From 4d2986ea595d7bd29c1253c33d2171bbd7665ece Mon Sep 17 00:00:00 2001
From: attila <attila@juce.com>
Date: Wed, 22 May 2024 15:28:29 +0200
Subject: [PATCH] Add new WebBrowserComponent option for file access control on
 Apple platforms

If allowAccessToEnclosingDirectory is set to true, it is now possible
for the WkWebView implementation to access sibling files relative to a
file specified with the file:// scheme.

This allows an iOS app to load an HTML file in the documents directory,
and that HTML file can reference and load image files inside the HTML
file's parent directory.
---
 .../misc/juce_WebBrowserComponent.h           | 32 +++++++++++++++++++
 .../native/juce_WebBrowserComponent_mac.mm    | 24 ++++++++++++--
 2 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/modules/juce_gui_extra/misc/juce_WebBrowserComponent.h b/modules/juce_gui_extra/misc/juce_WebBrowserComponent.h
index 7f5b836ff1..2d9b18b437 100644
--- a/modules/juce_gui_extra/misc/juce_WebBrowserComponent.h
+++ b/modules/juce_gui_extra/misc/juce_WebBrowserComponent.h
@@ -212,6 +212,29 @@ public:
             Colour backgroundColour;
         };
 
+        /** Options specific to the WkWebView backend used on Apple systems. These options will be
+            ignored on non-Apple platforms.
+        */
+        class AppleWkWebView
+        {
+        public:
+            /** Specifies whether the WebView is allowed to access siblings of files specified with
+                the file:// URL scheme.
+
+                Allowing this is a potential security vulnerability if you don't have full control
+                over the file that you are opening.
+            */
+            [[nodiscard]] AppleWkWebView withAllowAccessToEnclosingDirectory (bool x) const
+            {
+                return withMember (*this, &AppleWkWebView::allowAccessToEnclosingDirectory, x);
+            }
+
+            auto getAllowAccessToEnclosingDirectory() const { return allowAccessToEnclosingDirectory; }
+
+        private:
+            bool allowAccessToEnclosingDirectory = false;
+        };
+
         /** Specifies options that apply to the Windows implementation when the WebView2 feature is
             enabled.
 
@@ -222,6 +245,13 @@ public:
             return withMember (*this, &Options::winWebView2, winWebView2Options);
         }
 
+        /** Specifies options that influence the WebBrowserComponent's behaviour on Apple systems.
+        */
+        [[nodiscard]] Options withAppleWkWebViewOptions (const AppleWkWebView& appleWkWebViewOptions) const
+        {
+            return withMember (*this, &Options::appleWkWebView, appleWkWebViewOptions);
+        }
+
         /** Enables native integration features for the code running inside the WebBrowserComponent.
 
             This injects data and function objects under `window.__JUCE__.backend` through which
@@ -342,6 +372,7 @@ public:
         auto        keepsPageLoadedWhenBrowserIsHidden() const noexcept  { return keepPageLoadedWhenBrowserIsHidden; }
         auto        getUserAgent() const                                 { return userAgent; }
         auto        getWinWebView2BackendOptions() const                 { return winWebView2; }
+        auto        getAppleWkWebViewOptions() const                     { return appleWkWebView; }
         auto        getNativeIntegrationsEnabled() const                 { return enableNativeIntegration; }
         const auto& getNativeFunctions() const                           { return nativeFunctions; }
         const auto& getEventListeners() const                            { return eventListeners; }
@@ -357,6 +388,7 @@ public:
         bool enableNativeIntegration = false;
         String userAgent;
         WinWebView2 winWebView2;
+        AppleWkWebView appleWkWebView;
         std::map<Identifier, NativeFunction> nativeFunctions;
         std::vector<std::pair<Identifier, NativeEventListener>> eventListeners;
         StringArray userScripts;
diff --git a/modules/juce_gui_extra/native/juce_WebBrowserComponent_mac.mm b/modules/juce_gui_extra/native/juce_WebBrowserComponent_mac.mm
index 7c4cad144b..c91417a683 100644
--- a/modules/juce_gui_extra/native/juce_WebBrowserComponent_mac.mm
+++ b/modules/juce_gui_extra/native/juce_WebBrowserComponent_mac.mm
@@ -818,7 +818,9 @@ public:
           delegateConnector (implIn.owner,
                              [this] (const auto& m) { owner.handleNativeEvent (m); },
                              [this] (const auto& r) { return owner.handleResourceRequest (r); },
-                             browserOptions)
+                             browserOptions),
+          allowAccessToEnclosingDirectory (browserOptions.getAppleWkWebViewOptions()
+                                                         .getAllowAccessToEnclosingDirectory())
     {
         ObjCObjectHandle<WKWebViewConfiguration*> config { [WKWebViewConfiguration new] };
         id preferences = [config.get() preferences];
@@ -987,8 +989,23 @@ public:
         {
             auto file = URL (url).getLocalFile();
 
-            if (NSURL* nsUrl = [NSURL fileURLWithPath: juceStringToNS (file.getFullPathName())])
-                [webView.get() loadFileURL: appendParametersToFileURL (url, nsUrl) allowingReadAccessToURL: nsUrl];
+            NSURL* nsUrl = [NSURL fileURLWithPath: juceStringToNS (file.getFullPathName())];
+
+            auto* accessPath = [&]
+            {
+                if (! allowAccessToEnclosingDirectory)
+                    return nsUrl;
+
+                auto* parentUrl = [NSURL fileURLWithPath: juceStringToNS (file.getParentDirectory().getFullPathName())];
+
+                if (parentUrl == nullptr)
+                    return nsUrl;
+
+                return parentUrl;
+            }();
+
+            if (nsUrl != nullptr)
+                [webView.get() loadFileURL: appendParametersToFileURL (url, nsUrl) allowingReadAccessToURL: accessPath];
         }
         else if (NSMutableURLRequest* request = getRequestForURL (url, headers, postData))
         {
@@ -1061,6 +1078,7 @@ public:
 private:
     WebBrowserComponent::Impl& owner;
     DelegateConnector delegateConnector;
+    bool allowAccessToEnclosingDirectory = false;
     LastFocusChange lastFocusChange;
     ObjCObjectHandle<WKWebView*> webView;
     ObjCObjectHandle<id> webViewDelegate;