Add network_[type/is_expensive/is_constrained] rule items

route/rule/rule_item_network_is_expensive.go

@@ -0,0 +1,29 @@
+package rule
+
+import (
+	"github.com/sagernet/sing-box/adapter"
+)
+
+var _ RuleItem = (*NetworkIsExpensiveItem)(nil)
+
+type NetworkIsExpensiveItem struct {
+	networkManager adapter.NetworkManager
+}
+
+func NewNetworkIsExpensiveItem(networkManager adapter.NetworkManager) *NetworkIsExpensiveItem {
+	return &NetworkIsExpensiveItem{
+		networkManager: networkManager,
+	}
+}
+
+func (r *NetworkIsExpensiveItem) Match(metadata *adapter.InboundContext) bool {
+	networkInterface := r.networkManager.DefaultNetworkInterface()
+	if networkInterface == nil {
+		return false
+	}
+	return networkInterface.Expensive
+}
+
+func (r *NetworkIsExpensiveItem) String() string {
+	return "network_is_expensive=true"
+}