netof.c revision 290001 
1/*
2 * netof - return the net address part of an ip address in a sockaddr_storage structure
3 *         (zero out host part)
4 */
5#include <config.h>
6#include <stdio.h>
7#include <syslog.h>
8
9#include "ntp_fp.h"
10#include "ntp_net.h"
11#include "ntp_stdlib.h"
12#include "ntp.h"
13
14sockaddr_u *
15netof(
16	sockaddr_u *hostaddr
17	)
18{
19	static sockaddr_u	netofbuf[8];
20	static int		next_netofbuf;
21	u_int32			netnum;
22	sockaddr_u *		netaddr;
23
24	netaddr = &netofbuf[next_netofbuf];
25	next_netofbuf = (next_netofbuf + 1) % COUNTOF(netofbuf);
26
27	memcpy(netaddr, hostaddr, sizeof(*netaddr));
28
29	if (IS_IPV4(netaddr)) {
30		netnum = SRCADR(netaddr);
31
32		/*
33		 * We live in a modern CIDR world where the basement nets, which
34		 * used to be class A, are now probably associated with each
35		 * host address. So, for class-A nets, all bits are significant.
36		 */
37		if (IN_CLASSC(netnum))
38			netnum &= IN_CLASSC_NET;
39		else if (IN_CLASSB(netnum))
40			netnum &= IN_CLASSB_NET;
41
42		SET_ADDR4(netaddr, netnum);
43
44	} else if (IS_IPV6(netaddr))
45		/* assume the typical /64 subnet size */
46		zero_mem(&NSRCADR6(netaddr)[8], 8);
47#ifdef DEBUG
48	else {
49		msyslog(LOG_ERR, "netof unknown AF %d", AF(netaddr));
50		exit(1);
51	}
52#endif
53
54	return netaddr;
55}
56