Adds support for the DHCP portion of the WPAD (proxy auto-discovery) protocol.

net/proxy/dhcp_proxy_script_fetcher_win.h

+// Copyright (c) 2011 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.
+
+#ifndef NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_
+#define NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_
+#pragma once
+
+#include "base/memory/ref_counted.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/timer.h"
+#include "net/proxy/dhcp_proxy_script_fetcher.h"
+
+#include <list>
+#include <set>
+#include <string>
+
+namespace net {
+
+class DhcpProxyScriptAdapterFetcher;
+class URLRequestContext;
+
+// Windows-specific implementation.
+class WindowsDhcpProxyScriptFetcher
+    : public DhcpProxyScriptFetcher,
+      public base::NonThreadSafe {
+ public:
+  // Creates a WindowsDhcpProxyScriptFetcher that issues requests through
+  // |url_request_context|. |url_request_context| must remain valid for
+  // the lifetime of WindowsDhcpProxyScriptFetcher.
+  explicit WindowsDhcpProxyScriptFetcher(
+      URLRequestContext* url_request_context);
+  virtual ~WindowsDhcpProxyScriptFetcher();
+
+  // DhcpProxyScriptFetcher implementation.
+  int Fetch(string16* utf16_text, CompletionCallback* callback) OVERRIDE;
+  void Cancel() OVERRIDE;
+  URLRequestContext* GetRequestContext() const OVERRIDE;
+  GURL GetPacURL() const OVERRIDE;
+  std::string GetFetcherName() const OVERRIDE;
+
+  // Adds to |adapter_names| the name of each network adapter on this machine
+  // that has DHCP enabled and is not a loop-back adapter. Returns false
+  // on error.
+  static bool GetCandidateAdapterNames(std::set<std::string>* adapter_names);
+
+ protected:
+  // Event/state transition handlers
+  void CancelImpl(bool clear_fetchers);
+  void OnFetcherDone(int result);
+  void OnWaitTimer();
+  void TransitionToDone();
+
+  // Virtual methods introduced to allow unit testing.
+  virtual DhcpProxyScriptAdapterFetcher* ImplCreateAdapterFetcher();
+  virtual bool ImplGetCandidateAdapterNames(
+      std::set<std::string>* adapter_names);
+  virtual int ImplGetMaxWaitMs();
+
+  // This is the outer state machine for fetching PAC configuration from
+  // DHCP.  It relies for sub-states on the state machine of the
+  // DhcpProxyScriptAdapterFetcher class.
+  //
+  // The goal of the implementation is to the following work in parallel
+  // for all network adapters that are using DHCP:
+  // a) Try to get the PAC URL configured in DHCP;
+  // b) If one is configured, try to fetch the PAC URL.
+  // c) Once this is done for all adapters, or a timeout has passed after
+  //    it has completed for the fastest adapter, return the PAC file
+  //    available for the most preferred network adapter, if any.
+  //
+  // The state machine goes from START->NO_RESULTS when it creates
+  // and starts an DhcpProxyScriptAdapterFetcher for each adapter.  It goes
+  // from NO_RESULTS->SOME_RESULTS when it gets the first result; at this
+  // point a wait timer is started.  It goes from SOME_RESULTS->DONE in
+  // two cases: All results are known, or the wait timer expired.  A call
+  // to Cancel() will also go straight to DONE from any state.  Any
+  // way the DONE state is entered, we will at that point cancel any
+  // outstanding work and return the best known PAC script or the empty
+  // string.
+  //
+  // The state machine is reset for each Fetch(), a call to which is
+  // only valid in states START and DONE, as only one Fetch() is
+  // allowed to be outstanding at any given time.
+  enum State {
+    STATE_START,
+    STATE_NO_RESULTS,
+    STATE_SOME_RESULTS,
+    STATE_DONE,
+  };
+
+  // Current state of this state machine.
+  State state_;
+
+  // List, in Windows' network adapter preference order, of
+  // DhcpProxyScriptAdapterFetcher objects that are or were attempting
+  // to fetch a PAC file based on DHCP configuration.
+  typedef std::list<scoped_refptr<DhcpProxyScriptAdapterFetcher>> FetcherList;
+  FetcherList fetchers_;
+
+  // Callback invoked when any fetcher completes.
+  CompletionCallbackImpl<WindowsDhcpProxyScriptFetcher> fetcher_callback_;
+
+  // Number of fetchers we are waiting for.
+  int num_pending_fetchers_;
+
+  // Lets our client know we're done. Not valid in states START or DONE.
+  CompletionCallback* client_callback_;
+
+  // Pointer to string we will write results to. Not valid in states
+  // START and DONE.
+  string16* destination_string_;
+
+  // PAC URL retrieved from DHCP, if any. Valid only in state STATE_DONE.
+  GURL pac_url_;
+
+  base::OneShotTimer<WindowsDhcpProxyScriptFetcher> wait_timer_;
+
+  URLRequestContext* url_request_context_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(WindowsDhcpProxyScriptFetcher);
+};
+
+}  // namespace net
+
+#endif  // NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_