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- // Copyright 2020 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_DNS_DNS_UDP_TRACKER_H_
- #define NET_DNS_DNS_UDP_TRACKER_H_
- #include <stdint.h>
- #include "base/containers/circular_deque.h"
- #include "base/memory/raw_ptr.h"
- #include "base/time/default_tick_clock.h"
- #include "base/time/time.h"
- #include "net/base/net_export.h"
- namespace base {
- class TickClock;
- } // namespace base
- namespace net {
- // Data tracker for DNS UDP and its usage of local ports. Intended to be owned
- // by a DnsSession and thus keep track of the data session-wide. Responsible for
- // related metrics and used to inform behavior based on the stored data.
- //
- // TODO(ericorth@chromium.org): Add methods to access the stored data or
- // conclusions about it.
- class NET_EXPORT_PRIVATE DnsUdpTracker {
- public:
- static constexpr base::TimeDelta kMaxAge = base::Minutes(10);
- static constexpr size_t kMaxRecordedQueries = 256;
- // How recently an ID needs to be recorded in a recent query to be considered
- // "recognized".
- static constexpr base::TimeDelta kMaxRecognizedIdAge = base::Seconds(15);
- // Numbers of ID mismatches required to set the |low_entropy_| flag. Also
- // serves as the max number of mismatches to be recorded, as no more entries
- // are recorded after setting the flag.
- static constexpr size_t kUnrecognizedIdMismatchThreshold = 8;
- static constexpr size_t kRecognizedIdMismatchThreshold = 128;
- // Number of reuses of the same port required to set the |low_entropy_| flag.
- static constexpr int kPortReuseThreshold = 2;
- DnsUdpTracker();
- ~DnsUdpTracker();
- DnsUdpTracker(DnsUdpTracker&&);
- DnsUdpTracker& operator=(DnsUdpTracker&&);
- void RecordQuery(uint16_t port, uint16_t query_id);
- void RecordResponseId(uint16_t query_id, uint16_t response_id);
- void RecordConnectionError(int connection_error);
- // If true, the entropy from random UDP port and DNS ID has been detected to
- // potentially be low, e.g. due to exhaustion of the port pool or mismatches
- // on IDs.
- bool low_entropy() const { return low_entropy_; }
- void set_tick_clock_for_testing(base::TickClock* tick_clock) {
- tick_clock_ = tick_clock;
- }
- private:
- struct QueryData;
- void PurgeOldRecords();
- void SaveQuery(QueryData query);
- void SaveIdMismatch(uint16_t it);
- bool low_entropy_ = false;
- base::circular_deque<QueryData> recent_queries_;
- // Times of recent ID mismatches, separated by whether or not the ID was
- // recognized from recent queries.
- base::circular_deque<base::TimeTicks> recent_unrecognized_id_hits_;
- base::circular_deque<base::TimeTicks> recent_recognized_id_hits_;
- raw_ptr<const base::TickClock> tick_clock_ =
- base::DefaultTickClock::GetInstance();
- };
- } // namespace net
- #endif // NET_DNS_DNS_UDP_TRACKER_H_
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