inet.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 219 行

#ifndef lint
static	char	*sccsid = "@(#)inet.c	4.1	(ULTRIX)	7/2/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1984,1988 by			*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/
/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */
/*
#ifndef lint
static char sccsid[] = "inet.c	5.5 (Berkeley) 5/28/87";
#endif not lint
*/
/*
 * Temporarily, copy these routines from the kernel,
 * as we need to know about subnets.
 */
#include "defs.h"

extern struct interface *ifnet;

/*
 * Formulate an Internet address from network + host.
 */
struct in_addr
inet_makeaddr(net, host)
	u_long net, host;
{
	register struct interface *ifp;
	register u_long mask;
	u_long addr;

	if (IN_CLASSA(net))
		mask = IN_CLASSA_HOST;
	else if (IN_CLASSB(net))
		mask = IN_CLASSB_HOST;
	else
		mask = IN_CLASSC_HOST;
	for (ifp = ifnet; ifp; ifp = ifp->int_next)
		if ((ifp->int_netmask & net) == ifp->int_net) {
			mask = ~ifp->int_subnetmask;
			break;
		}
	addr = net | (host & mask);
	addr = htonl(addr);
	return (*(struct in_addr *)&addr);
}

/*
 * Return the network number from an internet address.
 */
inet_netof(in)
	struct in_addr in;
{
	register u_long i = ntohl(in.s_addr);
	register u_long net;
	register struct interface *ifp;

	if (IN_CLASSA(i))
		net = i & IN_CLASSA_NET;
	else if (IN_CLASSB(i))
		net = i & IN_CLASSB_NET;
	else
		net = i & IN_CLASSC_NET;

	/*
	 * Check whether network is a subnet;
	 * if so, return subnet number.
	 */
	for (ifp = ifnet; ifp; ifp = ifp->int_next)
		if ((ifp->int_netmask & net) == ifp->int_net)
			return (i & ifp->int_subnetmask);
	return (net);
}

/*
 * Return the host portion of an internet address.
 */
inet_lnaof(in)
	struct in_addr in;
{
	register u_long i = ntohl(in.s_addr);
	register u_long net, host;
	register struct interface *ifp;

	if (IN_CLASSA(i)) {
		net = i & IN_CLASSA_NET;
		host = i & IN_CLASSA_HOST;
	} else if (IN_CLASSB(i)) {
		net = i & IN_CLASSB_NET;
		host = i & IN_CLASSB_HOST;
	} else {
		net = i & IN_CLASSC_NET;
		host = i & IN_CLASSC_HOST;
	}

	/*
	 * Check whether network is a subnet;
	 * if so, use the modified interpretation of `host'.
	 */
	for (ifp = ifnet; ifp; ifp = ifp->int_next)
		if ((ifp->int_netmask & net) == ifp->int_net)
			return (host &~ ifp->int_subnetmask);
	return (host);
}

/*
 * Return RTF_HOST if the address is
 * for an Internet host, RTF_SUBNET for a subnet,
 * 0 for a network.
 */
inet_rtflags(sin)
	struct sockaddr_in *sin;
{
	register u_long i = ntohl(sin->sin_addr.s_addr);
	register u_long net, host;
	register struct interface *ifp;

	if (IN_CLASSA(i)) {
		net = i & IN_CLASSA_NET;
		host = i & IN_CLASSA_HOST;
	} else if (IN_CLASSB(i)) {
		net = i & IN_CLASSB_NET;
		host = i & IN_CLASSB_HOST;
	} else {
		net = i & IN_CLASSC_NET;
		host = i & IN_CLASSC_HOST;
	}

	/*
	 * Check whether this network is subnetted;
	 * if so, check whether this is a subnet or a host.
	 */
	for (ifp = ifnet; ifp; ifp = ifp->int_next)
		if (net == ifp->int_net) {
			if (host &~ ifp->int_subnetmask)
				return (RTF_HOST);
			else if (ifp->int_subnetmask != ifp->int_netmask)
				return (RTF_SUBNET);
			else
				return (0);		/* network */
		}
	if (host == 0)
		return (0);	/* network */
	else
		return (RTF_HOST);
}

/*
 * Return true if a route to subnet/host of route rt should be sent to dst.
 * Send it only if dst is on the same logical network if not "internal",
 * otherwise only if the route is the "internal" route for the logical net.
 */
inet_sendroute(rt, dst)
	struct rt_entry *rt;
	struct sockaddr_in *dst;
{
	register u_long r =
	    ntohl(((struct sockaddr_in *)&rt->rt_dst)->sin_addr.s_addr);
	register u_long d = ntohl(dst->sin_addr.s_addr);

	if (IN_CLASSA(r)) {
		if ((r & IN_CLASSA_NET) == (d & IN_CLASSA_NET)) {
			if ((r & IN_CLASSA_HOST) == 0)
				return ((rt->rt_state & RTS_INTERNAL) == 0);
			return (1);
		}
		if (r & IN_CLASSA_HOST)
			return (0);
		return ((rt->rt_state & RTS_INTERNAL) != 0);
	} else if (IN_CLASSB(r)) {
		if ((r & IN_CLASSB_NET) == (d & IN_CLASSB_NET)) {
			if ((r & IN_CLASSB_HOST) == 0)
				return ((rt->rt_state & RTS_INTERNAL) == 0);
			return (1);
		}
		if (r & IN_CLASSB_HOST)
			return (0);
		return ((rt->rt_state & RTS_INTERNAL) != 0);
	} else {
		if ((r & IN_CLASSC_NET) == (d & IN_CLASSC_NET)) {
			if ((r & IN_CLASSC_HOST) == 0)
				return ((rt->rt_state & RTS_INTERNAL) == 0);
			return (1);
		}
		if (r & IN_CLASSC_HOST)
			return (0);
		return ((rt->rt_state & RTS_INTERNAL) != 0);
	}
}