1/*	$NetBSD: netof.c,v 1.5 2020/05/25 20:47:24 christos Exp $	*/
2
3/*
4 * netof - return the net address part of an ip address in a sockaddr_storage structure
5 *         (zero out host part)
6 */
7#include <config.h>
8#include <stdio.h>
9#include <syslog.h>
10
11#include "ntp_fp.h"
12#include "ntp_net.h"
13#include "ntp_stdlib.h"
14#include "ntp.h"
15
16sockaddr_u *
17netof(
18	sockaddr_u *hostaddr
19	)
20{
21	static sockaddr_u	netofbuf[8];
22	static int		next_netofbuf;
23	u_int32			netnum;
24	sockaddr_u *		netaddr;
25
26	netaddr = &netofbuf[next_netofbuf];
27	next_netofbuf = (next_netofbuf + 1) % COUNTOF(netofbuf);
28
29	memcpy(netaddr, hostaddr, sizeof(*netaddr));
30
31	if (IS_IPV4(netaddr)) {
32		netnum = SRCADR(netaddr);
33
34		/*
35		 * We live in a modern CIDR world where the basement nets, which
36		 * used to be class A, are now probably associated with each
37		 * host address. So, for class-A nets, all bits are significant.
38		 */
39		if (IN_CLASSC(netnum))
40			netnum &= IN_CLASSC_NET;
41		else if (IN_CLASSB(netnum))
42			netnum &= IN_CLASSB_NET;
43
44		SET_ADDR4(netaddr, netnum);
45
46	} else if (IS_IPV6(netaddr))
47		/* assume the typical /64 subnet size */
48		zero_mem(&NSRCADR6(netaddr)[8], 8);
49#ifdef DEBUG
50	else {
51		msyslog(LOG_ERR, "netof unknown AF %d", AF(netaddr));
52		exit(1);
53	}
54#endif
55
56	return netaddr;
57}
58