Hi Kipp,
I'd say don't bother pack()ing. At the moment, I think the function pretty much
s**ks. use eval() instead. The following doesn't have that one-liner compactness of
the others, but it shows you what is going on. The bitwise & does a real cute little
trick with its operands, evaluating them in hex context or digit-by-digit (I can't
tell which, and the two may be functionally indistinguishable.) Therefore I got
results like 192 & 255 = 010 [the nine and five match on the 0 bit, no other digits
match any bits with their corresponding digit in the other number.
That doesn't quite get us there. Here is my approach:
#!/usr/bin/perl
my ($IP_String, $MaskString) = split(/ +/, $ARGV[0]);
@IP_Address = ExtractBytes($IP_String);
@Mask = ExtractBytes($MaskString);
@NetworkAddress = AND_MaskArray(4, \@IP_Address, \@Mask, $ARGV);
print
"$NetworkAddress[0]\.$NetworkAddress[1]\.$NetworkAddress[2]\.$NetworkAddress[3]";
sub ExtractBytes {
my $DottedString = $_[0];
@AddressBytes = split (/\./, $DottedString);
return @AddressBytes;
}
sub AND_MaskArray {
$limit = $_[0];
my @result;
for (my $i = 0; $i < $limit; $i++) {
$Temp = eval($IP_Address[$i]) & eval($Mask[$i]);
$result[$i] = $Temp;
}
return @result;
}
And will handle any kind of and-masking. I had it set up to do or-ing, too, then
dumped that part when I could concieve of no useful purpose for or-ing IPs. This will
also extract a classless IP subnet, or a host mask if the parameters are reversed.
E:\d_drive\perlStuff>andips.pl "192.168.0.102 255.255.0.0"
192.168.0.0
E:\d_drive\perlStuff>andips.pl "221.215.156.68 255.255.255.128"
221.215.156.0
E:\d_drive\perlStuff>andips.pl "221.215.156.168 255.255.255.128"
221.215.156.128
E:\d_drive\perlStuff>andips.pl "221.215.156.168 0.0.0.127"
Joseph
"Kipp, James" wrote:
> Happy Hollidays
>
> I want to bitwize AND 2 IP adr strings, not sure of how to pack() them to be
> able to AND them. before i start playing with pack,sprintf,socket,etc.. I
> was wondering if someone already had a way.
>
> Thanks
>
>
>
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