add getifaddrs(3), from bsdi4.

this will help future apps from complexity of SIOCGIFCONF.
NOTE: getifaddrs(3) uses sysctl interface, not SIOCGIFCONF.

src/include/Makefile

@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.77 2000/02/19 15:28:41 deraadt Exp $
+#	$OpenBSD: Makefile,v 1.78 2000/02/23 06:55:59 itojun Exp $
 #	$NetBSD: Makefile,v 1.59 1996/05/15 21:36:43 jtc Exp $
 
 #	@(#)Makefile	5.45.1.1 (Berkeley) 5/6/91
@@ -10,9 +10,9 @@
 
 FILES=	a.out.h ar.h assert.h bitstring.h blf.h bm.h cast.h cpio.h ctype.h \
 	curses.h db.h dbm.h des.h dirent.h disktab.h elf_abi.h err.h fnmatch.h \
-	fstab.h fts.h glob.h grp.h ieeefp.h inttypes.h iso646.h kvm.h \
-	langinfo.h libgen.h limits.h locale.h malloc.h math.h md4.h md5.h \
-	memory.h mpool.h ndbm.h netdb.h netgroup.h nlist.h nl_types.h \
+	fstab.h fts.h glob.h grp.h ieeefp.h ifaddrs.h inttypes.h iso646.h \
+	kvm.h langinfo.h libgen.h limits.h locale.h malloc.h math.h md4.h \
+	md5.h memory.h mpool.h ndbm.h netdb.h netgroup.h nlist.h nl_types.h \
 	olf_abi.h paths.h poll.h pwd.h ranlib.h re_comp.h regex.h resolv.h \
 	rmd160.h search.h setjmp.h sgtty.h sha1.h skipjack.h signal.h stab.h \
 	stdbool.h stddef.h stdio.h stdlib.h string.h strings.h struct.h sysexits.h \

src/include/ifaddrs.h

@@ -0,0 +1,55 @@
+/*	$OpenBSD: ifaddrs.h,v 1.1 2000/02/23 06:55:59 itojun Exp $	*/
+
+/*
+ * Copyright (c) 1995, 1999
+ *	Berkeley Software Design, Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	BSDI ifaddrs.h,v 2.4 1999/03/15 20:59:28 jch Exp
+ */
+
+#ifndef	_IFADDRS_H_
+#define	_IFADDRS_H_
+
+struct ifaddrs {
+	struct ifaddrs  *ifa_next;
+	char		*ifa_name;
+	u_int		 ifa_flags;
+	struct sockaddr	*ifa_addr;
+	struct sockaddr	*ifa_netmask;
+	struct sockaddr	*ifa_dstaddr;
+	void		*ifa_data;
+};
+
+/*
+ * This may have been defined in <net/if.h>.  Note that if <net/if.h> is
+ * to be included it must be included before this header file.
+ */
+#ifndef	ifa_broadaddr
+#define	ifa_broadaddr	ifa_dstaddr	/* broadcast address interface */
+#endif
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+extern int getifaddrs __P((struct ifaddrs **));
+__END_DECLS
+
+#endif