Refactor CastSocket code for the following:

chrome/browser/extensions/api/cast_channel/cast_socket.h

 // 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 CHROME_BROWSER_EXTENSIONS_API_CAST_CHANNEL_CAST_SOCKET_H_
 #define CHROME_BROWSER_EXTENSIONS_API_CAST_CHANNEL_CAST_SOCKET_H_
 
 #include <queue>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "chrome/browser/extensions/api/api_resource.h"
 #include "chrome/browser/extensions/api/api_resource_manager.h"
+#include "chrome/browser/extensions/api/cast_channel/cast_channel.pb.h"
 #include "chrome/common/extensions/api/cast_channel.h"
 #include "net/base/completion_callback.h"
 #include "net/base/io_buffer.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_log.h"
 #include "url/gurl.h"
 
 namespace net {
 class AddressList;
 class CertVerifier;
 class SSLClientSocket;
+class StreamSocket;
 class TCPClientSocket;
 class TransportSecurityState;
 }
 
 namespace extensions {
 namespace api {
 namespace cast_channel {
 
-class CastMessage;
-
 // Size, in bytes, of the largest allowed message payload on the wire (without
 // the header).
 extern const uint32 kMaxMessageSize;
 
 // This class implements a channel between Chrome and a Cast device using a TCP
 // socket. The channel may be unauthenticated (cast://) or authenticated
 // (casts://). All CastSocket objects must be used only on the IO thread.
 //
 // NOTE: Not called "CastChannel" to reduce confusion with the generated API
 // code.
 class CastSocket : public ApiResource,
                    public base::SupportsWeakPtr<CastSocket> {
  public:
   // Object to be informed of incoming messages and errors.
   class Delegate {
    public:
     // An error occurred on the channel.
+    // It is fine to delete the socket in this callback.
     virtual void OnError(const CastSocket* socket,
                          ChannelError error) = 0;
-    // A string message was received on the channel.
+    // A message was received on the channel.
+    // Do NOT delete the socket in this callback.
     virtual void OnMessage(const CastSocket* socket,
                            const MessageInfo& message) = 0;
    protected:
     virtual ~Delegate() {}
   };
 
   // Creates a new CastSocket to |url|. |owner_extension_id| is the id of the
   // extension that opened the socket.
   CastSocket(const std::string& owner_extension_id,
              const GURL& url,
              CastSocket::Delegate* delegate,
              net::NetLog* net_log);
   virtual ~CastSocket();
 
   // The URL for the channel.
   const GURL& url() const;
 
   // Whether to perform receiver authentication.
   bool auth_required() const { return auth_required_; }
 
   // Channel id for the ApiResourceManager.
   int id() const { return channel_id_; }
 
   // Sets the channel id.
   void set_id(int channel_id) { channel_id_ = channel_id; }
 
   // Returns the state of the channel.
   ReadyState ready_state() const { return ready_state_; }
 
-  // Returns the last error that occurred on this channel, or CHANNEL_ERROR_NONE
-  // if no error has occurred.
+  // Returns the last error that occurred on this channel, or
+  // CHANNEL_ERROR_NONE if no error has occurred.
   ChannelError error_state() const { return error_state_; }
 
   // Connects the channel to the peer. If successful, the channel will be in
   // READY_STATE_OPEN.
+  // It is fine to delete the CastSocket object in |callback|.
   virtual void Connect(const net::CompletionCallback& callback);
 
   // Sends a message over a connected channel. The channel must be in
   // READY_STATE_OPEN.
+  //
+  // Note that if an error occurs the following happens:
+  // 1. Completion callbacks for all pending writes are invoked with error.
+  // 2. Delegate::OnError is called once.
+  // 3. Castsocket is closed.
+  //
+  // DO NOT delete the CastSocket object in write completion callback.
+  // But it is fine to delete the socket in Delegate::OnError
   virtual void SendMessage(const MessageInfo& message,
                            const net::CompletionCallback& callback);
 
   // Closes the channel. On completion, the channel will be in
   // READY_STATE_CLOSED.
+  // It is fine to delete the CastSocket object in |callback|.
   virtual void Close(const net::CompletionCallback& callback);
 
   // Fills |channel_info| with the status of this channel.
   virtual void FillChannelInfo(ChannelInfo* channel_info) const;
 
  protected:
   // Creates an instance of TCPClientSocket.
   virtual scoped_ptr<net::TCPClientSocket> CreateTcpSocket();
-  // Creates an instance of SSLClientSocket.
-  virtual scoped_ptr<net::SSLClientSocket> CreateSslSocket();
+  // Creates an instance of SSLClientSocket with the given underlying |socket|.
+  virtual scoped_ptr<net::SSLClientSocket> CreateSslSocket(
+      scoped_ptr<net::StreamSocket> socket);
+  // Returns IPEndPoint for the URL to connect to.
+  const net::IPEndPoint& ip_endpoint() const { return ip_endpoint_; }
   // Extracts peer certificate from SSLClientSocket instance when the socket
   // is in cert error state.
   // Returns whether certificate is successfully extracted.
   virtual bool ExtractPeerCert(std::string* cert);
-  // Sends a challenge request to the receiver.
-  virtual int SendAuthChallenge();
-  // Reads auth challenge reply from the receiver.
-  virtual int ReadAuthChallengeReply();
   // Verifies whether the challenge reply received from the peer is valid:
   // 1. Signature in the reply is valid.
   // 2. Certificate is rooted to a trusted CA.
   virtual bool VerifyChallengeReply();
 
-  // Returns whether we are executing in a valid thread.
-  virtual bool CalledOnValidThread() const;
-
  private:
   friend class ApiResourceManager<CastSocket>;
   friend class CastSocketTest;
 
   static const char* service_name() {
     return "CastSocketManager";
   }
 
   // Internal connection states.
   enum ConnectionState {
     CONN_STATE_NONE,
     CONN_STATE_TCP_CONNECT,
     CONN_STATE_TCP_CONNECT_COMPLETE,
     CONN_STATE_SSL_CONNECT,
     CONN_STATE_SSL_CONNECT_COMPLETE,
     CONN_STATE_AUTH_CHALLENGE_SEND,
     CONN_STATE_AUTH_CHALLENGE_SEND_COMPLETE,
     CONN_STATE_AUTH_CHALLENGE_REPLY_COMPLETE,
   };
 
+  // Internal write states.
+  enum WriteState {
+    WRITE_STATE_NONE,
+    WRITE_STATE_WRITE,
+    WRITE_STATE_WRITE_COMPLETE,
+    WRITE_STATE_DO_CALLBACK,
+    WRITE_STATE_ERROR,
+  };
+
+  // Internal read states.
+  enum ReadState {
+    READ_STATE_NONE,
+    READ_STATE_READ,
+    READ_STATE_READ_COMPLETE,
+    READ_STATE_DO_CALLBACK,
+    READ_STATE_ERROR,
+  };
+
   /////////////////////////////////////////////////////////////////////////////
   // Following methods work together to implement the following flow:
   // 1. Create a new TCP socket and connect to it
   // 2. Create a new SSL socket and try connecting to it
   // 3. If connection fails due to invalid cert authority, then extract the
   //    peer certificate from the error.
   // 4. Whitelist the peer certificate and try #1 and #2 again.
   // 5. If SSL socket is connected successfully, and if protocol is casts://
   //    then issue an auth challenge request.
   // 6. Validate the auth challenge response.
-
+  //
   // Main method that performs connection state transitions.
-  int DoConnectLoop(int result);
+  void DoConnectLoop(int result);
   // Each of the below Do* method is executed in the corresponding
-  // connection state. For e.g. when connection state is TCP_CONNECT
+  // connection state. For example when connection state is TCP_CONNECT
   // DoTcpConnect is called, and so on.
   int DoTcpConnect();
   int DoTcpConnectComplete(int result);
   int DoSslConnect();
   int DoSslConnectComplete(int result);
   int DoAuthChallengeSend();
   int DoAuthChallengeSendComplete(int result);
   int DoAuthChallengeReplyComplete(int result);
   /////////////////////////////////////////////////////////////////////////////
 
-  // Callback method for callbacks from underlying sockets.
-  void OnConnectComplete(int result);
+  /////////////////////////////////////////////////////////////////////////////
+  // Following methods work together to implement write flow.
+  //
+  // Main method that performs write flow state transitions.
+  void DoWriteLoop(int result);
+  // Each of the below Do* method is executed in the corresponding
+  // write state. For e.g. when write state is WRITE_STATE_WRITE_COMPLETE

[Ryan Sleevi, 2013/12/12 00:48:14]

Still says "For e.g." (and there are multiple occurrences in this file)

[Munjal (Google), 2013/12/12 17:53:47]

Done.

+  // DowriteComplete is called, and so on.
+  int DoWrite();
+  int DoWriteComplete(int result);
+  int DoWriteCallback();
+  int DoWriteError(int result);
+  /////////////////////////////////////////////////////////////////////////////
 
-  // Callback method when a challenge request is sent or a reply is received.
-  void OnChallengeEvent(int result);
+  /////////////////////////////////////////////////////////////////////////////
+  // Following methods work together to implement read flow.
+  //
+  // Main method that performs write flow state transitions.
+  void DoReadLoop(int result);
+  // Each of the below Do* method is executed in the corresponding
+  // write state. For e.g. when write state is READ_STATE_READ_COMPLETE
+  // DoReadComplete is called, and so on.
+  int DoRead();
+  int DoReadComplete(int result);
+  int DoReadCallback();
+  int DoReadError(int result);
+  /////////////////////////////////////////////////////////////////////////////
 
   // Runs the external connection callback and resets it.
   void DoConnectCallback(int result);
-
   // Verifies that the URL is a valid cast:// or casts:// URL and sets url_ to
   // the result.
   bool ParseChannelUrl(const GURL& url);
-
-  // Sends the given |message| and invokes the given callback when done.
-  int SendMessageInternal(const CastMessage& message,
-                          const net::CompletionCallback& callback);
-
-  // Writes data to the socket from the WriteRequest at the head of the queue.
-  // Calls OnWriteData() on completion.
-  int WriteData();
-  void OnWriteData(int result);
-
-  // Reads data from the socket into one of the read buffers. Calls
-  // OnReadData() on completion.
-  int ReadData();
-  void OnReadData(int result);
-
-  // Processes the contents of header_read_buffer_ and returns true on success.
+  // Adds |message| to the write queue and starts the write loop if needed.
+  void SendCastMessageInternal(const CastMessage& message,
+                               const net::CompletionCallback& callback);
+  void PostTaskToStartConnectLoop(int result);
+  void PostTaskToStartReadLoop();
+  void StartReadLoop();
+  // Parses the contents of header_read_buffer_ and sets current_message_size_
+  // to the size of the body of the message.
   bool ProcessHeader();
-  // Processes the contents of body_read_buffer_ and returns true on success.
+  // Parses the contents of body_read_buffer_ and sets current_message_ to
+  // the message received.
   bool ProcessBody();
-  // Parses the message held in body_read_buffer_ and notifies |delegate_| if a
-  // message was extracted from the buffer.  Returns true on success.
-  bool ParseMessageFromBody();
-
+  // Closes socket, updating the error state and signaling the delegate that
+  // |error| has occurred.
+  void CloseWithError(ChannelError error);
   // Serializes the content of message_proto (with a header) to |message_data|.
   static bool Serialize(const CastMessage& message_proto,
                         std::string* message_data);
 
-  // Closes the socket and sets |error_state_|. Also signals |error| via
-  // |delegate_|.
-  void CloseWithError(ChannelError error);
+  // Returns whether we are executing in a valid thread.

[Ryan Sleevi, 2013/12/12 00:48:14]

You introduced another pronoun comment.

It's also not clear why this is virtual. And it's just a forward to the
ThreadChecker, is it not?

[Munjal (Google), 2013/12/12 17:53:47]

- Removed comment since it felt redundant anyway.
- virtual is a residue from something I was trying out. Removed now. 
- Yes, it is a forward to the thread checker.

+  virtual bool CalledOnValidThread() const;
 
   base::ThreadChecker thread_checker_;
 
   // The id of the channel.
   int channel_id_;
 
   // The URL of the peer (cast:// or casts://).
   GURL url_;
   // Delegate to inform of incoming messages and errors.
   Delegate* delegate_;
   // True if we should perform receiver authentication.
   bool auth_required_;
   // The IP endpoint of the peer.
   net::IPEndPoint ip_endpoint_;
-  // The last error encountered by the channel.
-  ChannelError error_state_;
-  // The current status of the channel.
-  ReadyState ready_state_;
-
-  // True when there is a write callback pending.
-  bool write_callback_pending_;
-  // True when there is a read callback pending.
-  bool read_callback_pending_;
 
   // IOBuffer for reading the message header.
   scoped_refptr<net::GrowableIOBuffer> header_read_buffer_;
   // IOBuffer for reading the message body.
   scoped_refptr<net::GrowableIOBuffer> body_read_buffer_;
   // IOBuffer we are currently reading into.
   scoped_refptr<net::GrowableIOBuffer> current_read_buffer_;
   // The number of bytes in the current message body.
   uint32 current_message_size_;
+  // Last message received on the socket.
+  CastMessage current_message_;
 
   // The NetLog for this service.
   net::NetLog* net_log_;
   // The NetLog source for this service.
   net::NetLog::Source net_log_source_;
 
-  // Next connection state to transition to.
-  ConnectionState next_state_;
   // Owned ptr to the underlying TCP socket.
   scoped_ptr<net::TCPClientSocket> tcp_socket_;
   // Owned ptr to the underlying SSL socket.
   scoped_ptr<net::SSLClientSocket> socket_;
   // Certificate of the peer. This field may be empty if the peer
   // certificate is not yet fetched.
   std::string peer_cert_;
   scoped_ptr<net::CertVerifier> cert_verifier_;
   scoped_ptr<net::TransportSecurityState> transport_security_state_;
   // Reply received from the receiver to a challenge request.
   scoped_ptr<CastMessage> challenge_reply_;
 
   // Callback invoked when the socket is connected.
   net::CompletionCallback connect_callback_;
 
+  // Connection flow state machine state.
+  ConnectionState connect_state_;
+  // Write flow state machine state.
+  WriteState write_state_;
+  // Read flow state machine state.
+  ReadState read_state_;
+  // The last error encountered by the channel.
+  ChannelError error_state_;
+  // The current status of the channel.
+  ReadyState ready_state_;
+
   // Message header struct. If fields are added, be sure to update
   // kMessageHeaderSize in the .cc.
   struct MessageHeader {
     MessageHeader();
     // Sets the message size.
     void SetMessageSize(size_t message_size);
     // Prepends this header to |str|.
     void PrependToString(std::string* str);
     // Reads |header| from the beginning of |buffer|.
     static void ReadFromIOBuffer(net::GrowableIOBuffer* buffer,
@@ skipping 12 matching lines @@
     // and prepending the header.  Must only be called once.
     bool SetContent(const CastMessage& message_proto);
 
     net::CompletionCallback callback;
     scoped_refptr<net::DrainableIOBuffer> io_buffer;
   };
   // Queue of pending writes. The message at the front of the queue is the one
   // being written.
   std::queue<WriteRequest> write_queue_;
 
-  // Used to protect against DoConnectLoop() re-entrancy.
-  bool in_connect_loop_;
-
   FRIEND_TEST_ALL_PREFIXES(CastSocketTest, TestCastURLs);
   FRIEND_TEST_ALL_PREFIXES(CastSocketTest, TestRead);
   FRIEND_TEST_ALL_PREFIXES(CastSocketTest, TestReadMany);
+  FRIEND_TEST_ALL_PREFIXES(CastSocketTest, TestFullSecureConnectionFlowAsync);
   DISALLOW_COPY_AND_ASSIGN(CastSocket);
 };
 
 }  // namespace cast_channel
 }  // namespace api
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_CAST_CHANNEL_CAST_SOCKET_H_