Handle online and offline redirects via interceptor and offline scheme

chrome/browser/android/offline_pages/offline_page_request_handler.cc

Index: chrome/browser/android/offline_pages/offline_page_request_handler.cc
diff --git a/chrome/browser/android/offline_pages/offline_page_request_handler.cc b/chrome/browser/android/offline_pages/offline_page_request_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..dc7d992a27aa0cd1529e4c494c1b0a6402f1d68d
--- /dev/null
+++ b/chrome/browser/android/offline_pages/offline_page_request_handler.cc
@@ -0,0 +1,195 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/android/offline_pages/offline_page_request_handler.h"
+
+#include "base/macros.h"
+#include "chrome/browser/android/offline_pages/offline_page_utils.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/common/url_constants.h"
+#include "components/offline_pages/offline_page_feature.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/network_change_notifier.h"
+#include "net/url_request/url_request.h"
+#include "net/url_request/url_request_redirect_job.h"
+
+namespace offline_pages {
+
+namespace {
+
+int kUserDataKey;  // Only address is used.
+
+// An interceptor to hijack requests and potentially service them based on
+// their offline information.
+class OfflinePageRequestInterceptor : public net::URLRequestInterceptor {
+ public:
+  explicit OfflinePageRequestInterceptor(void* profile_id)
+      : profile_id_(profile_id) { }
+  ~OfflinePageRequestInterceptor() override {}
+
+ private:
+  // Overrides from net::URLRequestInterceptor:
+  net::URLRequestJob* MaybeInterceptRequest(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate) const override {
+    OfflinePageRequestHandler* handler = OfflinePageRequestHandler::GetHandler(
+        request);
+    if (!handler)
+      return nullptr;
+    return handler->MaybeCreateJob(request, network_delegate, profile_id_);
+  }
+
+  // The profile for processing Drive accesses. Should not be NULL.
+  void* profile_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageRequestInterceptor);
+};
+
+// Called on IO thread after a redirect URL is obtained.
+void DidGetRedirectURL(const GURL& redirect_url,
+                       base::WeakPtr<OfflinePageRequestRedirectJob> job) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+
+  if (!job)
+    return;
+
+  if (redirect_url.is_valid())
+    job->SetRedirectURL(redirect_url);
+  else
+    job->FallbackToDefault();
+}
+
+// Called on UI thread after an offline URL is obtained.
+void DidGetOfflineURL(base::WeakPtr<OfflinePageRequestRedirectJob> job,
+                      const GURL& online_url,
+                      const GURL& offline_file_url) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  // DidGetRedirectURL should always be called even when no offline URL is
+  // found.
+  GURL redirect_url;
+  if (offline_file_url.is_valid()) {
+    redirect_url =
+        GURL(chrome::kOfflinePageScheme + std::string(":") + online_url.spec());
+  }
+
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&DidGetRedirectURL, redirect_url, job));
+}
+
+}  // namespace
+
+// static
+void OfflinePageRequestHandler::InitializeHandler(
+    net::URLRequest* request,
+    content::ResourceType resource_type) {
+  if (!IsOfflinePagesEnabled())
+    return;
+
+  // Ignore the request not for the main resource file.
+  if (resource_type != content::RESOURCE_TYPE_MAIN_FRAME)
+    return;
+
+  // TODO(jianli): Ignore other requests that will not involve offline
+  // redirects.
+
+  // Any more precise checks to see if the request should be intercepted are
+  // asynchronous, so just create our handler in all cases.
+  std::unique_ptr<OfflinePageRequestHandler> handler(
+      new OfflinePageRequestHandler());
+  request->SetUserData(&kUserDataKey, handler.release());
+}
+
+// static
+OfflinePageRequestHandler* OfflinePageRequestHandler::GetHandler(
+    net::URLRequest* request) {
+  return static_cast<OfflinePageRequestHandler*>(
+      request->GetUserData(&kUserDataKey));
+}
+
+// static
+std::unique_ptr<net::URLRequestInterceptor>
+OfflinePageRequestHandler::CreateInterceptor(void* profile_id) {
+  if (!IsOfflinePagesEnabled())
+    return nullptr;
+
+  return std::unique_ptr<net::URLRequestInterceptor>(
+      new OfflinePageRequestInterceptor(profile_id));
+}
+
+OfflinePageRequestHandler::OfflinePageRequestHandler()
+    : weak_ptr_factory_(this) {
+}
+
+OfflinePageRequestHandler::~OfflinePageRequestHandler() {
+}
+
+void OfflinePageRequestHandler::OnPrepareToRestart() {
+  use_default_ = true;
+  redirect_job_.reset();
+}
+
+net::URLRequestJob* OfflinePageRequestHandler::MaybeCreateJob(
+    net::URLRequest* request,
+    net::NetworkDelegate* network_delegate,
+    void* profile_id) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+
+  if (use_default_)
+      return nullptr;
+
+  OfflinePageRequestRedirectJob* redirect_job =
+      new OfflinePageRequestRedirectJob(request, network_delegate, this);
+  redirect_job_ = redirect_job->GetWeakPtr();
+
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&OfflinePageRequestHandler::GetRedirectUrl,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 request->url(),
+                 profile_id));
+
+  return redirect_job_.get();
+}
+
+void OfflinePageRequestHandler::GetRedirectUrl(const GURL& url,
+                                               void* profile_id){
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  // |profile_id| needs to be checked with ProfileManager::IsValidProfile
+  // before using it.
+  if (!g_browser_process->profile_manager()->IsValidProfile(profile_id))
+    return;
+  Profile* profile = reinterpret_cast<Profile*>(profile_id);
+
+  if (net::NetworkChangeNotifier::IsOffline()) {
+    // TODO(jianli): Currently offline_url returned by GetOfflineURLForOnlineURL
+    // is the underlying file URL. We should change it to offline scheme URL and
+    // expose file path in another method.
+    OfflinePageUtils::GetOfflineURLForOnlineURL(
+        profile,
+        url,
+        base::Bind(&DidGetOfflineURL, redirect_job_, url));
+    return;
+  }
+
+  GURL redirect_url;
+  if (url.SchemeIs(chrome::kOfflinePageScheme)) {
+    GURL online_url = GURL(url.GetContent());
+    if (online_url.is_valid() && online_url.SchemeIsHTTPOrHTTPS())
+      redirect_url = online_url;
+  }
+
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&DidGetRedirectURL, redirect_url, redirect_job_));
+}
+
+}  // namespace offline_pages