/*	$NetBSD: scope6.c,v 1.23 2020/06/16 17:12:18 maxv Exp $	*/
/*	$KAME$	*/

/*
 * Copyright (C) 2000 WIDE Project.
 * 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 project 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 PROJECT 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 PROJECT 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: scope6.c,v 1.23 2020/06/16 17:12:18 maxv Exp $");

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/systm.h>
#include <sys/queue.h>
#include <sys/syslog.h>

#include <net/if.h>

#include <netinet/in.h>

#include <netinet6/in6_var.h>
#include <netinet6/scope6_var.h>

#ifdef ENABLE_DEFAULT_SCOPE
int ip6_use_defzone = 1;
#else
int ip6_use_defzone = 0;
#endif

static struct scope6_id sid_default;
#define SID(ifp) \
    ((ifp)->if_afdata[AF_INET6] == NULL ? NULL : \
	((struct in6_ifextra *)(ifp)->if_afdata[AF_INET6])->scope6_id)

void
scope6_init(void)
{

	memset(&sid_default, 0, sizeof(sid_default));
}

struct scope6_id *
scope6_ifattach(struct ifnet *ifp)
{
	struct scope6_id *sid;

	sid = malloc(sizeof(*sid), M_IFADDR, M_WAITOK | M_ZERO);

	/*
	 * XXX: IPV6_ADDR_SCOPE_xxx macros are not standard.
	 * Should we rather hardcode here?
	 */
	sid->s6id_list[IPV6_ADDR_SCOPE_INTFACELOCAL] = ifp->if_index;
	sid->s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL] = ifp->if_index;
#ifdef MULTI_SCOPE
	/* by default, we don't care about scope boundary for these scopes. */
	sid->s6id_list[IPV6_ADDR_SCOPE_SITELOCAL] = 1;
	sid->s6id_list[IPV6_ADDR_SCOPE_ORGLOCAL] = 1;
#endif

	return sid;
}

void
scope6_ifdetach(struct scope6_id *sid)
{

	free(sid, M_IFADDR);
}

/*
 * Get a scope of the address. Interface-local, link-local, site-local
 * or global.
 */
int
in6_addrscope(const struct in6_addr *addr)
{
	int scope;

	if (addr->s6_addr[0] == 0xfe) {
		scope = addr->s6_addr[1] & 0xc0;

		switch (scope) {
		case 0x80:
			return IPV6_ADDR_SCOPE_LINKLOCAL;
		case 0xc0:
			return IPV6_ADDR_SCOPE_SITELOCAL;
		default:
			return IPV6_ADDR_SCOPE_GLOBAL; /* just in case */
		}
	}

	if (addr->s6_addr[0] == 0xff) {
		scope = addr->s6_addr[1] & 0x0f;

		/*
		 * due to other scope such as reserved,
		 * return scope doesn't work.
		 */
		switch (scope) {
		case IPV6_ADDR_SCOPE_INTFACELOCAL:
			return IPV6_ADDR_SCOPE_INTFACELOCAL;
		case IPV6_ADDR_SCOPE_LINKLOCAL:
			return IPV6_ADDR_SCOPE_LINKLOCAL;
		case IPV6_ADDR_SCOPE_SITELOCAL:
			return IPV6_ADDR_SCOPE_SITELOCAL;
		default:
			return IPV6_ADDR_SCOPE_GLOBAL;
		}
	}

	if (memcmp(&in6addr_loopback, addr, sizeof(*addr) - 1) == 0) {
		if (addr->s6_addr[15] == 1) /* loopback */
			return IPV6_ADDR_SCOPE_LINKLOCAL;
		if (addr->s6_addr[15] == 0) {
			/*
			 * Regard the unspecified addresses as global,
			 * since it has no ambiguity.
			 * XXX: not sure if it's correct...
			 */
			return IPV6_ADDR_SCOPE_GLOBAL;
		}
	}

	return IPV6_ADDR_SCOPE_GLOBAL;
}

uint32_t
scope6_addr2default(const struct in6_addr *addr)
{
	uint32_t id;

	/*
	 * special case: The loopback address should be considered as
	 * link-local, but there's no ambiguity in the syntax.
	 */
	if (IN6_IS_ADDR_LOOPBACK(addr))
		return 0;

	/*
	 * XXX: 32-bit read is atomic on all our platforms, is it OK
	 * not to lock here?
	 */
	id = sid_default.s6id_list[in6_addrscope(addr)];

	return id;
}

/*
 * Validate the specified scope zone ID in the sin6_scope_id field.  If the ID
 * is unspecified (=0), needs to be specified, and the default zone ID can be
 * used, the default value will be used.
 * This routine then generates the kernel-internal form: if the address scope
 * of is interface-local or link-local, embed the interface index in the
 * address.
 */
int
sa6_embedscope(struct sockaddr_in6 *sin6, int defaultok)
{
	struct ifnet *ifp;
	uint32_t zoneid;

	if ((zoneid = sin6->sin6_scope_id) == 0 && defaultok)
		zoneid = scope6_addr2default(&sin6->sin6_addr);

	if (zoneid != 0 &&
	    (IN6_IS_SCOPE_LINKLOCAL(&sin6->sin6_addr) ||
	    IN6_IS_ADDR_MC_INTFACELOCAL(&sin6->sin6_addr))) {
		int s;
		/*
		 * At this moment, we only check interface-local and
		 * link-local scope IDs, and use interface indices as the
		 * zone IDs assuming a one-to-one mapping between interfaces
		 * and links.
		 */
		s = pserialize_read_enter();
		ifp = if_byindex(zoneid);
		if (ifp == NULL) {
			pserialize_read_exit(s);
			return ENXIO;
		}
		pserialize_read_exit(s);

		/* XXX assignment to 16bit from 32bit variable */
		sin6->sin6_addr.s6_addr16[1] = htons(zoneid & 0xffff);

		sin6->sin6_scope_id = 0;
	}

	return 0;
}

struct sockaddr *
sockaddr_in6_externalize(struct sockaddr *dst, socklen_t socklen,
    const struct sockaddr *src)
{
	struct sockaddr_in6 *sin6;

	sin6 = satosin6(sockaddr_copy(dst, socklen, src));

	if (sin6 == NULL || sa6_recoverscope(sin6) != 0)
		return NULL;

	return dst;
}

/*
 * generate standard sockaddr_in6 from embedded form.
 */
int
sa6_recoverscope(struct sockaddr_in6 *sin6)
{
	uint32_t zoneid;
	char ip6buf[INET6_ADDRSTRLEN];

	if (sin6->sin6_scope_id != 0) {
		log(LOG_NOTICE,
		    "%s: assumption failure (non 0 ID): %s%%%d\n", __func__,
		    IN6_PRINT(ip6buf, &sin6->sin6_addr), sin6->sin6_scope_id);
		/* XXX: proceed anyway... */
	}
	if (IN6_IS_SCOPE_LINKLOCAL(&sin6->sin6_addr) ||
	    IN6_IS_ADDR_MC_INTFACELOCAL(&sin6->sin6_addr)) {
		/*
		 * KAME assumption: link id == interface id
		 */
		zoneid = ntohs(sin6->sin6_addr.s6_addr16[1]);
		if (zoneid) {
			int s = pserialize_read_enter();
			if (!if_byindex(zoneid)) {
				pserialize_read_exit(s);
				return ENXIO;
			}
			pserialize_read_exit(s);
			sin6->sin6_addr.s6_addr16[1] = 0;
			sin6->sin6_scope_id = zoneid;
		}
	}

	return 0;
}

int
in6_setzoneid(struct in6_addr *in6, uint32_t zoneid)
{
	if (IN6_IS_SCOPE_EMBEDDABLE(in6))
		in6->s6_addr16[1] = htons(zoneid & 0xffff); /* XXX */

	return 0;
}

/*
 * Determine the appropriate scope zone ID for in6 and ifp.  If ret_id is
 * non NULL, it is set to the zone ID.  If the zone ID needs to be embedded
 * in the in6_addr structure, in6 will be modified.
 */
int
in6_setscope(struct in6_addr *in6, const struct ifnet *ifp, uint32_t *ret_id)
{
	int scope;
	uint32_t zoneid = 0;
	const struct scope6_id *sid = SID(ifp);

	if (sid == NULL) {
		log(LOG_NOTICE, "%s: no scope id for %s\n", __func__,
		    if_name(ifp));
		return EINVAL;
	}

	/*
	 * special case: the loopback address can only belong to a loopback
	 * interface.
	 */
	if (IN6_IS_ADDR_LOOPBACK(in6)) {
		if (!(ifp->if_flags & IFF_LOOPBACK)) {
			char ip6buf[INET6_ADDRSTRLEN];
			log(LOG_NOTICE, "%s: can't set scope for not loopback "
			    "interface %s and loopback address %s\n",
			    __func__, if_name(ifp), IN6_PRINT(ip6buf, in6));
			return EINVAL;
		} else {
			if (ret_id != NULL)
				*ret_id = 0; /* there's no ambiguity */
			return 0;
		}
	}

	scope = in6_addrscope(in6);

	switch (scope) {
	case IPV6_ADDR_SCOPE_INTFACELOCAL: /* should be interface index */
		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_INTFACELOCAL];
		break;

	case IPV6_ADDR_SCOPE_LINKLOCAL:
		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL];
		break;

	case IPV6_ADDR_SCOPE_SITELOCAL:
		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_SITELOCAL];
		break;

	case IPV6_ADDR_SCOPE_ORGLOCAL:
		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_ORGLOCAL];
		break;

	default:
		zoneid = 0;	/* XXX: treat as global. */
		break;
	}

	if (ret_id != NULL)
		*ret_id = zoneid;

	return in6_setzoneid(in6, zoneid);
}

const char *
in6_getscopename(const struct in6_addr *addr)
{
	switch (in6_addrscope(addr)) {
	case IPV6_ADDR_SCOPE_INTFACELOCAL:
		return "interface";
#if IPV6_ADDR_SCOPE_INTFACELOCAL != IPV6_ADDR_SCOPE_NODELOCAL
	case IPV6_ADDR_SCOPE_NODELOCAL:
		return "node";
#endif
	case IPV6_ADDR_SCOPE_LINKLOCAL:
		return "link";
	case IPV6_ADDR_SCOPE_SITELOCAL:
		return "site";
	case IPV6_ADDR_SCOPE_ORGLOCAL:
		return "organization";
	case IPV6_ADDR_SCOPE_GLOBAL:
		return "global";
	default:
		return "unknown";
	}
}

/*
 * Just clear the embedded scope identifier.  Return 0 if the original address
 * is intact; return non 0 if the address is modified.
 */
int
in6_clearscope(struct in6_addr *in6)
{
	int modified = 0;

	if (IN6_IS_SCOPE_LINKLOCAL(in6) || IN6_IS_ADDR_MC_INTFACELOCAL(in6)) {
		if (in6->s6_addr16[1] != 0)
			modified = 1;
		in6->s6_addr16[1] = 0;
	}

	return modified;
}