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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/time/time.h"
#include "net/base/request_priority.h"
#include "net/dns/dns_config.h"
#include "net/dns/record_rdata.h"
#include "url/gurl.h"
namespace net {
class DnsResponse;
class DnsSession;
class NetLogWithSource;
class ResolveContext;
// 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:
virtual ~DnsTransaction() {}
// 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() = 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() {}
// Starts the probes. Should only be called once and not after destruction of
// the DnsTransactionFactory.
virtual void Start() = 0;
// Restarts (or initially starts if not yet started) the probes for a network
// change. May be called multiple times, but should not be called after
// destruction of the DnsTransactionFactory.
virtual void RestartForNetworkChange() = 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:
// Called with the response or NULL if no matching response was received.
// Note that the |GetDottedName()| of the response may be different than the
// original |hostname| as a result of suffix search.
typedef base::OnceCallback<void(DnsTransaction* transaction,
int neterror,
const DnsResponse* response)>
CallbackType;
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 transaction will run |callback| upon asynchronous completion.
// 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.
virtual std::unique_ptr<DnsTransaction> CreateTransaction(
const std::string& hostname,
uint16_t qtype,
CallbackType callback,
const NetLogWithSource& net_log,
bool secure,
DnsConfig::SecureDnsMode secure_dns_mode,
ResolveContext* resolve_context) WARN_UNUSED_RESULT = 0;
// Creates a runner to run the DoH probe sequence for all configured DoH
// resolvers.
virtual std::unique_ptr<DnsProbeRunner> CreateDohProbeRunner(
ResolveContext* resolve_context) WARN_UNUSED_RESULT = 0;
// The given EDNS0 option will be included in all DNS queries performed by
// transactions from this factory.
virtual void AddEDNSOption(const OptRecordRdata::Opt& opt) = 0;
// Returns the default SecureDnsMode in the config.
virtual DnsConfig::SecureDnsMode GetSecureDnsModeForTest() = 0;
// Creates a DnsTransactionFactory which creates DnsTransactionImpl using the
// |session|.
static std::unique_ptr<DnsTransactionFactory> CreateFactory(
DnsSession* session) WARN_UNUSED_RESULT;
base::WeakPtrFactory<DnsTransactionFactory> weak_factory_{this};
};
} // namespace net
#endif // NET_DNS_DNS_TRANSACTION_H_