Feature: bind socket to interface by native API on Windows (#2662)

component/dialer/bind_windows.go

@@ -0,0 +1,98 @@
+package dialer
+
+import (
+	"encoding/binary"
+	"net"
+	"strings"
+	"syscall"
+	"unsafe"
+
+	"github.com/Dreamacro/clash/component/iface"
+
+	"golang.org/x/sys/windows"
+)
+
+const (
+	IP_UNICAST_IF   = 31
+	IPV6_UNICAST_IF = 31
+)
+
+type controlFn = func(network, address string, c syscall.RawConn) error
+
+func bindControl(ifaceIdx int, chain controlFn) controlFn {
+	return func(network, address string, c syscall.RawConn) (err error) {
+		defer func() {
+			if err == nil && chain != nil {
+				err = chain(network, address, c)
+			}
+		}()
+
+		ipStr, _, err := net.SplitHostPort(address)
+		if err == nil {
+			ip := net.ParseIP(ipStr)
+			if ip != nil && !ip.IsGlobalUnicast() {
+				return
+			}
+		}
+
+		var innerErr error
+		err = c.Control(func(fd uintptr) {
+			if ipStr == "" && strings.HasPrefix(network, "udp") {
+				// When listening udp ":0", we should bind socket to interface4 and interface6 at the same time
+				// and ignore the error of bind6
+				_ = bindSocketToInterface6(windows.Handle(fd), ifaceIdx)
+				innerErr = bindSocketToInterface4(windows.Handle(fd), ifaceIdx)
+				return
+			}
+			switch network {
+			case "tcp4", "udp4":
+				innerErr = bindSocketToInterface4(windows.Handle(fd), ifaceIdx)
+			case "tcp6", "udp6":
+				innerErr = bindSocketToInterface6(windows.Handle(fd), ifaceIdx)
+			}
+		})
+
+		if innerErr != nil {
+			err = innerErr
+		}
+
+		return
+	}
+}
+
+func bindSocketToInterface4(handle windows.Handle, ifaceIdx int) error {
+	// MSDN says for IPv4 this needs to be in net byte order, so that it's like an IP address with leading zeros.
+	// Ref: https://learn.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
+	var bytes [4]byte
+	binary.BigEndian.PutUint32(bytes[:], uint32(ifaceIdx))
+	index := *(*uint32)(unsafe.Pointer(&bytes[0]))
+	err := windows.SetsockoptInt(handle, windows.IPPROTO_IP, IP_UNICAST_IF, int(index))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func bindSocketToInterface6(handle windows.Handle, ifaceIdx int) error {
+	return windows.SetsockoptInt(handle, windows.IPPROTO_IPV6, IPV6_UNICAST_IF, ifaceIdx)
+}
+
+func bindIfaceToDialer(ifaceName string, dialer *net.Dialer, _ string, _ net.IP) error {
+	ifaceObj, err := iface.ResolveInterface(ifaceName)
+	if err != nil {
+		return err
+	}
+
+	dialer.Control = bindControl(ifaceObj.Index, dialer.Control)
+	return nil
+}
+
+func bindIfaceToListenConfig(ifaceName string, lc *net.ListenConfig, _, address string) (string, error) {
+	ifaceObj, err := iface.ResolveInterface(ifaceName)
+	if err != nil {
+		return "", err
+	}
+
+	lc.Control = bindControl(ifaceObj.Index, lc.Control)
+	return address, nil
+}