PairingAuthenticator implementation and plumbing.

remoting/protocol/pairing_client_authenticator.h

Index: remoting/protocol/pairing_client_authenticator.h
diff --git a/remoting/protocol/pairing_client_authenticator.h b/remoting/protocol/pairing_client_authenticator.h
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+// 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_CLIENT_AUTHENTICATOR_H_
+#define REMOTING_PROTOCOL_PAIRING_CLIENT_AUTHENTICATOR_H_
+
+#include "base/memory/weak_ptr.h"
+#include "remoting/protocol/authenticator.h"
+
+namespace remoting {
+
+class RsaKeyPair;
+
+namespace protocol {
+
+class Authenticator;
+
+typedef base::Callback<void(const std::string& secret)> SecretFetchedCallback;
+typedef base::Callback<void(
+    const SecretFetchedCallback& secret_fetched_callback)> FetchSecretCallback;
+
+// PairingClientAuthenticator builds on top of V2Authenticator to add
+// support for PIN-less authentication via device pairing. If a client
+// device is already paired, it includes a client id in the initial
+// authentication message. If the host recognizes the id, it looks up
+// the corresponding shared secret to authenticate the client. If it
+// does not recognize the id, it sends an error message to the client,
+// which will prompt the user for a PIN to use for authentication
+// instead. In either case, the V2Authenticator is used for
+// authentication.
+class PairingClientAuthenticator : public Authenticator {
+ public:
+  PairingClientAuthenticator(
+      const std::string& client_id,
+      const std::string& shared_secret,
+      const FetchSecretCallback& fetch_secret_callback,
+      const std::string& authentication_tag);
+  virtual ~PairingClientAuthenticator() {}
+
+  // 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;
+
+ private:
+  void CreateV2AuthenticatorWithSecret(const base::Closure& resume_callback,
+                                       const std::string& secret);
+
+  bool initial_message_sent_;
+  std::string client_id_;
+  const std::string& shared_secret_;
+  FetchSecretCallback fetch_secret_callback_;
+  std::string authentication_tag_;
+  State initial_state_;
+  scoped_ptr<Authenticator> v2_authenticator_;
+  bool pairing_failed_;
+  base::WeakPtrFactory<PairingClientAuthenticator> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PairingClientAuthenticator);
+};
+
+}  // namespace protocol
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_PAIRING_AUTHENTICATOR_H_