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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 NET_DNS_DNS_TRANSACTION_H_
- #define NET_DNS_DNS_TRANSACTION_H_
- #include <stdint.h>
- #include <memory>
- #include <string>
- #include "base/callback.h"
- #include "base/memory/weak_ptr.h"
- #include "base/strings/string_piece.h"
- #include "base/time/time.h"
- #include "net/base/request_priority.h"
- #include "net/dns/opt_record_rdata.h"
- #include "net/dns/public/secure_dns_mode.h"
- #include "net/dns/record_rdata.h"
- #include "third_party/abseil-cpp/absl/types/optional.h"
- #include "url/gurl.h"
- namespace net {
- class DnsResponse;
- class DnsSession;
- class NetLogWithSource;
- class ResolveContext;
- // The hostname probed by CreateDohProbeRunner().
- inline constexpr base::StringPiece kDohProbeHostname = "www.gstatic.com";
- // DnsTransaction implements a stub DNS resolver as defined in RFC 1034.
- // The DnsTransaction takes care of retransmissions, name server fallback (or
- // round-robin), suffix search, and simple response validation ("does it match
- // the query") to fight poisoning.
- //
- // Destroying DnsTransaction cancels the underlying network effort.
- class NET_EXPORT_PRIVATE DnsTransaction {
- public:
- // Called with the response or nullptr if no matching response was received.
- // Note that the `GetDottedName()` of the response may be different than the
- // original `hostname` (passed to `DnsTransactionFactory::CreateTransaction()`
- // as a result of suffix search.
- using ResponseCallback =
- base::OnceCallback<void(int neterror, const DnsResponse* response)>;
- virtual ~DnsTransaction() = default;
- // Returns the original |hostname|.
- virtual const std::string& GetHostname() const = 0;
- // Returns the |qtype|.
- virtual uint16_t GetType() const = 0;
- // Starts the transaction. Always completes asynchronously.
- virtual void Start(ResponseCallback callback) = 0;
- virtual void SetRequestPriority(RequestPriority priority) = 0;
- };
- // Startable/Cancellable object to represent a DNS probe sequence.
- class DnsProbeRunner {
- public:
- // Destruction cancels the probes.
- virtual ~DnsProbeRunner() = default;
- // Starts all applicable probes that are not already running. May be called
- // multiple times, but should not be called after destruction of the
- // DnsTransactionFactory.
- //
- // Set |network_change| to indicate if this start or restart was triggered by
- // a network connection change. Only used for logging and metrics.
- virtual void Start(bool network_change) = 0;
- // Gets the delay until the next scheduled probe to the specified DoH server.
- // Returns base::TimeDelta() if no probe scheduled.
- virtual base::TimeDelta GetDelayUntilNextProbeForTest(
- size_t doh_server_index) const = 0;
- };
- // Creates DnsTransaction which performs asynchronous DNS search.
- // It does NOT perform caching, aggregation or prioritization of transactions.
- //
- // Destroying the factory does NOT affect any already created DnsTransactions.
- //
- // DnsProbeRunners, however, will safely abort themselves on destruction of
- // their creating factory, and they should only be started or restarted while
- // the factory is still alive.
- class NET_EXPORT_PRIVATE DnsTransactionFactory {
- public:
- DnsTransactionFactory();
- virtual ~DnsTransactionFactory();
- // Creates DnsTransaction for the given |hostname| and |qtype| (assuming
- // QCLASS is IN). |hostname| should be in the dotted form. A dot at the end
- // implies the domain name is fully-qualified and will be exempt from suffix
- // search. |hostname| should not be an IP literal.
- //
- // The |net_log| is used as the parent log.
- //
- // |secure| specifies whether DNS lookups should be performed using DNS-over-
- // HTTPS (DoH) or using plaintext DNS.
- //
- // When |fast_timeout| is true, the transaction will timeout quickly after
- // making its DNS attempts, without necessarily waiting long enough to allow
- // slower-than-average requests to complete. Intended as an optimization for
- // cases where the caller has reasonable fallback options to the transaction
- // and it would be beneficial to move on to those options sooner on signals
- // that the transaction is potentially slow or problematic.
- [[nodiscard]] virtual std::unique_ptr<DnsTransaction> CreateTransaction(
- std::string hostname,
- uint16_t qtype,
- const NetLogWithSource& net_log,
- bool secure,
- SecureDnsMode secure_dns_mode,
- ResolveContext* resolve_context,
- bool fast_timeout) = 0;
- // Creates a runner to run the DoH probe sequence for all configured DoH
- // resolvers.
- [[nodiscard]] virtual std::unique_ptr<DnsProbeRunner> CreateDohProbeRunner(
- ResolveContext* resolve_context) = 0;
- // The given EDNS0 option will be included in all DNS queries performed by
- // transactions from this factory.
- virtual void AddEDNSOption(std::unique_ptr<OptRecordRdata::Opt> opt) = 0;
- // Returns the default SecureDnsMode in the config.
- virtual SecureDnsMode GetSecureDnsModeForTest() = 0;
- // Creates a DnsTransactionFactory which creates DnsTransactionImpl using the
- // |session|.
- [[nodiscard]] static std::unique_ptr<DnsTransactionFactory> CreateFactory(
- DnsSession* session);
- base::WeakPtrFactory<DnsTransactionFactory> weak_factory_{this};
- };
- } // namespace net
- #endif // NET_DNS_DNS_TRANSACTION_H_
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