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q3socketdevice.cpp

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** This file is part of the Qt3Support module of the Qt Toolkit.
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#include "q3socketdevice.h"
#ifndef QT_NO_NETWORK

#include "qwindowdefs.h"
#include <string.h>


//#define Q3SOCKETDEVICE_DEBUG


class Q3SocketDevicePrivate
{
public:
    Q3SocketDevicePrivate( Q3SocketDevice::Protocol p )
      : protocol(p)
    { }

    Q3SocketDevice::Protocol protocol;
};


/*!
    \class Q3SocketDevice
    \brief The Q3SocketDevice class provides a platform-independent low-level socket API.

    \compat
    \reentrant

    This class provides a low level API for working with sockets.  Users of
    this class are assumed to have networking experience. For most users the
    Q3Socket class provides a much easier and high level alternative, but
    certain things (like UDP) can't be done with Q3Socket and if you need a
    platform-independent API for those, Q3SocketDevice is the right choice.

    The essential purpose of the class is to provide a QIODevice that
    works on sockets, wrapped in a platform-independent API.

    When calling connect() or bind(), Q3SocketDevice detects the
    protocol family (IPv4, IPv6) automatically. Passing the protocol
    family to Q3SocketDevice's constructor or to setSocket() forces
    creation of a socket device of a specific protocol. If not set, the
    protocol will be detected at the first call to connect() or bind().

    \sa Q3Socket, QSocketNotifier, QHostAddress
*/


/*!
    \enum Q3SocketDevice::Protocol

    This enum type describes the protocol family of the socket. Possible values
    are:

    \value IPv4 The socket is an IPv4 socket.
    \value IPv6 The socket is an IPv6 socket.
    \value Unknown The protocol family of the socket is not known. This can
         happen if you use Q3SocketDevice with an already existing socket; it
         tries to determine the protocol family, but this can fail if the
         protocol family is not known to Q3SocketDevice.

    \sa protocol() setSocket()
*/

/*!
    \enum Q3SocketDevice::Error

    This enum type describes the error states of Q3SocketDevice.

    \value NoError  No error has occurred.

    \value AlreadyBound  The device is already bound, according to bind().

    \value Inaccessible  The operating system or firewall prohibited
                  the action.

    \value NoResources  The operating system ran out of a resource.

    \value InternalError  An internal error occurred in Q3SocketDevice.

    \value Impossible  An attempt was made to do something which makes
    no sense. For example:
    \code
    ::close( sd->socket() );
    sd->writeBlock( someData, 42 );
    \endcode
    The libc ::close() closes the socket, but Q3SocketDevice is not aware
    of this. So when you call writeBlock(), the impossible happens.

    \value NoFiles  The operating system will not let Q3SocketDevice open
    another file.

    \value ConnectionRefused  A connection attempt was rejected by the
    peer.

    \value NetworkFailure  There is a network failure.

    \value UnknownError  The operating system did something
    unexpected.

    \omitvalue Bug
*/

/*!
    \enum Q3SocketDevice::Type

    This enum type describes the type of the socket:
    \value Stream  a stream socket (TCP, usually)
    \value Datagram  a datagram socket (UDP, usually)
*/


/*!
    Creates a Q3SocketDevice object for the existing socket \a socket.

    The \a type argument must match the actual socket type; use \c
    Q3SocketDevice::Stream for a reliable, connection-oriented TCP
    socket, or Q3SocketDevice::Datagram for an unreliable,
    connectionless UDP socket.
*/
00143 Q3SocketDevice::Q3SocketDevice( int socket, Type type )
    : fd( socket ), t( type ), p( 0 ), pp( 0 ), e( NoError ),
      d(new Q3SocketDevicePrivate(Unknown))
{
#if defined(Q3SOCKETDEVICE_DEBUG)
    qDebug( "Q3SocketDevice: Created Q3SocketDevice %p (socket %x, type %d)",
         this, socket, type );
#endif
    init();
    setSocket( socket, type );
}

/*!
    Creates a Q3SocketDevice object for a stream or datagram socket.

    The \a type argument must be either Q3SocketDevice::Stream for a
    reliable, connection-oriented TCP socket, or \c
    Q3SocketDevice::Datagram for an unreliable UDP socket.

    The socket is created as an IPv4 socket.

    \sa blocking() protocol()
*/
00166 Q3SocketDevice::Q3SocketDevice( Type type )
    : fd( -1 ), t( type ), p( 0 ), pp( 0 ), e( NoError ),
      d(new Q3SocketDevicePrivate(IPv4))
{
#if defined(Q3SOCKETDEVICE_DEBUG)
    qDebug( "Q3SocketDevice: Created Q3SocketDevice object %p, type %d",
          this, type );
#endif
    init();
    setSocket( createNewSocket(), type );
}

/*!
    Creates a Q3SocketDevice object for a stream or datagram socket.

    The \a type argument must be either Q3SocketDevice::Stream for a
    reliable, connection-oriented TCP socket, or \c
    Q3SocketDevice::Datagram for an unreliable UDP socket.

    The \a protocol indicates whether the socket should be of type IPv4
    or IPv6. Passing \c Unknown is not meaningful in this context and you
    should avoid using (it creates an IPv4 socket, but your code is not easily
    readable).

    The argument \a dummy is necessary for compatibility with some
    compilers.

    \sa blocking() protocol()
*/
00195 Q3SocketDevice::Q3SocketDevice( Type type, Protocol protocol, int )
    : fd( -1 ), t( type ), p( 0 ), pp( 0 ), e( NoError ),
      d(new Q3SocketDevicePrivate(protocol))
{
#if defined(Q3SOCKETDEVICE_DEBUG)
    qDebug( "Q3SocketDevice: Created Q3SocketDevice object %p, type %d",
          this, type );
#endif
    init();
    setSocket( createNewSocket(), type );
}

/*!
    Destroys the socket device and closes the socket if it is open.
*/
00210 Q3SocketDevice::~Q3SocketDevice()
{
    close();
    delete d;
    d = 0;
#if defined(Q3SOCKETDEVICE_DEBUG)
    qDebug( "Q3SocketDevice: Destroyed Q3SocketDevice %p", this );
#endif
}


/*!
    Returns true if this is a valid socket; otherwise returns false.

    \sa socket()
*/
00226 bool Q3SocketDevice::isValid() const
{
    return fd != -1;
}


/*!
    \fn Type Q3SocketDevice::type() const

    Returns the socket type which is either Q3SocketDevice::Stream
    or Q3SocketDevice::Datagram.

    \sa socket()
*/
00240 Q3SocketDevice::Type Q3SocketDevice::type() const
{
    return t;
}

/*!
    Returns the socket's protocol family, which is one of \c Unknown, \c IPv4,
    or \c IPv6.

    Q3SocketDevice either creates a socket with a well known protocol family or
    it uses an already existing socket. In the first case, this function
    returns the protocol family it was constructed with. In the second case, it
    tries to determine the protocol family of the socket; if this fails, it
    returns \c Unknown.

    \sa Protocol setSocket()
*/
00257 Q3SocketDevice::Protocol Q3SocketDevice::protocol() const
{
    if ( d->protocol == Unknown )
      d->protocol = getProtocol();
    return d->protocol;
}

/*!
    Returns the socket number, or -1 if it is an invalid socket.

    \sa isValid(), type()
*/
00269 int Q3SocketDevice::socket() const
{
    return fd;
}


/*!
    Sets the socket device to operate on the existing socket \a
    socket.

    The \a type argument must match the actual socket type; use \c
    Q3SocketDevice::Stream for a reliable, connection-oriented TCP
    socket, or Q3SocketDevice::Datagram for an unreliable,
    connectionless UDP socket.

    Any existing socket is closed.

    \sa isValid(), close()
*/
00288 void Q3SocketDevice::setSocket( int socket, Type type )
{
    if ( fd != -1 )                 // close any open socket
      close();
#if defined(Q3SOCKETDEVICE_DEBUG)
    qDebug( "Q3SocketDevice::setSocket: socket %x, type %d", socket, type );
#endif
    t = type;
    fd = socket;
    d->protocol = Unknown;
    e = NoError;
    resetStatus();
    open( ReadWrite );
    fetchConnectionParameters();
}


/*!
    Opens the socket using the specified QIODevice file \a mode. This
    function is called from the Q3SocketDevice constructors and from
    the setSocket() function. You should not call it yourself.

    \sa close()
*/
00312 bool Q3SocketDevice::open( OpenMode mode )
{
    if ( isOpen() || !isValid() )
      return false;
#if defined(Q3SOCKETDEVICE_DEBUG)
    qDebug( "Q3SocketDevice::open: mode %x", mode );
#endif
    setOpenMode( (mode & ReadWrite) | Unbuffered );
    return true;
}

/*!
    \fn bool Q3SocketDevice::open(int mode)
    \overload
*/
/*!
    The current Q3SocketDevice implementation does not buffer at all,
    so this is a no-op.
*/
00331 bool Q3SocketDevice::flush()
{
    return true;
}


/*!
    \reimp

    The size is meaningless for a socket, therefore this function returns 0.
*/
00342 QIODevice::Offset Q3SocketDevice::size() const
{
    return 0;
}


/*!
    The read/write index is meaningless for a socket, therefore this
    function returns 0.
*/
00352 QIODevice::Offset Q3SocketDevice::at() const
{
    return 0;
}


/*!
    The read/write index is meaningless for a socket, therefore this
    function does nothing and returns true.

    The \a offset parameter is ignored.
*/
00364 bool Q3SocketDevice::at( Offset /* offset */ )
{
    return true;
}


/*!
    \reimp

    Returns true if no data is currently available at the socket;
    otherwise returns false.
*/
00376 bool Q3SocketDevice::atEnd() const
{
    return bytesAvailable() <= 0;
}

/*!
    Returns true if the address of this socket can be used by other
    sockets at the same time, and false if this socket claims
    exclusive ownership.

    \sa setAddressReusable()
*/
00388 bool Q3SocketDevice::addressReusable() const
{
    return option( ReuseAddress );
}


/*!
    Sets the address of this socket to be usable by other sockets too
    if \a enable is true, and to be used exclusively by this socket if
    \a enable is false.

    When a socket is reusable, other sockets can use the same port
    number (and IP address), which is generally useful. Of course
    other sockets cannot use the same
    (address,port,peer-address,peer-port) 4-tuple as this socket, so
    there is no risk of confusing the two TCP connections.

    \sa addressReusable()
*/
00407 void Q3SocketDevice::setAddressReusable( bool enable )
{
    setOption( ReuseAddress, enable );
}


/*!
    Returns the size of the operating system receive buffer.

    \sa setReceiveBufferSize()
*/
00418 int Q3SocketDevice::receiveBufferSize() const
{
    return option( ReceiveBuffer );
}


/*!
    Sets the size of the operating system receive buffer to \a size.

    The operating system receive buffer size effectively limits two
    things: how much data can be in transit at any one moment, and how
    much data can be received in one iteration of the main event loop.

    The default is operating system-dependent. A socket that receives
    large amounts of data is probably best with a buffer size of
    49152.
*/
00435 void Q3SocketDevice::setReceiveBufferSize( uint size )
{
    setOption( ReceiveBuffer, size );
}


/*!
    Returns the size of the operating system send buffer.

    \sa setSendBufferSize()
*/
00446 int Q3SocketDevice::sendBufferSize() const
{
    return option( SendBuffer );
}


/*!
    Sets the size of the operating system send buffer to \a size.

    The operating system send buffer size effectively limits how much
    data can be in transit at any one moment.

    The default is operating system-dependent. A socket that sends
    large amounts of data is probably best with a buffer size of
    49152.
*/
00462 void Q3SocketDevice::setSendBufferSize( uint size )
{
    setOption( SendBuffer, size );
}


/*!
    Returns the port number of this socket device. This may be 0 for a
    while, but is set to something sensible as soon as a sensible
    value is available.

    Note that Qt always uses native byte order, i.e. 67 is 67 in Qt;
    there is no need to call htons().
*/
00476 quint16 Q3SocketDevice::port() const
{
    return p;
}


/*!
    Returns the address of this socket device. This may be 0.0.0.0 for
    a while, but is set to something sensible as soon as a sensible
    value is available.
*/
00487 QHostAddress Q3SocketDevice::address() const
{
    return a;
}


/*!
    Returns the first error seen.
*/
00496 Q3SocketDevice::Error Q3SocketDevice::error() const
{
    return e;
}


/*!
    Allows subclasses to set the error state to \a err.
*/
00505 void Q3SocketDevice::setError( Error err )
{
    e = err;
}

/*! \fn Q3SocketDevice::readBlock(char *data, Q_ULONG maxlen)

    Reads \a maxlen bytes from the socket into \a data and returns the
    number of bytes read. Returns -1 if an error occurred. Returning 0
    is not an error. For Stream sockets, 0 is returned when the remote
    host closes the connection. For Datagram sockets, 0 is a valid
    datagram size.
*/

/*! \fn Q3SocketDevice::writeBlock(const char *data, Q_ULONG len)

    Writes \a len bytes to the socket from \a data and returns the
    number of bytes written. Returns -1 if an error occurred.

    This is used for Q3SocketDevice::Stream sockets.
*/

/*!
    \fn bool Q3SocketDevice::isSequential() const
    \internal
*/
#endif //QT_NO_NETWORK

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