hostinfo, ipn/ipnlocal: add SetPackage, remove ipnlocal hacks

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

hostinfo/hostinfo.go

@@ -48,6 +48,9 @@ func getOSVersion() string {
 }
 
 func packageType() string {
+	if v, _ := packagingType.Load().(string); v != "" {
+		return v
+	}
 	switch runtime.GOOS {
 	case "windows":
 		if _, err := os.Stat(`C:\ProgramData\chocolatey\lib\tailscale`); err == nil {
@@ -95,6 +98,7 @@ func GetEnvType() EnvType {
 var (
 	deviceModelAtomic atomic.Value // of string
 	osVersionAtomic   atomic.Value // of string
+	packagingType     atomic.Value // of string
 )
 
 // SetDeviceModel sets the device model for use in Hostinfo updates.
@@ -103,6 +107,11 @@ func SetDeviceModel(model string) { deviceModelAtomic.Store(model) }
 // SetOSVersion sets the OS version.
 func SetOSVersion(v string) { osVersionAtomic.Store(v) }
 
+// SetPackage sets the packaging type for the app.
+// This is currently (2021-10-05) only used by Android,
+// set to "nogoogle" for the F-Droid build.
+func SetPackage(v string) { packagingType.Store(v) }
+
 func deviceModel() string {
 	s, _ := deviceModelAtomic.Load().(string)
 	return s

ipn/ipnlocal/local.go

@@ -2277,20 +2277,8 @@ func applyPrefsToHostinfo(hi *tailcfg.Hostinfo, prefs *ipn.Prefs) {
 	}
 	if v := prefs.OSVersion; v != "" && hi.OSVersion == "" {
 		hi.OSVersion = v
-
-		// The Android app annotates when Google Play Services
-		// aren't available by tacking on a string to the
-		// OSVersion. Promote that to the Hostinfo.Package
-		// field instead, rather than adding a new pref, as
-		// this applyPrefsToHostinfo mechanism is mostly
-		// abused currently. TODO(bradfitz): instead let
-		// frontends update Hostinfo, without using Prefs.
-		if runtime.GOOS == "android" && strings.HasSuffix(v, " [nogoogle]") {
-			hi.Package = "nogoogle"
-			hi.OSVersion = strings.TrimSuffix(v, " [nogoogle]")
-		}
 	}
-	if m := prefs.DeviceModel; m != "" {
+	if m := prefs.DeviceModel; m != "" && hi.DeviceModel == "" {
 		hi.DeviceModel = m
 	}
 	hi.RoutableIPs = append(prefs.AdvertiseRoutes[:0:0], prefs.AdvertiseRoutes...)