remoting/protocol/pairing_authenticator_base.cc

// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "remoting/protocol/pairing_authenticator_base.h"

#include <utility>

#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/location.h"
#include "base/logging.h"
#include "remoting/base/constants.h"
#include "remoting/protocol/authenticator.h"
#include "remoting/protocol/credentials_type.h"

namespace remoting::protocol {

PairingAuthenticatorBase::PairingAuthenticatorBase() {}
PairingAuthenticatorBase::~PairingAuthenticatorBase() = default;

CredentialsType PairingAuthenticatorBase::credentials_type() const {
  return CredentialsType::PAIRED;
}

const Authenticator& PairingAuthenticatorBase::implementing_authenticator()
    const {
  return *this;
}

Authenticator::State PairingAuthenticatorBase::state() const {
  DCHECK(spake2_authenticator_);
  return spake2_authenticator_->state();
}

bool PairingAuthenticatorBase::started() const {
  if (!spake2_authenticator_) {
    return false;
  }
  return spake2_authenticator_->started();
}

Authenticator::RejectionReason PairingAuthenticatorBase::rejection_reason()
    const {
  if (!spake2_authenticator_) {
    return RejectionReason::INVALID_STATE;
  }
  return spake2_authenticator_->rejection_reason();
}

Authenticator::RejectionDetails PairingAuthenticatorBase::rejection_details()
    const {
  if (spake2_authenticator_ &&
      spake2_authenticator_->state() == State::REJECTED) {
    Authenticator::RejectionDetails spake2_rejection_details =
        spake2_authenticator_->rejection_details();
    if (!spake2_rejection_details.is_null()) {
      return spake2_rejection_details;
    }
  }
  return RejectionDetails(error_message_);
}

void PairingAuthenticatorBase::ProcessMessage(
    const JingleAuthentication& message,
    base::OnceClosure resume_callback) {
  DCHECK_EQ(state(), WAITING_MESSAGE);

  // The client authenticator creates the underlying authenticator in the ctor
  // and the host creates it in response to the first message before deferring
  // to this class to process it. Either way, it should exist here.
  DCHECK(spake2_authenticator_);

  // If pairing failed, and we haven't already done so, try again with the PIN.
  if (using_paired_secret_ && HasErrorMessage(message)) {
    using_paired_secret_ = false;
    spake2_authenticator_.reset();
    CreateSpakeAuthenticatorWithPin(
        WAITING_MESSAGE,
        base::BindOnce(&PairingAuthenticatorBase::ProcessMessage,
                       weak_factory_.GetWeakPtr(), message,
                       std::move(resume_callback)));
    return;
  }

  // Pass the message to the underlying authenticator for processing, but
  // check for a failed SPAKE exchange if we're using the paired secret. In
  // this case the pairing protocol can continue by communicating the error
  // to the peer and retrying with the PIN.
  spake2_authenticator_->ProcessMessage(
      message,
      base::BindOnce(&PairingAuthenticatorBase::CheckForFailedSpakeExchange,
                     weak_factory_.GetWeakPtr(), std::move(resume_callback)));
}

JingleAuthentication PairingAuthenticatorBase::GetNextMessage() {
  DCHECK_EQ(state(), MESSAGE_READY);
  auto self = weak_factory_.GetWeakPtr();
  JingleAuthentication result = spake2_authenticator_->GetNextMessage();
  if (!self) {
    return result;
  }
  MaybeAddErrorMessage(result);
  return result;
}

const std::string& PairingAuthenticatorBase::GetAuthKey() const {
  return spake2_authenticator_->GetAuthKey();
}

const SessionPolicies* PairingAuthenticatorBase::GetSessionPolicies() const {
  return nullptr;
}

void PairingAuthenticatorBase::MaybeAddErrorMessage(
    JingleAuthentication& message) {
  if (!error_message_.empty()) {
    message.pairing_error = error_message_;
    error_message_.clear();
  }
}

bool PairingAuthenticatorBase::HasErrorMessage(
    const JingleAuthentication& message) const {
  if (!message.pairing_error.empty()) {
    LOG(ERROR) << "Pairing failed: " << message.pairing_error;
    return true;
  }
  return false;
}

void PairingAuthenticatorBase::CheckForFailedSpakeExchange(
    base::OnceClosure resume_callback) {
  // If the SPAKE exchange failed due to invalid credentials, and those
  // credentials were the paired secret, then notify the peer that the
  // PIN-less connection failed and retry using the PIN.
  if (spake2_authenticator_->state() == REJECTED &&
      spake2_authenticator_->rejection_reason() ==
          RejectionReason::INVALID_CREDENTIALS &&
      using_paired_secret_) {
    using_paired_secret_ = false;
    error_message_ = "invalid-shared-secret";
    spake2_authenticator_.reset();
    CreateSpakeAuthenticatorWithPin(MESSAGE_READY, std::move(resume_callback));
    return;
  }

  std::move(resume_callback).Run();
}

}  // namespace remoting::protocol