/contrib/ntp/libntp/netof.c
C | 48 lines | 31 code | 7 blank | 10 comment | 10 complexity | ff7aab6a269406e0197662693ff4c2f2 MD5 | raw file
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 <stdio.h> 6 7#include "ntp_fp.h" 8#include "ntp_stdlib.h" 9#include "ntp.h" 10 11#define NUM_NETOF_BUFS 10 12static struct sockaddr_storage ssbuf[NUM_NETOF_BUFS]; 13static int next_ssbuf = 0; 14 15struct sockaddr_storage* 16netof( 17 struct sockaddr_storage* hostaddr 18 ) 19{ 20 register u_int32 netnum; 21 struct sockaddr_storage *netaddr; 22 23 netaddr = &ssbuf[next_ssbuf++]; 24 if (next_ssbuf == NUM_NETOF_BUFS) 25 next_ssbuf = 0; 26 memcpy(netaddr, hostaddr, sizeof(struct sockaddr_storage)); 27 28 if(netaddr->ss_family == AF_INET) { 29 netnum = ((struct sockaddr_in*)netaddr)->sin_addr.s_addr; 30 31 /* 32 * We live in a modern CIDR world where the basement nets, which 33 * used to be class A, are now probably associated with each 34 * host address. So, for class-A nets, all bits are significant. 35 */ 36 if(IN_CLASSC(netnum)) 37 netnum &= IN_CLASSC_NET; 38 else if (IN_CLASSB(netnum)) 39 netnum &= IN_CLASSB_NET; 40 ((struct sockaddr_in*)netaddr)->sin_addr.s_addr = netnum; 41 } 42 else if(netaddr->ss_family == AF_INET6) { 43 /* Here we put 0 at the local link address so we get net address */ 44 memset(&((struct sockaddr_in6*)netaddr)->sin6_addr.s6_addr[8], 0, 8*sizeof(u_char)); 45 } 46 47 return netaddr; 48}