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pfil.c revision 1.11 
      1 /*	$NetBSD: pfil.c,v 1.11 2000/02/20 00:56:33 darrenr 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 void pfil_list_add(pfil_list_t *,
     45     int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
     46 static void 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 void
     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 
     75 	if (ph->ph_init == 0)
     76 		pfil_init(ph);
     77 
     78 	if (flags & PFIL_IN)
     79 		pfil_list_add(&ph->ph_in, func, flags);
     80 	if (flags & PFIL_OUT)
     81 		pfil_list_add(&ph->ph_out, func, flags);
     82 }
     83 
     84 static void
     85 pfil_list_add(list, func, flags)
     86 	pfil_list_t *list;
     87 	int	(*func) __P((void *, int, struct ifnet *, int,
     88 			     struct mbuf **));
     89 	int flags;
     90 {
     91 	struct packet_filter_hook *pfh;
     92 
     93 	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
     94 	    flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
     95 	if (pfh == NULL)
     96 		panic("no memory for packet filter hook");
     97 	pfh->pfil_func = func;
     98 	/*
     99 	 * insert the input list in reverse order of the output list
    100 	 * so that the same path is followed in or out of the kernel.
    101 	 */
    102 	TAILQ_INSERT_TAIL(list, pfh, pfil_link);
    103 }
    104 
    105 /*
    106  * pfil_remove_hook removes a specific function from the packet filter
    107  * hook list.
    108  */
    109 void
    110 pfil_remove_hook(func, flags, ph)
    111 	int	(*func) __P((void *, int, struct ifnet *, int,
    112 			     struct mbuf **));
    113 	int	flags;
    114 	struct	pfil_head	*ph;
    115 {
    116 
    117 	if (ph->ph_init == 0)
    118 		pfil_init(ph);
    119 
    120 	if (flags & PFIL_IN)
    121 		pfil_list_remove(&ph->ph_in, func);
    122 	if (flags & PFIL_OUT)
    123 		pfil_list_remove(&ph->ph_out, func);
    124 }
    125 
    126 /*
    127  * pfil_list_remove is an internal function that takes a function off the
    128  * specified list.
    129  */
    130 static void
    131 pfil_list_remove(list, func)
    132 	pfil_list_t *list;
    133 	int	(*func) __P((void *, int, struct ifnet *, int,
    134 			     struct mbuf **));
    135 {
    136 	struct packet_filter_hook *pfh;
    137 
    138 	for (pfh = list->tqh_first; pfh; pfh = pfh->pfil_link.tqe_next)
    139 		if (pfh->pfil_func == func) {
    140 			TAILQ_REMOVE(list, pfh, pfil_link);
    141 			free(pfh, M_IFADDR);
    142 			return;
    143 		}
    144 	printf("pfil_list_remove:  no function on list\n");
    145 #ifdef DIAGNOSTIC
    146 	panic("pfil_list_remove");
    147 #endif
    148 }
    149 
    150 struct packet_filter_hook *
    151 pfil_hook_get(flag, ph)
    152 	int flag;
    153 	struct	pfil_head	*ph;
    154 {
    155 	if (ph->ph_init != 0)
    156 		switch (flag) {
    157 		case PFIL_IN:
    158 			return (ph->ph_in.tqh_first);
    159 		case PFIL_OUT:
    160 			return (ph->ph_out.tqh_first);
    161 		}
    162 	return NULL;
    163 }
    164