Interesting problem.
#!/usr/bin/perl -w
use strict;
sub output {
my( $nLow, $cBits )= @_;
my $ipLow= join ".", unpack "C*", pack "N", $nLow;
print " $ipLow/$cBits\n";
}
while( <DATA> ) {
my( $ipMin, $ipMax )= split " ", $_;
print "$ipMin - $ipMax:\n";
my $nMin= unpack "N", pack "C*", split /\./, $ipMin;
my $nMax= unpack "N", pack "C*", split /\./, $ipMax;
my $bitsMin= 1;
my $maskMin= 1;
my $bitsMax= 1;
my $maskMax= 1;
while( 1 ) {
while( 0 == ( $nMin & $maskMin ) ) {
( $maskMin <<= 1 ) |= 1;
$bitsMin++;
}
last if $nMax < ( $nMin | $maskMin );
output( $nMin, $bitsMin-1 );
( $nMin |= $maskMin ) += 1;
}
while( 1 ) {
while( $maskMax == ( $nMax & $maskMax ) ) {
( $maskMax <<= 1 ) |= 1;
$bitsMax++;
}
$nMax &= ~$maskMax;
last if $nMax < $nMin;
output( $nMax--, $bitsMax-1 );
}
}
__END__
192.168.0.0 192.168.255.255
192.168.1.17 192.168.112.26
produces:
192.168.0.0 - 192.168.255.255:
192.168.0.0/16
192.168.1.17 - 192.168.112.26:
192.168.1.17/0
192.168.1.18/1
192.168.1.20/2
192.168.1.24/3
192.168.1.32/5
192.168.1.64/6
192.168.1.128/7
192.168.2.0/9
192.168.4.0/10
192.168.8.0/11
192.168.16.0/12
192.168.32.0/13
192.168.112.26/0
192.168.112.24/1
192.168.112.16/3
192.168.112.0/4
192.168.96.0/12
192.168.64.0/13
Sorry about the last half being output in the reverse order.
I haven't tested it extensively, but it feels right and works for the cases I did test.
-
tye
(but my friends call me "Tye")