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 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 "Sym-
           bol" 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 con-
           text 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 fail-
           ure.

       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 sys-
           tems 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 func-
           tion.  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.

       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 argu-
           ments 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 <>.

COPYRIGHT
       Copyright (c) 1997-8 Graham Barr <>. 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 <>.  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)