content/public/browser/url_data_source.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_PUBLIC_BROWSER_URL_DATA_SOURCE_H_
   6 #define CONTENT_PUBLIC_BROWSER_URL_DATA_SOURCE_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "content/common/content_export.h"
  12
  13 namespace base {
  14 class MessageLoop;
  15 class RefCountedMemory;
  16 }
  17
  18 namespace net {
  19 class URLRequest;
  20 }
  21
  22 namespace content {
  23 class BrowserContext;
  24
  25 // A URLDataSource is an object that can answer requests for WebUI data
  26 // asynchronously. An implementation of URLDataSource should handle calls to
  27 // StartDataRequest() by starting its (implementation-specific) asynchronous
  28 // request for the data, then running the callback given in that method to
  29 // notify.
  30 class CONTENT_EXPORT URLDataSource {
  31  public:
  32   // Adds a URL data source to |browser_context|.
  33   static void Add(BrowserContext* browser_context, URLDataSource* source);
  34
  35   virtual ~URLDataSource() {}
  36
  37   // The name of this source.
  38   // E.g., for favicons, this could be "favicon", which results in paths for
  39   // specific resources like "favicon/34" getting sent to this source.
  40   virtual std::string GetSource() const = 0;
  41
  42   // Used by StartDataRequest so that the child class can return the data when
  43   // it's available.
  44   typedef base::Callback<void(base::RefCountedMemory*)> GotDataCallback;
  45
  46   // Called by URLDataSource to request data at |path|. The string parameter is
  47   // the path of the request. The child class should run |callback| when the
  48   // data is available or if the request could not be satisfied. This can be
  49   // called either in this callback or asynchronously with the response.
  50   virtual void StartDataRequest(const std::string& path,
  51                                 int render_process_id,
  52                                 int render_view_id,
  53                                 const GotDataCallback& callback) = 0;
  54
  55   // Return the mimetype that should be sent with this response, or empty
  56   // string to specify no mime type.
  57   virtual std::string GetMimeType(const std::string& path) const = 0;
  58
  59   // The following methods are all called on the IO thread.
  60
  61   // Returns the MessageLoop on which the delegate wishes to have
  62   // StartDataRequest called to handle the request for |path|. The default
  63   // implementation returns BrowserThread::UI. If the delegate does not care
  64   // which thread StartDataRequest is called on, this should return NULL. It may
  65   // be beneficial to return NULL for requests that are safe to handle directly
  66   // on the IO thread.  This can improve performance by satisfying such requests
  67   // more rapidly when there is a large amount of UI thread contention. Or the
  68   // delegate can return a specific thread's Messageloop if they wish.
  69   virtual base::MessageLoop* MessageLoopForRequestPath(
  70       const std::string& path) const;
  71
  72   // Returns true if the URLDataSource should replace an existing URLDataSource
  73   // with the same name that has already been registered. The default is true.
  74   //
  75   // WARNING: this is invoked on the IO thread.
  76   //
  77   // TODO: nuke this and convert all callers to not replace.
  78   virtual bool ShouldReplaceExistingSource() const;
  79
  80   // Returns true if responses from this URLDataSource can be cached.
  81   virtual bool AllowCaching() const;
  82
  83   // If you are overriding this, then you have a bug.
  84   // It is not acceptable to disable content-security-policy on chrome:// pages
  85   // to permit functionality excluded by CSP, such as inline script.
  86   // Instead, you must go back and change your WebUI page so that it is
  87   // compliant with the policy. This typically involves ensuring that all script
  88   // is delivered through the data manager backend. Talk to tsepez for more
  89   // info.
  90   virtual bool ShouldAddContentSecurityPolicy() const;
  91
  92   // It is OK to override the following two methods to a custom CSP directive
  93   // thereby slightly reducing the protection applied to the page.
  94
  95   // By default, "object-src 'none';" is added to CSP. Override to change this.
  96   virtual std::string GetContentSecurityPolicyObjectSrc() const;
  97   // By default, "frame-src 'none';" is added to CSP. Override to change this.
  98   virtual std::string GetContentSecurityPolicyFrameSrc() const;
  99
 100   // By default, the "X-Frame-Options: DENY" header is sent. To stop this from
 101   // happening, return false. It is OK to return false as needed.
 102   virtual bool ShouldDenyXFrameOptions() const;
 103
 104   // By default, only chrome: and chrome-devtools: requests are allowed.
 105   // Override in specific WebUI data sources to enable for additional schemes or
 106   // to implement fancier access control.  Typically used in concert with
 107   // ContentBrowserClient::GetAdditionalWebUISchemes() to permit additional
 108   // WebUI scheme support for an embedder.
 109   virtual bool ShouldServiceRequest(const net::URLRequest* request) const;
 110
 111   // Called to inform the source that StartDataRequest() will be called soon.
 112   // Gives the source an opportunity to rewrite |path| to incorporate extra
 113   // information from the URLRequest prior to serving.
 114   virtual void WillServiceRequest(
 115       const net::URLRequest* request,
 116       std::string* path) const {}
 117 };
 118
 119 }  // namespace content
 120
 121 #endif  // CONTENT_PUBLIC_BROWSER_URL_DATA_SOURCE_H_