ftp_session.h

#pragma once

#include <asio.hpp>

#include <deque>
#include <fstream>

#include "ftp_message.h"

#include "filesystem.h"
#include "user_database.h"
#include "ftp_user.h"

#include "win_str_convert.h"

namespace fineftp
{
  class ReadableFile;

  class FtpSession
    : public std::enable_shared_from_this<FtpSession>
  {
  private:
    struct WriteableFile
    {
      WriteableFile(const std::string& filename, std::ios::openmode mode)
#if defined(WIN32) && !defined(__GNUG__)
        : file_stream_(StrConvert::Utf8ToWide(filename), mode)
#else
        : file_stream_(filename, mode)
#endif
        , stream_buffer_(1024 * 1024)
      {
        file_stream_.rdbuf()->pubsetbuf(stream_buffer_.data(), static_cast<std::streamsize>(stream_buffer_.size()));
      }

      // Copy
      WriteableFile(const WriteableFile&)            = delete;
      WriteableFile& operator=(const WriteableFile&) = delete;

      // Move disabled (as we are storing the shared_from_this() pointer in lambda captures)
      WriteableFile& operator=(WriteableFile&&)      = delete;
      WriteableFile(WriteableFile&&)                 = delete;

      ~WriteableFile()
      {
        file_stream_.flush();
        file_stream_.close();
      }

      std::fstream      file_stream_;
      std::vector<char> stream_buffer_;
    };

  ////////////////////////////////////////////////////////
  // Public API
  ////////////////////////////////////////////////////////
  public:
    FtpSession(asio::io_service& io_service, const UserDatabase& user_database, const std::function<void()>& completion_handler);

    // Copy (disabled, as we are inheriting from shared_from_this)
    FtpSession(const FtpSession&)            = delete;
    FtpSession& operator=(const FtpSession&) = delete;

    // Move (disabled, as we are inheriting from shared_from_this)
    FtpSession& operator=(FtpSession&&)      = delete;
    FtpSession(FtpSession&&)                 = delete;

    ~FtpSession();

    void start();

    asio::ip::tcp::socket& getSocket();

  ////////////////////////////////////////////////////////
  // FTP command-socket
  ////////////////////////////////////////////////////////
  private:
    void sendFtpMessage(const FtpMessage& message);
    void sendFtpMessage(FtpReplyCode code, const std::string& message);
    void sendRawFtpMessage(const std::string& raw_message);
    void startSendingMessages();
    void readFtpCommand();

    void handleFtpCommand(const std::string& command);

  ////////////////////////////////////////////////////////
  // FTP Commands
  ////////////////////////////////////////////////////////
  private:
    // Access control commands
    void handleFtpCommandUSER(const std::string& param);
    void handleFtpCommandPASS(const std::string& param);
    void handleFtpCommandACCT(const std::string& param);
    void handleFtpCommandCWD(const std::string& param);
    void handleFtpCommandCDUP(const std::string& param);
    void handleFtpCommandREIN(const std::string& param);
    void handleFtpCommandQUIT(const std::string& param);

    // Transfer parameter commands
    void handleFtpCommandPORT(const std::string& param);
    void handleFtpCommandPASV(const std::string& param);
    void handleFtpCommandTYPE(const std::string& param);
    void handleFtpCommandSTRU(const std::string& param);
    void handleFtpCommandMODE(const std::string& param);

    // Ftp service commands
    void handleFtpCommandRETR(const std::string& param);
    void handleFtpCommandSIZE(const std::string& param);
    void handleFtpCommandSTOR(const std::string& param);
    void handleFtpCommandSTOU(const std::string& param);
    void handleFtpCommandAPPE(const std::string& param);
    void handleFtpCommandALLO(const std::string& param);
    void handleFtpCommandREST(const std::string& param);
    void handleFtpCommandRNFR(const std::string& param);
    void handleFtpCommandRNTO(const std::string& param);
    void handleFtpCommandABOR(const std::string& param);
    void handleFtpCommandDELE(const std::string& param);
    void handleFtpCommandRMD(const std::string& param);
    void handleFtpCommandMKD(const std::string& param);
    void handleFtpCommandPWD(const std::string& param);
    void handleFtpCommandLIST(const std::string& param);
    void handleFtpCommandNLST(const std::string& param);
    void handleFtpCommandSITE(const std::string& param);
    void handleFtpCommandSYST(const std::string& param);
    void handleFtpCommandSTAT(const std::string& param);
    void handleFtpCommandHELP(const std::string& param);
    void handleFtpCommandNOOP(const std::string& param);

    // Modern FTP Commands
    void handleFtpCommandFEAT(const std::string& param);

    void handleFtpCommandOPTS(const std::string& param);

  ////////////////////////////////////////////////////////
  // FTP data-socket send
  ////////////////////////////////////////////////////////
  private:

    void sendDirectoryListing   (const std::map<std::string, Filesystem::FileStatus>& directory_content);
    void sendNameList           (const std::map<std::string, Filesystem::FileStatus>& directory_content);

    void sendFile               (const std::shared_ptr<ReadableFile>&          file);

    void addDataToBufferAndSend (const std::shared_ptr<std::vector<char>>&     data
                               , const std::shared_ptr<asio::ip::tcp::socket>& data_socket
                               , const std::function<void(void)>&              fetch_more = []() {return; });

    void writeDataToSocket      (const std::shared_ptr<asio::ip::tcp::socket>& data_socket
                               , const std::function<void(void)>&              fetch_more);

  ////////////////////////////////////////////////////////
  // FTP data-socket receive
  ////////////////////////////////////////////////////////
  private:
    void receiveFile(const std::shared_ptr<WriteableFile>& file);

    void receiveDataFromSocketAndWriteToFile(const std::shared_ptr<WriteableFile>&         file
                                           , const std::shared_ptr<asio::ip::tcp::socket>& data_socket);

    void writeDataToFile(const std::shared_ptr<std::vector<char>>& data
                       , const std::shared_ptr<WriteableFile>&     file
                       , const std::function<void(void)>&          fetch_more = []() {return; });

    void endDataReceiving(const std::shared_ptr<WriteableFile>& file);

  ////////////////////////////////////////////////////////
  // Helpers
  ////////////////////////////////////////////////////////
  private:
    std::string toAbsoluteFtpPath(const std::string& rel_or_abs_ftp_path) const;
    std::string toLocalPath(const std::string& ftp_path) const;
    static std::string createQuotedFtpPath(const std::string& unquoted_ftp_path);

    /** @brief Checks if a path is renamable
    *
    * Checks if the current user can rename the given path. A path is renameable
    * if it exists, a user is logged in and the user has sufficient permissions
    * (file / dir / both) to rename it.
    *
    * @param ftp_path: The source path
    * 
    * @return (COMMAND_OK, "") if the path can be renamed or any other meaningfull error message if not.
    */
    FtpMessage checkIfPathIsRenamable(const std::string& ftp_path) const;

    FtpMessage executeCWD(const std::string& param);

#ifdef WIN32
    /**
     * @brief Returns Windows' GetLastError() as human readable string
     * @return The message of the last error
     */
    static std::string GetLastErrorStr();
#endif // WIN32

  ////////////////////////////////////////////////////////
  // Member variables
  ////////////////////////////////////////////////////////
  private:
    // Completion handler
    const std::function<void()> completion_handler_;

    // User management
    const UserDatabase&      user_database_;
    std::shared_ptr<FtpUser> logged_in_user_;

    // "Global" io service
    asio::io_service&        io_service_;

    // Command Socket
    asio::ip::tcp::socket    command_socket_;
    asio::io_service::strand command_write_strand_;
    asio::streambuf          command_input_stream_;
    std::deque<std::string>  command_output_queue_;

    std::string last_command_;
    std::string rename_from_path_;
    std::string username_for_login_;

    // Data Socket (=> passive mode)
    bool                                           data_type_binary_;
    asio::ip::tcp::acceptor                        data_acceptor_;
    std::weak_ptr<asio::ip::tcp::socket>           data_socket_weakptr_;
    std::deque<std::shared_ptr<std::vector<char>>> data_buffer_;
    asio::io_service::strand                       data_buffer_strand_;
    asio::io_service::strand                       file_rw_strand_;

    // Current state
    std::string ftp_working_directory_;
  };
}