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// 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 ipv6
import (
"fmt"
"time"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/network/ip"
"gvisor.dev/gvisor/pkg/tcpip/stack"
)
const (
// UnsolicitedReportIntervalMax is the maximum delay between sending
// unsolicited MLD reports.
//
// Obtained from RFC 2710 Section 7.10.
UnsolicitedReportIntervalMax = 10 * time.Second
)
// MLDOptions holds options for MLD.
type MLDOptions struct {
// Enabled indicates whether MLD will be performed.
//
// When enabled, MLD may transmit MLD report and done messages when
// joining and leaving multicast groups respectively, and handle incoming
// MLD packets.
Enabled bool
}
var _ ip.MulticastGroupProtocol = (*mldState)(nil)
// mldState is the per-interface MLD state.
//
// mldState.init MUST be called to initialize the MLD state.
type mldState struct {
// The IPv6 endpoint this mldState is for.
ep *endpoint
genericMulticastProtocol ip.GenericMulticastProtocolState
}
// SendReport implements ip.MulticastGroupProtocol.
func (mld *mldState) SendReport(groupAddress tcpip.Address) *tcpip.Error {
return mld.writePacket(groupAddress, groupAddress, header.ICMPv6MulticastListenerReport)
}
// SendLeave implements ip.MulticastGroupProtocol.
func (mld *mldState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
return mld.writePacket(header.IPv6AllRoutersMulticastAddress, groupAddress, header.ICMPv6MulticastListenerDone)
}
// init sets up an mldState struct, and is required to be called before using
// a new mldState.
func (mld *mldState) init(ep *endpoint, opts MLDOptions) {
mld.ep = ep
mld.genericMulticastProtocol.Init(ip.GenericMulticastProtocolOptions{
Enabled: opts.Enabled,
Rand: ep.protocol.stack.Rand(),
Clock: ep.protocol.stack.Clock(),
Protocol: mld,
MaxUnsolicitedReportDelay: UnsolicitedReportIntervalMax,
AllNodesAddress: header.IPv6AllNodesMulticastAddress,
})
}
func (mld *mldState) handleMulticastListenerQuery(mldHdr header.MLD) {
mld.genericMulticastProtocol.HandleQuery(mldHdr.MulticastAddress(), mldHdr.MaximumResponseDelay())
}
func (mld *mldState) handleMulticastListenerReport(mldHdr header.MLD) {
mld.genericMulticastProtocol.HandleReport(mldHdr.MulticastAddress())
}
// joinGroup handles joining a new group and sending and scheduling the required
// messages.
//
// If the group is already joined, returns tcpip.ErrDuplicateAddress.
func (mld *mldState) joinGroup(groupAddress tcpip.Address) {
mld.genericMulticastProtocol.JoinGroup(groupAddress, !mld.ep.Enabled() /* dontInitialize */)
}
// isInGroup returns true if the specified group has been joined locally.
func (mld *mldState) isInGroup(groupAddress tcpip.Address) bool {
return mld.genericMulticastProtocol.IsLocallyJoined(groupAddress)
}
// leaveGroup handles removing the group from the membership map, cancels any
// delay timers associated with that group, and sends the Done message, if
// required.
func (mld *mldState) leaveGroup(groupAddress tcpip.Address) *tcpip.Error {
// LeaveGroup returns false only if the group was not joined.
if mld.genericMulticastProtocol.LeaveGroup(groupAddress) {
return nil
}
return tcpip.ErrBadLocalAddress
}
// softLeaveAll leaves all groups from the perspective of MLD, but remains
// joined locally.
func (mld *mldState) softLeaveAll() {
mld.genericMulticastProtocol.MakeAllNonMember()
}
// initializeAll attemps to initialize the MLD state for each group that has
// been joined locally.
func (mld *mldState) initializeAll() {
mld.genericMulticastProtocol.InitializeGroups()
}
func (mld *mldState) writePacket(destAddress, groupAddress tcpip.Address, mldType header.ICMPv6Type) *tcpip.Error {
sentStats := mld.ep.protocol.stack.Stats().ICMP.V6PacketsSent
var mldStat *tcpip.StatCounter
switch mldType {
case header.ICMPv6MulticastListenerReport:
mldStat = sentStats.MulticastListenerReport
case header.ICMPv6MulticastListenerDone:
mldStat = sentStats.MulticastListenerDone
default:
panic(fmt.Sprintf("unrecognized mld type = %d", mldType))
}
icmp := header.ICMPv6(buffer.NewView(header.ICMPv6HeaderSize + header.MLDMinimumSize))
icmp.SetType(mldType)
header.MLD(icmp.MessageBody()).SetMulticastAddress(groupAddress)
// TODO(gvisor.dev/issue/4888): We should not use the unspecified address,
// rather we should select an appropriate local address.
localAddress := header.IPv6Any
icmp.SetChecksum(header.ICMPv6Checksum(icmp, localAddress, destAddress, buffer.VectorisedView{}))
pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
ReserveHeaderBytes: int(mld.ep.MaxHeaderLength()),
Data: buffer.View(icmp).ToVectorisedView(),
})
mld.ep.addIPHeader(localAddress, destAddress, pkt, stack.NetworkHeaderParams{
Protocol: header.ICMPv6ProtocolNumber,
TTL: header.MLDHopLimit,
})
// TODO(b/162198658): set the ROUTER_ALERT option when sending Host
// Membership Reports.
if err := mld.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv6Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
sentStats.Dropped.Increment()
return err
}
mldStat.Increment()
return nil
}
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