1 files changed, 132 insertions, 0 deletions
diff --git a/toolkit/actors/WebChannelChild.sys.mjs b/toolkit/actors/WebChannelChild.sys.mjs
new file mode 100644
index 0000000000..563f2566a0
--- /dev/null
+++ b/toolkit/actors/WebChannelChild.sys.mjs
@@ -0,0 +1,132 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* 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/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+import { ContentDOMReference } from "resource://gre/modules/ContentDOMReference.sys.mjs";
+
+// Preference containing the list (space separated) of origins that are
+// allowed to send non-string values through a WebChannel, mainly for
+// backwards compatability. See bug 1238128 for more information.
+const URL_WHITELIST_PREF = "webchannel.allowObject.urlWhitelist";
+
+let _cachedWhitelist = null;
+
+const CACHED_PREFS = {};
+XPCOMUtils.defineLazyPreferenceGetter(
+  CACHED_PREFS,
+  "URL_WHITELIST",
+  URL_WHITELIST_PREF,
+  "",
+  // Null this out so we update it.
+  () => (_cachedWhitelist = null)
+);
+
+export class WebChannelChild extends JSWindowActorChild {
+  handleEvent(event) {
+    if (event.type === "WebChannelMessageToChrome") {
+      return this._onMessageToChrome(event);
+    }
+    return undefined;
+  }
+
+  receiveMessage(msg) {
+    if (msg.name === "WebChannelMessageToContent") {
+      return this._onMessageToContent(msg);
+    }
+    return undefined;
+  }
+
+  _getWhitelistedPrincipals() {
+    if (!_cachedWhitelist) {
+      let urls = CACHED_PREFS.URL_WHITELIST.split(/\s+/);
+      _cachedWhitelist = urls.map(origin =>
+        Services.scriptSecurityManager.createContentPrincipalFromOrigin(origin)
+      );
+    }
+    return _cachedWhitelist;
+  }
+
+  _onMessageToChrome(e) {
+    // If target is window then we want the document principal, otherwise fallback to target itself.
+    let principal = e.target.nodePrincipal
+      ? e.target.nodePrincipal
+      : e.target.document.nodePrincipal;
+
+    if (e.detail) {
+      if (typeof e.detail != "string") {
+        // Check if the principal is one of the ones that's allowed to send
+        // non-string values for e.detail.  They're whitelisted by site origin,
+        // so we compare on originNoSuffix in order to avoid other origin attributes
+        // that are not relevant here, such as containers or private browsing.
+        let objectsAllowed = this._getWhitelistedPrincipals().some(
+          whitelisted => principal.originNoSuffix == whitelisted.originNoSuffix
+        );
+        if (!objectsAllowed) {
+          console.error(
+            "WebChannelMessageToChrome sent with an object from a non-whitelisted principal"
+          );
+          return;
+        }
+      }
+
+      let eventTarget =
+        e.target instanceof Ci.nsIDOMWindow
+          ? null
+          : ContentDOMReference.get(e.target);
+      this.sendAsyncMessage("WebChannelMessageToChrome", {
+        contentData: e.detail,
+        eventTarget,
+        principal,
+      });
+    } else {
+      console.error("WebChannel message failed. No message detail.");
+    }
+  }
+
+  _onMessageToContent(msg) {
+    if (msg.data && this.contentWindow) {
+      // msg.objects.eventTarget will be defined if sending a response to
+      // a WebChannelMessageToChrome event. An unsolicited send
+      // may not have an eventTarget defined, in this case send to the
+      // main content window.
+      let { eventTarget, principal } = msg.data;
+      if (!eventTarget) {
+        eventTarget = this.contentWindow;
+      } else {
+        eventTarget = ContentDOMReference.resolve(eventTarget);
+      }
+      if (!eventTarget) {
+        console.error("WebChannel message failed. No target.");
+        return;
+      }
+
+      // Use nodePrincipal if available, otherwise fallback to document principal.
+      let targetPrincipal =
+        eventTarget instanceof Ci.nsIDOMWindow
+          ? eventTarget.document.nodePrincipal
+          : eventTarget.nodePrincipal;
+
+      if (principal.subsumes(targetPrincipal)) {
+        let targetWindow = this.contentWindow;
+        eventTarget.dispatchEvent(
+          new targetWindow.CustomEvent("WebChannelMessageToContent", {
+            detail: Cu.cloneInto(
+              {
+                id: msg.data.id,
+                message: msg.data.message,
+              },
+              targetWindow
+            ),
+          })
+        );
+      } else {
+        console.error("WebChannel message failed. Principal mismatch.");
+      }
+    } else {
+      console.error("WebChannel message failed. No message data.");
+    }
+  }
+}