boost 1.59之 boost::asio::ssl (5)

下面是boost官方给出的ssl服务端例子： 

首先，声明了一个流类型的socekt 用来作为socket对象：

  1: typedef boost::asio::ssl::stream<boost::asio::ip::tcp::socket> ssl_socket;

接下来是session类：

  1: class session

  2: {

  3: public:

  4:   session(boost::asio::io_service& io_service,

  5:       boost::asio::ssl::context& context)

  6:     : socket_(io_service, context)

  7:   {

  8:   }

  9:

 10:   ssl_socket::lowest_layer_type& socket()

 11:   {

 12:     return socket_.lowest_layer();

 13:   }

 14:

 15:   void start()

 16:   {

 17:     socket_.async_handshake(boost::asio::ssl::stream_base::server,

 18:         boost::bind(&session::handle_handshake, this,

 19:           boost::asio::placeholders::error));

 20:   }

 21:

 22:   void handle_handshake(const boost::system::error_code& error)

 23:   {

 24:     if (!error)

 25:     {

 26:       socket_.async_read_some(boost::asio::buffer(data_, max_length),

 27:           boost::bind(&session::handle_read, this,

 28:             boost::asio::placeholders::error,

 29:             boost::asio::placeholders::bytes_transferred));

 30:     }

 31:     else

 32:     {

 33:       delete this;

 34:     }

 35:   }

 36:

 37:   void handle_read(const boost::system::error_code& error,

 38:       size_t bytes_transferred)

 39:   {

 40:     if (!error)

 41:     {

 42:       boost::asio::async_write(socket_,

 43:           boost::asio::buffer(data_, bytes_transferred),

 44:           boost::bind(&session::handle_write, this,

 45:             boost::asio::placeholders::error));

 46:     }

 47:     else

 48:     {

 49:       delete this;

 50:     }

 51:   }

 52:

 53:   void handle_write(const boost::system::error_code& error)

 54:   {

 55:     if (!error)

 56:     {

 57:       socket_.async_read_some(boost::asio::buffer(data_, max_length),

 58:           boost::bind(&session::handle_read, this,

 59:             boost::asio::placeholders::error,

 60:             boost::asio::placeholders::bytes_transferred));

 61:     }

 62:     else

 63:     {

 64:       delete this;

 65:     }

 66:   }

 67:

 68: private:

 69:   ssl_socket socket_;

 70:   enum { max_length = 1024 };

 71:   char data_[max_length];

 72: };

session类 ，主要的功能就是通信，做一些数据处理的操作。session类声明了3个私有的变量，一个socket，一个枚举的长度值max_length，一个data_作为缓冲区。

session类，提供了2个成员函数，3个回调函数，2个成员函数，第一个socket()的功能是获取一个底层的ssl_socket,第二个start函数的作用是进行通信。

在start()函数中，使用ssl_socket 进行handshake操作，进行数据交互，其回调函数hand_handshake回调成功，则执行读操作，后续是一样的过程；

session类最重要的还是数据的操作，ssl_socket提供了socket加密，此处可忽略数据的加密。

下面是server类：

  1: class server

  2: {

  3: public:

  4:   server(boost::asio::io_service& io_service, unsigned short port)

  5:     : io_service_(io_service),

  6:       acceptor_(io_service,

  7:           boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), port)),

  8:       context_(boost::asio::ssl::context::sslv23)

  9:   {

 10:     context_.set_options(                                                           //设置了context的选项

 11:         boost::asio::ssl::context::default_workarounds

 12:         | boost::asio::ssl::context::no_sslv2

 13:         | boost::asio::ssl::context::single_dh_use);

 14:     context_.set_password_callback(boost::bind(&server::get_password, this));       //设置回调函数,获取密码

 15:     context_.use_certificate_chain_file("server.pem");

 16:     context_.use_private_key_file("server.pem", boost::asio::ssl::context::pem);

 17:     context_.use_tmp_dh_file("dh512.pem");

 18:

 19:     start_accept();

 20:   }

 21:

 22:   std::string get_password() const                                                //context的回调函数，用于获取密码

 23:   {

 24:     return "test";

 25:   }

 26:

 27:   void start_accept()                                                              //start_accept 执行连接客户端操作

 28:   {

 29:     session* new_session = new session(io_service_, context_);

 30:     acceptor_.async_accept(new_session->socket(),

 31:         boost::bind(&server::handle_accept, this, new_session,

 32:           boost::asio::placeholders::error));

 33:   }

 34:

 35:   void handle_accept(session* new_session,                                          //执行回调函数

 36:       const boost::system::error_code& error)

 37:   {

 38:     if (!error)

 39:     {

 40:       new_session->start();

 41:     }

 42:     else

 43:     {

 44:       delete new_session;

 45:     }

 46:

 47:     start_accept();

 48:   }

 49:

 50: private:

 51:   boost::asio::io_service& io_service_;

 52:   boost::asio::ip::tcp::acceptor acceptor_;

 53:   boost::asio::ssl::context context_;

 54: };

总结：

        总的来说，通过ssl的服务端程序，和没有使用ssl的服务端程序的流程是一样的，都是 获取客户端连接->连接成功->执行session通信。

那么，不一样的地方，就是在server类中，需要根据需求设置context 的选项实现加密；boost官方给的例子很简单，实现了一个小小的加密socket的服务端程序，

剩下的功能就需要我们根据自己的需求实现拓展。

东西很简单，如果你有疑问，欢迎评论。。。。有则改之无则加勉！！！