TCP port check time out?

Massyn has asked for the wisdom of the Perl Monks concerning the following question:

#!/fellow/monks.pl

I have the following procedure that I use to determine if a TCP port is available. When it's up, it works fine, however, I found that when a link goes down, it takes a while to timeout, resulting in my script to sit and wait a long time before continuing. Is there any way I can force a timeout?

use IO::Socket;

sub check_port {
  my ($host,$port) = @_;

  $remote = IO::Socket::INET -> new (
             Proto => "tcp",
             PeerAddr => $host,
             PeerPort => $port
             ) ;
  if ($remote) {
    close $remote;
    return 1;
  }
  else {
    return 0;
  }
}
[download]

Thanks!

#!/massyn.pl The early worm gets caught by the bird.

Comment on TCP port check time out? Download Code

Replies are listed 'Best First'.
Re: TCP port check time out? by bronto (Priest) on Mar 12, 2003 at 10:31 UTC
Use `perldoc IO::Socket`: `timeout([VAL]) Set or get the timeout value associated with this socket. If called without any arguments then the cur- rent setting is returned. If called with an argument the current setting is changed and the previous value returned.` [download] Ciao! `--bronto` The very nature of Perl to be like natural language--inconsistant and full of dwim and special cases--makes it impossible to know it all without simply memorizing the documentation (which is not complete or totally correct anyway). --John M. Dlugosz	[reply] [d/l] [select]
Re: TCP port check time out? by Tomte (Priest) on Mar 12, 2003 at 10:34 UTC
First go for brontos tip. If that doesn't help/suit your needs, take a look at `perldoc -f alarm` and in `perldoc perlvar` search for `%SIG` regards, tomte Edit:I received downvotes for this node I'd like a cb-/msg or an answer on why. A quick glance, before I wrote this node, into IO/Socket.pm suggested that the timeout is implemented, as it should be, using the correct calls to the underlying OS, and not a brute-force approach like `alarm`. I wrote this tip, because there are circumstances where a socket timeout may just not work (mostly OS related, me thinks), but `alarm` will.	[reply]