// Copyright (c) 2012 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_
#include <set>
#include <string>
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_vector.h"
#include "base/message_loop/message_loop_proxy.h"
#include "base/threading/non_thread_safe.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "net/proxy/dhcp_proxy_script_fetcher.h"
namespace base {
class SequencedWorkerPool;
}
namespace net {
class DhcpProxyScriptAdapterFetcher;
class URLRequestContext;
// Windows-specific implementation.
class NET_EXPORT_PRIVATE DhcpProxyScriptFetcherWin
: public DhcpProxyScriptFetcher,
public base::SupportsWeakPtr<DhcpProxyScriptFetcherWin>,
NON_EXPORTED_BASE(public base::NonThreadSafe) {
public:
// Creates a DhcpProxyScriptFetcherWin that issues requests through
// |url_request_context|. |url_request_context| must remain valid for
// the lifetime of DhcpProxyScriptFetcherWin.
explicit DhcpProxyScriptFetcherWin(URLRequestContext* url_request_context);
virtual ~DhcpProxyScriptFetcherWin();
// DhcpProxyScriptFetcher implementation.
int Fetch(base::string16* utf16_text,
const net::CompletionCallback& callback) OVERRIDE;
void Cancel() OVERRIDE;
const GURL& GetPacURL() const OVERRIDE;
std::string GetFetcherName() const OVERRIDE;
// Sets |adapter_names| to contain 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:
int num_pending_fetchers() const;
URLRequestContext* url_request_context() const;
scoped_refptr<base::TaskRunner> GetTaskRunner();
// This inner class encapsulate work done on a worker pool thread.
// The class calls GetCandidateAdapterNames, which can take a couple of
// hundred milliseconds.
class NET_EXPORT_PRIVATE AdapterQuery
: public base::RefCountedThreadSafe<AdapterQuery> {
public:
AdapterQuery();
virtual ~AdapterQuery();
// This is the method that runs on the worker pool thread.
void GetCandidateAdapterNames();
// This set is valid after GetCandidateAdapterNames has
// been run. Its lifetime is scoped by this object.
const std::set<std::string>& adapter_names() const;
protected:
// Virtual method introduced to allow unit testing.
virtual bool ImplGetCandidateAdapterNames(
std::set<std::string>* adapter_names);
private:
// This is constructed on the originating thread, then used on the
// worker thread, then used again on the originating thread only when
// the task has completed on the worker thread. No locking required.
std::set<std::string> adapter_names_;
DISALLOW_COPY_AND_ASSIGN(AdapterQuery);
};
// Virtual methods introduced to allow unit testing.
virtual DhcpProxyScriptAdapterFetcher* ImplCreateAdapterFetcher();
virtual AdapterQuery* ImplCreateAdapterQuery();
virtual base::TimeDelta ImplGetMaxWait();
virtual void ImplOnGetCandidateAdapterNamesDone() {}
private:
// Event/state transition handlers
void CancelImpl();
void OnGetCandidateAdapterNamesDone(scoped_refptr<AdapterQuery> query);
void OnFetcherDone(int result);
void OnWaitTimer();
void TransitionToDone();
// 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->WAIT_ADAPTERS when it starts a
// worker thread to get the list of adapters with DHCP enabled.
// It then goes from WAIT_ADAPTERS->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_WAIT_ADAPTERS,
STATE_NO_RESULTS,
STATE_SOME_RESULTS,
STATE_DONE,
};
// Current state of this state machine.
State state_;
// Vector, in Windows' network adapter preference order, of
// DhcpProxyScriptAdapterFetcher objects that are or were attempting
// to fetch a PAC file based on DHCP configuration.
typedef ScopedVector<DhcpProxyScriptAdapterFetcher> FetcherVector;
FetcherVector fetchers_;
// 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.
net::CompletionCallback callback_;
// Pointer to string we will write results to. Not valid in states
// START and DONE.
base::string16* destination_string_;
// PAC URL retrieved from DHCP, if any. Valid only in state STATE_DONE.
GURL pac_url_;
base::OneShotTimer<DhcpProxyScriptFetcherWin> wait_timer_;
URLRequestContext* const url_request_context_;
// NULL or the AdapterQuery currently in flight.
scoped_refptr<AdapterQuery> last_query_;
// Time |Fetch()| was last called, 0 if never.
base::TimeTicks fetch_start_time_;
// Worker pool we use for all DHCP lookup tasks.
scoped_refptr<base::SequencedWorkerPool> worker_pool_;
DISALLOW_IMPLICIT_CONSTRUCTORS(DhcpProxyScriptFetcherWin);
};
} // namespace net
#endif // NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_