control: Refactor interface finder

common/cond.go

@@ -157,6 +157,18 @@ func IndexIndexed[T any](arr []T, block func(index int, it T) bool) int {
 	return -1
 }
 
+func Equal[S ~[]E, E comparable](s1, s2 S) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i := range s1 {
+		if s1[i] != s2[i] {
+			return false
+		}
+	}
+	return true
+}
+
 //go:norace
 func Dup[T any](obj T) T {
 	pointer := uintptr(unsafe.Pointer(&obj))
@@ -268,6 +280,14 @@ func Reverse[T any](arr []T) []T {
 	return arr
 }
 
+func ReverseMap[K comparable, V comparable](m map[K]V) map[V]K {
+	ret := make(map[V]K, len(m))
+	for k, v := range m {
+		ret[v] = k
+	}
+	return ret
+}
+
 func Done(ctx context.Context) bool {
 	select {
 	case <-ctx.Done():
@@ -362,24 +382,3 @@ func Close(closers ...any) error {
 	}
 	return retErr
 }
-
-// Deprecated: wtf is this?
-type Starter interface {
-	Start() error
-}
-
-// Deprecated: wtf is this?
-func Start(starters ...any) error {
-	for _, rawStarter := range starters {
-		if rawStarter == nil {
-			continue
-		}
-		if starter, isStarter := rawStarter.(Starter); isStarter {
-			err := starter.Start()
-			if err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}

common/control/bind_darwin.go

@@ -9,15 +9,15 @@ import (
 
 func bindToInterface(conn syscall.RawConn, network string, address string, finder InterfaceFinder, interfaceName string, interfaceIndex int, preferInterfaceName bool) error {
 	return Raw(conn, func(fd uintptr) error {
-		var err error
 		if interfaceIndex == -1 {
 			if finder == nil {
 				return os.ErrInvalid
 			}
-			interfaceIndex, err = finder.InterfaceIndexByName(interfaceName)
+			iif, err := finder.ByName(interfaceName)
 			if err != nil {
 				return err
 			}
+			interfaceIndex = iif.Index
 		}
 		switch network {
 		case "tcp6", "udp6":

common/control/bind_finder.go

@@ -3,21 +3,57 @@ package control
 import (
 	"net"
 	"net/netip"
+	"unsafe"
+
+	"github.com/sagernet/sing/common"
+	M "github.com/sagernet/sing/common/metadata"
 )
 
 type InterfaceFinder interface {
 	Update() error
 	Interfaces() []Interface
-	InterfaceIndexByName(name string) (int, error)
-	InterfaceNameByIndex(index int) (string, error)
-	InterfaceByAddr(addr netip.Addr) (*Interface, error)
+	ByName(name string) (*Interface, error)
+	ByIndex(index int) (*Interface, error)
+	ByAddr(addr netip.Addr) (*Interface, error)
 }
 
 type Interface struct {
 	Index        int
 	MTU          int
 	Name         string
-	Addresses    []netip.Prefix
 	HardwareAddr net.HardwareAddr
 	Flags        net.Flags
+	Addresses    []netip.Prefix
+}
+
+func (i Interface) Equals(other Interface) bool {
+	return i.Index == other.Index &&
+		i.MTU == other.MTU &&
+		i.Name == other.Name &&
+		common.Equal(i.HardwareAddr, other.HardwareAddr) &&
+		i.Flags == other.Flags &&
+		common.Equal(i.Addresses, other.Addresses)
+}
+
+func (i Interface) NetInterface() net.Interface {
+	return *(*net.Interface)(unsafe.Pointer(&i))
+}
+
+func InterfaceFromNet(iif net.Interface) (Interface, error) {
+	ifAddrs, err := iif.Addrs()
+	if err != nil {
+		return Interface{}, err
+	}
+	return InterfaceFromNetAddrs(iif, common.Map(ifAddrs, M.PrefixFromNet)), nil
+}
+
+func InterfaceFromNetAddrs(iif net.Interface, addresses []netip.Prefix) Interface {
+	return Interface{
+		Index:        iif.Index,
+		MTU:          iif.MTU,
+		Name:         iif.Name,
+		HardwareAddr: iif.HardwareAddr,
+		Flags:        iif.Flags,
+		Addresses:    addresses,
+	}
 }

common/control/bind_finder_default.go

@@ -3,11 +3,8 @@ package control
 import (
 	"net"
 	"net/netip"
-	_ "unsafe"
 
-	"github.com/sagernet/sing/common"
 	E "github.com/sagernet/sing/common/exceptions"
-	M "github.com/sagernet/sing/common/metadata"
 )
 
 var _ InterfaceFinder = (*DefaultInterfaceFinder)(nil)
@@ -27,18 +24,12 @@ func (f *DefaultInterfaceFinder) Update() error {
 	}
 	interfaces := make([]Interface, 0, len(netIfs))
 	for _, netIf := range netIfs {
-		ifAddrs, err := netIf.Addrs()
+		var iif Interface
+		iif, err = InterfaceFromNet(netIf)
 		if err != nil {
 			return err
 		}
-		interfaces = append(interfaces, Interface{
-			Index:        netIf.Index,
-			MTU:          netIf.MTU,
-			Name:         netIf.Name,
-			Addresses:    common.Map(ifAddrs, M.PrefixFromNet),
-			HardwareAddr: netIf.HardwareAddr,
-			Flags:        netIf.Flags,
-		})
+		interfaces = append(interfaces, iif)
 	}
 	f.interfaces = interfaces
 	return nil
@@ -52,46 +43,41 @@ func (f *DefaultInterfaceFinder) Interfaces() []Interface {
 	return f.interfaces
 }
 
-func (f *DefaultInterfaceFinder) InterfaceIndexByName(name string) (int, error) {
+func (f *DefaultInterfaceFinder) ByName(name string) (*Interface, error) {
 	for _, netInterface := range f.interfaces {
 		if netInterface.Name == name {
-			return netInterface.Index, nil
+			return &netInterface, nil
 		}
 	}
-	netInterface, err := net.InterfaceByName(name)
-	if err != nil {
-		return 0, err
+	_, err := net.InterfaceByName(name)
+	if err == nil {
+		err = f.Update()
+		if err != nil {
+			return nil, err
+		}
+		return f.ByName(name)
 	}
-	f.Update()
-	return netInterface.Index, nil
+	return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: &net.IPAddr{IP: nil}, Err: E.New("no such network interface")}
 }
 
-func (f *DefaultInterfaceFinder) InterfaceNameByIndex(index int) (string, error) {
+func (f *DefaultInterfaceFinder) ByIndex(index int) (*Interface, error) {
 	for _, netInterface := range f.interfaces {
 		if netInterface.Index == index {
-			return netInterface.Name, nil
+			return &netInterface, nil
 		}
 	}
-	netInterface, err := net.InterfaceByIndex(index)
-	if err != nil {
-		return "", err
+	_, err := net.InterfaceByIndex(index)
+	if err == nil {
+		err = f.Update()
+		if err != nil {
+			return nil, err
+		}
+		return f.ByIndex(index)
 	}
-	f.Update()
-	return netInterface.Name, nil
+	return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: &net.IPAddr{IP: nil}, Err: E.New("no such network interface")}
 }
 
-func (f *DefaultInterfaceFinder) InterfaceByAddr(addr netip.Addr) (*Interface, error) {
-	for _, netInterface := range f.interfaces {
-		for _, prefix := range netInterface.Addresses {
-			if prefix.Contains(addr) {
-				return &netInterface, nil
-			}
-		}
-	}
-	err := f.Update()
-	if err != nil {
-		return nil, err
-	}
+func (f *DefaultInterfaceFinder) ByAddr(addr netip.Addr) (*Interface, error) {
 	for _, netInterface := range f.interfaces {
 		for _, prefix := range netInterface.Addresses {
 			if prefix.Contains(addr) {

common/control/bind_linux.go

@@ -19,11 +19,11 @@ func bindToInterface(conn syscall.RawConn, network string, address string, finde
 				if interfaceName == "" {
 					return os.ErrInvalid
 				}
-				var err error
-				interfaceIndex, err = finder.InterfaceIndexByName(interfaceName)
+				iif, err := finder.ByName(interfaceName)
 				if err != nil {
 					return err
 				}
+				interfaceIndex = iif.Index
 			}
 			err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_BINDTOIFINDEX, interfaceIndex)
 			if err == nil {

common/control/bind_windows.go

@@ -11,19 +11,19 @@ import (
 
 func bindToInterface(conn syscall.RawConn, network string, address string, finder InterfaceFinder, interfaceName string, interfaceIndex int, preferInterfaceName bool) error {
 	return Raw(conn, func(fd uintptr) error {
-		var err error
 		if interfaceIndex == -1 {
 			if finder == nil {
 				return os.ErrInvalid
 			}
-			interfaceIndex, err = finder.InterfaceIndexByName(interfaceName)
+			iif, err := finder.ByName(interfaceName)
 			if err != nil {
 				return err
 			}
+			interfaceIndex = iif.Index
 		}
 		handle := syscall.Handle(fd)
 		if M.ParseSocksaddr(address).AddrString() == "" {
-			err = bind4(handle, interfaceIndex)
+			err := bind4(handle, interfaceIndex)
 			if err != nil {
 				return err
 			}