pfilt.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static	char	*sccsid = "@(#)pfilt.c	4.2	(ULTRIX)	2/26/91";
#endif lint
/************************************************************************
 *									*
 *			Copyright (c) 1989 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.	*
 *									*
 ************************************************************************/

/*
 * Modification History:
 *
 *  2-Aug-89	Jeffrey Mogul/DECWRL
 *	Slight restructuring.
 *
 * 13-Jun-89	jsd
 *	Created this module for use with the Ethernet Packet Filter
 *
 */

#include <sys/socket.h>
#include <sys/time.h>	/* for timeval struct in pfilt.h */
#include <sys/file.h>
#include <sys/errno.h>
#include <net/if.h>
#include <net/pfilt.h>
#include <stdio.h>

#define	PFPREFIX	"/dev/pf/pfilt"		/* prefix for device names */

/* define this for reverse compatibility */
#define	PFCOMPATNAME	"/dev/eneta0"		/* old style name */

#define	PFMAXMINORS	256			/* 8-bit minor device field */

extern int errno;

/*
 * pfopen(ifname, flags): to support access to the Ethernet Packet Filter.
 * (using kernel option PACKETFILTER, pseudo-device packetfilter)
 *
 * ifname is a ptr to the Ethernet device name ("ln0", "qe0", "pf0", etc.)
 *	or NULL for default
 * flags are passed to the open() system call.
 *
 * return value:
 *	special device file descriptor on success
 *	-1 on failure with errno set to indicate the error
 *
 */
pfopen(ifname, flags)
char *ifname;			/* "qe0", "ln0", "ni1", "pf0", etc. or NULL */
int flags;
{
	int i;			/* loop counter */
	int fd;			/* file descriptor */
	char tryname[128];	/* device name: "/dev/pf/pfiltnn" */
	char genif[16];		/* generic interface name, if needed */
	static int setif();

	if (ifname && (ifname[0] == 0))
	    ifname = NULL;	/* change empty string to NULL string */

#ifdef	PFCOMPATNAME
	/* backwards compatible with Stanford-style packet filter */
	if ((fd = open(PFCOMPATNAME, flags, 0)) >= 0) {
	    return(setif(fd, ifname));
	}
#endif	PFCOMPATNAME

	/* find next available device under the /dev/pf directory */
	for (i = 0; i < PFMAXMINORS; i++) {
		sprintf(tryname, "%s%d", PFPREFIX, i);
		fd = open(tryname, flags, 0);
		if (fd < 0) {
			switch (errno) {
			case EBUSY:	/* device in use */
				continue;	/* try the next entry */
			case ENOENT:	/* ran out of filenames */
			case ENXIO:	/* no more configured in kernel */
			default:	/* something else went wrong */
				return(-1);
			}
		}
		/* open succeeded, set the interface name */
		return(setif(fd, ifname));
	}
	return(-1);	/* didn't find an openable device */
}

static int setif(fd, ifname)
int fd;
char *ifname;
{
	if (ifname == NULL)	/* use default */
	    return(fd);

	if (ioctl(fd, EIOCSETIF, ifname) < 0) {
		close(fd);
		return(-1);
	}
	/* return the file descriptor */
	return(fd);
}