IO::Socket::INET - Online Linux Manual Page

Section : 3pm
Updated : 2023-01-19
Source : perl v5.36.0
Note : Perl Programmers Reference Guide

NAME

IO::Socket::INET − Object interface for AF_INET domain sockets

SYNOPSIS

​    use IO::Socket::INET;

DESCRIPTION

IO::Socket::INET

provides an object interface to creating and using sockets in the AF_INET domain. It is built upon the IO::Socket interface and inherits all the methods defined by IO::Socket.

CONSTRUCTOR

new (

[

ARGS

]

)

Creates an IO::Socket::INET

object, which is a reference to a newly created symbol (see the

Symbol

package).

new

optionally takes arguments, these arguments are in key-value pairs. In addition to the key-value pairs accepted by IO::Socket,

IO::Socket::INET

provides.

​ PeerAddr    Remote host address          <hostname>[:<port>]
​ PeerHost    Synonym for PeerAddr
​ PeerPort    Remote port or service       <service>[(<no>)] | <no>
​ LocalAddr   Local host bind address      hostname[:port]
​ LocalHost   Synonym for LocalAddr
​ LocalPort   Local host bind port         <service>[(<no>)] | <no>
​ Proto       Protocol name (or number)    "tcp" | "udp" | ...
​ Type        Socket type              SOCK_STREAM | SOCK_DGRAM | ...
​ Listen      Queue size for listen
​ ReuseAddr   Set SO_REUSEADDR before binding
​ Reuse       Set SO_REUSEADDR before binding (deprecated,
​                                              prefer ReuseAddr)
​ ReusePort   Set SO_REUSEPORT before binding
​ Broadcast   Set SO_BROADCAST before binding
​ Timeout     Timeout value for various operations
​ MultiHomed  Try all addresses for multi−homed hosts
​ Blocking    Determine if connection will be blocking mode

Listen

is defined then a listen socket is created, else if the socket type, which is derived from the protocol, is SOCK_STREAM then

connect(

)

is called. If the

Listen

argument is given, but false, the queue size will be set to 5. Although it is not illegal, the use of

MultiHomed

on a socket which is in non-blocking mode is of little use. This is because the first connect will never fail with a timeout as the connect call will not block. The

PeerAddr

can be a hostname or the IP-address on the ‟xx.xx.xx.xx” form. The

PeerPort

can be a number or a symbolic service name. The service name might be followed by a number in parenthesis which is used if the service is not known by the system. The

PeerPort

specification can also be embedded in the

PeerAddr

by preceding it with a ‟:”. If

Proto

is not given and you specify a symbolic

PeerPort

port, then the constructor will try to derive

Proto

from the service name. As a last resort

Proto

‟tcp” is assumed. The

Type

parameter will be deduced from

Proto

if not specified. If the constructor is only passed a single argument, it is assumed to be a

PeerAddr

specification. If

Blocking

is set to 0, the connection will be in nonblocking mode. If not specified it defaults to 1 (blocking mode). Examples:

​   $sock = IO::Socket::INET−>new(PeerAddr => 'www.perl.org',
​                                 PeerPort => 'http(80)',
​                                 Proto    => 'tcp');
​
​   $sock = IO::Socket::INET−>new(PeerAddr => 'localhost:smtp(25)');
​
​   $sock = IO::Socket::INET−>new(Listen    => 5,
​                                 LocalAddr => 'localhost',
​                                 LocalPort => 9000,
​                                 Proto     => 'tcp');
​
​   $sock = IO::Socket::INET−>new('127.0.0.1:25');
​
​   $sock = IO::Socket::INET−>new(
​                           PeerPort  => 9999,
​                           PeerAddr  => inet_ntoa(INADDR_BROADCAST),
​                           Proto     => 'udp',
​                           LocalAddr => 'localhost',
​                           Broadcast => 1 ) 
​                       or die "Can't bind : $IO::Socket::errstr\n";

If the constructor fails it will return

undef

and set the

$IO::Socket::errstr

package variable to contain an error message.

​    $sock = IO::Socket::INET−>new(...)
​        or die "Cannot create socket − $IO::Socket::errstr\n";

For legacy reasons the error message is also set into the global

$@

variable, and you may still find older code which looks here instead.

​    $sock = IO::Socket::INET−>new(...)
​        or die "Cannot create socket − $@\n";

METHODS

sockaddr (

)

Return the address part of the sockaddr structure for the socket

sockport (

)

Return the port number that the socket is using on the local host

sockhost (

)

Return the address part of the sockaddr structure for the socket in a text form xx.xx.xx.xx

peeraddr (

)

Return the address part of the sockaddr structure for the socket on the peer host

peerport (

)

Return the port number for the socket on the peer host.

peerhost (

)

Return the address part of the sockaddr structure for the socket on the peer host in a text form xx.xx.xx.xx