pfil.c revision 1.8 
1/*	$NetBSD: pfil.c,v 1.8 1999/06/18 05:59:20 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. 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
43typedef TAILQ_HEAD(, packet_filter_hook) pfil_list_t;
44pfil_list_t pfil_in_list;
45pfil_list_t pfil_out_list;
46static int done_pfil_init;
47
48static void pfil_init __P((void));
49static void pfil_list_add(pfil_list_t *,
50    int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
51static void pfil_list_remove(pfil_list_t,
52    int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)));
53
54static void
55pfil_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 */
71void
72pfil_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
87static void
88pfil_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 */
116void
117pfil_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 */
136static void
137pfil_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
156struct packet_filter_hook *
157pfil_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