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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.
#ifndef EXTENSIONS_BROWSER_EXTENSION_THROTTLE_MANAGER_H_
#define EXTENSIONS_BROWSER_EXTENSION_THROTTLE_MANAGER_H_
#include <map>
#include <memory>
#include <string>
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "base/threading/platform_thread.h"
#include "extensions/browser/extension_throttle_entry.h"
#include "net/base/backoff_entry.h"
#include "net/base/net_export.h"
#include "net/base/network_change_notifier.h"
#include "url/gurl.h"
namespace content {
class ResourceThrottle;
}
namespace net {
class NetLog;
class NetLogWithSource;
}
namespace extensions {
// Class that registers URL request throttler entries for URLs being accessed
// in order to supervise traffic. URL requests for HTTP contents should
// register their URLs in this manager on each request.
//
// ExtensionThrottleManager maintains a map of URL IDs to URL request
// throttler entries. It creates URL request throttler entries when new URLs
// are registered, and does garbage collection from time to time in order to
// clean out outdated entries. URL ID consists of lowercased scheme, host, port
// and path. All URLs converted to the same ID will share the same entry.
class ExtensionThrottleManager
: public net::NetworkChangeNotifier::IPAddressObserver,
public net::NetworkChangeNotifier::ConnectionTypeObserver {
public:
ExtensionThrottleManager();
~ExtensionThrottleManager() override;
// Creates a content::ResourceThrottle for |request| to prevent extensions
// from requesting a URL too often, if such a throttle is needed.
std::unique_ptr<content::ResourceThrottle> MaybeCreateThrottle(
const net::URLRequest* request);
// TODO(xunjieli): Remove this method and replace with
// ShouldRejectRequest(request) and UpdateWithResponse(request, status_code),
// which will also allow ExtensionThrottleEntry to no longer be reference
// counted, and ExtensionThrottleEntryInterface to be removed.
// Must be called for every request, returns the URL request throttler entry
// associated with the URL. The caller must inform this entry of some events.
// Please refer to extension_throttle_entry_interface.h for further
// informations.
scoped_refptr<ExtensionThrottleEntryInterface> RegisterRequestUrl(
const GURL& url);
void SetBackoffPolicyForTests(
std::unique_ptr<net::BackoffEntry::Policy> policy);
// Registers a new entry in this service and overrides the existing entry (if
// any) for the URL. The service will hold a reference to the entry.
// It is only used by unit tests.
void OverrideEntryForTests(const GURL& url, ExtensionThrottleEntry* entry);
// Explicitly erases an entry.
// This is useful to remove those entries which have got infinite lifetime and
// thus won't be garbage collected.
// It is only used by unit tests.
void EraseEntryForTests(const GURL& url);
// Sets whether to ignore net::LOAD_MAYBE_USER_GESTURE of the request for
// testing. Otherwise, requests will not be throttled when they may have been
// throttled in response to a recent user gesture, though they're still
// counted for the purpose of throttling other requests.
void SetIgnoreUserGestureLoadFlagForTests(
bool ignore_user_gesture_load_flag_for_tests);
// Turns threading model verification on or off. Any code that correctly
// uses the network stack should preferably call this function to enable
// verification of correct adherence to the network stack threading model.
void set_enable_thread_checks(bool enable);
bool enable_thread_checks() const;
// Whether throttling is enabled or not.
void set_enforce_throttling(bool enforce);
bool enforce_throttling();
// Sets the net::NetLog instance to use.
void set_net_log(net::NetLog* net_log);
net::NetLog* net_log() const;
// IPAddressObserver interface.
void OnIPAddressChanged() override;
// ConnectionTypeObserver interface.
void OnConnectionTypeChanged(
net::NetworkChangeNotifier::ConnectionType type) override;
// Method that allows us to transform a URL into an ID that can be used in our
// map. Resulting IDs will be lowercase and consist of the scheme, host, port
// and path (without query string, fragment, etc.).
// If the URL is invalid, the invalid spec will be returned, without any
// transformation.
std::string GetIdFromUrl(const GURL& url) const;
// Method that ensures the map gets cleaned from time to time. The period at
// which garbage collecting happens is adjustable with the
// kRequestBetweenCollecting constant.
void GarbageCollectEntriesIfNecessary();
// Method that does the actual work of garbage collecting.
void GarbageCollectEntries();
// When we switch from online to offline or change IP addresses, we
// clear all back-off history. This is a precaution in case the change in
// online state now lets us communicate without error with servers that
// we were previously getting 500 or 503 responses from (perhaps the
// responses are from a badly-written proxy that should have returned a
// 502 or 504 because it's upstream connection was down or it had no route
// to the server).
void OnNetworkChange();
// Used by tests.
int GetNumberOfEntriesForTests() const { return url_entries_.size(); }
private:
// From each URL we generate an ID composed of the scheme, host, port and path
// that allows us to uniquely map an entry to it.
typedef std::map<std::string, scoped_refptr<ExtensionThrottleEntry>>
UrlEntryMap;
// Maximum number of entries that we are willing to collect in our map.
static const unsigned int kMaximumNumberOfEntries;
// Number of requests that will be made between garbage collection.
static const unsigned int kRequestsBetweenCollecting;
// Map that contains a list of URL ID and their matching
// ExtensionThrottleEntry.
UrlEntryMap url_entries_;
// This keeps track of how many requests have been made. Used with
// GarbageCollectEntries.
unsigned int requests_since_last_gc_;
// Valid after construction.
GURL::Replacements url_id_replacements_;
// Certain tests do not obey the net component's threading policy, so we
// keep track of whether we're being used by tests, and turn off certain
// checks.
//
// TODO(joi): See if we can fix the offending unit tests and remove this
// workaround.
bool enable_thread_checks_;
// Initially false, switches to true once we have logged because of back-off
// being disabled for localhost.
bool logged_for_localhost_disabled_;
// net::NetLog to use, if configured.
net::NetLogWithSource net_log_;
// Valid once we've registered for network notifications.
base::PlatformThreadId registered_from_thread_;
bool ignore_user_gesture_load_flag_for_tests_;
// This is NULL when it is not set for tests.
std::unique_ptr<net::BackoffEntry::Policy> backoff_policy_for_tests_;
SEQUENCE_CHECKER(sequence_checker_);
DISALLOW_COPY_AND_ASSIGN(ExtensionThrottleManager);
};
} // namespace extensions
#endif // EXTENSIONS_BROWSER_EXTENSION_THROTTLE_MANAGER_H_