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pfil.c revision 1.5 
      1 /*	$NetBSD: pfil.c,v 1.5 1996/12/20 08:40:46 mrg 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *      This product includes software developed by Matthew R. Green for
     18  *      the NetBSD Project.
     19  * 4. The name of the author may not be used to endorse or promote products
     20  *    derived from this software without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/param.h>
     36 #include <sys/errno.h>
     37 #include <sys/malloc.h>
     38 #include <sys/socket.h>
     39 #include <sys/socketvar.h>
     40 #include <sys/systm.h>
     41 #include <sys/proc.h>
     42 #include <sys/queue.h>
     43 
     44 #include <net/if.h>
     45 #include <net/pfil.h>
     46 
     47 typedef LIST_HEAD(, packet_filter_hook) pfil_list_t;
     48 pfil_list_t pfil_in_list;
     49 pfil_list_t pfil_out_list;
     50 static int done_pfil_init;
     51 
     52 void pfil_init __P((void));
     53 void pfil_list_add(pfil_list_t *,
     54     int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
     55 void pfil_list_remove(struct packet_filter_hook *,
     56     int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)));
     57 
     58 void
     59 pfil_init()
     60 {
     61 	LIST_INIT(&pfil_in_list);
     62 	LIST_INIT(&pfil_out_list);
     63 	done_pfil_init = 1;
     64 }
     65 
     66 /*
     67  * pfil_add_hook() adds a function to the packet filter hook.  the
     68  * flags are:
     69  *	PFIL_IN		call me on incoming packets
     70  *	PFIL_OUT	call me on outgoing packets
     71  *	PFIL_ALL	call me on all of the above
     72  *	PFIL_WAITOK	OK to call malloc with M_WAITOK.
     73  */
     74 void
     75 pfil_add_hook(func, flags)
     76 	int	(*func) __P((void *, int, struct ifnet *, int,
     77 			     struct mbuf **));
     78 	int	flags;
     79 {
     80 
     81 	if (done_pfil_init == 0)
     82 		pfil_init();
     83 
     84 	if (flags & PFIL_IN)
     85 		pfil_list_add(&pfil_in_list, func, flags);
     86 	if (flags & PFIL_OUT)
     87 		pfil_list_add(&pfil_out_list, func, flags);
     88 }
     89 
     90 void
     91 pfil_list_add(list, func, flags)
     92 	pfil_list_t *list;
     93 	int	(*func) __P((void *, int, struct ifnet *, int,
     94 			     struct mbuf **));
     95 	int	flags;
     96 {
     97 	struct packet_filter_hook *pfh;
     98 
     99 	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
    100 	    flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
    101 	if (pfh == NULL)
    102 		panic("no memory for packet filter hook");
    103 
    104 	pfh->pfil_func = func;
    105 	LIST_INSERT_HEAD(list, pfh, pfil_link);
    106 }
    107 
    108 /*
    109  * pfil_remove_hook removes a specific function from the packet filter
    110  * hook list.
    111  */
    112 void
    113 pfil_remove_hook(func, flags)
    114 	int	(*func) __P((void *, int, struct ifnet *, int,
    115 			     struct mbuf **));
    116 	int	flags;
    117 {
    118 
    119 	if (done_pfil_init == 0)
    120 		pfil_init();
    121 
    122 	if (flags & PFIL_IN)
    123 		pfil_list_remove(pfil_in_list.lh_first, func);
    124 	if (flags & PFIL_OUT)
    125 		pfil_list_remove(pfil_out_list.lh_first, func);
    126 }
    127 
    128 /*
    129  * pfil_list_remove is an internal function that takes a function off the
    130  * specified list.
    131  */
    132 void
    133 pfil_list_remove(list, func)
    134 	struct packet_filter_hook *list;
    135 	int	(*func) __P((void *, int, struct ifnet *, int,
    136 			     struct mbuf **));
    137 {
    138 	struct packet_filter_hook *pfh;
    139 
    140 	for (pfh = list; pfh; pfh = pfh->pfil_link.le_next)
    141 		if (pfh->pfil_func == func) {
    142 			LIST_REMOVE(pfh, pfil_link);
    143 			free(pfh, M_IFADDR);
    144 			return;
    145 		}
    146 	printf("pfil_list_remove:  no function on list\n");
    147 #ifdef DIAGNOSTIC
    148 	panic("pfil_list_remove");
    149 #endif
    150 }
    151 
    152 struct packet_filter_hook *
    153 pfil_hook_get(flag)
    154 	int flag;
    155 {
    156 	if (done_pfil_init)
    157 		switch (flag) {
    158 		case PFIL_IN:
    159 			return (pfil_in_list.lh_first);
    160 		case PFIL_OUT:
    161 			return (pfil_out_list.lh_first);
    162 		}
    163 	return NULL;
    164 }
    165