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pfil.c revision 1.15 
      1 /*	$NetBSD: pfil.c,v 1.15 2000/02/23 02:35:42 mycroft Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1996 Matthew R. Green
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. The name of the author may not be used to endorse or promote products
     16  *    derived from this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     23  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     25  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     26  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     28  * SUCH DAMAGE.
     29  */
     30 
     31 #include <sys/param.h>
     32 #include <sys/errno.h>
     33 #include <sys/malloc.h>
     34 #include <sys/socket.h>
     35 #include <sys/socketvar.h>
     36 #include <sys/systm.h>
     37 #include <sys/proc.h>
     38 #include <sys/queue.h>
     39 
     40 #include <net/if.h>
     41 #include <net/pfil.h>
     42 
     43 static void pfil_init __P((struct pfil_head *));
     44 static int pfil_list_add(pfil_list_t *,
     45     int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
     46 static int pfil_list_remove(pfil_list_t *,
     47     int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)));
     48 
     49 static void
     50 pfil_init(ph)
     51 	 struct pfil_head *ph;
     52 {
     53 
     54 	TAILQ_INIT(&ph->ph_in);
     55 	TAILQ_INIT(&ph->ph_out);
     56 	ph->ph_init = 1;
     57 }
     58 
     59 /*
     60  * pfil_add_hook() adds a function to the packet filter hook.  the
     61  * flags are:
     62  *	PFIL_IN		call me on incoming packets
     63  *	PFIL_OUT	call me on outgoing packets
     64  *	PFIL_ALL	call me on all of the above
     65  *	PFIL_WAITOK	OK to call malloc with M_WAITOK.
     66  */
     67 int
     68 pfil_add_hook(func, flags, ph)
     69 	int	(*func) __P((void *, int, struct ifnet *, int,
     70 			     struct mbuf **));
     71 	int	flags;
     72 	struct	pfil_head	*ph;
     73 {
     74 	int err = 0;
     75 
     76 	if (ph->ph_init == 0)
     77 		pfil_init(ph);
     78 
     79 	if (flags & PFIL_IN)
     80 		err = pfil_list_add(&ph->ph_in, func, flags & ~PFIL_OUT);
     81 	if (err)
     82 		return err;
     83 	if (flags & PFIL_OUT)
     84 		err = pfil_list_add(&ph->ph_out, func, flags & ~PFIL_IN);
     85 	if (err) {
     86 		if (flags & PFIL_IN)
     87 			pfil_list_remove(&ph->ph_in, func);
     88 		return err;
     89 	}
     90 	return 0;
     91 }
     92 
     93 static int
     94 pfil_list_add(list, func, flags)
     95 	pfil_list_t *list;
     96 	int	(*func) __P((void *, int, struct ifnet *, int,
     97 			     struct mbuf **));
     98 	int flags;
     99 {
    100 	struct packet_filter_hook *pfh;
    101 
    102 	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
    103 	    flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
    104 	if (pfh == NULL)
    105 		return ENOMEM;
    106 	pfh->pfil_func = func;
    107 	/*
    108 	 * insert the input list in reverse order of the output list
    109 	 * so that the same path is followed in or out of the kernel.
    110 	 */
    111 
    112 	if (flags & PFIL_IN)
    113 		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
    114 	else
    115 		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
    116 	return 0;
    117 }
    118 
    119 /*
    120  * pfil_remove_hook removes a specific function from the packet filter
    121  * hook list.
    122  */
    123 int
    124 pfil_remove_hook(func, flags, ph)
    125 	int	(*func) __P((void *, int, struct ifnet *, int,
    126 			     struct mbuf **));
    127 	int	flags;
    128 	struct	pfil_head	*ph;
    129 {
    130 	int err = 0;
    131 
    132 	if (ph->ph_init == 0)
    133 		pfil_init(ph);
    134 
    135 	if (flags & PFIL_IN)
    136 		err = pfil_list_remove(&ph->ph_in, func);
    137 	if ((err == 0) && (flags & PFIL_OUT))
    138 		err = pfil_list_remove(&ph->ph_out, func);
    139 	return err;
    140 }
    141 
    142 /*
    143  * pfil_list_remove is an internal function that takes a function off the
    144  * specified list.
    145  */
    146 static int
    147 pfil_list_remove(list, func)
    148 	pfil_list_t *list;
    149 	int	(*func) __P((void *, int, struct ifnet *, int,
    150 			     struct mbuf **));
    151 {
    152 	struct packet_filter_hook *pfh;
    153 
    154 	for (pfh = list->tqh_first; pfh; pfh = pfh->pfil_link.tqe_next)
    155 		if (pfh->pfil_func == func) {
    156 			TAILQ_REMOVE(list, pfh, pfil_link);
    157 			free(pfh, M_IFADDR);
    158 			return 0;
    159 		}
    160 	return ENOENT;
    161 }
    162 
    163 struct packet_filter_hook *
    164 pfil_hook_get(flag, ph)
    165 	int flag;
    166 	struct	pfil_head	*ph;
    167 {
    168 	if (ph->ph_init != 0)
    169 		switch (flag) {
    170 		case PFIL_IN:
    171 			return (ph->ph_in.tqh_first);
    172 		case PFIL_OUT:
    173 			return (ph->ph_out.tqh_first);
    174 		}
    175 	return NULL;
    176 }
    177