QSocketDevice(3qt)QSocketDevice(3qt)NAMEQSocketDevice - Platform-independent low-level socket API
#include <qsocketdevice.h>
Inherits QIODevice.
Public Members
enum Type { Stream, Datagram }
QSocketDevice ( Type type = Stream )
QSocketDevice ( int socket, Type type )
virtual ~QSocketDevice ()
bool isValid () const
Type type () const
int socket () const
virtual void setSocket ( int socket, Type type )
bool blocking () const
virtual void setBlocking ( bool )
bool addressReusable () const
virtual void setAddressReusable ( bool )
int receiveBufferSize () const
virtual void setReceiveBufferSize ( uint )
int sendBufferSize () const
virtual void setSendBufferSize ( uint )
virtual bool connect ( const QHostAddress &, Q_UINT16 )
virtual bool bind ( const QHostAddress &, Q_UINT16 )
virtual bool listen ( int backlog )
virtual int accept ()
int bytesAvailable () const
int waitForMore ( int msecs ) const
virtual int readBlock ( char * data, uint maxlen )
virtual int writeBlock ( const char * data, uint len )
virtual int writeBlock ( const char * data, uint len,
const QHostAddress & host, Q_UINT16 port )
Q_UINT16 port () const
Q_UINT16 peerPort () const
QHostAddress address () const
QHostAddress peerAddress () const
enum Error { NoError, AlreadyBound, Inaccessible,
NoResources, Bug, Impossible, NoFiles,
ConnectionRefused, NetworkFailure, UnknownError }
Error error () const
Protected Members
void setError ( Error err )
DESCRIPTION
The QSocketDevice class provides a platform-independent
low-level socket API.
This class is not really meant for use outside Qt. It can
be used to achieve some things that QSocket does not
provide, but it's not particularly easy to understand or
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QSocketDevice(3qt)QSocketDevice(3qt)
use.
The basic purpose of the class is to provide a QIODevice
that works on sockets, wrapped in a platform-independent
API.
See also QSocket, QSocketNotifier and QHostAddress.
Member Type Documentation
QSocketDevice::Error
This enum type describes the error states of
QSocketDevice. At present these errors are defined:
NoError - all is fine.
AlreadyBound - bind() said so.
Inaccessible - the operating system or firewall prohibits
something.
NoResources - the operating system ran out of something.
Bug - there seems to be a bug in QSocketDevice.
Impossible - the impossible happened, usually because you
confused QSocketDevice horribly. Simple example:
::close( sd->socket() );
sd->writeBlock( someData, 42 );
The libc ::close() closes the socket, but
QSocketDevice is not aware of that. So when you
call writeBlock(), the impossible happens.
NoFiles - the operating system will not let QSocketDevice
open another file.
ConnectionRefused - a connection attempt was rejected by
the peer.
NetworkFailure - there is a network failure between this
host and... and whatever.
UnknownError - the operating system reacted in a way that
the Qt developers did not foresee.
QSocketDevice::Type
This enum type describes the type of the socket:
Stream - a stream socket
Datagram - a datagram socket
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QSocketDevice(3qt)QSocketDevice(3qt)MEMBER FUNCTION DOCUMENTATIONQSocketDevice::QSocketDevice ( Type type = Stream )
Creates a QSocketDevice object for a stream or datagram
socket.
The type argument must be either QSocketDevice::Stream for
a reliable, connection-oriented TCP socket, or
QSocketDevice::Datagram for an unreliable UDP socket.
See also blocking().
QSocketDevice::QSocketDevice ( int socket, Type type )
Creates a QSocketDevice object for an existing socket.
The type argument must match the actual socket type;
QSocketDevice::Stream for a reliable, connection-oriented
TCP socket, or QSocketDevice::Datagram for an unreliable,
connectionless UDP socket.
QSocketDevice::~QSocketDevice () [virtual]
Destroys the socket device and closes the socket if it is
open.
int QSocketDevice::accept () [virtual]
Extracts the first connection from the queue of pending
connections for this socket and returns a new socket
identifier. Returns -1 if the operation failed.
See also bind() and listen().
QHostAddress QSocketDevice::address () const
Returns the address of this socket device. This may be
0.0.0.0 for a while, but is set to something sensible when
there is a sensible value it can have.
bool QSocketDevice::addressReusable () const
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.
See also setAddressReusable().
bool QSocketDevice::at ( int ) [virtual]
Reimplemented for internal reasons; the API is not
affected.
The read/write index is meaningless for a socket,
therefore this function does nothing and returns TRUE.
Reimplemented from QIODevice.
int QSocketDevice::at () const [virtual]
Reimplemented for internal reasons; the API is not
affected.
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QSocketDevice(3qt)QSocketDevice(3qt)
The read/write index is meaningless for a socket,
therefore this function returns 0.
Reimplemented from QIODevice.
bool QSocketDevice::atEnd () const [virtual]
Reimplemented for internal reasons; the API is not
affected.
The read/write index is meaningless for a socket,
therefore this always returns FALSE.
Reimplemented from QIODevice.
bool QSocketDevice::bind ( const QHostAddress & address, Q_UINT16
port ) [virtual]
Assigns a name to an unnamed socket. If the operation
succeeds, bind() returns TRUE. Otherwise, it returns FALSE
without changing what port() and address() return.
bind() is used by servers for setting up incoming
connections. Call bind() before listen().
bool QSocketDevice::blocking () const
Returns TRUE if the socket is in blocking mode, or FALSE
if it is in nonblocking mode or if the socket is invalid.
Note that this function does not set error().
Warning: On Windows, this function always returns TRUE
since the ioctlsocket() function is broken.
See also setBlocking() and isValid().
int QSocketDevice::bytesAvailable () const
Returns the number of bytes available for reading, or -1
if an error occurred.
Warning: On Microsoft Windows, we use the ioctlsocket()
function to determine the number of bytes queued on the
socket. According to Microsoft (KB Q125486), ioctlsocket()
sometimes return an incorrect number. The only safe way to
determine the amount of data on the socket is to read it
using readBlock(). QSocket has workarounds to deal with
this problem.
void QSocketDevice::close () [virtual]
Reimplemented for internal reasons; the API is not
affected.
Closes the socket and sets the socket identifier to -1
(invalid).
(This function ignores errors; if there are any then a
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QSocketDevice(3qt)QSocketDevice(3qt)
file descriptor leakage might result. As far as we know,
the only error that can arise is EBADF, and that would of
course not cause leakage. There may be OS-specfic errors
that we haven't come across, however.)
See also open().
Reimplemented from QIODevice.
bool QSocketDevice::connect ( const QHostAddress & addr, Q_UINT16
port ) [virtual]
Connects to the IP address and port specified by addr.
Returns TRUE if it establishes a connection, and FALSE if
not. error() explains why.
Note that error() commonly returns NoError for non-
blocking sockets; this just means that you can call
connect() again in a little while and it'll probably
succeed.
QSocketDevice::Error QSocketDevice::error() const
Returns the first error seen.
void QSocketDevice::flush () [virtual]
Reimplemented for internal reasons; the API is not
affected.
QSocketDevice does not buffer at all, so this is a no-op.
Reimplemented from QIODevice.
int QSocketDevice::getch () [virtual]
Reimplemented for internal reasons; the API is not
affected.
Warning: getch() is implemented as a one-byte readBlock(),
so it may be very slow if you call it more than a few
times.
See also putch() and readBlock().
Reimplemented from QIODevice.
bool QSocketDevice::isValid () const
Returns TRUE if this is a valid socket or FALSE if it is
an invalid socket. This is actually a shortcut for
socket() == -1.
See also socket().
bool QSocketDevice::listen ( int backlog ) [virtual]
Specifies how many pending connections a server socket can
have. Returns TRUE if the operation was successful,
otherwise FALSE.
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QSocketDevice(3qt)QSocketDevice(3qt)
The listen() call only applies to sockets where type() is
Stream, not Datagram sockets. listen() must not be called
before bind() or after accept(). It is common to use a
backlog value of 50 on most Unix systems.
See also bind() and accept().
bool QSocketDevice::open ( int mode ) [virtual]
Reimplemented for internal reasons; the API is not
affected.
Opens the socket using the specified QIODevice file mode.
This function is called from the QSocketDevice
constructors and from the setSocket() function. You should
not call it yourself.
See also close().
Reimplemented from QIODevice.
QHostAddress QSocketDevice::peerAddress () const
Returns the address of the port this socket device is
connected to. This may be 0.0.0.0 for a while, but is set
to something sensible when there is a sensible value it
can have.
Note that for Datagram sockets, this is the source address
of the last packet received.
Q_UINT16 QSocketDevice::peerPort () const
Returns the port number of the port this socket device is
connected to. This may be 0 for a while, but is set to
something sensible when there is a sensible value it can
have.
Note that for Datagram sockets, this is the source port of
the last packet received.
Q_UINT16 QSocketDevice::port () const
Returns the port number of this socket device. This may be
0 for a while, but is set to something sensible when there
is a sensible value it can have.
int QSocketDevice::putch ( int ch ) [virtual]
Reimplemented for internal reasons; the API is not
affected.
Warning: putch() is implemented as a one-byte
writeBlock(), so it may be very slow if you call it more
than a few times.
See also getch().
Reimplemented from QIODevice.
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QSocketDevice(3qt)QSocketDevice(3qt)int QSocketDevice::readBlock ( char * data, uint maxlen )
[virtual]
Reads max maxlen bytes from the socket into data and
returns the number of bytes read. Returns -1 if an error
occurred.
Reimplemented from QIODevice.
int QSocketDevice::receiveBufferSize () const
Returns the size of the OS receive buffer.
See also setReceiveBufferSize().
int QSocketDevice::sendBufferSize () const
Returns the size of the OS send buffer.
See also setSendBufferSize().
void QSocketDevice::setAddressReusable ( bool enable ) [virtual]
Sets the address of this socket to be usable by other
sockets too if enable is TRUE, and to be used exclusively
by this socket if enable is FALSE.
When a socket is reusable, other sockets can use the same
port number (and IP address), which is in general good. 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.
See also addressReusable().
void QSocketDevice::setBlocking ( bool enable ) [virtual]
Makes the socket blocking if enable is TRUE or nonblocking
if enable is FALSE.
Sockets are blocking by default, but we recommend using
nonblocking socket operations, especially for GUI programs
that need to be responsive.
Warning: On Windows, this function does nothing since the
ioctlsocket() function is broken.
Whenever you use a QSocketNotifier on Windows, the socket
is immediately made nonblocking.
See also blocking() and isValid().
void QSocketDevice::setError ( Error err ) [protected]
Allows subclasses to set the error state.
void QSocketDevice::setReceiveBufferSize ( uint size ) [virtual]
Sets the size of the OS receive buffer to size.
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The OS 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 OS-dependent. A socket that receives large
amounts of data is probably best off with a buffer size of
49152.
void QSocketDevice::setSendBufferSize ( uint size ) [virtual]
Sets the size of the OS send buffer to size.
The OS send buffer size effectively limits how much data
can be in transit at any one moment.
The default is OS-dependent. A socket that sends large
amounts of data is probably best off with a buffer size of
49152.
void QSocketDevice::setSocket ( int socket, Type type )
Sets an existing socket.
The type argument must match the actual socket type;
QSocketDevice::Stream for a reliable, connection-oriented
TCP socket, or QSocketDevice::Datagram for an unreliable,
connectionless UDP socket.
Any existing socket is closed.
See also isValid() and close().
uint QSocketDevice::size () const [virtual]
Reimplemented for internal reasons; the API is not
affected.
The size is meaningless for a socket, therefore this
function returns 0.
Reimplemented from QIODevice.
int QSocketDevice::socket () const
Returns the socket number, or -1 if it is an invalid
socket.
See also isValid() and type().
Type QSocketDevice::type () const
Returns the socket type; QSocketDevice::Stream for a
reliable, connection-oriented TCP socket, or
QSocketDevice::Datagram for an unreliable UDP socket.
See also socket().
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QSocketDevice(3qt)QSocketDevice(3qt)int QSocketDevice::ungetch ( int ) [virtual]
Reimplemented for internal reasons; the API is not
affected.
This implementation of ungetch returns -1 (error). A
socket is a sequential device and does not allow any
ungetch operation.
Reimplemented from QIODevice.
int QSocketDevice::waitForMore ( int msecs ) const
Wait up to msecs milliseconds for more data to be
available. If msecs is -1 the call will block
indefinitely.
This is a blocking call and should be avoided in event
driven applications.
Returns the number of bytes available for reading, or -1
if an error occurred.
See also bytesAvailable().
int QSocketDevice::writeBlock ( const char * data, uint len )
[virtual]
Writes len bytes to the socket from data and returns the
number of bytes written. Returns -1 if an error occurred.
This is used for QSocketDevice::Stream sockets.
Reimplemented from QIODevice.
int QSocketDevice::writeBlock ( const char * data, uint len,
const QHostAddress & host, Q_UINT16 port ) [virtual]
Writes len bytes to the socket from data and returns the
number of bytes written. Returns -1 if an error occurred.
This is used for QSocketDevice::Datagram sockets. You have
to specify the host and port of the destination of the
data.
SEE ALSO
http://doc.trolltech.com/qsocketdevice.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2001 Trolltech AS,
http://www.trolltech.com. See the license file included
in the distribution for a complete license statement.
AUTHOR
Generated automatically from the source code.
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QSocketDevice(3qt)QSocketDevice(3qt)BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports
make our job much simpler. Thank you.
In case of content or formattting problems with this
manual page, please report them to qt-bugs@trolltech.com.
Please include the name of the manual page
(qsocketdevice.3qt) and the Qt version (2.3.1).
Trolltech AS 13 June 2001 10
