libt2n: (gerd) more documentation-polishing

[libt2n] / src / connection.cpp

/***************************************************************************
 *   Copyright (C) 2006 by Gerd v. Egidy                                   *
 *   gve@intra2net.com                                                     *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU Lesser General Public License version   *
 *   2.1 as published by the Free Software Foundation.                     *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU Lesser General Public License for more details.                   *
 *                                                                         *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this program; if not, write to the                 *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

#include <string>
#include <sstream>
#include <iostream>
#include <stdexcept>

#include <netinet/in.h>

#include "connection.hxx"

namespace libt2n
{

connection::~connection()
{
    // we want the connection_closed callbacks to be called before
    close();

    do_callbacks(connection_deleted);
}

void connection::close()
{
    if (!is_closed())
    {
        closed=true;
        do_callbacks(connection_closed);
    }
}

/// get the number of bytes being available as next complete packet
connection::packet_size_indicator connection::bytes_available()
{
    // no size information -> no packet
    if (buffer.size() < sizeof(packet_size_indicator))
        return 0;

    packet_size_indicator psize=ntohl(*((packet_size_indicator*)(buffer.data())));

    // enough data for one packet in buffer?
    if (buffer.size() < sizeof(packet_size_indicator)+psize)
        return 0;

    // ok, full packet there
    return psize;
}

/** @brief read a complete data packet from the buffer. The packet is removed from the
            connection buffer.
    @param[out] data the data package
    @retval true if packet found
*/
bool connection::get_packet(std::string& data)
{
    packet_size_indicator psize;

    if ((psize=bytes_available()))
    {
        data.assign(buffer,sizeof(packet_size_indicator),psize);
        buffer.erase(0,sizeof(packet_size_indicator)+psize);
        return true;
    }
    else
        return false;
}

/** @brief get (maybe incomplete) data of the next packet from the buffer. Does not remove the data
            from the connection buffer.
    @param[out] data the data package
    @retval full size of the packet when it will be complete
*/
unsigned int connection::peek_packet(std::string& data)
{
    // no size information -> no packet
    if (buffer.size() < sizeof(packet_size_indicator))
        return 0;

    packet_size_indicator psize=ntohl(*((packet_size_indicator*)(buffer.data())));

    // not the full data available?
    packet_size_indicator currsize=psize;
    if (buffer.size() < currsize+sizeof(packet_size_indicator))
        currsize=buffer.size()-sizeof(packet_size_indicator);

    data.assign(buffer,sizeof(packet_size_indicator),currsize);

    return psize;
}

/// remove all data from buffer that is not a complete packet
void connection::remove_incomplete_packets()
{
    std::string::size_type p=0;
    std::string::size_type end=buffer.size();

    while (p < end)
    {
        // not enough space for size information -> no packet
        if (p+sizeof(packet_size_indicator) > end)
            break;

        packet_size_indicator psize=ntohl(*((packet_size_indicator*)(buffer.data()+p)));

        if (p+sizeof(packet_size_indicator)+psize > end)
        {
            // incomplete packet
            break;
        }
        else
        {
            // move p to where the next packet will start
            p+=sizeof(packet_size_indicator)+psize;
        }
    }

    if (p < end)
    {
        // incomplete packets there, remove them
        buffer.erase(p);
    }
}

/// send a blob to the peer
void connection::write(const std::string& data)
{
    // prepend packet size to data
    packet_size_indicator psize=htonl(data.size());
    std::string send_data(data);
    send_data.insert(0,(char*)&psize,sizeof(packet_size_indicator));

    real_write(send_data);
}

/** @brief add a callback

    @param event event the function will be called at
    @param func functor (see boost function) that will be called

    @note use boost::bind to bind to member functions and parameters like this:
        17 is a fixed parameter that is always added to the call
        c.add_callback(connection_closed,bind(&my_class::func_to_call_back, boost::ref(*this), 17));
*/
void connection::add_callback(callback_event_type event, const boost::function<void ()>& func)
{
    callbacks[event].push_back(func);
}

/** @brief an event has occured, execute the callbacks that are registered for this event

    @param event event type that has occured
*/
void connection::do_callbacks(callback_event_type event)
{
    std::list<boost::function<void ()> >::iterator i,ie=callbacks[event].end();
    for (i=callbacks[event].begin(); i != ie; i++)
        (*i)();
}

/** @brief get the callbacks in place for one event

    @param event event the callbacks should be registered for
    @return std::list of functors (boost::function) with the callbacks

    @note if you want to get the callbacks for all events, loop from 0 to __events_end 
*/
std::list<boost::function<void ()> > connection::get_callback_list(callback_event_type event)
{
    return callbacks[event];
}

/** @brief reopen a already closed connection, removes incomplete packets from the buffer

    @note Only call when the connection is closed.

    @note Justs cares about the data of connection, reconnecting has to be
          done in a derived class.
*/
void connection::reopen()
{
    if (!is_closed())
        throw std::logic_error("connection::reopen() called with connection still open");

    closed=false;

    // incomplete buffer data is worthless with a new connection
    remove_incomplete_packets();

    do_callbacks(new_connection);
}

}