Move logic to extension: NETunnelProviderProtocol extension code should be shared

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

WireGuard/Shared/NETunnelProviderProtocol+Extension.swift

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: MIT
+// Copyright © 2018 WireGuard LLC. All Rights Reserved.
+
+import NetworkExtension
+
+extension NETunnelProviderProtocol {
+    convenience init?(tunnelConfiguration: TunnelConfiguration) {
+        assert(!tunnelConfiguration.interface.name.isEmpty)
+        guard let serializedTunnelConfiguration = try? JSONEncoder().encode(tunnelConfiguration) else { return nil }
+
+        self.init()
+
+        let appId = Bundle.main.bundleIdentifier!
+        providerBundleIdentifier = "\(appId).network-extension"
+        providerConfiguration = [
+            "tunnelConfiguration": serializedTunnelConfiguration,
+            "tunnelConfigurationVersion": 1
+        ]
+
+        let endpoints = tunnelConfiguration.peers.compactMap({$0.endpoint})
+        if endpoints.count == 1 {
+            serverAddress = endpoints.first!.stringRepresentation()
+        } else if endpoints.isEmpty {
+            serverAddress = "Unspecified"
+        } else {
+            serverAddress = "Multiple endpoints"
+        }
+        username = tunnelConfiguration.interface.name
+    }
+
+    func tunnelConfiguration() -> TunnelConfiguration? {
+        guard let serializedTunnelConfiguration = providerConfiguration?["tunnelConfiguration"] as? Data else { return nil }
+        return try? JSONDecoder().decode(TunnelConfiguration.self, from: serializedTunnelConfiguration)
+    }
+}