if_fake.c   [plain text]

/*
 * Copyright (c) 2015-2017 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

/*
 * if_fake.c
 * - fake network interface used for testing
 * - "feth" (e.g. "feth0", "feth1") is a virtual ethernet interface that allows
 *   two instances to have their output/input paths "crossed-over" so that
 *   output on one is input on the other
 */

/*
 * Modification History:
 *
 * September 9, 2015	Dieter Siegmund (dieter@apple.com)
 * - created
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/kern_event.h>
#include <sys/mcache.h>
#include <sys/syslog.h>

#include <net/bpf.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_vlan_var.h>
#include <net/if_fake_var.h>
#include <net/if_arp.h>
#include <net/if_dl.h>
#include <net/if_ether.h>
#include <net/if_types.h>
#include <libkern/OSAtomic.h>

#include <net/dlil.h>

#include <net/kpi_interface.h>
#include <net/kpi_protocol.h>

#include <kern/locks.h>

#ifdef INET
#include <netinet/in.h>
#include <netinet/if_ether.h>
#endif

#include <net/if_media.h>
#include <net/ether_if_module.h>

#define FAKE_ETHER_NAME		"feth"

SYSCTL_DECL(_net_link);
SYSCTL_NODE(_net_link, OID_AUTO, fake, CTLFLAG_RW|CTLFLAG_LOCKED, 0,
	"Fake interface");

static int if_fake_txstart = 1;
SYSCTL_INT(_net_link_fake, OID_AUTO, txstart, CTLFLAG_RW | CTLFLAG_LOCKED,
	&if_fake_txstart, 0, "Fake interface TXSTART mode");

static int if_fake_hwcsum = 0;
SYSCTL_INT(_net_link_fake, OID_AUTO, hwcsum, CTLFLAG_RW | CTLFLAG_LOCKED,
	&if_fake_hwcsum, 0, "Fake interface simulate hardware checksum");

static int if_fake_nxattach = 0;
SYSCTL_INT(_net_link_fake, OID_AUTO, nxattach, CTLFLAG_RW | CTLFLAG_LOCKED,
	&if_fake_nxattach, 0, "Fake interface auto-attach nexus");

static int if_fake_bsd_mode = 1;
SYSCTL_INT(_net_link_fake, OID_AUTO, bsd_mode, CTLFLAG_RW | CTLFLAG_LOCKED,
	&if_fake_bsd_mode, 0, "Fake interface attach as BSD interface");

static int if_fake_debug = 0;
SYSCTL_INT(_net_link_fake, OID_AUTO, debug, CTLFLAG_RW | CTLFLAG_LOCKED,
	&if_fake_debug, 0, "Fake interface debug logs");

/**
 ** virtual ethernet structures, types
 **/

typedef uint16_t	iff_flags_t;
#define IFF_FLAGS_HWCSUM		0x0001
#define IFF_FLAGS_BSD_MODE		0x0002
#define IFF_FLAGS_DETACHING		0x0004


struct if_fake {
	char			iff_name[IFNAMSIZ]; /* our unique id */
	ifnet_t			iff_ifp;
	iff_flags_t		iff_flags;
	uint32_t		iff_retain_count;
	ifnet_t			iff_peer;	/* the other end */
	int			iff_media_current;
	int			iff_media_active;
	uint32_t		iff_media_count;
	int			iff_media_list[IF_FAKE_MEDIA_LIST_MAX];
	struct mbuf *		iff_pending_tx_packet;
	boolean_t		iff_start_busy;
};

typedef struct if_fake * if_fake_ref;

static if_fake_ref
ifnet_get_if_fake(ifnet_t ifp);

#define FETH_DPRINTF(fmt, ...)					\
	{ if (if_fake_debug != 0) printf("%s " fmt, __func__, ## __VA_ARGS__); }

static inline boolean_t
feth_in_bsd_mode(if_fake_ref fakeif)
{
	return ((fakeif->iff_flags & IFF_FLAGS_BSD_MODE) != 0);
}

static inline void
feth_set_detaching(if_fake_ref fakeif)
{
	fakeif->iff_flags |= IFF_FLAGS_DETACHING;
}

static inline boolean_t
feth_is_detaching(if_fake_ref fakeif)
{
	return ((fakeif->iff_flags & IFF_FLAGS_DETACHING) != 0);
}


#define M_FAKE 		M_DEVBUF

static	int feth_clone_create(struct if_clone *, u_int32_t, void *);
static	int feth_clone_destroy(ifnet_t);
static	int feth_output(ifnet_t ifp, struct mbuf *m);
static	void feth_start(ifnet_t ifp);
static	int feth_ioctl(ifnet_t ifp, u_long cmd, void * addr);
static 	int feth_config(ifnet_t ifp, ifnet_t peer);
static	void feth_if_free(ifnet_t ifp);
static	void feth_ifnet_set_attrs(if_fake_ref fakeif, ifnet_t ifp);
static	void feth_free(if_fake_ref fakeif);

static struct if_clone
feth_cloner = IF_CLONE_INITIALIZER(FAKE_ETHER_NAME,
				   feth_clone_create, 
				   feth_clone_destroy, 
				   0, 
				   IF_MAXUNIT);
static	void interface_link_event(ifnet_t ifp, u_int32_t event_code);

/* some media words to pretend to be ethernet */
static int default_media_words[] = {
	IFM_MAKEWORD(IFM_ETHER, 0, 0, 0),
	IFM_MAKEWORD(IFM_ETHER, IFM_10G_T, IFM_FDX, 0),
	IFM_MAKEWORD(IFM_ETHER, IFM_2500_T, IFM_FDX, 0),
	IFM_MAKEWORD(IFM_ETHER, IFM_5000_T, IFM_FDX, 0),
};
#define default_media_words_count (sizeof(default_media_words)		\
				   / sizeof (default_media_words[0]))

/**
 ** veth locks
 **/
static inline lck_grp_t *
my_lck_grp_alloc_init(const char * grp_name)
{
	lck_grp_t *		grp;
	lck_grp_attr_t *	grp_attrs;
    
	grp_attrs = lck_grp_attr_alloc_init();
	grp = lck_grp_alloc_init(grp_name, grp_attrs);
	lck_grp_attr_free(grp_attrs);
	return (grp);
}

static inline lck_mtx_t *
my_lck_mtx_alloc_init(lck_grp_t * lck_grp)
{
	lck_attr_t * 	lck_attrs;
	lck_mtx_t *		lck_mtx;

	lck_attrs = lck_attr_alloc_init();
	lck_mtx = lck_mtx_alloc_init(lck_grp, lck_attrs);
	lck_attr_free(lck_attrs);
	return (lck_mtx);
}

static lck_mtx_t * 	feth_lck_mtx;

static inline void
feth_lock_init(void)
{
	lck_grp_t *		feth_lck_grp;

	feth_lck_grp = my_lck_grp_alloc_init("fake");
	feth_lck_mtx = my_lck_mtx_alloc_init(feth_lck_grp);
}

#if 0
static inline void
feth_assert_lock_not_held(void)
{
	LCK_MTX_ASSERT(feth_lck_mtx, LCK_MTX_ASSERT_NOTOWNED);
	return;
}
#endif

static inline void
feth_lock(void)
{
	lck_mtx_lock(feth_lck_mtx);
	return;
}

static inline void
feth_unlock(void)
{
	lck_mtx_unlock(feth_lck_mtx);
	return;
}

static inline int
feth_max_mtu(void)
{
	if (njcl > 0) {
		return (M16KCLBYTES - ETHER_HDR_LEN);
	}
	return (MBIGCLBYTES - ETHER_HDR_LEN);
}

static void
feth_free(if_fake_ref fakeif)
{
	assert(fakeif->iff_retain_count == 0);
	if (feth_in_bsd_mode(fakeif)) {
		if (fakeif->iff_pending_tx_packet) {
			m_freem(fakeif->iff_pending_tx_packet);
		}
	}

	FETH_DPRINTF("%s\n", fakeif->iff_name);
	FREE(fakeif, M_FAKE);
}

static void
feth_release(if_fake_ref fakeif)
{
	u_int32_t		old_retain_count;

	old_retain_count = OSDecrementAtomic(&fakeif->iff_retain_count);
	switch (old_retain_count) {
	case 0:
		assert(old_retain_count != 0);
		break;
	case 1:
		feth_free(fakeif);
		break;
	default:
		break;
	}
	return;
}


/**
 ** feth interface routines
 **/
static void
feth_ifnet_set_attrs(if_fake_ref fakeif, ifnet_t ifp)
{
	(void)ifnet_set_capabilities_enabled(ifp, 0, -1);
	ifnet_set_addrlen(ifp, ETHER_ADDR_LEN);
	ifnet_set_baudrate(ifp, 0);
	ifnet_set_mtu(ifp, ETHERMTU);
	ifnet_set_flags(ifp,
			IFF_BROADCAST | IFF_MULTICAST | IFF_SIMPLEX,
			0xffff);
	ifnet_set_hdrlen(ifp, sizeof(struct ether_header));
	if ((fakeif->iff_flags & IFF_FLAGS_HWCSUM) != 0) {
		ifnet_set_offload(ifp,
		    IFNET_CSUM_IP | IFNET_CSUM_TCP | IFNET_CSUM_UDP |
		    IFNET_CSUM_TCPIPV6 | IFNET_CSUM_UDPIPV6);
	} else {
		ifnet_set_offload(ifp, 0);
	}
}

static void
interface_link_event(ifnet_t ifp, u_int32_t event_code)
{
	struct {
		struct kern_event_msg	header;
		u_int32_t		unit;
		char			if_name[IFNAMSIZ];
	} event;

	bzero(&event, sizeof(event));
	event.header.total_size    = sizeof(event);
	event.header.vendor_code   = KEV_VENDOR_APPLE;
	event.header.kev_class     = KEV_NETWORK_CLASS;
	event.header.kev_subclass  = KEV_DL_SUBCLASS;
	event.header.event_code    = event_code;
	event.header.event_data[0] = ifnet_family(ifp);
	event.unit                 = (u_int32_t) ifnet_unit(ifp);
	strlcpy(event.if_name, ifnet_name(ifp), IFNAMSIZ);
	ifnet_event(ifp, &event.header);
	return;
}

static if_fake_ref
ifnet_get_if_fake(ifnet_t ifp)
{
	return ((if_fake_ref)ifnet_softc(ifp));
}

static int
feth_clone_create(struct if_clone *ifc, u_int32_t unit, __unused void *params)
{
	int				error;
	if_fake_ref			fakeif;
	struct ifnet_init_eparams	feth_init;
	ifnet_t				ifp;
	uint8_t				mac_address[ETHER_ADDR_LEN];

	fakeif = _MALLOC(sizeof(struct if_fake), M_FAKE, M_WAITOK | M_ZERO);
	if (fakeif == NULL) {
		return ENOBUFS;
	}
	fakeif->iff_retain_count = 1;
#define FAKE_ETHER_NAME_LEN	(sizeof(FAKE_ETHER_NAME) - 1)
	_CASSERT(FAKE_ETHER_NAME_LEN == 4);
	bcopy(FAKE_ETHER_NAME, mac_address, FAKE_ETHER_NAME_LEN);
	mac_address[ETHER_ADDR_LEN - 2] = (unit & 0xff00) >> 8;
	mac_address[ETHER_ADDR_LEN - 1] = unit & 0xff;
	if (if_fake_bsd_mode != 0) {
		fakeif->iff_flags |= IFF_FLAGS_BSD_MODE;
	}
	if (if_fake_hwcsum != 0) {
		fakeif->iff_flags |= IFF_FLAGS_HWCSUM;
	}

	/* use the interface name as the unique id for ifp recycle */
	if ((unsigned int)
	    snprintf(fakeif->iff_name, sizeof(fakeif->iff_name), "%s%d",
		     ifc->ifc_name, unit) >= sizeof(fakeif->iff_name)) {
		feth_release(fakeif);
		return (EINVAL);
	}
	bzero(&feth_init, sizeof(feth_init));
	feth_init.ver = IFNET_INIT_CURRENT_VERSION;
	feth_init.len = sizeof (feth_init);
	if (feth_in_bsd_mode(fakeif)) {
		if (if_fake_txstart != 0) {
			feth_init.start = feth_start;
		} else {
			feth_init.flags |= IFNET_INIT_LEGACY;
			feth_init.output = feth_output;
		}
	}
	if (if_fake_nxattach == 0) {
		feth_init.flags |= IFNET_INIT_NX_NOAUTO;
	}
	feth_init.uniqueid = fakeif->iff_name;
	feth_init.uniqueid_len = strlen(fakeif->iff_name);
	feth_init.name = ifc->ifc_name;
	feth_init.unit = unit;
	feth_init.family = IFNET_FAMILY_ETHERNET;
	feth_init.type = IFT_ETHER;
	feth_init.demux = ether_demux;
	feth_init.add_proto = ether_add_proto;
	feth_init.del_proto = ether_del_proto;
	feth_init.check_multi = ether_check_multi;
	feth_init.framer_extended = ether_frameout_extended;
	feth_init.softc = fakeif;
	feth_init.ioctl = feth_ioctl;
	feth_init.set_bpf_tap = NULL;
	feth_init.detach = feth_if_free;
	feth_init.broadcast_addr = etherbroadcastaddr;
	feth_init.broadcast_len = ETHER_ADDR_LEN;
	if (feth_in_bsd_mode(fakeif)) {
		error = ifnet_allocate_extended(&feth_init, &ifp);
		if (error) {
			feth_release(fakeif);
			return (error);
		}
		feth_ifnet_set_attrs(fakeif, ifp);
	}
	fakeif->iff_media_count = default_media_words_count;
	bcopy(default_media_words, fakeif->iff_media_list,
	      sizeof(default_media_words));
	if (feth_in_bsd_mode(fakeif)) {
		error = ifnet_attach(ifp, NULL);
		if (error) {
			ifnet_release(ifp);
			feth_release(fakeif);
			return (error);
		}
		fakeif->iff_ifp = ifp;
	}

	ifnet_set_lladdr(ifp, mac_address, sizeof(mac_address));
	
	/* attach as ethernet */
	bpfattach(ifp, DLT_EN10MB, sizeof(struct ether_header));
	return (0);
}

static int
feth_clone_destroy(ifnet_t ifp)
{
	if_fake_ref	fakeif;

	feth_lock();
	fakeif = ifnet_get_if_fake(ifp);
	if (fakeif == NULL || feth_is_detaching(fakeif)) {
		feth_unlock();
		return (0);
	}
	feth_set_detaching(fakeif);
	feth_unlock();

	feth_config(ifp, NULL);
	ifnet_detach(ifp);
	return 0;
}

static void
feth_enqueue_input(ifnet_t ifp, struct mbuf * m)
{
	struct ifnet_stat_increment_param stats = {};

	stats.packets_in = 1;
	stats.bytes_in = (uint32_t)mbuf_pkthdr_len(m) + ETHER_HDR_LEN;
	ifnet_input(ifp, m, &stats);
}

static struct mbuf *
copy_mbuf(struct mbuf *m)
{
	struct mbuf *	copy_m;
	uint32_t	pkt_len;
	uint32_t	offset;

	if ((m->m_flags & M_PKTHDR) == 0) {
		return (NULL);
	}
	pkt_len = m->m_pkthdr.len;
	MGETHDR(copy_m, M_DONTWAIT, MT_DATA);
	if (copy_m == NULL) {
		goto failed;
	}
	if (pkt_len > MHLEN) {
		if (pkt_len <= MCLBYTES) {
			MCLGET(copy_m, M_DONTWAIT);
		} else if (pkt_len <= MBIGCLBYTES) {
			copy_m = m_mbigget(copy_m, M_DONTWAIT);
		} else if (pkt_len <= M16KCLBYTES && njcl > 0) {
			copy_m = m_m16kget(copy_m, M_DONTWAIT);
		} else {
			printf("if_fake: copy_mbuf(): packet too large %d\n",
			       pkt_len);
			goto failed;
		}
		if (copy_m == NULL || (copy_m->m_flags & M_EXT) == 0) {
			goto failed;
		}
	}
	mbuf_setlen(copy_m, pkt_len);
	copy_m->m_pkthdr.len = pkt_len;
	offset = 0;
	while (m != NULL && offset < pkt_len) {
		uint32_t	frag_len;

		frag_len = m->m_len;
		if (frag_len > (pkt_len - offset)) {
			printf("if_fake_: Large mbuf fragment %d > %d\n",
			       frag_len, (pkt_len - offset));
			goto failed;
		}
		m_copydata(m, 0, frag_len, mtod(copy_m, void *) + offset);
		offset += frag_len;
		m = m->m_next;
	}
	return (copy_m);

 failed:
	if (copy_m != NULL) {
		m_freem(copy_m);
	}
	return (NULL);
}

static void
feth_output_common(ifnet_t ifp, struct mbuf * m, ifnet_t peer,
		   iff_flags_t flags)
{
	void *		frame_header;

	frame_header = mbuf_data(m);
	if ((flags & IFF_FLAGS_HWCSUM) != 0) {
		m->m_pkthdr.csum_data = 0xffff;
		m->m_pkthdr.csum_flags =
			CSUM_DATA_VALID | CSUM_PSEUDO_HDR |
			CSUM_IP_CHECKED | CSUM_IP_VALID;
	}

	(void)ifnet_stat_increment_out(ifp, 1, m->m_pkthdr.len, 0);
	bpf_tap_out(ifp, DLT_EN10MB, m, NULL, 0);

	(void)mbuf_pkthdr_setrcvif(m, peer);
	mbuf_pkthdr_setheader(m, frame_header);
	mbuf_pkthdr_adjustlen(m, - ETHER_HDR_LEN);
	(void)mbuf_setdata(m, (char *)mbuf_data(m) + ETHER_HDR_LEN,
			   mbuf_len(m) - ETHER_HDR_LEN);
	bpf_tap_in(peer, DLT_EN10MB, m, frame_header,
		   sizeof(struct ether_header));
	feth_enqueue_input(peer, m);
}

static void
feth_start(ifnet_t ifp)
{
	struct mbuf *	copy_m = NULL;
	if_fake_ref	fakeif;
	iff_flags_t	flags = 0;
	ifnet_t	peer = NULL;
	struct mbuf *	m;
	struct mbuf *	save_m;

	feth_lock();
	fakeif = ifnet_get_if_fake(ifp);
	if (fakeif->iff_start_busy) {
		feth_unlock();
		printf("if_fake: start is busy\n");
		return;
	}
	if (fakeif != NULL) {
		peer = fakeif->iff_peer;
		flags = fakeif->iff_flags;
	}

	/* check for pending TX */
	m = fakeif->iff_pending_tx_packet;
	if (m != NULL) {
		if (peer != NULL) {
			copy_m = copy_mbuf(m);
			if (copy_m == NULL) {
				feth_unlock();
				return;
			}
		}
		fakeif->iff_pending_tx_packet = NULL;
		m_freem(m);
		m = NULL;
	}
	fakeif->iff_start_busy = TRUE;
	feth_unlock();
	save_m = NULL;
	for (;;) {
		if (copy_m != NULL) {
			assert(peer != NULL);
			feth_output_common(ifp, copy_m, peer, flags);
			copy_m = NULL;
		}
		if (ifnet_dequeue(ifp, &m) != 0) {
			break;
		}
		if (peer == NULL) {
			m_freem(m);
		} else {
			copy_m = copy_mbuf(m);
			if (copy_m == NULL) {
				save_m = m;
				break;
			}
			m_freem(m);
		}
	}
	peer = NULL;
	feth_lock();
	fakeif = ifnet_get_if_fake(ifp);
	if (fakeif != NULL) {
		fakeif->iff_start_busy = FALSE;
		if (save_m != NULL && fakeif->iff_peer != NULL) {
			/* save it for next time */
			fakeif->iff_pending_tx_packet = save_m;
			save_m = NULL;
		}
	}
	feth_unlock();
	if (save_m != NULL) {
		/* didn't save packet, so free it */
		m_freem(save_m);
	}
}

static int
feth_output(ifnet_t ifp, struct mbuf * m)
{
	struct mbuf *		copy_m;
	if_fake_ref		fakeif;
	iff_flags_t		flags;
	ifnet_t		peer = NULL;

	if (m == NULL) {
		return (0);
	}
	copy_m = copy_mbuf(m);
	m_freem(m);
	m = NULL;
	if (copy_m == NULL) {
		/* count this as an output error */
		ifnet_stat_increment_out(ifp, 0, 0, 1);
		return (0);
	}
	feth_lock();
	fakeif = ifnet_get_if_fake(ifp);
	if (fakeif != NULL) {
		peer = fakeif->iff_peer;
		flags = fakeif->iff_flags;
	}
	feth_unlock();
	if (peer == NULL) {
		m_freem(copy_m);
		ifnet_stat_increment_out(ifp, 0, 0, 1);
		return (0);
	}
	feth_output_common(ifp, copy_m, peer, flags);
	return (0);
}

static int
feth_config(ifnet_t ifp, ifnet_t peer)
{
	int		connected = FALSE;
	int		disconnected = FALSE;
	int		error = 0;
	if_fake_ref 	fakeif = NULL;

	feth_lock();
	fakeif = ifnet_get_if_fake(ifp);
	if (fakeif == NULL) {
		error = EINVAL;
		goto done;
	}
	if (peer != NULL) {
		/* connect to peer */
		if_fake_ref	peer_fakeif;

		peer_fakeif = ifnet_get_if_fake(peer);
		if (peer_fakeif == NULL) {
			error = EINVAL;
			goto done;
		}
		if (feth_is_detaching(fakeif) ||
		    feth_is_detaching(peer_fakeif) ||
		    peer_fakeif->iff_peer != NULL ||
		    fakeif->iff_peer != NULL) {
			error = EBUSY;
			goto done;
		}
		fakeif->iff_peer = peer;
		peer_fakeif->iff_peer = ifp;
		connected = TRUE;
	}
	else if (fakeif->iff_peer != NULL) {
		/* disconnect from peer */
		if_fake_ref	peer_fakeif;

		peer = fakeif->iff_peer;
		peer_fakeif = ifnet_get_if_fake(peer);
		if (peer_fakeif == NULL) {
			/* should not happen */
			error = EINVAL;
			goto done;
		}
		fakeif->iff_peer = NULL;
		peer_fakeif->iff_peer = NULL;
		disconnected = TRUE;
	}

 done:
	feth_unlock();

	/* generate link status event if we connect or disconnect */
	if (connected) {
		ifnet_set_flags(ifp, IFF_RUNNING, IFF_RUNNING);
		ifnet_set_flags(peer, IFF_RUNNING, IFF_RUNNING);
		interface_link_event(ifp, KEV_DL_LINK_ON);
		interface_link_event(peer, KEV_DL_LINK_ON);
	}
	else if (disconnected) {
		ifnet_set_flags(ifp, 0, IFF_RUNNING);
		ifnet_set_flags(peer, 0, IFF_RUNNING);
		interface_link_event(ifp, KEV_DL_LINK_OFF);
		interface_link_event(peer, KEV_DL_LINK_OFF);
	}
	return (error);
}

static int
feth_set_media(ifnet_t ifp, struct if_fake_request * iffr)
{
	if_fake_ref	fakeif;
	int		error;

	if (iffr->iffr_media.iffm_count > IF_FAKE_MEDIA_LIST_MAX) {
		/* list is too long */
		return (EINVAL);
	}
	feth_lock();
	fakeif = ifnet_get_if_fake(ifp);
	if (fakeif == NULL) {
		error = EINVAL;
		goto done;
	}
	fakeif->iff_media_count = iffr->iffr_media.iffm_count;
	bcopy(iffr->iffr_media.iffm_list, fakeif->iff_media_list,
	      iffr->iffr_media.iffm_count * sizeof(fakeif->iff_media_list[0]));
#if 0
	/* XXX: "auto-negotiate" active with peer? */
	/* generate link status event? */
	fakeif->iff_media_current = iffr->iffr_media.iffm_current;
#endif
	error = 0;
 done:
	feth_unlock();
	return (error);
}

static int
if_fake_request_copyin(user_addr_t user_addr, 
		       struct if_fake_request *iffr, u_int32_t len)
{
	int	error;

	if (user_addr == USER_ADDR_NULL || len < sizeof(*iffr)) {
		error = EINVAL;
		goto done;
	}
	error = copyin(user_addr, iffr, sizeof(*iffr));
	if (error != 0) {
		goto done;
	}
	if (iffr->iffr_reserved[0] != 0 || iffr->iffr_reserved[1] != 0 ||
	    iffr->iffr_reserved[2] != 0 || iffr->iffr_reserved[3] != 0) {
		error = EINVAL;
		goto done;
	}
 done:
	return (error);
}

static int
feth_set_drvspec(ifnet_t ifp, uint32_t cmd, u_int32_t len,
		 user_addr_t user_addr)
{
	int			error;
	struct if_fake_request	iffr;
	ifnet_t			peer;

	switch (cmd) {
	case IF_FAKE_S_CMD_SET_PEER:
		error = if_fake_request_copyin(user_addr, &iffr, len);
		if (error != 0) {
			break;
		}
		if (iffr.iffr_peer_name[0] == '\0') {
			error = feth_config(ifp, NULL);
			break;
		}

		/* ensure nul termination */
		iffr.iffr_peer_name[IFNAMSIZ - 1] = '\0';
		peer = ifunit(iffr.iffr_peer_name);
		if (peer == NULL) {
			error = ENXIO;
			break;
		}
		if (ifnet_type(peer) != IFT_ETHER) {
			error = EINVAL;
			break;
		}
		if (strcmp(ifnet_name(peer), FAKE_ETHER_NAME) != 0) {
			error = EINVAL;
			break;
		}
		error = feth_config(ifp, peer);
		break;
	case IF_FAKE_S_CMD_SET_MEDIA:
		error = if_fake_request_copyin(user_addr, &iffr, len);
		if (error != 0) {
			break;
		}
		error = feth_set_media(ifp, &iffr);
		break;
	default:
		error = EOPNOTSUPP;
		break;
	}
	return (error);
}

static int
feth_get_drvspec(ifnet_t ifp, u_int32_t cmd, u_int32_t len,
		 user_addr_t user_addr)
{
	int			error = EOPNOTSUPP;
	if_fake_ref		fakeif;
	struct if_fake_request	iffr;
	ifnet_t			peer;

	switch (cmd) {
	case IF_FAKE_G_CMD_GET_PEER:
		if (len < sizeof(iffr)) {
			error = EINVAL;
			break;
		}
		feth_lock();
		fakeif = (if_fake_ref)ifnet_softc(ifp);
		if (fakeif == NULL) {
			feth_unlock();
			error = EOPNOTSUPP;
			break;
		}
		peer = fakeif->iff_peer;
		feth_unlock();
		bzero(&iffr, sizeof(iffr));
		if (peer != NULL) {
			strlcpy(iffr.iffr_peer_name,
				if_name(peer),
				sizeof(iffr.iffr_peer_name));
		}
		error = copyout(&iffr, user_addr, sizeof(iffr));
		break;
	default:
		break;
	}
	return (error);
}

union ifdrvu {
	struct ifdrv32 	*ifdrvu_32;
	struct ifdrv64 	*ifdrvu_64;
	void		*ifdrvu_p;		
};

static int
feth_ioctl(ifnet_t ifp, u_long cmd, void * data)
{
	unsigned int		count;
	struct ifdevmtu *	devmtu_p;
	union ifdrvu		drv;
	uint32_t		drv_cmd;
	uint32_t		drv_len;
	boolean_t		drv_set_command = FALSE;
	int 			error = 0;
	struct ifmediareq *	ifmr;
	struct ifreq *		ifr;
	if_fake_ref		fakeif;
	int			status;
	user_addr_t		user_addr;

	ifr = (struct ifreq *)data;
	switch (cmd) {
	case SIOCSIFADDR:
		ifnet_set_flags(ifp, IFF_UP, IFF_UP);
		break;

	case SIOCGIFMEDIA32:
	case SIOCGIFMEDIA64:
		feth_lock();
		fakeif = (if_fake_ref)ifnet_softc(ifp);
		if (fakeif == NULL) {
			feth_unlock();
			return (EOPNOTSUPP);
		}
		status = (fakeif->iff_peer != NULL)
		    ? (IFM_AVALID | IFM_ACTIVE) : IFM_AVALID;
		ifmr = (struct ifmediareq *)data;
		user_addr = (cmd == SIOCGIFMEDIA64) ?
			((struct ifmediareq64 *)ifmr)->ifmu_ulist :
			CAST_USER_ADDR_T(((struct ifmediareq32 *)ifmr)->ifmu_ulist);
		count = ifmr->ifm_count;
		ifmr->ifm_active = IFM_ETHER;
		ifmr->ifm_current = IFM_ETHER;
		ifmr->ifm_mask = 0;
		ifmr->ifm_status = status;
		if (user_addr == USER_ADDR_NULL) {
			ifmr->ifm_count = fakeif->iff_media_count;
		}
		else if (count > 0) {
			if (count > fakeif->iff_media_count) {
				count = fakeif->iff_media_count;
			}
			ifmr->ifm_count = count;
			error = copyout(&fakeif->iff_media_list, user_addr,
					count * sizeof(int));
		}
		feth_unlock();
		break;

	case SIOCGIFDEVMTU:
		devmtu_p = &ifr->ifr_devmtu;
		devmtu_p->ifdm_current = ifnet_mtu(ifp);
		devmtu_p->ifdm_max = feth_max_mtu();
		devmtu_p->ifdm_min = IF_MINMTU;
		break;

	case SIOCSIFMTU:
		if (ifr->ifr_mtu > feth_max_mtu() || ifr->ifr_mtu < IF_MINMTU) {
			error = EINVAL;
		} else {
			error = ifnet_set_mtu(ifp, ifr->ifr_mtu);
		}
		break;

	case SIOCSDRVSPEC32:
	case SIOCSDRVSPEC64:
		error = proc_suser(current_proc());
		if (error != 0) {
			break;
		}
		drv_set_command = TRUE;
		/* FALL THROUGH */
	case SIOCGDRVSPEC32:
	case SIOCGDRVSPEC64:
		drv.ifdrvu_p = data;
		if (cmd == SIOCGDRVSPEC32 || cmd == SIOCSDRVSPEC32) {
			drv_cmd = drv.ifdrvu_32->ifd_cmd;
			drv_len = drv.ifdrvu_32->ifd_len;
			user_addr = CAST_USER_ADDR_T(drv.ifdrvu_32->ifd_data);

		} else {
			drv_cmd = drv.ifdrvu_64->ifd_cmd;
			drv_len = drv.ifdrvu_64->ifd_len;
			user_addr = drv.ifdrvu_64->ifd_data;
		}
		if (drv_set_command) {
			error = feth_set_drvspec(ifp, drv_cmd, drv_len,
						 user_addr);
		} else {
			error = feth_get_drvspec(ifp, drv_cmd, drv_len,
						 user_addr);
		}
		break;

	case SIOCSIFLLADDR:
		error = ifnet_set_lladdr(ifp, ifr->ifr_addr.sa_data,
		    ifr->ifr_addr.sa_len);
		break;

	case SIOCSIFFLAGS:
		error = 0;
		break;

	case SIOCADDMULTI:
	case SIOCDELMULTI:
		error = 0;
		break;
	default:
		error = EOPNOTSUPP;
		break;
	}
	return error;
}

static void 
feth_if_free(ifnet_t ifp)
{
	if_fake_ref		fakeif;

	if (ifp == NULL) {
		return;
	}
	feth_lock();
	fakeif = ifnet_get_if_fake(ifp);
	if (fakeif == NULL) {
		feth_unlock();
		return;
	}
	ifp->if_softc = NULL;
	feth_unlock();
	feth_release(fakeif);
	ifnet_release(ifp);
	return;
}

__private_extern__ void
if_fake_init(void)
{
	int error;

	feth_lock_init();
	error = if_clone_attach(&feth_cloner);
	if (error != 0) {
		return;
	}
	return;
}