VoIP: Fallback to matrix.org STUN server with a confirmation dialog

#2646

CHANGES.rst

@@ -7,6 +7,7 @@ Improvements:
  * Privacy: Make clear that device names are publicly readable (#2662).
  * Widgets: Whitelist [MSC1961](https://github.com/matrix-org/matrix-doc/pull/1961) widget urls.
  * Settings: CALLS section: Always display the CallKit option but grey it out when not available (only on China).
+ * VoIP: Fallback to matrix.org STUN server with a confirmation dialog (#2646).
 
 Changes in 0.9.2 (2019-08-08)
 ===============================================

Riot/AppDelegate.m

@@ -2605,6 +2605,11 @@ - (void)initMatrixSessions
                 // Let's call invite be valid for 1 minute
                 mxSession.callManager.inviteLifetime = 60000;
 
+                if (RiotSettings.shared.allowStunServerFallback)
+                {
+                    mxSession.callManager.fallbackSTUNServer = RiotSettings.shared.stunServerFallback;
+                }
+
                 // Setup CallKit
                 if ([MXCallKitAdapter callKitAvailable])
                 {
@@ -3850,6 +3855,12 @@ - (void)dismissCallViewController:(MXKCallViewController *)callViewController co
                     NSString *btnTitle = [NSString stringWithFormat:NSLocalizedStringFromTable(@"active_call_details", @"Vector", nil), callViewController.callerNameLabel.text];
                     [self addCallStatusBar:btnTitle];
                 }
+
+                if ([callViewController isKindOfClass:[CallViewController class]]
+                    && ((CallViewController*)callViewController).shouldPromptForStunServerFallback)
+                {
+                    [self promptForStunServerFallback];
+                }
 
                 if (completion)
                 {
@@ -3883,6 +3894,52 @@ - (void)dismissCallViewController:(MXKCallViewController *)callViewController co
     }
 }
 
+- (void)promptForStunServerFallback
+{
+    [_errorNotification dismissViewControllerAnimated:NO completion:nil];
+
+    NSString *stunFallbackHost = RiotSettings.shared.stunServerFallback;
+    // Remove "stun:"
+    stunFallbackHost = [stunFallbackHost componentsSeparatedByString:@":"].lastObject;
+
+    MXSession *mainSession = self.mxSessions.firstObject;
+    NSString *homeServerName = mainSession.matrixRestClient.credentials.homeServerName;
+
+    NSString *message = [NSString stringWithFormat:@"%@\n\n%@",
+                         [NSString stringWithFormat:NSLocalizedStringFromTable(@"call_no_stun_server_error_message_1", @"Vector", nil), homeServerName],
+                         [NSString stringWithFormat: NSLocalizedStringFromTable(@"call_no_stun_server_error_message_2", @"Vector", nil), stunFallbackHost]];
+
+    _errorNotification = [UIAlertController alertControllerWithTitle:NSLocalizedStringFromTable(@"call_no_stun_server_error_title", @"Vector", nil)
+                                                             message:message
+                                                      preferredStyle:UIAlertControllerStyleAlert];
+
+    [_errorNotification addAction:[UIAlertAction actionWithTitle:[NSString stringWithFormat: NSLocalizedStringFromTable(@"call_no_stun_server_error_use_fallback_button", @"Vector", nil), stunFallbackHost]
+                                                           style:UIAlertActionStyleDefault
+                                                         handler:^(UIAlertAction * action) {
+
+                                                             RiotSettings.shared.allowStunServerFallback = YES;
+                                                             mainSession.callManager.fallbackSTUNServer = RiotSettings.shared.stunServerFallback;
+
+                                                             [AppDelegate theDelegate].errorNotification = nil;
+                                                         }]];
+
+    [_errorNotification addAction:[UIAlertAction actionWithTitle:[NSBundle mxk_localizedStringForKey:@"cancel"]
+                                                           style:UIAlertActionStyleCancel
+                                                         handler:^(UIAlertAction * action) {
+
+                                                             RiotSettings.shared.allowStunServerFallback = NO;
+
+                                                             [AppDelegate theDelegate].errorNotification = nil;
+                                                         }]];
+
+    // Display the error notification
+    if (!isErrorNotificationSuspended)
+    {
+        [_errorNotification mxk_setAccessibilityIdentifier:@"AppDelegateErrorAlert"];
+        [self showNotificationAlert:_errorNotification];
+    }
+}
+
 #pragma mark - Jitsi call
 
 - (void)displayJitsiViewControllerWithWidget:(Widget*)jitsiWidget andVideo:(BOOL)video

Riot/Assets/Riot-Defaults.plist

@@ -59,6 +59,8 @@
 	<false/>
 	<key>createConferenceCallsWithJitsi</key>
 	<true/>
+	<key>stunServerFallback</key>
+	<string>stun:turn.matrix.org</string>
 	<key>enableRageShake</key>
 	<true/>
 	<key>maxAllowedMediaCacheSize</key>

Riot/Assets/en.lproj/Vector.strings

@@ -405,6 +405,9 @@
 
 "settings_enable_callkit" = "Integrated calling";
 "settings_callkit_info" = "Receive incoming calls on your lock screen. See your Riot calls in the system's call history. If iCloud is enabled, this call history will be shared with Apple.";
+"settings_calls_stun_server_fallback_button" = "Allow fallback call assist server";
+"settings_calls_stun_server_fallback_description" = "Allow fallback call assist server %@ when your homeserver does not offer one (your IP address would be shared during a call).";
+
 "settings_ui_language" = "Language";
 "settings_ui_theme" = "Theme";
 "settings_ui_theme_auto" = "Auto";
@@ -631,6 +634,11 @@
 "call_already_displayed" = "There is already a call in progress.";
 "call_jitsi_error" = "Failed to join the conference call.";
 
+"call_no_stun_server_error_title" ="Call failed due to misconfigured server";
+"call_no_stun_server_error_message_1" ="Please ask the administrator of your homeserver %@ to configure a TURN server in order for calls to work reliably.";
+"call_no_stun_server_error_message_2" ="Alternatively, you can try to use the public server at %@, but this will not be as reliable, and it will share your IP address with that server. You can also manage this in Settings";
+"call_no_stun_server_error_use_fallback_button" = "Try using %@";
+
 // No VoIP support
 "no_voip_title" = "Incoming call";
 "no_voip" = "%@ is calling you but %@ does not support calls yet.\nYou can ignore this notification and answer the call from another device or you can reject it.";

Riot/Generated/RiotDefaults.swift

@@ -39,6 +39,7 @@ internal enum RiotDefaults {
   internal static let showRedactionsInRoomHistory: Bool = _document["showRedactionsInRoomHistory"]
   internal static let showUnsupportedEventsInRoomHistory: Bool = _document["showUnsupportedEventsInRoomHistory"]
   internal static let sortRoomMembersUsingLastSeenTime: Bool = _document["sortRoomMembersUsingLastSeenTime"]
+  internal static let stunServerFallback: String = _document["stunServerFallback"]
   internal static let syncLocalContacts: Bool = _document["syncLocalContacts"]
   internal static let webAppUrl: String = _document["webAppUrl"]
   internal static let webAppUrlBeta: String = _document["webAppUrlBeta"]

Riot/Generated/Strings.swift

@@ -370,6 +370,22 @@ internal enum VectorL10n {
   internal static var callJitsiError: String { 
     return VectorL10n.tr("Vector", "call_jitsi_error") 
   }
+  /// Please ask the administrator of your homeserver %@ to configure a TURN server in order for calls to work reliably.
+  internal static func callNoStunServerErrorMessage1(_ p1: String) -> String {
+    return VectorL10n.tr("Vector", "call_no_stun_server_error_message_1", p1)
+  }
+  /// Alternatively, you can try to use the public server at %@, but this will not be as reliable, and it will share your IP address with that server. You can also manage this in Settings
+  internal static func callNoStunServerErrorMessage2(_ p1: String) -> String {
+    return VectorL10n.tr("Vector", "call_no_stun_server_error_message_2", p1)
+  }
+  /// Call failed due to misconfigured server
+  internal static var callNoStunServerErrorTitle: String { 
+    return VectorL10n.tr("Vector", "call_no_stun_server_error_title") 
+  }
+  /// Try using %@
+  internal static func callNoStunServerErrorUseFallbackButton(_ p1: String) -> String {
+    return VectorL10n.tr("Vector", "call_no_stun_server_error_use_fallback_button", p1)
+  }
   /// Camera
   internal static var camera: String { 
     return VectorL10n.tr("Vector", "camera") 
@@ -2394,6 +2410,14 @@ internal enum VectorL10n {
   internal static var settingsCallsSettings: String { 
     return VectorL10n.tr("Vector", "settings_calls_settings") 
   }
+  /// Allow fallback call assist server
+  internal static var settingsCallsStunServerFallbackButton: String { 
+    return VectorL10n.tr("Vector", "settings_calls_stun_server_fallback_button") 
+  }
+  /// Allow fallback call assist server %@ when your homeserver does not offer one (your IP address would be shared during a call).
+  internal static func settingsCallsStunServerFallbackDescription(_ p1: String) -> String {
+    return VectorL10n.tr("Vector", "settings_calls_stun_server_fallback_description", p1)
+  }
   /// Change password
   internal static var settingsChangePassword: String { 
     return VectorL10n.tr("Vector", "settings_change_password") 

Riot/Managers/Settings/RiotSettings.swift

@@ -30,6 +30,8 @@ final class RiotSettings: NSObject {
         static let notificationsShowDecryptedContent = "showDecryptedContent"
         static let pinRoomsWithMissedNotifications = "pinRoomsWithMissedNotif"
         static let pinRoomsWithUnreadMessages = "pinRoomsWithUnread"
+        static let allowStunServerFallback = "allowStunServerFallback"
+        static let stunServerFallback = "stunServerFallback"
     }
 
     /// Riot Standard Room Member Power Level
@@ -119,4 +121,24 @@ final class RiotSettings: NSObject {
             UserDefaults.standard.set(newValue, forKey: UserDefaultsKeys.createConferenceCallsWithJitsi)
         }
     }
+
+
+    // MARK: Calls
+
+    /// Indicate if `allowStunServerFallback` settings has been set once.
+    var isAllowStunServerFallbackHasBeenSetOnce: Bool {
+        return UserDefaults.standard.object(forKey: UserDefaultsKeys.allowStunServerFallback) != nil
+    }
+
+    var allowStunServerFallback: Bool {
+        get {
+            return UserDefaults.standard.bool(forKey: UserDefaultsKeys.allowStunServerFallback)
+        } set {
+            UserDefaults.standard.set(newValue, forKey: UserDefaultsKeys.allowStunServerFallback)
+        }
+    }
+
+    var stunServerFallback: String? {
+        return UserDefaults.standard.string(forKey: UserDefaultsKeys.stunServerFallback)
+    }
 }

Riot/Modules/Call/CallViewController.h

@@ -26,4 +26,7 @@
 
 @property (unsafe_unretained, nonatomic) IBOutlet NSLayoutConstraint *callerImageViewWidthConstraint;
 
+// At the end of call, this flag indicates if the prompt to use the fallback should be displayed
+@property (nonatomic) BOOL shouldPromptForStunServerFallback;
+
 @end

Riot/Modules/Call/CallViewController.m

@@ -39,6 +39,9 @@ @interface CallViewController ()
 
     // Observe kThemeServiceDidChangeThemeNotification to handle user interface theme change.
     id kThemeServiceDidChangeThemeNotificationObserver;
+
+    // Flag to compute self.shouldPromptForStunServerFallback
+    BOOL promptForStunServerFallback;
 }
 
 @end
@@ -52,6 +55,9 @@ - (void)finalizeInit
     // Setup `MXKViewControllerHandling` properties
     self.enableBarTintColorStatusChange = NO;
     self.rageShakeManager = [RageShakeManager sharedManager];
+
+    promptForStunServerFallback = NO;
+    _shouldPromptForStunServerFallback = NO;
 }
 
 - (void)viewDidLoad
@@ -229,6 +235,13 @@ - (UIView *)createIncomingCallView
 
 #pragma mark - MXCallDelegate
 
+- (void)call:(MXCall *)call stateDidChange:(MXCallState)state reason:(MXEvent *)event
+{
+    [super call:call stateDidChange:state reason:event];
+
+    [self checkStunServerFallbackWithCallState:state];
+}
+
 - (void)call:(MXCall *)call didEncounterError:(NSError *)error
 {
     if ([error.domain isEqualToString:MXEncryptingErrorDomain]
@@ -333,6 +346,42 @@ - (void)call:(MXCall *)call didEncounterError:(NSError *)error
     }
 }
 
+
+#pragma mark - Fallback STUN server
+
+- (void)checkStunServerFallbackWithCallState:(MXCallState)callState
+{
+    // Detect if we should display the prompt to fallback to the STUN server defined
+    // in the app plist if the homeserver does not provide STUN or TURN servers.
+    // We should if the call ends while we were in connecting state
+    if (!self.mainSession.callManager.turnServers
+        && !self.mainSession.callManager.fallbackSTUNServer
+        && !RiotSettings.shared.isAllowStunServerFallbackHasBeenSetOnce)
+    {
+        switch (callState)
+        {
+            case MXCallStateConnecting:
+                promptForStunServerFallback = YES;
+                break;
+
+            case MXCallStateConnected:
+                promptForStunServerFallback = NO;
+                break;
+
+            case MXCallStateEnded:
+                if (promptForStunServerFallback)
+                {
+                    _shouldPromptForStunServerFallback = YES;
+                    //NSLog(@"####### :)");
+                }
+
+            default:
+                break;
+        }
+    }
+}
+
+
 #pragma mark - Properties
 
 - (UIImage*)picturePlaceholder

Riot/Modules/Settings/SettingsViewController.m

@@ -86,7 +86,9 @@
 enum
 {
     CALLS_ENABLE_CALLKIT_INDEX = 0,
-    CALLS_DESCRIPTION_INDEX,
+    CALLS_CALLKIT_DESCRIPTION_INDEX,
+    CALLS_ENABLE_STUN_SERVER_FALLBACK_INDEX,
+    CALLS_STUN_SERVER_FALLBACK_DESCRIPTION_INDEX,
     CALLS_COUNT
 };
 
@@ -1266,6 +1268,11 @@ - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger
     else if (section == SETTINGS_SECTION_CALLS_INDEX)
     {
         count = CALLS_COUNT;
+
+        if (!RiotSettings.shared.stunServerFallback)
+        {
+            count -= 2;
+        }
     }
     else if (section == SETTINGS_SECTION_USER_INTERFACE_INDEX)
     {
@@ -1834,7 +1841,7 @@ - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(N
 
             cell = labelAndSwitchCell;
         }
-        else if (row == CALLS_DESCRIPTION_INDEX)
+        else if (row == CALLS_CALLKIT_DESCRIPTION_INDEX)
         {
             MXKTableViewCell *globalInfoCell = [self getDefaultTableViewCell:tableView];
             globalInfoCell.textLabel.text = NSLocalizedStringFromTable(@"settings_callkit_info", @"Vector", nil);
@@ -1846,6 +1853,30 @@ - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(N
                 globalInfoCell.textLabel.enabled = NO;
             }
 
+            cell = globalInfoCell;
+        }
+        else if (row == CALLS_ENABLE_STUN_SERVER_FALLBACK_INDEX)
+        {
+            MXKTableViewCellWithLabelAndSwitch* labelAndSwitchCell = [self getLabelAndSwitchCell:tableView forIndexPath:indexPath];
+            labelAndSwitchCell.mxkLabel.text = NSLocalizedStringFromTable(@"settings_calls_stun_server_fallback_button", @"Vector", nil);
+            labelAndSwitchCell.mxkSwitch.on = RiotSettings.shared.allowStunServerFallback;
+            labelAndSwitchCell.mxkSwitch.onTintColor = ThemeService.shared.theme.tintColor;
+            labelAndSwitchCell.mxkSwitch.enabled = YES;
+            [labelAndSwitchCell.mxkSwitch addTarget:self action:@selector(toggleStunServerFallback:) forControlEvents:UIControlEventTouchUpInside];
+
+            cell = labelAndSwitchCell;
+        }
+        else if (row == CALLS_STUN_SERVER_FALLBACK_DESCRIPTION_INDEX)
+        {
+            NSString *stunFallbackHost = RiotSettings.shared.stunServerFallback;
+            // Remove "stun:"
+            stunFallbackHost = [stunFallbackHost componentsSeparatedByString:@":"].lastObject;
+
+            MXKTableViewCell *globalInfoCell = [self getDefaultTableViewCell:tableView];
+            globalInfoCell.textLabel.text = [NSString stringWithFormat:NSLocalizedStringFromTable(@"settings_calls_stun_server_fallback_description", @"Vector", nil), stunFallbackHost];
+            globalInfoCell.textLabel.numberOfLines = 0;
+            globalInfoCell.selectionStyle = UITableViewCellSelectionStyleNone;
+
             cell = globalInfoCell;
         }
     }
@@ -2945,6 +2976,14 @@ - (void)toggleCallKit:(id)sender
     [MXKAppSettings standardAppSettings].enableCallKit = switchButton.isOn;
 }
 
+- (void)toggleStunServerFallback:(id)sender
+{
+    UISwitch *switchButton = (UISwitch*)sender;
+    RiotSettings.shared.allowStunServerFallback = switchButton.isOn;
+
+    self.mainSession.callManager.fallbackSTUNServer = RiotSettings.shared.allowStunServerFallback ? RiotSettings.shared.stunServerFallback : nil;
+}
+
 - (void)toggleShowDecodedContent:(id)sender
 {
     UISwitch *switchButton = (UISwitch*)sender;