The code fragment is:
# this is called to connect to remote host
sub connect {
  my $pack = shift;
  my ($host,$port) = @_;

  my $sock = IO::Socket::INET->new(Proto => 'tcp',
                                   Type  => SOCK_STREAM);
  return unless $sock;
  $sock->blocking(0);
  my $addr = sockaddr_in($port,inet_aton($host));
  my $result = $sock->connect($addr);
  return $sock if $result;  # return the socket if connected immediately
  return $sock if $! == EINPROGRESS;  # or if it's in progress
  return;                             # return undef on other errors
}