NE: Handle bad domain names and Activate On Demand

This combination causes iOS to keep trying to bring up the tunnel,
leading to a lot of displayMessage() alerts.

In this fix, if we get a DNS resolution error in an Activate On Demand
enabled tunnel, we silently retry 9 times (with a 4-second delay before
each retry) and then show the displayMessage() alert.

Signed-off-by: Roopesh Chander <roop@roopc.net>

WireGuard/Shared/NETunnelProviderProtocol+Extension.swift

@@ -4,7 +4,7 @@
 import NetworkExtension
 
 extension NETunnelProviderProtocol {
-    convenience init?(tunnelConfiguration: TunnelConfiguration) {
+    convenience init?(tunnelConfiguration: TunnelConfiguration, isActivateOnDemandEnabled: Bool) {
         assert(!tunnelConfiguration.interface.name.isEmpty)
         guard let serializedTunnelConfiguration = try? JSONEncoder().encode(tunnelConfiguration) else { return nil }
 
@@ -14,7 +14,8 @@ extension NETunnelProviderProtocol {
         providerBundleIdentifier = "\(appId).network-extension"
         providerConfiguration = [
             "tunnelConfiguration": serializedTunnelConfiguration,
-            "tunnelConfigurationVersion": 1
+            "tunnelConfigurationVersion": 1,
+            "isActivateOnDemandEnabled": isActivateOnDemandEnabled
         ]
 
         let endpoints = tunnelConfiguration.peers.compactMap {$0.endpoint}
@@ -32,4 +33,8 @@ extension NETunnelProviderProtocol {
         guard let serializedTunnelConfiguration = providerConfiguration?["tunnelConfiguration"] as? Data else { return nil }
         return try? JSONDecoder().decode(TunnelConfiguration.self, from: serializedTunnelConfiguration)
     }
+
+    var isActivateOnDemandEnabled: Bool {
+        return (providerConfiguration?["isActivateOnDemandEnabled"] as? Bool) ?? false
+    }
 }