diff options
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 206 | ||||
| -rw-r--r-- | pkg/tcpip/header/ndp_options.go | 2 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv4/igmp.go | 4 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4.go | 31 | ||||
| -rw-r--r-- | pkg/tcpip/stack/registration.go | 13 |
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. |