net/socket/transport_connect_job.h

// Copyright 2018 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_SOCKET_TRANSPORT_CONNECT_JOB_H_
#define NET_SOCKET_TRANSPORT_CONNECT_JOB_H_

#include <memory>
#include <set>
#include <string>
#include <vector>

#include "base/callback.h"
#include "base/containers/flat_set.h"
#include "base/containers/span.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "net/base/host_port_pair.h"
#include "net/base/net_export.h"
#include "net/base/network_isolation_key.h"
#include "net/dns/host_resolver.h"
#include "net/dns/host_resolver_results.h"
#include "net/dns/public/resolve_error_info.h"
#include "net/dns/public/secure_dns_policy.h"
#include "net/socket/connect_job.h"
#include "net/socket/connection_attempts.h"
#include "net/socket/socket_tag.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
#include "third_party/abseil-cpp/absl/types/variant.h"
#include "url/scheme_host_port.h"

namespace net {

class NetLogWithSource;
class SocketTag;

class NET_EXPORT_PRIVATE TransportSocketParams
    : public base::RefCounted<TransportSocketParams> {
 public:
  // Representation of the destination endpoint of the transport
  // socket/connection. Unlike ConnectJobFactory::Endpoint, this does not have a
  // `using_ssl` field for schemeless endpoints because that has no meaning for
  // transport parameters.
  using Endpoint = absl::variant<url::SchemeHostPort, HostPortPair>;

  // |host_resolution_callback| will be invoked after the the hostname is
  // resolved. |network_isolation_key| is passed to the HostResolver to prevent
  // cross-NIK leaks. If |host_resolution_callback| does not return OK, then the
  // connection will be aborted with that value. |supported_alpns| specifies
  // ALPN protocols for selecting HTTPS/SVCB records. If empty, addresses from
  // HTTPS/SVCB records will be ignored and only A/AAAA will be used.
  TransportSocketParams(Endpoint destination,
                        NetworkIsolationKey network_isolation_key,
                        SecureDnsPolicy secure_dns_policy,
                        OnHostResolutionCallback host_resolution_callback,
                        base::flat_set<std::string> supported_alpns);

  TransportSocketParams(const TransportSocketParams&) = delete;
  TransportSocketParams& operator=(const TransportSocketParams&) = delete;

  const Endpoint& destination() const { return destination_; }
  const NetworkIsolationKey& network_isolation_key() const {
    return network_isolation_key_;
  }
  SecureDnsPolicy secure_dns_policy() const { return secure_dns_policy_; }
  const OnHostResolutionCallback& host_resolution_callback() const {
    return host_resolution_callback_;
  }
  const base::flat_set<std::string>& supported_alpns() const {
    return supported_alpns_;
  }

 private:
  friend class base::RefCounted<TransportSocketParams>;
  ~TransportSocketParams();

  const Endpoint destination_;
  const NetworkIsolationKey network_isolation_key_;
  const SecureDnsPolicy secure_dns_policy_;
  const OnHostResolutionCallback host_resolution_callback_;
  const base::flat_set<std::string> supported_alpns_;
};

// TransportConnectJob handles the host resolution necessary for socket creation
// and the transport (likely TCP) connect. TransportConnectJob also has fallback
// logic for IPv6 connect() timeouts (which may happen due to networks / routers
// with broken IPv6 support). Those timeouts take 20s, so rather than make the
// user wait 20s for the timeout to fire, we use a fallback timer
// (kIPv6FallbackTimerInMs) and start a connect() to a IPv4 address if the timer
// fires. Then we race the IPv4 connect() against the IPv6 connect() (which has
// a headstart) and return the one that completes first to the socket pool.
class NET_EXPORT_PRIVATE TransportConnectJob : public ConnectJob {
 public:
  class NET_EXPORT_PRIVATE Factory {
   public:
    Factory() = default;
    virtual ~Factory() = default;

    virtual std::unique_ptr<TransportConnectJob> Create(
        RequestPriority priority,
        const SocketTag& socket_tag,
        const CommonConnectJobParams* common_connect_job_params,
        const scoped_refptr<TransportSocketParams>& params,
        Delegate* delegate,
        const NetLogWithSource* net_log);
  };

  // TransportConnectJobs will time out after this many seconds.  Note this is
  // the total time, including both host resolution and TCP connect() times.
  static const int kTimeoutInSeconds;

  // In cases where both IPv6 and IPv4 addresses were returned from DNS,
  // TransportConnectJobs will start a second connection attempt to just the
  // IPv4 addresses after this many milliseconds. (This is "Happy Eyeballs".)
  static const int kIPv6FallbackTimerInMs;

  // Creates a TransportConnectJob or WebSocketTransportConnectJob, depending on
  // whether or not |common_connect_job_params.web_socket_endpoint_lock_manager|
  // is nullptr.
  // TODO(mmenke): Merge those two ConnectJob classes, and remove this method.
  static std::unique_ptr<ConnectJob> CreateTransportConnectJob(
      scoped_refptr<TransportSocketParams> transport_client_params,
      RequestPriority priority,
      const SocketTag& socket_tag,
      const CommonConnectJobParams* common_connect_job_params,
      ConnectJob::Delegate* delegate,
      const NetLogWithSource* net_log);

  struct NET_EXPORT_PRIVATE EndpointResultOverride {
    EndpointResultOverride(HostResolverEndpointResult result,
                           std::set<std::string> dns_aliases);
    EndpointResultOverride(EndpointResultOverride&&);
    EndpointResultOverride(const EndpointResultOverride&);
    ~EndpointResultOverride();
    EndpointResultOverride& operator=(EndpointResultOverride&&);
    EndpointResultOverride& operator=(const EndpointResultOverride&);

    HostResolverEndpointResult result;
    std::set<std::string> dns_aliases;
  };

  TransportConnectJob(RequestPriority priority,
                      const SocketTag& socket_tag,
                      const CommonConnectJobParams* common_connect_job_params,
                      const scoped_refptr<TransportSocketParams>& params,
                      Delegate* delegate,
                      const NetLogWithSource* net_log,
                      absl::optional<EndpointResultOverride>
                          endpoint_result_override = absl::nullopt);

  TransportConnectJob(const TransportConnectJob&) = delete;
  TransportConnectJob& operator=(const TransportConnectJob&) = delete;

  ~TransportConnectJob() override;

  // ConnectJob methods.
  LoadState GetLoadState() const override;
  bool HasEstablishedConnection() const override;
  ConnectionAttempts GetConnectionAttempts() const override;
  ResolveErrorInfo GetResolveErrorInfo() const override;
  absl::optional<HostResolverEndpointResult> GetHostResolverEndpointResult()
      const override;

  // Skips DNS resolution and instead connects to `endpoint_result`, reporting
  // `dns_aliases` as the list of DNS aliases. Must be called before `Connect`.
  void SetDnsResultOverride(const HostResolverEndpointResult& endpoint_result,
                            const std::set<std::string>& dns_aliases);

  // Rolls |addrlist| forward until the first IPv4 address, if any.
  // WARNING: this method should only be used to implement the prefer-IPv4 hack.
  static void MakeAddressListStartWithIPv4(AddressList* addrlist);

  // Record the histograms Net.DNS_Resolution_And_TCP_Connection_Latency2 and
  // Net.TCP_Connection_Latency and return the connect duration.
  static void HistogramDuration(
      const LoadTimingInfo::ConnectTiming& connect_timing);

  static base::TimeDelta ConnectionTimeout();

 private:
  enum State {
    STATE_RESOLVE_HOST,
    STATE_RESOLVE_HOST_COMPLETE,
    STATE_RESOLVE_HOST_CALLBACK_COMPLETE,
    STATE_TRANSPORT_CONNECT,
    STATE_TRANSPORT_CONNECT_COMPLETE,
    STATE_FALLBACK_CONNECT_COMPLETE,
    STATE_NONE,
  };

  void OnIOComplete(int result);
  int DoLoop(int result);

  int DoResolveHost();
  int DoResolveHostComplete(int result);
  int DoResolveHostCallbackComplete();
  int DoTransportConnect();
  int DoTransportConnectComplete(bool is_fallback, int result);

  // Not part of the state machine.
  void OnIPv6FallbackTimerComplete();
  void OnIPv6FallbackConnectComplete(int rv);

  // Begins the host resolution and the TCP connect.  Returns OK on success
  // and ERR_IO_PENDING if it cannot immediately service the request.
  // Otherwise, it returns a net error code.
  int ConnectInternal() override;

  // If host resolution is currently underway, change the priority of the host
  // resolver request.
  void ChangePriorityInternal(RequestPriority priority) override;

  // Returns whether the client should be SVCB-optional when connecting to
  // `results`.
  bool IsSvcbOptional(
      base::span<const HostResolverEndpointResult> results) const;

  // Returns whether `result` is usable for this connection. If `svcb_optional`
  // is true, the non-HTTPS/SVCB fallback is allowed.
  bool IsEndpointResultUsable(const HostResolverEndpointResult& result,
                              bool svcb_optional) const;

  // Returns an `AddressList` containing the IP endpoints for the current route.
  // May only be called if the current route is usable for this connection.
  AddressList GetCurrentAddressList() const;

  // Appends connection attempts from `socket` to `connection_attempts_`. Should
  // be called when discarding a failed socket.
  void SaveConnectionAttempts(const StreamSocket& socket);

  scoped_refptr<TransportSocketParams> params_;
  std::unique_ptr<HostResolver::ResolveHostRequest> request_;
  std::vector<HostResolverEndpointResult> endpoint_results_;
  size_t current_endpoint_result_ = 0;
  std::set<std::string> dns_aliases_;
  bool has_dns_override_ = false;

  State next_state_;

  std::unique_ptr<StreamSocket> transport_socket_;

  std::unique_ptr<StreamSocket> fallback_transport_socket_;
  base::TimeTicks fallback_connect_start_time_;
  base::OneShotTimer fallback_timer_;

  int resolve_result_;
  ResolveErrorInfo resolve_error_info_;

  // Used in the failure case to save connection attempts made on the main and
  // fallback sockets and pass them on in |GetAdditionalErrorState|. (In the
  // success case, connection attempts are passed through the returned socket;
  // attempts are copied from the other socket, if one exists, into it before
  // it is returned.)
  ConnectionAttempts connection_attempts_;

  base::WeakPtrFactory<TransportConnectJob> weak_ptr_factory_{this};
};

}  // namespace net

#endif  // NET_SOCKET_TRANSPORT_CONNECT_JOB_H_