Add unbind control

Author: nekohasekai

common/control/bind.go

@@ -24,6 +24,12 @@ func BindToInterfaceFunc(finder InterfaceFinder, block func(network string, addr
 	}
 }
 
+func UnbindFromInterface() Func {
+	return func(network, address string, conn syscall.RawConn) error {
+		return unbindFromInterface(conn, network, address)
+	}
+}
+
 func BindToInterface0(finder InterfaceFinder, conn syscall.RawConn, network string, address string, interfaceName string, interfaceIndex int, preferInterfaceName bool) error {
 	if interfaceName == "" && interfaceIndex == -1 {
 		return E.New("interface not found: ", interfaceName)

common/control/bind_darwin.go

@@ -27,3 +27,7 @@ func bindToInterface(conn syscall.RawConn, network string, address string, finde
 		}
 	})
 }
+
+func unbindFromInterface(conn syscall.RawConn, network string, address string) error {
+	return bindToInterface(conn, network, address, nil, "", 0, false)
+}

common/control/bind_linux.go

@@ -40,3 +40,19 @@ func bindToInterface(conn syscall.RawConn, network string, address string, finde
 		return unix.BindToDevice(int(fd), interfaceName)
 	})
 }
+
+func unbindFromInterface(conn syscall.RawConn, network string, address string) error {
+	return Raw(conn, func(fd uintptr) error {
+		if !ifIndexDisabled.Load() {
+			err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_BINDTOIFINDEX, 0)
+			if err == nil {
+				return nil
+			} else if E.IsMulti(err, unix.ENOPROTOOPT, unix.EINVAL) {
+				ifIndexDisabled.Store(true)
+			} else {
+				return err
+			}
+		}
+		return unix.BindToDevice(int(fd), "")
+	})
+}

common/control/bind_other.go

@@ -7,3 +7,7 @@ import "syscall"
 func bindToInterface(conn syscall.RawConn, network string, address string, finder InterfaceFinder, interfaceName string, interfaceIndex int, preferInterfaceName bool) error {
 	return nil
 }
+
+func unbindFromInterface(conn syscall.RawConn, network string, address string) error {
+	return nil
+}

common/control/bind_windows.go

@@ -40,6 +40,10 @@ func bindToInterface(conn syscall.RawConn, network string, address string, finde
 	})
 }
 
+func unbindFromInterface(conn syscall.RawConn, network string, address string) error {
+	return bindToInterface(conn, network, address, nil, "", 0, false)
+}
+
 const (
 	IP_UNICAST_IF   = 31
 	IPV6_UNICAST_IF = 31