1 files changed, 48 insertions, 0 deletions
diff --git a/toolkit/actors/AboutHttpsOnlyErrorParent.sys.mjs b/toolkit/actors/AboutHttpsOnlyErrorParent.sys.mjs
new file mode 100644
index 0000000000..a7a4b23cfa
--- /dev/null
+++ b/toolkit/actors/AboutHttpsOnlyErrorParent.sys.mjs
@@ -0,0 +1,48 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const { HomePage } = ChromeUtils.import("resource:///modules/HomePage.jsm");
+import { PrivateBrowsingUtils } from "resource://gre/modules/PrivateBrowsingUtils.sys.mjs";
+
+export class AboutHttpsOnlyErrorParent extends JSWindowActorParent {
+  get browser() {
+    return this.browsingContext.top.embedderElement;
+  }
+
+  receiveMessage(aMessage) {
+    switch (aMessage.name) {
+      case "goBack":
+        this.goBackFromErrorPage(this.browser);
+        break;
+    }
+  }
+
+  goBackFromErrorPage(aBrowser) {
+    if (!aBrowser.canGoBack) {
+      // If the unsafe page is the first or the only one in history, go to the
+      // start page.
+      aBrowser.fixupAndLoadURIString(
+        this.getDefaultHomePage(aBrowser.ownerGlobal),
+        {
+          triggeringPrincipal:
+            Services.scriptSecurityManager.getSystemPrincipal(),
+        }
+      );
+    } else {
+      aBrowser.goBack();
+    }
+  }
+
+  getDefaultHomePage(win) {
+    if (PrivateBrowsingUtils.isWindowPrivate(win)) {
+      return win.BROWSER_NEW_TAB_URL || "about:blank";
+    }
+    let url = HomePage.getDefault();
+    // If url is a pipe-delimited set of pages, just take the first one.
+    if (url.includes("|")) {
+      url = url.split("|")[0];
+    }
+    return url;
+  }
+}