diff options
Diffstat (limited to 'pkg/tcpip/header')
| -rw-r--r-- | pkg/tcpip/header/igmp.go | 166 | ||||
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 3 |
2 files changed, 169 insertions, 0 deletions
diff --git a/pkg/tcpip/header/igmp.go b/pkg/tcpip/header/igmp.go new file mode 100644 index 000000000..e0f5d46f4 --- /dev/null +++ b/pkg/tcpip/header/igmp.go @@ -0,0 +1,166 @@ +// 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" + + "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() byte { return 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 +} diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go index 91fe7b6a5..5fddd2af6 100644 --- a/pkg/tcpip/header/ipv4.go +++ b/pkg/tcpip/header/ipv4.go @@ -157,6 +157,9 @@ 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. |