diff options
Diffstat (limited to 'pkg/tcpip/header')
| -rw-r--r-- | pkg/tcpip/header/BUILD | 5 | ||||
| -rw-r--r-- | pkg/tcpip/header/icmpv4.go | 9 | ||||
| -rw-r--r-- | pkg/tcpip/header/icmpv6.go | 13 | ||||
| -rw-r--r-- | pkg/tcpip/header/igmp.go | 181 | ||||
| -rw-r--r-- | pkg/tcpip/header/igmp_test.go | 110 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 702 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipv4_test.go | 179 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipv6.go | 36 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipv6_extension_headers.go | 335 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipv6_extension_headers_test.go | 331 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipv6_fragment.go | 42 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipversion_test.go | 2 | ||||
| -rw-r--r-- | pkg/tcpip/header/mld.go | 103 | ||||
| -rw-r--r-- | pkg/tcpip/header/mld_test.go | 61 | ||||
| -rw-r--r-- | pkg/tcpip/header/ndp_options.go | 2 | ||||
| -rw-r--r-- | pkg/tcpip/header/parse/parse.go | 3 | ||||
| -rw-r--r-- | pkg/tcpip/header/udp.go | 29 |
17 files changed, 2053 insertions, 90 deletions
diff --git a/pkg/tcpip/header/BUILD b/pkg/tcpip/header/BUILD index d87797617..0bdc12d53 100644 --- a/pkg/tcpip/header/BUILD +++ b/pkg/tcpip/header/BUILD @@ -11,11 +11,13 @@ go_library( "gue.go", "icmpv4.go", "icmpv6.go", + "igmp.go", "interfaces.go", "ipv4.go", "ipv6.go", "ipv6_extension_headers.go", "ipv6_fragment.go", + "mld.go", "ndp_neighbor_advert.go", "ndp_neighbor_solicit.go", "ndp_options.go", @@ -39,6 +41,8 @@ go_test( size = "small", srcs = [ "checksum_test.go", + "igmp_test.go", + "ipv4_test.go", "ipv6_test.go", "ipversion_test.go", "tcp_test.go", @@ -58,6 +62,7 @@ go_test( srcs = [ "eth_test.go", "ipv6_extension_headers_test.go", + "mld_test.go", "ndp_test.go", ], library = ":header", diff --git a/pkg/tcpip/header/icmpv4.go b/pkg/tcpip/header/icmpv4.go index 504408878..2f13dea6a 100644 --- a/pkg/tcpip/header/icmpv4.go +++ b/pkg/tcpip/header/icmpv4.go @@ -99,7 +99,8 @@ const ( // ICMP codes for ICMPv4 Time Exceeded messages as defined in RFC 792. const ( - ICMPv4TTLExceeded ICMPv4Code = 0 + ICMPv4TTLExceeded ICMPv4Code = 0 + ICMPv4ReassemblyTimeout ICMPv4Code = 1 ) // ICMP codes for ICMPv4 Destination Unreachable messages as defined in RFC 792. @@ -126,6 +127,12 @@ func (b ICMPv4) Code() ICMPv4Code { return ICMPv4Code(b[1]) } // SetCode sets the ICMP code field. func (b ICMPv4) SetCode(c ICMPv4Code) { b[1] = byte(c) } +// Pointer returns the pointer field in a Parameter Problem packet. +func (b ICMPv4) Pointer() byte { return b[icmpv4PointerOffset] } + +// SetPointer sets the pointer field in a Parameter Problem packet. +func (b ICMPv4) SetPointer(c byte) { b[icmpv4PointerOffset] = c } + // Checksum is the ICMP checksum field. func (b ICMPv4) Checksum() uint16 { return binary.BigEndian.Uint16(b[icmpv4ChecksumOffset:]) diff --git a/pkg/tcpip/header/icmpv6.go b/pkg/tcpip/header/icmpv6.go index 4303fc5d5..2eef64b4d 100644 --- a/pkg/tcpip/header/icmpv6.go +++ b/pkg/tcpip/header/icmpv6.go @@ -115,6 +115,12 @@ const ( ICMPv6NeighborSolicit ICMPv6Type = 135 ICMPv6NeighborAdvert ICMPv6Type = 136 ICMPv6RedirectMsg ICMPv6Type = 137 + + // Multicast Listener Discovery (MLD) messages, see RFC 2710. + + ICMPv6MulticastListenerQuery ICMPv6Type = 130 + ICMPv6MulticastListenerReport ICMPv6Type = 131 + ICMPv6MulticastListenerDone ICMPv6Type = 132 ) // IsErrorType returns true if the receiver is an ICMP error type. @@ -245,10 +251,9 @@ func (b ICMPv6) SetSequence(sequence uint16) { binary.BigEndian.PutUint16(b[icmpv6SequenceOffset:], sequence) } -// NDPPayload returns the NDP payload buffer. That is, it returns the ICMPv6 -// packet's message body as defined by RFC 4443 section 2.1; the portion of the -// ICMPv6 buffer after the first ICMPv6HeaderSize bytes. -func (b ICMPv6) NDPPayload() []byte { +// MessageBody returns the message body as defined by RFC 4443 section 2.1; the +// portion of the ICMPv6 buffer after the first ICMPv6HeaderSize bytes. +func (b ICMPv6) MessageBody() []byte { return b[ICMPv6HeaderSize:] } diff --git a/pkg/tcpip/header/igmp.go b/pkg/tcpip/header/igmp.go new file mode 100644 index 000000000..5c5be1b9d --- /dev/null +++ b/pkg/tcpip/header/igmp.go @@ -0,0 +1,181 @@ +// 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 header + +import ( + "encoding/binary" + "fmt" + "time" + + "gvisor.dev/gvisor/pkg/tcpip" +) + +// IGMP represents an IGMP header stored in a byte array. +type IGMP []byte + +// IGMP implements `Transport`. +var _ Transport = (*IGMP)(nil) + +const ( + // IGMPMinimumSize is the minimum size of a valid IGMP packet in bytes, + // as per RFC 2236, Section 2, Page 2. + IGMPMinimumSize = 8 + + // IGMPQueryMinimumSize is the minimum size of a valid Membership Query + // Message in bytes, as per RFC 2236, Section 2, Page 2. + IGMPQueryMinimumSize = 8 + + // IGMPReportMinimumSize is the minimum size of a valid Report Message in + // bytes, as per RFC 2236, Section 2, Page 2. + IGMPReportMinimumSize = 8 + + // IGMPLeaveMessageMinimumSize is the minimum size of a valid Leave Message + // in bytes, as per RFC 2236, Section 2, Page 2. + IGMPLeaveMessageMinimumSize = 8 + + // IGMPTTL is the TTL for all IGMP messages, as per RFC 2236, Section 3, Page + // 3. + IGMPTTL = 1 + + // igmpTypeOffset defines the offset of the type field in an IGMP message. + igmpTypeOffset = 0 + + // igmpMaxRespTimeOffset defines the offset of the MaxRespTime field in an + // IGMP message. + igmpMaxRespTimeOffset = 1 + + // igmpChecksumOffset defines the offset of the checksum field in an IGMP + // message. + igmpChecksumOffset = 2 + + // igmpGroupAddressOffset defines the offset of the Group Address field in an + // IGMP message. + igmpGroupAddressOffset = 4 + + // IGMPProtocolNumber is IGMP's transport protocol number. + IGMPProtocolNumber tcpip.TransportProtocolNumber = 2 +) + +// IGMPType is the IGMP type field as per RFC 2236. +type IGMPType byte + +// Values for the IGMP Type described in RFC 2236 Section 2.1, Page 2. +// Descriptions below come from there. +const ( + // IGMPMembershipQuery indicates that the message type is Membership Query. + // "There are two sub-types of Membership Query messages: + // - General Query, used to learn which groups have members on an + // attached network. + // - Group-Specific Query, used to learn if a particular group + // has any members on an attached network. + // These two messages are differentiated by the Group Address, as + // described in section 1.4 ." + IGMPMembershipQuery IGMPType = 0x11 + // IGMPv1MembershipReport indicates that the message is a Membership Report + // generated by a host using the IGMPv1 protocol: "an additional type of + // message, for backwards-compatibility with IGMPv1" + IGMPv1MembershipReport IGMPType = 0x12 + // IGMPv2MembershipReport indicates that the Message type is a Membership + // Report generated by a host using the IGMPv2 protocol. + IGMPv2MembershipReport IGMPType = 0x16 + // IGMPLeaveGroup indicates that the message type is a Leave Group + // notification message. + IGMPLeaveGroup IGMPType = 0x17 +) + +// Type is the IGMP type field. +func (b IGMP) Type() IGMPType { return IGMPType(b[igmpTypeOffset]) } + +// SetType sets the IGMP type field. +func (b IGMP) SetType(t IGMPType) { b[igmpTypeOffset] = byte(t) } + +// MaxRespTime gets the MaxRespTimeField. This is meaningful only in Membership +// Query messages, in other cases it is set to 0 by the sender and ignored by +// the receiver. +func (b IGMP) MaxRespTime() time.Duration { + // As per RFC 2236 section 2.2, + // + // The Max Response Time field is meaningful only in Membership Query + // messages, and specifies the maximum allowed time before sending a + // responding report in units of 1/10 second. In all other messages, it + // is set to zero by the sender and ignored by receivers. + return DecisecondToDuration(b[igmpMaxRespTimeOffset]) +} + +// SetMaxRespTime sets the MaxRespTimeField. +func (b IGMP) SetMaxRespTime(m byte) { b[igmpMaxRespTimeOffset] = m } + +// Checksum is the IGMP checksum field. +func (b IGMP) Checksum() uint16 { + return binary.BigEndian.Uint16(b[igmpChecksumOffset:]) +} + +// SetChecksum sets the IGMP checksum field. +func (b IGMP) SetChecksum(checksum uint16) { + binary.BigEndian.PutUint16(b[igmpChecksumOffset:], checksum) +} + +// GroupAddress gets the Group Address field. +func (b IGMP) GroupAddress() tcpip.Address { + return tcpip.Address(b[igmpGroupAddressOffset:][:IPv4AddressSize]) +} + +// SetGroupAddress sets the Group Address field. +func (b IGMP) SetGroupAddress(address tcpip.Address) { + if n := copy(b[igmpGroupAddressOffset:], address); n != IPv4AddressSize { + panic(fmt.Sprintf("copied %d bytes, expected %d", n, IPv4AddressSize)) + } +} + +// SourcePort implements Transport.SourcePort. +func (IGMP) SourcePort() uint16 { + return 0 +} + +// DestinationPort implements Transport.DestinationPort. +func (IGMP) DestinationPort() uint16 { + return 0 +} + +// SetSourcePort implements Transport.SetSourcePort. +func (IGMP) SetSourcePort(uint16) { +} + +// SetDestinationPort implements Transport.SetDestinationPort. +func (IGMP) SetDestinationPort(uint16) { +} + +// Payload implements Transport.Payload. +func (IGMP) Payload() []byte { + return nil +} + +// IGMPCalculateChecksum calculates the IGMP checksum over the provided IGMP +// header. +func IGMPCalculateChecksum(h IGMP) uint16 { + // The header contains a checksum itself, set it aside to avoid checksumming + // the checksum and replace it afterwards. + existingXsum := h.Checksum() + h.SetChecksum(0) + xsum := ^Checksum(h, 0) + h.SetChecksum(existingXsum) + return xsum +} + +// DecisecondToDuration converts a value representing deci-seconds to a +// time.Duration. +func DecisecondToDuration(ds uint8) time.Duration { + return time.Duration(ds) * time.Second / 10 +} diff --git a/pkg/tcpip/header/igmp_test.go b/pkg/tcpip/header/igmp_test.go new file mode 100644 index 000000000..b6126d29a --- /dev/null +++ b/pkg/tcpip/header/igmp_test.go @@ -0,0 +1,110 @@ +// 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 header_test + +import ( + "testing" + "time" + + "gvisor.dev/gvisor/pkg/tcpip" + "gvisor.dev/gvisor/pkg/tcpip/header" +) + +// TestIGMPHeader tests the functions within header.igmp +func TestIGMPHeader(t *testing.T) { + const maxRespTimeTenthSec = 0xF0 + b := []byte{ + 0x11, // IGMP Type, Membership Query + maxRespTimeTenthSec, // Maximum Response Time + 0xC0, 0xC0, // Checksum + 0x01, 0x02, 0x03, 0x04, // Group Address + } + + igmpHeader := header.IGMP(b) + + if got, want := igmpHeader.Type(), header.IGMPMembershipQuery; got != want { + t.Errorf("got igmpHeader.Type() = %x, want = %x", got, want) + } + + if got, want := igmpHeader.MaxRespTime(), header.DecisecondToDuration(maxRespTimeTenthSec); got != want { + t.Errorf("got igmpHeader.MaxRespTime() = %s, want = %s", got, want) + } + + if got, want := igmpHeader.Checksum(), uint16(0xC0C0); got != want { + t.Errorf("got igmpHeader.Checksum() = %x, want = %x", got, want) + } + + if got, want := igmpHeader.GroupAddress(), tcpip.Address("\x01\x02\x03\x04"); got != want { + t.Errorf("got igmpHeader.GroupAddress() = %s, want = %s", got, want) + } + + igmpType := header.IGMPv2MembershipReport + igmpHeader.SetType(igmpType) + if got := igmpHeader.Type(); got != igmpType { + t.Errorf("got igmpHeader.Type() = %x, want = %x", got, igmpType) + } + if got := header.IGMPType(b[0]); got != igmpType { + t.Errorf("got IGMPtype in backing buffer = %x, want %x", got, igmpType) + } + + respTime := byte(0x02) + igmpHeader.SetMaxRespTime(respTime) + if got, want := igmpHeader.MaxRespTime(), header.DecisecondToDuration(respTime); got != want { + t.Errorf("got igmpHeader.MaxRespTime() = %s, want = %s", got, want) + } + + checksum := uint16(0x0102) + igmpHeader.SetChecksum(checksum) + if got := igmpHeader.Checksum(); got != checksum { + t.Errorf("got igmpHeader.Checksum() = %x, want = %x", got, checksum) + } + + groupAddress := tcpip.Address("\x04\x03\x02\x01") + igmpHeader.SetGroupAddress(groupAddress) + if got := igmpHeader.GroupAddress(); got != groupAddress { + t.Errorf("got igmpHeader.GroupAddress() = %s, want = %s", got, groupAddress) + } +} + +// TestIGMPChecksum ensures that the checksum calculator produces the expected +// checksum. +func TestIGMPChecksum(t *testing.T) { + b := []byte{ + 0x11, // IGMP Type, Membership Query + 0xF0, // Maximum Response Time + 0xC0, 0xC0, // Checksum + 0x01, 0x02, 0x03, 0x04, // Group Address + } + + igmpHeader := header.IGMP(b) + + // Calculate the initial checksum after setting the checksum temporarily to 0 + // to avoid checksumming the checksum. + initialChecksum := igmpHeader.Checksum() + igmpHeader.SetChecksum(0) + checksum := ^header.Checksum(b, 0) + igmpHeader.SetChecksum(initialChecksum) + + if got := header.IGMPCalculateChecksum(igmpHeader); got != checksum { + t.Errorf("got IGMPCalculateChecksum = %x, want %x", got, checksum) + } +} + +func TestDecisecondToDuration(t *testing.T) { + const valueInDeciseconds = 5 + if got, want := header.DecisecondToDuration(valueInDeciseconds), valueInDeciseconds*time.Second/10; got != want { + t.Fatalf("got header.DecisecondToDuration(%d) = %s, want = %s", valueInDeciseconds, got, want) + } +} diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go index 4c6e4be64..e6103f4bc 100644 --- a/pkg/tcpip/header/ipv4.go +++ b/pkg/tcpip/header/ipv4.go @@ -16,6 +16,7 @@ package header import ( "encoding/binary" + "errors" "fmt" "gvisor.dev/gvisor/pkg/tcpip" @@ -38,7 +39,6 @@ import ( // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // | Options | Padding | // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -// const ( versIHL = 0 tos = 1 @@ -56,12 +56,9 @@ const ( ) // IPv4Fields contains the fields of an IPv4 packet. It is used to describe the -// fields of a packet that needs to be encoded. +// fields of a packet that needs to be encoded. The IHL field is not here as +// it is totally defined by the size of the options. type IPv4Fields struct { - // IHL is the "internet header length" field of an IPv4 packet. The value - // is in bytes. - IHL uint8 - // TOS is the "type of service" field of an IPv4 packet. TOS uint8 @@ -91,9 +88,22 @@ type IPv4Fields struct { // DstAddr is the "destination ip address" of an IPv4 packet. DstAddr tcpip.Address + + // Options must be 40 bytes or less as they must fit along with the + // rest of the IPv4 header into the maximum size describable in the + // IHL field. RFC 791 section 3.1 says: + // IHL: 4 bits + // + // Internet Header Length is the length of the internet header in 32 + // bit words, and thus points to the beginning of the data. Note that + // the minimum value for a correct header is 5. + // + // That leaves ten 32 bit (4 byte) fields for options. An attempt to encode + // more will fail. + Options IPv4OptionsSerializer } -// IPv4 represents an ipv4 header stored in a byte array. +// IPv4 is an IPv4 header. // Most of the methods of IPv4 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 IPv4 before using other @@ -106,16 +116,19 @@ const ( IPv4MinimumSize = 20 // IPv4MaximumHeaderSize is the maximum size of an IPv4 header. Given - // that there are only 4 bits to represents the header length in 32-bit - // units, the header cannot exceed 15*4 = 60 bytes. + // that there are only 4 bits (max 0xF (15)) to represent the header length + // in 32-bit (4 byte) units, the header cannot exceed 15*4 = 60 bytes. IPv4MaximumHeaderSize = 60 + // IPv4MaximumOptionsSize is the largest size the IPv4 options can be. + IPv4MaximumOptionsSize = IPv4MaximumHeaderSize - IPv4MinimumSize + // IPv4MaximumPayloadSize is the maximum size of a valid IPv4 payload. // // Linux limits this to 65,515 octets (the max IP datagram size - the IPv4 // header size). But RFC 791 section 3.2 discusses the design of the IPv4 // fragment "allows 2**13 = 8192 fragments of 8 octets each for a total of - // 65,536 octets. Note that this is consistent with the the datagram total + // 65,536 octets. Note that this is consistent with the datagram total // length field (of course, the header is counted in the total length and not // in the fragments)." IPv4MaximumPayloadSize = 65536 @@ -130,7 +143,7 @@ const ( // IPv4ProtocolNumber is IPv4's network protocol number. IPv4ProtocolNumber tcpip.NetworkProtocolNumber = 0x0800 - // IPv4Version is the version of the ipv4 protocol. + // IPv4Version is the version of the IPv4 protocol. IPv4Version = 4 // IPv4AllSystems is the all systems IPv4 multicast address as per @@ -144,10 +157,20 @@ const ( // IPv4Any is the non-routable IPv4 "any" meta address. IPv4Any tcpip.Address = "\x00\x00\x00\x00" + // IPv4AllRoutersGroup is a multicast address for all routers. + IPv4AllRoutersGroup tcpip.Address = "\xe0\x00\x00\x02" + // IPv4MinimumProcessableDatagramSize is the minimum size of an IP // packet that every IPv4 capable host must be able to // process/reassemble. IPv4MinimumProcessableDatagramSize = 576 + + // IPv4MinimumMTU is the minimum MTU required by IPv4, per RFC 791, + // section 3.2: + // Every internet module must be able to forward a datagram of 68 octets + // without further fragmentation. This is because an internet header may be + // up to 60 octets, and the minimum fragment is 8 octets. + IPv4MinimumMTU = 68 ) // Flags that may be set in an IPv4 packet. @@ -191,14 +214,13 @@ func IPVersion(b []byte) int { // Internet Header Length is the length of the internet header in 32 // bit words, and thus points to the beginning of the data. Note that // the minimum value for a correct header is 5. -// const ( ipVersionShift = 4 ipIHLMask = 0x0f IPv4IHLStride = 4 ) -// HeaderLength returns the value of the "header length" field of the ipv4 +// HeaderLength returns the value of the "header length" field of the IPv4 // header. The length returned is in bytes. func (b IPv4) HeaderLength() uint8 { return (b[versIHL] & ipIHLMask) * IPv4IHLStride @@ -212,17 +234,17 @@ func (b IPv4) SetHeaderLength(hdrLen uint8) { b[versIHL] = (IPv4Version << ipVersionShift) | ((hdrLen / IPv4IHLStride) & ipIHLMask) } -// ID returns the value of the identifier field of the ipv4 header. +// ID returns the value of the identifier field of the IPv4 header. func (b IPv4) ID() uint16 { return binary.BigEndian.Uint16(b[id:]) } -// Protocol returns the value of the protocol field of the ipv4 header. +// Protocol returns the value of the protocol field of the IPv4 header. func (b IPv4) Protocol() uint8 { return b[protocol] } -// Flags returns the "flags" field of the ipv4 header. +// Flags returns the "flags" field of the IPv4 header. func (b IPv4) Flags() uint8 { return uint8(binary.BigEndian.Uint16(b[flagsFO:]) >> 13) } @@ -232,41 +254,52 @@ func (b IPv4) More() bool { return b.Flags()&IPv4FlagMoreFragments != 0 } -// TTL returns the "TTL" field of the ipv4 header. +// TTL returns the "TTL" field of the IPv4 header. func (b IPv4) TTL() uint8 { return b[ttl] } -// FragmentOffset returns the "fragment offset" field of the ipv4 header. +// FragmentOffset returns the "fragment offset" field of the IPv4 header. func (b IPv4) FragmentOffset() uint16 { return binary.BigEndian.Uint16(b[flagsFO:]) << 3 } -// TotalLength returns the "total length" field of the ipv4 header. +// TotalLength returns the "total length" field of the IPv4 header. func (b IPv4) TotalLength() uint16 { return binary.BigEndian.Uint16(b[IPv4TotalLenOffset:]) } -// Checksum returns the checksum field of the ipv4 header. +// Checksum returns the checksum field of the IPv4 header. func (b IPv4) Checksum() uint16 { return binary.BigEndian.Uint16(b[checksum:]) } -// SourceAddress returns the "source address" field of the ipv4 header. +// SourceAddress returns the "source address" field of the IPv4 header. func (b IPv4) SourceAddress() tcpip.Address { return tcpip.Address(b[srcAddr : srcAddr+IPv4AddressSize]) } -// DestinationAddress returns the "destination address" field of the ipv4 +// DestinationAddress returns the "destination address" field of the IPv4 // header. func (b IPv4) DestinationAddress() tcpip.Address { return tcpip.Address(b[dstAddr : dstAddr+IPv4AddressSize]) } -// Options returns a a buffer holding the options. -func (b IPv4) Options() []byte { +// 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 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() - return b[options:hdrLen:hdrLen] + return IPv4Options(b[options:hdrLen:hdrLen]) } // TransportProtocol implements Network.TransportProtocol. @@ -279,17 +312,17 @@ func (b IPv4) Payload() []byte { return b[b.HeaderLength():][:b.PayloadLength()] } -// PayloadLength returns the length of the payload portion of the ipv4 packet. +// PayloadLength returns the length of the payload portion of the IPv4 packet. func (b IPv4) PayloadLength() uint16 { return b.TotalLength() - uint16(b.HeaderLength()) } -// TOS returns the "type of service" field of the ipv4 header. +// TOS returns the "type of service" field of the IPv4 header. func (b IPv4) TOS() (uint8, uint32) { return b[tos], 0 } -// SetTOS sets the "type of service" field of the ipv4 header. +// SetTOS sets the "type of service" field of the IPv4 header. func (b IPv4) SetTOS(v uint8, _ uint32) { b[tos] = v } @@ -299,18 +332,18 @@ func (b IPv4) SetTTL(v byte) { b[ttl] = v } -// SetTotalLength sets the "total length" field of the ipv4 header. +// SetTotalLength sets the "total length" field of the IPv4 header. func (b IPv4) SetTotalLength(totalLength uint16) { binary.BigEndian.PutUint16(b[IPv4TotalLenOffset:], totalLength) } -// SetChecksum sets the checksum field of the ipv4 header. +// SetChecksum sets the checksum field of the IPv4 header. func (b IPv4) SetChecksum(v uint16) { binary.BigEndian.PutUint16(b[checksum:], v) } // SetFlagsFragmentOffset sets the "flags" and "fragment offset" fields of the -// ipv4 header. +// IPv4 header. func (b IPv4) SetFlagsFragmentOffset(flags uint8, offset uint16) { v := (uint16(flags) << 13) | (offset >> 3) binary.BigEndian.PutUint16(b[flagsFO:], v) @@ -321,25 +354,36 @@ func (b IPv4) SetID(v uint16) { binary.BigEndian.PutUint16(b[id:], v) } -// SetSourceAddress sets the "source address" field of the ipv4 header. +// SetSourceAddress sets the "source address" field of the IPv4 header. func (b IPv4) SetSourceAddress(addr tcpip.Address) { copy(b[srcAddr:srcAddr+IPv4AddressSize], addr) } -// SetDestinationAddress sets the "destination address" field of the ipv4 +// SetDestinationAddress sets the "destination address" field of the IPv4 // header. func (b IPv4) SetDestinationAddress(addr tcpip.Address) { copy(b[dstAddr:dstAddr+IPv4AddressSize], addr) } -// CalculateChecksum calculates the checksum of the ipv4 header. +// CalculateChecksum calculates the checksum of the IPv4 header. func (b IPv4) CalculateChecksum() uint16 { return Checksum(b[:b.HeaderLength()], 0) } -// Encode encodes all the fields of the ipv4 header. +// Encode encodes all the fields of the IPv4 header. func (b IPv4) Encode(i *IPv4Fields) { - b.SetHeaderLength(i.IHL) + // 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 serializer out of the fast + // path. + hdrLen := uint8(IPv4MinimumSize) + if len(i.Options) != 0 { + hdrLen += i.Options.Serialize(b[options:]) + } + 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) @@ -351,7 +395,7 @@ func (b IPv4) Encode(i *IPv4Fields) { copy(b[dstAddr:dstAddr+IPv4AddressSize], i.DstAddr) } -// EncodePartial updates the total length and checksum fields of ipv4 header, +// EncodePartial updates the total length and checksum fields of IPv4 header, // taking in the partial checksum, which is the checksum of the header without // the total length and checksum fields. It is useful in cases when similar // packets are produced. @@ -398,3 +442,587 @@ func IsV4LoopbackAddress(addr tcpip.Address) bool { } return addr[0] == 0x7f } + +// ========================= Options ========================== + +// An IPv4OptionType can hold the valuse for the Type in an IPv4 option. +type IPv4OptionType byte + +// These constants are needed to identify individual options in the option list. +// While RFC 791 (page 31) says "Every internet module must be able to act on +// every option." This has not generally been adhered to and some options have +// very low rates of support. We do not support options other than those shown +// below. + +const ( + // IPv4OptionListEndType is the option type for the End Of Option List + // option. Anything following is ignored. + IPv4OptionListEndType IPv4OptionType = 0 + + // IPv4OptionNOPType is the No-Operation option. May appear between other + // 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 + + // IPv4OptionTimestampType is the option type for the Timestamp option. + IPv4OptionTimestampType IPv4OptionType = 68 + + // ipv4OptionTypeOffset is the offset in an option of its type field. + ipv4OptionTypeOffset = 0 + + // IPv4OptionLengthOffset is the offset in an option of its length field. + IPv4OptionLengthOffset = 1 +) + +// Potential errors when parsing generic IP options. +var ( + ErrIPv4OptZeroLength = errors.New("zero length IP option") + ErrIPv4OptDuplicate = errors.New("duplicate IP option") + ErrIPv4OptInvalid = errors.New("invalid IP option") + ErrIPv4OptMalformed = errors.New("malformed IP option") + ErrIPv4OptionTruncated = errors.New("truncated IP option") + ErrIPv4OptionAddress = errors.New("bad IP option address") +) + +// IPv4Option is an interface representing various option types. +type IPv4Option interface { + // Type returns the type identifier of the option. + Type() IPv4OptionType + + // Size returns the size of the option in bytes. + Size() uint8 + + // Contents returns a slice holding the contents of the option. + Contents() []byte +} + +var _ IPv4Option = (*IPv4OptionGeneric)(nil) + +// IPv4OptionGeneric is an IPv4 Option of unknown type. +type IPv4OptionGeneric []byte + +// Type implements IPv4Option. +func (o *IPv4OptionGeneric) Type() IPv4OptionType { + return IPv4OptionType((*o)[ipv4OptionTypeOffset]) +} + +// Size implements IPv4Option. +func (o *IPv4OptionGeneric) Size() uint8 { return uint8(len(*o)) } + +// Contents implements IPv4Option. +func (o *IPv4OptionGeneric) Contents() []byte { return []byte(*o) } + +// IPv4OptionIterator is an iterator pointing to a specific IP option +// at any point of time. It also holds information as to a new options buffer +// that we are building up to hand back to the caller. +type IPv4OptionIterator struct { + options IPv4Options + // ErrCursor is where we are while parsing options. It is exported as any + // resulting ICMP packet is supposed to have a pointer to the byte within + // the IP packet where the error was detected. + ErrCursor uint8 + nextErrCursor uint8 + newOptions [IPv4MaximumOptionsSize]byte + writePoint int +} + +// MakeIterator sets up and returns an iterator of options. It also sets up the +// building of a new option set. +func (o IPv4Options) MakeIterator() IPv4OptionIterator { + return IPv4OptionIterator{ + options: o, + nextErrCursor: IPv4MinimumSize, + } +} + +// RemainingBuffer returns the remaining (unused) part of the new option buffer, +// into which a new option may be written. +func (i *IPv4OptionIterator) RemainingBuffer() IPv4Options { + return IPv4Options(i.newOptions[i.writePoint:]) +} + +// ConsumeBuffer marks a portion of the new buffer as used. +func (i *IPv4OptionIterator) ConsumeBuffer(size int) { + i.writePoint += size +} + +// PushNOPOrEnd puts one of the single byte options onto the new options. +// Only values 0 or 1 (ListEnd or NOP) are valid input. +func (i *IPv4OptionIterator) PushNOPOrEnd(val IPv4OptionType) { + if val > IPv4OptionNOPType { + panic(fmt.Sprintf("invalid option type %d pushed onto option build buffer", val)) + } + i.newOptions[i.writePoint] = byte(val) + i.writePoint++ +} + +// Finalize returns the completed replacement options buffer padded +// as needed. +func (i *IPv4OptionIterator) Finalize() IPv4Options { + // RFC 791 page 31 says: + // The options might not end on a 32-bit boundary. The internet header + // must be filled out with octets of zeros. The first of these would + // be interpreted as the end-of-options option, and the remainder as + // internet header padding. + // Since the buffer is already zero filled we just need to step the write + // pointer up to the next multiple of 4. + options := IPv4Options(i.newOptions[:(i.writePoint+0x3) & ^0x3]) + // Poison the write pointer. + i.writePoint = len(i.newOptions) + return options +} + +// Next returns the next IP option in the buffer/list of IP options. +// It returns +// - A slice of bytes holding the next option or nil if there is error. +// - A boolean which is true if parsing of all the options is complete. +// - An error which is non-nil if an error condition was encountered. +func (i *IPv4OptionIterator) Next() (IPv4Option, bool, error) { + // The opts slice gets shorter as we process the options. When we have no + // bytes left we are done. + if len(i.options) == 0 { + return nil, true, nil + } + + i.ErrCursor = i.nextErrCursor + + optType := IPv4OptionType(i.options[ipv4OptionTypeOffset]) + + if optType == IPv4OptionNOPType || optType == IPv4OptionListEndType { + optionBody := i.options[:1] + i.options = i.options[1:] + i.nextErrCursor = i.ErrCursor + 1 + retval := IPv4OptionGeneric(optionBody) + return &retval, false, nil + } + + // There are no more single byte options defined. All the rest have a length + // field so we need to sanity check it. + if len(i.options) == 1 { + return nil, true, ErrIPv4OptMalformed + } + + optLen := i.options[IPv4OptionLengthOffset] + + if optLen == 0 { + i.ErrCursor++ + return nil, true, ErrIPv4OptZeroLength + } + + if optLen == 1 { + i.ErrCursor++ + return nil, true, ErrIPv4OptMalformed + } + + if optLen > uint8(len(i.options)) { + i.ErrCursor++ + return nil, true, ErrIPv4OptionTruncated + } + + optionBody := i.options[:optLen] + i.nextErrCursor = i.ErrCursor + optLen + i.options = i.options[optLen:] + + // Check the length of some option types that we know. + switch optType { + case IPv4OptionTimestampType: + if optLen < IPv4OptionTimestampHdrLength { + i.ErrCursor++ + return nil, true, ErrIPv4OptMalformed + } + retval := IPv4OptionTimestamp(optionBody) + return &retval, false, nil + + case IPv4OptionRecordRouteType: + if optLen < IPv4OptionRecordRouteHdrLength { + i.ErrCursor++ + return nil, true, ErrIPv4OptMalformed + } + retval := IPv4OptionRecordRoute(optionBody) + return &retval, false, nil + } + retval := IPv4OptionGeneric(optionBody) + return &retval, false, nil +} + +// +// IP Timestamp option - RFC 791 page 22. +// +--------+--------+--------+--------+ +// |01000100| length | pointer|oflw|flg| +// +--------+--------+--------+--------+ +// | internet address | +// +--------+--------+--------+--------+ +// | timestamp | +// +--------+--------+--------+--------+ +// | ... | +// +// Type = 68 +// +// The Option Length is the number of octets in the option counting +// the type, length, pointer, and overflow/flag octets (maximum +// length 40). +// +// The Pointer is the number of octets from the beginning of this +// option to the end of timestamps plus one (i.e., it points to the +// octet beginning the space for next timestamp). The smallest +// legal value is 5. The timestamp area is full when the pointer +// is greater than the length. +// +// The Overflow (oflw) [4 bits] is the number of IP modules that +// cannot register timestamps due to lack of space. +// +// The Flag (flg) [4 bits] values are +// +// 0 -- time stamps only, stored in consecutive 32-bit words, +// +// 1 -- each timestamp is preceded with internet address of the +// registering entity, +// +// 3 -- the internet address fields are prespecified. An IP +// module only registers its timestamp if it matches its own +// address with the next specified internet address. +// +// Timestamps are defined in RFC 791 page 22 as milliseconds since midnight UTC. +// +// The Timestamp is a right-justified, 32-bit timestamp in +// milliseconds since midnight UT. If the time is not available in +// milliseconds or cannot be provided with respect to midnight UT +// then any time may be inserted as a timestamp provided the high +// order bit of the timestamp field is set to one to indicate the +// use of a non-standard value. + +// IPv4OptTSFlags sefines the values expected in the Timestamp +// option Flags field. +type IPv4OptTSFlags uint8 + +// +// Timestamp option specific related constants. +const ( + // IPv4OptionTimestampHdrLength is the length of the timestamp option header. + IPv4OptionTimestampHdrLength = 4 + + // IPv4OptionTimestampSize is the size of an IP timestamp. + IPv4OptionTimestampSize = 4 + + // IPv4OptionTimestampWithAddrSize is the size of an IP timestamp + Address. + IPv4OptionTimestampWithAddrSize = IPv4AddressSize + IPv4OptionTimestampSize + + // IPv4OptionTimestampMaxSize is limited by space for options + IPv4OptionTimestampMaxSize = IPv4MaximumOptionsSize + + // IPv4OptionTimestampOnlyFlag is a flag indicating that only timestamp + // is present. + IPv4OptionTimestampOnlyFlag IPv4OptTSFlags = 0 + + // IPv4OptionTimestampWithIPFlag is a flag indicating that both timestamps and + // IP are present. + IPv4OptionTimestampWithIPFlag IPv4OptTSFlags = 1 + + // IPv4OptionTimestampWithPredefinedIPFlag is a flag indicating that + // predefined IP is present. + IPv4OptionTimestampWithPredefinedIPFlag IPv4OptTSFlags = 3 +) + +// ipv4TimestampTime provides the current time as specified in RFC 791. +func ipv4TimestampTime(clock tcpip.Clock) uint32 { + const millisecondsPerDay = 24 * 3600 * 1000 + const nanoPerMilli = 1000000 + return uint32((clock.NowNanoseconds() / nanoPerMilli) % millisecondsPerDay) +} + +// IP Timestamp option fields. +const ( + // IPv4OptTSPointerOffset is the offset of the Timestamp pointer field. + IPv4OptTSPointerOffset = 2 + + // IPv4OptTSPointerOffset is the offset of the combined Flag and Overflow + // fields, (each being 4 bits). + IPv4OptTSOFLWAndFLGOffset = 3 + // These constants define the sub byte fields of the Flag and OverFlow field. + ipv4OptionTimestampOverflowshift = 4 + ipv4OptionTimestampFlagsMask byte = 0x0f +) + +var _ IPv4Option = (*IPv4OptionTimestamp)(nil) + +// IPv4OptionTimestamp is a Timestamp option from RFC 791. +type IPv4OptionTimestamp []byte + +// Type implements IPv4Option.Type(). +func (ts *IPv4OptionTimestamp) Type() IPv4OptionType { return IPv4OptionTimestampType } + +// Size implements IPv4Option. +func (ts *IPv4OptionTimestamp) Size() uint8 { return uint8(len(*ts)) } + +// Contents implements IPv4Option. +func (ts *IPv4OptionTimestamp) Contents() []byte { return []byte(*ts) } + +// Pointer returns the pointer field in the IP Timestamp option. +func (ts *IPv4OptionTimestamp) Pointer() uint8 { + return (*ts)[IPv4OptTSPointerOffset] +} + +// Flags returns the flags field in the IP Timestamp option. +func (ts *IPv4OptionTimestamp) Flags() IPv4OptTSFlags { + return IPv4OptTSFlags((*ts)[IPv4OptTSOFLWAndFLGOffset] & ipv4OptionTimestampFlagsMask) +} + +// Overflow returns the Overflow field in the IP Timestamp option. +func (ts *IPv4OptionTimestamp) Overflow() uint8 { + return (*ts)[IPv4OptTSOFLWAndFLGOffset] >> ipv4OptionTimestampOverflowshift +} + +// IncOverflow increments the Overflow field in the IP Timestamp option. It +// returns the incremented value. If the return value is 0 then the field +// overflowed. +func (ts *IPv4OptionTimestamp) IncOverflow() uint8 { + (*ts)[IPv4OptTSOFLWAndFLGOffset] += 1 << ipv4OptionTimestampOverflowshift + return ts.Overflow() +} + +// UpdateTimestamp updates the fields of the next free timestamp slot. +func (ts *IPv4OptionTimestamp) UpdateTimestamp(addr tcpip.Address, clock tcpip.Clock) { + slot := (*ts)[ts.Pointer()-1:] + + switch ts.Flags() { + case IPv4OptionTimestampOnlyFlag: + binary.BigEndian.PutUint32(slot, ipv4TimestampTime(clock)) + (*ts)[IPv4OptTSPointerOffset] += IPv4OptionTimestampSize + case IPv4OptionTimestampWithIPFlag: + if n := copy(slot, addr); n != IPv4AddressSize { + panic(fmt.Sprintf("copied %d bytes, expected %d bytes", n, IPv4AddressSize)) + } + binary.BigEndian.PutUint32(slot[IPv4AddressSize:], ipv4TimestampTime(clock)) + (*ts)[IPv4OptTSPointerOffset] += IPv4OptionTimestampWithAddrSize + case IPv4OptionTimestampWithPredefinedIPFlag: + if tcpip.Address(slot[:IPv4AddressSize]) == addr { + binary.BigEndian.PutUint32(slot[IPv4AddressSize:], ipv4TimestampTime(clock)) + (*ts)[IPv4OptTSPointerOffset] += IPv4OptionTimestampWithAddrSize + } + } +} + +// RecordRoute option specific related constants. +// +// from RFC 791 page 20: +// Record Route +// +// +--------+--------+--------+---------//--------+ +// |00000111| length | pointer| route data | +// +--------+--------+--------+---------//--------+ +// Type=7 +// +// The record route option provides a means to record the route of +// an internet datagram. +// +// The option begins with the option type code. The second octet +// is the option length which includes the option type code and the +// length octet, the pointer octet, and length-3 octets of route +// data. The third octet is the pointer into the route data +// indicating the octet which begins the next area to store a route +// address. The pointer is relative to this option, and the +// smallest legal value for the pointer is 4. +const ( + // IPv4OptionRecordRouteHdrLength is the length of the Record Route option + // header. + IPv4OptionRecordRouteHdrLength = 3 + + // IPv4OptRRPointerOffset is the offset to the pointer field in an RR + // option, which points to the next free slot in the list of addresses. + IPv4OptRRPointerOffset = 2 +) + +var _ IPv4Option = (*IPv4OptionRecordRoute)(nil) + +// IPv4OptionRecordRoute is an IPv4 RecordRoute option defined by RFC 791. +type IPv4OptionRecordRoute []byte + +// Pointer returns the pointer field in the IP RecordRoute option. +func (rr *IPv4OptionRecordRoute) Pointer() uint8 { + return (*rr)[IPv4OptRRPointerOffset] +} + +// StoreAddress stores the given IPv4 address into the next free slot. +func (rr *IPv4OptionRecordRoute) StoreAddress(addr tcpip.Address) { + start := rr.Pointer() - 1 // A one based number. + // start and room checked by caller. + if n := copy((*rr)[start:], addr); n != IPv4AddressSize { + panic(fmt.Sprintf("copied %d bytes, expected %d bytes", n, IPv4AddressSize)) + } + (*rr)[IPv4OptRRPointerOffset] += IPv4AddressSize +} + +// Type implements IPv4Option. +func (rr *IPv4OptionRecordRoute) Type() IPv4OptionType { return IPv4OptionRecordRouteType } + +// Size implements IPv4Option. +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/ipv4_test.go b/pkg/tcpip/header/ipv4_test.go new file mode 100644 index 000000000..6475cd694 --- /dev/null +++ b/pkg/tcpip/header/ipv4_test.go @@ -0,0 +1,179 @@ +// 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 header_test + +import ( + "testing" + + "github.com/google/go-cmp/cmp" + "gvisor.dev/gvisor/pkg/tcpip/buffer" + "gvisor.dev/gvisor/pkg/tcpip/header" +) + +func TestIPv4OptionsSerializer(t *testing.T) { + optCases := []struct { + name string + option []header.IPv4SerializableOption + expect []byte + }{ + { + name: "NOP", + option: []header.IPv4SerializableOption{ + &header.IPv4SerializableNOPOption{}, + }, + expect: []byte{1, 0, 0, 0}, + }, + { + name: "ListEnd", + option: []header.IPv4SerializableOption{ + &header.IPv4SerializableListEndOption{}, + }, + expect: []byte{0, 0, 0, 0}, + }, + { + name: "RouterAlert", + option: []header.IPv4SerializableOption{ + &header.IPv4SerializableRouterAlertOption{}, + }, + expect: []byte{148, 4, 0, 0}, + }, { + name: "NOP and RouterAlert", + option: []header.IPv4SerializableOption{ + &header.IPv4SerializableNOPOption{}, + &header.IPv4SerializableRouterAlertOption{}, + }, + expect: []byte{1, 148, 4, 0, 0, 0, 0, 0}, + }, + } + + for _, opt := range optCases { + t.Run(opt.name, func(t *testing.T) { + s := header.IPv4OptionsSerializer(opt.option) + l := s.Length() + if got := len(opt.expect); got != int(l) { + t.Fatalf("s.Length() = %d, want = %d", got, l) + } + b := make([]byte, l) + for i := range b { + // Fill the buffer with full bytes to ensure padding is being set + // correctly. + b[i] = 0xFF + } + if serializedLength := s.Serialize(b); serializedLength != l { + t.Fatalf("s.Serialize(_) = %d, want %d", serializedLength, l) + } + if diff := cmp.Diff(opt.expect, b); diff != "" { + t.Errorf("mismatched serialized option (-want +got):\n%s", diff) + } + }) + } +} + +// TestIPv4Encode checks that ipv4.Encode correctly fills out the requested +// fields when options are supplied. +func TestIPv4EncodeOptions(t *testing.T) { + tests := []struct { + name string + numberOfNops int + encodedOptions header.IPv4Options // reply should look like this + wantIHL int + }{ + { + name: "valid no options", + wantIHL: header.IPv4MinimumSize, + }, + { + name: "one byte options", + numberOfNops: 1, + encodedOptions: header.IPv4Options{1, 0, 0, 0}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "two byte options", + numberOfNops: 2, + encodedOptions: header.IPv4Options{1, 1, 0, 0}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "three byte options", + numberOfNops: 3, + encodedOptions: header.IPv4Options{1, 1, 1, 0}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "four byte options", + numberOfNops: 4, + encodedOptions: header.IPv4Options{1, 1, 1, 1}, + wantIHL: header.IPv4MinimumSize + 4, + }, + { + name: "five byte options", + numberOfNops: 5, + encodedOptions: header.IPv4Options{1, 1, 1, 1, 1, 0, 0, 0}, + wantIHL: header.IPv4MinimumSize + 8, + }, + { + name: "thirty nine byte options", + numberOfNops: 39, + encodedOptions: header.IPv4Options{ + 1, 1, 1, 1, 1, 1, 1, 1, + 1, 1, 1, 1, 1, 1, 1, 1, + 1, 1, 1, 1, 1, 1, 1, 1, + 1, 1, 1, 1, 1, 1, 1, 1, + 1, 1, 1, 1, 1, 1, 1, 0, + }, + wantIHL: header.IPv4MinimumSize + 40, + }, + } + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + serializeOpts := header.IPv4OptionsSerializer(make([]header.IPv4SerializableOption, test.numberOfNops)) + for i := range serializeOpts { + serializeOpts[i] = &header.IPv4SerializableNOPOption{} + } + paddedOptionLength := serializeOpts.Length() + ipHeaderLength := int(header.IPv4MinimumSize + paddedOptionLength) + if ipHeaderLength > header.IPv4MaximumHeaderSize { + t.Fatalf("IP header length too large: got = %d, want <= %d ", ipHeaderLength, header.IPv4MaximumHeaderSize) + } + totalLen := uint16(ipHeaderLength) + hdr := buffer.NewPrependable(int(totalLen)) + ip := header.IPv4(hdr.Prepend(ipHeaderLength)) + // To check the padding works, poison the last byte of the options space. + if paddedOptionLength != serializeOpts.Length() { + ip.SetHeaderLength(uint8(ipHeaderLength)) + ip.Options()[paddedOptionLength-1] = 0xff + ip.SetHeaderLength(0) + } + ip.Encode(&header.IPv4Fields{ + Options: serializeOpts, + }) + options := ip.Options() + wantOptions := test.encodedOptions + if got, want := int(ip.HeaderLength()), test.wantIHL; got != want { + t.Errorf("got IHL of %d, want %d", got, want) + } + + // cmp.Diff does not consider nil slices equal to empty slices, but we do. + if len(wantOptions) == 0 && len(options) == 0 { + return + } + + if diff := cmp.Diff(wantOptions, options); diff != "" { + t.Errorf("options mismatch (-want +got):\n%s", diff) + } + }) + } +} diff --git a/pkg/tcpip/header/ipv6.go b/pkg/tcpip/header/ipv6.go index c5d8a3456..d522e5f10 100644 --- a/pkg/tcpip/header/ipv6.go +++ b/pkg/tcpip/header/ipv6.go @@ -48,13 +48,15 @@ type IPv6Fields struct { // FlowLabel is the "flow label" field of an IPv6 packet. FlowLabel uint32 - // PayloadLength is the "payload length" field of an IPv6 packet. + // PayloadLength is the "payload length" field of an IPv6 packet, including + // the length of all extension headers. PayloadLength uint16 - // NextHeader is the "next header" field of an IPv6 packet. - NextHeader uint8 + // TransportProtocol is the transport layer protocol number. Serialized in the + // last "next header" field of the IPv6 header + extension headers. + TransportProtocol tcpip.TransportProtocolNumber - // HopLimit is the "hop limit" field of an IPv6 packet. + // HopLimit is the "Hop Limit" field of an IPv6 packet. HopLimit uint8 // SrcAddr is the "source ip address" of an IPv6 packet. @@ -62,6 +64,9 @@ type IPv6Fields struct { // DstAddr is the "destination ip address" of an IPv6 packet. DstAddr tcpip.Address + + // ExtensionHeaders are the extension headers following the IPv6 header. + ExtensionHeaders IPv6ExtHdrSerializer } // IPv6 represents an ipv6 header stored in a byte array. @@ -101,8 +106,10 @@ const ( // The address is ff02::2. IPv6AllRoutersMulticastAddress tcpip.Address = "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02" - // IPv6MinimumMTU is the minimum MTU required by IPv6, per RFC 2460, - // section 5. + // IPv6MinimumMTU is the minimum MTU required by IPv6, per RFC 8200, + // section 5: + // IPv6 requires that every link in the Internet have an MTU of 1280 octets + // or greater. This is known as the IPv6 minimum link MTU. IPv6MinimumMTU = 1280 // IPv6Loopback is the IPv6 Loopback address. @@ -169,7 +176,7 @@ func (b IPv6) PayloadLength() uint16 { return binary.BigEndian.Uint16(b[IPv6PayloadLenOffset:]) } -// HopLimit returns the value of the "hop limit" field of the ipv6 header. +// HopLimit returns the value of the "Hop Limit" field of the ipv6 header. func (b IPv6) HopLimit() uint8 { return b[hopLimit] } @@ -234,6 +241,11 @@ func (b IPv6) SetDestinationAddress(addr tcpip.Address) { copy(b[v6DstAddr:][:IPv6AddressSize], addr) } +// SetHopLimit sets the value of the "Hop Limit" field. +func (b IPv6) SetHopLimit(v uint8) { + b[hopLimit] = v +} + // SetNextHeader sets the value of the "next header" field of the ipv6 header. func (b IPv6) SetNextHeader(v uint8) { b[IPv6NextHeaderOffset] = v @@ -246,12 +258,14 @@ func (IPv6) SetChecksum(uint16) { // Encode encodes all the fields of the ipv6 header. func (b IPv6) Encode(i *IPv6Fields) { + extHdr := b[IPv6MinimumSize:] b.SetTOS(i.TrafficClass, i.FlowLabel) b.SetPayloadLength(i.PayloadLength) - b[IPv6NextHeaderOffset] = i.NextHeader b[hopLimit] = i.HopLimit b.SetSourceAddress(i.SrcAddr) b.SetDestinationAddress(i.DstAddr) + nextHeader, _ := i.ExtensionHeaders.Serialize(i.TransportProtocol, extHdr) + b[IPv6NextHeaderOffset] = nextHeader } // IsValid performs basic validation on the packet. @@ -373,6 +387,12 @@ func IsV6LinkLocalAddress(addr tcpip.Address) bool { return addr[0] == 0xfe && (addr[1]&0xc0) == 0x80 } +// IsV6LoopbackAddress determines if the provided address is an IPv6 loopback +// address. +func IsV6LoopbackAddress(addr tcpip.Address) bool { + return addr == IPv6Loopback +} + // IsV6LinkLocalMulticastAddress determines if the provided address is an IPv6 // link-local multicast address. func IsV6LinkLocalMulticastAddress(addr tcpip.Address) bool { diff --git a/pkg/tcpip/header/ipv6_extension_headers.go b/pkg/tcpip/header/ipv6_extension_headers.go index 583c2c5d3..1fbb2cc98 100644 --- a/pkg/tcpip/header/ipv6_extension_headers.go +++ b/pkg/tcpip/header/ipv6_extension_headers.go @@ -20,7 +20,9 @@ import ( "encoding/binary" "fmt" "io" + "math" + "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" ) @@ -47,6 +49,11 @@ const ( // IPv6NoNextHeaderIdentifier is the header identifier used to signify the end // of an IPv6 payload, as per RFC 8200 section 4.7. IPv6NoNextHeaderIdentifier IPv6ExtensionHeaderIdentifier = 59 + + // IPv6UnknownExtHdrIdentifier is reserved by IANA. + // https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#extension-header + // "254 Use for experimentation and testing [RFC3692][RFC4727]" + IPv6UnknownExtHdrIdentifier IPv6ExtensionHeaderIdentifier = 254 ) const ( @@ -70,8 +77,8 @@ const ( // Fragment Offset field within an IPv6FragmentExtHdr. ipv6FragmentExtHdrFragmentOffsetOffset = 0 - // ipv6FragmentExtHdrFragmentOffsetShift is the least significant bits to - // discard from the Fragment Offset. + // ipv6FragmentExtHdrFragmentOffsetShift is the bit offset of the Fragment + // Offset field within an IPv6FragmentExtHdr. ipv6FragmentExtHdrFragmentOffsetShift = 3 // ipv6FragmentExtHdrFlagsIdx is the index to the flags field within an @@ -109,6 +116,37 @@ const ( IPv6FragmentExtHdrFragmentOffsetBytesPerUnit = 8 ) +// padIPv6OptionsLength returns the total length for IPv6 options of length l +// considering the 8-octet alignment as stated in RFC 8200 Section 4.2. +func padIPv6OptionsLength(length int) int { + return (length + ipv6ExtHdrLenBytesPerUnit - 1) & ^(ipv6ExtHdrLenBytesPerUnit - 1) +} + +// padIPv6Option fills b with the appropriate padding options depending on its +// length. +func padIPv6Option(b []byte) { + switch len(b) { + case 0: // No padding needed. + case 1: // Pad with Pad1. + b[ipv6ExtHdrOptionTypeOffset] = uint8(ipv6Pad1ExtHdrOptionIdentifier) + default: // Pad with PadN. + s := b[ipv6ExtHdrOptionPayloadOffset:] + for i := range s { + s[i] = 0 + } + b[ipv6ExtHdrOptionTypeOffset] = uint8(ipv6PadNExtHdrOptionIdentifier) + b[ipv6ExtHdrOptionLengthOffset] = uint8(len(s)) + } +} + +// ipv6OptionsAlignmentPadding returns the number of padding bytes needed to +// serialize an option at headerOffset with alignment requirements +// [align]n + alignOffset. +func ipv6OptionsAlignmentPadding(headerOffset int, align int, alignOffset int) int { + padLen := headerOffset - alignOffset + return ((padLen + align - 1) & ^(align - 1)) - padLen +} + // IPv6PayloadHeader is implemented by the various headers that can be found // in an IPv6 payload. // @@ -201,29 +239,51 @@ type IPv6ExtHdrOption interface { isIPv6ExtHdrOption() } -// IPv6ExtHdrOptionIndentifier is an IPv6 extension header option identifier. -type IPv6ExtHdrOptionIndentifier uint8 +// IPv6ExtHdrOptionIdentifier is an IPv6 extension header option identifier. +type IPv6ExtHdrOptionIdentifier uint8 const ( // ipv6Pad1ExtHdrOptionIdentifier is the identifier for a padding option that // provides 1 byte padding, as outlined in RFC 8200 section 4.2. - ipv6Pad1ExtHdrOptionIdentifier IPv6ExtHdrOptionIndentifier = 0 + ipv6Pad1ExtHdrOptionIdentifier IPv6ExtHdrOptionIdentifier = 0 // ipv6PadBExtHdrOptionIdentifier is the identifier for a padding option that // provides variable length byte padding, as outlined in RFC 8200 section 4.2. - ipv6PadNExtHdrOptionIdentifier IPv6ExtHdrOptionIndentifier = 1 + ipv6PadNExtHdrOptionIdentifier IPv6ExtHdrOptionIdentifier = 1 + + // ipv6RouterAlertHopByHopOptionIdentifier is the identifier for the Router + // Alert Hop by Hop option as defined in RFC 2711 section 2.1. + ipv6RouterAlertHopByHopOptionIdentifier IPv6ExtHdrOptionIdentifier = 5 + + // ipv6ExtHdrOptionTypeOffset is the option type offset in an extension header + // option as defined in RFC 8200 section 4.2. + ipv6ExtHdrOptionTypeOffset = 0 + + // ipv6ExtHdrOptionLengthOffset is the option length offset in an extension + // header option as defined in RFC 8200 section 4.2. + ipv6ExtHdrOptionLengthOffset = 1 + + // ipv6ExtHdrOptionPayloadOffset is the option payload offset in an extension + // header option as defined in RFC 8200 section 4.2. + ipv6ExtHdrOptionPayloadOffset = 2 ) +// ipv6UnknownActionFromIdentifier maps an extension header option's +// identifier's high bits to the action to take when the identifier is unknown. +func ipv6UnknownActionFromIdentifier(id IPv6ExtHdrOptionIdentifier) IPv6OptionUnknownAction { + return IPv6OptionUnknownAction((id & ipv6UnknownExtHdrOptionActionMask) >> ipv6UnknownExtHdrOptionActionShift) +} + // IPv6UnknownExtHdrOption holds the identifier and data for an IPv6 extension // header option that is unknown by the parsing utilities. type IPv6UnknownExtHdrOption struct { - Identifier IPv6ExtHdrOptionIndentifier + Identifier IPv6ExtHdrOptionIdentifier Data []byte } // UnknownAction implements IPv6OptionUnknownAction.UnknownAction. func (o *IPv6UnknownExtHdrOption) UnknownAction() IPv6OptionUnknownAction { - return IPv6OptionUnknownAction((o.Identifier & ipv6UnknownExtHdrOptionActionMask) >> ipv6UnknownExtHdrOptionActionShift) + return ipv6UnknownActionFromIdentifier(o.Identifier) } // isIPv6ExtHdrOption implements IPv6ExtHdrOption.isIPv6ExtHdrOption. @@ -246,7 +306,7 @@ func (i *IPv6OptionsExtHdrOptionsIterator) Next() (IPv6ExtHdrOption, bool, error // options buffer has been exhausted and we are done iterating. return nil, true, nil } - id := IPv6ExtHdrOptionIndentifier(temp) + id := IPv6ExtHdrOptionIdentifier(temp) // If the option identifier indicates the option is a Pad1 option, then we // know the option does not have Length and Data fields. End processing of @@ -289,6 +349,14 @@ func (i *IPv6OptionsExtHdrOptionsIterator) Next() (IPv6ExtHdrOption, bool, error panic(fmt.Sprintf("error when skipping PadN (N = %d) option's data bytes: %s", length, err)) } continue + case ipv6RouterAlertHopByHopOptionIdentifier: + var routerAlertValue [ipv6RouterAlertPayloadLength]byte + if n, err := i.reader.Read(routerAlertValue[:]); err != nil { + panic(fmt.Sprintf("error when reading RouterAlert option's data bytes: %s", err)) + } else if n != ipv6RouterAlertPayloadLength { + return nil, true, fmt.Errorf("read %d bytes for RouterAlert option, expected %d", n, ipv6RouterAlertPayloadLength) + } + return &IPv6RouterAlertOption{Value: IPv6RouterAlertValue(binary.BigEndian.Uint16(routerAlertValue[:]))}, false, nil default: bytes := make([]byte, length) if n, err := io.ReadFull(&i.reader, bytes); err != nil { @@ -452,9 +520,11 @@ func (i *IPv6PayloadIterator) AsRawHeader(consume bool) IPv6RawPayloadHeader { // Since we consume the iterator, we return the payload as is. buf = i.payload - // Mark i as done. + // Mark i as done, but keep track of where we were for error reporting. *i = IPv6PayloadIterator{ nextHdrIdentifier: IPv6NoNextHeaderIdentifier, + headerOffset: i.headerOffset, + nextOffset: i.nextOffset, } } else { buf = i.payload.Clone(nil) @@ -602,3 +672,248 @@ func (i *IPv6PayloadIterator) nextHeaderData(fragmentHdr bool, bytes []byte) (IP return IPv6ExtensionHeaderIdentifier(nextHdrIdentifier), bytes, nil } + +// IPv6SerializableExtHdr provides serialization for IPv6 extension +// headers. +type IPv6SerializableExtHdr interface { + // identifier returns the assigned IPv6 header identifier for this extension + // header. + identifier() IPv6ExtensionHeaderIdentifier + + // length returns the total serialized length in bytes of this extension + // header, including the common next header and length fields. + length() int + + // serializeInto serializes the receiver into the provided byte + // buffer and with the provided nextHeader value. + // + // 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 MAY panic if the provided byte + // buffer is not of sufficient size. + // + // serializeInto returns 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(nextHeader uint8, b []byte) int +} + +var _ IPv6SerializableExtHdr = (*IPv6SerializableHopByHopExtHdr)(nil) + +// IPv6SerializableHopByHopExtHdr implements serialization of the Hop by Hop +// options extension header. +type IPv6SerializableHopByHopExtHdr []IPv6SerializableHopByHopOption + +const ( + // ipv6HopByHopExtHdrNextHeaderOffset is the offset of the next header field + // in a hop by hop extension header as defined in RFC 8200 section 4.3. + ipv6HopByHopExtHdrNextHeaderOffset = 0 + + // ipv6HopByHopExtHdrLengthOffset is the offset of the length field in a hop + // by hop extension header as defined in RFC 8200 section 4.3. + ipv6HopByHopExtHdrLengthOffset = 1 + + // ipv6HopByHopExtHdrPayloadOffset is the offset of the options in a hop by + // hop extension header as defined in RFC 8200 section 4.3. + ipv6HopByHopExtHdrOptionsOffset = 2 + + // ipv6HopByHopExtHdrUnaccountedLenWords is the implicit number of 8-octet + // words in a hop by hop extension header's length field, as stated in RFC + // 8200 section 4.3: + // Length of the Hop-by-Hop Options header in 8-octet units, + // not including the first 8 octets. + ipv6HopByHopExtHdrUnaccountedLenWords = 1 +) + +// identifier implements IPv6SerializableExtHdr. +func (IPv6SerializableHopByHopExtHdr) identifier() IPv6ExtensionHeaderIdentifier { + return IPv6HopByHopOptionsExtHdrIdentifier +} + +// length implements IPv6SerializableExtHdr. +func (h IPv6SerializableHopByHopExtHdr) length() int { + var total int + for _, opt := range h { + align, alignOffset := opt.alignment() + total += ipv6OptionsAlignmentPadding(total, align, alignOffset) + total += ipv6ExtHdrOptionPayloadOffset + int(opt.length()) + } + // Account for next header and total length fields and add padding. + return padIPv6OptionsLength(ipv6HopByHopExtHdrOptionsOffset + total) +} + +// serializeInto implements IPv6SerializableExtHdr. +func (h IPv6SerializableHopByHopExtHdr) serializeInto(nextHeader uint8, b []byte) int { + optBuffer := b[ipv6HopByHopExtHdrOptionsOffset:] + totalLength := ipv6HopByHopExtHdrOptionsOffset + for _, opt := range h { + // Calculate alignment requirements and pad buffer if necessary. + align, alignOffset := opt.alignment() + padLen := ipv6OptionsAlignmentPadding(totalLength, align, alignOffset) + if padLen != 0 { + padIPv6Option(optBuffer[:padLen]) + totalLength += padLen + optBuffer = optBuffer[padLen:] + } + + l := opt.serializeInto(optBuffer[ipv6ExtHdrOptionPayloadOffset:]) + optBuffer[ipv6ExtHdrOptionTypeOffset] = uint8(opt.identifier()) + optBuffer[ipv6ExtHdrOptionLengthOffset] = l + l += ipv6ExtHdrOptionPayloadOffset + totalLength += int(l) + optBuffer = optBuffer[l:] + } + padded := padIPv6OptionsLength(totalLength) + if padded != totalLength { + padIPv6Option(optBuffer[:padded-totalLength]) + totalLength = padded + } + wordsLen := totalLength/ipv6ExtHdrLenBytesPerUnit - ipv6HopByHopExtHdrUnaccountedLenWords + if wordsLen > math.MaxUint8 { + panic(fmt.Sprintf("IPv6 hop by hop options too large: %d+1 64-bit words", wordsLen)) + } + b[ipv6HopByHopExtHdrNextHeaderOffset] = nextHeader + b[ipv6HopByHopExtHdrLengthOffset] = uint8(wordsLen) + return totalLength +} + +// IPv6SerializableHopByHopOption provides serialization for hop by hop options. +type IPv6SerializableHopByHopOption interface { + // identifier returns the option identifier of this Hop by Hop option. + identifier() IPv6ExtHdrOptionIdentifier + + // length returns the *payload* size of the option (not considering the type + // and length fields). + length() uint8 + + // alignment returns the alignment requirements from this option. + // + // Alignment requirements take the form [align]n + offset as specified in + // RFC 8200 section 4.2. The alignment requirement is on the offset between + // the option type byte and the start of the hop by hop header. + // + // align must be a power of 2. + alignment() (align int, offset int) + + // serializeInto serializes the receiver 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 MAY 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([]byte) uint8 +} + +var _ IPv6SerializableHopByHopOption = (*IPv6RouterAlertOption)(nil) + +// IPv6RouterAlertOption is the IPv6 Router alert Hop by Hop option defined in +// RFC 2711 section 2.1. +type IPv6RouterAlertOption struct { + Value IPv6RouterAlertValue +} + +// IPv6RouterAlertValue is the payload of an IPv6 Router Alert option. +type IPv6RouterAlertValue uint16 + +const ( + // IPv6RouterAlertMLD indicates a datagram containing a Multicast Listener + // Discovery message as defined in RFC 2711 section 2.1. + IPv6RouterAlertMLD IPv6RouterAlertValue = 0 + // IPv6RouterAlertRSVP indicates a datagram containing an RSVP message as + // defined in RFC 2711 section 2.1. + IPv6RouterAlertRSVP IPv6RouterAlertValue = 1 + // IPv6RouterAlertActiveNetworks indicates a datagram containing an Active + // Networks message as defined in RFC 2711 section 2.1. + IPv6RouterAlertActiveNetworks IPv6RouterAlertValue = 2 + + // ipv6RouterAlertPayloadLength is the length of the Router Alert payload + // as defined in RFC 2711. + ipv6RouterAlertPayloadLength = 2 + + // ipv6RouterAlertAlignmentRequirement is the alignment requirement for the + // Router Alert option defined as 2n+0 in RFC 2711. + ipv6RouterAlertAlignmentRequirement = 2 + + // ipv6RouterAlertAlignmentOffsetRequirement is the alignment offset + // requirement for the Router Alert option defined as 2n+0 in RFC 2711 section + // 2.1. + ipv6RouterAlertAlignmentOffsetRequirement = 0 +) + +// UnknownAction implements IPv6ExtHdrOption. +func (*IPv6RouterAlertOption) UnknownAction() IPv6OptionUnknownAction { + return ipv6UnknownActionFromIdentifier(ipv6RouterAlertHopByHopOptionIdentifier) +} + +// isIPv6ExtHdrOption implements IPv6ExtHdrOption. +func (*IPv6RouterAlertOption) isIPv6ExtHdrOption() {} + +// identifier implements IPv6SerializableHopByHopOption. +func (*IPv6RouterAlertOption) identifier() IPv6ExtHdrOptionIdentifier { + return ipv6RouterAlertHopByHopOptionIdentifier +} + +// length implements IPv6SerializableHopByHopOption. +func (*IPv6RouterAlertOption) length() uint8 { + return ipv6RouterAlertPayloadLength +} + +// alignment implements IPv6SerializableHopByHopOption. +func (*IPv6RouterAlertOption) alignment() (int, int) { + // From RFC 2711 section 2.1: + // Alignment requirement: 2n+0. + return ipv6RouterAlertAlignmentRequirement, ipv6RouterAlertAlignmentOffsetRequirement +} + +// serializeInto implements IPv6SerializableHopByHopOption. +func (o *IPv6RouterAlertOption) serializeInto(b []byte) uint8 { + binary.BigEndian.PutUint16(b, uint16(o.Value)) + return ipv6RouterAlertPayloadLength +} + +// IPv6ExtHdrSerializer provides serialization of IPv6 extension headers. +type IPv6ExtHdrSerializer []IPv6SerializableExtHdr + +// Serialize serializes the provided list of IPv6 extension headers into b. +// +// Note, b must be of sufficient size to hold all the headers in s. See +// IPv6ExtHdrSerializer.Length for details on the getting the total size of a +// serialized IPv6ExtHdrSerializer. +// +// Serialize may panic if b is not of sufficient size to hold all the options +// in s. +// +// Serialize takes the transportProtocol value to be used as the last extension +// header's Next Header value and returns the header identifier of the first +// serialized extension header and the total serialized length. +func (s IPv6ExtHdrSerializer) Serialize(transportProtocol tcpip.TransportProtocolNumber, b []byte) (uint8, int) { + nextHeader := uint8(transportProtocol) + if len(s) == 0 { + return nextHeader, 0 + } + var totalLength int + for i, h := range s[:len(s)-1] { + length := h.serializeInto(uint8(s[i+1].identifier()), b) + b = b[length:] + totalLength += length + } + totalLength += s[len(s)-1].serializeInto(nextHeader, b) + return uint8(s[0].identifier()), totalLength +} + +// Length returns the total number of bytes required to serialize the extension +// headers. +func (s IPv6ExtHdrSerializer) Length() int { + var totalLength int + for _, h := range s { + totalLength += h.length() + } + return totalLength +} diff --git a/pkg/tcpip/header/ipv6_extension_headers_test.go b/pkg/tcpip/header/ipv6_extension_headers_test.go index ab20c5f37..5d2296353 100644 --- a/pkg/tcpip/header/ipv6_extension_headers_test.go +++ b/pkg/tcpip/header/ipv6_extension_headers_test.go @@ -21,6 +21,7 @@ import ( "testing" "github.com/google/go-cmp/cmp" + "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" ) @@ -59,7 +60,7 @@ func (a IPv6DestinationOptionsExtHdr) Equal(b IPv6DestinationOptionsExtHdr) bool func TestIPv6UnknownExtHdrOption(t *testing.T) { tests := []struct { name string - identifier IPv6ExtHdrOptionIndentifier + identifier IPv6ExtHdrOptionIdentifier expectedUnknownAction IPv6OptionUnknownAction }{ { @@ -990,3 +991,331 @@ func TestIPv6ExtHdrIter(t *testing.T) { }) } } + +var _ IPv6SerializableHopByHopOption = (*dummyHbHOptionSerializer)(nil) + +// dummyHbHOptionSerializer provides a generic implementation of +// IPv6SerializableHopByHopOption for use in tests. +type dummyHbHOptionSerializer struct { + id IPv6ExtHdrOptionIdentifier + payload []byte + align int + alignOffset int +} + +// identifier implements IPv6SerializableHopByHopOption. +func (s *dummyHbHOptionSerializer) identifier() IPv6ExtHdrOptionIdentifier { + return s.id +} + +// length implements IPv6SerializableHopByHopOption. +func (s *dummyHbHOptionSerializer) length() uint8 { + return uint8(len(s.payload)) +} + +// alignment implements IPv6SerializableHopByHopOption. +func (s *dummyHbHOptionSerializer) alignment() (int, int) { + align := 1 + if s.align != 0 { + align = s.align + } + return align, s.alignOffset +} + +// serializeInto implements IPv6SerializableHopByHopOption. +func (s *dummyHbHOptionSerializer) serializeInto(b []byte) uint8 { + return uint8(copy(b, s.payload)) +} + +func TestIPv6HopByHopSerializer(t *testing.T) { + validateDummies := func(t *testing.T, serializable IPv6SerializableHopByHopOption, deserialized IPv6ExtHdrOption) { + t.Helper() + dummy, ok := serializable.(*dummyHbHOptionSerializer) + if !ok { + t.Fatalf("got serializable = %T, want = *dummyHbHOptionSerializer", serializable) + } + unknown, ok := deserialized.(*IPv6UnknownExtHdrOption) + if !ok { + t.Fatalf("got deserialized = %T, want = %T", deserialized, &IPv6UnknownExtHdrOption{}) + } + if dummy.id != unknown.Identifier { + t.Errorf("got deserialized identifier = %d, want = %d", unknown.Identifier, dummy.id) + } + if diff := cmp.Diff(dummy.payload, unknown.Data); diff != "" { + t.Errorf("option payload deserialization mismatch (-want +got):\n%s", diff) + } + } + tests := []struct { + name string + nextHeader uint8 + options []IPv6SerializableHopByHopOption + expect []byte + validate func(*testing.T, IPv6SerializableHopByHopOption, IPv6ExtHdrOption) + }{ + { + name: "single option", + nextHeader: 13, + options: []IPv6SerializableHopByHopOption{ + &dummyHbHOptionSerializer{ + id: 15, + payload: []byte{9, 8, 7, 6}, + }, + }, + expect: []byte{13, 0, 15, 4, 9, 8, 7, 6}, + validate: validateDummies, + }, + { + name: "short option padN zero", + nextHeader: 88, + options: []IPv6SerializableHopByHopOption{ + &dummyHbHOptionSerializer{ + id: 22, + payload: []byte{4, 5}, + }, + }, + expect: []byte{88, 0, 22, 2, 4, 5, 1, 0}, + validate: validateDummies, + }, + { + name: "short option pad1", + nextHeader: 11, + options: []IPv6SerializableHopByHopOption{ + &dummyHbHOptionSerializer{ + id: 33, + payload: []byte{1, 2, 3}, + }, + }, + expect: []byte{11, 0, 33, 3, 1, 2, 3, 0}, + validate: validateDummies, + }, + { + name: "long option padN", + nextHeader: 55, + options: []IPv6SerializableHopByHopOption{ + &dummyHbHOptionSerializer{ + id: 77, + payload: []byte{1, 2, 3, 4, 5, 6, 7, 8}, + }, + }, + expect: []byte{55, 1, 77, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 0, 0}, + validate: validateDummies, + }, + { + name: "two options", + nextHeader: 33, + options: []IPv6SerializableHopByHopOption{ + &dummyHbHOptionSerializer{ + id: 11, + payload: []byte{1, 2, 3}, + }, + &dummyHbHOptionSerializer{ + id: 22, + payload: []byte{4, 5, 6}, + }, + }, + expect: []byte{33, 1, 11, 3, 1, 2, 3, 22, 3, 4, 5, 6, 1, 2, 0, 0}, + validate: validateDummies, + }, + { + name: "two options align 2n", + nextHeader: 33, + options: []IPv6SerializableHopByHopOption{ + &dummyHbHOptionSerializer{ + id: 11, + payload: []byte{1, 2, 3}, + }, + &dummyHbHOptionSerializer{ + id: 22, + payload: []byte{4, 5, 6}, + align: 2, + }, + }, + expect: []byte{33, 1, 11, 3, 1, 2, 3, 0, 22, 3, 4, 5, 6, 1, 1, 0}, + validate: validateDummies, + }, + { + name: "two options align 8n+1", + nextHeader: 33, + options: []IPv6SerializableHopByHopOption{ + &dummyHbHOptionSerializer{ + id: 11, + payload: []byte{1, 2}, + }, + &dummyHbHOptionSerializer{ + id: 22, + payload: []byte{4, 5, 6}, + align: 8, + alignOffset: 1, + }, + }, + expect: []byte{33, 1, 11, 2, 1, 2, 1, 1, 0, 22, 3, 4, 5, 6, 1, 0}, + validate: validateDummies, + }, + { + name: "no options", + nextHeader: 33, + options: []IPv6SerializableHopByHopOption{}, + expect: []byte{33, 0, 1, 4, 0, 0, 0, 0}, + }, + { + name: "Router Alert", + nextHeader: 33, + options: []IPv6SerializableHopByHopOption{&IPv6RouterAlertOption{Value: IPv6RouterAlertMLD}}, + expect: []byte{33, 0, 5, 2, 0, 0, 1, 0}, + validate: func(t *testing.T, _ IPv6SerializableHopByHopOption, deserialized IPv6ExtHdrOption) { + t.Helper() + routerAlert, ok := deserialized.(*IPv6RouterAlertOption) + if !ok { + t.Fatalf("got deserialized = %T, want = *IPv6RouterAlertOption", deserialized) + } + if routerAlert.Value != IPv6RouterAlertMLD { + t.Errorf("got routerAlert.Value = %d, want = %d", routerAlert.Value, IPv6RouterAlertMLD) + } + }, + }, + } + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + s := IPv6SerializableHopByHopExtHdr(test.options) + length := s.length() + if length != len(test.expect) { + t.Fatalf("got s.length() = %d, want = %d", length, len(test.expect)) + } + b := make([]byte, length) + for i := range b { + // Fill the buffer with ones to ensure all padding is correctly set. + b[i] = 0xFF + } + if got := s.serializeInto(test.nextHeader, b); got != length { + t.Fatalf("got s.serializeInto(..) = %d, want = %d", got, length) + } + if diff := cmp.Diff(test.expect, b); diff != "" { + t.Fatalf("serialization mismatch (-want +got):\n%s", diff) + } + + // Deserialize the options and verify them. + optLen := (b[ipv6HopByHopExtHdrLengthOffset] + ipv6HopByHopExtHdrUnaccountedLenWords) * ipv6ExtHdrLenBytesPerUnit + iter := ipv6OptionsExtHdr(b[ipv6HopByHopExtHdrOptionsOffset:optLen]).Iter() + for _, testOpt := range test.options { + opt, done, err := iter.Next() + if err != nil { + t.Fatalf("iter.Next(): %s", err) + } + if done { + t.Fatalf("got iter.Next() = (%T, %t, _), want = (_, false, _)", opt, done) + } + test.validate(t, testOpt, opt) + } + opt, done, err := iter.Next() + if err != nil { + t.Fatalf("iter.Next(): %s", err) + } + if !done { + t.Fatalf("got iter.Next() = (%T, %t, _), want = (_, true, _)", opt, done) + } + }) + } +} + +var _ IPv6SerializableExtHdr = (*dummyIPv6ExtHdrSerializer)(nil) + +// dummyIPv6ExtHdrSerializer provides a generic implementation of +// IPv6SerializableExtHdr for use in tests. +// +// The dummy header always carries the nextHeader value in the first byte. +type dummyIPv6ExtHdrSerializer struct { + id IPv6ExtensionHeaderIdentifier + headerContents []byte +} + +// identifier implements IPv6SerializableExtHdr. +func (s *dummyIPv6ExtHdrSerializer) identifier() IPv6ExtensionHeaderIdentifier { + return s.id +} + +// length implements IPv6SerializableExtHdr. +func (s *dummyIPv6ExtHdrSerializer) length() int { + return len(s.headerContents) + 1 +} + +// serializeInto implements IPv6SerializableExtHdr. +func (s *dummyIPv6ExtHdrSerializer) serializeInto(nextHeader uint8, b []byte) int { + b[0] = nextHeader + return copy(b[1:], s.headerContents) + 1 +} + +func TestIPv6ExtHdrSerializer(t *testing.T) { + tests := []struct { + name string + headers []IPv6SerializableExtHdr + nextHeader tcpip.TransportProtocolNumber + expectSerialized []byte + expectNextHeader uint8 + }{ + { + name: "one header", + headers: []IPv6SerializableExtHdr{ + &dummyIPv6ExtHdrSerializer{ + id: 15, + headerContents: []byte{1, 2, 3, 4}, + }, + }, + nextHeader: TCPProtocolNumber, + expectSerialized: []byte{byte(TCPProtocolNumber), 1, 2, 3, 4}, + expectNextHeader: 15, + }, + { + name: "two headers", + headers: []IPv6SerializableExtHdr{ + &dummyIPv6ExtHdrSerializer{ + id: 22, + headerContents: []byte{1, 2, 3}, + }, + &dummyIPv6ExtHdrSerializer{ + id: 23, + headerContents: []byte{4, 5, 6}, + }, + }, + nextHeader: ICMPv6ProtocolNumber, + expectSerialized: []byte{ + 23, 1, 2, 3, + byte(ICMPv6ProtocolNumber), 4, 5, 6, + }, + expectNextHeader: 22, + }, + { + name: "no headers", + headers: []IPv6SerializableExtHdr{}, + nextHeader: UDPProtocolNumber, + expectSerialized: []byte{}, + expectNextHeader: byte(UDPProtocolNumber), + }, + } + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + s := IPv6ExtHdrSerializer(test.headers) + l := s.Length() + if got, want := l, len(test.expectSerialized); got != want { + t.Fatalf("got serialized length = %d, want = %d", got, want) + } + b := make([]byte, l) + for i := range b { + // Fill the buffer with garbage to make sure we're writing to all bytes. + b[i] = 0xFF + } + nextHeader, serializedLen := s.Serialize(test.nextHeader, b) + if serializedLen != len(test.expectSerialized) || nextHeader != test.expectNextHeader { + t.Errorf( + "got s.Serialize(..) = (%d, %d), want = (%d, %d)", + nextHeader, + serializedLen, + test.expectNextHeader, + len(test.expectSerialized), + ) + } + if diff := cmp.Diff(test.expectSerialized, b); diff != "" { + t.Errorf("serialization mismatch (-want +got):\n%s", diff) + } + }) + } +} diff --git a/pkg/tcpip/header/ipv6_fragment.go b/pkg/tcpip/header/ipv6_fragment.go index 018555a26..9d09f32eb 100644 --- a/pkg/tcpip/header/ipv6_fragment.go +++ b/pkg/tcpip/header/ipv6_fragment.go @@ -27,12 +27,11 @@ const ( idV6 = 4 ) -// IPv6FragmentFields contains the fields of an IPv6 fragment. It is used to describe the -// fields of a packet that needs to be encoded. -type IPv6FragmentFields struct { - // NextHeader is the "next header" field of an IPv6 fragment. - NextHeader uint8 +var _ IPv6SerializableExtHdr = (*IPv6SerializableFragmentExtHdr)(nil) +// IPv6SerializableFragmentExtHdr is used to serialize an IPv6 fragment +// extension header as defined in RFC 8200 section 4.5. +type IPv6SerializableFragmentExtHdr struct { // FragmentOffset is the "fragment offset" field of an IPv6 fragment. FragmentOffset uint16 @@ -43,6 +42,29 @@ type IPv6FragmentFields struct { Identification uint32 } +// identifier implements IPv6SerializableFragmentExtHdr. +func (h *IPv6SerializableFragmentExtHdr) identifier() IPv6ExtensionHeaderIdentifier { + return IPv6FragmentHeader +} + +// length implements IPv6SerializableFragmentExtHdr. +func (h *IPv6SerializableFragmentExtHdr) length() int { + return IPv6FragmentHeaderSize +} + +// serializeInto implements IPv6SerializableFragmentExtHdr. +func (h *IPv6SerializableFragmentExtHdr) serializeInto(nextHeader uint8, b []byte) int { + // Prevent too many bounds checks. + _ = b[IPv6FragmentHeaderSize:] + binary.BigEndian.PutUint32(b[idV6:], h.Identification) + binary.BigEndian.PutUint16(b[fragOff:], h.FragmentOffset<<ipv6FragmentExtHdrFragmentOffsetShift) + b[nextHdrFrag] = nextHeader + if h.M { + b[more] |= ipv6FragmentExtHdrMFlagMask + } + return IPv6FragmentHeaderSize +} + // IPv6Fragment represents an ipv6 fragment header stored in a byte array. // Most of the methods of IPv6Fragment access to the underlying slice without // checking the boundaries and could panic because of 'index out of range'. @@ -58,16 +80,6 @@ const ( IPv6FragmentHeaderSize = 8 ) -// Encode encodes all the fields of the ipv6 fragment. -func (b IPv6Fragment) Encode(i *IPv6FragmentFields) { - b[nextHdrFrag] = i.NextHeader - binary.BigEndian.PutUint16(b[fragOff:], i.FragmentOffset<<3) - if i.M { - b[more] |= 1 - } - binary.BigEndian.PutUint32(b[idV6:], i.Identification) -} - // IsValid performs basic validation on the fragment header. func (b IPv6Fragment) IsValid() bool { return len(b) >= IPv6FragmentHeaderSize diff --git a/pkg/tcpip/header/ipversion_test.go b/pkg/tcpip/header/ipversion_test.go index 17a49d4fa..b5540bf66 100644 --- a/pkg/tcpip/header/ipversion_test.go +++ b/pkg/tcpip/header/ipversion_test.go @@ -22,7 +22,7 @@ import ( func TestIPv4(t *testing.T) { b := header.IPv4(make([]byte, header.IPv4MinimumSize)) - b.Encode(&header.IPv4Fields{IHL: header.IPv4MinimumSize}) + b.Encode(&header.IPv4Fields{}) const want = header.IPv4Version if v := header.IPVersion(b); v != want { diff --git a/pkg/tcpip/header/mld.go b/pkg/tcpip/header/mld.go new file mode 100644 index 000000000..ffe03c76a --- /dev/null +++ b/pkg/tcpip/header/mld.go @@ -0,0 +1,103 @@ +// 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 header + +import ( + "encoding/binary" + "fmt" + "time" + + "gvisor.dev/gvisor/pkg/tcpip" +) + +const ( + // MLDMinimumSize is the minimum size for an MLD message. + MLDMinimumSize = 20 + + // MLDHopLimit is the Hop Limit for all IPv6 packets with an MLD message, as + // per RFC 2710 section 3. + MLDHopLimit = 1 + + // mldMaximumResponseDelayOffset is the offset to the Maximum Response Delay + // field within MLD. + mldMaximumResponseDelayOffset = 0 + + // mldMulticastAddressOffset is the offset to the Multicast Address field + // within MLD. + mldMulticastAddressOffset = 4 +) + +// MLD is a Multicast Listener Discovery message in an ICMPv6 packet. +// +// MLD will only contain the body of an ICMPv6 packet. +// +// As per RFC 2710 section 3, MLD messages have the following format (MLD only +// holds the bytes after the first four bytes in the diagram below): +// +// 0 1 2 3 +// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | Type | Code | Checksum | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | Maximum Response Delay | Reserved | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | | +// + + +// | | +// + Multicast Address + +// | | +// + + +// | | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +type MLD []byte + +// MaximumResponseDelay returns the Maximum Response Delay. +func (m MLD) MaximumResponseDelay() time.Duration { + // As per RFC 2710 section 3.4: + // + // The Maximum Response Delay field is meaningful only in Query + // messages, and specifies the maximum allowed delay before sending a + // responding Report, in units of milliseconds. In all other messages, + // it is set to zero by the sender and ignored by receivers. + return time.Duration(binary.BigEndian.Uint16(m[mldMaximumResponseDelayOffset:])) * time.Millisecond +} + +// SetMaximumResponseDelay sets the Maximum Response Delay field. +// +// maxRespDelayMS is the value in milliseconds. +func (m MLD) SetMaximumResponseDelay(maxRespDelayMS uint16) { + binary.BigEndian.PutUint16(m[mldMaximumResponseDelayOffset:], maxRespDelayMS) +} + +// MulticastAddress returns the Multicast Address. +func (m MLD) MulticastAddress() tcpip.Address { + // As per RFC 2710 section 3.5: + // + // In a Query message, the Multicast Address field is set to zero when + // sending a General Query, and set to a specific IPv6 multicast address + // when sending a Multicast-Address-Specific Query. + // + // In a Report or Done message, the Multicast Address field holds a + // specific IPv6 multicast address to which the message sender is + // listening or is ceasing to listen, respectively. + return tcpip.Address(m[mldMulticastAddressOffset:][:IPv6AddressSize]) +} + +// SetMulticastAddress sets the Multicast Address field. +func (m MLD) SetMulticastAddress(multicastAddress tcpip.Address) { + if n := copy(m[mldMulticastAddressOffset:], multicastAddress); n != IPv6AddressSize { + panic(fmt.Sprintf("copied %d bytes, expected to copy %d bytes", n, IPv6AddressSize)) + } +} diff --git a/pkg/tcpip/header/mld_test.go b/pkg/tcpip/header/mld_test.go new file mode 100644 index 000000000..0cecf10d4 --- /dev/null +++ b/pkg/tcpip/header/mld_test.go @@ -0,0 +1,61 @@ +// 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 header + +import ( + "encoding/binary" + "testing" + "time" + + "gvisor.dev/gvisor/pkg/tcpip" +) + +func TestMLD(t *testing.T) { + b := []byte{ + // Maximum Response Delay + 0, 0, + + // Reserved + 0, 0, + + // MulticastAddress + 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, + } + + const maxRespDelay = 513 + binary.BigEndian.PutUint16(b, maxRespDelay) + + mld := MLD(b) + + if got, want := mld.MaximumResponseDelay(), maxRespDelay*time.Millisecond; got != want { + t.Errorf("got mld.MaximumResponseDelay() = %s, want = %s", got, want) + } + + const newMaxRespDelay = 1234 + mld.SetMaximumResponseDelay(newMaxRespDelay) + if got, want := mld.MaximumResponseDelay(), newMaxRespDelay*time.Millisecond; got != want { + t.Errorf("got mld.MaximumResponseDelay() = %s, want = %s", got, want) + } + + if got, want := mld.MulticastAddress(), tcpip.Address([]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6}); got != want { + t.Errorf("got mld.MulticastAddress() = %s, want = %s", got, want) + } + + multicastAddress := tcpip.Address([]byte{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0}) + mld.SetMulticastAddress(multicastAddress) + if got := mld.MulticastAddress(); got != multicastAddress { + t.Errorf("got mld.MulticastAddress() = %s, want = %s", got, multicastAddress) + } +} 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/header/parse/parse.go b/pkg/tcpip/header/parse/parse.go index 5ca75c834..2042f214a 100644 --- a/pkg/tcpip/header/parse/parse.go +++ b/pkg/tcpip/header/parse/parse.go @@ -109,6 +109,9 @@ traverseExtensions: fragOffset = extHdr.FragmentOffset() fragMore = extHdr.More() } + rawPayload := it.AsRawHeader(true /* consume */) + extensionsSize = dataClone.Size() - rawPayload.Buf.Size() + break traverseExtensions case header.IPv6RawPayloadHeader: // We've found the payload after any extensions. diff --git a/pkg/tcpip/header/udp.go b/pkg/tcpip/header/udp.go index 98bdd29db..a6d4fcd59 100644 --- a/pkg/tcpip/header/udp.go +++ b/pkg/tcpip/header/udp.go @@ -36,10 +36,10 @@ const ( // UDPFields contains the fields of a UDP packet. It is used to describe the // fields of a packet that needs to be encoded. type UDPFields struct { - // SrcPort is the "source port" field of a UDP packet. + // SrcPort is the "Source Port" field of a UDP packet. SrcPort uint16 - // DstPort is the "destination port" field of a UDP packet. + // DstPort is the "Destination Port" field of a UDP packet. DstPort uint16 // Length is the "length" field of a UDP packet. @@ -64,52 +64,57 @@ const ( UDPProtocolNumber tcpip.TransportProtocolNumber = 17 ) -// SourcePort returns the "source port" field of the udp header. +// SourcePort returns the "Source Port" field of the UDP header. func (b UDP) SourcePort() uint16 { return binary.BigEndian.Uint16(b[udpSrcPort:]) } -// DestinationPort returns the "destination port" field of the udp header. +// DestinationPort returns the "Destination Port" field of the UDP header. func (b UDP) DestinationPort() uint16 { return binary.BigEndian.Uint16(b[udpDstPort:]) } -// Length returns the "length" field of the udp header. +// Length returns the "Length" field of the UDP header. func (b UDP) Length() uint16 { return binary.BigEndian.Uint16(b[udpLength:]) } // Payload returns the data contained in the UDP datagram. func (b UDP) Payload() []byte { - return b[UDPMinimumSize:] + return b[:b.Length()][UDPMinimumSize:] } -// Checksum returns the "checksum" field of the udp header. +// Checksum returns the "checksum" field of the UDP header. func (b UDP) Checksum() uint16 { return binary.BigEndian.Uint16(b[udpChecksum:]) } -// SetSourcePort sets the "source port" field of the udp header. +// SetSourcePort sets the "source port" field of the UDP header. func (b UDP) SetSourcePort(port uint16) { binary.BigEndian.PutUint16(b[udpSrcPort:], port) } -// SetDestinationPort sets the "destination port" field of the udp header. +// SetDestinationPort sets the "destination port" field of the UDP header. func (b UDP) SetDestinationPort(port uint16) { binary.BigEndian.PutUint16(b[udpDstPort:], port) } -// SetChecksum sets the "checksum" field of the udp header. +// SetChecksum sets the "checksum" field of the UDP header. func (b UDP) SetChecksum(checksum uint16) { binary.BigEndian.PutUint16(b[udpChecksum:], checksum) } -// SetLength sets the "length" field of the udp header. +// SetLength sets the "length" field of the UDP header. func (b UDP) SetLength(length uint16) { binary.BigEndian.PutUint16(b[udpLength:], length) } -// CalculateChecksum calculates the checksum of the udp packet, given the +// PayloadLength returns the length of the payload following the UDP header. +func (b UDP) PayloadLength() uint16 { + return b.Length() - UDPMinimumSize +} + +// CalculateChecksum calculates the checksum of the UDP packet, given the // checksum of the network-layer pseudo-header and the checksum of the payload. func (b UDP) CalculateChecksum(partialChecksum uint16) uint16 { // Calculate the rest of the checksum. |