ntomask.c revision 170268 
1/*	$FreeBSD: head/contrib/ipfilter/lib/ntomask.c 170268 2007-06-04 02:54:36Z darrenr $	*/
2
3/*
4 * Copyright (C) 2002-2005 by Darren Reed.
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 *
8 * $Id: ntomask.c,v 1.6.2.1 2006/06/16 17:21:07 darrenr Exp $
9 */
10
11#include "ipf.h"
12
13int ntomask(v, nbits, ap)
14int v, nbits;
15u_32_t *ap;
16{
17	u_32_t mask;
18
19	if (nbits < 0)
20		return -1;
21
22	switch (v)
23	{
24	case 4 :
25		if (nbits > 32 || use_inet6 != 0)
26			return -1;
27		if (nbits == 0) {
28			mask = 0;
29		} else {
30			mask = 0xffffffff;
31			mask <<= (32 - nbits);
32		}
33		*ap = htonl(mask);
34		break;
35
36	case 6 :
37		if ((nbits > 128) || (use_inet6 == 0))
38			return -1;
39		fill6bits(nbits, ap);
40		break;
41
42	default :
43		return -1;
44	}
45	return 0;
46}
47