No need for eval to convert from binary: 

sub bin {
   return unpack('N', pack('B32', substr('0'x32 . $_[0], -32)));
}

$mask = bin('1'x$bits . '0'x(32-$bits));

[download]

No need for eval to create an IP mask: 

$mask = 0xFFFFFFFF << (32-$bits);

[download]

In reply to Re: String eval is cool by ikegami
in thread String eval is cool by DrHyde

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