|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.
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
Additional methods that are provided 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 shouldnt 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.
atmark True if the socket is currently positioned at the urgent data mark, false otherwise.
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:
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, undef is returned.
Note that connected() considers a half-open TCP socket to be in a connected state. Specifically, connected() does not distinguish between the <B>ESTABLISHEDB> and <B>CLOSE-WAITB> TCP states; it returns the peer address, rather than undef, in either case. Thus, in general, connected() cannot be used to reliably learn whether the peer has initiated a graceful shutdown because in most cases (see below) the local TCP state machine remains in <B>CLOSE-WAITB> until the local application calls shutdown() or close(); only at that point does connected() return undef.
The in most cases hedge is because local TCP state machine behavior may depend on the peers socket options. In particular, if the peer socket has SO_LINGER enabled with a zero timeout, then the peers close() will generate a RST segment, upon receipt of which the local TCP transitions immediately to <B>CLOSEDB>, and in that state, connected() will return undef.
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.
On some systems, for an IO::Socket object created with new_from_fd(), or created with accept() from such an object, the protocol(), sockdomain() and socktype() methods may return undef.
Socket, IO::Handle, IO::Socket::INET, IO::Socket::UNIX
Graham Barr. atmark() by Lincoln Stein. Currently maintained by the Perl Porters. Please report all bugs to <email@example.com>.
Copyright (c) 1997-8 Graham Barr <firstname.lastname@example.org>. 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 <email@example.com>. 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 v5.22.1||IO::SOCKET (3)||2015-10-17|