/*	$NetBSD: link_proto.c,v 1.40 2021/12/31 14:25:24 riastradh Exp $	*/

/*-
 * Copyright (c) 1982, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)uipc_proto.c	8.2 (Berkeley) 2/14/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: link_proto.c,v 1.40 2021/12/31 14:25:24 riastradh Exp $");

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/mbuf.h>
#include <sys/un.h>
#include <sys/socketvar.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/raw_cb.h>
#include <net/route.h>

static int sockaddr_dl_cmp(const struct sockaddr *, const struct sockaddr *);
static int link_attach(struct socket *, int);
static void link_detach(struct socket *);
static int link_accept(struct socket *, struct sockaddr *);
static int link_bind(struct socket *, struct sockaddr *, struct lwp *);
static int link_listen(struct socket *, struct lwp *);
static int link_connect(struct socket *, struct sockaddr *, struct lwp *);
static int link_connect2(struct socket *, struct socket *);
static int link_disconnect(struct socket *);
static int link_shutdown(struct socket *);
static int link_abort(struct socket *);
static int link_ioctl(struct socket *, u_long, void *, struct ifnet *);
static int link_stat(struct socket *, struct stat *);
static int link_peeraddr(struct socket *, struct sockaddr *);
static int link_sockaddr(struct socket *, struct sockaddr *);
static int link_rcvd(struct socket *, int, struct lwp *);
static int link_recvoob(struct socket *, struct mbuf *, int);
static int link_send(struct socket *, struct mbuf *, struct sockaddr *,
    struct mbuf *, struct lwp *);
static int link_sendoob(struct socket *, struct mbuf *, struct mbuf *);
static int link_purgeif(struct socket *, struct ifnet *);
static void link_init(void);

/*
 * Definitions of protocols supported in the link-layer domain.
 */

DOMAIN_DEFINE(linkdomain);	/* forward define and add to link set */

static const struct pr_usrreqs link_usrreqs = {
	.pr_attach	= link_attach,
	.pr_detach	= link_detach,
	.pr_accept	= link_accept,
	.pr_bind	= link_bind,
	.pr_listen	= link_listen,
	.pr_connect	= link_connect,
	.pr_connect2	= link_connect2,
	.pr_disconnect	= link_disconnect,
	.pr_shutdown	= link_shutdown,
	.pr_abort	= link_abort,
	.pr_ioctl	= link_ioctl,
	.pr_stat	= link_stat,
	.pr_peeraddr	= link_peeraddr,
	.pr_sockaddr	= link_sockaddr,
	.pr_rcvd	= link_rcvd,
	.pr_recvoob	= link_recvoob,
	.pr_send	= link_send,
	.pr_sendoob	= link_sendoob,
	.pr_purgeif	= link_purgeif,
};

const struct protosw linksw[] = {
	{	.pr_type = SOCK_DGRAM,
		.pr_domain = &linkdomain,
		.pr_protocol = 0,	/* XXX */
		.pr_flags = PR_ATOMIC|PR_ADDR|PR_PURGEIF,
		.pr_input = NULL,
		.pr_ctlinput = NULL,
		.pr_ctloutput = NULL,
		.pr_usrreqs = &link_usrreqs,
		.pr_init = link_init,
	},
};

struct domain linkdomain = {
	.dom_family = AF_LINK,
	.dom_name = "link",
	.dom_externalize = NULL,
	.dom_dispose = NULL,
	.dom_protosw = linksw,
	.dom_protoswNPROTOSW = &linksw[__arraycount(linksw)],
	.dom_sockaddr_cmp = sockaddr_dl_cmp
};

static void
link_init(void)
{
	return;
}

static int
link_control(struct socket *so, unsigned long cmd, void *data,
    struct ifnet *ifp)
{
	int error, s;
	bool isactive, mkactive;
	struct if_laddrreq *iflr;
	union {
		struct sockaddr sa;
		struct sockaddr_dl sdl;
		struct sockaddr_storage ss;
	} u;
	struct ifaddr *ifa;
	const struct sockaddr_dl *asdl, *nsdl;
	struct psref psref;

	switch (cmd) {
	case SIOCALIFADDR:
	case SIOCDLIFADDR:
	case SIOCGLIFADDR:
		iflr = data;

		if (iflr->addr.ss_family != AF_LINK)
			return EINVAL;

		asdl = satocsdl(sstocsa(&iflr->addr));

		if (asdl->sdl_alen != ifp->if_addrlen)
			return EINVAL;

		if (sockaddr_dl_init(&u.sdl, sizeof(u.ss), ifp->if_index,
		    ifp->if_type, ifp->if_xname, strlen(ifp->if_xname),
		    CLLADDR(asdl), asdl->sdl_alen) == NULL)
			return EINVAL;

		if ((iflr->flags & IFLR_PREFIX) == 0)
			;
		else if (iflr->prefixlen != NBBY * ifp->if_addrlen)
			return EINVAL;	/* XXX match with prefix */

		error = 0;

		s = pserialize_read_enter();
		IFADDR_READER_FOREACH(ifa, ifp) {
			if (sockaddr_cmp(&u.sa, ifa->ifa_addr) == 0) {
				ifa_acquire(ifa, &psref);
				break;
			}
		}
		pserialize_read_exit(s);

		switch (cmd) {
		case SIOCGLIFADDR:
			ifa_release(ifa, &psref);
			s = pserialize_read_enter();
			if ((iflr->flags & IFLR_PREFIX) == 0) {
				IFADDR_READER_FOREACH(ifa, ifp) {
					if (ifa->ifa_addr->sa_family == AF_LINK)
						break;
				}
			}
			if (ifa == NULL) {
				pserialize_read_exit(s);
				error = EADDRNOTAVAIL;
				break;
			}

			if (ifa == ifp->if_dl)
				iflr->flags = IFLR_ACTIVE;
			else
				iflr->flags = 0;

			if (ifa == ifp->if_hwdl)
				iflr->flags |= IFLR_FACTORY;

			sockaddr_copy(sstosa(&iflr->addr), sizeof(iflr->addr),
			    ifa->ifa_addr);
			pserialize_read_exit(s);
			ifa = NULL;

			break;
		case SIOCDLIFADDR:
			if (ifa == NULL)
				error = EADDRNOTAVAIL;
			else if (ifa == ifp->if_dl || ifa == ifp->if_hwdl)
				error = EBUSY;
			else {
				/* TBD routing socket */
				rt_addrmsg(RTM_DELETE, ifa);
				/* We need to release psref for ifa_remove */
				ifaref(ifa);
				ifa_release(ifa, &psref);
				ifa_remove(ifp, ifa);
				KASSERTMSG(ifa->ifa_refcnt == 1, "ifa_refcnt=%d",
				    ifa->ifa_refcnt);
				ifafree(ifa);
				ifa = NULL;
			}
			break;
		case SIOCALIFADDR:
			if (ifa == NULL) {
				ifa = if_dl_create(ifp, &nsdl);
				if (ifa == NULL) {
					error = ENOMEM;
					break;
				}
				ifa_acquire(ifa, &psref);
				sockaddr_copy(ifa->ifa_addr,
				    ifa->ifa_addr->sa_len, &u.sa);
				ifa_insert(ifp, ifa);
				rt_addrmsg(RTM_ADD, ifa);
			}

			mkactive = (iflr->flags & IFLR_ACTIVE) != 0;
			isactive = (ifa == ifp->if_dl);

			if (!isactive && mkactive) {
				if_activate_sadl(ifp, ifa, nsdl);
				rt_addrmsg(RTM_CHANGE, ifa);
				error = ENETRESET;
			}
			break;
		}
		ifa_release(ifa, &psref);
		if (error != ENETRESET)
			return error;
		else if ((ifp->if_flags & IFF_RUNNING) != 0 &&
		         ifp->if_init != NULL)
			return if_init(ifp);
		else
			return 0;
	default:
		return ENOTTY;
	}
}

static int
link_attach(struct socket *so, int proto)
{
	sosetlock(so);
	KASSERT(solocked(so));
	return 0;
}

static void
link_detach(struct socket *so)
{
	KASSERT(solocked(so));
	sofree(so);
}

static int
link_accept(struct socket *so, struct sockaddr *nam)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_bind(struct socket *so, struct sockaddr *nam, struct lwp *l)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_listen(struct socket *so, struct lwp *l)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_connect(struct socket *so, struct sockaddr *nam, struct lwp *l)
{
 	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_connect2(struct socket *so, struct socket *so2)
{
 	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_disconnect(struct socket *so)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_shutdown(struct socket *so)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_abort(struct socket *so)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_ioctl(struct socket *so, u_long cmd, void *nam, struct ifnet *ifp)
{
	return link_control(so, cmd, nam, ifp);
}

static int
link_stat(struct socket *so, struct stat *ub)
{
	KASSERT(solocked(so));

	return 0;
}

static int
link_peeraddr(struct socket *so, struct sockaddr *nam)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_sockaddr(struct socket *so, struct sockaddr *nam)
{
 	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_rcvd(struct socket *so, int flags, struct lwp *l)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_recvoob(struct socket *so, struct mbuf *m, int flags)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_send(struct socket *so, struct mbuf *m, struct sockaddr *nam,
    struct mbuf *control, struct lwp *l)
{
	KASSERT(solocked(so));

	return EOPNOTSUPP;
}

static int
link_sendoob(struct socket *so, struct mbuf *m, struct mbuf *control)
{
	KASSERT(solocked(so));

	m_freem(m);
	m_freem(control);

	return EOPNOTSUPP;
}

static int
link_purgeif(struct socket *so, struct ifnet *ifp)
{

	return EOPNOTSUPP;
}

/* Compare the field at byte offsets [fieldstart, fieldend) in
 * two memory regions, [l, l + llen) and [r, r + llen).
 */
static inline int
submemcmp(const void *l, const void *r,
    const uint_fast8_t llen, const uint_fast8_t rlen,
    const uint_fast8_t fieldstart, const uint_fast8_t fieldend)
{
	uint_fast8_t cmpend, minlen;
	const uint8_t *lb = l, *rb = r;
	int rc;

	minlen = MIN(llen, rlen);

	/* The field is missing from one region.  The shorter region is the
	 * lesser region.
	 */
	if (fieldstart >= minlen)
		return llen - rlen;

	/* Two empty, present fields are always equal. */
	if (fieldstart > fieldend)
		return 0;

	cmpend = MIN(fieldend, minlen);

	rc = memcmp(&lb[fieldstart], &rb[fieldstart], cmpend - fieldstart);

	if (rc != 0)
		return rc;
	/* If one or both fields are truncated, then the shorter is the lesser
	 * field.
	 */
	if (minlen < fieldend)
		return llen - rlen;
	/* Fields are full-length and equal.  The fields are equal. */
	return 0;
}

uint8_t
sockaddr_dl_measure(uint8_t namelen, uint8_t addrlen)
{
	return offsetof(struct sockaddr_dl, sdl_data[namelen + addrlen]);
}

struct sockaddr *
sockaddr_dl_alloc(uint16_t ifindex, uint8_t type,
    const void *name, uint8_t namelen, const void *addr, uint8_t addrlen,
    int flags)
{
	struct sockaddr *sa;
	socklen_t len;

	len = sockaddr_dl_measure(namelen, addrlen);
	sa = sockaddr_alloc(AF_LINK, len, flags);

	if (sa == NULL)
		return NULL;

	if (sockaddr_dl_init(satosdl(sa), len, ifindex, type, name, namelen,
	    addr, addrlen) == NULL) {
		sockaddr_free(sa);
		return NULL;
	}

	return sa;
}

struct sockaddr_dl *
sockaddr_dl_init(struct sockaddr_dl *sdl, socklen_t socklen, uint16_t ifindex,
    uint8_t type, const void *name, uint8_t namelen, const void *addr,
    uint8_t addrlen)
{
	socklen_t len;

	sdl->sdl_family = AF_LINK;
	sdl->sdl_slen = 0;
	len = sockaddr_dl_measure(namelen, addrlen);
	if (len > socklen) {
		sdl->sdl_len = socklen;
#ifdef DIAGNOSTIC
		printf("%s: too long: %u > %u\n", __func__, (u_int)len,
		    (u_int)socklen);
#endif
		return NULL;
	}
	sdl->sdl_len = len;
	sdl->sdl_index = ifindex;
	sdl->sdl_type = type;
	memset(&sdl->sdl_data[0], 0, namelen + addrlen);
	if (name != NULL) {
		memcpy(&sdl->sdl_data[0], name, namelen);
		sdl->sdl_nlen = namelen;
	} else
		sdl->sdl_nlen = 0;
	if (addr != NULL) {
		memcpy(&sdl->sdl_data[sdl->sdl_nlen], addr, addrlen);
		sdl->sdl_alen = addrlen;
	} else
		sdl->sdl_alen = 0;
	return sdl;
}

static int
sockaddr_dl_cmp(const struct sockaddr *sa1, const struct sockaddr *sa2)
{
	int rc;
	const uint_fast8_t indexofs = offsetof(struct sockaddr_dl, sdl_index);
	const uint_fast8_t nlenofs = offsetof(struct sockaddr_dl, sdl_nlen);
	uint_fast8_t dataofs = offsetof(struct sockaddr_dl, sdl_data[0]);
	const struct sockaddr_dl *sdl1, *sdl2;

	sdl1 = satocsdl(sa1);
	sdl2 = satocsdl(sa2);

	rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
	    indexofs, nlenofs);

	if (rc != 0)
		return rc;

	rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
	    dataofs, dataofs + MIN(sdl1->sdl_nlen, sdl2->sdl_nlen));

	if (rc != 0)
		return rc;

	if (sdl1->sdl_nlen != sdl2->sdl_nlen)
		return sdl1->sdl_nlen - sdl2->sdl_nlen;

	dataofs += sdl1->sdl_nlen;

	rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
	    dataofs, dataofs + MIN(sdl1->sdl_alen, sdl2->sdl_alen));

	if (rc != 0)
		return rc;

	if (sdl1->sdl_alen != sdl2->sdl_alen)
		return sdl1->sdl_alen - sdl2->sdl_alen;

	dataofs += sdl1->sdl_alen;

	rc = submemcmp(sdl1, sdl2, sdl1->sdl_len, sdl2->sdl_len,
	    dataofs, dataofs + MIN(sdl1->sdl_slen, sdl2->sdl_slen));

	if (sdl1->sdl_slen != sdl2->sdl_slen)
		return sdl1->sdl_slen - sdl2->sdl_slen;

	return sdl1->sdl_len - sdl2->sdl_len;
}

struct sockaddr_dl *
sockaddr_dl_setaddr(struct sockaddr_dl *sdl, socklen_t socklen,
    const void *addr, uint8_t addrlen)
{
	socklen_t len;

	len = sockaddr_dl_measure(sdl->sdl_nlen, addrlen);
	if (len > socklen) {
#ifdef DIAGNOSTIC
		printf("%s: too long: %u > %u\n", __func__, (u_int)len,
		    (u_int)socklen);
#endif
		return NULL;
	}
	memcpy(&sdl->sdl_data[sdl->sdl_nlen], addr, addrlen);
	sdl->sdl_alen = addrlen;
	sdl->sdl_len = len;
	return sdl;
}