/*      $NetBSD: rtadvd.c,v 1.84 2026/06/10 21:30:06 andvar Exp $       */
/*      $KAME: rtadvd.c,v 1.92 2005/10/17 14:40:02 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.
 */

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/time.h>
#include <sys/queue.h>

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

#include <arpa/inet.h>

#include <time.h>
#include <unistd.h>
#include <stdio.h>
#include <err.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include <signal.h>
#include <stdarg.h>
#ifdef __NetBSD__
#include <util.h>
#endif
#include <poll.h>
#include <pwd.h>

#include "rtadvd.h"
#include "advcap.h"
#include "timer.h"
#include "if.h"
#include "config.h"
#include "dump.h"
#include "logit.h"
#include "prog_ops.h"
#include "expandm.h"

struct msghdr rcvmhdr;
static unsigned char *rcvcmsgbuf;
static size_t rcvcmsgbuflen;
static unsigned char *sndcmsgbuf;
static size_t sndcmsgbuflen;
volatile sig_atomic_t do_dump;
volatile sig_atomic_t do_reconf;
volatile sig_atomic_t do_die;
struct msghdr sndmhdr;
struct iovec rcviov[2];
struct iovec sndiov[2];
struct sockaddr_in6 rcvfrom;
static const char *dumpfilename = "/var/run/rtadvd.dump"; /* XXX configurable */
int sock;
int rtsock = -1;
int Cflag = 0, dflag = 0, sflag = 0, Dflag;
static int after_daemon = 0;

static char **if_argv;
static int if_argc;

char *conffile = NULL;

struct ralist_head_t ralist = TAILQ_HEAD_INITIALIZER(ralist);

struct nd_optlist {
        TAILQ_ENTRY(nd_optlist) next;
        struct nd_opt_hdr *opt;
};
union nd_opts {
        struct nd_opt_hdr *nd_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) list;
        } nd_opt_each;
};
#define nd_opts_src_lladdr      nd_opt_each.src_lladdr
#define nd_opts_tgt_lladdr      nd_opt_each.tgt_lladdr
#define nd_opts_pi              nd_opt_each.pi
#define nd_opts_rh              nd_opt_each.rh
#define nd_opts_mtu             nd_opt_each.mtu
#define nd_opts_list            nd_opt_each.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)

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,
};

struct sockaddr_in6 sin6_linklocal_allnodes = {
        .sin6_len =     sizeof(sin6_linklocal_allnodes),
        .sin6_family =  AF_INET6,
        .sin6_addr =    IN6ADDR_LINKLOCAL_ALLNODES_INIT,
};
#ifdef notdef
struct sockaddr_in6 sin6_linklocal_allrouters = {
        .sin6_len =     sizeof(sin6_linklocal_allrouters),
        .sin6_family =  AF_INET6,
        .sin6_addr =    IN6ADDR_LINKLOCAL_ALLROUTERS_INIT,
};
#endif
struct sockaddr_in6 sin6_sitelocal_allrouters = {
        .sin6_len =     sizeof(sin6_sitelocal_allrouters),
        .sin6_family =  AF_INET6,
        .sin6_addr =    IN6ADDR_SITELOCAL_ALLROUTERS_INIT,
};

static void set_die(int);
static void die(void);
static void set_reconf(int);
static void sock_open(void);
static void rtsock_open(void);
static void rtadvd_input(void);
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 struct rainfo *ra_output(struct rainfo *, bool);
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_opts *, uint32_t);
static void free_ndopts(union nd_opts *);
static void rtmsg_input(void);
static void rtadvd_set_dump_file(int);

int
main(int argc, char *argv[])
{
        struct pollfd set[2];
        struct timespec *timeout;
        int i, ch;
        int fflag = 0, logopt;
        struct passwd *pw;
        const char *pidfilepath = NULL;
        pid_t pid;

        /* get command line options and arguments */
#define OPTIONS "Cc:dDfp:s"
        while ((ch = getopt(argc, argv, OPTIONS)) != -1) {
#undef OPTIONS
                switch (ch) {
                case 'c':
                        conffile = optarg;
                        break;
                case 'C':
                        Cflag++;
                        break;
                case 'd':
                        dflag++;
                        break;
                case 'D':
                        Dflag++;
                        break;
                case 'f':
                        fflag = 1;
                        break;
                case 'p':
                        pidfilepath = optarg;
                        break;
                case 's':
                        sflag = 1;
                        break;
                }
        }
        argc -= optind;
        argv += optind;
        if (argc == 0) {
                fprintf(stderr, "Usage: %s [-CDdfs] [-c conffile]"
                    " [-p pidfile] interface ...\n", getprogname());
                return EXIT_FAILURE;
        }

        if ((pid = pidfile_lock(pidfilepath)) != 0) {
                if (pid == -1) {
                        logit(LOG_ERR, "pidfile_lock: %m");
                } else {
                        logit(LOG_ERR, "Another instance of `%s' is running "
                            "(pid %d); exiting.", getprogname(), pid);
                }
                return EXIT_FAILURE;
        }

        if (prog_init && prog_init() == -1)
                err(EXIT_FAILURE, "init failed");

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

        /* set log level */
        if (dflag == 0)
                (void)setlogmask(LOG_UPTO(LOG_ERR));
        if (dflag == 1)
                (void)setlogmask(LOG_UPTO(LOG_INFO));

        errno = 0; /* Ensure errno is 0 so we know if getpwnam errors or not */
        if ((pw = getpwnam(RTADVD_USER)) == NULL) {
                if (errno == 0)
                        logit(LOG_ERR,
                            "user %s does not exist, aborting",
                            RTADVD_USER);
                else
                        logit(LOG_ERR, "getpwnam: %s: %m", RTADVD_USER);
                return EXIT_FAILURE;
        }

        /* timer initialization */
        rtadvd_timer_init();

        if_argc = argc;
        if_argv = argv;
        while (argc--)
                getconfig(*argv++, 1);

        if (!fflag) {
                prog_daemon(1, 0);
                after_daemon = 1;
                if (pidfile_lock(pidfilepath) != 0)
                        logit(LOG_ERR, " pidfile_lock: %m");
        }

        sock_open();

        set[0].fd = sock;
        set[0].events = POLLIN;
        if (sflag == 0) {
                rtsock_open();
                set[1].fd = rtsock;
                set[1].events = POLLIN;
        } else
                set[1].fd = -1;

        logit(LOG_INFO, "dropping privileges to %s", RTADVD_USER);
        tzset();
        if (prog_chroot(pw->pw_dir) == -1) {
                logit(LOG_ERR, "chroot: %s: %m", pw->pw_dir);
                return EXIT_FAILURE;
        }
        if (prog_chdir("/") == -1) {
                logit(LOG_ERR, "chdir: /: %m");
                return EXIT_FAILURE;
        }
        if (prog_setgroups(1, &pw->pw_gid) == -1 ||
            prog_setgid(pw->pw_gid) == -1 ||
            prog_setuid(pw->pw_uid) == -1)
        {
                logit(LOG_ERR, "failed to drop privileges: %m");
                return EXIT_FAILURE;
        }

        signal(SIGINT, set_die);
        signal(SIGTERM, set_die);
        signal(SIGHUP, set_reconf);
        signal(SIGUSR1, rtadvd_set_dump_file);

        for (;;) {
                if (do_dump) {  /* SIGUSR1 */
                        do_dump = 0;
                        rtadvd_dump_file(dumpfilename);
                }

                if (do_reconf) { /* SIGHUP */
                        do_reconf = 0;
                        logit(LOG_INFO, "%s: reloading config on SIGHUP",
                               __func__);
                        argc = if_argc;
                        argv = if_argv;
                        while (argc--)
                                getconfig(*argv++, 0);
                }

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

                if (do_die) {
                        die();
                        /*NOTREACHED*/
                }

                if (timeout != NULL) {
                        logit(LOG_DEBUG,
                            "%s: set timer to %jd:%jd. waiting for "
                            "inputs or timeout", __func__,
                            (intmax_t)timeout->tv_sec,
                            (intmax_t)timeout->tv_nsec);
                } else {
                        logit(LOG_DEBUG,
                            "%s: there's no timer. waiting for inputs",
                            __func__);
                }

                if ((i = prog_poll(set, 2, timeout ? (timeout->tv_sec * 1000 +
                    (timeout->tv_nsec + 999999) / 1000000) : INFTIM)) == -1)
                {
                        /* EINTR would occur upon SIGUSR1 for status dump */
                        if (errno == EINTR) {
                                if (do_die)
                                        die();
                                continue;
                        }

                        logit(LOG_ERR, "%s: poll: %m", __func__);
                        if (Dflag)
                                exit(1);
                }
                if (i == 0)     /* timeout */
                        continue;
                if (rtsock != -1 && set[1].revents & POLLIN)
                        rtmsg_input();
                if (set[0].revents & POLLIN)
                        rtadvd_input();
        }
        return EXIT_SUCCESS;    /* NOTREACHED */
}

static void
rtadvd_set_dump_file(__unused int sig)
{

        do_dump = 1;
}

static void
set_reconf(__unused int sig)
{

        do_reconf = 1;
}

static void
set_die(__unused int sig)
{

        do_die = 1;
}

static void
die(void)
{
        static int waiting;
        struct rainfo *rai, *ran;
        struct rdnss *rdnss;
        struct dnssl *dnssl;

        if (waiting) {
                if (TAILQ_FIRST(&ralist)) {
                        logit(LOG_INFO,
                               "%s: waiting for expiration of all RA timers",
                               __func__);
                        return;
                }
                logit(LOG_NOTICE, "%s: gracefully terminated", __func__);
                free(rcvcmsgbuf);
                free(sndcmsgbuf);
                exit(EXIT_SUCCESS);
                /* NOT REACHED */
        }

        if (TAILQ_FIRST(&ralist) == NULL) {
                logit(LOG_NOTICE, "%s: gracefully terminated", __func__);
                exit(EXIT_SUCCESS);
                /* NOT REACHED */
        }

        waiting = 1;
        logit(LOG_NOTICE, "%s: final RA transmission started", __func__);

        TAILQ_FOREACH_SAFE(rai, &ralist, next, ran) {
                if (rai->leaving) {
                        TAILQ_REMOVE(&ralist, rai, next);
                        TAILQ_INSERT_HEAD(&ralist, rai->leaving, next);
                        rai->leaving->leaving = rai->leaving;
                        rai->leaving->leaving_for = rai->leaving;
                        free_rainfo(rai);
                        continue;
                }
                rai->lifetime = 0;
                TAILQ_FOREACH(rdnss, &rai->rdnss, next)
                        rdnss->lifetime = 0;
                TAILQ_FOREACH(dnssl, &rai->dnssl, next)
                        dnssl->lifetime = 0;
                make_packet(rai);
                rai->leaving = rai;
                rai->leaving_for = rai;
                rai->initcounter = MAX_INITIAL_RTR_ADVERTISEMENTS;
                rai->mininterval = MIN_DELAY_BETWEEN_RAS;
                rai->maxinterval = MIN_DELAY_BETWEEN_RAS;
                rai->leaving_adv = MAX_FINAL_RTR_ADVERTISEMENTS;
                ra_output(rai, false);
                ra_timer_update(rai, &rai->timer->tm);
                rtadvd_set_timer(&rai->timer->tm, rai->timer);
        }
        exit(EXIT_SUCCESS);
}

static void
ra_timer_reset(struct rainfo *rai)
{

        rtadvd_remove_timer(&rai->timer);
        rai->timer = rtadvd_add_timer(ra_timeout, ra_timer_update, rai, rai);
        ra_timer_update(rai, &rai->timer->tm);
        rtadvd_set_timer(&rai->timer->tm, rai->timer);
        rtadvd_remove_timer(&rai->timer_sol);
        rai->timer_sol = rtadvd_add_timer(ra_timeout_sol, NULL, rai, NULL);
}

static void
rtmsg_input(void)
{
        int n, type, ifindex = 0, plen;
        size_t len;
        union rt_msghdr_buf {
                struct rt_msghdr        rt_msghdr;
                char                    data[2048];
        } buffer;
        char *msg, *next, *lim, **argv;
        char ifname[IF_NAMESIZE];
        struct prefix *prefix;
        struct rainfo *rai;
        const struct in6_addr *addr;
        char addrbuf[INET6_ADDRSTRLEN];
        int prefixchange = 0, argc;

        memset(&buffer, 0, sizeof(buffer));
        n = prog_read(rtsock, &buffer, sizeof(buffer));

        /* We read the buffer first to clear the FD */
        if (do_die)
                return;

        msg = buffer.data;
        if (dflag > 1) {
                logit(LOG_DEBUG, "%s: received a routing message "
                    "(type = %d [%s], len = %d)", __func__, rtmsg_type(msg),
                    rtmsg_typestr(msg), rtmsg_len(msg));
        }
        if (n > rtmsg_len(msg)) {
                /*
                 * This usually won't happen for messages received on 
                 * a routing socket.
                 */
                if (dflag > 1)
                        logit(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, rtmsg_len(msg));
#if 0
                /* adjust length */
                n = rtmsg_len(msg);
#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) |
#ifdef RTM_IFANNOUNCE
                                    RTADV_TYPE2BITMASK(RTM_IFANNOUNCE) |
#endif
                                    RTADV_TYPE2BITMASK(RTM_IFINFO));
                if (len == 0)
                        break;
                type = rtmsg_type(next);
                switch (type) {
                case RTM_ADD:
                case RTM_DELETE:
                        ifindex = get_rtm_ifindex(next);
                        break;
                case RTM_NEWADDR:
                case RTM_DELADDR:
                        ifindex = get_ifam_ifindex(next);
                        break;
#ifdef RTM_IFANNOUNCE
                case RTM_IFANNOUNCE:
                        ifindex = get_ifan_ifindex(next);
                        if (get_ifan_what(next) == IFAN_ARRIVAL) {
                                logit(LOG_DEBUG,
                                       "%s: interface %s arrived",
                                       __func__,
                                       if_indextoname(ifindex, ifname));
                                if (if_argc == 0) {
                                        getconfig(ifname, 0);
                                        continue;
                                }
                                argc = if_argc;
                                argv = if_argv;
                                while (argc--) {
                                        if (strcmp(ifname, *argv++) == 0) {
                                                getconfig(ifname, 0);
                                                break;
                                        }
                                }
                                continue;
                        }
                        break;
#endif
                case RTM_IFINFO:
                        ifindex = get_ifm_ifindex(next);
                        break;
                default:
                        /* should not reach here */
                        if (dflag > 1) {
                                logit(LOG_DEBUG, "%s: unknown rtmsg %d on %s",
                                       __func__, type,
                                       if_indextoname(ifindex, ifname));
                        }
                        continue;
                }

                if ((rai = if_indextorainfo(ifindex)) == NULL) {
                        if (dflag > 1) {
                                logit(LOG_DEBUG,
                                       "%s: route changed on "
                                       "non advertising interface %s (%d)",
                                       __func__,
                                       if_indextoname(ifindex, ifname),
                                       ifindex);
                        }
                        continue;
                }
                oldifflags = rai->ifflags;

                switch (type) {
                case RTM_ADD:
                        /* init ifflags because it may have changed */
                        rai->ifflags = if_getflags(ifindex, rai->ifflags);

                        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) {
                                logit(LOG_INFO, "%s: new interface route's"
                                    "plen %d is invalid for a prefix",
                                    __func__, plen);
                                break;
                        }
                        prefix = find_prefix(rai, addr, plen);
                        if (prefix) {
                                if (prefix->timer) {
                                        /*
                                         * If the prefix has been invalidated,
                                         * make it available again.
                                         */
                                        update_prefix(prefix);
                                        prefixchange = 1;
                                } else if (dflag > 1) {
                                        logit(LOG_DEBUG,
                                            "%s: new prefix(%s/%d) "
                                            "added on %s, "
                                            "but it was already in list",
                                            __func__,
                                            inet_ntop(AF_INET6, addr,
                                            (char *)addrbuf, INET6_ADDRSTRLEN),
                                            plen, rai->ifname);
                                }
                                break;
                        }
                        add_prefix(rai, ifindex, addr, plen);
                        prefixchange = 1;
                        break;
                case RTM_DELETE:
                        /* init ifflags because it may have changed */
                        rai->ifflags = if_getflags(ifindex, rai->ifflags);

                        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) {
                                logit(LOG_INFO,
                                    "%s: deleted interface route's "
                                    "plen %d is invalid for a prefix",
                                    __func__, plen);
                                break;
                        }
                        prefix = find_prefix(rai, addr, plen);
                        if (prefix == NULL) {
                                if (dflag > 1) {
                                        logit(LOG_DEBUG,
                                            "%s: prefix(%s/%d) was "
                                            "deleted on %s, "
                                            "but it was not in list",
                                            __func__,
                                            inet_ntop(AF_INET6, addr,
                                            (char *)addrbuf, INET6_ADDRSTRLEN),
                                            plen, rai->ifname);
                                }
                                break;
                        }
                        invalidate_prefix(prefix);
                        prefixchange = 1;
                        break;
                case RTM_NEWADDR:
                case RTM_DELADDR:
                        /* init ifflags because it may have changed */
                        rai->ifflags = if_getflags(ifindex, rai->ifflags);
                        break;
                case RTM_IFINFO:
                        rai->ifflags = get_ifm_flags(next);
                        break;
#ifdef RTM_IFANNOUNCE
                case RTM_IFANNOUNCE:
                        if (get_ifan_what(next) == IFAN_DEPARTURE) {
                                logit(LOG_DEBUG,
                                       "%s: interface %s departed",
                                       __func__, rai->ifname);
                                TAILQ_REMOVE(&ralist, rai, next);
                                if (rai->leaving)
                                        free_rainfo(rai->leaving);
                                free_rainfo(rai);
                                continue;
                        }
                        break;
#endif
                default:
                        /* should not reach here */
                        if (dflag > 1) {
                                logit(LOG_DEBUG,
                                    "%s: unknown rtmsg %d on %s",
                                    __func__, type,
                                    if_indextoname(ifindex, ifname));
                        }
                        return;
                }

                /* check if an interface flag is changed */
                if ((oldifflags & IFF_UP) != 0 &&       /* UP to DOWN */
                    (rai->ifflags & IFF_UP) == 0) {
                        logit(LOG_INFO,
                            "%s: interface %s becomes down. stop timer.",
                            __func__, rai->ifname);
                        rtadvd_remove_timer(&rai->timer);
                } else if ((oldifflags & IFF_UP) == 0 && /* DOWN to UP */
                         (rai->ifflags & IFF_UP) != 0) {
                        logit(LOG_INFO,
                            "%s: interface %s becomes up. restart timer.",
                            __func__, rai->ifname);

                        rai->initcounter = 0; /* reset the counter */
                        rai->waiting = 0; /* XXX */
                        ra_timer_reset(rai);
                } else if (prefixchange && rai->ifflags & IFF_UP) {
                        /*
                         * An advertised prefix has been added or invalidated.
                         * Will notice the change in a short delay.
                         */
                        rai->initcounter = 0;
                        ra_timer_set_short_delay(rai, rai->timer);
                }
        }

        return;
}

void
rtadvd_input(void)
{
        ssize_t i;
        int *hlimp = NULL;
        struct icmp6_hdr *icp;
        int ifindex = 0;
        struct cmsghdr *cm;
        struct in6_pktinfo *pi = NULL;
        char ntopbuf[INET6_ADDRSTRLEN], ifnamebuf[IFNAMSIZ];
        struct rainfo *rai;

        /*
         * 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 = prog_recvmsg(sock, &rcvmhdr, 0)) == -1)
                return;

        /* We read the buffer first to clear the FD */
        if (do_die)
                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;
                }
                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) {
                logit(LOG_ERR,
                       "%s: failed to get receiving interface",
                       __func__);
                return;
        }
        if (hlimp == NULL) {
                logit(LOG_ERR,
                       "%s: failed to get receiving hop limit",
                       __func__);
                return;
        }

        if ((rai = if_indextorainfo(pi->ipi6_ifindex)) == NULL) {
                if (dflag > 1) {
                        logit(LOG_DEBUG,
                               "%s: received data for non advertising "
                               "interface (%s)",
                               __func__,
                               if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                }
                return;
        }
        /*
         * If we happen to receive data on an interface which is now down,
         * just discard the data.
         */
        if ((rai->ifflags & IFF_UP) == 0) {
                logit(LOG_INFO,
                       "%s: received data on a disabled interface (%s)",
                       __func__,
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        if ((size_t)i < sizeof(struct icmp6_hdr)) {
                logit(LOG_ERR,
                       "%s: packet size(%zd) is too short",
                       __func__, i);
                return;
        }

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

        switch (icp->icmp6_type) {
        case ND_ROUTER_SOLICIT:
                /*
                 * Message verification - RFC-2461 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) {
                        logit(LOG_NOTICE,
                            "%s: RS with invalid hop limit(%d) "
                            "received from %s on %s",
                            __func__, *hlimp,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            INET6_ADDRSTRLEN),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if (icp->icmp6_code) {
                        logit(LOG_NOTICE,
                            "%s: RS with invalid ICMP6 code(%d) "
                            "received from %s on %s",
                            __func__, icp->icmp6_code,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            INET6_ADDRSTRLEN),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if ((size_t)i < sizeof(struct nd_router_solicit)) {
                        logit(LOG_NOTICE,
                            "%s: RS from %s on %s does not have enough "
                            "length (len = %zd)",
                            __func__,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            INET6_ADDRSTRLEN),
                            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-2461 6.1.2
                 * XXX: there's a same dilemma as above... 
                 */
                if (*hlimp != 255) {
                        logit(LOG_NOTICE,
                            "%s: RA with invalid hop limit(%d) "
                            "received from %s on %s",
                            __func__, *hlimp,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            INET6_ADDRSTRLEN),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if (icp->icmp6_code) {
                        logit(LOG_NOTICE,
                            "%s: RA with invalid ICMP6 code(%d) "
                            "received from %s on %s",
                            __func__, icp->icmp6_code,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            INET6_ADDRSTRLEN),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                        return;
                }
                if ((size_t)i < sizeof(struct nd_router_advert)) {
                        logit(LOG_NOTICE,
                            "%s: RA from %s on %s does not have enough "
                            "length (len = %zd)",
                            __func__,
                            inet_ntop(AF_INET6, &rcvfrom.sin6_addr, ntopbuf,
                            INET6_ADDRSTRLEN),
                            if_indextoname(pi->ipi6_ifindex, ifnamebuf), i);
                        return;
                }
                ra_input(i, (struct nd_router_advert *)icp, pi, &rcvfrom);
                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()).
                 */
                logit(LOG_ERR, "%s: invalid icmp type(%d)",
                    __func__, 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], ifnamebuf[IFNAMSIZ];
        union nd_opts ndopts;
        struct rainfo *rai;
        struct soliciter *sol;

        logit(LOG_DEBUG,
               "%s: RS received from %s on %s",
               __func__,
               inet_ntop(AF_INET6, &from->sin6_addr,
                         ntopbuf, INET6_ADDRSTRLEN),
               if_indextoname(pi->ipi6_ifindex, ifnamebuf));

        /* ND option check */
        memset(&ndopts, 0, sizeof(ndopts));
        TAILQ_INIT(&ndopts.nd_opts_list);
        if (nd6_options((struct nd_opt_hdr *)(rs + 1),
                        len - sizeof(struct nd_router_solicit),
                        &ndopts, NDOPT_FLAG_SRCLINKADDR)) {
                logit(LOG_INFO,
                       "%s: ND option check failed for an RS from %s on %s",
                       __func__,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       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-2461 6.1.1)
         */
        if (IN6_IS_ADDR_UNSPECIFIED(&from->sin6_addr) &&
            ndopts.nd_opts_src_lladdr) {
                logit(LOG_INFO,
                       "%s: RS from unspecified src on %s has a link-layer"
                       " address option",
                       __func__,
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                goto done;
        }

        if ((rai = if_indextorainfo(pi->ipi6_ifindex)) == NULL) {
                logit(LOG_INFO,
                       "%s: RS received on non advertising interface(%s)",
                       __func__,
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                goto done;
        }

        if (rai->leaving) {
                logit(LOG_INFO,
                       "%s: RS received on reconfiguring advertising interface(%s)",
                       __func__, rai->ifname);
                goto done;
        }

        rai->rsinput++;         /* increment statistics */

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

        /* record sockaddr waiting for RA, if possible */
        TAILQ_FOREACH(sol, &rai->soliciter, next) {
                if (IN6_ARE_ADDR_EQUAL(&sol->addr.sin6_addr, &from->sin6_addr))
                        break;
        }
        if (sol == NULL) {
                sol = malloc(sizeof(*sol));
                if (sol == NULL) {
                        logit(LOG_ERR, "%s: malloc: %m", __func__);
                } else {
                        sol->addr = *from;
                        /* XXX RFC2553 need clarification on flowinfo */
                        sol->addr.sin6_flowinfo = 0;
                        TAILQ_INSERT_TAIL(&rai->soliciter, sol, next);
                }
        }

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

        ra_timer_set_short_delay(rai, rai->timer_sol);

done:
        free_ndopts(&ndopts);
}

void
ra_timer_set_short_delay(struct rainfo *rai, struct rtadvd_timer *timer)
{
        long delay;     /* must not be greater than 1000000 */
        struct timespec interval, now, min_delay, tm_tmp, *rest;

        /*
         * 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. RFC2461 6.2.6
         */
        delay = arc4random() % MAX_RA_DELAY_TIME;
        interval.tv_sec = 0;
        interval.tv_nsec = delay;
        rest = rtadvd_timer_rest(rai->timer);
        if (timespeccmp(rest, &interval, <)) {
                logit(LOG_DEBUG, "%s: random delay is larger than "
                    "the rest of 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.
         */
        prog_clock_gettime(CLOCK_MONOTONIC, &now);
        timespecsub(&now, &rai->lastsent, &tm_tmp);
        min_delay.tv_sec = MIN_DELAY_BETWEEN_RAS;
        min_delay.tv_nsec = 0;
        if (timespeccmp(&tm_tmp, &min_delay, <)) {
                timespecsub(&min_delay, &tm_tmp, &min_delay);
                timespecadd(&min_delay, &interval, &interval);
        }
        rtadvd_set_timer(&interval, timer);
}

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

        logit(LOG_DEBUG,
               "%s: RA received from %s on %s",
               __func__,
               inet_ntop(AF_INET6, &from->sin6_addr,
                         ntopbuf, INET6_ADDRSTRLEN),
               if_indextoname(pi->ipi6_ifindex, ifnamebuf));

        /* ND option check */
        memset(&ndopts, 0, sizeof(ndopts));
        TAILQ_INIT(&ndopts.nd_opts_list);
        if (nd6_options((struct nd_opt_hdr *)(ra + 1),
            len - sizeof(struct nd_router_advert),
            &ndopts, NDOPT_FLAG_SRCLINKADDR |
            NDOPT_FLAG_PREFIXINFO | NDOPT_FLAG_MTU |
            NDOPT_FLAG_RDNSS | NDOPT_FLAG_DNSSL))
        {
                logit(LOG_INFO,
                    "%s: ND option check failed for an RA from %s on %s",
                    __func__,
                    inet_ntop(AF_INET6, &from->sin6_addr,
                        ntopbuf, INET6_ADDRSTRLEN),
                        if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        /*
         * RA consistency check according to RFC-2461 6.2.7
         */
        if ((rai = if_indextorainfo(pi->ipi6_ifindex)) == 0) {
                logit(LOG_INFO,
                       "%s: received RA from %s on non-advertising"
                       " interface(%s)",
                       __func__,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                goto done;
        }
        if (rai->leaving) {
                logit(LOG_DEBUG,
                       "%s: received RA on re-configuring interface (%s)",
                        __func__, rai->ifname);
                goto done;
        }
        rai->rainput++;         /* increment statistics */

        /* Cur Hop Limit value */
        if (ra->nd_ra_curhoplimit && rai->hoplimit &&
            ra->nd_ra_curhoplimit != rai->hoplimit) {
                logit(LOG_INFO,
                       "%s: CurHopLimit inconsistent on %s:"
                       " %d from %s, %d from us",
                       __func__,
                       rai->ifname,
                       ra->nd_ra_curhoplimit,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       rai->hoplimit);
                inconsistent++;
        }
        /* M flag */
        if ((ra->nd_ra_flags_reserved & ND_RA_FLAG_MANAGED) !=
            rai->managedflg) {
                logit(LOG_INFO,
                       "%s: M flag inconsistent on %s:"
                       " %s from %s, %s from us",
                       __func__,
                       rai->ifname,
                       on_off[!rai->managedflg],
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       on_off[rai->managedflg]);
                inconsistent++;
        }
        /* O flag */
        if ((ra->nd_ra_flags_reserved & ND_RA_FLAG_OTHER) !=
            rai->otherflg) {
                logit(LOG_INFO,
                       "%s: O flag inconsistent on %s:"
                       " %s from %s, %s from us",
                       __func__,
                       rai->ifname,
                       on_off[!rai->otherflg],
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       on_off[rai->otherflg]);
                inconsistent++;
        }
        /* Reachable Time */
        reachabletime = ntohl(ra->nd_ra_reachable);
        if (reachabletime && rai->reachabletime &&
            reachabletime != rai->reachabletime) {
                logit(LOG_INFO,
                       "%s: ReachableTime inconsistent on %s:"
                       " %d from %s, %d from us",
                       __func__,
                       rai->ifname,
                       reachabletime,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       rai->reachabletime);
                inconsistent++;
        }
        /* Retrans Timer */
        retranstimer = ntohl(ra->nd_ra_retransmit);
        if (retranstimer && rai->retranstimer &&
            retranstimer != rai->retranstimer) {
                logit(LOG_INFO,
                       "%s: RetranceTimer inconsistent on %s:"
                       " %d from %s, %d from us",
                       __func__,
                       rai->ifname,
                       retranstimer,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       rai->retranstimer);
                inconsistent++;
        }
        /* Values in the MTU options */
        if (ndopts.nd_opts_mtu) {
                mtu = ntohl(ndopts.nd_opts_mtu->nd_opt_mtu_mtu);
                if (mtu && rai->linkmtu && mtu != rai->linkmtu) {
                        logit(LOG_INFO,
                               "%s: MTU option value inconsistent on %s:"
                               " %d from %s, %d from us",
                               __func__,
                               rai->ifname, mtu,
                               inet_ntop(AF_INET6, &from->sin6_addr,
                                         ntopbuf, INET6_ADDRSTRLEN),
                               rai->linkmtu);
                        inconsistent++;
                }
        }
        /* Preferred and Valid Lifetimes for prefixes */
        if (ndopts.nd_opts_pi)
                if (prefix_check(ndopts.nd_opts_pi, rai, from))
                        inconsistent++;
        TAILQ_FOREACH(optp, &ndopts.nd_opts_list, next)
                if (prefix_check((struct nd_opt_prefix_info *)optp->opt,
                    rai, from))
                        inconsistent++;

        if (inconsistent)
                rai->rainconsistent++;

done:
        free_ndopts(&ndopts);
}

/* 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)
{
        uint32_t preferred_time, valid_time;
        struct prefix *pp;
        int inconsistent = 0;
        char ntopbuf[INET6_ADDRSTRLEN], prefixbuf[INET6_ADDRSTRLEN];
        struct timespec now;
        struct in6_addr prefix;

#if 0                           /* impossible */
        if (pinfo->nd_opt_pi_type != ND_OPT_PREFIX_INFORMATION)
                return 0;
#endif

        memcpy(&prefix, &pinfo->nd_opt_pi_prefix, sizeof(prefix));

        /*
         * log if the adveritsed prefix has link-local scope(sanity check?)
         */
        if (IN6_IS_ADDR_LINKLOCAL(&prefix)) {
                logit(LOG_INFO,
                       "%s: link-local prefix %s/%d is advertised "
                       "from %s on %s",
                       __func__,
                       inet_ntop(AF_INET6, &prefix,
                                 prefixbuf, INET6_ADDRSTRLEN),
                       pinfo->nd_opt_pi_prefix_len,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       rai->ifname);
        }

        if ((pp = find_prefix(rai, &prefix,
                              pinfo->nd_opt_pi_prefix_len)) == NULL) {
                logit(LOG_INFO,
                       "%s: prefix %s/%d from %s on %s is not in our list",
                       __func__,
                       inet_ntop(AF_INET6, &prefix,
                                 prefixbuf, INET6_ADDRSTRLEN),
                       pinfo->nd_opt_pi_prefix_len,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       rai->ifname);
                return 0;
        }

        preferred_time = ntohl(pinfo->nd_opt_pi_preferred_time);
        if (pp->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?
                 */
                prog_clock_gettime(CLOCK_MONOTONIC, &now);
                preferred_time += now.tv_sec;

                if (!pp->timer && rai->clockskew &&
                    llabs((long long)preferred_time - pp->pltimeexpire) > rai->clockskew) {
                        logit(LOG_INFO,
                               "%s: preferred lifetime for %s/%d"
                               " (decr. in real time) inconsistent on %s:"
                               " %d from %s, %ld from us",
                               __func__,
                               inet_ntop(AF_INET6, &prefix,
                                         prefixbuf, INET6_ADDRSTRLEN),
                               pinfo->nd_opt_pi_prefix_len,
                               rai->ifname, preferred_time,
                               inet_ntop(AF_INET6, &from->sin6_addr,
                                         ntopbuf, INET6_ADDRSTRLEN),
                               pp->pltimeexpire);
                        inconsistent++;
                }
        } else if (!pp->timer && preferred_time != pp->preflifetime) {
                logit(LOG_INFO,
                       "%s: preferred lifetime for %s/%d"
                       " inconsistent on %s:"
                       " %d from %s, %d from us",
                       __func__,
                       inet_ntop(AF_INET6, &prefix,
                                 prefixbuf, INET6_ADDRSTRLEN),
                       pinfo->nd_opt_pi_prefix_len,
                       rai->ifname, preferred_time,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       pp->preflifetime);
        }

        valid_time = ntohl(pinfo->nd_opt_pi_valid_time);
        if (pp->vltimeexpire) {
                prog_clock_gettime(CLOCK_MONOTONIC, &now);
                valid_time += now.tv_sec;

                if (!pp->timer && rai->clockskew &&
                    llabs((long long)valid_time - pp->vltimeexpire) > rai->clockskew) {
                        logit(LOG_INFO,
                               "%s: valid lifetime for %s/%d"
                               " (decr. in real time) inconsistent on %s:"
                               " %d from %s, %ld from us",
                               __func__,
                               inet_ntop(AF_INET6, &prefix,
                                         prefixbuf, INET6_ADDRSTRLEN),
                               pinfo->nd_opt_pi_prefix_len,
                               rai->ifname, preferred_time,
                               inet_ntop(AF_INET6, &from->sin6_addr,
                                         ntopbuf, INET6_ADDRSTRLEN),
                               pp->vltimeexpire);
                        inconsistent++;
                }
        } else if (!pp->timer && valid_time != pp->validlifetime) {
                logit(LOG_INFO,
                       "%s: valid lifetime for %s/%d"
                       " inconsistent on %s:"
                       " %d from %s, %d from us",
                       __func__,
                       inet_ntop(AF_INET6, &prefix,
                                 prefixbuf, INET6_ADDRSTRLEN),
                       pinfo->nd_opt_pi_prefix_len,
                       rai->ifname, valid_time,
                       inet_ntop(AF_INET6, &from->sin6_addr,
                                 ntopbuf, INET6_ADDRSTRLEN),
                       pp->validlifetime);
                inconsistent++;
        }

        return inconsistent;
}

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

        TAILQ_FOREACH(pp, &rai->prefix, next) {
                if (plen != pp->prefixlen)
                        continue;
                bytelen = plen / 8;
                bitlen = plen % 8;
                bitmask = 0xff << (8 - bitlen);
                if (memcmp(prefix, &pp->prefix, bytelen))
                        continue;
                if (bitlen == 0 ||
                    ((prefix->s6_addr[bytelen] & bitmask) ==
                     (pp->prefix.s6_addr[bytelen] & bitmask))) {
                        return pp;
                }
        }

        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;
        unsigned char bitmask;

        if (plen0 < plen1)
                return 0;
        bytelen = plen1 / 8;
        bitlen = plen1 % 8;
        bitmask = 0xff << (8 - bitlen);
        if (memcmp(p0, 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_opts *ndopts, uint32_t optflags)
{
        int optlen = 0;

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

                hdr = (struct nd_opt_hdr *)((char *)hdr + optlen);
                if (hdr->nd_opt_len == 0) {
                        logit(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) {
                        logit(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)
                {
                        logit(LOG_INFO, "%s: unknown ND option(type %d)",
                            __func__, hdr->nd_opt_type);
                        continue;
                }

                if ((ndopt_flags[hdr->nd_opt_type] & optflags) == 0) {
                        logit(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.
                 */
                if ((hdr->nd_opt_type == ND_OPT_MTU &&
                    (optlen != sizeof(struct nd_opt_mtu))) ||
                    ((hdr->nd_opt_type == ND_OPT_PREFIX_INFORMATION &&
                    optlen != sizeof(struct nd_opt_prefix_info))) ||
                    (hdr->nd_opt_type == ND_OPT_RDNSS &&
                    ((optlen < (int)sizeof(struct nd_opt_rdnss) ||
                    (optlen - sizeof(struct nd_opt_rdnss)) % 16 != 0))) ||
                    (hdr->nd_opt_type == ND_OPT_DNSSL &&
                    optlen < (int)sizeof(struct nd_opt_dnssl)))
                {
                        logit(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:
                        break;  /* we don't care about these options */
                case ND_OPT_SOURCE_LINKADDR:
                case ND_OPT_MTU:
                        if (ndopts->nd_opt_array[hdr->nd_opt_type]) {
                                logit(LOG_INFO,
                                    "%s: duplicated ND option (type = %d)",
                                    __func__, hdr->nd_opt_type);
                        }
                        ndopts->nd_opt_array[hdr->nd_opt_type] = hdr;
                        break;
                case ND_OPT_PREFIX_INFORMATION:
                {
                        struct nd_optlist *pfxlist;

                        if (ndopts->nd_opts_pi == 0) {
                                ndopts->nd_opts_pi =
                                    (struct nd_opt_prefix_info *)hdr;
                                continue;
                        }
                        if ((pfxlist = malloc(sizeof(*pfxlist))) == NULL) {
                                logit(LOG_ERR, "%s: can't allocate memory",
                                    __func__);
                                goto bad;
                        }
                        pfxlist->opt = hdr;
                        TAILQ_INSERT_TAIL(&ndopts->nd_opts_list, pfxlist, next);

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

        return 0;

  bad:
        free_ndopts(ndopts);
        return -1;
}

static void
free_ndopts(union nd_opts *ndopts)
{
        struct nd_optlist *opt;

        while ((opt = TAILQ_FIRST(&ndopts->nd_opts_list)) != NULL) {
                TAILQ_REMOVE(&ndopts->nd_opts_list, opt, next);
                free(opt);
        }
}

void
sock_open(void)
{
        struct icmp6_filter filt;
        struct ipv6_mreq mreq;
        struct rainfo *ra;
        int on;
        /* XXX: should be max MTU attached to the node */
        static unsigned char answer[1500];

        rcvcmsgbuflen = CMSG_SPACE(sizeof(struct in6_pktinfo)) +
                                CMSG_SPACE(sizeof(int));
        rcvcmsgbuf = malloc(rcvcmsgbuflen);
        if (rcvcmsgbuf == NULL) {
                logit(LOG_ERR, "%s: malloc: %m", __func__);
                exit(EXIT_FAILURE);
        }

        sndcmsgbuflen = CMSG_SPACE(sizeof(struct in6_pktinfo));
        sndcmsgbuf = malloc(sndcmsgbuflen);
        if (sndcmsgbuf == NULL) {
                logit(LOG_ERR, "%s: malloc: %m", __func__);
                exit(EXIT_FAILURE);
        }

        if ((sock = prog_socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) == -1) {
                logit(LOG_ERR, "%s: socket: %m", __func__);
                exit(EXIT_FAILURE);
        }

        /* RFC 4861 Section 4.2 */
        on = 255;
        if (prog_setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &on,
                       sizeof(on)) == -1) {
                logit(LOG_ERR, "%s: IPV6_MULTICAST_HOPS: %m", __func__);
                exit(EXIT_FAILURE);
        }
        on = 255;
        if (prog_setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &on,
                       sizeof(on)) == -1) {
                logit(LOG_ERR, "%s: IPV6_UNICAST_HOPS: %m", __func__);
                exit(EXIT_FAILURE);
        }

        /* specify to tell receiving interface */
        on = 1;
        if (prog_setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on,
                       sizeof(on)) == -1) {
                logit(LOG_ERR, "%s: IPV6_RECVPKTINFO: %m", __func__);
                exit(EXIT_FAILURE);
        }

        on = 1;
        /* specify to tell value of hoplimit field of received IP6 hdr */
        if (prog_setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on,
                       sizeof(on)) == -1) {
                logit(LOG_ERR, "%s: IPV6_RECVHOPLIMIT: %m", __func__);
                exit(EXIT_FAILURE);
        }

        ICMP6_FILTER_SETBLOCKALL(&filt);
        ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
        ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
        if (prog_setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt,
                       sizeof(filt)) == -1) {
                logit(LOG_ERR, "%s: IICMP6_FILTER: %m", __func__);
                exit(EXIT_FAILURE);
        }

        /*
         * join all routers multicast address on each advertising interface.
         */
        if (inet_pton(AF_INET6, ALLROUTERS_LINK,
            mreq.ipv6mr_multiaddr.s6_addr) != 1)
        {
                logit(LOG_ERR, "%s: inet_pton failed(library bug?)",
                    __func__);
                exit(EXIT_FAILURE);
        }
        TAILQ_FOREACH(ra, &ralist, next) {
                mreq.ipv6mr_interface = ra->ifindex;
                if (prog_setsockopt(sock, IPPROTO_IPV6, IPV6_JOIN_GROUP, &mreq,
                               sizeof(mreq)) == -1) {
                        logit(LOG_ERR, "%s: IPV6_JOIN_GROUP(link) on %s: %m",
                               __func__, ra->ifname);
                        continue;
                }
        }

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

/* open a routing socket to watch the routing table */
static void
rtsock_open(void)
{
#ifdef RO_MSGFILTER
        unsigned char msgfilter[] = {
                RTM_ADD, RTM_DELETE,
                RTM_NEWADDR, RTM_DELADDR,
#ifdef RTM_IFANNOUNCE
                RTM_IFANNOUNCE,
#endif
                RTM_IFINFO,
        };
#endif

        if ((rtsock = prog_socket(PF_ROUTE, SOCK_RAW, 0)) == -1) {
                logit(LOG_ERR, "%s: socket: %m", __func__);
                exit(EXIT_FAILURE);
        }
#ifdef RO_MSGFILTER
        if (prog_setsockopt(rtsock, PF_ROUTE, RO_MSGFILTER,
            &msgfilter, sizeof(msgfilter)) == -1)
                logit(LOG_ERR, "%s: RO_MSGFILTER: %m", __func__);
#endif
}

struct rainfo *
if_indextorainfo(unsigned int idx)
{
        struct rainfo *rai;

        TAILQ_FOREACH(rai, &ralist, next) {
                if (rai->ifindex == idx)
                        return rai;
        }

        return NULL;            /* search failed */
}

struct rainfo *
ra_output(struct rainfo *rai, bool solicited)
{
        int i;
        struct cmsghdr *cm;
        struct in6_pktinfo *pi;
        struct soliciter *sol;

        if ((rai->ifflags & IFF_UP) == 0) {
                logit(LOG_DEBUG, "%s: %s is not up, skip sending RA",
                       __func__, rai->ifname);
                return NULL;
        }

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

        sndmhdr.msg_name = (void *)&sin6_linklocal_allnodes;
        sndmhdr.msg_iov[0].iov_base = (void *)rai->ra_data;
        sndmhdr.msg_iov[0].iov_len = rai->ra_datalen;

        /* specify the outgoing interface */
        cm = CMSG_FIRSTHDR(&sndmhdr);
        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 = rai->ifindex;

        logit(LOG_DEBUG,
               "%s: send RA on %s, # of waitings = %d",
               __func__, rai->ifname, rai->waiting); 

        if (solicited) {
                /* unicast solicited RA's as per RFC 7772 */
                while ((sol = TAILQ_FIRST(&rai->soliciter)) != NULL) {
                        sndmhdr.msg_name = (void *)&sol->addr;
                        i = prog_sendmsg(sock, &sndmhdr, 0);
                        if (i < 0 || (size_t)i != rai->ra_datalen)  {
                                if (i < 0) {
                                        logit(LOG_ERR,
                                            "%s: unicast sendmsg on %s: %m",
                                            __func__, rai->ifname);
                                }
                        }
                        TAILQ_REMOVE(&rai->soliciter, sol, next);
                        free(sol);
                }

                /* reset waiting counter */
                rai->waiting = 0;

                /* disable timer */
                rai->timer_sol->enabled = false;

                return rai;
        }

        i = prog_sendmsg(sock, &sndmhdr, 0);
        if (i < 0 || (size_t)i != rai->ra_datalen)  {
                if (i < 0) {
                        logit(LOG_ERR, "%s: sendmsg on %s: %m",
                               __func__, rai->ifname);
                }
        }

        if (rai->leaving_adv > 0) {
                if (--(rai->leaving_adv) == 0) {
                        /* leaving for ourself means we're shutting down */
                        if (rai->leaving_for == rai) {
                                TAILQ_REMOVE(&ralist, rai, next);
                                free_rainfo(rai);
                                return NULL;
                        }
                        logit(LOG_DEBUG,
                               "%s: expired RA,"
                               " new config active for interface (%s)",
                               __func__, rai->ifname);
                        ra_timer_reset(rai->leaving_for);
                        rai->leaving_for->leaving = NULL;
                        free_rainfo(rai);
                        return NULL;
                }
        }

        /* update counter */
        if (rai->initcounter < MAX_INITIAL_RTR_ADVERTISEMENTS)
                rai->initcounter++;
        rai->raoutput++;

        /* update timestamp */
        prog_clock_gettime(CLOCK_MONOTONIC, &rai->lastsent);
        return rai;
}

/* process unsolicited RA timer */
struct rtadvd_timer *
ra_timeout(void *data)
{
        struct rainfo *rai = (struct rainfo *)data;

        logit(LOG_DEBUG,
               "%s: unsolicited RA timer on %s is expired",
               __func__, rai->ifname);

        if (ra_output(rai, false))
                return rai->timer;
        return NULL;
}

/* process solicited RA timer */
struct rtadvd_timer *
ra_timeout_sol(void *data)
{
        struct rainfo *rai = (struct rainfo *)data;

        logit(LOG_DEBUG,
               "%s: solicited RA timer on %s is expired",
               __func__, rai->ifname);

        if (ra_output(rai, true))
                return rai->timer_sol;
        return NULL;
}

/* update RA timer */
void
ra_timer_update(void *data, struct timespec *tm)
{
        struct rainfo *rai = (struct rainfo *)data;
        long interval;

        /*
         * 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 (RFC2461 6.2.4).
         */
        interval = rai->mininterval;
        if (rai->mininterval != rai->maxinterval)
                interval += arc4random() % (rai->maxinterval-rai->mininterval);

        /*
         * 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-2461 6.2.4)
         */
        if (rai->initcounter < MAX_INITIAL_RTR_ADVERTISEMENTS &&
            interval > MAX_INITIAL_RTR_ADVERT_INTERVAL)
                interval = MAX_INITIAL_RTR_ADVERT_INTERVAL;

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

        logit(LOG_DEBUG,
               "%s: RA timer on %s is set to %jd:%jd",
               __func__, rai->ifname,
               (intmax_t)tm->tv_sec, (intmax_t)tm->tv_nsec);
}

void
logit(int level, const char *fmt, ...)
{
        va_list ap;
        char *buf;

        va_start(ap, fmt);
        if (!Dflag && after_daemon) {
                vsyslog(level, fmt, ap);
                goto out;
        }
        if (level >= LOG_INFO && !dflag) {
                goto out;
        }

        vwarnx(expandm(fmt, "", &buf), ap);
        free(buf);
out:
        va_end(ap);
}