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-rw-r--r--pkg/tcpip/header/ipv4.go206
-rw-r--r--pkg/tcpip/header/ndp_options.go2
-rw-r--r--pkg/tcpip/network/ipv4/igmp.go4
-rw-r--r--pkg/tcpip/network/ipv4/ipv4.go31
-rw-r--r--pkg/tcpip/stack/registration.go13
5 files changed, 196 insertions, 60 deletions
diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go
index 5fddd2af6..e6103f4bc 100644
--- a/pkg/tcpip/header/ipv4.go
+++ b/pkg/tcpip/header/ipv4.go
@@ -100,7 +100,7 @@ type IPv4Fields struct {
//
// That leaves ten 32 bit (4 byte) fields for options. An attempt to encode
// more will fail.
- Options IPv4Options
+ Options IPv4OptionsSerializer
}
// IPv4 is an IPv4 header.
@@ -285,18 +285,17 @@ func (b IPv4) DestinationAddress() tcpip.Address {
return tcpip.Address(b[dstAddr : dstAddr+IPv4AddressSize])
}
-// IPv4Options is a buffer that holds all the raw IP options.
-type IPv4Options []byte
-
-// SizeWithPadding implements stack.NetOptions.
-// It reports the size to allocate for the Options. RFC 791 page 23 (end of
-// section 3.1) says of the padding at the end of the options:
+// padIPv4OptionsLength returns the total length for IPv4 options of length l
+// after applying padding according to RFC 791:
// The internet header padding is used to ensure that the internet
// header ends on a 32 bit boundary.
-func (o IPv4Options) SizeWithPadding() int {
- return (len(o) + IPv4IHLStride - 1) & ^(IPv4IHLStride - 1)
+func padIPv4OptionsLength(length uint8) uint8 {
+ return (length + IPv4IHLStride - 1) & ^uint8(IPv4IHLStride-1)
}
+// IPv4Options is a buffer that holds all the raw IP options.
+type IPv4Options []byte
+
// Options returns a buffer holding the options.
func (b IPv4) Options() IPv4Options {
hdrLen := b.HeaderLength()
@@ -375,26 +374,16 @@ func (b IPv4) CalculateChecksum() uint16 {
func (b IPv4) Encode(i *IPv4Fields) {
// The size of the options defines the size of the whole header and thus the
// IHL field. Options are rare and this is a heavily used function so it is
- // worth a bit of optimisation here to keep the copy out of the fast path.
- hdrLen := IPv4MinimumSize
+ // worth a bit of optimisation here to keep the serializer out of the fast
+ // path.
+ hdrLen := uint8(IPv4MinimumSize)
if len(i.Options) != 0 {
- // SizeWithPadding is always >= len(i.Options).
- aLen := i.Options.SizeWithPadding()
- hdrLen += aLen
- if hdrLen > len(b) {
- panic(fmt.Sprintf("encode received %d bytes, wanted >= %d", len(b), hdrLen))
- }
- opts := b[options:]
- // This avoids bounds checks on the next line(s) which would happen even
- // if there's no work to do.
- if n := copy(opts, i.Options); n != aLen {
- padding := opts[n:][:aLen-n]
- for i := range padding {
- padding[i] = 0
- }
- }
+ hdrLen += i.Options.Serialize(b[options:])
}
- b.SetHeaderLength(uint8(hdrLen))
+ if hdrLen > IPv4MaximumHeaderSize {
+ panic(fmt.Sprintf("%d is larger than maximum IPv4 header size of %d", hdrLen, IPv4MaximumHeaderSize))
+ }
+ b.SetHeaderLength(hdrLen)
b[tos] = i.TOS
b.SetTotalLength(i.TotalLength)
binary.BigEndian.PutUint16(b[id:], i.ID)
@@ -474,6 +463,10 @@ const (
// options and may appear multiple times.
IPv4OptionNOPType IPv4OptionType = 1
+ // IPv4OptionRouterAlertType is the option type for the Router Alert option,
+ // defined in RFC 2113 Section 2.1.
+ IPv4OptionRouterAlertType IPv4OptionType = 20 | 0x80
+
// IPv4OptionRecordRouteType is used by each router on the path of the packet
// to record its path. It is carried over to an Echo Reply.
IPv4OptionRecordRouteType IPv4OptionType = 7
@@ -874,3 +867,162 @@ func (rr *IPv4OptionRecordRoute) Size() uint8 { return uint8(len(*rr)) }
// Contents implements IPv4Option.
func (rr *IPv4OptionRecordRoute) Contents() []byte { return []byte(*rr) }
+
+// Router Alert option specific related constants.
+//
+// from RFC 2113 section 2.1:
+//
+// +--------+--------+--------+--------+
+// |10010100|00000100| 2 octet value |
+// +--------+--------+--------+--------+
+//
+// Type:
+// Copied flag: 1 (all fragments must carry the option)
+// Option class: 0 (control)
+// Option number: 20 (decimal)
+//
+// Length: 4
+//
+// Value: A two octet code with the following values:
+// 0 - Router shall examine packet
+// 1-65535 - Reserved
+const (
+ // IPv4OptionRouterAlertLength is the length of a Router Alert option.
+ IPv4OptionRouterAlertLength = 4
+
+ // IPv4OptionRouterAlertValue is the only permissible value of the 16 bit
+ // payload of the router alert option.
+ IPv4OptionRouterAlertValue = 0
+
+ // iPv4OptionRouterAlertValueOffset is the offset for the value of a
+ // RouterAlert option.
+ iPv4OptionRouterAlertValueOffset = 2
+)
+
+// IPv4SerializableOption is an interface to represent serializable IPv4 option
+// types.
+type IPv4SerializableOption interface {
+ // optionType returns the type identifier of the option.
+ optionType() IPv4OptionType
+}
+
+// IPv4SerializableOptionPayload is an interface providing serialization of the
+// payload of an IPv4 option.
+type IPv4SerializableOptionPayload interface {
+ // length returns the size of the payload.
+ length() uint8
+
+ // serializeInto serializes the payload into the provided byte buffer.
+ //
+ // Note, the caller MUST provide a byte buffer with size of at least
+ // Length. Implementers of this function may assume that the byte buffer
+ // is of sufficient size. serializeInto MUST panic if the provided byte
+ // buffer is not of sufficient size.
+ //
+ // serializeInto will return the number of bytes that was used to
+ // serialize the receiver. Implementers must only use the number of
+ // bytes required to serialize the receiver. Callers MAY provide a
+ // larger buffer than required to serialize into.
+ serializeInto(buffer []byte) uint8
+}
+
+// IPv4OptionsSerializer is a serializer for IPv4 options.
+type IPv4OptionsSerializer []IPv4SerializableOption
+
+// Length returns the total number of bytes required to serialize the options.
+func (s IPv4OptionsSerializer) Length() uint8 {
+ var total uint8
+ for _, opt := range s {
+ total++
+ if withPayload, ok := opt.(IPv4SerializableOptionPayload); ok {
+ // Add 1 to reported length to account for the length byte.
+ total += 1 + withPayload.length()
+ }
+ }
+ return padIPv4OptionsLength(total)
+}
+
+// Serialize serializes the provided list of IPV4 options into b.
+//
+// Note, b must be of sufficient size to hold all the options in s. See
+// IPv4OptionsSerializer.Length for details on the getting the total size
+// of a serialized IPv4OptionsSerializer.
+//
+// Serialize panics if b is not of sufficient size to hold all the options in s.
+func (s IPv4OptionsSerializer) Serialize(b []byte) uint8 {
+ var total uint8
+ for _, opt := range s {
+ ty := opt.optionType()
+ if withPayload, ok := opt.(IPv4SerializableOptionPayload); ok {
+ // Serialize first to reduce bounds checks.
+ l := 2 + withPayload.serializeInto(b[2:])
+ b[0] = byte(ty)
+ b[1] = l
+ b = b[l:]
+ total += l
+ continue
+ }
+ // Options without payload consist only of the type field.
+ //
+ // NB: Repeating code from the branch above is intentional to minimize
+ // bounds checks.
+ b[0] = byte(ty)
+ b = b[1:]
+ total++
+ }
+
+ // According to RFC 791:
+ //
+ // The internet header padding is used to ensure that the internet
+ // header ends on a 32 bit boundary. The padding is zero.
+ padded := padIPv4OptionsLength(total)
+ b = b[:padded-total]
+ for i := range b {
+ b[i] = 0
+ }
+ return padded
+}
+
+var _ IPv4SerializableOptionPayload = (*IPv4SerializableRouterAlertOption)(nil)
+var _ IPv4SerializableOption = (*IPv4SerializableRouterAlertOption)(nil)
+
+// IPv4SerializableRouterAlertOption provides serialization of the Router Alert
+// IPv4 option according to RFC 2113.
+type IPv4SerializableRouterAlertOption struct{}
+
+// Type implements IPv4SerializableOption.
+func (*IPv4SerializableRouterAlertOption) optionType() IPv4OptionType {
+ return IPv4OptionRouterAlertType
+}
+
+// Length implements IPv4SerializableOption.
+func (*IPv4SerializableRouterAlertOption) length() uint8 {
+ return IPv4OptionRouterAlertLength - iPv4OptionRouterAlertValueOffset
+}
+
+// SerializeInto implements IPv4SerializableOption.
+func (o *IPv4SerializableRouterAlertOption) serializeInto(buffer []byte) uint8 {
+ binary.BigEndian.PutUint16(buffer, IPv4OptionRouterAlertValue)
+ return o.length()
+}
+
+var _ IPv4SerializableOption = (*IPv4SerializableNOPOption)(nil)
+
+// IPv4SerializableNOPOption provides serialization for the IPv4 no-op option.
+type IPv4SerializableNOPOption struct{}
+
+// Type implements IPv4SerializableOption.
+func (*IPv4SerializableNOPOption) optionType() IPv4OptionType {
+ return IPv4OptionNOPType
+}
+
+var _ IPv4SerializableOption = (*IPv4SerializableListEndOption)(nil)
+
+// IPv4SerializableListEndOption provides serialization for the IPv4 List End
+// option.
+type IPv4SerializableListEndOption struct{}
+
+// Type implements IPv4SerializableOption.
+func (*IPv4SerializableListEndOption) optionType() IPv4OptionType {
+ return IPv4OptionListEndType
+}
diff --git a/pkg/tcpip/header/ndp_options.go b/pkg/tcpip/header/ndp_options.go
index 5d3975c56..554242f0c 100644
--- a/pkg/tcpip/header/ndp_options.go
+++ b/pkg/tcpip/header/ndp_options.go
@@ -298,7 +298,7 @@ func (b NDPOptions) Iter(check bool) (NDPOptionIterator, error) {
return it, nil
}
-// Serialize serializes the provided list of NDP options into o.
+// Serialize serializes the provided list of NDP options into b.
//
// Note, b must be of sufficient size to hold all the options in s. See
// NDPOptionsSerializer.Length for details on the getting the total size
diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index 18ccd28c3..0134fadc0 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -250,10 +250,10 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
Protocol: header.IGMPProtocolNumber,
TTL: header.IGMPTTL,
TOS: stack.DefaultTOS,
+ }, header.IPv4OptionsSerializer{
+ &header.IPv4SerializableRouterAlertOption{},
})
- // TODO(b/162198658): set the ROUTER_ALERT option when sending Host
- // Membership Reports.
sent := igmp.ep.protocol.stack.Stats().IGMP.PacketsSent
if err := igmp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv4Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
sent.Dropped.Increment()
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 354ac1e1d..4b34d0bfb 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -215,21 +215,18 @@ func (e *endpoint) NetworkProtocolNumber() tcpip.NetworkProtocolNumber {
return e.protocol.Number()
}
-func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.PacketBuffer, params stack.NetworkHeaderParams) {
+func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.PacketBuffer, params stack.NetworkHeaderParams, options header.IPv4OptionsSerializer) {
hdrLen := header.IPv4MinimumSize
- var opts header.IPv4Options
- if params.Options != nil {
- var ok bool
- if opts, ok = params.Options.(header.IPv4Options); !ok {
- panic(fmt.Sprintf("want IPv4Options, got %T", params.Options))
- }
- hdrLen += opts.SizeWithPadding()
- if hdrLen > header.IPv4MaximumHeaderSize {
- // Since we have no way to report an error we must either panic or create
- // a packet which is different to what was requested. Choose panic as this
- // would be a programming error that should be caught in testing.
- panic(fmt.Sprintf("IPv4 Options %d bytes, Max %d", params.Options.SizeWithPadding(), header.IPv4MaximumOptionsSize))
- }
+ var optLen int
+ if options != nil {
+ optLen = int(options.Length())
+ }
+ hdrLen += optLen
+ if hdrLen > header.IPv4MaximumHeaderSize {
+ // Since we have no way to report an error we must either panic or create
+ // a packet which is different to what was requested. Choose panic as this
+ // would be a programming error that should be caught in testing.
+ panic(fmt.Sprintf("IPv4 Options %d bytes, Max %d", optLen, header.IPv4MaximumOptionsSize))
}
ip := header.IPv4(pkt.NetworkHeader().Push(hdrLen))
length := uint16(pkt.Size())
@@ -245,7 +242,7 @@ func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.Packet
Protocol: uint8(params.Protocol),
SrcAddr: srcAddr,
DstAddr: dstAddr,
- Options: opts,
+ Options: options,
})
ip.SetChecksum(^ip.CalculateChecksum())
pkt.NetworkProtocolNumber = ProtocolNumber
@@ -276,7 +273,7 @@ func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU ui
// WritePacket writes a packet to the given destination address and protocol.
func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) *tcpip.Error {
- e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params)
+ e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params, nil /* options */)
// iptables filtering. All packets that reach here are locally
// generated.
@@ -364,7 +361,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
}
for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
- e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params)
+ e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params, nil /* options */)
networkMTU, err := calculateNetworkMTU(e.nic.MTU(), uint32(pkt.NetworkHeader().View().Size()))
if err != nil {
r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(pkts.Len()))
diff --git a/pkg/tcpip/stack/registration.go b/pkg/tcpip/stack/registration.go
index 236e4e4c7..b334e27c4 100644
--- a/pkg/tcpip/stack/registration.go
+++ b/pkg/tcpip/stack/registration.go
@@ -259,15 +259,6 @@ const (
PacketLoop
)
-// NetOptions is an interface that allows us to pass network protocol specific
-// options through the Stack layer code.
-type NetOptions interface {
- // SizeWithPadding returns the amount of memory that must be allocated to
- // hold the options given that the value must be rounded up to the next
- // multiple of 4 bytes.
- SizeWithPadding() int
-}
-
// NetworkHeaderParams are the header parameters given as input by the
// transport endpoint to the network.
type NetworkHeaderParams struct {
@@ -279,10 +270,6 @@ type NetworkHeaderParams struct {
// TOS refers to TypeOfService or TrafficClass field of the IP-header.
TOS uint8
-
- // Options is a set of options to add to a network header (or nil).
- // It will be protocol specific opaque information from higher layers.
- Options NetOptions
}
// GroupAddressableEndpoint is an endpoint that supports group addressing.