Implement route rules

adapter/route/rule_network.go

@@ -0,0 +1,23 @@
+package route
+
+import (
+	"github.com/sagernet/sing-box/adapter"
+)
+
+var _ RuleItem = (*NetworkItem)(nil)
+
+type NetworkItem struct {
+	network string
+}
+
+func NewNetworkItem(network string) *NetworkItem {
+	return &NetworkItem{network}
+}
+
+func (r *NetworkItem) Match(metadata *adapter.InboundContext) bool {
+	return r.network == metadata.Network
+}
+
+func (r *NetworkItem) String() string {
+	return "network=" + r.network
+}