pfil.c revision 109623 
190075Sobrien/*	$FreeBSD: head/sys/net/pfil.c 109623 2003-01-21 08:56:16Z alfred $	*/
290075Sobrien
390075Sobrien/*
490075Sobrien * Copyright (c) 1996 Matthew R. Green
5132718Skan * All rights reserved.
690075Sobrien *
7132718Skan * Redistribution and use in source and binary forms, with or without
890075Sobrien * modification, are permitted provided that the following conditions
990075Sobrien * are met:
1090075Sobrien * 1. Redistributions of source code must retain the above copyright
1190075Sobrien *    notice, this list of conditions and the following disclaimer.
12132718Skan * 2. Redistributions in binary form must reproduce the above copyright
1390075Sobrien *    notice, this list of conditions and the following disclaimer in the
1490075Sobrien *    documentation and/or other materials provided with the distribution.
1590075Sobrien * 3. The name of the author may not be used to endorse or promote products
1690075Sobrien *    derived from this software without specific prior written permission.
1790075Sobrien *
18132718Skan * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19169689Skan * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20169689Skan * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
2190075Sobrien * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22215841Sdim * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
23215841Sdim * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24215841Sdim * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
25215841Sdim * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26215841Sdim * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27215841Sdim * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28215841Sdim * SUCH DAMAGE.
2990075Sobrien */
3090075Sobrien
3190075Sobrien#include <sys/param.h>
3290075Sobrien#include <sys/errno.h>
3390075Sobrien#include <sys/malloc.h>
3490075Sobrien#include <sys/socket.h>
3590075Sobrien#include <sys/socketvar.h>
3690075Sobrien#include <sys/systm.h>
3790075Sobrien#include <sys/queue.h>
38146895Skan
39215841Sdim#include <net/if.h>
40#include <net/pfil.h>
41
42static void pfil_init(struct pfil_head *);
43static int pfil_list_add(pfil_list_t *,
44    int (*)(void *, int, struct ifnet *, int, struct mbuf **), int);
45static int pfil_list_remove(pfil_list_t *,
46    int (*)(void *, int, struct ifnet *, int, struct mbuf **));
47
48static void
49pfil_init(ph)
50	 struct pfil_head *ph;
51{
52
53	TAILQ_INIT(&ph->ph_in);
54	TAILQ_INIT(&ph->ph_out);
55	ph->ph_init = 1;
56}
57
58/*
59 * pfil_add_hook() adds a function to the packet filter hook.  the
60 * flags are:
61 *	PFIL_IN		call me on incoming packets
62 *	PFIL_OUT	call me on outgoing packets
63 *	PFIL_ALL	call me on all of the above
64 *	PFIL_WAITOK	OK to call malloc with 0.
65 */
66int
67pfil_add_hook(func, flags, ph)
68	int	(*func)(void *, int, struct ifnet *, int, struct mbuf **);
69	int	flags;
70	struct	pfil_head	*ph;
71{
72	int err = 0;
73
74	if (ph->ph_init == 0)
75		pfil_init(ph);
76
77	if (flags & PFIL_IN)
78		err = pfil_list_add(&ph->ph_in, func, flags & ~PFIL_OUT);
79	if (err)
80		return err;
81	if (flags & PFIL_OUT)
82		err = pfil_list_add(&ph->ph_out, func, flags & ~PFIL_IN);
83	if (err) {
84		if (flags & PFIL_IN)
85			pfil_list_remove(&ph->ph_in, func);
86		return err;
87	}
88	return 0;
89}
90
91static int
92pfil_list_add(list, func, flags)
93	pfil_list_t *list;
94	int	(*func)(void *, int, struct ifnet *, int, 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 ? 0 : M_NOWAIT);
101	if (pfh == NULL)
102		return ENOMEM;
103	pfh->pfil_func = func;
104	/*
105	 * insert the input list in reverse order of the output list
106	 * so that the same path is followed in or out of the kernel.
107	 */
108
109	if (flags & PFIL_IN)
110		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
111	else
112		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
113	return 0;
114}
115
116/*
117 * pfil_remove_hook removes a specific function from the packet filter
118 * hook list.
119 */
120int
121pfil_remove_hook(func, flags, ph)
122	int	(*func)(void *, int, struct ifnet *, int, struct mbuf **);
123	int	flags;
124	struct	pfil_head	*ph;
125{
126	int err = 0;
127
128	if (ph->ph_init == 0)
129		pfil_init(ph);
130
131	if (flags & PFIL_IN)
132		err = pfil_list_remove(&ph->ph_in, func);
133	if ((err == 0) && (flags & PFIL_OUT))
134		err = pfil_list_remove(&ph->ph_out, func);
135	return err;
136}
137
138/*
139 * pfil_list_remove is an internal function that takes a function off the
140 * specified list.
141 */
142static int
143pfil_list_remove(list, func)
144	pfil_list_t *list;
145	int	(*func)(void *, int, struct ifnet *, int, struct mbuf **);
146{
147	struct packet_filter_hook *pfh;
148
149	TAILQ_FOREACH(pfh, list, pfil_link)
150		if (pfh->pfil_func == func) {
151			TAILQ_REMOVE(list, pfh, pfil_link);
152			free(pfh, M_IFADDR);
153			return 0;
154		}
155	return ENOENT;
156}
157
158struct packet_filter_hook *
159pfil_hook_get(flag, ph)
160	int flag;
161	struct	pfil_head	*ph;
162{
163	if (ph->ph_init != 0)
164		switch (flag) {
165		case PFIL_IN:
166			return (TAILQ_FIRST(&ph->ph_in));
167		case PFIL_OUT:
168			return (TAILQ_FIRST(&ph->ph_out));
169		}
170	return NULL;
171}
172