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Merge pull request #700 from Arceliar/multicast

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Multicast
This commit is contained in:
Neil Alexander 2020-05-25 22:17:50 +01:00 committed by GitHub
commit 895bd681a1
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2 changed files with 168 additions and 143 deletions
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306
src/multicast/multicast.go
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@ -15,57 +15,45 @@ import (
"golang.org/x/net/ipv6"
)
const (
// GroupAddr contains the multicast group and port used for multicast packets.
GroupAddr = "[ff02::114]:9001"
)
// Multicast represents the multicast advertisement and discovery mechanism used
// by Yggdrasil to find peers on the same subnet. When a beacon is received on a
// configured multicast interface, Yggdrasil will attempt to peer with that node
// automatically.
type Multicast struct {
phony.Inbox
core *yggdrasil.Core
config *config.NodeState
log *log.Logger
sock *ipv6.PacketConn
groupAddr *net.UDPAddr
listeners map[string]*multicastInterface
listenPort uint16
isOpen bool
monitor *time.Timer
platformhandler *time.Timer
_interfaces map[string]net.Interface
_interfaceAddrs map[string]addrInfo
core *yggdrasil.Core
config *config.NodeState
log *log.Logger
sock *ipv6.PacketConn
groupAddr string
listeners map[string]*listenerInfo
listenPort uint16
isOpen bool
_interfaces map[string]interfaceInfo
}
type addrInfo struct {
type interfaceInfo struct {
iface net.Interface
addrs []net.Addr
time time.Time
}
type multicastInterface struct {
phony.Inbox
sock *ipv6.PacketConn
destAddr net.UDPAddr
type listenerInfo struct {
listener *yggdrasil.TcpListener
zone string
timer *time.Timer
time time.Time
interval time.Duration
stop chan interface{}
}
// Init prepares the multicast interface for use.
func (m *Multicast) Init(core *yggdrasil.Core, state *config.NodeState, log *log.Logger, options interface{}) (err error) {
func (m *Multicast) Init(core *yggdrasil.Core, state *config.NodeState, log *log.Logger, options interface{}) error {
m.core = core
m.config = state
m.log = log
m.listeners = make(map[string]*multicastInterface)
m.listeners = make(map[string]*listenerInfo)
m._interfaces = make(map[string]interfaceInfo)
current := m.config.GetCurrent()
m.listenPort = current.LinkLocalTCPPort
m.groupAddr, err = net.ResolveUDPAddr("udp6", GroupAddr)
return
m.groupAddr = "[ff02::114]:9001"
return nil
}
// Start starts the multicast interface. This launches goroutines which will
@ -88,7 +76,7 @@ func (m *Multicast) _start() error {
return nil
}
m.log.Infoln("Starting multicast module")
addr, err := net.ResolveUDPAddr("udp", GroupAddr)
addr, err := net.ResolveUDPAddr("udp", m.groupAddr)
if err != nil {
return err
}
@ -108,7 +96,7 @@ func (m *Multicast) _start() error {
m.isOpen = true
go m.listen()
m.Act(nil, m._multicastStarted)
m.Act(nil, m._monitorInterfaceChanges)
m.Act(nil, m._announce)
return nil
}
@ -135,13 +123,6 @@ func (m *Multicast) Stop() error {
func (m *Multicast) _stop() error {
m.log.Infoln("Stopping multicast module")
m.isOpen = false
for name := range m.listeners {
close(m.listeners[name].stop)
delete(m.listeners, name)
}
if m.platformhandler != nil {
m.platformhandler.Stop()
}
if m.sock != nil {
m.sock.Close()
}
@ -174,92 +155,35 @@ func (m *Multicast) _updateConfig(config *config.NodeConfig) {
m.log.Debugln("Reloaded multicast configuration successfully")
}
func (m *Multicast) _monitorInterfaceChanges() {
m._updateInterfaces() // update interfaces and interfaceAddrs
// Look for interfaces we don't know about yet.
for name, intf := range m._interfaces {
if _, ok := m.listeners[name]; !ok {
// Look up interface addresses.
addrs := m._interfaceAddrs[intf.Name].addrs
// Find the first link-local address.
for _, addr := range addrs {
addrIP, _, _ := net.ParseCIDR(addr.String())
// Join the multicast group.
m.sock.JoinGroup(&intf, m.groupAddr)
// Construct a listener on this address.
listenaddr := fmt.Sprintf("[%s%%%s]:%d", addrIP, intf.Name, m.listenPort)
listener, err := m.core.ListenTCP(listenaddr)
if err != nil {
m.log.Warnln("Not multicasting on", name, "due to error:", err)
continue
}
// This is a new interface. Start an announcer for it.
multicastInterface := &multicastInterface{
sock: m.sock,
destAddr: *m.groupAddr,
listener: listener,
stop: make(chan interface{}),
zone: name,
}
multicastInterface.Act(m, multicastInterface._announce)
m.listeners[name] = multicastInterface
m.log.Debugln("Started multicasting on", name)
break
}
func (m *Multicast) _updateInterfaces() {
interfaces := make(map[string]interfaceInfo)
intfs := m.getAllowedInterfaces()
for _, intf := range intfs {
addrs, err := intf.Addrs()
if err != nil {
m.log.Warnf("Failed up get addresses for interface %s: %s", intf.Name, err)
continue
}
interfaces[intf.Name] = interfaceInfo{
iface: intf,
addrs: addrs,
}
}
// Look for interfaces we knew about but are no longer there.
for name, intf := range m.listeners {
if _, ok := m._interfaces[name]; !ok {
// This is a disappeared interface. Stop the announcer.
close(intf.stop)
delete(m.listeners, name)
m.log.Debugln("Stopped multicasting on", name)
}
}
// Queue the next check.
m.monitor = time.AfterFunc(time.Second, func() {
m.Act(nil, m._monitorInterfaceChanges)
})
m._interfaces = interfaces
}
func (m *multicastInterface) _announce() {
// Check if the multicast interface has been stopped. This will happen
// if it disappears from the system or goes down.
select {
case <-m.stop:
return
default:
}
// Send the beacon.
lladdr := m.listener.Listener.Addr().String()
if a, err := net.ResolveTCPAddr("tcp6", lladdr); err == nil {
a.Zone = ""
msg := []byte(a.String())
m.sock.WriteTo(msg, nil, &m.destAddr)
}
// Queue the next beacon.
if m.interval.Seconds() < 15 {
m.interval += time.Second
}
m.timer = time.AfterFunc(m.interval, func() {
m.Act(nil, m._announce)
})
}
// GetInterfaces returns the currently known/enabled multicast interfaces. It is
// expected that UpdateInterfaces has been called at least once before calling
// this method.
func (m *Multicast) Interfaces() map[string]net.Interface {
var interfaces map[string]net.Interface
interfaces := make(map[string]net.Interface)
phony.Block(m, func() {
interfaces = m._interfaces
for _, info := range m._interfaces {
interfaces[info.iface.Name] = info.iface
}
})
return interfaces
}
func (m *Multicast) _updateInterfaces() {
// getAllowedInterfaces returns the currently known/enabled multicast interfaces.
func (m *Multicast) getAllowedInterfaces() map[string]net.Interface {
interfaces := make(map[string]net.Interface)
// Get interface expressions from config
current := m.config.GetCurrent()
@ -270,7 +194,6 @@ func (m *Multicast) _updateInterfaces() {
panic(err)
}
// Work out which interfaces to announce on
interfaceAddrs := make(map[string]addrInfo)
for _, iface := range allifaces {
if iface.Flags&net.FlagUp == 0 {
// Ignore interfaces that are down
@ -284,26 +207,6 @@ func (m *Multicast) _updateInterfaces() {
// Ignore point-to-point interfaces
continue
}
var aInfo addrInfo
var isIn bool
if aInfo, isIn = m._interfaceAddrs[iface.Name]; isIn && time.Since(aInfo.time) < time.Minute {
// don't call iface.Addrs, it's unlikely things have changed
} else {
aInfo.addrs, _ = iface.Addrs()
aInfo.time = time.Now()
}
lladdrs := aInfo.addrs[:0]
for _, addr := range aInfo.addrs {
addrIP, _, _ := net.ParseCIDR(addr.String())
if addrIP.To4() == nil && addrIP.IsLinkLocalUnicast() {
lladdrs = append(lladdrs, addr)
}
}
aInfo.addrs = lladdrs
if len(lladdrs) == 0 {
// Ignore interfaces without link-local addresses
continue
}
for _, expr := range exprs {
// Compile each regular expression
e, err := regexp.Compile(expr)
@ -313,16 +216,132 @@ func (m *Multicast) _updateInterfaces() {
// Does the interface match the regular expression? Store it if so
if e.MatchString(iface.Name) {
interfaces[iface.Name] = iface
interfaceAddrs[iface.Name] = aInfo
}
}
}
m._interfaces = interfaces
m._interfaceAddrs = interfaceAddrs
return interfaces
}
func (m *Multicast) _announce() {
if !m.isOpen {
return
}
m._updateInterfaces()
groupAddr, err := net.ResolveUDPAddr("udp6", m.groupAddr)
if err != nil {
panic(err)
}
destAddr, err := net.ResolveUDPAddr("udp6", m.groupAddr)
if err != nil {
panic(err)
}
// There might be interfaces that we configured listeners for but are no
// longer up - if that's the case then we should stop the listeners
for name, info := range m.listeners {
// Prepare our stop function!
stop := func() {
info.listener.Stop()
delete(m.listeners, name)
m.log.Debugln("No longer multicasting on", name)
}
// If the interface is no longer visible on the system then stop the
// listener, as another one will be started further down
if _, ok := m._interfaces[name]; !ok {
stop()
continue
}
// It's possible that the link-local listener address has changed so if
// that is the case then we should clean up the interface listener
found := false
listenaddr, err := net.ResolveTCPAddr("tcp6", info.listener.Listener.Addr().String())
if err != nil {
stop()
continue
}
// Find the interface that matches the listener
if intf, err := net.InterfaceByName(name); err == nil {
if addrs, err := intf.Addrs(); err == nil {
// Loop through the addresses attached to that listener and see if any
// of them match the current address of the listener
for _, addr := range addrs {
if ip, _, err := net.ParseCIDR(addr.String()); err == nil {
// Does the interface address match our listener address?
if ip.Equal(listenaddr.IP) {
found = true
break
}
}
}
}
}
// If the address has not been found on the adapter then we should stop
// and clean up the TCP listener. A new one will be created below if a
// suitable link-local address is found
if !found {
stop()
}
}
// Now that we have a list of valid interfaces from the operating system,
// we can start checking if we can send multicasts on them
for _, info := range m._interfaces {
iface := info.iface
for _, addr := range info.addrs {
addrIP, _, _ := net.ParseCIDR(addr.String())
// Ignore IPv4 addresses
if addrIP.To4() != nil {
continue
}
// Ignore non-link-local addresses
if !addrIP.IsLinkLocalUnicast() {
continue
}
// Join the multicast group
m.sock.JoinGroup(&iface, groupAddr)
// Try and see if we already have a TCP listener for this interface
var info *listenerInfo
if nfo, ok := m.listeners[iface.Name]; !ok || nfo.listener.Listener == nil {
// No listener was found - let's create one
listenaddr := fmt.Sprintf("[%s%%%s]:%d", addrIP, iface.Name, m.listenPort)
if li, err := m.core.ListenTCP(listenaddr); err == nil {
m.log.Debugln("Started multicasting on", iface.Name)
// Store the listener so that we can stop it later if needed
info = &listenerInfo{listener: li, time: time.Now()}
m.listeners[iface.Name] = info
} else {
m.log.Warnln("Not multicasting on", iface.Name, "due to error:", err)
}
} else {
// An existing listener was found
info = m.listeners[iface.Name]
}
// Make sure nothing above failed for some reason
if info == nil {
continue
}
if time.Since(info.time) < info.interval {
continue
}
// Get the listener details and construct the multicast beacon
lladdr := info.listener.Listener.Addr().String()
if a, err := net.ResolveTCPAddr("tcp6", lladdr); err == nil {
a.Zone = ""
destAddr.Zone = iface.Name
msg := []byte(a.String())
m.sock.WriteTo(msg, nil, destAddr)
}
if info.interval.Seconds() < 15 {
info.interval += time.Second
}
break
}
}
time.AfterFunc(time.Second, func() {
m.Act(nil, m._announce)
})
}
func (m *Multicast) listen() {
groupAddr, err := net.ResolveUDPAddr("udp6", GroupAddr)
groupAddr, err := net.ResolveUDPAddr("udp6", m.groupAddr)
if err != nil {
panic(err)
}
@ -355,8 +374,11 @@ func (m *Multicast) listen() {
if addr.IP.String() != from.IP.String() {
continue
}
// Note that m.Interfaces would block if it was being run by the actor itself
if _, ok := m.Interfaces()[from.Zone]; ok {
var interfaces map[string]interfaceInfo
phony.Block(m, func() {
interfaces = m._interfaces
})
if _, ok := interfaces[from.Zone]; ok {
addr.Zone = ""
if err := m.core.CallPeer("tcp://"+addr.String(), from.Zone); err != nil {
m.log.Debugln("Call from multicast failed:", err)

5
src/multicast/multicast_darwin.go
View File

@ -32,6 +32,9 @@ import (
var awdlGoroutineStarted bool
func (m *Multicast) _multicastStarted() {
if !m.isOpen {
return
}
C.StopAWDLBrowsing()
for intf := range m._interfaces {
if intf == "awdl0" {
@ -39,7 +42,7 @@ func (m *Multicast) _multicastStarted() {
break
}
}
m.platformhandler = time.AfterFunc(time.Minute, func() {
time.AfterFunc(time.Minute, func() {
m.Act(nil, m._multicastStarted)
})
}