Subscribe to link changes from netlink

src/multicast/interfaces_linux.go

@@ -0,0 +1,7 @@
+// +build linux
+
+package multicast
+
+func (m *Multicast) _updateInterfaces() {
+	return
+}

src/multicast/interfaces_other.go

@@ -0,0 +1,65 @@
+// +build !linux
+
+package multicast
+
+import (
+	"net"
+	"regexp"
+)
+
+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,
+		}
+	}
+	m._interfaces = interfaces
+}
+
+// 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()
+	exprs := current.MulticastInterfaces
+	// Ask the system for network interfaces
+	allifaces, err := net.Interfaces()
+	if err != nil {
+		panic(err)
+	}
+	// Work out which interfaces to announce on
+	for _, iface := range allifaces {
+		if iface.Flags&net.FlagUp == 0 {
+			// Ignore interfaces that are down
+			continue
+		}
+		if iface.Flags&net.FlagMulticast == 0 {
+			// Ignore non-multicast interfaces
+			continue
+		}
+		if iface.Flags&net.FlagPointToPoint != 0 {
+			// Ignore point-to-point interfaces
+			continue
+		}
+		for _, expr := range exprs {
+			// Compile each regular expression
+			e, err := regexp.Compile(expr)
+			if err != nil {
+				panic(err)
+			}
+			// Does the interface match the regular expression? Store it if so
+			if e.MatchString(iface.Name) {
+				interfaces[iface.Name] = iface
+			}
+		}
+	}
+	return interfaces
+}

src/multicast/multicast.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"fmt"
 	"net"
-	"regexp"
 	"time"
 
 	"github.com/Arceliar/phony"
@@ -155,23 +154,6 @@ func (m *Multicast) _updateConfig(config *config.NodeConfig) {
 	m.log.Debugln("Reloaded multicast configuration successfully")
 }
 
-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,
-		}
-	}
-	m._interfaces = interfaces
-}
-
 func (m *Multicast) Interfaces() map[string]net.Interface {
 	interfaces := make(map[string]net.Interface)
 	phony.Block(m, func() {
@@ -182,46 +164,6 @@ func (m *Multicast) Interfaces() map[string]net.Interface {
 	return interfaces
 }
 
-// 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()
-	exprs := current.MulticastInterfaces
-	// Ask the system for network interfaces
-	allifaces, err := net.Interfaces()
-	if err != nil {
-		panic(err)
-	}
-	// Work out which interfaces to announce on
-	for _, iface := range allifaces {
-		if iface.Flags&net.FlagUp == 0 {
-			// Ignore interfaces that are down
-			continue
-		}
-		if iface.Flags&net.FlagMulticast == 0 {
-			// Ignore non-multicast interfaces
-			continue
-		}
-		if iface.Flags&net.FlagPointToPoint != 0 {
-			// Ignore point-to-point interfaces
-			continue
-		}
-		for _, expr := range exprs {
-			// Compile each regular expression
-			e, err := regexp.Compile(expr)
-			if err != nil {
-				panic(err)
-			}
-			// Does the interface match the regular expression? Store it if so
-			if e.MatchString(iface.Name) {
-				interfaces[iface.Name] = iface
-			}
-		}
-	}
-	return interfaces
-}
-
 func (m *Multicast) _announce() {
 	if !m.isOpen {
 		return

src/multicast/multicast_linux.go

@@ -0,0 +1,99 @@
+// +build linux
+
+package multicast
+
+import (
+	"fmt"
+	"net"
+	"regexp"
+	"syscall"
+
+	"github.com/vishvananda/netlink"
+	"golang.org/x/sys/unix"
+)
+
+func (m *Multicast) _multicastStarted() {
+	linkChanges := make(chan netlink.LinkUpdate)
+	addrChanges := make(chan netlink.AddrUpdate)
+
+	linkClose := make(chan struct{})
+	addrClose := make(chan struct{})
+
+	if err := netlink.LinkSubscribe(linkChanges, linkClose); err != nil {
+		panic(err)
+	}
+
+	if err := netlink.AddrSubscribe(addrChanges, addrClose); err != nil {
+		panic(err)
+	}
+
+	fmt.Println("Listening for netlink changes")
+
+	go func() {
+		defer fmt.Println("No longer listening for netlink changes")
+		for {
+			select {
+			case change := <-linkChanges:
+				attrs := change.Attrs()
+				add := true
+				add = add && attrs.Flags&net.FlagUp == 1
+				add = add && attrs.Flags&net.FlagMulticast == 1
+				add = add && attrs.Flags&net.FlagPointToPoint == 0
+
+				match := false
+				for _, expr := range exprs {
+					e, err := regexp.Compile(expr)
+					if err != nil {
+						panic(err)
+					}
+					if e.MatchString(attrs.Name) {
+						match = true
+						break
+					}
+				}
+				add = add && match
+
+				if add {
+					m.Act(nil, func() {
+						fmt.Println("Link added:", attrs.Name)
+						if intf, err := net.InterfaceByName(attrs.Name); err == nil {
+							m._interfaces[attrs.Name] = intf
+						}
+					})
+				} else {
+					m.Act(nil, func() {
+						fmt.Println("Link removed:", attrs.Name)
+						delete(m._interfaces, attrs.Name)
+					})
+				}
+
+			case change := <-addrChanges:
+				m.Act(nil, func() {
+					fmt.Println("Addr changed:", change)
+				})
+
+			case <-linkClose:
+				return
+
+			case <-addrClose:
+				return
+			}
+		}
+	}()
+}
+
+func (m *Multicast) multicastReuse(network string, address string, c syscall.RawConn) error {
+	var control error
+	var reuseport error
+
+	control = c.Control(func(fd uintptr) {
+		reuseport = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
+	})
+
+	switch {
+	case reuseport != nil:
+		return reuseport
+	default:
+		return control
+	}
+}

src/multicast/multicast_unix.go

@@ -1,9 +1,12 @@
-// +build linux netbsd freebsd openbsd dragonflybsd
+// +build netbsd freebsd openbsd dragonflybsd
 
 package multicast
 
-import "syscall"
-import "golang.org/x/sys/unix"
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
 
 func (m *Multicast) _multicastStarted() {