external/bsd/ntp/dist/libntp/netof.c

   1 /*      $NetBSD$        */
   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 <stdio.h>
   8 #include <syslog.h>
   9
  10 #include "ntp_fp.h"
  11 #include "ntp_net.h"
  12 #include "ntp_stdlib.h"
  13 #include "ntp.h"
  14
  15 sockaddr_u *
  16 netof(
  17         sockaddr_u *hostaddr
  18         )
  19 {
  20         static sockaddr_u       netofbuf[8];
  21         static int              next_netofbuf;
  22         u_int32                 netnum;
  23         sockaddr_u *            netaddr;
  24
  25         netaddr = &netofbuf[next_netofbuf];
  26         next_netofbuf = (next_netofbuf + 1) % COUNTOF(netofbuf);
  27
  28         memcpy(netaddr, hostaddr, sizeof(*netaddr));
  29
  30         if (IS_IPV4(netaddr)) {
  31                 netnum = SRCADR(netaddr);
  32
  33                 /*
  34                  * We live in a modern CIDR world where the basement nets, which
  35                  * used to be class A, are now probably associated with each
  36                  * host address. So, for class-A nets, all bits are significant.
  37                  */
  38                 if (IN_CLASSC(netnum))
  39                         netnum &= IN_CLASSC_NET;
  40                 else if (IN_CLASSB(netnum))
  41                         netnum &= IN_CLASSB_NET;
  42
  43                 SET_ADDR4(netaddr, netnum);
  44
  45         } else if (IS_IPV6(netaddr))
  46                 /* assume the typical /64 subnet size */
  47                 memset(&NSRCADR6(netaddr)[8], 0, 8);
  48 #ifdef DEBUG
  49         else {
  50                 msyslog(LOG_ERR, "netof unknown AF %d", AF(netaddr));
  51                 exit(1);
  52         }
  53 #endif
  54
  55         return netaddr;
  56 }