vy := reflect.ValueOf(y).Elem()
t := vy.Type()
for i := 0; i < vy.NumField(); i++ {
t := t.Field(i)
if t.Anonymous {
// Ignore the LayerBase in the Layer struct.
continue
}
v := vy.Field(i)
if v.IsNil() {
continue
}
vx.Field(i).Set(v)
}
return nil
}
func stringLayer(l Layer) string {
v := reflect.ValueOf(l).Elem()
t := v.Type()
var ret []string
for i := 0; i < v.NumField(); i++ {
t := t.Field(i)
if t.Anonymous {
// Ignore the LayerBase in the Layer struct.
continue
}
v := v.Field(i)
if v.IsNil() {
continue
}
v = reflect.Indirect(v)
switch {
// Try to use Stringers appropriately.
case v.Type().Implements(reflect.TypeOf((*fmt.Stringer)(nil)).Elem()):
ret = append(ret, fmt.Sprintf("%s:%v", t.Name, v))
// Print byte slices as hex.
case v.Kind() == reflect.Slice && v.Type().Elem().Kind() == reflect.Uint8:
ret = append(ret, fmt.Sprintf("%s:\n%v", t.Name, hex.Dump(v.Bytes())))
// Otherwise just let Go decide how to print.
default:
ret = append(ret, fmt.Sprintf("%s:%v", t.Name, v))
}
}
return fmt.Sprintf("&%s{%s}", t, strings.Join(ret, " "))
}
// Ether can construct and match an ethernet encapsulation.
type Ether struct {
LayerBase
SrcAddr *tcpip.LinkAddress
DstAddr *tcpip.LinkAddress
Type *tcpip.NetworkProtocolNumber
}
func (l *Ether) String() string {
return stringLayer(l)
}
// ToBytes implements Layer.ToBytes.
func (l *Ether) ToBytes() ([]byte, error) {
b := make([]byte, header.EthernetMinimumSize)
h := header.Ethernet(b)
fields := &header.EthernetFields{}
if l.SrcAddr != nil {
fields.SrcAddr = *l.SrcAddr
}
if l.DstAddr != nil {
fields.DstAddr = *l.DstAddr
}
if l.Type != nil {
fields.Type = *l.Type
} else {
switch n := l.next().(type) {
case *IPv4:
fields.Type = header.IPv4ProtocolNumber
case *IPv6:
fields.Type = header.IPv6ProtocolNumber
default:
return nil, fmt.Errorf("ethernet header's next layer is unrecognized: %#v", n)
}
}
h.Encode(fields)
return h, nil
}
// LinkAddress is a helper routine that allocates a new tcpip.LinkAddress value
// to store v and returns a pointer to it.
func LinkAddress(v tcpip.LinkAddress) *tcpip.LinkAddress {
return &v
}
// NetworkProtocolNumber is a helper routine that allocates a new
// tcpip.NetworkProtocolNumber value to store v and returns a pointer to it.
func NetworkProtocolNumber(v tcpip.NetworkProtocolNumber) *tcpip.NetworkProtocolNumber {
return &v
}
// bodySizeHint describes num of bytes left to parse for the rest of layers.
type bodySizeHint int
const bodySizeUnknown bodySizeHint = -1
// layerParser parses the input bytes and returns a Layer along with the next
// layerParser to run. If there is no more parsing to do, the returned
// layerParser is nil.
type layerParser func([]byte) (Layer, bodySizeHint, layerParser)
// parse parses bytes starting with the first layerParser and using successive
// layerParsers until all the bytes are parsed.
func parse(parser layerParser, b []byte) Layers {
var layers Layers
for {
layer, hint, next := parser(b)
layers = append(layers, layer)
if parser == nil {
break
}
b = b[layer.length():]
if hint != bodySizeUnknown {
b = b[:hint]
}
if next == nil {
break
}
parser = next
}
layers.linkLayers()
return layers
}
// parseEther parses the bytes assuming that they start with an ethernet header
// and continues parsing further encapsulations.
func parseEther(b []byte) (Layer, bodySizeHint, layerParser) {
h := header.Ethernet(b)
ether := Ether{
SrcAddr: LinkAddress(h.SourceAddress()),
DstAddr: LinkAddress(h.DestinationAddress()),
Type: NetworkProtocolNumber(h.Type()),
}
var nextParser layerParser
switch h.Type() {
case header.IPv4ProtocolNumber:
nextParser = parseIPv4
case header.IPv6ProtocolNumber:
nextParser = parseIPv6
default:
// Assume that the rest is a payload.
nextParser = parsePayload
}
return ðer, bodySizeUnknown, nextParser
}
func (l *Ether) match(other Layer) bool {
return equalLayer(l, other)
}
func (l *Ether) length() int {
return header.EthernetMinimumSize
}
// merge implements Layer.merge.
func (l *Ether) merge(other Layer) error {
return mergeLayer(l, other)
}
// IPv4 can construct and match an IPv4 encapsulation.
type IPv4 struct {
LayerBase
IHL *uint8
TOS *uint8
TotalLength *uint16
ID *uint16
Flags *uint8
FragmentOffset *uint16
TTL *uint8
Protocol *uint8
Checksum *uint16
SrcAddr *net.IP
DstAddr *net.IP
Options *header.IPv4Options
}
func (l *IPv4) String() string {
return stringLayer(l)
}
// ToBytes implements Layer.ToBytes.
func (l *IPv4) ToBytes() ([]byte, error) {
// An IPv4 header is variable length depending on the size of the Options.
hdrLen := header.IPv4MinimumSize
if l.Options != nil {
if len(*l.Options)%4 != 0 {
return nil, fmt.Errorf("invalid header options '%x (len=%d)'; must be 32 bit aligned", *l.Options, len(*l.Options))
}
hdrLen += len(*l.Options)
if hdrLen > header.IPv4MaximumHeaderSize {
return nil, fmt.Errorf("IPv4 Options %d bytes, Max %d", len(*l.Options), header.IPv4MaximumOptionsSize)
}
}
b := make([]byte, hdrLen)
h := header.IPv4(b)
fields := &header.IPv4Fields{
TOS: 0,
TotalLength: 0,
ID: 0,
Flags: 0,
FragmentOffset: 0,
TTL: 64,
Protocol: 0,
Checksum: 0,
SrcAddr: tcpip.Address{},
DstAddr: tcpip.Address{},
Options: nil,
}
if l.TOS != nil {
fields.TOS = *l.TOS
}
if l.TotalLength != nil {
fields.TotalLength = *l.TotalLength
} else {
fields.TotalLength = uint16(l.length())
current := l.next()
for current != nil {
fields.TotalLength += uint16(current.length())
current = current.next()
}
}
if l.ID != nil {
fields.ID = *l.ID
}
if l.Flags != nil {
fields.Flags = *l.Flags
}
if l.FragmentOffset != nil {
fields.FragmentOffset = *l.FragmentOffset
}
if l.TTL != nil {
fields.TTL = *l.TTL
}
if l.Protocol != nil {
fields.Protocol = *l.Protocol
} else {
switch n := l.next().(type) {
case *TCP:
fields.Protocol = uint8(header.TCPProtocolNumber)
case *UDP:
fields.Protocol = uint8(header.UDPProtocolNumber)
case *ICMPv4:
fields.Protocol = uint8(header.ICMPv4ProtocolNumber)
default:
// We can add support for more protocols as needed.
return nil, fmt.Errorf("ipv4 header's next layer is unrecognized: %#v", n)
}
}
if l.SrcAddr != nil && len(*l.SrcAddr) > 0 {
fields.SrcAddr = tcpip.AddrFrom4Slice(*l.SrcAddr)
}
if l.DstAddr != nil && len(*l.DstAddr) > 0 {
fields.DstAddr = tcpip.AddrFrom4Slice(*l.DstAddr)
}
h.Encode(fields)
// Put raw option bytes from test definition in header. Options as raw bytes
// allows us to serialize malformed options, which is not possible with
// the provided serialization functions.
if l.Options != nil {
h.SetHeaderLength(h.HeaderLength() + uint8(len(*l.Options)))
if got, want := copy(h.Options(), *l.Options), len(*l.Options); got != want {
return nil, fmt.Errorf("failed to copy option bytes into header, got %d want %d", got, want)
}
}
// Encode cannot set this incorrectly so we need to overwrite what it wrote
// in order to test handling of a bad IHL value.
if l.IHL != nil {
h.SetHeaderLength(*l.IHL)
}
if l.Checksum == nil {
h.SetChecksum(^h.CalculateChecksum())
} else {
h.SetChecksum(*l.Checksum)
}
return h, nil
}
// Uint16 is a helper routine that allocates a new
// uint16 value to store v and returns a pointer to it.
func Uint16(v uint16) *uint16 {
return &v
}
// Uint8 is a helper routine that allocates a new
// uint8 value to store v and returns a pointer to it.
func Uint8(v uint8) *uint8 {
return &v
}
// TCPFlags is a helper routine that allocates a new
// header.TCPFlags value to store v and returns a pointer to it.
func TCPFlags(v header.TCPFlags) *header.TCPFlags {
return &v
}
// Address is a helper routine that allocates a new net.IP value to
// store v and returns a pointer to it.
func Address(v tcpip.Address) *net.IP {
bs := make([]byte, v.Len())
copy(bs, v.AsSlice())
ret := net.IP(bs)
return &ret
}
// parseIPv4 parses the bytes assuming that they start with an ipv4 header and
// continues parsing further encapsulations.
func parseIPv4(b []byte) (Layer, bodySizeHint, layerParser) {
h := header.IPv4(b)
options := h.Options()
tos, _ := h.TOS()
ipv4 := IPv4{
IHL: Uint8(h.HeaderLength()),
TOS: &tos,
TotalLength: Uint16(h.TotalLength()),
ID: Uint16(h.ID()),
Flags: Uint8(h.Flags()),
FragmentOffset: Uint16(h.FragmentOffset()),
TTL: Uint8(h.TTL()),
Protocol: Uint8(h.Protocol()),
Checksum: Uint16(h.Checksum()),
SrcAddr: Address(h.SourceAddress()),
DstAddr: Address(h.DestinationAddress()),
Options: &options,
}
var nextParser layerParser
// If it is a fragment, don't treat it as having a transport protocol.
if h.FragmentOffset() != 0 || h.More() {
return &ipv4, bodySizeHint(h.PayloadLength()), parsePayload
}
switch h.TransportProtocol() {
case header.TCPProtocolNumber:
nextParser = parseTCP
case header.UDPProtocolNumber:
nextParser = parseUDP
case header.ICMPv4ProtocolNumber:
nextParser = parseICMPv4
default:
// Assume that the rest is a payload.
nextParser = parsePayload
}
return &ipv4, bodySizeHint(h.PayloadLength()), nextParser
}
func (l *IPv4) match(other Layer) bool {
return equalLayer(l, other)
}
func (l *IPv4) length() int {
if l.IHL == nil {
return header.IPv4MinimumSize
}
return int(*l.IHL)
}
// merge implements Layer.merge.
func (l *IPv4) merge(other Layer) error {
return mergeLayer(l, other)
}
// IPv6 can construct and match an IPv6 encapsulation.
type IPv6 struct {
LayerBase
TrafficClass *uint8
FlowLabel *uint32
PayloadLength *uint16
NextHeader *uint8
HopLimit *uint8
SrcAddr *net.IP
DstAddr *net.IP
}
func (l *IPv6) String() string {
return stringLayer(l)
}
// ToBytes implements Layer.ToBytes.
func (l *IPv6) ToBytes() ([]byte, error) {
b := make([]byte, header.IPv6MinimumSize)
h := header.IPv6(b)
fields := &header.IPv6Fields{
HopLimit: 64,
}
if l.TrafficClass != nil {
fields.TrafficClass = *l.TrafficClass
}
if l.FlowLabel != nil {
fields.FlowLabel = *l.FlowLabel
}
if l.PayloadLength != nil {
fields.PayloadLength = *l.PayloadLength
} else {
for current := l.next(); current != nil; current = current.next() {
fields.PayloadLength += uint16(current.length())
}
}
if l.NextHeader != nil {
fields.TransportProtocol = tcpip.TransportProtocolNumber(*l.NextHeader)
} else {
nh, err := nextHeaderByLayer(l.next())
if err != nil {
return nil, err
}
fields.TransportProtocol = tcpip.TransportProtocolNumber(nh)
}
if l.HopLimit != nil {
fields.HopLimit = *l.HopLimit
}
if l.SrcAddr != nil && len(*l.SrcAddr) > 0 {
fields.SrcAddr = tcpip.AddrFrom16Slice(*l.SrcAddr)
}
if l.DstAddr != nil && len(*l.DstAddr) > 0 {
fields.DstAddr = tcpip.AddrFrom16Slice(*l.DstAddr)
}
h.Encode(fields)
return h, nil
}
// nextIPv6PayloadParser finds the corresponding parser for nextHeader.
func nextIPv6PayloadParser(nextHeader uint8) layerParser {
switch tcpip.TransportProtocolNumber(nextHeader) {
case header.TCPProtocolNumber:
return parseTCP
case header.UDPProtocolNumber:
return parseUDP
case header.ICMPv6ProtocolNumber:
return parseICMPv6
}
switch header.IPv6ExtensionHeaderIdentifier(nextHeader) {
case header.IPv6HopByHopOptionsExtHdrIdentifier:
return parseIPv6HopByHopOptionsExtHdr
case header.IPv6DestinationOptionsExtHdrIdentifier:
return parseIPv6DestinationOptionsExtHdr
case header.IPv6FragmentExtHdrIdentifier:
return parseIPv6FragmentExtHdr
}
return parsePayload
}
// parseIPv6 parses the bytes assuming that they start with an ipv6 header and
// continues parsing further encapsulations.
func parseIPv6(b []byte) (Layer, bodySizeHint, layerParser) {
h := header.IPv6(b)
tos, flowLabel := h.TOS()
ipv6 := IPv6{
TrafficClass: &tos,
FlowLabel: &flowLabel,
PayloadLength: Uint16(h.PayloadLength()),
NextHeader: Uint8(h.NextHeader()),
HopLimit: Uint8(h.HopLimit()),
SrcAddr: Address(h.SourceAddress()),
DstAddr: Address(h.DestinationAddress()),
}
nextParser := nextIPv6PayloadParser(h.NextHeader())
return &ipv6, bodySizeHint(h.PayloadLength()), nextParser
}
func (l *IPv6) match(other Layer) bool {
return equalLayer(l, other)
}
func (l *IPv6) length() int {
return header.IPv6MinimumSize
}
// merge overrides the values in l with the values from other but only in fields
// where the value is not nil.
func (l *IPv6) merge(other Layer) error {
return mergeLayer(l, other)
}
// IPv6HopByHopOptionsExtHdr can construct and match an IPv6HopByHopOptions
// Extension Header.
type IPv6HopByHopOptionsExtHdr struct {
LayerBase
NextHeader *header.IPv6ExtensionHeaderIdentifier
Options []byte
}
// IPv6DestinationOptionsExtHdr can construct and match an IPv6DestinationOptions
// Extension Header.
type IPv6DestinationOptionsExtHdr struct {
LayerBase
NextHeader *header.IPv6ExtensionHeaderIdentifier
Options []byte
}
// IPv6FragmentExtHdr can construct and match an IPv6 Fragment Extension Header.
type IPv6FragmentExtHdr struct {
LayerBase
NextHeader *header.IPv6ExtensionHeaderIdentifier
FragmentOffset *uint16
MoreFragments *bool
Identification *uint32
}
// nextHeaderByLayer finds the correct next header protocol value for layer l.
func nextHeaderByLayer(l Layer) (uint8, error) {
if l == nil {
return uint8(header.IPv6NoNextHeaderIdentifier), nil
}
switch l.(type) {
case *TCP:
return uint8(header.TCPProtocolNumber), nil
case *UDP:
return uint8(header.UDPProtocolNumber), nil
case *ICMPv6:
return uint8(header.ICMPv6ProtocolNumber), nil
case *Payload:
return uint8(header.IPv6NoNextHeaderIdentifier), nil
case *IPv6HopByHopOptionsExtHdr:
return uint8(header.IPv6HopByHopOptionsExtHdrIdentifier), nil
case *IPv6DestinationOptionsExtHdr:
return uint8(header.IPv6DestinationOptionsExtHdrIdentifier), nil
case *IPv6FragmentExtHdr:
return uint8(header.IPv6FragmentExtHdrIdentifier), nil
default:
// TODO(b/161005083): Support more protocols as needed.
return 0, fmt.Errorf("failed to deduce the IPv6 header's next protocol: %T", l)
}
}
// ipv6OptionsExtHdrToBytes serializes an options extension header into bytes.
func ipv6OptionsExtHdrToBytes(nextHeader *header.IPv6ExtensionHeaderIdentifier, nextLayer Layer, options []byte) ([]byte, error) {
length := len(options) + 2
if length%8 != 0 {
return nil, fmt.Errorf("IPv6 extension headers must be a multiple of 8 octets long, but the length given: %d, options: %s", length, hex.Dump(options))
}
bytes := make([]byte, length)
if nextHeader != nil {
bytes[0] = byte(*nextHeader)
} else {
nh, err := nextHeaderByLayer(nextLayer)
if err != nil {
return nil, err
}
bytes[0] = nh
}
// ExtHdrLen field is the length of the extension header
// in 8-octet unit, ignoring the first 8 octets.
// https://tools.ietf.org/html/rfc2460#section-4.3
// https://tools.ietf.org/html/rfc2460#section-4.6
bytes[1] = uint8((length - 8) / 8)
copy(bytes[2:], options)
return bytes, nil
}
// IPv6ExtHdrIdent is a helper routine that allocates a new
// header.IPv6ExtensionHeaderIdentifier value to store v and returns a pointer
// to it.
func IPv6ExtHdrIdent(id header.IPv6ExtensionHeaderIdentifier) *header.IPv6ExtensionHeaderIdentifier {
return &id
}
// ToBytes implements Layer.ToBytes.
func (l *IPv6HopByHopOptionsExtHdr) ToBytes() ([]byte, error) {
return ipv6OptionsExtHdrToBytes(l.NextHeader, l.next(), l.Options)
}
// ToBytes implements Layer.ToBytes.
func (l *IPv6DestinationOptionsExtHdr) ToBytes() ([]byte, error) {
return ipv6OptionsExtHdrToBytes(l.NextHeader, l.next(), l.Options)
}
// ToBytes implements Layer.ToBytes.
func (l *IPv6FragmentExtHdr) ToBytes() ([]byte, error) {
var offset, mflag uint16
var ident uint32
bytes := make([]byte, header.IPv6FragmentExtHdrLength)
if l.NextHeader != nil {
bytes[0] = byte(*l.NextHeader)
} else {
nh, err := nextHeaderByLayer(l.next())
if err != nil {
return nil, err
}
bytes[0] = nh
}
bytes[1] = 0 // reserved
if l.MoreFragments != nil && *l.MoreFragments {
mflag = 1
}
if l.FragmentOffset != nil {
offset = *l.FragmentOffset
}
if l.Identification != nil {
ident = *l.Identification
}
offsetAndMflag := offset<<3 | mflag
binary.BigEndian.PutUint16(bytes[2:], offsetAndMflag)
binary.BigEndian.PutUint32(bytes[4:], ident)
return bytes, nil
}
// parseIPv6ExtHdr parses an IPv6 extension header and returns the NextHeader
// field, the rest of the payload and a parser function for the corresponding
// next extension header.
func parseIPv6ExtHdr(b []byte) (header.IPv6ExtensionHeaderIdentifier, []byte, layerParser) {
nextHeader := b[0]
// For HopByHop and Destination options extension headers,
// This field is the length of the extension header in
// 8-octet units, not including the first 8 octets.
// https://tools.ietf.org/html/rfc2460#section-4.3
// https://tools.ietf.org/html/rfc2460#section-4.6
length := b[1]*8 + 8
data := b[2:length]
nextParser := nextIPv6PayloadParser(nextHeader)
return header.IPv6ExtensionHeaderIdentifier(nextHeader), data, nextParser
}
// parseIPv6HopByHopOptionsExtHdr parses the bytes assuming that they start
// with an IPv6 HopByHop Options Extension Header.
func parseIPv6HopByHopOptionsExtHdr(b []byte) (Layer, bodySizeHint, layerParser) {
nextHeader, options, nextParser := parseIPv6ExtHdr(b)
return &IPv6HopByHopOptionsExtHdr{NextHeader: &nextHeader, Options: options}, bodySizeUnknown, nextParser
}
// parseIPv6DestinationOptionsExtHdr parses the bytes assuming that they start
// with an IPv6 Destination Options Extension Header.
func parseIPv6DestinationOptionsExtHdr(b []byte) (Layer, bodySizeHint, layerParser) {
nextHeader, options, nextParser := parseIPv6ExtHdr(b)
return &IPv6DestinationOptionsExtHdr{NextHeader: &nextHeader, Options: options}, bodySizeUnknown, nextParser
}
// Bool is a helper routine that allocates a new
// bool value to store v and returns a pointer to it.
func Bool(v bool) *bool {
return &v
}
// parseIPv6FragmentExtHdr parses the bytes assuming that they start
// with an IPv6 Fragment Extension Header.
func parseIPv6FragmentExtHdr(b []byte) (Layer, bodySizeHint, layerParser) {
nextHeader := b[0]
var extHdr header.IPv6FragmentExtHdr
copy(extHdr[:], b[2:])
fragLayer := IPv6FragmentExtHdr{
NextHeader: IPv6ExtHdrIdent(header.IPv6ExtensionHeaderIdentifier(nextHeader)),
FragmentOffset: Uint16(extHdr.FragmentOffset()),
MoreFragments: Bool(extHdr.More()),
Identification: Uint32(extHdr.ID()),
}
// If it is a fragment, we can't interpret it.
if extHdr.FragmentOffset() != 0 || extHdr.More() {
return &fragLayer, bodySizeUnknown, parsePayload
}
return &fragLayer, bodySizeUnknown, nextIPv6PayloadParser(nextHeader)
}
func (l *IPv6HopByHopOptionsExtHdr) length() int {
return len(l.Options) + 2
}
func (l *IPv6HopByHopOptionsExtHdr) match(other Layer) bool {
return equalLayer(l, other)
}
// merge overrides the values in l with the values from other but only in fields
// where the value is not nil.
func (l *IPv6HopByHopOptionsExtHdr) merge(other Layer) error {
return mergeLayer(l, other)
}
func (l *IPv6HopByHopOptionsExtHdr) String() string {
return stringLayer(l)
}
func (l *IPv6DestinationOptionsExtHdr) length() int {
return len(l.Options) + 2
}
func (l *IPv6DestinationOptionsExtHdr) match(other Layer) bool {
return equalLayer(l, other)
}
// merge overrides the values in l with the values from other but only in fields
// where the value is not nil.
func (l *IPv6DestinationOptionsExtHdr) merge(other Layer) error {
return mergeLayer(l, other)
}
func (l *IPv6DestinationOptionsExtHdr) String() string {
return stringLayer(l)
}
func (*IPv6FragmentExtHdr) length() int {
return header.IPv6FragmentExtHdrLength
}
func (l *IPv6FragmentExtHdr) match(other Layer) bool {
return equalLayer(l, other)
}
// merge overrides the values in l with the values from other but only in fields
// where the value is not nil.
func (l *IPv6FragmentExtHdr) merge(other Layer) error {
return mergeLayer(l, other)
}
func (l *IPv6FragmentExtHdr) String() string {
return stringLayer(l)
}
// ICMPv6 can construct and match an ICMPv6 encapsulation.
type ICMPv6 struct {
LayerBase
Type *header.ICMPv6Type
Code *header.ICMPv6Code
Checksum *uint16
Ident *uint16 // Only in Echo Request/Reply.
Pointer *uint32 // Only in Parameter Problem.
Payload []byte
}
func (l *ICMPv6) String() string {
// TODO(eyalsoha): Do something smarter here when *l.Type is ParameterProblem?
// We could parse the contents of the Payload as if it were an IPv6 packet.
return stringLayer(l)
}
// ToBytes implements Layer.ToBytes.
func (l *ICMPv6) ToBytes() ([]byte, error) {
b := make([]byte, header.ICMPv6MinimumSize+len(l.Payload))
h := header.ICMPv6(b)
if l.Type != nil {
h.SetType(*l.Type)
}
if l.Code != nil {
h.SetCode(*l.Code)
}
if n := copy(h.Payload(), l.Payload); n != len(l.Payload) {
panic(fmt.Sprintf("copied %d bytes, expected to copy %d bytes", n, len(l.Payload)))
}
typ := h.Type()
switch typ {
case header.ICMPv6EchoRequest, header.ICMPv6EchoReply:
if l.Ident != nil {
h.SetIdent(*l.Ident)
}
case header.ICMPv6ParamProblem:
if l.Pointer != nil {
h.SetTypeSpecific(*l.Pointer)
}
}
if l.Checksum != nil {
h.SetChecksum(*l.Checksum)
} else {
// It is possible that the ICMPv6 header does not follow the IPv6 header
// immediately, there could be one or more extension headers in between.
// We need to search backwards to find the IPv6 header.
for layer := l.Prev(); layer != nil; layer = layer.Prev() {
if ipv6, ok := layer.(*IPv6); ok {
h.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
Header: h[:header.ICMPv6PayloadOffset],
Src: tcpip.AddrFrom16Slice(*ipv6.SrcAddr),
Dst: tcpip.AddrFrom16Slice(*ipv6.DstAddr),
PayloadCsum: checksum.Checksum(l.Payload, 0 /* initial */),
PayloadLen: len(l.Payload),
}))
break
}
}
}
return h, nil
}
// ICMPv6Type is a helper routine that allocates a new ICMPv6Type value to store
// v and returns a pointer to it.
func ICMPv6Type(v header.ICMPv6Type) *header.ICMPv6Type {
return &v
}
// ICMPv6Code is a helper routine that allocates a new ICMPv6Type value to store
// v and returns a pointer to it.
func ICMPv6Code(v header.ICMPv6Code) *header.ICMPv6Code {
return &v
}
// parseICMPv6 parses the bytes assuming that they start with an ICMPv6 header.
func parseICMPv6(b []byte) (Layer, bodySizeHint, layerParser) {
h := header.ICMPv6(b)
msgType := h.Type()
icmpv6 := ICMPv6{
Type: ICMPv6Type(msgType),
Code: ICMPv6Code(h.Code()),
Checksum: Uint16(h.Checksum()),
Payload: h.Payload(),
}
switch msgType {
case header.ICMPv6EchoRequest, header.ICMPv6EchoReply:
icmpv6.Ident = Uint16(h.Ident())
case header.ICMPv6ParamProblem:
icmpv6.Pointer = Uint32(h.TypeSpecific())
}
return &icmpv6, bodySizeUnknown, nil
}
func (l *ICMPv6) match(other Layer) bool {
return equalLayer(l, other)
}
func (l *ICMPv6) length() int {
return header.ICMPv6MinimumSize + len(l.Payload)
}
// merge overrides the values in l with the values from other but only in fields
// where the value is not nil.
func (l *ICMPv6) merge(other Layer) error {
return mergeLayer(l, other)
}
// ICMPv4 can construct and match an ICMPv4 encapsulation.
type ICMPv4 struct {
LayerBase
Type *header.ICMPv4Type
Code *header.ICMPv4Code
Checksum *uint16
Ident *uint16 // Only in Echo Request/Reply.
Sequence *uint16 // Only in Echo Request/Reply.
Pointer *uint8 // Only in Parameter Problem.
Payload []byte
}
func (l *ICMPv4) String() string {
return stringLayer(l)
}
// ICMPv4Type is a helper routine that allocates a new header.ICMPv4Type value
// to store t and returns a pointer to it.
func ICMPv4Type(t header.ICMPv4Type) *header.ICMPv4Type {
return &t
}
// ICMPv4Code is a helper routine that allocates a new header.ICMPv4Code value
// to store t and returns a pointer to it.
func ICMPv4Code(t header.ICMPv4Code) *header.ICMPv4Code {
return &t
}
// ToBytes implements Layer.ToBytes.
func (l *ICMPv4) ToBytes() ([]byte, error) {
b := make([]byte, header.ICMPv4MinimumSize+len(l.Payload))
h := header.ICMPv4(b)
if l.Type != nil {
h.SetType(*l.Type)
}
if l.Code != nil {
h.SetCode(*l.Code)
}
if n := copy(h.Payload(), l.Payload); n != len(l.Payload) {
panic(fmt.Sprintf("wrong number of bytes copied into h.Payload(): got = %d, want = %d", n, len(l.Payload)))
}
typ := h.Type()
switch typ {
case header.ICMPv4EchoReply, header.ICMPv4Echo:
if l.Ident != nil {
h.SetIdent(*l.Ident)
}
if l.Sequence != nil {
h.SetSequence(*l.Sequence)
}