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pfil.c revision 1.7.12.1 
      1 /*	$NetBSD: pfil.c,v 1.7.12.1 1999/11/30 13:35:13 itojun 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 typedef TAILQ_HEAD(, packet_filter_hook) pfil_list_t;
     44 pfil_list_t pfil_in_list;
     45 pfil_list_t pfil_out_list;
     46 static int done_pfil_init;
     47 
     48 static void pfil_init __P((void));
     49 static void pfil_list_add(pfil_list_t *,
     50     int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
     51 static void pfil_list_remove(pfil_list_t,
     52     int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)));
     53 
     54 static void
     55 pfil_init()
     56 {
     57 
     58 	TAILQ_INIT(&pfil_in_list);
     59 	TAILQ_INIT(&pfil_out_list);
     60 	done_pfil_init = 1;
     61 }
     62 
     63 /*
     64  * pfil_add_hook() adds a function to the packet filter hook.  the
     65  * flags are:
     66  *	PFIL_IN		call me on incoming packets
     67  *	PFIL_OUT	call me on outgoing packets
     68  *	PFIL_ALL	call me on all of the above
     69  *	PFIL_WAITOK	OK to call malloc with M_WAITOK.
     70  */
     71 void
     72 pfil_add_hook(func, flags)
     73 	int	(*func) __P((void *, int, struct ifnet *, int,
     74 			     struct mbuf **));
     75 	int	flags;
     76 {
     77 
     78 	if (done_pfil_init == 0)
     79 		pfil_init();
     80 
     81 	if (flags & PFIL_IN)
     82 		pfil_list_add(&pfil_in_list, func, PFIL_IN);
     83 	if (flags & PFIL_OUT)
     84 		pfil_list_add(&pfil_out_list, func, PFIL_OUT);
     85 }
     86 
     87 static void
     88 pfil_list_add(list, func, flags)
     89 	pfil_list_t *list;
     90 	int	(*func) __P((void *, int, struct ifnet *, int,
     91 			     struct mbuf **));
     92 	int	flags;
     93 {
     94 	struct packet_filter_hook *pfh;
     95 
     96 	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
     97 	    flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
     98 	if (pfh == NULL)
     99 		panic("no memory for packet filter hook");
    100 
    101 	pfh->pfil_func = func;
    102 	/*
    103 	 * insert the input list in reverse order of the output list
    104 	 * so that the same path is followed in or out of the kernel.
    105 	 */
    106 	if (flags & PFIL_IN)
    107 		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
    108 	else
    109 		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
    110 }
    111 
    112 /*
    113  * pfil_remove_hook removes a specific function from the packet filter
    114  * hook list.
    115  */
    116 void
    117 pfil_remove_hook(func, flags)
    118 	int	(*func) __P((void *, int, struct ifnet *, int,
    119 			     struct mbuf **));
    120 	int	flags;
    121 {
    122 
    123 	if (done_pfil_init == 0)
    124 		pfil_init();
    125 
    126 	if (flags & PFIL_IN)
    127 		pfil_list_remove(pfil_in_list, func);
    128 	if (flags & PFIL_OUT)
    129 		pfil_list_remove(pfil_out_list, func);
    130 }
    131 
    132 /*
    133  * pfil_list_remove is an internal function that takes a function off the
    134  * specified list.
    135  */
    136 static void
    137 pfil_list_remove(list, func)
    138 	pfil_list_t list;
    139 	int	(*func) __P((void *, int, struct ifnet *, int,
    140 			     struct mbuf **));
    141 {
    142 	struct packet_filter_hook *pfh;
    143 
    144 	for (pfh = list.tqh_first; pfh; pfh = pfh->pfil_link.tqe_next)
    145 		if (pfh->pfil_func == func) {
    146 			TAILQ_REMOVE(&list, pfh, pfil_link);
    147 			free(pfh, M_IFADDR);
    148 			return;
    149 		}
    150 	printf("pfil_list_remove:  no function on list\n");
    151 #ifdef DIAGNOSTIC
    152 	panic("pfil_list_remove");
    153 #endif
    154 }
    155 
    156 struct packet_filter_hook *
    157 pfil_hook_get(flag)
    158 	int flag;
    159 {
    160 
    161 	if (done_pfil_init)
    162 		switch (flag) {
    163 		case PFIL_IN:
    164 			return (pfil_in_list.tqh_first);
    165 		case PFIL_OUT:
    166 			return (pfil_out_list.tqh_first);
    167 		}
    168 	return NULL;
    169 }
    170