Add net control funcs

common/control/bind_linux.go

@@ -0,0 +1,17 @@
+package control
+
+import (
+	"syscall"
+
+	"github.com/sagernet/sing/common"
+)
+
+func BindToInterface(interfaceName string) Func {
+	return func(network, address string, conn syscall.RawConn) error {
+		var innerErr error
+		err := conn.Control(func(fd uintptr) {
+			innerErr = syscall.BindToDevice(int(fd), interfaceName)
+		})
+		return common.AnyError(innerErr, err)
+	}
+}

common/control/bind_other.go

@@ -0,0 +1,7 @@
+//go:build !linux
+
+package control
+
+func BindToInterface(interfaceName string) Func {
+	return nil
+}

common/control/interface.go

@@ -0,0 +1,21 @@
+package control
+
+import (
+	"syscall"
+)
+
+type Func = func(network, address string, conn syscall.RawConn) error
+
+func Append(oldFunc Func, newFunc Func) Func {
+	if oldFunc == nil {
+		return newFunc
+	} else if newFunc == nil {
+		return oldFunc
+	}
+	return func(network, address string, conn syscall.RawConn) error {
+		if err := oldFunc(network, address, conn); err != nil {
+			return err
+		}
+		return newFunc(network, address, conn)
+	}
+}

common/control/mark_linux.go

@@ -0,0 +1,17 @@
+package control
+
+import (
+	"syscall"
+
+	"github.com/sagernet/sing/common"
+)
+
+func RoutingMark(mark int) Func {
+	return func(network, address string, conn syscall.RawConn) error {
+		var innerErr error
+		err := conn.Control(func(fd uintptr) {
+			innerErr = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_MARK, mark)
+		})
+		return common.AnyError(innerErr, err)
+	}
+}

common/control/mark_other.go

@@ -0,0 +1,7 @@
+//go:build !linux
+
+package control
+
+func RoutingMark(mark int) Func {
+	return nil
+}

common/control/reuse_linux.go

@@ -0,0 +1,21 @@
+package control
+
+import (
+	"syscall"
+
+	"github.com/sagernet/sing/common"
+)
+
+func ReuseAddr() Func {
+	return func(network, address string, conn syscall.RawConn) error {
+		var innerErr error
+		err := conn.Control(func(fd uintptr) {
+			const SO_REUSEPORT = 0xf
+			innerErr = common.AnyError(
+				syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1),
+				syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, SO_REUSEPORT, 1),
+			)
+		})
+		return common.AnyError(innerErr, err)
+	}
+}

common/control/reuse_other.go

@@ -0,0 +1,7 @@
+//go:build !linux
+
+package control
+
+func ReuseAddr() Func {
+	return nil
+}