Bitwise operators operate on the "internal" bitstrings that represent numbers or strings, not on strings of 1s and 0s. The reason & and | seem to work is that their characters only differ by a bit. When you complement them, you get those weird characters.

Instead of unpacking to B, unpack to L (unsigned long), then do your operations. Then use the %032b format of printf to get the bitstring.

sub is_hostaddress {
        my $self = shift if ref($_[0]);
        my $ipaddr = shift;
        my $netmask = shift;

        return unless defined($ipaddr) && defined($netmask);

        my $binipaddr = unpack('L', pack('C4', split(/\./, $ipaddr)));
        my $binnetmask = unpack('L', pack('C4', split(/\./, $netmask))
+);
        my $result = $binipaddr & $binnetmask;
        my $result2 = $binipaddr | ~$binnetmask;

#        printf "%04x %04x, %04x %04x\n", $binipaddr, $binnetmask, $re
+sult, $result2;
#        printf "%032b\n%032b\n", $binipaddr, $binnetmask;
        printf "%032b\n%032b\n", $result, $result2;
}
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