validateMask is a subroutine that takes a dotted-decimal IP mask (a.k.a. netmask) and checks to see if the mask is logical. Returns 1 on success, undef otherwise.

UPDATE: totally rewrote the thing under license from TIMTOWTDI. Instead of doing things in decimal, I convert the mask to the 32-bit string, then look to see if there is a zero followed by a one. Takes care of most identified concerns.

UPDATE 1: okay ... took out the Socket requirement ... THX to whomever pointed this out ...

UPDATE 2: Threw the $mask var back in ... can't remember why I started playing w/ that

sub validateMask {
  return                                # return undef if it's not com
+plete
    unless $_[0] =~/^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/;
  my $mask = unpack (
          "B32",
          pack( 
               "C4", 
               split ( /\./, $_[0] )
              )
         );

  return                                # return undef if we find an i
+nvalid
    if $mask =~ /01/;                   # mask ( a zero followed by a 
+one )
  return 1;                             # return 1 if everything is ok
+ay
}

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In reply to validateMask by idnopheq

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