Proxy: Add TUN inbound for Windows & Linux, including Android (#5464)

* Proxy: Implement tun raw network interface inbound support for Linux

* Proxy: Tun. Include "android" as build condition for build of tun_default implementation

* Proxy: Tun. Add .Close() cleanup calls to Handler.Init() where needed

* Proxy: Add Tun for Android

* Proxy: Tun. Implement Windows support

---------

Co-authored-by: yuhan6665 <1588741+yuhan6665@users.noreply.github.com>

infra/conf/tun.go

@@ -0,0 +1,30 @@
+package conf
+
+import (
+	"github.com/xtls/xray-core/proxy/tun"
+	"google.golang.org/protobuf/proto"
+)
+
+type TunConfig struct {
+	Name      string `json:"name"`
+	MTU       uint32 `json:"MTU"`
+	UserLevel uint32 `json:"userLevel"`
+}
+
+func (v *TunConfig) Build() (proto.Message, error) {
+	config := &tun.Config{
+		Name:      v.Name,
+		MTU:       v.MTU,
+		UserLevel: v.UserLevel,
+	}
+
+	if v.Name == "" {
+		config.Name = "xray0"
+	}
+
+	if v.MTU == 0 {
+		config.MTU = 1500
+	}
+
+	return config, nil
+}

infra/conf/xray.go

@@ -28,6 +28,7 @@ var (
 		"vmess":         func() interface{} { return new(VMessInboundConfig) },
 		"trojan":        func() interface{} { return new(TrojanServerConfig) },
 		"wireguard":     func() interface{} { return &WireGuardConfig{IsClient: false} },
+		"tun":           func() interface{} { return new(TunConfig) },
 	}, "protocol", "settings")
 
 	outboundConfigLoader = NewJSONConfigLoader(ConfigCreatorCache{