android: modify mullvad exit node detection logic (#656)

updates tailscale/corp#29045

We ran into an issue where the current detection logic was not
sufficient to filter out mullvad nodes.  This modifies the logic so we
scan both the Name and ComputedName for the mullvad domain and
also treat all nodes with location info as mullvad nodes.  While all
of these conditions *should* be true for any mullvad node, in practice
it's possible that they aren't so we or them together for some redundancy
and define a mullvad exit node to be any node where any of these
conditions is true.

Signed-off-by: Jonathan Nobels <[email protected]>

Author: barnstar

android/src/main/java/com/tailscale/ipn/ui/model/TailCfg.kt

@@ -15,9 +15,9 @@ import com.tailscale.ipn.ui.util.DisplayAddress
 import com.tailscale.ipn.ui.util.TimeUtil
 import com.tailscale.ipn.ui.util.flag
 import com.tailscale.ipn.ui.viewModel.PeerSettingInfo
-import java.util.Date
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.JsonElement
+import java.util.Date
 
 class Tailcfg {
   @Serializable
@@ -107,8 +107,13 @@ class Tailcfg {
     val isExitNode: Boolean =
         (AllowedIPs?.contains("0.0.0.0/0") ?: false) && (AllowedIPs?.contains("::/0") ?: false)
 
+    // mullvad nodes are exit nodes with a mullvad.ts.net domain *or* Location Info.
+    // These checks are intentionally redundant to avoid false negatives.
     val isMullvadNode: Boolean
-      get() = Name.endsWith(".mullvad.ts.net.")
+      get() =
+          Name.endsWith(".mullvad.ts.net") ||
+              ComputedName?.endsWith(".mullvad.ts.net") == true ||
+              Hostinfo.Location != null
 
     val displayName: String
       get() = ComputedName ?: Name