| // Copyright 2013 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 REMOTING_PROTOCOL_PAIRING_AUTHENTICATOR_BASE_H_ |
| #define REMOTING_PROTOCOL_PAIRING_AUTHENTICATOR_BASE_H_ |
| |
| #include "base/memory/weak_ptr.h" |
| #include "remoting/protocol/authenticator.h" |
| #include "third_party/libjingle/source/talk/xmllite/xmlelement.h" |
| |
| namespace remoting { |
| namespace protocol { |
| |
| // The pairing authenticator builds on top of V2Authenticator to add |
| // support for PIN-less authentication via device pairing: |
| // |
| // * If a client device is already paired, it includes in the initial |
| // authentication message a Client Id and the first SPAKE message |
| // using the Paired Secret and HMAC_SHA256. |
| // * If the host recognizes the Client Id, it looks up the corresponding |
| // Paired Secret and continue the SPAKE exchange. |
| // * If it does not recognize the Client Id, it initiates a SPAKE exchange |
| // with HMAC_SHA256 using the PIN as the shared secret. The initial |
| // message of this exchange includes an an error message, which |
| // informs the client that the PIN-less connection failed and causes |
| // it to prompt the user for a PIN to use for authentication |
| // instead. |
| // * If, at any point, the SPAKE exchange fails with the Paired Secret, |
| // the endpoint that detects the failure initiates a new SPAKE exchange |
| // using the PIN, and includes an error message to instruct the peer |
| // to do likewise. |
| // |
| // If a client device is not already paired, but supports pairing, then |
| // the V2Authenticator is used instead of this class. Only the method name |
| // differs, which the client uses to determine that pairing should be offered |
| // to the user (see NegotiatingHostAuthenticator::CreateAuthenticator and |
| // NegotiatingClientAuthenticator::CreateAuthenticatorForCurrentMethod). |
| class PairingAuthenticatorBase : public Authenticator { |
| public: |
| PairingAuthenticatorBase(); |
| virtual ~PairingAuthenticatorBase(); |
| |
| // Authenticator interface. |
| virtual State state() const OVERRIDE; |
| virtual RejectionReason rejection_reason() const OVERRIDE; |
| virtual void ProcessMessage(const buzz::XmlElement* message, |
| const base::Closure& resume_callback) OVERRIDE; |
| virtual scoped_ptr<buzz::XmlElement> GetNextMessage() OVERRIDE; |
| virtual scoped_ptr<ChannelAuthenticator> |
| CreateChannelAuthenticator() const OVERRIDE; |
| |
| protected: |
| typedef base::Callback<void(scoped_ptr<Authenticator> authenticator)> |
| SetAuthenticatorCallback; |
| |
| static const buzz::StaticQName kPairingInfoTag; |
| static const buzz::StaticQName kClientIdAttribute; |
| |
| // Create a V2 authenticator in the specified state, prompting the user for |
| // the PIN first if necessary. |
| virtual void CreateV2AuthenticatorWithPIN( |
| State initial_state, |
| const SetAuthenticatorCallback& callback) = 0; |
| |
| // Amend an authenticator message, for example to add client- or host-specific |
| // elements to it. |
| virtual void AddPairingElements(buzz::XmlElement* message) = 0; |
| |
| // A non-fatal error message that derived classes should set in order to |
| // cause the peer to be notified that pairing has failed and that it should |
| // fall back on PIN authentication. This string need not be human-readable, |
| // nor is it currently used other than being logged. |
| std::string error_message_; |
| |
| // The underlying V2 authenticator, created with either the PIN or the |
| // Paired Secret by the derived class. |
| scoped_ptr<Authenticator> v2_authenticator_; |
| |
| // Derived classes must set this to True if the underlying authenticator is |
| // using the Paired Secret. |
| bool using_paired_secret_; |
| |
| private: |
| // Helper methods for ProcessMessage and GetNextMessage |
| void MaybeAddErrorMessage(buzz::XmlElement* message); |
| bool HasErrorMessage(const buzz::XmlElement* message) const; |
| void CheckForFailedSpakeExchange(const base::Closure& resume_callback); |
| void SetAuthenticatorAndProcessMessage( |
| const buzz::XmlElement* message, |
| const base::Closure& resume_callback, |
| scoped_ptr<Authenticator> authenticator); |
| |
| // Set to true if a PIN-based authenticator has been requested but has not |
| // yet been set. |
| bool waiting_for_authenticator_; |
| |
| base::WeakPtrFactory<PairingAuthenticatorBase> weak_factory_; |
| |
| DISALLOW_COPY_AND_ASSIGN(PairingAuthenticatorBase); |
| }; |
| |
| } // namespace protocol |
| } // namespace remoting |
| |
| #endif // REMOTING_PROTOCOL_PAIRING_AUTHENTICATOR_H_ |