1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1993
5 *	The Regents of the University of California.  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. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 *	From: @(#)if_loop.c	8.1 (Berkeley) 6/10/93
32 * $FreeBSD$
33 */
34
35/*
36 * Discard interface driver for protocol testing and timing.
37 * (Based on the loopback.)
38 */
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/kernel.h>
43#include <sys/malloc.h>
44#include <sys/module.h>
45#include <sys/mbuf.h>
46#include <sys/socket.h>
47#include <sys/sockio.h>
48
49#include <net/if.h>
50#include <net/if_var.h>
51#include <net/if_clone.h>
52#include <net/if_types.h>
53#include <net/route.h>
54#include <net/bpf.h>
55#include <net/vnet.h>
56
57#include "opt_inet.h"
58#include "opt_inet6.h"
59
60#ifdef TINY_DSMTU
61#define	DSMTU	(1024+512)
62#else
63#define DSMTU	65532
64#endif
65
66struct disc_softc {
67	struct ifnet *sc_ifp;
68};
69
70static int	discoutput(struct ifnet *, struct mbuf *,
71		    const struct sockaddr *, struct route *);
72static int	discioctl(struct ifnet *, u_long, caddr_t);
73static int	disc_clone_create(struct if_clone *, int, caddr_t);
74static void	disc_clone_destroy(struct ifnet *);
75
76static const char discname[] = "disc";
77static MALLOC_DEFINE(M_DISC, discname, "Discard interface");
78
79VNET_DEFINE_STATIC(struct if_clone *, disc_cloner);
80#define	V_disc_cloner	VNET(disc_cloner)
81
82static int
83disc_clone_create(struct if_clone *ifc, int unit, caddr_t params)
84{
85	struct ifnet		*ifp;
86	struct disc_softc	*sc;
87
88	sc = malloc(sizeof(struct disc_softc), M_DISC, M_WAITOK | M_ZERO);
89	ifp = sc->sc_ifp = if_alloc(IFT_LOOP);
90	if (ifp == NULL) {
91		free(sc, M_DISC);
92		return (ENOSPC);
93	}
94
95	ifp->if_softc = sc;
96	if_initname(ifp, discname, unit);
97	ifp->if_mtu = DSMTU;
98	/*
99	 * IFF_LOOPBACK should not be removed from disc's flags because
100	 * it controls what PF-specific routes are magically added when
101	 * a network address is assigned to the interface.  Things just
102	 * won't work as intended w/o such routes because the output
103	 * interface selection for a packet is totally route-driven.
104	 * A valid alternative to IFF_LOOPBACK can be IFF_BROADCAST or
105	 * IFF_POINTOPOINT, but it would result in different properties
106	 * of the interface.
107	 */
108	ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
109	ifp->if_drv_flags = IFF_DRV_RUNNING;
110	ifp->if_ioctl = discioctl;
111	ifp->if_output = discoutput;
112	ifp->if_hdrlen = 0;
113	ifp->if_addrlen = 0;
114	ifp->if_snd.ifq_maxlen = 20;
115	if_attach(ifp);
116	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
117
118	return (0);
119}
120
121static void
122disc_clone_destroy(struct ifnet *ifp)
123{
124	struct disc_softc	*sc;
125
126	sc = ifp->if_softc;
127
128	bpfdetach(ifp);
129	if_detach(ifp);
130	if_free(ifp);
131
132	free(sc, M_DISC);
133}
134
135static void
136vnet_disc_init(const void *unused __unused)
137{
138
139	V_disc_cloner = if_clone_simple(discname, disc_clone_create,
140	    disc_clone_destroy, 0);
141}
142VNET_SYSINIT(vnet_disc_init, SI_SUB_PSEUDO, SI_ORDER_ANY,
143    vnet_disc_init, NULL);
144
145static void
146vnet_disc_uninit(const void *unused __unused)
147{
148
149	if_clone_detach(V_disc_cloner);
150}
151VNET_SYSUNINIT(vnet_disc_uninit, SI_SUB_INIT_IF, SI_ORDER_ANY,
152    vnet_disc_uninit, NULL);
153
154static int
155disc_modevent(module_t mod, int type, void *data)
156{
157
158	switch (type) {
159	case MOD_LOAD:
160	case MOD_UNLOAD:
161		break;
162	default:
163		return (EOPNOTSUPP);
164	}
165	return (0);
166}
167
168static moduledata_t disc_mod = {
169	"if_disc",
170	disc_modevent,
171	NULL
172};
173
174DECLARE_MODULE(if_disc, disc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
175
176static int
177discoutput(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
178    struct route *ro)
179{
180	u_int32_t af;
181
182	M_ASSERTPKTHDR(m);
183
184	/* BPF writes need to be handled specially. */
185	if (dst->sa_family == AF_UNSPEC)
186		bcopy(dst->sa_data, &af, sizeof(af));
187	else
188		af = dst->sa_family;
189
190	if (bpf_peers_present(ifp->if_bpf))
191		bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
192
193	m->m_pkthdr.rcvif = ifp;
194
195	if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
196	if_inc_counter(ifp, IFCOUNTER_OBYTES, m->m_pkthdr.len);
197
198	m_freem(m);
199	return (0);
200}
201
202/*
203 * Process an ioctl request.
204 */
205static int
206discioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
207{
208	struct ifreq *ifr = (struct ifreq *)data;
209	int error = 0;
210
211	switch (cmd) {
212	case SIOCSIFADDR:
213		ifp->if_flags |= IFF_UP;
214
215		/*
216		 * Everything else is done at a higher level.
217		 */
218		break;
219	case SIOCADDMULTI:
220	case SIOCDELMULTI:
221		if (ifr == NULL) {
222			error = EAFNOSUPPORT;		/* XXX */
223			break;
224		}
225		switch (ifr->ifr_addr.sa_family) {
226#ifdef INET
227		case AF_INET:
228			break;
229#endif
230#ifdef INET6
231		case AF_INET6:
232			break;
233#endif
234		default:
235			error = EAFNOSUPPORT;
236			break;
237		}
238		break;
239	case SIOCSIFMTU:
240		ifp->if_mtu = ifr->ifr_mtu;
241		break;
242	default:
243		error = EINVAL;
244	}
245	return (error);
246}
247