Fix(socks5): fully udp associate support (#233)

tunnel/session.go

@@ -0,0 +1,22 @@
+package tunnel
+
+import (
+	"sync"
+	"time"
+
+	nat "github.com/Dreamacro/clash/component/nat-table"
+)
+
+var (
+	natTable *nat.Table
+	natOnce  sync.Once
+
+	natTimeout = 120 * time.Second
+)
+
+func NATInstance() *nat.Table {
+	natOnce.Do(func() {
+		natTable = nat.New(natTimeout)
+	})
+	return natTable
+}