From a009c49f938e7ae15ea5882e1b0f73bc01c7aca5 Mon Sep 17 00:00:00 2001
From: Eden Chuang <echuang@mozilla.com>
Date: Mon, 23 Sep 2024 09:07:52 +0000
Subject: [PATCH] Bug 1843001 - Allow fetch() to localhost in Workers while
 network is offline. r=asuth,necko-reviewers,valentin

Differential Revision: https://phabricator.services.mozilla.com/D198374
---
 dom/fetch/FetchService.cpp                    | 37 +++++++++----
 dom/fetch/FetchService.h                      |  2 +
 dom/serviceworkers/test/mochitest-common.toml |  7 +++
 .../test/offline_fetch/index.html             |  4 ++
 .../test/offline_fetch/register.html          | 16 ++++++
 dom/serviceworkers/test/offline_fetch/sw.js   |  3 ++
 .../test/offline_fetch/unregister.html        | 12 +++++
 .../test/test_offline_localhost_fetch.html    | 54 +++++++++++++++++++
 8 files changed, 124 insertions(+), 11 deletions(-)
 create mode 100644 dom/serviceworkers/test/offline_fetch/index.html
 create mode 100644 dom/serviceworkers/test/offline_fetch/register.html
 create mode 100644 dom/serviceworkers/test/offline_fetch/sw.js
 create mode 100644 dom/serviceworkers/test/offline_fetch/unregister.html
 create mode 100644 dom/serviceworkers/test/test_offline_localhost_fetch.html

diff --git a/dom/fetch/FetchService.cpp b/dom/fetch/FetchService.cpp
index 3d11221493fd..7e0836234960 100644
--- a/dom/fetch/FetchService.cpp
+++ b/dom/fetch/FetchService.cpp
@@ -297,6 +297,18 @@ RefPtr<FetchServicePromises> FetchService::FetchInstance::Fetch() {
   return mPromises;
 }
 
+bool FetchService::FetchInstance::IsLocalHostFetch() const {
+  if (!mPrincipal) {
+    return false;
+  }
+  bool res;
+  nsresult rv = mPrincipal->GetIsLoopbackHost(&res);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return false;
+  }
+  return res;
+}
+
 void FetchService::FetchInstance::Cancel() {
   MOZ_ASSERT(XRE_IsParentProcess());
   MOZ_ASSERT(NS_IsMainThread());
@@ -778,12 +790,15 @@ NS_IMETHODIMP FetchService::Observe(nsISupports* aSubject, const char* aTopic,
     mOffline = false;
   } else {
     mOffline = true;
-    // Network is offline, cancel running fetchs.
-    for (auto it = mFetchInstanceTable.begin(), end = mFetchInstanceTable.end();
-         it != end; ++it) {
-      it->GetData()->Cancel();
-    }
-    mFetchInstanceTable.Clear();
+    // Network is offline, cancel the running fetch that is not to local server.
+    mFetchInstanceTable.RemoveIf([](auto& entry) {
+      bool res = entry.Data()->IsLocalHostFetch();
+      if (res) {
+        return false;
+      }
+      entry.Data()->Cancel();
+      return true;
+    });
   }
   return NS_OK;
 }
@@ -795,11 +810,6 @@ RefPtr<FetchServicePromises> FetchService::Fetch(FetchArgs&& aArgs) {
   FETCH_LOG(("FetchService::Fetch (%s)", aArgs.is<NavigationPreloadArgs>()
                                              ? "NavigationPreload"
                                              : "WorkerFetch"));
-  if (mOffline) {
-    FETCH_LOG(("FetchService::Fetch network offline"));
-    return NetworkErrorResponse(NS_ERROR_OFFLINE, aArgs);
-  }
-
   // Create FetchInstance
   RefPtr<FetchInstance> fetch = MakeRefPtr<FetchInstance>();
 
@@ -810,6 +820,11 @@ RefPtr<FetchServicePromises> FetchService::Fetch(FetchArgs&& aArgs) {
     return NetworkErrorResponse(rv, fetch->Args());
   }
 
+  if (mOffline && !fetch->IsLocalHostFetch()) {
+    FETCH_LOG(("FetchService::Fetch network offline"));
+    return NetworkErrorResponse(NS_ERROR_OFFLINE, fetch->Args());
+  }
+
   // Call FetchInstance::Fetch() to start an asynchronous fetching.
   RefPtr<FetchServicePromises> promises = fetch->Fetch();
   MOZ_ASSERT(promises);
diff --git a/dom/fetch/FetchService.h b/dom/fetch/FetchService.h
index f4a5d7943b8c..15faab4b0aa0 100644
--- a/dom/fetch/FetchService.h
+++ b/dom/fetch/FetchService.h
@@ -171,6 +171,8 @@ class FetchService final : public nsIObserver {
 
     void Cancel();
 
+    bool IsLocalHostFetch() const;
+
     /* FetchDriverObserver interface */
     void OnResponseEnd(FetchDriverObserver::EndReason aReason,
                        JS::Handle<JS::Value> aReasonDetails) override;
diff --git a/dom/serviceworkers/test/mochitest-common.toml b/dom/serviceworkers/test/mochitest-common.toml
index b29e01f3742d..38856337d2c5 100644
--- a/dom/serviceworkers/test/mochitest-common.toml
+++ b/dom/serviceworkers/test/mochitest-common.toml
@@ -208,6 +208,10 @@ support-files = [
   "onmessageerror_worker.js",
   "pref/fetch_nonexistent_file.html",
   "pref/intercept_nonexistent_file_sw.js",
+  "offline_fetch/register.html",
+  "offline_fetch/index.html",
+  "offline_fetch/unregister.html",
+  "offline_fetch/sw.js",
 ]
 
 ["test_abrupt_completion.html"]
@@ -338,6 +342,9 @@ skip-if = ["os == 'linux' && bits == 64 && debug"] # Bug 1749068
 ["test_not_intercept_plugin.html"]
 skip-if = ["serviceworker_e10s"] # leaks InterceptedHttpChannel and others things
 
+["test_offline_localhost_fetch.html"]
+skip-if = ["os == 'android'"]
+
 ["test_onmessageerror.html"]
 skip-if = ["xorigin"] # Bug 1792790
 
diff --git a/dom/serviceworkers/test/offline_fetch/index.html b/dom/serviceworkers/test/offline_fetch/index.html
new file mode 100644
index 000000000000..a435548443aa
--- /dev/null
+++ b/dom/serviceworkers/test/offline_fetch/index.html
@@ -0,0 +1,4 @@
+<!DOCTYPE html>
+<script>
+  window.parent.postMessage({status: "done"}, "*");
+</script>
diff --git a/dom/serviceworkers/test/offline_fetch/register.html b/dom/serviceworkers/test/offline_fetch/register.html
new file mode 100644
index 000000000000..667b2b712ec1
--- /dev/null
+++ b/dom/serviceworkers/test/offline_fetch/register.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<script>
+  function ok(v, msg) {
+    window.parent.postMessage({status: "ok", result: !!v, message: msg}, "*");
+  }
+
+  function done(reg) {
+    ok(reg.active, "The active worker should be available.");
+    window.parent.postMessage({status: "registrationdone"}, "*");
+  }
+
+  navigator.serviceWorker.ready.then(reg => {
+    done(reg);
+  });
+  navigator.serviceWorker.register("sw.js", {scope: "."});
+</script>
diff --git a/dom/serviceworkers/test/offline_fetch/sw.js b/dom/serviceworkers/test/offline_fetch/sw.js
new file mode 100644
index 000000000000..f1221274ef93
--- /dev/null
+++ b/dom/serviceworkers/test/offline_fetch/sw.js
@@ -0,0 +1,3 @@
+self.addEventListener("fetch", function (event) {
+  event.respondWith(fetch(event.request));
+});
diff --git a/dom/serviceworkers/test/offline_fetch/unregister.html b/dom/serviceworkers/test/offline_fetch/unregister.html
new file mode 100644
index 000000000000..1f13508fa700
--- /dev/null
+++ b/dom/serviceworkers/test/offline_fetch/unregister.html
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<script>
+  navigator.serviceWorker.getRegistration(".").then(function(registration) {
+    registration.unregister().then(function(success) {
+      if (success) {
+        window.parent.postMessage({status: "unregistrationdone"}, "*");
+      }
+    }, function(e) {
+      dump("Unregistering the SW failed with " + e + "\n");
+    });
+  });
+</script>
diff --git a/dom/serviceworkers/test/test_offline_localhost_fetch.html b/dom/serviceworkers/test/test_offline_localhost_fetch.html
new file mode 100644
index 000000000000..81b37f20eccb
--- /dev/null
+++ b/dom/serviceworkers/test/test_offline_localhost_fetch.html
@@ -0,0 +1,54 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1843001</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<iframe></iframe>
+<script>
+
+const basePath = window.location.pathname.replace(/\/[^\/]*$/, '/');
+const localhostBaseURL = "http://127.0.0.1:8888" + basePath;
+
+  var iframe;
+  function runTest() {
+    iframe = document.querySelector("iframe");
+    iframe.src = localhostBaseURL + "offline_fetch/register.html";
+    var ios;
+    window.onmessage = function(e) {
+      if (e.data.status == "ok") {
+        ok(e.data.result, e.data.message);
+      } else if (e.data.status == "registrationdone") {
+        ios = SpecialPowers.Cc["@mozilla.org/network/io-service;1"]
+                           .getService(SpecialPowers.Ci.nsIIOService);
+        ios.offline = true;
+        iframe.src = localhostBaseURL + "offline_fetch/index.html";
+      } else if (e.data.status == "done") {
+        ios.offline = false;
+        iframe.src = localhostBaseURL + "offline_fetch/unregister.html";
+      } else if (e.data.status == "unregistrationdone") {
+        window.onmessage = null;
+        ok(true, "Test finished successfully");
+        SimpleTest.finish();
+      }
+    };
+  }
+
+  SimpleTest.waitForExplicitFinish();
+  onload = function() {
+    SpecialPowers.pushPrefEnv({"set": [
+      ["dom.serviceWorkers.exemptFromPerDomainMax", true],
+      ["dom.serviceWorkers.enabled", true],
+      ["dom.serviceWorkers.testing.enabled", true],
+    ]}, runTest);
+  };
+</script>
+</pre>
+</body>
+</html>