/*      $KAME: rtadvd.c,v 1.82 2003/08/05 12:34:23 itojun Exp $ */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * Copyright (C) 2011 Hiroki Sato <hrs@FreeBSD.org>
 * 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/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_types.h>
#include <net/if_media.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>

#include <arpa/inet.h>

#include <netinet/in_var.h>
#include <netinet6/nd6.h>

#include <time.h>
#include <unistd.h>
#include <stdio.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <libutil.h>
#include <netdb.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include <poll.h>

#include "pathnames.h"
#include "rtadvd.h"
#include "if.h"
#include "rrenum.h"
#include "advcap.h"
#include "timer_subr.h"
#include "timer.h"
#include "config.h"
#include "control.h"
#include "control_server.h"

#define RTADV_TYPE2BITMASK(type) (0x1 << type)

struct msghdr rcvmhdr;
static char *rcvcmsgbuf;
static size_t rcvcmsgbuflen;
static char *sndcmsgbuf = NULL;
static size_t sndcmsgbuflen;
struct msghdr sndmhdr;
struct iovec rcviov[2];
struct iovec sndiov[2];
struct sockaddr_in6 rcvfrom;
static const char *pidfilename = _PATH_RTADVDPID;
const char *conffile = _PATH_RTADVDCONF;
static struct pidfh *pfh;
static int dflag, sflag;
static int wait_shutdown;

#define PFD_RAWSOCK     0
#define PFD_RTSOCK      1
#define PFD_CSOCK       2
#define PFD_MAX         3

struct railist_head_t railist =
    TAILQ_HEAD_INITIALIZER(railist);
struct ifilist_head_t ifilist =
    TAILQ_HEAD_INITIALIZER(ifilist);

struct nd_optlist {
        TAILQ_ENTRY(nd_optlist) nol_next;
        struct nd_opt_hdr *nol_opt;
};
union nd_opt {
        struct nd_opt_hdr *opt_array[9];
        struct {
                struct nd_opt_hdr *zero;
                struct nd_opt_hdr *src_lladdr;
                struct nd_opt_hdr *tgt_lladdr;
                struct nd_opt_prefix_info *pi;
                struct nd_opt_rd_hdr *rh;
                struct nd_opt_mtu *mtu;
                TAILQ_HEAD(, nd_optlist) opt_list;
        } nd_opt_each;
};
#define opt_src_lladdr  nd_opt_each.src_lladdr
#define opt_tgt_lladdr  nd_opt_each.tgt_lladdr
#define opt_pi          nd_opt_each.pi
#define opt_rh          nd_opt_each.rh
#define opt_mtu         nd_opt_each.mtu
#define opt_list        nd_opt_each.opt_list

#define NDOPT_FLAG_SRCLINKADDR  (1 << 0)
#define NDOPT_FLAG_TGTLINKADDR  (1 << 1)
#define NDOPT_FLAG_PREFIXINFO   (1 << 2)
#define NDOPT_FLAG_RDHDR        (1 << 3)
#define NDOPT_FLAG_MTU          (1 << 4)
#define NDOPT_FLAG_RDNSS        (1 << 5)
#define NDOPT_FLAG_DNSSL        (1 << 6)
#define NDOPT_FLAG_PREF64       (1 << 7)

static uint32_t ndopt_flags[] = {
        [ND_OPT_SOURCE_LINKADDR]        = NDOPT_FLAG_SRCLINKADDR,
        [ND_OPT_TARGET_LINKADDR]        = NDOPT_FLAG_TGTLINKADDR,
        [ND_OPT_PREFIX_INFORMATION]     = NDOPT_FLAG_PREFIXINFO,
        [ND_OPT_REDIRECTED_HEADER]      = NDOPT_FLAG_RDHDR,
        [ND_OPT_MTU]                    = NDOPT_FLAG_MTU,
        [ND_OPT_RDNSS]                  = NDOPT_FLAG_RDNSS,
        [ND_OPT_DNSSL]                  = NDOPT_FLAG_DNSSL,
        [ND_OPT_PREF64]                 = NDOPT_FLAG_PREF64,
};

static void     rtadvd_shutdown(void);
static void     sock_open(struct sockinfo *);
static void     rtsock_open(struct sockinfo *);
static void     rtadvd_input(struct sockinfo *);
static void     rs_input(int, struct nd_router_solicit *,
                    struct in6_pktinfo *, struct sockaddr_in6 *);
static void     ra_input(int, struct nd_router_advert *,
                    struct in6_pktinfo *, struct sockaddr_in6 *);
static int      prefix_check(struct nd_opt_prefix_info *, struct rainfo *,
                    struct sockaddr_in6 *);
static int      nd6_options(struct nd_opt_hdr *, int,
                    union nd_opt *, uint32_t);
static void     free_ndopts(union nd_opt *);
static void     rtmsg_input(struct sockinfo *);
static void     set_short_delay(struct ifinfo *);
static int      check_accept_rtadv(int);

static void
usage(void)
{

        fprintf(stderr, "usage: rtadvd [-dDfRs] "
            "[-c configfile] [-C ctlsock] [-M ifname] [-p pidfile]\n");
        exit(1);
}

int
main(int argc, char *argv[])
{
        struct pollfd set[PFD_MAX];
        struct timespec *timeout;
        int i, ch;
        int fflag = 0, logopt;
        int error;
        pid_t pid, otherpid;

        /* get command line options and arguments */
        while ((ch = getopt(argc, argv, "c:C:dDfhM:p:Rs")) != -1) {
                switch (ch) {
                case 'c':
                        conffile = optarg;
                        break;
                case 'C':
                        ctrlsock.si_name = optarg;
                        break;
                case 'd':
                        dflag++;
                        break;
                case 'D':
                        dflag += 3;
                        break;
                case 'f':
                        fflag = 1;
                        break;
                case 'M':
                        mcastif = optarg;
                        break;
                case 'R':
                        fprintf(stderr, "rtadvd: "
                                "the -R option is currently ignored.\n");
                        /* accept_rr = 1; */
                        /* run anyway... */
                        break;
                case 's':
                        sflag = 1;
                        break;
                case 'p':
                        pidfilename = optarg;
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        logopt = LOG_NDELAY | LOG_PID;
        if (fflag)
                logopt |= LOG_PERROR;
        openlog("rtadvd", logopt, LOG_DAEMON);

        /* set log level */
        if (dflag > 2)
                (void)setlogmask(LOG_UPTO(LOG_DEBUG));
        else if (dflag > 1)
                (void)setlogmask(LOG_UPTO(LOG_INFO));
        else if (dflag > 0)
                (void)setlogmask(LOG_UPTO(LOG_NOTICE));
        else
                (void)setlogmask(LOG_UPTO(LOG_ERR));

        /* timer initialization */
        rtadvd_timer_init();

        pfh = pidfile_open(pidfilename, 0600, &otherpid);
        if (pfh == NULL) {
                if (errno == EEXIST)
                        errx(1, "%s already running, pid: %d",
                            getprogname(), otherpid);
                syslog(LOG_ERR,
                    "failed to open the pid file %s, run anyway.",
                    pidfilename);
        }
        if (!fflag)
                daemon(1, 0);

        sock_open(&sock);

        update_ifinfo(&ifilist, UPDATE_IFINFO_ALL);
        for (i = 0; i < argc; i++)
                update_persist_ifinfo(&ifilist, argv[i]);

        csock_open(&ctrlsock, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
        if (ctrlsock.si_fd == -1) {
                syslog(LOG_ERR, "cannot open control socket: %s",
                    strerror(errno));
                exit(1);
        }

        /* record the current PID */
        pid = getpid();
        pidfile_write(pfh);

        set[PFD_RAWSOCK].fd = sock.si_fd;
        set[PFD_RAWSOCK].events = POLLIN;
        if (sflag == 0) {
                rtsock_open(&rtsock);
                set[PFD_RTSOCK].fd = rtsock.si_fd;
                set[PFD_RTSOCK].events = POLLIN;
        } else
                set[PFD_RTSOCK].fd = -1;
        set[PFD_CSOCK].fd = ctrlsock.si_fd;
        set[PFD_CSOCK].events = POLLIN;
        signal(SIGTERM, set_do_shutdown);
        signal(SIGINT, set_do_shutdown);
        signal(SIGHUP, set_do_reload);

        error = csock_listen(&ctrlsock);
        if (error) {
                syslog(LOG_ERR, "cannot listen control socket: %s",
                    strerror(errno));
                exit(1);
        }

        /* load configuration file */
        set_do_reload(0);

        while (1) {
                if (is_do_shutdown())
                        rtadvd_shutdown();

                if (is_do_reload()) {
                        loadconfig_ifname(reload_ifname());
                        if (reload_ifname() == NULL)
                                syslog(LOG_INFO,
                                    "configuration file reloaded.");
                        else
                                syslog(LOG_INFO,
                                    "configuration file for %s reloaded.",
                                    reload_ifname());
                        reset_do_reload();
                }

                /* timeout handler update for active interfaces */
                rtadvd_update_timeout_handler();

                /* timer expiration check and reset the timer */
                timeout = rtadvd_check_timer();

                if (timeout != NULL) {
                        syslog(LOG_DEBUG,
                            "<%s> set timer to %ld:%ld. waiting for "
                            "inputs or timeout", __func__,
                            (long int)timeout->tv_sec,
                            (long int)timeout->tv_nsec / 1000);
                } else {
                        syslog(LOG_DEBUG,
                            "<%s> there's no timer. waiting for inputs",
                            __func__);
                }
                if ((i = poll(set, nitems(set),
                            timeout ? (timeout->tv_sec * 1000 +
                                timeout->tv_nsec / 1000 / 1000) : INFTIM)) < 0) {

                        /* EINTR would occur if a signal was delivered */
                        if (errno != EINTR)
                                syslog(LOG_ERR, "poll() failed: %s",
                                    strerror(errno));
                        continue;
                }
                if (i == 0)     /* timeout */
                        continue;
                if (rtsock.si_fd != -1 && set[PFD_RTSOCK].revents & POLLIN)
                        rtmsg_input(&rtsock);

                if (set[PFD_RAWSOCK].revents & POLLIN)
                        rtadvd_input(&sock);

                if (set[PFD_CSOCK].revents & POLLIN) {
                        int fd;

                        fd = csock_accept(&ctrlsock);
                        if (fd == -1)
                                syslog(LOG_ERR,
                                    "cannot accept() control socket: %s",
                                    strerror(errno));
                        else {
                                cm_handler_server(fd);
                                close(fd);
                        }
                }
        }
        exit(0);                /* NOTREACHED */
}

static void
rtadvd_shutdown(void)
{
        struct ifinfo *ifi;
        struct rainfo *rai;
        struct rdnss *rdn;
        struct dnssl *dns;

        if (wait_shutdown) {
                syslog(LOG_INFO,
                    "waiting expiration of the all RA timers.");

                TAILQ_FOREACH(ifi, &ifilist, ifi_next) {
                        /*
                         * Ignore !IFF_UP interfaces in waiting for shutdown.
                         */
                        if (!(ifi->ifi_flags & IFF_UP) &&
                            ifi->ifi_ra_timer != NULL) {
                                ifi->ifi_state = IFI_STATE_UNCONFIGURED;
                                rtadvd_remove_timer(ifi->ifi_ra_timer);
                                ifi->ifi_ra_timer = NULL;
                                syslog(LOG_DEBUG, "<%s> %s(idx=%d) is down. "
                                    "Timer removed and marked as UNCONFIGURED.",
                                     __func__, ifi->ifi_ifname,
                                    ifi->ifi_ifindex);
                        }
                }
                TAILQ_FOREACH(ifi, &ifilist, ifi_next) {
                        if (ifi->ifi_ra_timer != NULL)
                                break;
                }
                if (ifi == NULL) {
                        syslog(LOG_NOTICE, "gracefully terminated.");
                        exit(0);
                }

                sleep(1);
                return;
        }

        syslog(LOG_DEBUG, "<%s> cease to be an advertising router",
            __func__);

        wait_shutdown = 1;

        TAILQ_FOREACH(rai, &railist, rai_next) {
                rai->rai_lifetime = 0;
                TAILQ_FOREACH(rdn, &rai->rai_rdnss, rd_next)
                        rdn->rd_ltime = 0;
                TAILQ_FOREACH(dns, &rai->rai_dnssl, dn_next)
                        dns->dn_ltime = 0;
        }
        TAILQ_FOREACH(ifi, &ifilist, ifi_next) {
                if (!ifi->ifi_persist)
                        continue;
                if (ifi->ifi_state == IFI_STATE_UNCONFIGURED)
                        continue;
                if (ifi->ifi_ra_timer == NULL)
                        continue;
                if (ifi->ifi_ra_lastsent.tv_sec == 0 &&
                    ifi->ifi_ra_lastsent.tv_nsec == 0 &&
                    ifi->ifi_ra_timer != NULL) {
                        /*
                         * When RA configured but never sent,
                         * ignore the IF immediately.
                         */
                        rtadvd_remove_timer(ifi->ifi_ra_timer);
                        ifi->ifi_ra_timer = NULL;
                        ifi->ifi_state = IFI_STATE_UNCONFIGURED;
                        continue;
                }

                ifi->ifi_state = IFI_STATE_TRANSITIVE;

                /* Mark as the shut-down state. */
                ifi->ifi_rainfo_trans = ifi->ifi_rainfo;
                ifi->ifi_rainfo = NULL;

                ifi->ifi_burstcount = MAX_FINAL_RTR_ADVERTISEMENTS;
                ifi->ifi_burstinterval = MIN_DELAY_BETWEEN_RAS;

                ra_timer_update(ifi, &ifi->ifi_ra_timer->rat_tm);
                rtadvd_set_timer(&ifi->ifi_ra_timer->rat_tm,
                    ifi->ifi_ra_timer);
        }
        syslog(LOG_NOTICE, "final RA transmission started.");

        pidfile_remove(pfh);
        csock_close(&ctrlsock);
}

static void
rtmsg_input(struct sockinfo *s)
{
        int n, type, ifindex = 0, plen;
        size_t len;
        char msg[2048], *next, *lim;
        char ifname[IFNAMSIZ];
        struct if_announcemsghdr *ifan;
        struct rt_msghdr *rtm;
        struct prefix *pfx;
        struct rainfo *rai;
        struct in6_addr *addr;
        struct ifinfo *ifi;
        char addrbuf[INET6_ADDRSTRLEN];
        int prefixchange = 0;

        if (s == NULL) {
                syslog(LOG_ERR, "<%s> internal error", __func__);
                exit(1);
        }
        n = read(s->si_fd, msg, sizeof(msg));
        rtm = (struct rt_msghdr *)msg;
        syslog(LOG_DEBUG, "<%s> received a routing message "
            "(type = %d, len = %d)", __func__, rtm->rtm_type, n);

        if (n > rtm->rtm_msglen) {
                /*
                 * This usually won't happen for messages received on
                 * a routing socket.
                 */
                syslog(LOG_DEBUG,
                    "<%s> received data length is larger than "
                    "1st routing message len. multiple messages? "
                    "read %d bytes, but 1st msg len = %d",
                    __func__, n, rtm->rtm_msglen);
#if 0
                /* adjust length */
                n = rtm->rtm_msglen;
#endif
        }

        lim = msg + n;
        for (next = msg; next < lim; next += len) {
                int oldifflags;

                next = get_next_msg(next, lim, 0, &len,
                    RTADV_TYPE2BITMASK(RTM_ADD) |
                    RTADV_TYPE2BITMASK(RTM_DELETE) |
                    RTADV_TYPE2BITMASK(RTM_NEWADDR) |
                    RTADV_TYPE2BITMASK(RTM_DELADDR) |
                    RTADV_TYPE2BITMASK(RTM_IFINFO) |
                    RTADV_TYPE2BITMASK(RTM_IFANNOUNCE));
                if (len == 0)
                        break;
                type = ((struct rt_msghdr *)next)->rtm_type;
                switch (type) {
                case RTM_ADD:
                case RTM_DELETE:
                        ifindex = get_rtm_ifindex(next);
                        break;
                case RTM_NEWADDR:
                case RTM_DELADDR:
                        ifindex = (int)((struct ifa_msghdr *)next)->ifam_index;
                        break;
                case RTM_IFINFO:
                        ifindex = (int)((struct if_msghdr *)next)->ifm_index;
                        break;
                case RTM_IFANNOUNCE:
                        ifan = (struct if_announcemsghdr *)next;
                        switch (ifan->ifan_what) {
                        case IFAN_ARRIVAL:
                        case IFAN_DEPARTURE:
                                break;
                        default:
                                syslog(LOG_DEBUG,
                                    "<%s:%d> unknown ifan msg (ifan_what=%d)",
                                   __func__, __LINE__, ifan->ifan_what);
                                continue;
                        }

                        syslog(LOG_DEBUG, "<%s>: if_announcemsg (idx=%d:%d)",
                               __func__, ifan->ifan_index, ifan->ifan_what);
                        switch (ifan->ifan_what) {
                        case IFAN_ARRIVAL:
                                syslog(LOG_NOTICE,
                                    "interface added (idx=%d)",
                                    ifan->ifan_index);
                                update_ifinfo(&ifilist, ifan->ifan_index);
                                loadconfig_index(ifan->ifan_index);
                                break;
                        case IFAN_DEPARTURE:
                                syslog(LOG_NOTICE,
                                    "interface removed (idx=%d)",
                                    ifan->ifan_index);
                                rm_ifinfo_index(ifan->ifan_index);

                                /* Clear ifi_ifindex */
                                TAILQ_FOREACH(ifi, &ifilist, ifi_next) {
                                        if (ifi->ifi_ifindex
                                            == ifan->ifan_index) {
                                                ifi->ifi_ifindex = 0;
                                                break;
                                        }
                                }
                                update_ifinfo(&ifilist, ifan->ifan_index);
                                break;
                        }
                        continue;
                default:
                        /* should not reach here */
                        syslog(LOG_DEBUG,
                               "<%s:%d> unknown rtmsg %d on %s",
                               __func__, __LINE__, type,
                               if_indextoname(ifindex, ifname));
                        continue;
                }
                ifi = if_indextoifinfo(ifindex);
                if (ifi == NULL) {
                        syslog(LOG_DEBUG,
                            "<%s> ifinfo not found for idx=%d.  Why?",
                            __func__, ifindex);
                        continue;
                }
                rai = ifi->ifi_rainfo;
                if (rai == NULL) {
                        syslog(LOG_DEBUG,
                            "<%s> route changed on "
                            "non advertising interface(%s)",
                            __func__, ifi->ifi_ifname);
                        continue;
                }

                oldifflags = ifi->ifi_flags;
                /* init ifflags because it may have changed */
                update_ifinfo(&ifilist, ifindex);

                switch (type) {
                case RTM_ADD:
                        if (sflag)
                                break;  /* we aren't interested in prefixes  */

                        addr = get_addr(msg);
                        plen = get_prefixlen(msg);
                        /* sanity check for plen */
                        /* as RFC2373, prefixlen is at least 4 */
                        if (plen < 4 || plen > 127) {
                                syslog(LOG_INFO, "<%s> new interface route's"
                                    "plen %d is invalid for a prefix",
                                    __func__, plen);
                                break;
                        }
                        pfx = find_prefix(rai, addr, plen);
                        if (pfx) {
                                if (pfx->pfx_timer) {
                                        /*
                                         * If the prefix has been invalidated,
                                         * make it available again.
                                         */
                                        update_prefix(pfx);
                                        prefixchange = 1;
                                } else
                                        syslog(LOG_DEBUG,
                                            "<%s> new prefix(%s/%d) "
                                            "added on %s, "
                                            "but it was already in list",
                                            __func__,
                                            inet_ntop(AF_INET6, addr,
                                                (char *)addrbuf,
                                                sizeof(addrbuf)),
                                            plen, ifi->ifi_ifname);
                                break;
                        }
                        make_prefix(rai, ifindex, addr, plen);
                        prefixchange = 1;
                        break;
                case RTM_DELETE:
                        if (sflag)
                                break;

                        addr = get_addr(msg);
                        plen = get_prefixlen(msg);
                        /* sanity check for plen */
                        /* as RFC2373, prefixlen is at least 4 */
                        if (plen < 4 || plen > 127) {
                                syslog(LOG_INFO,
                                    "<%s> deleted interface route's "
                                    "plen %d is invalid for a prefix",
                                    __func__, plen);
                                break;
                        }
                        pfx = find_prefix(rai, addr, plen);
                        if (pfx == NULL) {
                                syslog(LOG_DEBUG,
                                    "<%s> prefix(%s/%d) was deleted on %s, "
                                    "but it was not in list",
                                    __func__, inet_ntop(AF_INET6, addr,
                                        (char *)addrbuf, sizeof(addrbuf)),
                                        plen, ifi->ifi_ifname);
                                break;
                        }
                        invalidate_prefix(pfx);
                        prefixchange = 1;
                        break;
                case RTM_NEWADDR:
                case RTM_DELADDR:
                case RTM_IFINFO:
                        break;
                default:
                        /* should not reach here */
                        syslog(LOG_DEBUG,
                            "<%s:%d> unknown rtmsg %d on %s",
                            __func__, __LINE__, type,
                            if_indextoname(ifindex, ifname));
                        return;
                }

                /* check if an interface flag is changed */
                if ((oldifflags & IFF_UP) && /* UP to DOWN */
                    !(ifi->ifi_flags & IFF_UP)) {
                        syslog(LOG_NOTICE,
                            "<interface %s becomes down. stop timer.",
                            ifi->ifi_ifname);
                        rtadvd_remove_timer(ifi->ifi_ra_timer);
                        ifi->ifi_ra_timer = NULL;
                } else if (!(oldifflags & IFF_UP) && /* DOWN to UP */
                    (ifi->ifi_flags & IFF_UP)) {
                        syslog(LOG_NOTICE,
                            "interface %s becomes up. restart timer.",
                            ifi->ifi_ifname);

                        ifi->ifi_state = IFI_STATE_TRANSITIVE;
                        ifi->ifi_burstcount =
                            MAX_INITIAL_RTR_ADVERTISEMENTS;
                        ifi->ifi_burstinterval =
                            MAX_INITIAL_RTR_ADVERT_INTERVAL;

                        ifi->ifi_ra_timer = rtadvd_add_timer(ra_timeout,
                            ra_timer_update, ifi, ifi);
                        ra_timer_update(ifi, &ifi->ifi_ra_timer->rat_tm);
                        rtadvd_set_timer(&ifi->ifi_ra_timer->rat_tm,
                            ifi->ifi_ra_timer);
                } else if (prefixchange &&
                    (ifi->ifi_flags & IFF_UP)) {
                        /*
                         * An advertised prefix has been added or invalidated.
                         * Will notice the change in a short delay.
                         */
                        set_short_delay(ifi);
                }
        }
}

void
rtadvd_input(struct sockinfo *s)
{
        ssize_t i;
        int *hlimp = NULL;
#ifdef OLDRAWSOCKET
        struct ip6_hdr *ip;
#endif
        struct icmp6_hdr *icp;
        int ifindex = 0;
        struct cmsghdr *cm;
        struct in6_pktinfo *pi = NULL;
        char ntopbuf[INET6_ADDRSTRLEN], ifnamebuf[IFNAMSIZ];
        struct in6_addr dst = in6addr_any;
        struct ifinfo *ifi;

        syslog(LOG_DEBUG, "<%s> enter", __func__);

        if (s == NULL) {
                syslog(LOG_ERR, "<%s> internal error", __func__);
                exit(1);
        }
        /*
         * Get message. We reset msg_controllen since the field could
         * be modified if we had received a message before setting
         * receive options.
         */
        rcvmhdr.msg_controllen = rcvcmsgbuflen;
        if ((i = recvmsg(s->si_fd, &rcvmhdr, 0)) < 0)
                return;

        /* extract optional information via Advanced API */
        for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&rcvmhdr);
             cm;
             cm = (struct cmsghdr *)CMSG_NXTHDR(&rcvmhdr, cm)) {
                if (cm->cmsg_level == IPPROTO_IPV6 &&
                    cm->cmsg_type == IPV6_PKTINFO &&
                    cm->cmsg_len == CMSG_LEN(sizeof(struct in6_pktinfo))) {
                        pi = (struct in6_pktinfo *)(CMSG_DATA(cm));
                        ifindex = pi->ipi6_ifindex;
                        dst = pi->ipi6_addr;
                }
                if (cm->cmsg_level == IPPROTO_IPV6 &&
                    cm->cmsg_type == IPV6_HOPLIMIT &&
                    cm->cmsg_len == CMSG_LEN(sizeof(int)))
                        hlimp = (int *)CMSG_DATA(cm);
        }
        if (ifindex == 0) {
                syslog(LOG_ERR, "failed to get receiving interface");
                return;
        }
        if (hlimp == NULL) {
                syslog(LOG_ERR, "failed to get receiving hop limit");
                return;
        }

        /*
         * If we happen to receive data on an interface which is now gone
         * or down, just discard the data.
         */
        ifi = if_indextoifinfo(pi->ipi6_ifindex);
        if (ifi == NULL || !(ifi->ifi_flags & IFF_UP)) {
                syslog(LOG_INFO,
                    "<%s> received data on a disabled interface (%s)",
                    __func__,
                    (ifi == NULL) ? "[gone]" : ifi->ifi_ifname);
                return;
        }

#ifdef OLDRAWSOCKET
        if ((size_t)i < sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr)) {
                syslog(LOG_ERR,
                    "packet size(%d) is too short", i);
                return;
        }

        ip = (struct ip6_hdr *)rcvmhdr.msg_iov[0].iov_base;
        icp = (struct icmp6_hdr *)(ip + 1); /* XXX: ext. hdr? */
#else
        if ((size_t)i < sizeof(struct icmp6_hdr)) {
                syslog(LOG_ERR, "packet size(%zd) is too short", i);
                return;
        }

        icp = (struct icmp6_hdr *)rcvmhdr.msg_iov[0].iov_base;
#endif

        switch (icp->icmp6_type) {
        case ND_ROUTER_SOLICIT:
                /*
                 * Message verification - RFC 4861 6.1.1
                 * XXX: these checks must be done in the kernel as well,
                 *      but we can't completely rely on them.
                 */
                if (*hlimp != 255) {
                        syslog(LOG_NOTICE,
                            "RS with invalid hop limit(%d) "
                            "received from %s on %s",
                            *hlimp,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            sizeof(ntopbuf)),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if (icp->icmp6_code) {
                        syslog(LOG_NOTICE,
                            "RS with invalid ICMP6 code(%d) "
                            "received from %s on %s",
                            icp->icmp6_code,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            sizeof(ntopbuf)),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if ((size_t)i < sizeof(struct nd_router_solicit)) {
                        syslog(LOG_NOTICE,
                            "RS from %s on %s does not have enough "
                            "length (len = %zd)",
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            sizeof(ntopbuf)),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf), i);
                        return;
                }
                rs_input(i, (struct nd_router_solicit *)icp, pi, &rcvfrom);
                break;
        case ND_ROUTER_ADVERT:
                /*
                 * Message verification - RFC 4861 6.1.2
                 * XXX: there's the same dilemma as above...
                 */
                if (!IN6_IS_ADDR_LINKLOCAL(&rcvfrom.sin6_addr)) {
                        syslog(LOG_NOTICE,
                            "RA with non-linklocal source address "
                            "received from %s on %s",
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr,
                            ntopbuf, sizeof(ntopbuf)),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if (*hlimp != 255) {
                        syslog(LOG_NOTICE,
                            "RA with invalid hop limit(%d) "
                            "received from %s on %s",
                            *hlimp,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            sizeof(ntopbuf)),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if (icp->icmp6_code) {
                        syslog(LOG_NOTICE,
                            "RA with invalid ICMP6 code(%d) "
                            "received from %s on %s",
                            icp->icmp6_code,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            sizeof(ntopbuf)),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if ((size_t)i < sizeof(struct nd_router_advert)) {
                        syslog(LOG_NOTICE,
                            "RA from %s on %s does not have enough "
                            "length (len = %zd)",
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            sizeof(ntopbuf)),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf), i);
                        return;
                }
                ra_input(i, (struct nd_router_advert *)icp, pi, &rcvfrom);
                break;
        case ICMP6_ROUTER_RENUMBERING:
                if (mcastif == NULL) {
                        syslog(LOG_ERR, "received a router renumbering "
                            "message, but not allowed to be accepted");
                        break;
                }
                rr_input(i, (struct icmp6_router_renum *)icp, pi, &rcvfrom,
                    &dst);
                break;
        default:
                /*
                 * Note that this case is POSSIBLE, especially just
                 * after invocation of the daemon. This is because we
                 * could receive message after opening the socket and
                 * before setting ICMP6 type filter(see sock_open()).
                 */
                syslog(LOG_ERR, "invalid icmp type(%d)", icp->icmp6_type);
                return;
        }
}

static void
rs_input(int len, struct nd_router_solicit *rs,
         struct in6_pktinfo *pi, struct sockaddr_in6 *from)
{
        char ntopbuf[INET6_ADDRSTRLEN];
        char ifnamebuf[IFNAMSIZ];
        union nd_opt ndopts;
        struct rainfo *rai;
        struct ifinfo *ifi;
        struct soliciter *sol;

        syslog(LOG_DEBUG,
            "<%s> RS received from %s on %s",
            __func__,
            inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf, sizeof(ntopbuf)),
            if_indextoname(pi->ipi6_ifindex, ifnamebuf));

        /* ND option check */
        memset(&ndopts, 0, sizeof(ndopts));
        TAILQ_INIT(&ndopts.opt_list);
        if (nd6_options((struct nd_opt_hdr *)(rs + 1),
                        len - sizeof(struct nd_router_solicit),
                        &ndopts, NDOPT_FLAG_SRCLINKADDR)) {
                syslog(LOG_INFO,
                    "<%s> ND option check failed for an RS from %s on %s",
                    __func__,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        /*
         * If the IP source address is the unspecified address, there
         * must be no source link-layer address option in the message.
         * (RFC 4861 6.1.1)
         */
        if (IN6_IS_ADDR_UNSPECIFIED(&from->sin6_addr) &&
            ndopts.opt_src_lladdr) {
                syslog(LOG_INFO,
                    "<%s> RS from unspecified src on %s has a link-layer"
                    " address option",
                    __func__, if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                goto done;
        }

        ifi = if_indextoifinfo(pi->ipi6_ifindex);
        if (ifi == NULL) {
                syslog(LOG_INFO,
                    "<%s> if (idx=%d) not found.  Why?",
                    __func__, pi->ipi6_ifindex);
                goto done;
        }
        rai = ifi->ifi_rainfo;
        if (rai == NULL) {
                syslog(LOG_INFO,
                       "<%s> RS received on non advertising interface(%s)",
                       __func__,
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                goto done;
        }

        rai->rai_ifinfo->ifi_rsinput++;

        /*
         * Decide whether to send RA according to the rate-limit
         * consideration.
         */

        /* record sockaddr waiting for RA, if possible */
        sol = (struct soliciter *)malloc(sizeof(*sol));
        if (sol) {
                sol->sol_addr = *from;
                /* XXX RFC 2553 need clarification on flowinfo */
                sol->sol_addr.sin6_flowinfo = 0;
                TAILQ_INSERT_TAIL(&rai->rai_soliciter, sol, sol_next);
        }

        /*
         * If there is already a waiting RS packet, don't
         * update the timer.
         */
        if (ifi->ifi_rs_waitcount++)
                goto done;

        set_short_delay(ifi);

  done:
        free_ndopts(&ndopts);
}

static void
set_short_delay(struct ifinfo *ifi)
{
        long delay;     /* must not be greater than 1000000 */
        struct timespec interval, now, min_delay, tm_tmp, *rest;

        if (ifi->ifi_ra_timer == NULL)
                return;
        /*
         * Compute a random delay. If the computed value
         * corresponds to a time later than the time the next
         * multicast RA is scheduled to be sent, ignore the random
         * delay and send the advertisement at the
         * already-scheduled time. RFC 4861 6.2.6
         */
        delay = arc4random_uniform(MAX_RA_DELAY_TIME);
        interval.tv_sec = 0;
        interval.tv_nsec = delay * 1000;
        rest = rtadvd_timer_rest(ifi->ifi_ra_timer);
        if (TS_CMP(rest, &interval, <)) {
                syslog(LOG_DEBUG, "<%s> random delay is larger than "
                    "the rest of the current timer", __func__);
                interval = *rest;
        }

        /*
         * If we sent a multicast Router Advertisement within
         * the last MIN_DELAY_BETWEEN_RAS seconds, schedule
         * the advertisement to be sent at a time corresponding to
         * MIN_DELAY_BETWEEN_RAS plus the random value after the
         * previous advertisement was sent.
         */
        clock_gettime(CLOCK_MONOTONIC_FAST, &now);
        TS_SUB(&now, &ifi->ifi_ra_lastsent, &tm_tmp);
        min_delay.tv_sec = MIN_DELAY_BETWEEN_RAS;
        min_delay.tv_nsec = 0;
        if (TS_CMP(&tm_tmp, &min_delay, <)) {
                TS_SUB(&min_delay, &tm_tmp, &min_delay);
                TS_ADD(&min_delay, &interval, &interval);
        }
        rtadvd_set_timer(&interval, ifi->ifi_ra_timer);
}

static int
check_accept_rtadv(int idx)
{
        struct ifinfo *ifi;

        TAILQ_FOREACH(ifi, &ifilist, ifi_next) {
                if (ifi->ifi_ifindex == idx)
                        break;
        }
        if (ifi == NULL) {
                syslog(LOG_DEBUG,
                    "<%s> if (idx=%d) not found.  Why?",
                    __func__, idx);
                return (0);
        }

        /*
         * RA_RECV: ND6_IFF_ACCEPT_RTADV
         * RA_SEND: ip6.forwarding
         */
        if (update_ifinfo_nd_flags(ifi) != 0) {
                syslog(LOG_ERR, "cannot get nd6 flags (idx=%d)", idx);
                return (0);
        }

        return (ifi->ifi_nd_flags & ND6_IFF_ACCEPT_RTADV);
}

static void
ra_input(int len, struct nd_router_advert *nra,
         struct in6_pktinfo *pi, struct sockaddr_in6 *from)
{
        struct rainfo *rai;
        struct ifinfo *ifi;
        char ntopbuf[INET6_ADDRSTRLEN];
        char ifnamebuf[IFNAMSIZ];
        union nd_opt ndopts;
        const char *on_off[] = {"OFF", "ON"};
        uint32_t reachabletime, retranstimer, mtu;
        int inconsistent = 0;
        int error;

        syslog(LOG_DEBUG, "<%s> RA received from %s on %s", __func__,
            inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf, sizeof(ntopbuf)),
            if_indextoname(pi->ipi6_ifindex, ifnamebuf));

        /* ND option check */
        memset(&ndopts, 0, sizeof(ndopts));
        TAILQ_INIT(&ndopts.opt_list);
        error = nd6_options((struct nd_opt_hdr *)(nra + 1),
            len - sizeof(struct nd_router_advert), &ndopts,
            NDOPT_FLAG_SRCLINKADDR | NDOPT_FLAG_PREFIXINFO | NDOPT_FLAG_MTU |
            NDOPT_FLAG_RDNSS | NDOPT_FLAG_DNSSL | NDOPT_FLAG_PREF64);
        if (error) {
                syslog(LOG_INFO,
                    "<%s> ND option check failed for an RA from %s on %s",
                    __func__,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), if_indextoname(pi->ipi6_ifindex,
                        ifnamebuf));
                return;
        }

        /*
         * RA consistency check according to RFC 4861 6.2.7
         */
        ifi = if_indextoifinfo(pi->ipi6_ifindex);
        if (ifi->ifi_rainfo == NULL) {
                syslog(LOG_INFO,
                    "<%s> received RA from %s on non-advertising"
                    " interface(%s)",
                    __func__,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), if_indextoname(pi->ipi6_ifindex,
                        ifnamebuf));
                goto done;
        }
        rai = ifi->ifi_rainfo;
        ifi->ifi_rainput++;
        syslog(LOG_DEBUG, "<%s> ifi->ifi_rainput = %" PRIu64, __func__,
            ifi->ifi_rainput);

        /* Cur Hop Limit value */
        if (nra->nd_ra_curhoplimit && rai->rai_hoplimit &&
            nra->nd_ra_curhoplimit != rai->rai_hoplimit) {
                syslog(LOG_NOTICE,
                    "CurHopLimit inconsistent on %s:"
                    " %d from %s, %d from us",
                    ifi->ifi_ifname, nra->nd_ra_curhoplimit,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), rai->rai_hoplimit);
                inconsistent++;
        }
        /* M flag */
        if ((nra->nd_ra_flags_reserved & ND_RA_FLAG_MANAGED) !=
            rai->rai_managedflg) {
                syslog(LOG_NOTICE,
                    "M flag inconsistent on %s:"
                    " %s from %s, %s from us",
                    ifi->ifi_ifname, on_off[!rai->rai_managedflg],
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), on_off[rai->rai_managedflg]);
                inconsistent++;
        }
        /* O flag */
        if ((nra->nd_ra_flags_reserved & ND_RA_FLAG_OTHER) !=
            rai->rai_otherflg) {
                syslog(LOG_NOTICE,
                    "O flag inconsistent on %s:"
                    " %s from %s, %s from us",
                    ifi->ifi_ifname, on_off[!rai->rai_otherflg],
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), on_off[rai->rai_otherflg]);
                inconsistent++;
        }
#ifdef DRAFT_IETF_6MAN_IPV6ONLY_FLAG
        /* S "IPv6-Only" (Six, Silence-IPv4) flag */
        if ((nra->nd_ra_flags_reserved & ND_RA_FLAG_IPV6_ONLY) !=
            rai->rai_ipv6onlyflg) {
                syslog(LOG_NOTICE,
                    "S flag inconsistent on %s:"
                    " %s from %s, %s from us",
                    ifi->ifi_ifname, on_off[!rai->rai_ipv6onlyflg],
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), on_off[rai->rai_ipv6onlyflg]);
                inconsistent++;
        }
#endif
        /* Reachable Time */
        reachabletime = ntohl(nra->nd_ra_reachable);
        if (reachabletime && rai->rai_reachabletime &&
            reachabletime != rai->rai_reachabletime) {
                syslog(LOG_NOTICE,
                    "ReachableTime inconsistent on %s:"
                    " %d from %s, %d from us",
                    ifi->ifi_ifname, reachabletime,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), rai->rai_reachabletime);
                inconsistent++;
        }
        /* Retrans Timer */
        retranstimer = ntohl(nra->nd_ra_retransmit);
        if (retranstimer && rai->rai_retranstimer &&
            retranstimer != rai->rai_retranstimer) {
                syslog(LOG_NOTICE,
                    "RetranceTimer inconsistent on %s:"
                    " %d from %s, %d from us",
                    ifi->ifi_ifname, retranstimer,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), rai->rai_retranstimer);
                inconsistent++;
        }
        /* Values in the MTU options */
        if (ndopts.opt_mtu) {
                mtu = ntohl(ndopts.opt_mtu->nd_opt_mtu_mtu);
                if (mtu && rai->rai_linkmtu && mtu != rai->rai_linkmtu) {
                        syslog(LOG_NOTICE,
                            "MTU option value inconsistent on %s:"
                            " %d from %s, %d from us",
                            ifi->ifi_ifname, mtu,
                            inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                                sizeof(ntopbuf)), rai->rai_linkmtu);
                        inconsistent++;
                }
        }
        /* Preferred and Valid Lifetimes for prefixes */
        {
                struct nd_optlist *nol;

                if (ndopts.opt_pi)
                        if (prefix_check(ndopts.opt_pi, rai, from))
                                inconsistent++;

                TAILQ_FOREACH(nol, &ndopts.opt_list, nol_next)
                        if (prefix_check((struct nd_opt_prefix_info *)nol->nol_opt,
                                rai, from))
                                inconsistent++;
        }

        if (inconsistent)
                ifi->ifi_rainconsistent++;

  done:
        free_ndopts(&ndopts);
}

static uint32_t
udiff(uint32_t u, uint32_t v)
{
        return (u >= v ? u - v : v - u);
}

/* return a non-zero value if the received prefix is inconsistent with ours */
static int
prefix_check(struct nd_opt_prefix_info *pinfo,
        struct rainfo *rai, struct sockaddr_in6 *from)
{
        struct ifinfo *ifi;
        uint32_t preferred_time, valid_time;
        struct prefix *pfx;
        int inconsistent = 0;
        char ntopbuf[INET6_ADDRSTRLEN];
        char prefixbuf[INET6_ADDRSTRLEN];
        struct timespec now;

#if 0                           /* impossible */
        if (pinfo->nd_opt_pi_type != ND_OPT_PREFIX_INFORMATION)
                return (0);
#endif
        ifi = rai->rai_ifinfo;
        /*
         * log if the adveritsed prefix has link-local scope(sanity check?)
         */
        if (IN6_IS_ADDR_LINKLOCAL(&pinfo->nd_opt_pi_prefix))
                syslog(LOG_INFO,
                    "<%s> link-local prefix %s/%d is advertised "
                    "from %s on %s",
                    __func__,
                    inet_ntop(AF_INET6, &pinfo->nd_opt_pi_prefix, prefixbuf,
                        sizeof(prefixbuf)),
                    pinfo->nd_opt_pi_prefix_len,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), ifi->ifi_ifname);

        if ((pfx = find_prefix(rai, &pinfo->nd_opt_pi_prefix,
                pinfo->nd_opt_pi_prefix_len)) == NULL) {
                syslog(LOG_INFO,
                    "<%s> prefix %s/%d from %s on %s is not in our list",
                    __func__,
                    inet_ntop(AF_INET6, &pinfo->nd_opt_pi_prefix, prefixbuf,
                        sizeof(prefixbuf)),
                    pinfo->nd_opt_pi_prefix_len,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), ifi->ifi_ifname);
                return (0);
        }

        preferred_time = ntohl(pinfo->nd_opt_pi_preferred_time);
        if (pfx->pfx_pltimeexpire) {
                /*
                 * The lifetime is decremented in real time, so we should
                 * compare the expiration time.
                 * (RFC 2461 Section 6.2.7.)
                 * XXX: can we really expect that all routers on the link
                 * have synchronized clocks?
                 */
                clock_gettime(CLOCK_MONOTONIC_FAST, &now);
                preferred_time += now.tv_sec;

                if (!pfx->pfx_timer && rai->rai_clockskew &&
                    udiff(preferred_time, pfx->pfx_pltimeexpire) > rai->rai_clockskew) {
                        syslog(LOG_INFO,
                            "<%s> preferred lifetime for %s/%d"
                            " (decr. in real time) inconsistent on %s:"
                            " %" PRIu32 " from %s, %" PRIu32 " from us",
                            __func__,
                            inet_ntop(AF_INET6, &pinfo->nd_opt_pi_prefix, prefixbuf,
                                sizeof(prefixbuf)),
                            pinfo->nd_opt_pi_prefix_len,
                            ifi->ifi_ifname, preferred_time,
                            inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                                sizeof(ntopbuf)), pfx->pfx_pltimeexpire);
                        inconsistent++;
                }
        } else if (!pfx->pfx_timer && preferred_time != pfx->pfx_preflifetime)
                syslog(LOG_INFO,
                    "<%s> preferred lifetime for %s/%d"
                    " inconsistent on %s:"
                    " %d from %s, %d from us",
                    __func__,
                    inet_ntop(AF_INET6, &pinfo->nd_opt_pi_prefix, prefixbuf,
                        sizeof(prefixbuf)),
                    pinfo->nd_opt_pi_prefix_len,
                    ifi->ifi_ifname, preferred_time,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), pfx->pfx_preflifetime);

        valid_time = ntohl(pinfo->nd_opt_pi_valid_time);
        if (pfx->pfx_vltimeexpire) {
                clock_gettime(CLOCK_MONOTONIC_FAST, &now);
                valid_time += now.tv_sec;

                if (!pfx->pfx_timer && rai->rai_clockskew &&
                    udiff(valid_time, pfx->pfx_vltimeexpire) > rai->rai_clockskew) {
                        syslog(LOG_INFO,
                            "<%s> valid lifetime for %s/%d"
                            " (decr. in real time) inconsistent on %s:"
                            " %d from %s, %" PRIu32 " from us",
                            __func__,
                            inet_ntop(AF_INET6, &pinfo->nd_opt_pi_prefix, prefixbuf,
                                sizeof(prefixbuf)),
                            pinfo->nd_opt_pi_prefix_len,
                            ifi->ifi_ifname, preferred_time,
                            inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                                sizeof(ntopbuf)), pfx->pfx_vltimeexpire);
                        inconsistent++;
                }
        } else if (!pfx->pfx_timer && valid_time != pfx->pfx_validlifetime) {
                syslog(LOG_INFO,
                    "<%s> valid lifetime for %s/%d"
                    " inconsistent on %s:"
                    " %d from %s, %d from us",
                    __func__,
                    inet_ntop(AF_INET6, &pinfo->nd_opt_pi_prefix, prefixbuf,
                        sizeof(prefixbuf)),
                    pinfo->nd_opt_pi_prefix_len,
                    ifi->ifi_ifname, valid_time,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf,
                        sizeof(ntopbuf)), pfx->pfx_validlifetime);
                inconsistent++;
        }

        return (inconsistent);
}

struct prefix *
find_prefix(struct rainfo *rai, struct in6_addr *prefix, int plen)
{
        struct prefix *pfx;
        int bytelen, bitlen;
        char bitmask;

        TAILQ_FOREACH(pfx, &rai->rai_prefix, pfx_next) {
                if (plen != pfx->pfx_prefixlen)
                        continue;

                bytelen = plen / 8;
                bitlen = plen % 8;
                bitmask = 0xff << (8 - bitlen);

                if (memcmp((void *)prefix, (void *)&pfx->pfx_prefix, bytelen))
                        continue;

                if (bitlen == 0 ||
                    ((prefix->s6_addr[bytelen] & bitmask) ==
                     (pfx->pfx_prefix.s6_addr[bytelen] & bitmask))) {
                        return (pfx);
                }
        }

        return (NULL);
}

/* check if p0/plen0 matches p1/plen1; return 1 if matches, otherwise 0. */
int
prefix_match(struct in6_addr *p0, int plen0,
        struct in6_addr *p1, int plen1)
{
        int bytelen, bitlen;
        char bitmask;

        if (plen0 < plen1)
                return (0);

        bytelen = plen1 / 8;
        bitlen = plen1 % 8;
        bitmask = 0xff << (8 - bitlen);

        if (memcmp((void *)p0, (void *)p1, bytelen))
                return (0);

        if (bitlen == 0 ||
            ((p0->s6_addr[bytelen] & bitmask) ==
             (p1->s6_addr[bytelen] & bitmask))) {
                return (1);
        }

        return (0);
}

static int
nd6_options(struct nd_opt_hdr *hdr, int limit,
        union nd_opt *ndopts, uint32_t optflags)
{
        int optlen = 0;

        for (; limit > 0; limit -= optlen) {
                if ((size_t)limit < sizeof(struct nd_opt_hdr)) {
                        syslog(LOG_INFO, "<%s> short option header", __func__);
                        goto bad;
                }

                hdr = (struct nd_opt_hdr *)((caddr_t)hdr + optlen);
                if (hdr->nd_opt_len == 0) {
                        syslog(LOG_INFO,
                            "<%s> bad ND option length(0) (type = %d)",
                            __func__, hdr->nd_opt_type);
                        goto bad;
                }
                optlen = hdr->nd_opt_len << 3;
                if (optlen > limit) {
                        syslog(LOG_INFO, "<%s> short option", __func__);
                        goto bad;
                }

                if (hdr->nd_opt_type > ND_OPT_MTU &&
                    hdr->nd_opt_type != ND_OPT_RDNSS &&
                    hdr->nd_opt_type != ND_OPT_DNSSL &&
                    hdr->nd_opt_type != ND_OPT_PREF64) {
                        syslog(LOG_INFO, "<%s> unknown ND option(type %d)",
                            __func__, hdr->nd_opt_type);
                        continue;
                }

                if ((ndopt_flags[hdr->nd_opt_type] & optflags) == 0) {
                        syslog(LOG_INFO, "<%s> unexpected ND option(type %d)",
                            __func__, hdr->nd_opt_type);
                        continue;
                }

                /*
                 * Option length check.  Do it here for all fixed-length
                 * options.
                 */
                switch (hdr->nd_opt_type) {
                case ND_OPT_MTU:
                        if (optlen == sizeof(struct nd_opt_mtu))
                                break;
                        goto skip;
                case ND_OPT_RDNSS:
                        if (optlen >= 24 &&
                            (optlen - sizeof(struct nd_opt_rdnss)) % 16 == 0)
                                break;
                        goto skip;
                case ND_OPT_DNSSL:
                        if (optlen >= 16 &&
                            (optlen - sizeof(struct nd_opt_dnssl)) % 8 == 0)
                                break;
                        goto skip;
                case ND_OPT_PREFIX_INFORMATION:
                        if (optlen == sizeof(struct nd_opt_prefix_info))
                                break;
skip:
                        syslog(LOG_INFO, "<%s> invalid option length",
                            __func__);
                        continue;
                }

                switch (hdr->nd_opt_type) {
                case ND_OPT_TARGET_LINKADDR:
                case ND_OPT_REDIRECTED_HEADER:
                case ND_OPT_RDNSS:
                case ND_OPT_DNSSL:
                case ND_OPT_PREF64:
                        break;  /* we don't care about these options */
                case ND_OPT_SOURCE_LINKADDR:
                case ND_OPT_MTU:
                        if (ndopts->opt_array[hdr->nd_opt_type]) {
                                syslog(LOG_INFO,
                                    "<%s> duplicated ND option (type = %d)",
                                    __func__, hdr->nd_opt_type);
                        }
                        ndopts->opt_array[hdr->nd_opt_type] = hdr;
                        break;
                case ND_OPT_PREFIX_INFORMATION:
                {
                        struct nd_optlist *nol;

                        if (ndopts->opt_pi == 0) {
                                ndopts->opt_pi =
                                    (struct nd_opt_prefix_info *)hdr;
                                continue;
                        }
                        nol = malloc(sizeof(*nol));
                        if (nol == NULL) {
                                syslog(LOG_ERR, "<%s> can't allocate memory",
                                    __func__);
                                goto bad;
                        }
                        nol->nol_opt = hdr;
                        TAILQ_INSERT_TAIL(&(ndopts->opt_list), nol, nol_next);

                        break;
                }
                default:        /* impossible */
                        break;
                }
        }

        return (0);

  bad:
        free_ndopts(ndopts);

        return (-1);
}

static void
free_ndopts(union nd_opt *ndopts)
{
        struct nd_optlist *nol;

        while ((nol = TAILQ_FIRST(&ndopts->opt_list)) != NULL) {
                TAILQ_REMOVE(&ndopts->opt_list, nol, nol_next);
                free(nol);
        }
}

void
sock_open(struct sockinfo *s)
{
        struct icmp6_filter filt;
        int on;
        /* XXX: should be max MTU attached to the node */
        static char answer[1500];

        syslog(LOG_DEBUG, "<%s> enter", __func__);

        if (s == NULL) {
                syslog(LOG_ERR, "<%s> internal error", __func__);
                exit(1);
        }
        rcvcmsgbuflen = CMSG_SPACE(sizeof(struct in6_pktinfo)) +
            CMSG_SPACE(sizeof(int));
        rcvcmsgbuf = (char *)malloc(rcvcmsgbuflen);
        if (rcvcmsgbuf == NULL) {
                syslog(LOG_ERR, "<%s> not enough core", __func__);
                exit(1);
        }

        sndcmsgbuflen = CMSG_SPACE(sizeof(struct in6_pktinfo)) +
            CMSG_SPACE(sizeof(int));
        sndcmsgbuf = (char *)malloc(sndcmsgbuflen);
        if (sndcmsgbuf == NULL) {
                syslog(LOG_ERR, "<%s> not enough core", __func__);
                exit(1);
        }

        if ((s->si_fd = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0) {
                syslog(LOG_ERR, "<%s> socket: %s", __func__, strerror(errno));
                exit(1);
        }
        /* specify to tell receiving interface */
        on = 1;
        if (setsockopt(s->si_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on,
            sizeof(on)) < 0) {
                syslog(LOG_ERR, "<%s> IPV6_RECVPKTINFO: %s", __func__,
                    strerror(errno));
                exit(1);
        }
        on = 1;
        /* specify to tell value of hoplimit field of received IP6 hdr */
        if (setsockopt(s->si_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on,
                sizeof(on)) < 0) {
                syslog(LOG_ERR, "<%s> IPV6_RECVHOPLIMIT: %s", __func__,
                    strerror(errno));
                exit(1);
        }
        ICMP6_FILTER_SETBLOCKALL(&filt);
        ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
        ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
        if (mcastif != NULL)
                ICMP6_FILTER_SETPASS(ICMP6_ROUTER_RENUMBERING, &filt);

        if (setsockopt(s->si_fd, IPPROTO_ICMPV6, ICMP6_FILTER, &filt,
            sizeof(filt)) < 0) {
                syslog(LOG_ERR, "<%s> IICMP6_FILTER: %s",
                    __func__, strerror(errno));
                exit(1);
        }

        /* initialize msghdr for receiving packets */
        rcviov[0].iov_base = (caddr_t)answer;
        rcviov[0].iov_len = sizeof(answer);
        rcvmhdr.msg_name = (caddr_t)&rcvfrom;
        rcvmhdr.msg_namelen = sizeof(rcvfrom);
        rcvmhdr.msg_iov = rcviov;
        rcvmhdr.msg_iovlen = 1;
        rcvmhdr.msg_control = (caddr_t) rcvcmsgbuf;
        rcvmhdr.msg_controllen = rcvcmsgbuflen;

        /* initialize msghdr for sending packets */
        sndmhdr.msg_namelen = sizeof(struct sockaddr_in6);
        sndmhdr.msg_iov = sndiov;
        sndmhdr.msg_iovlen = 1;
        sndmhdr.msg_control = (caddr_t)sndcmsgbuf;
        sndmhdr.msg_controllen = sndcmsgbuflen;
}

/* open a routing socket to watch the routing table */
static void
rtsock_open(struct sockinfo *s)
{
        if (s == NULL) {
                syslog(LOG_ERR, "<%s> internal error", __func__);
                exit(1);
        }
        if ((s->si_fd = socket(PF_ROUTE, SOCK_RAW, 0)) < 0) {
                syslog(LOG_ERR,
                    "<%s> socket: %s", __func__, strerror(errno));
                exit(1);
        }
}

struct ifinfo *
if_indextoifinfo(int idx)
{
        struct ifinfo *ifi;
        char *name, name0[IFNAMSIZ];

        /* Check if the interface has a valid name or not. */
        if (if_indextoname(idx, name0) == NULL)
                return (NULL);

        TAILQ_FOREACH(ifi, &ifilist, ifi_next) {
                if (ifi->ifi_ifindex == idx)
                        return (ifi);
        }

        if (ifi != NULL)
                syslog(LOG_DEBUG, "<%s> ifi found (idx=%d)",
                    __func__, idx);
        else
                syslog(LOG_DEBUG, "<%s> ifi not found (idx=%d)",
                    __func__, idx);

        return (NULL);          /* search failed */
}

void
ra_output(struct ifinfo *ifi)
{
        int i;
        struct cmsghdr *cm;
        struct in6_pktinfo *pi;
        struct soliciter *sol;
        struct rainfo *rai;

        switch (ifi->ifi_state) {
        case IFI_STATE_CONFIGURED:
                rai = ifi->ifi_rainfo;
                break;
        case IFI_STATE_TRANSITIVE:
                rai = ifi->ifi_rainfo_trans;
                break;
        case IFI_STATE_UNCONFIGURED:
                syslog(LOG_DEBUG, "<%s> %s is unconfigured.  "
                    "Skip sending RAs.",
                    __func__, ifi->ifi_ifname);
                return;
        default:
                rai = NULL;
        }
        if (rai == NULL) {
                syslog(LOG_DEBUG, "<%s> rainfo is NULL on %s."
                    "Skip sending RAs.",
                    __func__, ifi->ifi_ifname);
                return;
        }
        if (!(ifi->ifi_flags & IFF_UP)) {
                syslog(LOG_DEBUG, "<%s> %s is not up.  "
                    "Skip sending RAs.",
                    __func__, ifi->ifi_ifname);
                return;
        }
        /*
         * Check lifetime, ACCEPT_RTADV flag, and ip6.forwarding.
         *
         * (lifetime == 0) = output
         * (lifetime != 0 && (check_accept_rtadv()) = no output
         *
         * Basically, hosts MUST NOT send Router Advertisement
         * messages at any time (RFC 4861, Section 6.2.3). However, it
         * would sometimes be useful to allow hosts to advertise some
         * parameters such as prefix information and link MTU. Thus,
         * we allow hosts to invoke rtadvd only when router lifetime
         * (on every advertising interface) is explicitly set
         * zero. (see also the above section)
         */
        syslog(LOG_DEBUG,
            "<%s> check lifetime=%d, ACCEPT_RTADV=%d, ip6.forwarding=%d "
            "on %s", __func__,
            rai->rai_lifetime,
            check_accept_rtadv(ifi->ifi_ifindex),
            getinet6sysctl(IPV6CTL_FORWARDING),
            ifi->ifi_ifname);

        if (rai->rai_lifetime != 0) {
                if (getinet6sysctl(IPV6CTL_FORWARDING) == 0) {
                        syslog(LOG_ERR,
                            "non-zero lifetime RA "
                            "but net.inet6.ip6.forwarding=0.  "
                            "Ignored.");
                        return;
                }
                if (check_accept_rtadv(ifi->ifi_ifindex)) {
                        syslog(LOG_ERR,
                            "non-zero lifetime RA "
                            "on RA receiving interface %s."
                            "  Ignored.", ifi->ifi_ifname);
                        return;
                }
        }

        make_packet(rai);       /* XXX: inefficient */

        sndmhdr.msg_name = (caddr_t)&sin6_linklocal_allnodes;
        sndmhdr.msg_iov[0].iov_base = (caddr_t)rai->rai_ra_data;
        sndmhdr.msg_iov[0].iov_len = rai->rai_ra_datalen;

        cm = CMSG_FIRSTHDR(&sndmhdr);
        /* specify the outgoing interface */
        cm->cmsg_level = IPPROTO_IPV6;
        cm->cmsg_type = IPV6_PKTINFO;
        cm->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
        pi = (struct in6_pktinfo *)CMSG_DATA(cm);
        memset(&pi->ipi6_addr, 0, sizeof(pi->ipi6_addr));       /*XXX*/
        pi->ipi6_ifindex = ifi->ifi_ifindex;

        /* specify the hop limit of the packet */
        {
                int hoplimit = 255;

                cm = CMSG_NXTHDR(&sndmhdr, cm);
                cm->cmsg_level = IPPROTO_IPV6;
                cm->cmsg_type = IPV6_HOPLIMIT;
                cm->cmsg_len = CMSG_LEN(sizeof(int));
                memcpy(CMSG_DATA(cm), &hoplimit, sizeof(int));
        }

        syslog(LOG_DEBUG,
            "<%s> send RA on %s, # of RS waitings = %d",
            __func__, ifi->ifi_ifname, ifi->ifi_rs_waitcount);

        i = sendmsg(sock.si_fd, &sndmhdr, 0);

        if (i < 0 || (size_t)i != rai->rai_ra_datalen)  {
                if (i < 0) {
                        syslog(LOG_ERR, "<%s> sendmsg on %s: %s",
                            __func__, ifi->ifi_ifname,
                            strerror(errno));
                }
        }

        /*
         * unicast advertisements
         * XXX commented out.  reason: though spec does not forbit it, unicast
         * advert does not really help
         */
        while ((sol = TAILQ_FIRST(&rai->rai_soliciter)) != NULL) {
                TAILQ_REMOVE(&rai->rai_soliciter, sol, sol_next);
                free(sol);
        }

        /* update timestamp */
        clock_gettime(CLOCK_MONOTONIC_FAST, &ifi->ifi_ra_lastsent);

        /* update counter */
        ifi->ifi_rs_waitcount = 0;
        ifi->ifi_raoutput++;

        switch (ifi->ifi_state) {
        case IFI_STATE_CONFIGURED:
                if (ifi->ifi_burstcount > 0)
                        ifi->ifi_burstcount--;
                break;
        case IFI_STATE_TRANSITIVE:
                ifi->ifi_burstcount--;
                if (ifi->ifi_burstcount == 0) {
                        if (ifi->ifi_rainfo == ifi->ifi_rainfo_trans) {
                                /* Initial burst finished. */
                                if (ifi->ifi_rainfo_trans != NULL)
                                        ifi->ifi_rainfo_trans = NULL;
                        }

                        /* Remove burst RA information */
                        if (ifi->ifi_rainfo_trans != NULL) {
                                rm_rainfo(ifi->ifi_rainfo_trans);
                                ifi->ifi_rainfo_trans = NULL;
                        }

                        if (ifi->ifi_rainfo != NULL) {
                                /*
                                 * TRANSITIVE -> CONFIGURED
                                 *
                                 * After initial burst or transition from
                                 * one configuration to another,
                                 * ifi_rainfo always points to the next RA
                                 * information.
                                 */
                                ifi->ifi_state = IFI_STATE_CONFIGURED;
                                syslog(LOG_DEBUG,
                                    "<%s> ifname=%s marked as "
                                    "CONFIGURED.", __func__,
                                    ifi->ifi_ifname);
                        } else {
                                /*
                                 * TRANSITIVE -> UNCONFIGURED
                                 *
                                 * If ifi_rainfo points to NULL, this
                                 * interface is shutting down.
                                 *
                                 */
                                int error;

                                ifi->ifi_state = IFI_STATE_UNCONFIGURED;
                                syslog(LOG_DEBUG,
                                    "<%s> ifname=%s marked as "
                                    "UNCONFIGURED.", __func__,
                                    ifi->ifi_ifname);
                                error = sock_mc_leave(&sock,
                                    ifi->ifi_ifindex);
                                if (error)
                                        exit(1);
                        }
                }
                break;
        }
}

/* process RA timer */
struct rtadvd_timer *
ra_timeout(void *arg)
{
        struct ifinfo *ifi;

        ifi = (struct ifinfo *)arg;
        syslog(LOG_DEBUG, "<%s> RA timer on %s is expired",
            __func__, ifi->ifi_ifname);

        ra_output(ifi);

        return (ifi->ifi_ra_timer);
}

/* update RA timer */
void
ra_timer_update(void *arg, struct timespec *tm)
{
        uint16_t interval;
        struct rainfo *rai;
        struct ifinfo *ifi;

        ifi = (struct ifinfo *)arg;
        rai = ifi->ifi_rainfo;
        interval = 0;

        switch (ifi->ifi_state) {
        case IFI_STATE_UNCONFIGURED:
                return;
                break;
        case IFI_STATE_CONFIGURED:
                /*
                 * Whenever a multicast advertisement is sent from
                 * an interface, the timer is reset to a
                 * uniformly-distributed random value between the
                 * interface's configured MinRtrAdvInterval and
                 * MaxRtrAdvInterval (RFC4861 6.2.4).
                 */
                interval = rai->rai_mininterval;
                interval += arc4random_uniform(rai->rai_maxinterval -
                    rai->rai_mininterval);
                break;
        case IFI_STATE_TRANSITIVE:
                /*
                 * For the first few advertisements (up to
                 * MAX_INITIAL_RTR_ADVERTISEMENTS), if the randomly chosen
                 * interval is greater than
                 * MAX_INITIAL_RTR_ADVERT_INTERVAL, the timer SHOULD be
                 * set to MAX_INITIAL_RTR_ADVERT_INTERVAL instead.  (RFC
                 * 4861 6.2.4)
                 *
                 * In such cases, the router SHOULD transmit one or more
                 * (but not more than MAX_FINAL_RTR_ADVERTISEMENTS) final
                 * multicast Router Advertisements on the interface with a
                 * Router Lifetime field of zero.  (RFC 4861 6.2.5)
                 */
                interval = ifi->ifi_burstinterval;
                break;
        }

        tm->tv_sec = interval;
        tm->tv_nsec = 0;

        syslog(LOG_DEBUG,
            "<%s> RA timer on %s is set to %ld:%ld",
            __func__, ifi->ifi_ifname,
            (long int)tm->tv_sec, (long int)tm->tv_nsec / 1000);
}