/*      $NetBSD: if.c,v 1.29 2021/03/23 18:16:53 christos Exp $ */
/*      $KAME: if.c,v 1.36 2004/11/30 22:32:01 suz 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.
 */

#define RTM_NAMES
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <net/if_types.h>
#include <ifaddrs.h>
#ifdef __FreeBSD__
#include <net/ethernet.h>
#else
#include <net/if_ether.h>
#endif
#include <net/route.h>
#include <net/if_dl.h>
#include <netinet/in.h>
#include <netinet/icmp6.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>

#include "rtadvd.h"
#include "if.h"
#include "logit.h"
#include "prog_ops.h"

#ifndef RT_ROUNDUP
#define RT_ROUNDUP(a)                                                          \
        ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
#define RT_ADVANCE(x, n) (x += RT_ROUNDUP((n)->sa_len))
#endif

static void
get_rtaddrs(int addrs, const struct sockaddr *sa,
    const struct sockaddr **rti_info)
{
        int i;

        for (i = 0; i < RTAX_MAX; i++) {
                if (addrs & (1 << i)) {
                        rti_info[i] = sa;
                        RT_ADVANCE(sa, sa);
                }
                else
                        rti_info[i] = NULL;
        }
}

struct sockaddr_dl *
if_nametosdl(const char *name)
{
        struct ifaddrs *ifap, *ifa;
        struct sockaddr_dl *sdl;

        if (getifaddrs(&ifap) != 0)
                return (NULL);

        for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
                if (strcmp(ifa->ifa_name, name) != 0)
                        continue;
                if (ifa->ifa_addr->sa_family != AF_LINK)
                        continue;

                sdl = malloc(ifa->ifa_addr->sa_len);
                if (!sdl)
                        continue;       /*XXX*/

                memcpy(sdl, ifa->ifa_addr, ifa->ifa_addr->sa_len);
                freeifaddrs(ifap);
                return (sdl);
        }

        freeifaddrs(ifap);
        return (NULL);
}

int
if_getmtu(const char *name)
{
        struct ifreq ifr;
        int s, mtu;

        if ((s = prog_socket(AF_INET6, SOCK_DGRAM, 0)) < 0)
                return 0;

        memset(&ifr, 0, sizeof(ifr));
        ifr.ifr_addr.sa_family = AF_INET6;
        strncpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
        if (prog_ioctl(s, SIOCGIFMTU, &ifr) != -1)
                mtu = ifr.ifr_mtu;
        else
                mtu = 0;
        prog_close(s);

        return mtu;
}

/* give interface index and its old flags, then new flags returned */
int
if_getflags(unsigned int ifindex, int oifflags)
{
        struct ifreq ifr;
        int s;

        if ((s = prog_socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
                logit(LOG_ERR, "%s: socket: %m", __func__);
                return (oifflags & ~IFF_UP);
        }

        memset(&ifr, 0, sizeof(ifr));
        if_indextoname(ifindex, ifr.ifr_name);
        if (prog_ioctl(s, SIOCGIFFLAGS, &ifr) < 0) {
                logit(LOG_ERR, "%s: ioctl:SIOCGIFFLAGS: failed for %s",
                       __func__, ifr.ifr_name);
                prog_close(s);
                return (oifflags & ~IFF_UP);
        }
        prog_close(s);
        return (ifr.ifr_flags);
}

#define ROUNDUP8(a) (1 + (((a) - 1) | 7))
int
lladdropt_length(struct sockaddr_dl *sdl)
{
        switch (sdl->sdl_type) {
        case IFT_ETHER:
        case IFT_FDDI:
                return(ROUNDUP8(ETHER_ADDR_LEN + 2));
        default:
                return(0);
        }
}

void
lladdropt_fill(struct sockaddr_dl *sdl, struct nd_opt_hdr *ndopt)
{
        char *addr;

        ndopt->nd_opt_type = ND_OPT_SOURCE_LINKADDR; /* fixed */

        switch (sdl->sdl_type) {
        case IFT_ETHER:
        case IFT_FDDI:
                ndopt->nd_opt_len = (ROUNDUP8(ETHER_ADDR_LEN + 2)) >> 3;
                addr = (char *)(ndopt + 1);
                memcpy(addr, LLADDR(sdl), ETHER_ADDR_LEN);
                break;
        default:
                logit(LOG_ERR, "%s: unsupported link type(%d)",
                    __func__, sdl->sdl_type);
                exit(1);
        }

        return;
}

#define FILTER_MATCH(type, filter) ((0x1 << type) & filter)
#define SIN6(s) ((const struct sockaddr_in6 *)(s))
#define SDL(s) ((const struct sockaddr_dl *)(s))
char *
get_next_msg(char *buf, char *lim, unsigned int ifindex, size_t *lenp,
    int filter)
{
        struct rt_msghdr *rtm;
        struct ifa_msghdr *ifam;
        const struct sockaddr *sa, *dst, *gw, *ifa, *rti_info[RTAX_MAX];

        *lenp = 0;
        for (rtm = (struct rt_msghdr *)buf;
             rtm < (struct rt_msghdr *)lim;
             rtm = (struct rt_msghdr *)(((char *)rtm) + rtm->rtm_msglen)) {
                /* just for safety */
                if (!rtm->rtm_msglen) {
                        logit(LOG_WARNING, "%s: rtm_msglen is 0 "
                                "(buf=%p lim=%p rtm=%p)", __func__,
                                buf, lim, rtm);
                        break;
                }
                if (FILTER_MATCH(rtm->rtm_type, filter) == 0) {
                        continue;
                }

                switch (rtm->rtm_type) {
                case RTM_GET:
                case RTM_ADD:
                case RTM_DELETE:
                        /* address related checks */
                        sa = (struct sockaddr *)(rtm + 1);
                        get_rtaddrs(rtm->rtm_addrs, sa, rti_info);
                        if ((dst = rti_info[RTAX_DST]) == NULL ||
                            dst->sa_family != AF_INET6)
                                continue;

                        if (IN6_IS_ADDR_LINKLOCAL(&SIN6(dst)->sin6_addr) ||
                            IN6_IS_ADDR_MULTICAST(&SIN6(dst)->sin6_addr))
                                continue;

                        if ((gw = rti_info[RTAX_GATEWAY]) == NULL ||
                            gw->sa_family != AF_LINK)
                                continue;
                        if (ifindex && SDL(gw)->sdl_index != ifindex)
                                continue;

                        if (rti_info[RTAX_NETMASK] == NULL)
                                continue;

                        /* found */
                        *lenp = rtm->rtm_msglen;
                        return (char *)rtm;
                        /* NOTREACHED */
                case RTM_NEWADDR:
                case RTM_DELADDR:
                        ifam = (struct ifa_msghdr *)rtm;

                        /* address related checks */
                        sa = (struct sockaddr *)(ifam + 1);
                        get_rtaddrs(ifam->ifam_addrs, sa, rti_info);
                        if ((ifa = rti_info[RTAX_IFA]) == NULL ||
                            (ifa->sa_family != AF_INET &&
                             ifa->sa_family != AF_INET6))
                                continue;

                        if (ifa->sa_family == AF_INET6 &&
                            (IN6_IS_ADDR_LINKLOCAL(&SIN6(ifa)->sin6_addr) ||
                             IN6_IS_ADDR_MULTICAST(&SIN6(ifa)->sin6_addr)))
                                continue;

                        if (ifindex && ifam->ifam_index != ifindex)
                                continue;

                        /* found */
                        *lenp = ifam->ifam_msglen;
                        return (char *)rtm;
                        /* NOTREACHED */
#ifdef RTM_IFANNOUNCE
                case RTM_IFANNOUNCE:
#endif
                case RTM_IFINFO:
                        /* found */
                        *lenp = rtm->rtm_msglen;
                        return (char *)rtm;
                        /* NOTREACHED */
                }
        }

        return (char *)rtm;
}
#undef FILTER_MATCH

const struct in6_addr *
get_addr(const void *buf)
{
        const struct rt_msghdr *rtm = buf;
        const struct sockaddr *sa, *rti_info[RTAX_MAX];

        sa = (const struct sockaddr *)(rtm + 1);
        get_rtaddrs(rtm->rtm_addrs, sa, rti_info);

        return &SIN6(rti_info[RTAX_DST])->sin6_addr;
}

unsigned int
get_rtm_ifindex(const void *buf)
{
        const struct rt_msghdr *rtm = buf;
        const struct sockaddr *sa, *rti_info[RTAX_MAX];

        sa = (const struct sockaddr *)(rtm + 1);
        get_rtaddrs(rtm->rtm_addrs, sa, rti_info);

        return SDL(rti_info[RTAX_GATEWAY])->sdl_index;
}

unsigned int
get_ifm_ifindex(const void *buf)
{
        const struct if_msghdr *ifm = buf;

        return ifm->ifm_index;
}

unsigned int
get_ifam_ifindex(const void *buf)
{
        const struct ifa_msghdr *ifam = buf;

        return ifam->ifam_index;
}

int
get_ifm_flags(const void *buf)
{
        const struct if_msghdr *ifm = buf;

        return ifm->ifm_flags;
}

#ifdef RTM_IFANNOUNCE
unsigned int
get_ifan_ifindex(const void *buf)
{
        const struct if_announcemsghdr *ifan = buf;

        return ifan->ifan_index;
}

int
get_ifan_what(const void *buf)
{
        const struct if_announcemsghdr *ifan = buf;

        return (int)ifan->ifan_what;
}
#endif

int
get_prefixlen(const void *buf)
{
        const struct rt_msghdr *rtm = buf;
        const struct sockaddr *sa, *rti_info[RTAX_MAX];
        const unsigned char *p, *lim;

        sa = (const struct sockaddr *)(rtm + 1);
        get_rtaddrs(rtm->rtm_addrs, sa, rti_info);
        sa = rti_info[RTAX_NETMASK];

        p = (const unsigned char *)(&SIN6(sa)->sin6_addr);
        lim = (const unsigned char *)sa + sa->sa_len;
        return prefixlen(p, lim);
}

int
prefixlen(const unsigned char *p, const unsigned char *lim)
{
        int masklen;

        for (masklen = 0; p < lim; p++) {
                switch (*p) {
                case 0xff:
                        masklen += 8;
                        break;
                case 0xfe:
                        masklen += 7;
                        break;
                case 0xfc:
                        masklen += 6;
                        break;
                case 0xf8:
                        masklen += 5;
                        break;
                case 0xf0:
                        masklen += 4;
                        break;
                case 0xe0:
                        masklen += 3;
                        break;
                case 0xc0:
                        masklen += 2;
                        break;
                case 0x80:
                        masklen += 1;
                        break;
                case 0x00:
                        break;
                default:
                        return -1;
                }
        }

        return masklen;
}

int
rtmsg_type(const void *buf)
{
        const struct rt_msghdr *rtm = buf;

        return rtm->rtm_type;
}

const char *
rtmsg_typestr(const void *buf)
{
        const struct rt_msghdr *rtm = buf;

        return rtm->rtm_type < __arraycount(rtm_names)
            ? rtm_names[rtm->rtm_type] : "*unknown*";
}

int
rtmsg_len(const void *buf)
{
        const struct rt_msghdr *rtm = buf;

        return rtm->rtm_msglen;
}