IO::Socket(3p) Perl Programmers Reference Guide IO::Socket(3p)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" option-
ally 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 argu-
ments 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 fol-
lowing 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
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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 ineffi-
cient. 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 sockat-
mark() 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.
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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 get-
sockopt is called, otherwise setsockopt is called.
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 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.
SEE ALSO
Socket, IO::Handle, IO::Socket::INET, IO::Socket::UNIX
AUTHOR
Graham Barr. atmark() by Lincoln Stein. Currently main-
tained by the Perl Porters. Please report all bugs to
<perl5-porters@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 redistri-
bute it as long as you retain the correct attribution.
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