Add a referer header to external requests

This fixes YouTube embeds

Author: GarboMuffin

src-main/index.js

@@ -87,6 +87,21 @@ app.on('session-created', (session) => {
     window.onBeforeRequest(details, callback);
   });
 
+  session.webRequest.onBeforeSendHeaders((details, callback) => {
+    const url = details.url.toLowerCase();
+    if (url.startsWith('devtools:')) {
+      return callback({});
+    }
+
+    const webContents = details.webContents;
+    const window = AbstractWindow.getWindowByWebContents(webContents);
+    if (!webContents || !window) {
+      return callback({});
+    }
+
+    window.onBeforeSendHeaders(details, callback);
+  });
+
   session.webRequest.onHeadersReceived((details, callback) => {
     const window = AbstractWindow.getWindowByWebContents(details.webContents);
     if (!window) {

src-main/windows/abstract.js

@@ -346,6 +346,15 @@ class AbstractWindow {
     callback({});
   }
 
+  /**
+   * @param {Electron.OnBeforeSendHeadersListenerDetails} details
+   * @param {(response: Electron.BeforeSendResponse) => void} callback 
+   */
+  onBeforeSendHeaders (details, callback) {
+    // to be overridden
+    callback({});
+  }
+
   /**
    * @param {Electron.OnHeadersReceivedListenerDetails} details
    * @param {(response: Electron.HeadersReceivedResponse) => void} callback

src-main/windows/project-running-window.js

@@ -131,6 +131,23 @@ class ProjectRunningWindow extends AbtractWindow {
     super.onBeforeRequest(details, callback);
   }
 
+  onBeforeSendHeaders (details, callback) {
+    const parsed = new URL(details.url);
+
+    if (WEB_PROTOCOLS.includes(parsed.protocol)) {
+      // Some third-party APIs (eg. YouTube embeds) require a non-empty referer header.
+      // The website being contacted already receives "turbowarp-desktop/x.y.z" in the user-agent so this isn't
+      // revealing any metadata that they couldn't already have access to.
+      return callback({
+        requestHeaders: {
+          'referer': 'https://docs.turbowarp.org/desktop/referer'
+        }
+      });
+    }
+
+    callback({});
+  }
+
   onHeadersReceived (details, callback) {
     if (
       settings.bypassCORS &&