MirOS Manual: IO::Socket(3p)


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

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

     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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