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mirror of https://github.com/cwinfo/yggdrasil-go.git synced 2024-12-23 04:05:39 +00:00

Refactor the multicast code a bit

This commit is contained in:
Neil Alexander 2020-05-02 22:26:41 +01:00
parent 78b5f88e4b
commit a115d18595
No known key found for this signature in database
GPG Key ID: A02A2019A2BB0944

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@ -15,40 +15,57 @@ 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 string
listeners map[string]*listenerInfo
listenPort uint16
isOpen bool
announcer *time.Timer
platformhandler *time.Timer
core *yggdrasil.Core
config *config.NodeState
log *log.Logger
sock *ipv6.PacketConn
groupAddr *net.UDPAddr
listeners map[string]*multicastInterface
listenPort uint16
isOpen bool
interfaceMonitor *time.Timer
announcer *time.Timer
platformhandler *time.Timer
}
type listenerInfo struct {
type multicastInterface struct {
phony.Inbox
sock *ipv6.PacketConn
destAddr net.UDPAddr
listener *yggdrasil.TcpListener
time time.Time
zone string
timer *time.Timer
interval time.Duration
send chan<- beacon
stop chan interface{}
}
type beacon struct {
llAddr string
zone string
}
// Init prepares the multicast interface for use.
func (m *Multicast) Init(core *yggdrasil.Core, state *config.NodeState, log *log.Logger, options interface{}) error {
func (m *Multicast) Init(core *yggdrasil.Core, state *config.NodeState, log *log.Logger, options interface{}) (err error) {
m.core = core
m.config = state
m.log = log
m.listeners = make(map[string]*listenerInfo)
m.listeners = make(map[string]*multicastInterface)
current := m.config.GetCurrent()
m.listenPort = current.LinkLocalTCPPort
m.groupAddr = "[ff02::114]:9001"
return nil
m.groupAddr, err = net.ResolveUDPAddr("udp6", GroupAddr)
return
}
// Start starts the multicast interface. This launches goroutines which will
@ -71,7 +88,7 @@ func (m *Multicast) _start() error {
return nil
}
m.log.Infoln("Starting multicast module")
addr, err := net.ResolveUDPAddr("udp", m.groupAddr)
addr, err := net.ResolveUDPAddr("udp", GroupAddr)
if err != nil {
return err
}
@ -91,7 +108,7 @@ func (m *Multicast) _start() error {
m.isOpen = true
go m.listen()
m.Act(m, m.multicastStarted)
m.Act(m, m.announce)
m.Act(m, m.monitorInterfaceChanges)
return nil
}
@ -118,9 +135,14 @@ func (m *Multicast) Stop() error {
func (m *Multicast) _stop() error {
m.log.Infoln("Stopping multicast module")
m.isOpen = false
if m.announcer != nil {
m.announcer.Stop()
}
/*
if m.monitorInterfaceChanges != nil {
m.monitorInterfaceChanges.Stop()
}
if m.sendBeacons != nil {
m.sendBeacons.Stop()
}
*/
if m.platformhandler != nil {
m.platformhandler.Stop()
}
@ -156,6 +178,83 @@ func (m *Multicast) _updateConfig(config *config.NodeConfig) {
m.log.Debugln("Reloaded multicast configuration successfully")
}
func (m *Multicast) monitorInterfaceChanges() {
interfaces := m.Interfaces()
// Look for interfaces we don't know about yet.
for name, intf := range interfaces {
if _, ok := m.listeners[name]; !ok {
// Look up interface addresses.
addrs, err := intf.Addrs()
if err != nil {
continue
}
// 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(multicastInterface, multicastInterface.announce)
m.listeners[name] = multicastInterface
m.log.Infoln("Started multicasting on", name)
break
}
}
}
// Look for interfaces we knew about but are no longer there.
for name, intf := range m.listeners {
if _, ok := interfaces[name]; !ok {
// This is a disappeared interface. Stop the announcer.
close(intf.stop)
delete(m.listeners, name)
m.log.Infoln("Stopped multicasting on", name)
}
}
// Queue the next check.
m.interfaceMonitor = time.AfterFunc(time.Second, func() {
m.Act(m, m.monitorInterfaceChanges)
})
}
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(m, 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.
@ -183,6 +282,19 @@ func (m *Multicast) Interfaces() map[string]net.Interface {
// Ignore point-to-point interfaces
continue
}
addrs, _ := iface.Addrs()
hasLLAddr := false
for _, addr := range addrs {
addrIP, _, _ := net.ParseCIDR(addr.String())
if addrIP.To4() == nil && addrIP.IsLinkLocalUnicast() {
hasLLAddr = true
break
}
}
if !hasLLAddr {
// Ignore interfaces without link-local addresses
continue
}
for _, expr := range exprs {
// Compile each regular expression
e, err := regexp.Compile(expr)
@ -198,127 +310,8 @@ func (m *Multicast) Interfaces() map[string]net.Interface {
return interfaces
}
func (m *Multicast) announce() {
groupAddr, err := net.ResolveUDPAddr("udp6", m.groupAddr)
if err != nil {
panic(err)
}
destAddr, err := net.ResolveUDPAddr("udp6", m.groupAddr)
if err != nil {
panic(err)
}
interfaces := m.Interfaces()
// 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 := 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 _, iface := range interfaces {
// Find interface addresses
addrs, err := iface.Addrs()
if err != nil {
panic(err)
}
for _, addr := range 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
}
}
m.announcer = time.AfterFunc(time.Second, func() {
m.Act(m, m.announce)
})
}
func (m *Multicast) listen() {
groupAddr, err := net.ResolveUDPAddr("udp6", m.groupAddr)
groupAddr, err := net.ResolveUDPAddr("udp6", GroupAddr)
if err != nil {
panic(err)
}