Added HostKeyPair class, signatures for heartbeat messages.

remoting/host/heartbeat_sender.h

Index: remoting/host/heartbeat_sender.h
diff --git a/remoting/host/heartbeat_sender.h b/remoting/host/heartbeat_sender.h
index 08665c6451145ec07798f66e45a21eb12843fe9a..b8d459f55dd676bb29e7c4d9209f37db687ffb99 100644
--- a/remoting/host/heartbeat_sender.h
+++ b/remoting/host/heartbeat_sender.h
@@ -9,34 +9,80 @@
 
 #include "base/scoped_ptr.h"
 #include "base/ref_counted.h"
+#include "remoting/host/host_key_pair.h"
 #include "remoting/jingle_glue/iq_request.h"
+#include "testing/gtest/include/gtest/gtest_prod.h"
 
 namespace remoting {
 
 class IqRequest;
+class HostKeyPair;
 class JingleClient;
 class MutableHostConfig;
 
-// HeartbeatSender periodically sends hertbeats to the chromoting bot.
-// TODO(sergeyu): Write unittest for this class.
+// HeartbeatSender periodically sends heartbeat stanzas to the Chromoting Bot.
+// Each heartbeat stanza looks as follows:
+//
+// <iq type="set" to="remoting@bot.talk.google.com"
+//     from="user@gmail.com/chromoting123123" id="5" xmlns="jabber:client">
+//   <rem:heartbeat rem:hostid="a1ddb11e-8aef-11df-bccf-18a905b9cb5a"
+//                  xmlns:rem="google:remoting">
+//     <rem:signature rem:time="1279061748">.signature.</rem:signature>
+//   </rem:heartbeat>
+// </iq>
+//
+// The time attribute of the signature is the decimal time when the message
+// was sent in second since the epoch (01/01/1970). The signature is a BASE64
+// encoded SHA-1/RSA signature created with the host's private key. The message
+// being signed is the full Jid concatenated with the time value, separated by
+// space. For example, for the heartbeat stanza above the message that is being
+// signed is "user@gmail.com/chromoting123123 1279061748".
 class HeartbeatSender : public base::RefCountedThreadSafe<HeartbeatSender> {
  public:
   HeartbeatSender();
+  virtual ~HeartbeatSender();
 
-  // Starts heart-beating for |jingle_client|.
-  void Start(MutableHostConfig* config, JingleClient* jingle_client);
+  // Initializes heart-beating for |jingle_client| with the specified
+  // config. Returns false if the config is invalid (e.g. private key
+  // cannot be parsed).
+  bool Init(MutableHostConfig* config, JingleClient* jingle_client);
+
+  // Starts heart-beating. Must be called after init.
+  void Start();
+
+  // Stops heart-beating. Must be called before corresponding JingleClient
+  // is destroyed. This object will not be deleted until Stop() is called,
+  // and it may (and will) crash after JingleClient is destroyed. Heartbeating
+  // cannot be restarted after it has been stopped, A new sender must be created
+  // instead.
+  void Stop();
 
  private:
-  void DoStart();
+  FRIEND_TEST_ALL_PREFIXES(HeartbeatSenderTest, DoSendStanza);
+  FRIEND_TEST_ALL_PREFIXES(HeartbeatSenderTest, CreateHeartbeatMessage);
+
+  enum State {
+    CREATED,
+    INITIALIZED,
+    STARTED,
+    STOPPED,
+  };
+
   void DoSendStanza();
 
+  // Helper methods used by DoSendStanza() to generate heartbeat stanzas.
+  // Caller owns the result.
+  buzz::XmlElement* CreateHeartbeatMessage();
+  buzz::XmlElement* CreateSignature();
+
   void ProcessResponse(const buzz::XmlElement* response);
 
-  bool started_;
+  State state_;
   scoped_refptr<MutableHostConfig> config_;
   JingleClient* jingle_client_;
   scoped_ptr<IqRequest> request_;
   std::string host_id_;
+  HostKeyPair key_pair_;
 };
 
 }  // namespace remoting