feat: add inbound-mptcp for listeners

adapter/inbound/listen.go

@@ -17,6 +17,10 @@ func SetTfo(open bool) {
 	lc.DisableTFO = !open
 }
 
+func SetMPTCP(open bool) {
+	setMultiPathTCP(&lc.ListenConfig, open)
+}
+
 func ListenContext(ctx context.Context, network, address string) (net.Listener, error) {
 	return lc.Listen(ctx, network, address)
 }

adapter/inbound/mptcp_go120.go

@@ -0,0 +1,10 @@
+//go:build !go1.21
+
+package inbound
+
+import "net"
+
+const multipathTCPAvailable = false
+
+func setMultiPathTCP(listenConfig *net.ListenConfig, open bool) {
+}

adapter/inbound/mptcp_go121.go

@@ -0,0 +1,11 @@
+//go:build go1.21
+
+package inbound
+
+import "net"
+
+const multipathTCPAvailable = true
+
+func setMultiPathTCP(listenConfig *net.ListenConfig, open bool) {
+	listenConfig.SetMultipathTCP(open)
+}