From 33cdc14070b4c3217b816f22cb74cc0f88168ea0 Mon Sep 17 00:00:00 2001
From: Jeroen Leenarts <jeroen.leenarts@gmail.com>
Date: Mon, 1 Oct 2018 15:37:15 +0200
Subject: [PATCH] Don't crash on failure to obtain version info and inform user
 on what is needed to be able to retrieve version info from the Go client.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 ...+SettingsTableViewControllerDelegate.swift | 24 ++++++++++++-------
 .../SetttingsTableViewController.swift        | 18 ++++++++++++--
 .../PacketTunnelProvider.swift                |  4 +++-
 3 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/WireGuard/Coordinators/AppCoordinator+SettingsTableViewControllerDelegate.swift b/WireGuard/Coordinators/AppCoordinator+SettingsTableViewControllerDelegate.swift
index 5784f5d..d19422c 100644
--- a/WireGuard/Coordinators/AppCoordinator+SettingsTableViewControllerDelegate.swift
+++ b/WireGuard/Coordinators/AppCoordinator+SettingsTableViewControllerDelegate.swift
@@ -7,22 +7,28 @@ import PromiseKit
 import NetworkExtension
 
 enum GoVersionCoordinatorError: Error {
-    case noSession
+    case noEnabledSession
+    case noResponse
 }
 
 extension AppCoordinator: SettingsTableViewControllerDelegate {
     func goVersionInformation() -> Promise<String> {
         return Promise(resolver: { (resolver) in
-            guard let session = self.providerManagers?.first?.connection as? NETunnelProviderSession else {
-                resolver.reject(GoVersionCoordinatorError.noSession)
+            guard let session = self.providerManagers?.first(where: { $0.isEnabled })?.connection as? NETunnelProviderSession else {
+                resolver.reject(GoVersionCoordinatorError.noEnabledSession)
                 return
             }
-            try session.sendProviderMessage(ExtensionMessage.requestVersion.data, responseHandler: { (data) in
-                guard let responseString = String(data: data!, encoding: .utf8) else {
-                    return
-                }
-                resolver.fulfill(responseString)
-            })
+            do {
+                try session.sendProviderMessage(ExtensionMessage.requestVersion.data, responseHandler: { (data) in
+                    guard let data = data, let responseString = String(data: data, encoding: .utf8) else {
+                        resolver.reject(GoVersionCoordinatorError.noResponse)
+                        return
+                    }
+                    resolver.fulfill(responseString)
+                })
+            } catch {
+                resolver.reject(error)
+            }
         })
     }
 
diff --git a/WireGuard/ViewControllers/SetttingsTableViewController.swift b/WireGuard/ViewControllers/SetttingsTableViewController.swift
index 0421815..8f87bb7 100644
--- a/WireGuard/ViewControllers/SetttingsTableViewController.swift
+++ b/WireGuard/ViewControllers/SetttingsTableViewController.swift
@@ -35,8 +35,15 @@ class SettingsTableViewController: UITableViewController {
                 label.text = goVersion
             }
             return Guarantee.value(())
-            }.recover({ (_) in
-                self.goVersionInfoLabel.text = NSLocalizedString("Unknown", comment: "")
+            }.recover({ (error) in
+                switch error {
+                case GoVersionCoordinatorError.noEnabledSession:
+                    self.goVersionInfoLabel.text = NSLocalizedString("Unavailable", comment: "")
+                    self.showNotEnabledAlert()
+                default:
+                    self.goVersionInfoLabel.text = NSLocalizedString("Unknown", comment: "")
+                }
+
             })
     }
 
@@ -69,6 +76,13 @@ class SettingsTableViewController: UITableViewController {
         return self.delegate?.goVersionInformation() ?? Promise(error: GoVersionError.noDelegate)
     }
 
+    private func showNotEnabledAlert() {
+        let notEnabledAlertController = UIAlertController(title: NSLocalizedString("Go version", comment: ""), message: NSLocalizedString("Enable a WireGuard config by connecting or by selecting one in the VPN section of the device Settings app.", comment: ""), preferredStyle: .alert)
+        notEnabledAlertController.addAction(UIAlertAction(title: NSLocalizedString("Ok", comment: "Generic OK button"), style: .default, handler: nil))
+
+        present(notEnabledAlertController, animated: true, completion: nil)
+    }
+
     private func showCopyConfirmation() {
         let confirmationAlertController = UIAlertController(title: NSLocalizedString("Copied version information", comment: ""), message: UIPasteboard.general.string, preferredStyle: .alert)
         confirmationAlertController.addAction(UIAlertAction(title: NSLocalizedString("Ok", comment: "Generic OK button"), style: .default, handler: nil))
diff --git a/WireGuardNetworkExtension/PacketTunnelProvider.swift b/WireGuardNetworkExtension/PacketTunnelProvider.swift
index e0536b2..103dc90 100644
--- a/WireGuardNetworkExtension/PacketTunnelProvider.swift
+++ b/WireGuardNetworkExtension/PacketTunnelProvider.swift
@@ -112,7 +112,9 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
     override func handleAppMessage(_ messageData: Data, completionHandler: ((Data?) -> Void)?) {
         let responseData: Data?
 
-        switch ExtensionMessage(messageData) {
+        let message = ExtensionMessage(messageData)
+
+        switch message {
         case ExtensionMessage.requestVersion:
             responseData = (wgVersion().flatMap { String(cString: $0) } ?? "").data(using: .utf8)
         default: