if_disc.c revision 241610 
1/*-
2 * Copyright (c) 1982, 1986, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 *	From: @(#)if_loop.c	8.1 (Berkeley) 6/10/93
30 * $FreeBSD: head/sys/net/if_disc.c 241610 2012-10-16 13:37:54Z glebius $
31 */
32
33/*
34 * Discard interface driver for protocol testing and timing.
35 * (Based on the loopback.)
36 */
37
38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/kernel.h>
41#include <sys/malloc.h>
42#include <sys/module.h>
43#include <sys/mbuf.h>
44#include <sys/socket.h>
45#include <sys/sockio.h>
46
47#include <net/if.h>
48#include <net/if_clone.h>
49#include <net/if_types.h>
50#include <net/route.h>
51#include <net/bpf.h>
52
53#include "opt_inet.h"
54#include "opt_inet6.h"
55
56#ifdef TINY_DSMTU
57#define	DSMTU	(1024+512)
58#else
59#define DSMTU	65532
60#endif
61
62struct disc_softc {
63	struct ifnet *sc_ifp;
64};
65
66static int	discoutput(struct ifnet *, struct mbuf *,
67		    struct sockaddr *, struct route *);
68static void	discrtrequest(int, struct rtentry *, struct rt_addrinfo *);
69static int	discioctl(struct ifnet *, u_long, caddr_t);
70static int	disc_clone_create(struct if_clone *, int, caddr_t);
71static void	disc_clone_destroy(struct ifnet *);
72
73static const char discname[] = "disc";
74static MALLOC_DEFINE(M_DISC, discname, "Discard interface");
75
76static struct if_clone *disc_cloner;
77
78static int
79disc_clone_create(struct if_clone *ifc, int unit, caddr_t params)
80{
81	struct ifnet		*ifp;
82	struct disc_softc	*sc;
83
84	sc = malloc(sizeof(struct disc_softc), M_DISC, M_WAITOK | M_ZERO);
85	ifp = sc->sc_ifp = if_alloc(IFT_LOOP);
86	if (ifp == NULL) {
87		free(sc, M_DISC);
88		return (ENOSPC);
89	}
90
91	ifp->if_softc = sc;
92	if_initname(ifp, discname, unit);
93	ifp->if_mtu = DSMTU;
94	/*
95	 * IFF_LOOPBACK should not be removed from disc's flags because
96	 * it controls what PF-specific routes are magically added when
97	 * a network address is assigned to the interface.  Things just
98	 * won't work as intended w/o such routes because the output
99	 * interface selection for a packet is totally route-driven.
100	 * A valid alternative to IFF_LOOPBACK can be IFF_BROADCAST or
101	 * IFF_POINTOPOINT, but it would result in different properties
102	 * of the interface.
103	 */
104	ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
105	ifp->if_drv_flags = IFF_DRV_RUNNING;
106	ifp->if_ioctl = discioctl;
107	ifp->if_output = discoutput;
108	ifp->if_hdrlen = 0;
109	ifp->if_addrlen = 0;
110	ifp->if_snd.ifq_maxlen = 20;
111	if_attach(ifp);
112	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
113
114	return (0);
115}
116
117static void
118disc_clone_destroy(struct ifnet *ifp)
119{
120	struct disc_softc	*sc;
121
122	sc = ifp->if_softc;
123
124	bpfdetach(ifp);
125	if_detach(ifp);
126	if_free(ifp);
127
128	free(sc, M_DISC);
129}
130
131static int
132disc_modevent(module_t mod, int type, void *data)
133{
134
135	switch (type) {
136	case MOD_LOAD:
137		disc_cloner = if_clone_simple(discname, disc_clone_create,
138		    disc_clone_destroy, 0);
139		break;
140	case MOD_UNLOAD:
141		if_clone_detach(disc_cloner);
142		break;
143	default:
144		return (EOPNOTSUPP);
145	}
146	return (0);
147}
148
149static moduledata_t disc_mod = {
150	"if_disc",
151	disc_modevent,
152	NULL
153};
154
155DECLARE_MODULE(if_disc, disc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
156
157static int
158discoutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
159    struct route *ro)
160{
161	u_int32_t af;
162
163	M_ASSERTPKTHDR(m);
164
165	/* BPF writes need to be handled specially. */
166	if (dst->sa_family == AF_UNSPEC) {
167		bcopy(dst->sa_data, &af, sizeof(af));
168		dst->sa_family = af;
169	}
170
171	if (bpf_peers_present(ifp->if_bpf)) {
172		u_int af = dst->sa_family;
173		bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
174	}
175	m->m_pkthdr.rcvif = ifp;
176
177	ifp->if_opackets++;
178	ifp->if_obytes += m->m_pkthdr.len;
179
180	m_freem(m);
181	return (0);
182}
183
184/* ARGSUSED */
185static void
186discrtrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
187{
188	RT_LOCK_ASSERT(rt);
189	rt->rt_rmx.rmx_mtu = DSMTU;
190}
191
192/*
193 * Process an ioctl request.
194 */
195static int
196discioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
197{
198	struct ifaddr *ifa;
199	struct ifreq *ifr = (struct ifreq *)data;
200	int error = 0;
201
202	switch (cmd) {
203
204	case SIOCSIFADDR:
205		ifp->if_flags |= IFF_UP;
206		ifa = (struct ifaddr *)data;
207		if (ifa != 0)
208			ifa->ifa_rtrequest = discrtrequest;
209		/*
210		 * Everything else is done at a higher level.
211		 */
212		break;
213
214	case SIOCADDMULTI:
215	case SIOCDELMULTI:
216		if (ifr == 0) {
217			error = EAFNOSUPPORT;		/* XXX */
218			break;
219		}
220		switch (ifr->ifr_addr.sa_family) {
221
222#ifdef INET
223		case AF_INET:
224			break;
225#endif
226#ifdef INET6
227		case AF_INET6:
228			break;
229#endif
230
231		default:
232			error = EAFNOSUPPORT;
233			break;
234		}
235		break;
236
237	case SIOCSIFMTU:
238		ifp->if_mtu = ifr->ifr_mtu;
239		break;
240
241	default:
242		error = EINVAL;
243	}
244	return (error);
245}
246