change multicast config format

src/config/config.go

@@ -31,7 +31,7 @@ type NodeConfig struct {
 	InterfacePeers      map[string][]string        `comment:"List of connection strings for outbound peer connections in URI format,\narranged by source interface, e.g. { \"eth0\": [ tls://a.b.c.d:e ] }.\nNote that SOCKS peerings will NOT be affected by this option and should\ngo in the \"Peers\" section instead."`
 	Listen              []string                   `comment:"Listen addresses for incoming connections. You will need to add\nlisteners in order to accept incoming peerings from non-local nodes.\nMulticast peer discovery will work regardless of any listeners set\nhere. Each listener should be specified in URI format as above, e.g.\ntls://0.0.0.0:0 or tls://[::]:0 to listen on all interfaces."`
 	AdminListen         string                     `comment:"Listen address for admin connections. Default is to listen for local\nconnections either on TCP/9001 or a UNIX socket depending on your\nplatform. Use this value for yggdrasilctl -endpoint=X. To disable\nthe admin socket, use the value \"none\" instead."`
-	MulticastInterfaces []string               `comment:"Regular expressions for which interfaces multicast peer discovery\nshould be enabled on. If none specified, multicast peer discovery is\ndisabled. The default value is .* which uses all interfaces."`
+	MulticastInterfaces []MulticastInterfaceConfig `comment:"Regular expressions for which interfaces multicast peer discovery\nshould be enabled on. If none specified, multicast peer discovery is\ndisabled. The default value is .* which uses all interfaces."`
 	AllowedPublicKeys   []string                   `comment:"List of peer public keys to allow incoming peering connections\nfrom. If left empty/undefined then all connections will be allowed\nby default. This does not affect outgoing peerings, nor does it\naffect link-local peers discovered via multicast."`
 	PublicKey           string                     `comment:"Your public key. Your peers may ask you for this to put\ninto their AllowedPublicKeys configuration."`
 	PrivateKey          string                     `comment:"Your private key. DO NOT share this with anyone!"`
@@ -42,6 +42,12 @@ type NodeConfig struct {
 	NodeInfo            map[string]interface{}     `comment:"Optional node info. This must be a { \"key\": \"value\", ... } map\nor set as null. This is entirely optional but, if set, is visible\nto the whole network on request."`
 }
 
+type MulticastInterfaceConfig struct {
+	Regex    string
+	Incoming bool
+	Outgoing bool
+}
+
 // NewSigningKeys replaces the signing keypair in the NodeConfig with a new
 // signing keypair. The signing keys are used by the switch to derive the
 // structure of the spanning tree.

src/defaults/defaults.go

@@ -2,6 +2,8 @@ package defaults
 
 import "github.com/yggdrasil-network/yggdrasil-go/src/config"
 
+type MulticastInterfaceConfig = config.MulticastInterfaceConfig
+
 // Defines which parameters are expected by default for configuration on a
 // specific platform. These values are populated in the relevant defaults_*.go
 // for the platform being targeted. They must be set.
@@ -13,7 +15,7 @@ type platformDefaultParameters struct {
 	DefaultConfigFile string
 
 	// Multicast interfaces
-	DefaultMulticastInterfaces []string
+	DefaultMulticastInterfaces []MulticastInterfaceConfig
 
 	// TUN/TAP
 	MaximumIfMTU  uint64

src/defaults/defaults_darwin.go

@@ -13,9 +13,9 @@ func GetDefaults() platformDefaultParameters {
 		DefaultConfigFile: "/etc/yggdrasil.conf",
 
 		// Multicast interfaces
-		DefaultMulticastInterfaces: []string{
-			"en.*",
-			"bridge.*",
+		DefaultMulticastInterfaces: []MulticastInterfaceConfig{
+			{Regex: "en.*", Incoming: true, Outgoing: true},
+			{Regex: "bridge.*", Incoming: true, Outgoing: true},
 		},
 
 		// TUN/TAP

src/defaults/defaults_freebsd.go

@@ -13,8 +13,8 @@ func GetDefaults() platformDefaultParameters {
 		DefaultConfigFile: "/usr/local/etc/yggdrasil.conf",
 
 		// Multicast interfaces
-		DefaultMulticastInterfaces: []string{
-			".*",
+		DefaultMulticastInterfaces: []MulticastInterfaceConfig{
+			{Regex: ".*", Incoming: true, Outgoing: true},
 		},
 
 		// TUN/TAP

src/defaults/defaults_linux.go

@@ -13,8 +13,8 @@ func GetDefaults() platformDefaultParameters {
 		DefaultConfigFile: "/etc/yggdrasil.conf",
 
 		// Multicast interfaces
-		DefaultMulticastInterfaces: []string{
-			".*",
+		DefaultMulticastInterfaces: []MulticastInterfaceConfig{
+			{Regex: ".*", Incoming: true, Outgoing: true},
 		},
 
 		// TUN/TAP

src/defaults/defaults_openbsd.go

@@ -13,8 +13,8 @@ func GetDefaults() platformDefaultParameters {
 		DefaultConfigFile: "/etc/yggdrasil.conf",
 
 		// Multicast interfaces
-		DefaultMulticastInterfaces: []string{
-			".*",
+		DefaultMulticastInterfaces: []MulticastInterfaceConfig{
+			{Regex: ".*", Incoming: true, Outgoing: true},
 		},
 
 		// TUN/TAP

src/defaults/defaults_other.go

@@ -13,8 +13,8 @@ func GetDefaults() platformDefaultParameters {
 		DefaultConfigFile: "/etc/yggdrasil.conf",
 
 		// Multicast interfaces
-		DefaultMulticastInterfaces: []string{
-			".*",
+		DefaultMulticastInterfaces: []MulticastInterfaceConfig{
+			{Regex: ".*", Incoming: true, Outgoing: true},
 		},
 
 		// TUN/TAP

src/defaults/defaults_windows.go

@@ -13,8 +13,8 @@ func GetDefaults() platformDefaultParameters {
 		DefaultConfigFile: "C:\\Program Files\\Yggdrasil\\yggdrasil.conf",
 
 		// Multicast interfaces
-		DefaultMulticastInterfaces: []string{
-			".*",
+		DefaultMulticastInterfaces: []MulticastInterfaceConfig{
+			{Regex: ".*", Incoming: true, Outgoing: true},
 		},
 
 		// TUN/TAP

src/multicast/multicast.go

@@ -40,6 +40,8 @@ type Multicast struct {
 type interfaceInfo struct {
 	iface    net.Interface
 	addrs    []net.Addr
+	incoming bool
+	outgoing bool
 }
 
 type listenerInfo struct {
@@ -136,18 +138,16 @@ func (m *Multicast) _stop() error {
 }
 
 func (m *Multicast) _updateInterfaces() {
-	interfaces := make(map[string]interfaceInfo)
-	intfs := m.getAllowedInterfaces()
-	for _, intf := range intfs {
-		addrs, err := intf.Addrs()
+	interfaces := m.getAllowedInterfaces()
+	for name, info := range interfaces {
+		addrs, err := info.iface.Addrs()
 		if err != nil {
-			m.log.Warnf("Failed up get addresses for interface %s: %s", intf.Name, err)
+			m.log.Warnf("Failed up get addresses for interface %s: %s", name, err)
+			delete(interfaces, name)
 			continue
 		}
-		interfaces[intf.Name] = interfaceInfo{
-			iface: intf,
-			addrs: addrs,
-		}
+		info.addrs = addrs
+		interfaces[name] = info
 	}
 	m._interfaces = interfaces
 }
@@ -163,10 +163,10 @@ func (m *Multicast) Interfaces() map[string]net.Interface {
 }
 
 // getAllowedInterfaces returns the currently known/enabled multicast interfaces.
-func (m *Multicast) getAllowedInterfaces() map[string]net.Interface {
-	interfaces := make(map[string]net.Interface)
+func (m *Multicast) getAllowedInterfaces() map[string]interfaceInfo {
+	interfaces := make(map[string]interfaceInfo)
 	// Get interface expressions from config
-	exprs := m.config.MulticastInterfaces
+	ifcfgs := m.config.MulticastInterfaces
 	// Ask the system for network interfaces
 	allifaces, err := net.Interfaces()
 	if err != nil {
@@ -188,15 +188,23 @@ func (m *Multicast) getAllowedInterfaces() map[string]net.Interface {
 			// Ignore point-to-point interfaces
 			continue
 		}
-		for _, expr := range exprs {
+		for _, ifcfg := range ifcfgs {
 			// Compile each regular expression
-			e, err := regexp.Compile(expr)
+			e, err := regexp.Compile(ifcfg.Regex)
 			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
+				if ifcfg.Incoming || ifcfg.Outgoing {
+					info := interfaceInfo{
+						iface:    iface,
+						incoming: ifcfg.Incoming,
+						outgoing: ifcfg.Outgoing,
+					}
+					interfaces[iface.Name] = info
+				}
+				break
 			}
 		}
 	}
@@ -272,8 +280,13 @@ func (m *Multicast) _announce() {
 			if !addrIP.IsLinkLocalUnicast() {
 				continue
 			}
-			// Join the multicast group
+			if info.outgoing {
+				// Join the multicast group, so we can listen for advertisements to open outgoing connections
 				_ = m.sock.JoinGroup(&iface, groupAddr)
+			}
+			if !info.incoming {
+				break // Don't send multicast advertisements if we don't accept incoming connections
+			}
 			// 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 {
@@ -378,7 +391,7 @@ func (m *Multicast) listen() {
 		phony.Block(m, func() {
 			interfaces = m._interfaces
 		})
-		if _, ok := interfaces[from.Zone]; ok {
+		if info, ok := interfaces[from.Zone]; ok && info.outgoing {
 			addr.Zone = ""
 			pin := fmt.Sprintf("/?key=%s", hex.EncodeToString(key))
 			u, err := url.Parse("tls://" + addr.String() + pin)