libt2n: (gerd) some documentation improvement as preparation for release

[libt2n] / src / command_client.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 <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/serialization/serialization.hpp>

#include <boost/bind.hpp>

#include "command_client.hxx"

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

using namespace std;

namespace libt2n
{

command_client::command_client(client_connection* _c, long long _command_timeout_usec, long long _hello_timeout_usec)
    : c(_c)
{
    command_timeout_usec=_command_timeout_usec;
    hello_timeout_usec=_hello_timeout_usec;

    // for reconnects
    c->add_callback(new_connection,bind(&command_client::read_hello, boost::ref(*this)));

    // don't expect hello from an always closed connection (like dummy_client_connection)
    if (!is_connection_closed())
    {
        try
        {
            read_hello();
        }
        catch (t2n_communication_error &e)
        {
            c->close();

            // store a copy of the exception that you can find out details about the error later
            std::auto_ptr<t2n_exception> tmp(e.clone());
            constructorException=tmp;
        }
        catch (...)
        {
            throw;
        }
    }
}

/** @brief replace the connection currently in use with a new one
    @param _c pointer to the new connection

    @note the old connection must still be valid when this method is called,
          it can safely be deleted after this method returned

    @note all callbacks registered on the old connection will be copied over
          to the new one
*/
void command_client::replace_connection(client_connection* _c)
{
    // copy all callbacks registered on the old connection
    for(callback_event_type e=static_cast<callback_event_type>(0);
        e < __events_end;
        e=static_cast<callback_event_type>(static_cast<int>(e)+1))
    {
        list<boost::function<void ()> > evcb=c->get_callback_list(e);

        for (list<boost::function<void ()> >::iterator i=evcb.begin(); i != evcb.end(); i++)
            _c->add_callback(e,*i);
    }

    // replace the connection
    c=_c;

    read_hello();
}

/** @brief return a complete packet
    @param usec_timeout maximum microseconds to wait until the packet is complete
    @retval packet data as std::string

    @note throws a t2n_transfer_error if the timeout is exceeded
*/
std::string command_client::read_packet(const long long &usec_timeout)
{
    string resultpacket;
    bool got_packet=false;
    long long my_timeout=usec_timeout;
    while(!(got_packet=c->get_packet(resultpacket)) && my_timeout > 0  && !c->is_closed())
        c->fill_buffer(my_timeout,&my_timeout);

    if (!got_packet)
        throw t2n_transfer_error("timeout exceeded");

    return resultpacket;
}

/** @brief read and check the hello message at the beginning of a connection

    @note throws exceptions if something went wrong
*/
void command_client::read_hello()
{
    string resultpacket;
    bool got_packet=false;
    long long my_timeout=hello_timeout_usec;
    while(!(got_packet=c->get_packet(resultpacket)) && my_timeout > 0  && !c->is_closed())
    {
        c->fill_buffer(my_timeout,&my_timeout);

        c->peek_packet(resultpacket);
        check_hello(resultpacket);           // will throw before timeout if wrong data received
    }

    if (!got_packet)
        throw t2n_transfer_error("timeout exceeded");

    if (!check_hello(resultpacket))
        throw t2n_version_mismatch("illegal hello received (incomplete): "+resultpacket);
}

/** @brief check if a hello message is valid
    @param hellostr std::string with the message to check
    @retval true if the hello is good and complete

    @note you can check incomplete hellos. you will get a false return value
          but no exception. throws exceptions as soon as something is wrong.
*/
bool command_client::check_hello(const std::string& hellostr)
{
    istringstream hello(hellostr);

    char chk;

    if (hello.read(&chk,1))
    {
        if (chk != 'T')
            throw t2n_version_mismatch("illegal hello received (T2N)");
    }
    else
        return false;

    if (hello.read(&chk,1))
    {
        if (chk != '2')
            throw t2n_version_mismatch("illegal hello received (T2N)");
    }
    else
        return false;

    if (hello.read(&chk,1))
    {
        if (chk != 'N')
            throw t2n_version_mismatch("illegal hello received (T2N)");
    }
    else
        return false;

    if (hello.read(&chk,1))
    {
        if (chk != 'v')
            throw t2n_version_mismatch("illegal hello received (T2N)");
    }
    else
        return false;

    int prot_version;
    if (hello >> prot_version)
    {
        if (prot_version != PROTOCOL_VERSION)
            throw t2n_version_mismatch("not compatible with the server protocol version");
    }
    else
        return false;

    if (hello.read(&chk,1))
    {
        if (chk != ';')
            throw t2n_version_mismatch("illegal hello received (1. ;)");
    }
    else
        return false;

    unsigned int hbo;
    if (hello.read((char*)&hbo,sizeof(hbo)))
    {
        if (hbo != 1)
            throw t2n_version_mismatch("host byte order not matching");
    }
    else
        return false;

    if (hello.read(&chk,1))
    {
        if (chk != ';')
            throw t2n_version_mismatch("illegal hello received (2. ;)");
    }
    else
        return false;

    return true;
}

/** @brief send a command to the server and store the result
    @param cmd pointer to a command-object
    @param[out] res result container to store the result in

    @note you can check incomplete hellos. you will get a false return value
          but no exception. throws exceptions as soon as something is wrong.
*/
void command_client::send_command(command* cmd, result_container &res)
{
    ostringstream ofs;
    command_container cc(cmd);
    boost::archive::binary_oarchive oa(ofs);

    if (is_connection_closed())
        throw t2n_transfer_error("connection to server is closed");

    try
    {
        oa << cc;
    }
    catch(boost::archive::archive_exception &e)
    {
        ostringstream msg;
        msg << "archive_exception while serializing on client-side, code " << e.code << " (" << e.what() << ")";
        throw t2n_serialization_error(msg.str());
    }
    catch(...)
        { throw; }

    std::ostream* ostr;
    if ((ostr=c->get_logstream(fulldebug))!=NULL)
    {
        (*ostr) << "sending command, decoded data: " << std::endl;
        boost::archive::xml_oarchive xo(*ostr);
        xo << BOOST_SERIALIZATION_NVP(cc);
    }

    c->write(ofs.str());

    istringstream ifs(read_packet(command_timeout_usec));
    boost::archive::binary_iarchive ia(ifs);

    try
    {
        ia >> res;
    }
    catch(boost::archive::archive_exception &e)
    {
        ostringstream msg;
        msg << "archive_exception while deserializing on client-side, code " << e.code << " (" << e.what() << ")";
        throw t2n_serialization_error(msg.str());
    }
    catch(...)
        { throw; }

    if ((ostr=c->get_logstream(fulldebug))!=NULL)
    {
        (*ostr) << "received result, decoded data: " << std::endl;
        boost::archive::xml_oarchive xo(*ostr);
        xo << BOOST_SERIALIZATION_NVP(res);
    }
}

}