dist/ntp/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
   9 #include "ntp_fp.h"
  10 #include "ntp_stdlib.h"
  11 #include "ntp.h"
  12
  13 #define NUM_NETOF_BUFS  10
  14 static struct sockaddr_storage ssbuf[NUM_NETOF_BUFS];
  15 static int next_ssbuf = 0;
  16
  17 struct sockaddr_storage*
  18 netof(
  19         struct sockaddr_storage* hostaddr
  20         )
  21 {
  22         register u_int32 netnum;
  23         struct sockaddr_storage *netaddr;
  24
  25         netaddr = &ssbuf[next_ssbuf++];
  26         if (next_ssbuf == NUM_NETOF_BUFS)
  27                 next_ssbuf = 0;
  28         memcpy(netaddr, hostaddr, sizeof(struct sockaddr_storage));
  29
  30         if(netaddr->ss_family == AF_INET) {
  31                 netnum = ((struct sockaddr_in*)netaddr)->sin_addr.s_addr;
  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                         ((struct sockaddr_in*)netaddr)->sin_addr.s_addr = netnum;
  43                  }
  44          else if(netaddr->ss_family == AF_INET6) {
  45                 /* Here we put 0 at the local link address so we get net address */
  46                   memset(&((struct sockaddr_in6*)netaddr)->sin6_addr.s6_addr[8], 0, 8*sizeof(u_char));
  47          }
  48
  49          return netaddr;
  50 }