| // 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_DNS_DNS_SESSION_H_ |
| #define NET_DNS_DNS_SESSION_H_ |
| |
| #include <stdint.h> |
| |
| #include <memory> |
| #include <vector> |
| |
| #include "base/lazy_instance.h" |
| #include "base/macros.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/metrics/bucket_ranges.h" |
| #include "base/time/time.h" |
| #include "net/base/net_export.h" |
| #include "net/base/network_change_notifier.h" |
| #include "net/base/rand_callback.h" |
| #include "net/dns/dns_config.h" |
| #include "net/dns/dns_socket_pool.h" |
| |
| namespace base { |
| class BucketRanges; |
| } |
| |
| namespace net { |
| |
| class DatagramClientSocket; |
| class NetLog; |
| struct NetLogSource; |
| class StreamSocket; |
| |
| // Number of failures allowed before a DoH server is designated 'unavailable'. |
| // In AUTOMATIC mode, non-probe DoH queries should not be sent to DoH servers |
| // that have reached this limit. |
| // This limit is different from the failure limit that governs insecure async |
| // resolver bypass in several ways: the failures need not be consecutive, |
| // NXDOMAIN responses are never counted as failures, and the outcome of |
| // fallback queries is not taken into account. |
| const int kAutomaticModeFailureLimit = 10; |
| |
| // Session parameters and state shared between DNS transactions. |
| // Ref-counted so that DnsClient::Request can keep working in absence of |
| // DnsClient. A DnsSession must be recreated when DnsConfig changes. |
| class NET_EXPORT_PRIVATE DnsSession : public base::RefCounted<DnsSession> { |
| public: |
| typedef base::Callback<int()> RandCallback; |
| |
| class NET_EXPORT_PRIVATE SocketLease { |
| public: |
| SocketLease(scoped_refptr<DnsSession> session, |
| unsigned server_index, |
| std::unique_ptr<DatagramClientSocket> socket); |
| ~SocketLease(); |
| |
| unsigned server_index() const { return server_index_; } |
| |
| DatagramClientSocket* socket() { return socket_.get(); } |
| |
| private: |
| scoped_refptr<DnsSession> session_; |
| unsigned server_index_; |
| std::unique_ptr<DatagramClientSocket> socket_; |
| |
| DISALLOW_COPY_AND_ASSIGN(SocketLease); |
| }; |
| |
| DnsSession(const DnsConfig& config, |
| std::unique_ptr<DnsSocketPool> socket_pool, |
| const RandIntCallback& rand_int_callback, |
| NetLog* net_log); |
| |
| const DnsConfig& config() const { return config_; } |
| NetLog* net_log() const { return net_log_; } |
| |
| void UpdateTimeouts(NetworkChangeNotifier::ConnectionType type); |
| void InitializeServerStats(); |
| |
| // Return the next random query ID. |
| uint16_t NextQueryId() const; |
| |
| // Return the index of the first configured server to use on first attempt. |
| unsigned NextFirstServerIndex(); |
| |
| // Start with |server_index| and find the index of the next known |
| // good non-dns-over-https server to use on this attempt. Returns |
| // |server_index| if this server is below the failure limit, or if there are |
| // no other servers below the failure limit or with an older last failure. |
| unsigned NextGoodServerIndex(unsigned server_index); |
| |
| // Similar to |NextGoodServerIndex| except for DoH servers. If no DoH server |
| // is under the failure limit in AUTOMATIC mode, returns -1. |
| int NextGoodDohServerIndex(unsigned doh_server_index, |
| DnsConfig::SecureDnsMode secure_dns_mode); |
| |
| // Returns whether there is a DoH server that has a successful probe state. |
| bool HasAvailableDohServer(); |
| |
| // Returns the number of DoH servers with successful probe states. |
| unsigned NumAvailableDohServers(); |
| |
| // Record that server failed to respond (due to SRV_FAIL or timeout). If |
| // |is_doh_server| and the number of failures has surpassed a threshold, |
| // sets the DoH probe state to unavailable. |
| void RecordServerFailure(unsigned server_index, bool is_doh_server); |
| |
| // Record that server responded successfully. |
| void RecordServerSuccess(unsigned server_index, bool is_doh_server); |
| |
| // Record the latest DoH probe state. |
| void SetProbeSuccess(unsigned doh_server_index, bool success); |
| |
| // Record how long it took to receive a response from the server. |
| void RecordRTT(unsigned server_index, |
| bool is_doh_server, |
| base::TimeDelta rtt, |
| int rv); |
| |
| // Return the timeout for the next query. |attempt| counts from 0 and is used |
| // for exponential backoff. |
| base::TimeDelta NextTimeout(unsigned server_index, int attempt); |
| |
| // Return the timeout for the next DoH query. |
| base::TimeDelta NextDohTimeout(unsigned doh_server_index); |
| |
| // Allocate a socket, already connected to the server address. |
| // When the SocketLease is destroyed, the socket will be freed. |
| std::unique_ptr<SocketLease> AllocateSocket(unsigned server_index, |
| const NetLogSource& source); |
| |
| // Creates a StreamSocket from the factory for a transaction over TCP. These |
| // sockets are not pooled. |
| std::unique_ptr<StreamSocket> CreateTCPSocket(unsigned server_index, |
| const NetLogSource& source); |
| |
| private: |
| friend class base::RefCounted<DnsSession>; |
| struct ServerStats; |
| ~DnsSession(); |
| |
| // Release a socket. |
| void FreeSocket(unsigned server_index, |
| std::unique_ptr<DatagramClientSocket> socket); |
| |
| // Returns the ServerStats for the designated server. Returns nullptr if no |
| // ServerStats found. |
| ServerStats* GetServerStats(unsigned server_index, bool is_doh_server); |
| |
| // Return the timeout for the next query. |
| base::TimeDelta NextTimeoutHelper(ServerStats* server_stats, int attempt); |
| |
| // Record the time to perform a query. |
| void RecordRTTForHistogram(unsigned server_index, |
| bool is_doh_server, |
| base::TimeDelta rtt, |
| int rv); |
| |
| const DnsConfig config_; |
| std::unique_ptr<DnsSocketPool> socket_pool_; |
| RandCallback rand_callback_; |
| NetLog* net_log_; |
| |
| // Current index into |config_.nameservers| to begin resolution with. |
| int server_index_; |
| |
| base::TimeDelta initial_timeout_; |
| base::TimeDelta max_timeout_; |
| |
| // Track runtime statistics of each insecure DNS server. |
| std::vector<std::unique_ptr<ServerStats>> server_stats_; |
| |
| // Track runtime statistics and availability of each DoH server. |
| std::vector<std::pair<std::unique_ptr<ServerStats>, bool>> doh_server_stats_; |
| |
| // Buckets shared for all |ServerStats::rtt_histogram|. |
| struct RttBuckets : public base::BucketRanges { |
| RttBuckets(); |
| }; |
| static base::LazyInstance<RttBuckets>::Leaky rtt_buckets_; |
| |
| DISALLOW_COPY_AND_ASSIGN(DnsSession); |
| }; |
| |
| } // namespace net |
| |
| #endif // NET_DNS_DNS_SESSION_H_ |