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356 lines
12 KiB
356 lines
12 KiB
// Copyright 2012 Google, Inc. All rights reserved.
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// Copyright 2009-2011 Andreas Krennmair. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file in the root of the source
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// tree.
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package layers
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import (
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"encoding/binary"
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"errors"
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"net"
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"time"
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"github.com/google/gopacket"
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)
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type IGMPType uint8
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const (
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IGMPMembershipQuery IGMPType = 0x11 // General or group specific query
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IGMPMembershipReportV1 IGMPType = 0x12 // Version 1 Membership Report
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IGMPMembershipReportV2 IGMPType = 0x16 // Version 2 Membership Report
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IGMPLeaveGroup IGMPType = 0x17 // Leave Group
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IGMPMembershipReportV3 IGMPType = 0x22 // Version 3 Membership Report
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)
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// String conversions for IGMP message types
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func (i IGMPType) String() string {
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switch i {
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case IGMPMembershipQuery:
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return "IGMP Membership Query"
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case IGMPMembershipReportV1:
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return "IGMPv1 Membership Report"
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case IGMPMembershipReportV2:
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return "IGMPv2 Membership Report"
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case IGMPMembershipReportV3:
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return "IGMPv3 Membership Report"
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case IGMPLeaveGroup:
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return "Leave Group"
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default:
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return ""
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}
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}
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type IGMPv3GroupRecordType uint8
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const (
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IGMPIsIn IGMPv3GroupRecordType = 0x01 // Type MODE_IS_INCLUDE, source addresses x
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IGMPIsEx IGMPv3GroupRecordType = 0x02 // Type MODE_IS_EXCLUDE, source addresses x
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IGMPToIn IGMPv3GroupRecordType = 0x03 // Type CHANGE_TO_INCLUDE_MODE, source addresses x
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IGMPToEx IGMPv3GroupRecordType = 0x04 // Type CHANGE_TO_EXCLUDE_MODE, source addresses x
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IGMPAllow IGMPv3GroupRecordType = 0x05 // Type ALLOW_NEW_SOURCES, source addresses x
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IGMPBlock IGMPv3GroupRecordType = 0x06 // Type BLOCK_OLD_SOURCES, source addresses x
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)
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func (i IGMPv3GroupRecordType) String() string {
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switch i {
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case IGMPIsIn:
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return "MODE_IS_INCLUDE"
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case IGMPIsEx:
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return "MODE_IS_EXCLUDE"
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case IGMPToIn:
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return "CHANGE_TO_INCLUDE_MODE"
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case IGMPToEx:
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return "CHANGE_TO_EXCLUDE_MODE"
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case IGMPAllow:
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return "ALLOW_NEW_SOURCES"
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case IGMPBlock:
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return "BLOCK_OLD_SOURCES"
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default:
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return ""
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}
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}
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// IGMP represents an IGMPv3 message.
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type IGMP struct {
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BaseLayer
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Type IGMPType
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MaxResponseTime time.Duration
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Checksum uint16
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GroupAddress net.IP
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SupressRouterProcessing bool
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RobustnessValue uint8
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IntervalTime time.Duration
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SourceAddresses []net.IP
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NumberOfGroupRecords uint16
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NumberOfSources uint16
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GroupRecords []IGMPv3GroupRecord
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Version uint8 // IGMP protocol version
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}
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// IGMPv1or2 stores header details for an IGMPv1 or IGMPv2 packet.
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//
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// 0 1 2 3
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// 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
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Type | Max Resp Time | Checksum |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Group Address |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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type IGMPv1or2 struct {
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BaseLayer
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Type IGMPType // IGMP message type
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MaxResponseTime time.Duration // meaningful only in Membership Query messages
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Checksum uint16 // 16-bit checksum of entire ip payload
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GroupAddress net.IP // either 0 or an IP multicast address
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Version uint8
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}
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// decodeResponse dissects IGMPv1 or IGMPv2 packet.
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func (i *IGMPv1or2) decodeResponse(data []byte) error {
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if len(data) < 8 {
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return errors.New("IGMP packet too small")
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}
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i.MaxResponseTime = igmpTimeDecode(data[1])
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i.Checksum = binary.BigEndian.Uint16(data[2:4])
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i.GroupAddress = net.IP(data[4:8])
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return nil
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}
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// 0 1 2 3
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// 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
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Type = 0x22 | Reserved | Checksum |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Reserved | Number of Group Records (M) |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | |
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// . Group Record [1] .
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// | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | |
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// . Group Record [2] .
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// | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | |
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// . Group Record [M] .
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// | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Record Type | Aux Data Len | Number of Sources (N) |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Multicast Address |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Source Address [1] |
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// +- -+
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// | Source Address [2] |
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// +- -+
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// | Source Address [N] |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | |
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// . Auxiliary Data .
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// | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// IGMPv3GroupRecord stores individual group records for a V3 Membership Report message.
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type IGMPv3GroupRecord struct {
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Type IGMPv3GroupRecordType
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AuxDataLen uint8 // this should always be 0 as per IGMPv3 spec.
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NumberOfSources uint16
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MulticastAddress net.IP
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SourceAddresses []net.IP
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AuxData uint32 // NOT USED
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}
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func (i *IGMP) decodeIGMPv3MembershipReport(data []byte) error {
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if len(data) < 8 {
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return errors.New("IGMPv3 Membership Report too small #1")
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}
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i.Checksum = binary.BigEndian.Uint16(data[2:4])
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i.NumberOfGroupRecords = binary.BigEndian.Uint16(data[6:8])
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recordOffset := 8
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for j := 0; j < int(i.NumberOfGroupRecords); j++ {
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if len(data) < recordOffset+8 {
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return errors.New("IGMPv3 Membership Report too small #2")
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}
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var gr IGMPv3GroupRecord
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gr.Type = IGMPv3GroupRecordType(data[recordOffset])
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gr.AuxDataLen = data[recordOffset+1]
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gr.NumberOfSources = binary.BigEndian.Uint16(data[recordOffset+2 : recordOffset+4])
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gr.MulticastAddress = net.IP(data[recordOffset+4 : recordOffset+8])
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if len(data) < recordOffset+8+int(gr.NumberOfSources)*4 {
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return errors.New("IGMPv3 Membership Report too small #3")
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}
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// append source address records.
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for i := 0; i < int(gr.NumberOfSources); i++ {
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sourceAddr := net.IP(data[recordOffset+8+i*4 : recordOffset+12+i*4])
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gr.SourceAddresses = append(gr.SourceAddresses, sourceAddr)
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}
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i.GroupRecords = append(i.GroupRecords, gr)
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recordOffset += 8 + 4*int(gr.NumberOfSources)
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}
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return nil
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}
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// 0 1 2 3
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// 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
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Type = 0x11 | Max Resp Code | Checksum |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Group Address |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Resv |S| QRV | QQIC | Number of Sources (N) |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Source Address [1] |
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// +- -+
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// | Source Address [2] |
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// +- . -+
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// | Source Address [N] |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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//
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// decodeIGMPv3MembershipQuery parses the IGMPv3 message of type 0x11
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func (i *IGMP) decodeIGMPv3MembershipQuery(data []byte) error {
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if len(data) < 12 {
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return errors.New("IGMPv3 Membership Query too small #1")
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}
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i.MaxResponseTime = igmpTimeDecode(data[1])
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i.Checksum = binary.BigEndian.Uint16(data[2:4])
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i.SupressRouterProcessing = data[8]&0x8 != 0
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i.GroupAddress = net.IP(data[4:8])
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i.RobustnessValue = data[8] & 0x7
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i.IntervalTime = igmpTimeDecode(data[9])
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i.NumberOfSources = binary.BigEndian.Uint16(data[10:12])
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if len(data) < 12+int(i.NumberOfSources)*4 {
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return errors.New("IGMPv3 Membership Query too small #2")
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}
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for j := 0; j < int(i.NumberOfSources); j++ {
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i.SourceAddresses = append(i.SourceAddresses, net.IP(data[12+j*4:16+j*4]))
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}
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return nil
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}
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// igmpTimeDecode decodes the duration created by the given byte, using the
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// algorithm in http://www.rfc-base.org/txt/rfc-3376.txt section 4.1.1.
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func igmpTimeDecode(t uint8) time.Duration {
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if t&0x80 == 0 {
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return time.Millisecond * 100 * time.Duration(t)
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}
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mant := (t & 0x70) >> 4
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exp := t & 0x0F
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return time.Millisecond * 100 * time.Duration((mant|0x10)<<(exp+3))
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}
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// LayerType returns LayerTypeIGMP for the V1,2,3 message protocol formats.
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func (i *IGMP) LayerType() gopacket.LayerType { return LayerTypeIGMP }
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func (i *IGMPv1or2) LayerType() gopacket.LayerType { return LayerTypeIGMP }
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func (i *IGMPv1or2) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
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if len(data) < 8 {
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return errors.New("IGMP Packet too small")
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}
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i.Type = IGMPType(data[0])
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i.MaxResponseTime = igmpTimeDecode(data[1])
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i.Checksum = binary.BigEndian.Uint16(data[2:4])
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i.GroupAddress = net.IP(data[4:8])
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return nil
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}
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func (i *IGMPv1or2) NextLayerType() gopacket.LayerType {
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return gopacket.LayerTypeZero
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}
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func (i *IGMPv1or2) CanDecode() gopacket.LayerClass {
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return LayerTypeIGMP
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}
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// DecodeFromBytes decodes the given bytes into this layer.
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func (i *IGMP) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
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if len(data) < 1 {
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return errors.New("IGMP packet is too small")
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}
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// common IGMP header values between versions 1..3 of IGMP specification..
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i.Type = IGMPType(data[0])
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switch i.Type {
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case IGMPMembershipQuery:
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i.decodeIGMPv3MembershipQuery(data)
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case IGMPMembershipReportV3:
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i.decodeIGMPv3MembershipReport(data)
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default:
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return errors.New("unsupported IGMP type")
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}
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return nil
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}
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// CanDecode returns the set of layer types that this DecodingLayer can decode.
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func (i *IGMP) CanDecode() gopacket.LayerClass {
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return LayerTypeIGMP
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}
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// NextLayerType returns the layer type contained by this DecodingLayer.
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func (i *IGMP) NextLayerType() gopacket.LayerType {
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return gopacket.LayerTypeZero
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}
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// decodeIGMP will parse IGMP v1,2 or 3 protocols. Checks against the
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// IGMP type are performed against byte[0], logic then iniitalizes and
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// passes the appropriate struct (IGMP or IGMPv1or2) to
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// decodingLayerDecoder.
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func decodeIGMP(data []byte, p gopacket.PacketBuilder) error {
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if len(data) < 1 {
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return errors.New("IGMP packet is too small")
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}
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// byte 0 contains IGMP message type.
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switch IGMPType(data[0]) {
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case IGMPMembershipQuery:
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// IGMPv3 Membership Query payload is >= 12
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if len(data) >= 12 {
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i := &IGMP{Version: 3}
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return decodingLayerDecoder(i, data, p)
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} else if len(data) == 8 {
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i := &IGMPv1or2{}
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if data[1] == 0x00 {
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i.Version = 1 // IGMPv1 has a query length of 8 and MaxResp = 0
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} else {
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i.Version = 2 // IGMPv2 has a query length of 8 and MaxResp != 0
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}
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return decodingLayerDecoder(i, data, p)
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}
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case IGMPMembershipReportV3:
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i := &IGMP{Version: 3}
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return decodingLayerDecoder(i, data, p)
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case IGMPMembershipReportV1:
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i := &IGMPv1or2{Version: 1}
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return decodingLayerDecoder(i, data, p)
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case IGMPLeaveGroup, IGMPMembershipReportV2:
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// leave group and Query Report v2 used in IGMPv2 only.
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i := &IGMPv1or2{Version: 2}
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return decodingLayerDecoder(i, data, p)
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default:
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}
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return errors.New("Unable to determine IGMP type.")
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}
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