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// 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.
#include <stddef.h>
#include <memory>
#include <string>
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/strings/string16.h"
#include "base/threading/thread_checker.h"
#include "base/timer/timer.h"
#include "net/base/completion_once_callback.h"
#include "net/base/net_export.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "url/gurl.h"
namespace base {
class TaskRunner;
namespace net {
class PacFileFetcher;
class URLRequestContext;
// For a given adapter, this class takes care of first doing a DHCP lookup
// to get the PAC URL, then if there is one, trying to fetch it.
class NET_EXPORT_PRIVATE DhcpPacFileAdapterFetcher
: public base::SupportsWeakPtr<DhcpPacFileAdapterFetcher> {
// |url_request_context| must outlive DhcpPacFileAdapterFetcher.
// |task_runner| will be used to post tasks to a thread.
DhcpPacFileAdapterFetcher(URLRequestContext* url_request_context,
scoped_refptr<base::TaskRunner> task_runner);
virtual ~DhcpPacFileAdapterFetcher();
// Starts a fetch. On completion (but not cancellation), |callback|
// will be invoked with the network error indicating success or failure
// of fetching a DHCP-configured PAC file on this adapter.
// On completion, results can be obtained via |GetPacScript()|, |GetPacURL()|.
// You may only call Fetch() once on a given instance of
// DhcpPacFileAdapterFetcher.
virtual void Fetch(const std::string& adapter_name,
CompletionOnceCallback callback,
const NetworkTrafficAnnotationTag traffic_annotation);
// Cancels the fetch on this adapter.
virtual void Cancel();
// Returns true if in the FINISH state (not CANCEL).
virtual bool DidFinish() const;
// Returns the network error indicating the result of the fetch. Will
// return IO_PENDING until the fetch is complete or cancelled. This is
// the same network error passed to the |callback| provided to |Fetch()|.
virtual int GetResult() const;
// Returns the contents of the PAC file retrieved. Only valid if
// |IsComplete()| is true. Returns the empty string if |GetResult()|
// returns anything other than OK.
virtual base::string16 GetPacScript() const;
// Returns the PAC URL retrieved from DHCP. Only guaranteed to be
// valid if |IsComplete()| is true. Returns an empty URL if no URL was
// configured in DHCP. May return a valid URL even if |result()| does
// not return OK (this would indicate that we found a URL configured in
// DHCP but failed to download it).
virtual GURL GetPacURL() const;
// Returns the PAC URL configured in DHCP for the given |adapter_name|, or
// the empty string if none is configured.
// This function executes synchronously due to limitations of the Windows
// DHCP client API.
static std::string GetPacURLFromDhcp(const std::string& adapter_name);
// Sanitizes a string returned via the DHCP API.
static std::string SanitizeDhcpApiString(const char* data,
size_t count_bytes);
// This is the state machine for fetching from a given adapter.
// The state machine goes from START->WAIT_DHCP when it starts
// a worker thread to fetch the PAC URL from DHCP.
// In state WAIT_DHCP, if the DHCP query finishes and has no URL, it
// moves to state FINISH. If there is a URL, it starts a
// PacFileFetcher to fetch it and moves to state WAIT_URL.
// It goes from WAIT_URL->FINISH when the PacFileFetcher completes.
// In state FINISH, completion is indicated to the outer class, with
// the results of the fetch if a PAC script was successfully fetched.
// In state WAIT_DHCP, our timeout occurring can push us to FINISH.
// In any state except FINISH, a call to Cancel() will move to state
// CANCEL and cause all outstanding work to be cancelled or its
// results ignored when available.
enum State {
State state() const;
// This inner class encapsulates work done on a worker pool thread.
// By using a separate object, we can keep the main object completely
// thread safe and let it be non-refcounted.
: public base::RefCountedThreadSafe<DhcpQuery> {
// This method should run on a worker pool thread, via PostTaskAndReply.
// After it has run, the |url()| method on this object will return the
// URL retrieved.
void GetPacURLForAdapter(const std::string& adapter_name);
// Returns the URL retrieved for the given adapter, once the task has run.
const std::string& url() const;
// Virtual method introduced to allow unit testing.
virtual std::string ImplGetPacURLFromDhcp(const std::string& adapter_name);
friend class base::RefCountedThreadSafe<DhcpQuery>;
virtual ~DhcpQuery();
// The URL retrieved for the given adapter.
std::string url_;
// Virtual methods introduced to allow unit testing.
virtual std::unique_ptr<PacFileFetcher> ImplCreateScriptFetcher();
virtual DhcpQuery* ImplCreateDhcpQuery();
virtual base::TimeDelta ImplGetTimeout() const;
// Event/state transition handlers
void OnDhcpQueryDone(scoped_refptr<DhcpQuery> dhcp_query,
const NetworkTrafficAnnotationTag traffic_annotation);
void OnTimeout();
void OnFetcherDone(int result);
void TransitionToFinish();
// TaskRunner for posting tasks to a worker thread.
scoped_refptr<base::TaskRunner> task_runner_;
// Current state of this state machine.
State state_;
// A network error indicating result of operation.
int result_;
// Empty string or the PAC script downloaded.
base::string16 pac_script_;
// Empty URL or the PAC URL configured in DHCP.
GURL pac_url_;
// Callback to let our client know we're done. Invalid in states
CompletionOnceCallback callback_;
// Fetcher to retrieve PAC files once URL is known.
std::unique_ptr<PacFileFetcher> script_fetcher_;
// Implements a timeout on the call to the Win32 DHCP API.
base::OneShotTimer wait_timer_;
URLRequestContext* const url_request_context_;
} // namespace net