1 /* 2 * Copyright (c) 1983 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #if defined(LIBC_SCCS) && !defined(lint) 8 static char sccsid[] = "@(#)inet_netof.c 5.3 (Berkeley) 10/01/87"; 9 #endif LIBC_SCCS and not lint 10 11 #include <sys/types.h> 12 #include <netinet/in.h> 13 14 /* 15 * Return the network number from an internet 16 * address; handles class a/b/c network #'s. 17 */ 18 u_long 19 inet_netof(in) 20 struct in_addr in; 21 { 22 register u_long i = ntohl(in.s_addr); 23 24 if (IN_CLASSA(i)) 25 return (((i)&IN_CLASSA_NET) >> IN_CLASSA_NSHIFT); 26 else if (IN_CLASSB(i)) 27 return (((i)&IN_CLASSB_NET) >> IN_CLASSB_NSHIFT); 28 else 29 return (((i)&IN_CLASSC_NET) >> IN_CLASSC_NSHIFT); 30 } 31