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Net::EmptyPort(3) User Contributed Perl Documentation Net::EmptyPort(3)

NAME

Net::EmptyPort - find a free TCP/UDP port

SYNOPSIS

    use Net::EmptyPort qw(empty_port check_port);
    # get a socket listening on a random free port
    my $socket = listen_socket();
    # get a random free port
    my $port = empty_port();
    # check if a port is already used
    if (check_port(5000)) {
        say "Port 5000 already in use";
    }

DESCRIPTION

Net::EmptyPort helps finding an empty TCP/UDP port.

METHODS

    my $socket = listen_socket();

Returns a socket listening on a free port.

The function recognizes the following keys in the hashref argument.

"host"
The address on which to listen. Default is 127.0.0.1.
"proto"
Name of the protocol. Default is "tcp". You can get an UDP socket by specifying "udp".
"empty_port($port, $proto)"
    my $port = empty_port();

Returns a port number that is NOT in use.

The function recognizes the following keys when given a hashref as the argument.

"host"
specifies the address on which the search should be performed. Default is 127.0.0.1.
"port"
Lower bound of the search for an empty port. If omitted, the function searches for an empty port within 49152..65535.

See <http://www.iana.org/assignments/port-numbers>

"proto"
Name of the protocol. Default is "tcp". You can find an empty UDP port by specifying "udp".

To maintain backwards compatibility, the function accepts scalar arguments as well. For example, you can also find an empty UDP port by specifying the protocol as the second parameter:

    my $port = empty_port(1024, 'udp');
    # use 49152..65535 range
    my $port = empty_port(undef, 'udp');
"check_port($port, $proto)"
    my $true_or_false = check_port(5000);

Checks if the given port is already in use. Returns true if it is in use (i.e. if the port is NOT free). Returns false if the port is free.

The function recognizes the following keys when given a hashref as the argument.

When UDP is specified as the protocol, the `check_port` function sends a probe UDP packet to the designated port to see if an ICMP error message is returned, which indicates that the port is unassigned. The port is assumed to be assigned, unless such response is observed within 0.1 seconds.

"host"
specifies the address on which the search should be performed. Default is 127.0.0.1.
"port"
specifies the port to check. This argument is mandatory.
"proto"
name of the protocol. Default is "tcp".

To maintain backwards compatibility, the function accepts scalar arguments as well in the form described above.

"wait_port($port, $max_wait)"
"wait_port($port, $max_wait, $proto)"
Waits until a particular port becomes ready to connect to. Returns true if the port becomes ready, or false if otherwise.

The function recognizes the following keys when given a hashref as the argument.

"host"
specifies the address on which the search should be performed. Default is 127.0.0.1.
"port"
specifies the port to check. This argument is mandatory.
"max_wait"
maximum seconds to wait for (default is 10 seconds). Pass a negative value to wait infinitely.
"proto"
name of the protocol. Default is "tcp".

To maintain backwards compatibility, the function accepts scalar arguments as well in the form described above.

Incompatible changes: Before 2.0, "wait_port($port:Int[, $sleep:Number, $retry:Int, $proto:String])" is a signature.

"can_bind($host, $port)"
"can_bind($host, $port, $proto)"
Checks if the application is capable of binding to given port.

AUTHOR

Tokuhiro Matsuno <tokuhirom@gmail.com>

THANKS TO

kazuhooku

dragon3

charsbar

Tatsuhiko Miyagawa

lestrrat

SEE ALSO

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

2019-10-09 perl v5.40.0