net/proxy/dhcp_proxy_script_fetcher_factory.h

   1 // Copyright (c) 2012 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 NET_PROXY_DHCP_SCRIPT_FETCHER_FACTORY_H_
   6 #define NET_PROXY_DHCP_SCRIPT_FETCHER_FACTORY_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/singleton.h"
  10 #include "net/base/completion_callback.h"
  11 #include "net/base/net_export.h"
  12 #include "net/proxy/dhcp_proxy_script_fetcher.h"
  13
  14 namespace net {
  15
  16 class URLRequestContext;
  17
  18 // Factory object for creating the appropriate concrete base class of
  19 // DhcpProxyScriptFetcher for your operating system and settings.
  20 //
  21 // You might think we could just implement a DHCP client at the protocol
  22 // level and have cross-platform support for retrieving PAC configuration
  23 // from DHCP, but unfortunately the DHCP protocol assumes there is a single
  24 // client per machine (specifically per network interface card), and there
  25 // is an implicit state machine between the client and server, so adding a
  26 // second client to the machine would not be advisable (see e.g. some
  27 // discussion of what can happen at this URL:
  28 // http://www.net.princeton.edu/multi-dhcp-one-interface-handling.html).
  29 //
  30 // Therefore, we have platform-specific implementations, and so we use
  31 // this factory to select the right one.
  32 class NET_EXPORT DhcpProxyScriptFetcherFactory {
  33  public:
  34   // Creates a new factory object with default settings.
  35   DhcpProxyScriptFetcherFactory();
  36
  37   // url_request_context must be valid and its lifetime must exceed that of the
  38   // returned DhcpProxyScriptFetcher.
  39   //
  40   // Note that while a request is in progress, the fetcher may be holding a
  41   // reference to |url_request_context|. Be careful not to create cycles
  42   // between the fetcher and the context; you can break such cycles by calling
  43   // Cancel().
  44   scoped_ptr<DhcpProxyScriptFetcher> Create(
  45       URLRequestContext* url_request_context);
  46
  47   // Attempts to enable/disable the DHCP WPAD feature.  Does nothing
  48   // if |IsSupported()| returns false.
  49   //
  50   // The default is |enabled() == true|.
  51   void set_enabled(bool enabled);
  52
  53   // Returns true if the DHCP WPAD feature is enabled.  Always returns
  54   // false if |IsSupported()| is false.
  55   bool enabled() const;
  56
  57   // Returns true if the DHCP WPAD feature is supported on the current
  58   // operating system.
  59   static bool IsSupported();
  60
  61  private:
  62   bool feature_enabled_;
  63
  64   DISALLOW_COPY_AND_ASSIGN(DhcpProxyScriptFetcherFactory);
  65 };
  66
  67 }  // namespace net
  68
  69 #endif  // NET_PROXY_DHCP_SCRIPT_FETCHER_FACTORY_H_