Re: [Boost-users] [ASIO] Wrong usage of streambuf ?

Date: Tue, 08 Dec 2009 15:03:46 +0100 From: Axel To: boost-users@lists.boost.org Subject: [Boost-users] [ASIO] Wrong usage of streambuf ? Message-ID: <4B1E5CC2.6040103@laposte.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 Hello

I m writing a simple client/server program. On a request the server answers "ok\r\n". It works well. I have a problem with the client. Using async functions, I don't manage to handle the response from the server. Once the server sent the response, I want to read the data, close the socket, and open a new connection to the server.

When I don't read the data sent by the server, I manage to close the socket and repeat the operation (close the socket, and reconnect to the server). When I read the data, the program seems to block.

/* Callback to the async_write function. On any request, the server sends "ok\r_n" */ void Client::handle_write(boost::asio::ip::tcp::socket* socket, const boost::system::error_code& err) {     if(!err)     {         cout << "Read..." << endl ;     // response_ is a boost::asio::streambuf variable         boost::asio::async_read_until(*socket, response_, "\r\n", boost::bind(&Client::handle_read, this, socket, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)) ;     }     else     {         cout << "Error when writing to host: " << err.message() << "\n" ;     } }

void Client::handle_read(boost::asio::ip::tcp::socket* socket, const boost::system::error_code& err, size_t bytes_transferred) {     cout << bytes_transferred << " bytes received. " << endl ;

    /* Dont count the 2 bytes long "\r\n" string */     int message_size = bytes_transferred - 2 ;

    char * response_char = new char[message_size + 1] ;     response_char[message_size] = '\0' ;     response_stream.read(response_char, message_size) ;     string result(response_char) ;     delete response_char ;     response_.consume(2) ;

    socket->close() ;     delete socket ;     connect() ;     return ; }

If I skip the block where I read the response_ into a string, the program works flawlessly. If I try to read the response from the streambuf variable, the program is blocked at the next call to async_read_until() */ So I guess that I m doing something wrong with the streambuf variable named "response_", but I dont understand what. Can someone explain me what is wrong ?

Thanks in advance.

I am not really sure what response_stream is, but I see what you are trying to do. Consider doing the following instead: void Client::handle_read(boost::asio::ip::tcp::socket* socket, const boost::system::error_code& err, size_t bytes_transferred) { ... //Note: data, will contain the "ok\r\n".. so just do some string manip to get rid of it const char* data=boost::asio::buffer_cast(response_.data()); response_.consume(bytes_transferred); //This is the key... ... }