diff --git a/src/lib/ContentMetaData.js b/src/lib/ContentMetaData.js
new file mode 100644
index 0000000..c60d75e
--- /dev/null
+++ b/src/lib/ContentMetaData.js
@@ -0,0 +1,30 @@
+class ContentMetaData {
+  constructor(request, defaultCharset = "utf-8") {
+    this.defaultCharset = defaultCharset;
+    let {responseHeaders} = request;
+    for (let h of responseHeaders) {
+      if (/^\s*Content-(Type|Disposition)\s*$/i.test(h.name)) {
+        this[h.name.split("-")[1].trim().toLowerCase()] = h.value;
+      }
+    }
+  }
+
+  get charset() {
+    let charset = this.defaultCharset;
+    if (this.type) {
+      let m = this.type.match(/;\s*charset\s*=\s*(\S+)/);
+      if (m) {
+        charset = m[1];
+      }
+    }
+    Object.defineProperty(this, "charset", { value: charset, writable: false, configurable: true })
+  }
+
+  createDecoder() {
+    try {
+      return new TextDecoder(charset);
+    } catch (e) {
+      return new TextDecoder(this.defaultCharset);
+    }
+  }
+};
diff --git a/src/lib/restricted.js b/src/lib/restricted.js
new file mode 100644
index 0000000..ae85ba8
--- /dev/null
+++ b/src/lib/restricted.js
@@ -0,0 +1,29 @@
+{
+  // see https://bugzilla.mozilla.org/show_bug.cgi?id=1415644
+  let domains = [
+  "accounts-static.cdn.mozilla.net",
+  "accounts.firefox.com",
+  "addons.cdn.mozilla.net",
+  "addons.mozilla.org",
+  "api.accounts.firefox.com",
+  "content.cdn.mozilla.net",
+  "content.cdn.mozilla.net",
+  "discovery.addons.mozilla.org",
+  "input.mozilla.org",
+  "install.mozilla.org",
+  "oauth.accounts.firefox.com",
+  "profile.accounts.firefox.com",
+  "support.mozilla.org",
+  "sync.services.mozilla.com",
+  "testpilot.firefox.com",
+  ];
+
+  function isRestrictedURL(u) {
+    try {
+      if (typeof u === "string") u = new URL(u);
+      return u.protocol === "https:" && domains.includes(u.hostname);
+    } catch (e) {
+      return false;
+    }
+  }
+}
diff --git a/src/manifest.json b/src/manifest.json
index d592361..3caf671 100644
--- a/src/manifest.json
+++ b/src/manifest.json
@@ -8,7 +8,7 @@
       "strict_min_version": "59.0"
     }
   },
-  "version": "10.1.8.3rc8",
+  "version": "10.1.8.3rc9",
   "description": "__MSG_Description__",
 
   "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'none'",
@@ -39,6 +39,7 @@
       "lib/include.js",
       "lib/punycode.js",
       "lib/tld.js",
+      "lib/ContentMetaData.js",
       "common/Policy.js",
       "common/locale.js",
       "common/Entities.js",