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IO::Socket(3)          Perl Programmers Reference Guide          IO::Socket(3)



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 inter-
       face 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 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 maintained by the Perl Porters.  Please report all bugs to
       <perl5-portersATperl.org>.

COPYRIGHT
       Copyright (c) 1997-8 Graham Barr <gbarrATpobox.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 <lsteinATcshl.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 v5.8.8                       2001-09-21                     IO::Socket(3)