/*      $NetBSD: rthdr.c,v 1.19 2019/05/29 02:30:42 msaitoh Exp $       */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 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>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: rthdr.c,v 1.19 2019/05/29 02:30:42 msaitoh Exp $");
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <netinet/in.h>
#include <netinet/ip6.h>

#include <assert.h>
#include <string.h>
#include <stdio.h>

#ifdef __weak_alias
__weak_alias(inet6_rthdr_add,_inet6_rthdr_add)
__weak_alias(inet6_rthdr_getaddr,_inet6_rthdr_getaddr)
__weak_alias(inet6_rthdr_getflags,_inet6_rthdr_getflags)
__weak_alias(inet6_rthdr_init,_inet6_rthdr_init)
__weak_alias(inet6_rthdr_lasthop,_inet6_rthdr_lasthop)
__weak_alias(inet6_rthdr_segments,_inet6_rthdr_segments)
__weak_alias(inet6_rthdr_space,_inet6_rthdr_space)
__weak_alias(inet6_rth_space, _inet6_rth_space)
__weak_alias(inet6_rth_init, _inet6_rth_init)
__weak_alias(inet6_rth_add, _inet6_rth_add)
__weak_alias(inet6_rth_reverse, _inet6_rth_reverse)
__weak_alias(inet6_rth_segments, _inet6_rth_segments)
__weak_alias(inet6_rth_getaddr, _inet6_rth_getaddr)
#endif

/*
 * RFC2292 API
 */

size_t
inet6_rthdr_space(int type, int seg)
{
        switch (type) {
        case IPV6_RTHDR_TYPE_0:
                if (seg < 1 || seg > 23)
                        return (0);
                return (CMSG_SPACE(sizeof(struct in6_addr) * seg +
                    sizeof(struct ip6_rthdr0)));
        default:
                return (0);
        }
}

struct cmsghdr *
inet6_rthdr_init(void *bp, int type)
{
        struct cmsghdr *ch;
        struct ip6_rthdr *rthdr;

        _DIAGASSERT(bp != NULL);

        ch = (struct cmsghdr *)bp;
        rthdr = (struct ip6_rthdr *)(void *)CMSG_DATA(ch);

        ch->cmsg_level = IPPROTO_IPV6;
        ch->cmsg_type = IPV6_RTHDR;

        switch (type) {
        case IPV6_RTHDR_TYPE_0:
#ifdef COMPAT_RFC2292
                ch->cmsg_len = CMSG_LEN(sizeof(struct ip6_rthdr0) -
                    sizeof(struct in6_addr));
#else
                ch->cmsg_len = CMSG_LEN(sizeof(struct ip6_rthdr0));
#endif
                (void)memset(rthdr, 0, sizeof(struct ip6_rthdr0));
                rthdr->ip6r_type = IPV6_RTHDR_TYPE_0;
                return (ch);
        default:
                return (NULL);
        }
}

int
inet6_rthdr_add(struct cmsghdr *cmsg, const struct in6_addr *addr, u_int flags)
{
        struct ip6_rthdr *rthdr;

        _DIAGASSERT(cmsg != NULL);
        _DIAGASSERT(addr != NULL);

        rthdr = (struct ip6_rthdr *)(void *)CMSG_DATA(cmsg);

        switch (rthdr->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
        {
                size_t len;
                struct ip6_rthdr0 *rt0 = (struct ip6_rthdr0 *)(void *)rthdr;
                if (flags != IPV6_RTHDR_LOOSE && flags != IPV6_RTHDR_STRICT)
                        return (-1);
                if (rt0->ip6r0_segleft == 23)
                        return (-1);
                if (flags != IPV6_RTHDR_LOOSE)
                        return (-1);
                rt0->ip6r0_segleft++;
                (void)memcpy(((caddr_t)(void *)rt0) +
                    ((rt0->ip6r0_len + 1) << 3), addr, sizeof(struct in6_addr));
                rt0->ip6r0_len += sizeof(struct in6_addr) >> 3;
                len = CMSG_LEN((rt0->ip6r0_len + 1) << 3);
                _DIAGASSERT(__type_fit(socklen_t, len));
                cmsg->cmsg_len = (socklen_t)len;
                break;
        }
        default:
                return (-1);
        }

        return (0);
}

int
inet6_rthdr_lasthop(struct cmsghdr *cmsg, unsigned int flags)
{
        struct ip6_rthdr *rthdr;

        _DIAGASSERT(cmsg != NULL);

        rthdr = (struct ip6_rthdr *)(void *)CMSG_DATA(cmsg);

        switch (rthdr->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
        {
                struct ip6_rthdr0 *rt0 = (struct ip6_rthdr0 *)(void *)rthdr;
                if (rt0->ip6r0_segleft > 23)
                        return (-1);
                if (flags != IPV6_RTHDR_LOOSE)
                        return (-1);
                break;
        }
        default:
                return (-1);
        }

        return (0);
}

#if 0
int
inet6_rthdr_reverse(const struct cmsghdr *in, struct cmsghdr *out)
{

        return (-1);
}
#endif

int
inet6_rthdr_segments(const struct cmsghdr *cmsg)
{
        const struct ip6_rthdr *rthdr;

        _DIAGASSERT(cmsg != NULL);

        rthdr = __UNCONST(CCMSG_DATA(cmsg));

        switch (rthdr->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
        {
                const struct ip6_rthdr0 *rt0 =
                    (const struct ip6_rthdr0 *)(const void *)rthdr;
                size_t len;

                if (rt0->ip6r0_len % 2 || 46 < rt0->ip6r0_len)
                        return (-1);

                len = (rt0->ip6r0_len * 8) / sizeof(struct in6_addr);
                _DIAGASSERT(__type_fit(int, len));
                return (int)len;
        }

        default:
                return (-1);
        }
}

struct in6_addr *
inet6_rthdr_getaddr(struct cmsghdr *cmsg, int idx)
{
        struct ip6_rthdr *rthdr;

        _DIAGASSERT(cmsg != NULL);

        rthdr = (struct ip6_rthdr *)(void *)CMSG_DATA(cmsg);

        switch (rthdr->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
        {
                struct ip6_rthdr0 *rt0 = (struct ip6_rthdr0 *)(void *)rthdr;
                int naddr;
                size_t len;

                if (rt0->ip6r0_len % 2 || 46 < rt0->ip6r0_len)
                        return NULL;
                len = (rt0->ip6r0_len * 8) / sizeof(struct in6_addr);
                _DIAGASSERT(__type_fit(int, len));
                naddr = (int)len;
                if (idx <= 0 || naddr < idx)
                        return NULL;
#ifdef COMPAT_RFC2292
                return ((struct in6_addr *)(void *)(rt0 + 1)) + idx - 1;
#else
                return ((struct in6_addr *)(void *)(rt0 + 1)) + idx;
#endif
        }

        default:
                return NULL;
        }
}

int
inet6_rthdr_getflags(const struct cmsghdr *cmsg, int idx)
{
        const struct ip6_rthdr *rthdr;

        _DIAGASSERT(cmsg != NULL);

        rthdr = __UNCONST(CCMSG_DATA(cmsg));

        switch (rthdr->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
        {
                const struct ip6_rthdr0 *rt0 = (const struct ip6_rthdr0 *)
                (const void *)rthdr;
                int naddr;
                size_t len;

                if (rt0->ip6r0_len % 2 || 46 < rt0->ip6r0_len)
                        return (-1);
                len = (rt0->ip6r0_len * 8) / sizeof(struct in6_addr);
                _DIAGASSERT(__type_fit(int, len));
                naddr = (int)len;
                if (idx < 0 || naddr < idx)
                        return (-1);
                return IPV6_RTHDR_LOOSE;
        }

        default:
                return (-1);
        }
}

/*
 * RFC3542 (2292bis) API
 */

socklen_t
inet6_rth_space(int type, int segments)
{
        switch (type) {
        case IPV6_RTHDR_TYPE_0:
                return (((segments * 2) + 1) << 3);
        default:
                return (0);     /* type not supported */
        }
}

void *
inet6_rth_init(void *bp, socklen_t bp_len, int type, int segments)
{
        struct ip6_rthdr *rth;
        struct ip6_rthdr0 *rth0;

        _DIAGASSERT(bp != NULL);

        rth = (struct ip6_rthdr *)bp;

        switch (type) {
        case IPV6_RTHDR_TYPE_0:
                /* length validation */
                if (bp_len < inet6_rth_space(IPV6_RTHDR_TYPE_0, segments))
                        return (NULL);

                memset(bp, 0, bp_len);
                rth0 = (struct ip6_rthdr0 *)(void *)rth;
                rth0->ip6r0_len = segments * 2;
                rth0->ip6r0_type = IPV6_RTHDR_TYPE_0;
                rth0->ip6r0_segleft = 0;
                rth0->ip6r0_reserved = 0;
                break;
        default:
                return (NULL);  /* type not supported */
        }

        return (bp);
}

int
inet6_rth_add(void *bp, const struct in6_addr *addr)
{
        struct ip6_rthdr *rth;
        struct ip6_rthdr0 *rth0;
        struct in6_addr *nextaddr;

        _DIAGASSERT(bp != NULL);

        rth = (struct ip6_rthdr *)bp;

        switch (rth->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
                rth0 = (struct ip6_rthdr0 *)(void *)rth;
                nextaddr = (struct in6_addr *)(void *)(rth0 + 1)
                    + rth0->ip6r0_segleft;
                *nextaddr = *addr;
                rth0->ip6r0_segleft++;
                break;
        default:
                return (-1);    /* type not supported */
        }

        return (0);
}

int
inet6_rth_reverse(const void *in, void *out)
{
        const struct ip6_rthdr *rth_in;
        const struct ip6_rthdr0 *rth0_in;
        struct ip6_rthdr0 *rth0_out;
        int i, segments;

        _DIAGASSERT(in != NULL);
        _DIAGASSERT(out != NULL);

        rth_in = (const struct ip6_rthdr *)in;

        switch (rth_in->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
                rth0_in = (const struct ip6_rthdr0 *)in;
                rth0_out = (struct ip6_rthdr0 *)out;

                /* parameter validation XXX too paranoid? */
                if (rth0_in->ip6r0_len % 2)
                        return (-1);
                segments = rth0_in->ip6r0_len / 2;

                /* we can't use memcpy here, since in and out may overlap */
                memmove((void *)rth0_out, (const void *)rth0_in,
                        (unsigned int)(((rth0_in->ip6r0_len) + 1) << 3));
                rth0_out->ip6r0_segleft = segments;

                /* reverse the addresses */
                for (i = 0; i < segments / 2; i++) {
                        struct in6_addr addr_tmp, *addr1, *addr2;

                        addr1 = (struct in6_addr *)(void *)(rth0_out + 1) + i;
                        addr2 = (struct in6_addr *)(void *)(rth0_out + 1) +
                                (segments - i - 1);
                        addr_tmp = *addr1;
                        *addr1 = *addr2;
                        *addr2 = addr_tmp;
                }
                
                break;
        default:
                return (-1);    /* type not supported */
        }

        return (0);
}

int
inet6_rth_segments(const void *bp)
{
        const struct ip6_rthdr *rh;
        const struct ip6_rthdr0 *rh0;
        unsigned int addrs;

        _DIAGASSERT(bp != NULL);

        rh = (const struct ip6_rthdr *)bp;

        switch (rh->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
                rh0 = (const struct ip6_rthdr0 *)bp;

                /*
                 * Validation for a type-0 routing header.
                 * Is this too strict?
                 */
                if ((rh0->ip6r0_len % 2) != 0 ||
                    (addrs = (rh0->ip6r0_len / 2)) < rh0->ip6r0_segleft)
                        return (-1);

                return (addrs);
        default:
                return (-1);    /* unknown type */
        }
}

struct in6_addr *
inet6_rth_getaddr(const void *bp, int idx)
{
        const struct ip6_rthdr *rh;
        const struct ip6_rthdr0 *rh0;
        unsigned int addrs;

        _DIAGASSERT(bp != NULL);

        rh = (const struct ip6_rthdr *)bp;

        switch (rh->ip6r_type) {
        case IPV6_RTHDR_TYPE_0:
                 rh0 = (const struct ip6_rthdr0 *)bp;
                 
                /*
                 * Validation for a type-0 routing header.
                 * Is this too strict?
                 */
                if ((rh0->ip6r0_len % 2) != 0 ||
                    (addrs = (rh0->ip6r0_len / 2)) < rh0->ip6r0_segleft)
                        return (NULL);

                if (idx < 0 || addrs <= (unsigned int)idx)
                        return (NULL);

                return (((struct in6_addr *)(void *)__UNCONST(rh0 + 1)) + idx);
        default:
                return (NULL);  /* unknown type */
        }
}