src/connectivity/bluetooth/core/bt-host/sm/sc_stage_1_passkey.h

// Copyright 2020 The Fuchsia 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 SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_SM_SC_STAGE_1_PASSKEY_H_
#define SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_SM_SC_STAGE_1_PASSKEY_H_

#include <lib/fit/function.h>

#include <cstdint>

#include "src/connectivity/bluetooth/core/bt-host/common/byte_buffer.h"
#include "src/connectivity/bluetooth/core/bt-host/common/uint128.h"
#include "src/connectivity/bluetooth/core/bt-host/sm/pairing_channel.h"
#include "src/connectivity/bluetooth/core/bt-host/sm/pairing_phase.h"
#include "src/connectivity/bluetooth/core/bt-host/sm/sc_stage_1.h"
#include "src/connectivity/bluetooth/core/bt-host/sm/smp.h"
#include "src/lib/fxl/memory/weak_ptr.h"

namespace bt::sm {
// ScStage1Passkey encapsulates Stage 1 of LE Secure Connections Pairing Phase 2, which takes care
// of authentication using the Passkey Entry method as in V5.0 Vol. 3 Part H 2.3.5.6.3.
//
// This class is not thread safe and is meant to be accessed on the thread it was created on. All
// callbacks will be run by the default dispatcher of a ScStage1Passkey's creation thread.
class ScStage1Passkey final : public ScStage1 {
 public:
  ScStage1Passkey(fxl::WeakPtr<PairingPhase::Listener> listener, Role role, UInt256 local_pub_key_x,
                  UInt256 peer_pub_key_x, PairingMethod method,
                  fxl::WeakPtr<PairingChannel> sm_chan, Stage1CompleteCallback on_complete);
  void Run() override;
  void OnPairingConfirm(PairingConfirmValue confirm) override;
  void OnPairingRandom(PairingRandomValue rand) override;

 private:
  // For SC passkey entry, each bit of the passkey is exchanged and confirmed one-by-one. Calling
  // this function clears variables from the previous exchange (if necessary) and starts the next.
  void StartBitExchange();

  // Functions that handle sending/receiving SMP messages in the exchange of a bit of the passkey.
  void SendPairingConfirm();
  void SendPairingRandom();

  // Called after SMP messages have been exchanged & verified for a given bit of the passkey. Ends
  // stage 1 after all bits are exchanged, or calls StartBitExchange if there are still more bits.
  void FinishBitExchange();

  fxl::WeakPtr<PairingPhase::Listener> listener_;
  Role role_;
  UInt256 local_public_key_x_;
  UInt256 peer_public_key_x_;
  PairingMethod method_;

  // This member is set when the PairingPhase::Listener request for the Passkey completes.
  std::optional<uint32_t> passkey_;
  size_t passkey_bit_location_;

  PairingConfirmValue local_confirm_;
  bool sent_local_confirm_;
  // The presence of |peer_confirm_| signals if we've received the peer's Pairing Random message.
  std::optional<PairingConfirmValue> peer_confirm_;

  PairingRandomValue local_rand_;
  bool sent_local_rand_;
  // The presence of |peer_rand_| signals if we've received the peer's Pairing Random message.
  std::optional<PairingRandomValue> peer_rand_;

  fxl::WeakPtr<PairingChannel> sm_chan_;
  Stage1CompleteCallback on_complete_;
  fxl::WeakPtrFactory<ScStage1Passkey> weak_ptr_factory_;
};
}  // namespace bt::sm

#endif  // SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_SM_SC_STAGE_1_PASSKEY_H_