net/portmapper: disable UPnP on iOS for now

Updates #2495

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

net/portmapper/disabled_stubs.go

@@ -0,0 +1,29 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ios
+// (https://github.com/tailscale/tailscale/issues/2495)
+
+package portmapper
+
+import (
+	"context"
+
+	"inet.af/netaddr"
+)
+
+type upnpClient interface{}
+
+func getUPnPClient(ctx context.Context, gw netaddr.IP) (upnpClient, error) {
+	return nil, nil
+}
+
+func (c *Client) getUPnPPortMapping(
+	ctx context.Context,
+	gw netaddr.IP,
+	internal netaddr.IPPort,
+	prevPort uint16,
+) (external netaddr.IPPort, ok bool) {
+	return netaddr.IPPort{}, false
+}

net/portmapper/upnp.go

@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !ios
+// (https://github.com/tailscale/tailscale/issues/2495)
+
 package portmapper
 
 import (