NAME¶
IO::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.
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 <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 redistribute it as long as you
retain the correct attribution.