Implement extension:// protocol.

chrome/browser/extensions/extension_protocol.cc

+// Copyright (c) 2006-2008 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/extensions/extension_protocol.h"
+
+#include "base/string_util.h"
+#include "chrome/browser/net/chrome_url_request_context.h"
+#include "googleurl/src/url_util.h"
+#include "net/base/net_util.h"
+#include "net/url_request/url_request_file_job.h"
+
+static const char kExtensionURLScheme[] = "chrome-extension";
+
+FilePath GetPathForExtensionResource(const FilePath& extension_path,
+                                     const std::string& url_path) {
+  DCHECK(extension_path.IsAbsolute());
+  DCHECK(url_path.length() > 0 && url_path[0] == '/');
+
+  // Build up a file:// URL and convert that back to a FilePath.  This avoids
+  // URL encoding and path separator issues.
+
+  // Convert the extension's root to a file:// URL.
+  GURL extension_url = net::FilePathToFileURL(extension_path);
+  if (!extension_url.is_valid())
+    return FilePath();
+
+  // Append the requested path.
+  GURL::Replacements replacements;
+  std::string new_path(extension_url.path());
+  new_path += url_path;
+  replacements.SetPathStr(new_path);
+  GURL file_url = extension_url.ReplaceComponents(replacements);
+  if (!file_url.is_valid())
+    return FilePath();
+
+  // Convert the result back to a FilePath.
+  FilePath ret_val;
+  if (!net::FileURLToFilePath(file_url, &ret_val))
+    return FilePath();
+
+  // Double-check that the path we ended up with is actually inside the
+  // extension root.
+  if (!extension_path.Contains(ret_val))
+    return FilePath();
+
+  return ret_val;
+}
+
+// Creates a URLRequestJob instance for an extension URL. This is the factory
+// function that is registered with URLRequest.
+static URLRequestJob* CreateURLRequestJob(URLRequest* request,
+                                          const std::string& scheme) {
+  ChromeURLRequestContext* context =
+      static_cast<ChromeURLRequestContext*>(request->context());
+
+  FilePath extension_path = context->GetPathForExtension(request->url().host());
+  if (extension_path.value().empty())
+    return NULL;
+
+  FilePath path = GetPathForExtensionResource(extension_path,
+                                              request->url().path());
+  if (path.value().empty())
+    return NULL;
+
+  return new URLRequestFileJob(request, path);
+}
+
+void RegisterExtensionProtocol() {
+  // Being a standard scheme allows us to resolve relative paths
+  url_util::AddStandardScheme(kExtensionURLScheme);
+
+  URLRequest::RegisterProtocolFactory(kExtensionURLScheme,
+                                      &CreateURLRequestJob);
+}