lib/connections: Actually fix LAN detection, for real (ref #4534)

lib/connections/lan_test.go

@@ -0,0 +1,47 @@
+// Copyright (C) 2017 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package connections
+
+import (
+	"testing"
+
+	"github.com/syncthing/syncthing/lib/config"
+)
+
+func TestIsLANHost(t *testing.T) {
+	cases := []struct {
+		addr string
+		lan  bool
+	}{
+		// loopback
+		{"127.0.0.1:22000", true},
+		{"127.0.0.1", true},
+		// local nets
+		{"10.20.30.40:22000", true},
+		{"10.20.30.40", true},
+		// neither
+		{"192.0.2.1:22000", false},
+		{"192.0.2.1", false},
+		// doesn't resolve
+		{"[banana::phone]:hello", false},
+		{"„‹›fl´fi·‰ˇ¨Á˝", false},
+	}
+
+	cfg := config.Wrap("/dev/null", config.Configuration{
+		Options: config.OptionsConfiguration{
+			AlwaysLocalNets: []string{"10.20.30.0/24"},
+		},
+	})
+	s := &Service{cfg: cfg}
+
+	for _, tc := range cases {
+		res := s.isLANHost(tc.addr)
+		if res != tc.lan {
+			t.Errorf("isLANHost(%q) => %v, expected %v", tc.addr, res, tc.lan)
+		}
+	}
+}