144 lines
5.3 KiB
C++
144 lines
5.3 KiB
C++
// Copyright 2012 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef NET_DNS_DNS_TRANSACTION_H_
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#define NET_DNS_DNS_TRANSACTION_H_
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#include <stdint.h>
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#include <memory>
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#include <string>
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#include "base/functional/callback.h"
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#include "base/memory/weak_ptr.h"
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#include "base/strings/string_piece.h"
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#include "base/time/time.h"
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#include "net/base/request_priority.h"
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#include "net/dns/opt_record_rdata.h"
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#include "net/dns/public/secure_dns_mode.h"
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#include "net/dns/record_rdata.h"
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#include "third_party/abseil-cpp/absl/types/optional.h"
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#include "url/gurl.h"
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namespace net {
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class DnsResponse;
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class DnsSession;
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class NetLogWithSource;
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class ResolveContext;
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// The hostname probed by CreateDohProbeRunner().
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inline constexpr base::StringPiece kDohProbeHostname = "www.gstatic.com";
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// DnsTransaction implements a stub DNS resolver as defined in RFC 1034.
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// The DnsTransaction takes care of retransmissions, name server fallback (or
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// round-robin), suffix search, and simple response validation ("does it match
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// the query") to fight poisoning.
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//
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// Destroying DnsTransaction cancels the underlying network effort.
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class NET_EXPORT_PRIVATE DnsTransaction {
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public:
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// Called with the response or nullptr if no matching response was received.
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// Note that the `GetDottedName()` of the response may be different than the
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// original `hostname` (passed to `DnsTransactionFactory::CreateTransaction()`
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// as a result of suffix search.
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using ResponseCallback =
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base::OnceCallback<void(int neterror, const DnsResponse* response)>;
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virtual ~DnsTransaction() = default;
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// Returns the original |hostname|.
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virtual const std::string& GetHostname() const = 0;
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// Returns the |qtype|.
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virtual uint16_t GetType() const = 0;
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// Starts the transaction. Always completes asynchronously.
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virtual void Start(ResponseCallback callback) = 0;
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virtual void SetRequestPriority(RequestPriority priority) = 0;
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};
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// Startable/Cancellable object to represent a DNS probe sequence.
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class DnsProbeRunner {
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public:
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// Destruction cancels the probes.
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virtual ~DnsProbeRunner() = default;
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// Starts all applicable probes that are not already running. May be called
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// multiple times, but should not be called after destruction of the
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// DnsTransactionFactory.
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//
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// Set |network_change| to indicate if this start or restart was triggered by
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// a network connection change. Only used for logging and metrics.
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virtual void Start(bool network_change) = 0;
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// Gets the delay until the next scheduled probe to the specified DoH server.
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// Returns base::TimeDelta() if no probe scheduled.
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virtual base::TimeDelta GetDelayUntilNextProbeForTest(
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size_t doh_server_index) const = 0;
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};
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// Creates DnsTransaction which performs asynchronous DNS search.
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// It does NOT perform caching, aggregation or prioritization of transactions.
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//
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// Destroying the factory does NOT affect any already created DnsTransactions.
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//
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// DnsProbeRunners, however, will safely abort themselves on destruction of
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// their creating factory, and they should only be started or restarted while
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// the factory is still alive.
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class NET_EXPORT_PRIVATE DnsTransactionFactory {
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public:
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DnsTransactionFactory();
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virtual ~DnsTransactionFactory();
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// Creates DnsTransaction for the given |hostname| and |qtype| (assuming
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// QCLASS is IN). |hostname| should be in the dotted form. A dot at the end
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// implies the domain name is fully-qualified and will be exempt from suffix
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// search. |hostname| should not be an IP literal.
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//
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// The |net_log| is used as the parent log.
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//
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// |secure| specifies whether DNS lookups should be performed using DNS-over-
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// HTTPS (DoH) or using plaintext DNS.
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//
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// When |fast_timeout| is true, the transaction will timeout quickly after
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// making its DNS attempts, without necessarily waiting long enough to allow
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// slower-than-average requests to complete. Intended as an optimization for
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// cases where the caller has reasonable fallback options to the transaction
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// and it would be beneficial to move on to those options sooner on signals
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// that the transaction is potentially slow or problematic.
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[[nodiscard]] virtual std::unique_ptr<DnsTransaction> CreateTransaction(
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std::string hostname,
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uint16_t qtype,
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const NetLogWithSource& net_log,
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bool secure,
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SecureDnsMode secure_dns_mode,
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ResolveContext* resolve_context,
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bool fast_timeout) = 0;
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// Creates a runner to run the DoH probe sequence for all configured DoH
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// resolvers.
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[[nodiscard]] virtual std::unique_ptr<DnsProbeRunner> CreateDohProbeRunner(
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ResolveContext* resolve_context) = 0;
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// The given EDNS0 option will be included in all DNS queries performed by
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// transactions from this factory.
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virtual void AddEDNSOption(std::unique_ptr<OptRecordRdata::Opt> opt) = 0;
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// Returns the default SecureDnsMode in the config.
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virtual SecureDnsMode GetSecureDnsModeForTest() = 0;
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// Creates a DnsTransactionFactory which creates DnsTransactionImpl using the
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// |session|.
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[[nodiscard]] static std::unique_ptr<DnsTransactionFactory> CreateFactory(
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DnsSession* session);
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base::WeakPtrFactory<DnsTransactionFactory> weak_factory_{this};
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};
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} // namespace net
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#endif // NET_DNS_DNS_TRANSACTION_H_
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