IO::Socket(3perl) Perl Programmers Reference Guide IO::Socket(3perl)NAMEIO::Socket - Object interface to socket communications
SYNOPSIS
use IO::Socket;
DESCRIPTION
"IO::Socket" provides an object interface to creating and using
sockets. It is built upon the IO::Handle interface and inherits all the
methods defined by IO::Handle.
"IO::Socket" only defines methods for those operations which are common
to all types of socket. Operations which are specified to a socket in a
particular domain have methods defined in sub classes of "IO::Socket"
"IO::Socket" will export all functions (and constants) defined by
Socket.
CONSTRUCTOR
new ( [ARGS] )
Creates an "IO::Socket", which is a reference to a newly created
symbol (see the "Symbol" package). "new" optionally takes
arguments, these arguments are in key-value pairs. "new" only
looks for one key "Domain" which tells new which domain the socket
will be in. All other arguments will be passed to the configuration
method of the package for that domain, See below.
NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE
As of VERSION 1.18 all IO::Socket objects have autoflush turned on
by default. This was not the case with earlier releases.
NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE NOTE
METHODS
See perlfunc for complete descriptions of each of the following
supported "IO::Socket" methods, which are just front ends for the
corresponding built-in functions:
socket
socketpair
bind
listen
accept
send
recv
peername (getpeername)
sockname (getsockname)
shutdown
Some methods take slightly different arguments to those defined in
perlfunc in attempt to make the interface more flexible. These are
accept([PKG])
perform the system call "accept" on the socket and return a new
object. The new object will be created in the same class as the
listen socket, unless "PKG" is specified. This object can be used
to communicate with the client that was trying to connect.
In a scalar context the new socket is returned, or undef upon
failure. In a list context a two-element array is returned
containing the new socket and the peer address; the list will be
empty upon failure.
The timeout in the [PKG] can be specified as zero to effect a
"poll", but you shouldn't do that because a new IO::Select object
will be created behind the scenes just to do the single poll. This
is horrendously inefficient. Use rather true select() with a zero
timeout on the handle, or non-blocking IO.
socketpair(DOMAIN, TYPE, PROTOCOL)
Call "socketpair" and return a list of two sockets created, or an
empty list on failure.
Additional methods that are provided are:
atmark
True if the socket is currently positioned at the urgent data mark,
false otherwise.
use IO::Socket;
my $sock = IO::Socket::INET->new('some_server');
$sock->read($data, 1024) until $sock->atmark;
Note: this is a reasonably new addition to the family of socket
functions, so all systems may not support this yet. If it is
unsupported by the system, an attempt to use this method will abort
the program.
The atmark() functionality is also exportable as sockatmark()
function:
use IO::Socket 'sockatmark';
This allows for a more traditional use of sockatmark() as a
procedural socket function. If your system does not support
sockatmark(), the "use" declaration will fail at compile time.
connected
If the socket is in a connected state the peer address is returned.
If the socket is not in a connected state then undef will be
returned.
protocol
Returns the numerical number for the protocol being used on the
socket, if known. If the protocol is unknown, as with an AF_UNIX
socket, zero is returned.
sockdomain
Returns the numerical number for the socket domain type. For
example, for an AF_INET socket the value of &AF_INET will be
returned.
sockopt(OPT [, VAL])
Unified method to both set and get options in the SOL_SOCKET level.
If called with one argument then getsockopt is called, otherwise
setsockopt is called.
getsockopt(LEVEL, OPT)
Get option associated with the socket. Other levels than SOL_SOCKET
may be specified here.
setsockopt(LEVEL, OPT, VAL)
Set option associated with the socket. Other levels than SOL_SOCKET
may be specified here.
socktype
Returns the numerical number for the socket type. For example, for
a SOCK_STREAM socket the value of &SOCK_STREAM will be returned.
timeout([VAL])
Set or get the timeout value (in seconds) associated with this
socket. If called without any arguments then the current setting
is returned. If called with an argument the current setting is
changed and the previous value returned.
LIMITATIONS
On some systems, for an IO::Socket object created with new_from_fd(),
or created with accept() from such an object, the protocol(),
sockdomain() and socktype() methods may return undef.
SEE ALSO
Socket, IO::Handle, IO::Socket::INET, IO::Socket::UNIX
AUTHOR
Graham Barr. atmark() by Lincoln Stein. Currently maintained by the
Perl Porters. Please report all bugs to <perlbug@perl.org>.
COPYRIGHT
Copyright (c) 1997-8 Graham Barr <gbarr@pobox.com>. All rights
reserved. This program is free software; you can redistribute it
and/or modify it under the same terms as Perl itself.
The atmark() implementation: Copyright 2001, Lincoln Stein
<lstein@cshl.org>. This module is distributed under the same terms as
Perl itself. Feel free to use, modify and redistribute it as long as
you retain the correct attribution.
perl v5.18.2 2014-01-06 IO::Socket(3perl)
