Bug 1405286: Part 3 - Test that filterResponseData from cached onHeadersReceived doesn't crash. r=mixedpuppy

It currently isn't possible to suspend a channel from onHeadersReceived for a
cached response. And since it's not possible to add a new stream filter after
a response has started, adding a stream filter at that point will crash if the
channel is still registered.

This test is a basic sanity check for that scenario.

MozReview-Commit-ID: ALYUtxX7mci

--HG--
extra : rebase_source : 120889fd8f9edd097a7dae807b54eb3fd283f0f6

toolkit/components/extensions/test/mochitest/test_ext_webrequest_responseBody.html

@@ -407,6 +407,48 @@ add_task(async function() {
   await extension.unload();
 });
 
+// Test that registering a listener for a cached response does not cause a crash.
+add_task(async function test_cachedResponse() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onHeadersReceived.addListener(data => {
+        let filter = browser.webRequest.filterResponseData(data.requestId);
+
+        filter.onstop = event => {
+          filter.close();
+        };
+        filter.ondata = event => {
+          filter.write(event.data);
+        };
+
+        if (data.fromCache) {
+          browser.test.sendMessage("from-cache");
+        }
+      }, {
+        urls: ["http://mochi.test/*/file_sample.html?r=*"],
+      },
+      ["blocking"]);
+    },
+
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "http://mochi.test/",
+      ],
+    },
+  });
+
+  await extension.startup();
+
+  let url = `file_sample.html?r=${Math.random()}`;
+  await fetch(url);
+  await fetch(url);
+  await extension.awaitMessage("from-cache");
+
+  await extension.unload();
+});
+
 add_task(async function test_permissions() {
   let extension = ExtensionTestUtils.loadExtension({
     background() {

toolkit/components/extensions/webrequest/ChannelWrapper.cpp

@@ -630,6 +630,12 @@ ChannelWrapper::GetFrameAncestors(nsILoadInfo* aLoadInfo, nsTArray<dom::MozFrame
 void
 ChannelWrapper::RegisterTraceableChannel(const WebExtensionPolicy& aAddon, nsITabParent* aTabParent)
 {
+  // We can't attach new listeners after the response has started, so don't
+  // bother registering anything.
+  if (mResponseStarted) {
+    return;
+  }
+
   mAddonEntries.Put(aAddon.Id(), aTabParent);
   if (!mChannelEntry) {
     mChannelEntry = WebRequestService::GetSingleton().RegisterChannel(this);
@@ -914,6 +920,7 @@ ChannelWrapper::RequestListener::OnStartRequest(nsIRequest *request, nsISupports
   MOZ_ASSERT(mOrigStreamListener, "Should have mOrigStreamListener");
 
   mChannelWrapper->mChannelEntry = nullptr;
+  mChannelWrapper->mResponseStarted = true;
   mChannelWrapper->ErrorCheck();
   mChannelWrapper->FireEvent(NS_LITERAL_STRING("start"));
 

toolkit/components/extensions/webrequest/ChannelWrapper.h

@@ -288,6 +288,7 @@ private:
   bool mAddedStreamListener = false;
   bool mFiredErrorEvent = false;
   bool mSuspended = false;
+  bool mResponseStarted = false;
 
 
   nsInterfaceHashtable<nsPtrHashKey<const nsAtom>, nsITabParent> mAddonEntries;

toolkit/modules/addons/WebRequest.jsm

@@ -166,7 +166,7 @@ class ResponseHeaderChanger extends HeaderChanger {
 }
 
 const MAYBE_CACHED_EVENTS = new Set([
-  "onResponseStarted", "onBeforeRedirect", "onCompleted", "onErrorOccurred",
+  "onResponseStarted", "onHeadersReceived", "onBeforeRedirect", "onCompleted", "onErrorOccurred",
 ]);
 
 const OPTIONAL_PROPERTIES = [