/*      $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 */
       }
}

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