/*      $NetBSD: config.c,v 1.47 2021/11/27 22:30:26 rillig Exp $       */
/*      $KAME: config.c,v 1.93 2005/10/17 14:40:02 suz Exp $    */

/*
 * Copyright (C) 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/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/route.h>
#include <net/if_dl.h>
#ifdef __FreeBSD__
#include <net/if_var.h>
#endif

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>

#include <arpa/inet.h>

#include <stdio.h>
#include <syslog.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <search.h>
#include <unistd.h>
#include <ifaddrs.h>
#include <inttypes.h>

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

#ifndef __arraycount
#define __arraycount(__x)       (sizeof(__x) / sizeof(__x[0]))
#endif

static time_t prefix_timo = (60 * 120); /* 2 hours.
                                         * XXX: should be configurable. */
static struct rtadvd_timer *prefix_timeout(void *);
static void makeentry(char *, size_t, int, const char *);
static int getinet6sysctl(int);

static size_t
encode_domain(char *dst, const char *src)
{
        ssize_t len;
        char *odst, *p;

        odst = dst;
        while (src && (len = strlen(src)) != 0) {
                p = strchr(src, '.');
                *dst++ = len = MIN(63, p == NULL ? len : p - src);
                memcpy(dst, src, len);
                dst += len;
                if (p == NULL)
                        break;
                src = p + 1;
        }
        *dst++ = '\0';

        return dst - odst;
}

void
free_rainfo(struct rainfo *rai)
{
        struct soliciter *sol;
        struct prefix *pfx;
        struct rtinfo *rti;
        struct rdnss *rdnss;
        struct rdnss_addr *rdnsa;
        struct dnssl *dnssl;
        struct dnssl_domain *dnsd;

        rtadvd_remove_timer(&rai->timer);
        rtadvd_remove_timer(&rai->timer_sol);

        while ((sol = TAILQ_FIRST(&rai->soliciter))) {
                TAILQ_REMOVE(&rai->soliciter, sol, next);
                free(sol);
        }

        while ((pfx = TAILQ_FIRST(&rai->prefix))) {
                TAILQ_REMOVE(&rai->prefix, pfx, next);
                free(pfx);
        }

        while ((rti = TAILQ_FIRST(&rai->route))) {
                TAILQ_REMOVE(&rai->route, rti, next);
                free(rti);
        }

        while ((rdnss = TAILQ_FIRST(&rai->rdnss))) {
                TAILQ_REMOVE(&rai->rdnss, rdnss, next);
                while ((rdnsa = TAILQ_FIRST(&rdnss->list))) {
                        TAILQ_REMOVE(&rdnss->list, rdnsa, next);
                        free(rdnsa);
                }
                free(rdnss);
        }

        while ((dnssl = TAILQ_FIRST(&rai->dnssl))) {
                TAILQ_REMOVE(&rai->dnssl, dnssl, next);
                while ((dnsd = TAILQ_FIRST(&dnssl->list))) {
                        TAILQ_REMOVE(&dnssl->list, dnsd, next);
                        free(dnsd);
                }
                free(dnssl);
        }

        free(rai->sdl);
        free(rai->ra_data);
        free(rai);
}

void
getconfig(const char *intface, int exithard)
{
        int stat, c, i;
        char tbuf[BUFSIZ];
        struct rainfo *tmp, *rai;
        int32_t val;
        int64_t val64;
        char buf[BUFSIZ];
        char *bp = buf;
        char *addr, *flagstr, *ap;
        static int forwarding = -1;
        char entbuf[256], abuf[256];
        struct rdnss *rdnss;
        struct dnssl *dnssl;

#define MUSTHAVE(var, cap)                                              \
    do {                                                                \
        int64_t t;                                                      \
        if ((t = agetnum(cap)) < 0) {                                   \
                logit(LOG_ERR, "%s: need %s for interface %s",          \
                    __func__, cap, intface);                            \
                goto errexit;                                           \
        }                                                               \
        var = t;                                                        \
     } while (0)

#define MAYHAVE(var, cap, def)                                          \
     do {                                                               \
        if ((var = agetnum(cap)) < 0)                                   \
                var = def;                                              \
     } while (0)

#define ELM_MALLOC(p)                                                   \
        do {                                                            \
                p = calloc(1, sizeof(*p));                              \
                if (p == NULL) {                                        \
                        logit(LOG_ERR, "%s: calloc failed: %m", \
                            __func__);                                  \
                        goto errexit;                                   \
                }                                                       \
        } while(/*CONSTCOND*/0)

        if (if_nametoindex(intface) == 0) {
                logit(LOG_INFO, "%s: interface %s not found, ignoring",
                       __func__, intface);
                return;
        }

        logit(LOG_DEBUG, "%s: loading configuration for interface %s",
               __func__, intface);

        if ((stat = agetent(tbuf, intface)) <= 0) {
                memset(tbuf, 0, sizeof(tbuf));
                logit(LOG_INFO,
                       "%s: %s isn't defined in the configuration file"
                       " or the configuration file doesn't exist."
                       " Treat it as default",
                        __func__, intface);
        }

        ELM_MALLOC(tmp);
        TAILQ_INIT(&tmp->soliciter);
        TAILQ_INIT(&tmp->prefix);
        TAILQ_INIT(&tmp->route);
        TAILQ_INIT(&tmp->rdnss);
        TAILQ_INIT(&tmp->dnssl);

        /* check if we are allowed to forward packets (if not determined) */
        if (forwarding < 0) {
                if ((forwarding = getinet6sysctl(IPV6CTL_FORWARDING)) < 0)
                        exit(EXIT_FAILURE);
        }

        /* get interface information */
        if (agetflag("nolladdr"))
                tmp->advlinkopt = 0;
        else
                tmp->advlinkopt = 1;
        if (tmp->advlinkopt) {
                if ((tmp->sdl = if_nametosdl(intface)) == NULL) {
                        logit(LOG_ERR,
                               "%s: can't get information of %s",
                               __func__, intface);
                        goto errexit;
                }
                tmp->ifindex = tmp->sdl->sdl_index;
        } else {
                tmp->ifindex = if_nametoindex(intface);
                if (tmp->ifindex == 0) {
                        logit(LOG_ERR,
                               "%s: can't get information of %s",
                               __func__, intface);
                        goto errexit;
                }
        }
        tmp->ifflags = if_getflags(tmp->ifindex, 0);
        strlcpy(tmp->ifname, intface, sizeof(tmp->ifname));
        if ((tmp->phymtu = if_getmtu(intface)) == 0) {
                tmp->phymtu = IPV6_MMTU;
                logit(LOG_WARNING,
                       "%s: can't get interface mtu of %s. Treat as %d",
                       __func__, intface, IPV6_MMTU);
        }

        /*
         * set router configuration variables.
         */
        MAYHAVE(val, "maxinterval", DEF_MAXRTRADVINTERVAL);
        if (val < MIN_MAXINTERVAL || val > MAX_MAXINTERVAL) {
                logit(LOG_ERR,
                       "%s: maxinterval (%d) on %s is invalid "
                       "(must be between %u and %u)", __func__, val,
                       intface, MIN_MAXINTERVAL, MAX_MAXINTERVAL);
                goto errexit;
        }
        tmp->maxinterval = val;
        MAYHAVE(val, "mininterval", tmp->maxinterval/3);
        if (val < MIN_MININTERVAL || val > (tmp->maxinterval * 3) / 4) {
                logit(LOG_ERR,
                       "%s: mininterval (%d) on %s is invalid "
                       "(must be between %u and %d)",
                       __func__, val, intface, MIN_MININTERVAL,
                       (tmp->maxinterval * 3) / 4);
                goto errexit;
        }
        tmp->mininterval = val;

        MAYHAVE(val, "chlim", DEF_ADVCURHOPLIMIT);
        tmp->hoplimit = val & 0xff;

        if ((flagstr = agetstr("raflags", &bp))) {
                val = 0;
                if (strchr(flagstr, 'm'))
                        val |= ND_RA_FLAG_MANAGED;
                if (strchr(flagstr, 'o'))
                        val |= ND_RA_FLAG_OTHER;
                if (strchr(flagstr, 'h'))
                        val |= ND_RA_FLAG_RTPREF_HIGH;
                if (strchr(flagstr, 'l')) {
                        if ((val & ND_RA_FLAG_RTPREF_HIGH)) {
                                logit(LOG_ERR, "%s: the \'h\' and \'l\'"
                                    " router flags are exclusive", __func__);
                                goto errexit;
                        }
                        val |= ND_RA_FLAG_RTPREF_LOW;
                }
        } else {
                MAYHAVE(val, "raflags", 0);
        }
        tmp->managedflg = val & ND_RA_FLAG_MANAGED;
        tmp->otherflg = val & ND_RA_FLAG_OTHER;
#ifndef ND_RA_FLAG_RTPREF_MASK
#define ND_RA_FLAG_RTPREF_MASK  0x18 /* 00011000 */
#define ND_RA_FLAG_RTPREF_RSV   0x10 /* 00010000 */
#endif
        tmp->rtpref = val & ND_RA_FLAG_RTPREF_MASK;
        if (tmp->rtpref == ND_RA_FLAG_RTPREF_RSV) {
                logit(LOG_ERR, "%s: invalid router preference (%02x) on %s",
                       __func__, tmp->rtpref, intface);
                goto errexit;
        }

        MAYHAVE(val, "rltime", DEF_ADVROUTERLIFETIME);
        if (val && (val < tmp->maxinterval || val > MAXROUTERLIFETIME)) {
                logit(LOG_ERR, "%s: router lifetime (%d) on %s is invalid "
                       "(must be 0 or between %d and %d)",
                       __func__, val, intface,
                       tmp->maxinterval, MAXROUTERLIFETIME);
                goto errexit;
        }
        /*
         * Basically, hosts MUST NOT send Router Advertisement messages at any
         * time (RFC 2461, 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)
         */
        if (val && forwarding == 0) {
                logit(LOG_ERR,
                       "%s: non zero router lifetime is specified for %s, "
                       "which must not be allowed for hosts.  you must "
                       "change router lifetime or enable IPv6 forwarding.",
                       __func__, intface);
                goto errexit;
        }
        tmp->lifetime = val & 0xffff;

        MAYHAVE(val, "rtime", DEF_ADVREACHABLETIME);
        if (val < 0 || val > MAXREACHABLETIME) {
                logit(LOG_ERR,
                       "%s: reachable time (%d) on %s is invalid "
                       "(must be no greater than %d)",
                       __func__, val, intface, MAXREACHABLETIME);
                goto errexit;
        }
        tmp->reachabletime = (uint32_t)val;

        MAYHAVE(val64, "retrans", DEF_ADVRETRANSTIMER);
        if (val64 < 0 || val64 > 0xffffffff) {
                logit(LOG_ERR, "%s: retrans time (%lld) on %s out of range",
                       __func__, (long long)val64, intface);
                goto errexit;
        }
        tmp->retranstimer = (uint32_t)val64;

        if (agetnum("hapref") != -1 || agetnum("hatime") != -1) {
                logit(LOG_ERR,
                       "%s: mobile-ip6 configuration not supported",
                       __func__);
                goto errexit;
        }
        /* prefix information */

        /*
         * This is an implementation specific parameter to consider
         * link propagation delays and poorly synchronized clocks when
         * checking consistency of advertised lifetimes.
         */
        MAYHAVE(val, "clockskew", 0);
        tmp->clockskew = val;

        tmp->pfxs = 0;
        for (i = -1; i < MAXPREFIX; i++) {
                struct prefix *pfx;

                makeentry(entbuf, sizeof(entbuf), i, "addr");
                addr = (char *)agetstr(entbuf, &bp);
                if (addr == NULL)
                        continue;

                /* allocate memory to store prefix information */
                if ((pfx = calloc(1, sizeof(*pfx))) == NULL) {
                        logit(LOG_ERR,
                               "%s: can't allocate memory: %m",
                               __func__);
                        goto errexit;
                }

                TAILQ_INSERT_TAIL(&tmp->prefix, pfx, next);
                tmp->pfxs++;
                pfx->rainfo = tmp;

                pfx->origin = PREFIX_FROM_CONFIG;

                if (inet_pton(AF_INET6, addr, &pfx->prefix) != 1) {
                        logit(LOG_ERR,
                               "%s: inet_pton failed for %s",
                               __func__, addr);
                        goto errexit;
                }
                if (IN6_IS_ADDR_MULTICAST(&pfx->prefix)) {
                        logit(LOG_ERR,
                               "%s: multicast prefix (%s) must "
                               "not be advertised on %s",
                               __func__, addr, intface);
                        goto errexit;
                }
                if (IN6_IS_ADDR_LINKLOCAL(&pfx->prefix))
                        logit(LOG_NOTICE,
                               "%s: link-local prefix (%s) will be"
                               " advertised on %s",
                               __func__, addr, intface);

                makeentry(entbuf, sizeof(entbuf), i, "prefixlen");
                MAYHAVE(val, entbuf, 64);
                if (val < 0 || val > 128) {
                        logit(LOG_ERR, "%s: prefixlen (%d) for %s "
                               "on %s out of range",
                               __func__, val, addr, intface);
                        goto errexit;
                }
                pfx->prefixlen = (int)val;

                makeentry(entbuf, sizeof(entbuf), i, "pinfoflags");
                if ((flagstr = (char *)agetstr(entbuf, &bp))) {
                        val = 0;
                        if (strchr(flagstr, 'l'))
                                val |= ND_OPT_PI_FLAG_ONLINK;
                        if (strchr(flagstr, 'a'))
                                val |= ND_OPT_PI_FLAG_AUTO;
                } else {
                        MAYHAVE(val, entbuf,
                            (ND_OPT_PI_FLAG_ONLINK|ND_OPT_PI_FLAG_AUTO));
                }
                pfx->onlinkflg = val & ND_OPT_PI_FLAG_ONLINK;
                pfx->autoconfflg = val & ND_OPT_PI_FLAG_AUTO;

                makeentry(entbuf, sizeof(entbuf), i, "vltime");
                MAYHAVE(val64, entbuf, DEF_ADVVALIDLIFETIME);
                if (val64 < 0 || val64 > 0xffffffff) {
                        logit(LOG_ERR, "%s: vltime (%lld) for "
                            "%s/%d on %s is out of range",
                            __func__, (long long)val64,
                            addr, pfx->prefixlen, intface);
                        goto errexit;
                }
                pfx->validlifetime = (uint32_t)val64;

                makeentry(entbuf, sizeof(entbuf), i, "vltimedecr");
                if (agetflag(entbuf)) {
                        struct timespec now;
                        prog_clock_gettime(CLOCK_MONOTONIC, &now);
                        pfx->vltimeexpire =
                                now.tv_sec + pfx->validlifetime;
                }

                makeentry(entbuf, sizeof(entbuf), i, "pltime");
                MAYHAVE(val64, entbuf, DEF_ADVPREFERREDLIFETIME);
                if (val64 < 0 || val64 > 0xffffffff) {
                        logit(LOG_ERR,
                            "%s: pltime (%lld) for %s/%d on %s "
                            "is out of range",
                            __func__, (long long)val64,
                            addr, pfx->prefixlen, intface);
                        goto errexit;
                }
                pfx->preflifetime = (uint32_t)val64;

                makeentry(entbuf, sizeof(entbuf), i, "pltimedecr");
                if (agetflag(entbuf)) {
                        struct timespec now;
                        prog_clock_gettime(CLOCK_MONOTONIC, &now);
                        pfx->pltimeexpire =
                                now.tv_sec + pfx->preflifetime;
                }
        }
        if (TAILQ_FIRST(&tmp->prefix) == NULL && !agetflag("noifprefix"))
                get_prefix(tmp);

        MAYHAVE(val64, "mtu", 0);
        if (val64 < 0 || val64 > 0xffffffff) {
                logit(LOG_ERR,
                       "%s: mtu (%" PRIi64 ") on %s out of range",
                       __func__, val64, intface);
                goto errexit;
        }
        tmp->linkmtu = (uint32_t)val64;
        if (tmp->linkmtu == 0) {
                char *mtustr;

                if ((mtustr = (char *)agetstr("mtu", &bp)) &&
                    strcmp(mtustr, "auto") == 0)
                        tmp->linkmtu = tmp->phymtu;
        }
        else if (tmp->linkmtu < IPV6_MMTU || tmp->linkmtu > tmp->phymtu) {
                logit(LOG_ERR,
                       "%s: advertised link mtu (%d) on %s is invalid (must "
                       "be between least MTU (%d) and physical link MTU (%d)",
                       __func__, tmp->linkmtu, intface,
                       IPV6_MMTU, tmp->phymtu);
                goto errexit;
        }

        /* route information */
        for (i = -1; i < MAXROUTE; i++) {
                struct rtinfo *rti;
                char oentbuf[256];

                makeentry(entbuf, sizeof(entbuf), i, "rtprefix");
                addr = (char *)agetstr(entbuf, &bp);
                if (addr == NULL) {
                        makeentry(oentbuf, sizeof(oentbuf), i, "rtrprefix");
                        addr = (char *)agetstr(oentbuf, &bp);
                        if (addr) {
                                fprintf(stderr, "%s was obsoleted.  Use %s.\n",
                                        oentbuf, entbuf);
                        }
                }
                if (addr == NULL)
                        continue;

                ELM_MALLOC(rti);
                memset(rti, 0, sizeof(*rti));

                /* link into chain */
                TAILQ_INSERT_TAIL(&tmp->route, rti, next);

                if (inet_pton(AF_INET6, addr, &rti->prefix) != 1) {
                        logit(LOG_ERR, "%s: inet_pton failed for %s",
                               __func__, addr);
                        goto errexit;
                }
#if 0
                /*
                 * XXX: currently there's no restriction in route information
                 * prefix according to
                 * draft-ietf-ipngwg-router-selection-00.txt.
                 * However, I think the similar restriction be necessary.
                 */
                MAYHAVE(val64, entbuf, DEF_ADVVALIDLIFETIME);
                if (IN6_IS_ADDR_MULTICAST(&rti->prefix)) {
                        logit(LOG_ERR,
                               "%s: multicast route (%s) must "
                               "not be advertised on %s",
                               __func__, addr, intface);
                        goto errexit;
                }
                if (IN6_IS_ADDR_LINKLOCAL(&rti->prefix)) {
                        logit(LOG_NOTICE,
                               "%s: link-local route (%s) will "
                               "be advertised on %s",
                               __func__, addr, intface);
                        goto errexit;
                }
#endif

                makeentry(entbuf, sizeof(entbuf), i, "rtplen");
                /* XXX: 256 is a magic number for compatibility check. */
                MAYHAVE(val, entbuf, 256);
                if (val == 256) {
                        makeentry(oentbuf, sizeof(oentbuf), i, "rtrplen");
                        MAYHAVE(val, oentbuf, 256);
                        if (val != 256) {
                                fprintf(stderr, "%s was obsoleted.  Use %s.\n",
                                        oentbuf, entbuf);
                        } else
                                val = 64;
                }
                if (val < 0 || val > 128) {
                        logit(LOG_ERR, "%s: prefixlen (%d) for %s on %s "
                               "out of range",
                               __func__, val, addr, intface);
                        goto errexit;
                }
                rti->prefixlen = (int)val;

                makeentry(entbuf, sizeof(entbuf), i, "rtflags");
                if ((flagstr = (char *)agetstr(entbuf, &bp))) {
                        val = 0;
                        if (strchr(flagstr, 'h'))
                                val |= ND_RA_FLAG_RTPREF_HIGH;
                        if (strchr(flagstr, 'l')) {
                                if ((val & ND_RA_FLAG_RTPREF_HIGH)) {
                                        logit(LOG_ERR,
                                            "%s: the \'h\' and \'l\' route"
                                            " preferences are exclusive",
                                            __func__);
                                        goto errexit;
                                }
                                val |= ND_RA_FLAG_RTPREF_LOW;
                        }
                } else
                        MAYHAVE(val, entbuf, 256); /* XXX */
                if (val == 256) {
                        makeentry(oentbuf, sizeof(oentbuf), i, "rtrflags");
                        MAYHAVE(val, oentbuf, 256);
                        if (val != 256) {
                                fprintf(stderr, "%s was obsoleted.  Use %s.\n",
                                        oentbuf, entbuf);
                        } else
                                val = 0;
                }
                rti->rtpref = val & ND_RA_FLAG_RTPREF_MASK;
                if (rti->rtpref == ND_RA_FLAG_RTPREF_RSV) {
                        logit(LOG_ERR, "%s: invalid route preference (%02x) "
                               "for %s/%d on %s",
                               __func__, rti->rtpref, addr,
                               rti->prefixlen, intface);
                        goto errexit;
                }

                /*
                 * Since the spec does not a default value, we should make
                 * this entry mandatory.  However, FreeBSD 4.4 has shipped
                 * with this field being optional, we use the router lifetime
                 * as an ad-hoc default value with a warning message.
                 */
                makeentry(entbuf, sizeof(entbuf), i, "rtltime");
                MAYHAVE(val64, entbuf, -1);
                if (val64 == -1) {
                        makeentry(oentbuf, sizeof(oentbuf), i, "rtrltime");
                        MAYHAVE(val64, oentbuf, -1);
                        if (val64 != -1) {
                                fprintf(stderr, "%s was obsoleted.  Use %s.\n",
                                        oentbuf, entbuf);
                        } else {
                                fprintf(stderr, "%s should be specified "
                                        "for interface %s.\n",
                                        entbuf, intface);
                                val64 = tmp->lifetime;
                        }
                }
                if (val64 < 0 || val64 > 0xffffffff) {
                        logit(LOG_ERR, "%s: route lifetime (%lld) for "
                            "%s/%d on %s out of range", __func__,
                            (long long)val64, addr, rti->prefixlen, intface);
                        goto errexit;
                }
                rti->ltime = (uint32_t)val64;
        }

        /* RDNSS */
        for (i = -1; i < MAXRDNSS; i++) {
                struct rdnss_addr *rdnsa;

                makeentry(entbuf, sizeof(entbuf), i, "rdnss");
                addr = (char *)agetstr(entbuf, &bp);
                if (addr == NULL)
                        continue;

                ELM_MALLOC(rdnss);
                TAILQ_INSERT_TAIL(&tmp->rdnss, rdnss, next);
                TAILQ_INIT(&rdnss->list);

                for (ap = addr; ap - addr < (ssize_t)strlen(addr); ap += c+1) {
                        c = strcspn(ap, ",");
                        strncpy(abuf, ap, c);
                        abuf[c] = '\0';
                        ELM_MALLOC(rdnsa);
                        TAILQ_INSERT_TAIL(&rdnss->list, rdnsa, next);
                        if (inet_pton(AF_INET6, abuf, &rdnsa->addr) != 1) {
                                logit(LOG_ERR, "%s: inet_pton failed for %s",
                                   __func__, addr);
                                goto errexit;
                        }
                }

                makeentry(entbuf, sizeof(entbuf), i, "rdnssltime");
                MAYHAVE(val64, entbuf, tmp->maxinterval * 3 / 2);
                if (val64 < 0 || val64 > 0xffffffff) {
                        logit(LOG_ERR, "%s: %s (%lld) on %s is invalid",
                             __func__, entbuf, (long long)val64, intface);
                        goto errexit;
                }
                rdnss->lifetime = (uint32_t)val64;

        }

        /* DNSSL */
        TAILQ_INIT(&tmp->dnssl);
        for (i = -1; i < MAXDNSSL; i++) {
                struct dnssl_domain *dnsd;

                makeentry(entbuf, sizeof(entbuf), i, "dnssl");
                addr = (char *)agetstr(entbuf, &bp);
                if (addr == NULL)
                        continue;

                ELM_MALLOC(dnssl);
                TAILQ_INSERT_TAIL(&tmp->dnssl, dnssl, next);
                TAILQ_INIT(&dnssl->list);

                for (ap = addr; ap - addr < (ssize_t)strlen(addr); ap += c+1) {
                        c = strcspn(ap, ",");
                        strncpy(abuf, ap, c);
                        abuf[c] = '\0';
                        ELM_MALLOC(dnsd);
                        TAILQ_INSERT_TAIL(&dnssl->list, dnsd, next);
                        dnsd->len = encode_domain(dnsd->domain, abuf);
                }

                makeentry(entbuf, sizeof(entbuf), i, "dnsslltime");
                MAYHAVE(val64, entbuf, tmp->maxinterval * 3 / 2);
                if (val64 < 0 || val64 > 0xffffffff) {
                        logit(LOG_ERR, "%s: %s (%lld) on %s is invalid",
                             __func__, entbuf, (long long)val64, intface);
                        goto errexit;
                }
                dnssl->lifetime = (uint32_t)val64;

        }

        TAILQ_FOREACH(rai, &ralist, next) {
                if (rai->ifindex == tmp->ifindex) {
                        TAILQ_REMOVE(&ralist, rai, next);
                        if (Cflag) {
                                free_rainfo(rai);
                                rai = NULL;
                                break;
                        }
                        /* If we already have a leaving RA use that
                         * as this config hasn't been advertised */
                        if (rai->leaving) {
                                tmp->leaving = rai->leaving;
                                free_rainfo(rai);
                                rai = tmp->leaving;
                                rai->leaving_for = tmp;
                                break;
                        }
                        rai->lifetime = 0;
                        TAILQ_FOREACH(rdnss, &rai->rdnss, next)
                                rdnss->lifetime = 0;
                        TAILQ_FOREACH(dnssl, &rai->dnssl, next)
                                dnssl->lifetime = 0;
                        rai->leaving_for = tmp;
                        tmp->leaving = 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;
                        if (rai->timer == NULL)
                                rai->timer = rtadvd_add_timer(ra_timeout,
                                                              ra_timer_update,
                                                              rai, rai);
                        ra_timer_update((void *)rai, &rai->timer->tm);
                        rtadvd_set_timer(&rai->timer->tm, rai->timer);
                        break;
                }
        }

        /* okey */
        TAILQ_INSERT_TAIL(&ralist, tmp, next);

        /* construct the sending packet */
        make_packet(tmp);

        /* set timer */
        if (rai)
                return;
        tmp->timer = rtadvd_add_timer(ra_timeout, ra_timer_update,
                                      tmp, tmp);
        ra_timer_set_short_delay(tmp, tmp->timer);
        tmp->timer_sol = rtadvd_add_timer(ra_timeout_sol, NULL, tmp, NULL);

        return;

errexit:
        if (exithard)
                exit(EXIT_FAILURE);
        free_rainfo(tmp);
}

void
get_prefix(struct rainfo *rai)
{
        struct ifaddrs *ifap, *ifa;
        struct prefix *pp;
        struct in6_addr *a;
        unsigned char *p, *ep, *m, *lim;
        char ntopbuf[INET6_ADDRSTRLEN];

        if (getifaddrs(&ifap) < 0) {
                logit(LOG_ERR,
                       "%s: can't get interface addresses",
                       __func__);
                exit(EXIT_FAILURE);
        }

        for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
                int plen;

                if (strcmp(ifa->ifa_name, rai->ifname) != 0)
                        continue;
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                a = &((struct sockaddr_in6 *)ifa->ifa_addr)->sin6_addr;
                if (IN6_IS_ADDR_LINKLOCAL(a))
                        continue;
                /* get prefix length */
                m = (unsigned char *)&((struct sockaddr_in6 *)ifa->ifa_netmask)->sin6_addr;
                lim = (unsigned char *)(ifa->ifa_netmask) + ifa->ifa_netmask->sa_len;
                plen = prefixlen(m, lim);
                if (plen <= 0 || plen > 128) {
                        logit(LOG_ERR, "%s: failed to get prefixlen "
                               "or prefix is invalid",
                               __func__);
                        exit(EXIT_FAILURE);
                }
                if (plen == 128)        /* XXX */
                        continue;
                if (find_prefix(rai, a, plen)) {
                        /* ignore a duplicated prefix. */
                        continue;
                }

                /* allocate memory to store prefix info. */
                if ((pp = calloc(1, sizeof(*pp))) == NULL) {
                        logit(LOG_ERR,
                               "%s: can't get allocate buffer for prefix",
                               __func__);
                        exit(EXIT_FAILURE);
                }

                /* set prefix, sweep bits outside of prefixlen */
                pp->prefixlen = plen;
                memcpy(&pp->prefix, a, sizeof(*a));
                if (1)
                {
                        p = (unsigned char *)&pp->prefix;
                        ep = (unsigned char *)(&pp->prefix + 1);
                        while (m < lim && p < ep)
                                *p++ &= *m++;
                        while (p < ep)
                                *p++ = 0x00;
                }
                if (!inet_ntop(AF_INET6, &pp->prefix, ntopbuf,
                    sizeof(ntopbuf))) {
                        logit(LOG_ERR, "%s: inet_ntop failed", __func__);
                        exit(EXIT_FAILURE);
                }
                logit(LOG_DEBUG,
                       "%s: add %s/%d to prefix list on %s",
                       __func__, ntopbuf, pp->prefixlen, rai->ifname);

                /* set other fields with protocol defaults */
                pp->validlifetime = DEF_ADVVALIDLIFETIME;
                pp->preflifetime = DEF_ADVPREFERREDLIFETIME;
                pp->onlinkflg = 1;
                pp->autoconfflg = 1;
                pp->origin = PREFIX_FROM_KERNEL;
                pp->rainfo = rai;

                /* link into chain */
                TAILQ_INSERT_TAIL(&rai->prefix, pp, next);
                rai->pfxs++;
        }

        freeifaddrs(ifap);
}

static void
makeentry(char *buf, size_t len, int id, const char *string)
{

        if (id < 0)
                strlcpy(buf, string, len);
        else
                snprintf(buf, len, "%s%d", string, id);
}

/*
 * Delete a prefix to the list of specified interface and reconstruct
 * the outgoing packet.
 * The prefix must be in the list.
 */
void
delete_prefix(struct prefix *prefix)
{
        char ntopbuf[INET6_ADDRSTRLEN];
        struct rainfo *rai = prefix->rainfo;

        TAILQ_REMOVE(&rai->prefix, prefix, next);
        rai->pfxs--;
        logit(LOG_DEBUG, "%s: prefix %s/%d was deleted on %s",
               __func__, inet_ntop(AF_INET6, &prefix->prefix,
                                       ntopbuf, INET6_ADDRSTRLEN),
               prefix->prefixlen, rai->ifname);
        rtadvd_remove_timer(&prefix->timer);
        free(prefix);
}

void
invalidate_prefix(struct prefix *prefix)
{
        char ntopbuf[INET6_ADDRSTRLEN];
        struct timespec timo;
        struct rainfo *rai = prefix->rainfo;

        if (prefix->timer) {    /* sanity check */
                logit(LOG_ERR,
                    "%s: assumption failure: timer already exists",
                    __func__);
                exit(EXIT_FAILURE);
        }

        logit(LOG_DEBUG, "%s: prefix %s/%d was invalidated on %s, "
            "will expire in %ld seconds", __func__,
            inet_ntop(AF_INET6, &prefix->prefix, ntopbuf, INET6_ADDRSTRLEN),
            prefix->prefixlen, rai->ifname, (long)prefix_timo);

        /* set the expiration timer */
        prefix->timer = rtadvd_add_timer(prefix_timeout, NULL, prefix, NULL);
        if (prefix->timer == NULL) {
                logit(LOG_ERR, "%s: failed to add a timer for a prefix. "
                    "remove the prefix", __func__);
                delete_prefix(prefix);
        }
        timo.tv_sec = prefix_timo;
        timo.tv_nsec = 0;
        rtadvd_set_timer(&timo, prefix->timer);
}

static struct rtadvd_timer *
prefix_timeout(void *arg)
{
        struct prefix *prefix = (struct prefix *)arg;

        delete_prefix(prefix);

        return(NULL);
}

void
update_prefix(struct prefix * prefix)
{
        char ntopbuf[INET6_ADDRSTRLEN];
        struct rainfo *rai = prefix->rainfo;

        if (prefix->timer == NULL) { /* sanity check */
                logit(LOG_ERR,
                    "%s: assumption failure: timer does not exist",
                    __func__);
                exit(EXIT_FAILURE);
        }

        logit(LOG_DEBUG, "%s: prefix %s/%d was re-enabled on %s",
            __func__, inet_ntop(AF_INET6, &prefix->prefix, ntopbuf,
            INET6_ADDRSTRLEN), prefix->prefixlen, rai->ifname);

        /* stop the expiration timer */
        rtadvd_remove_timer(&prefix->timer);
}

/*
 * Add a prefix to the list of specified interface and reconstruct
 * the outgoing packet.
 * The prefix must not be in the list.
 * XXX: other parameters of the prefix(e.g. lifetime) should be
 * able to be specified.
 */
void
add_prefix(struct rainfo *rai, int ifindex, const struct in6_addr *addr,
    int plen)
{
        struct prefix *prefix;
        char ntopbuf[INET6_ADDRSTRLEN];

        if ((prefix = calloc(1, sizeof(*prefix))) == NULL) {
                logit(LOG_ERR, "%s: memory allocation failed",
                       __func__);
                return;         /* XXX: error or exit? */
        }
        prefix->prefix = *addr;
        prefix->prefixlen = plen;
        prefix->validlifetime = DEF_ADVVALIDLIFETIME;
        prefix->preflifetime = DEF_ADVPREFERREDLIFETIME;
        prefix->onlinkflg = 1;
        prefix->autoconfflg = 0;
        prefix->origin = PREFIX_FROM_DYNAMIC;

        prefix->rainfo = rai;
        TAILQ_INSERT_TAIL(&rai->prefix, prefix, next);
        rai->pfxs++;

        logit(LOG_DEBUG, "%s: new prefix %s/%d was added on %s",
               __func__, inet_ntop(AF_INET6, addr, ntopbuf, INET6_ADDRSTRLEN),
               plen, rai->ifname);

        /* free the previous packet */
        free(rai->ra_data);
        rai->ra_data = NULL;

        /* reconstruct the packet */
        make_packet(rai);
}

void
make_packet(struct rainfo *rainfo)
{
        size_t packlen, lladdroptlen = 0;
        char *buf;
        struct nd_router_advert *ra;
        struct nd_opt_prefix_info *ndopt_pi;
        struct nd_opt_mtu *ndopt_mtu;
        struct prefix *pfx;
        struct nd_opt_route_info *ndopt_rti;
        struct rtinfo *rti;
        struct nd_opt_rdnss *ndopt_rdnss;
        struct rdnss *rdns;
        struct rdnss_addr *rdnsa;
        struct nd_opt_dnssl *ndopt_dnssl;
        struct dnssl *dnsl;
        struct dnssl_domain *dnsd;
        size_t len, plen;

        /* calculate total length */
        packlen = sizeof(struct nd_router_advert);
        if (rainfo->advlinkopt) {
                if ((lladdroptlen = lladdropt_length(rainfo->sdl)) == 0) {
                        logit(LOG_INFO,
                               "%s: link-layer address option has"
                               " null length on %s.  Treat as not included.",
                               __func__, rainfo->ifname);
                        rainfo->advlinkopt = 0;
                }
                packlen += lladdroptlen;
        }
        if (TAILQ_FIRST(&rainfo->prefix) != NULL)
                packlen += sizeof(struct nd_opt_prefix_info) * rainfo->pfxs;
        if (rainfo->linkmtu)
                packlen += sizeof(struct nd_opt_mtu);
        TAILQ_FOREACH(rti, &rainfo->route, next)
                packlen += sizeof(struct nd_opt_route_info) +
                           ((rti->prefixlen + 0x3f) >> 6) * 8;

        TAILQ_FOREACH(rdns, &rainfo->rdnss, next) {
                packlen += sizeof(struct nd_opt_rdnss);
                TAILQ_FOREACH(rdnsa, &rdns->list, next)
                        packlen += sizeof(rdnsa->addr);
        }
        TAILQ_FOREACH(dnsl, &rainfo->dnssl, next) {
                packlen += sizeof(struct nd_opt_dnssl);
                len = 0;
                TAILQ_FOREACH(dnsd, &dnsl->list, next)
                        len += dnsd->len;
                len += len % 8 ? 8 - len % 8 : 0;
                packlen += len;
        }

        /* allocate memory for the packet */
        if ((buf = realloc(rainfo->ra_data, packlen)) == NULL) {
                logit(LOG_ERR,
                       "%s: can't get enough memory for an RA packet %m",
                       __func__);
                exit(EXIT_FAILURE);
        }
        rainfo->ra_data = buf;
        /* XXX: what if packlen > 576? */
        rainfo->ra_datalen = packlen;
#define CHECKLEN(size) \
        do { \
                if (buf + size > rainfo->ra_data + packlen) { \
                        logit(LOG_ERR, \
                            "%s: @%d RA packet does not fit in %zu",\
                            __func__, __LINE__, packlen); \
                        exit(EXIT_FAILURE); \
                } \
        } while (0)
        /*
         * construct the packet
         */
        CHECKLEN(sizeof(*ra));
        ra = (struct nd_router_advert *)buf;
        ra->nd_ra_type = ND_ROUTER_ADVERT;
        ra->nd_ra_code = 0;
        ra->nd_ra_cksum = 0;
        ra->nd_ra_curhoplimit = (uint8_t)(0xff & rainfo->hoplimit);
        ra->nd_ra_flags_reserved = 0; /* just in case */
        /*
         * XXX: the router preference field, which is a 2-bit field, should be
         * initialized before other fields.
         */
        ra->nd_ra_flags_reserved = 0xff & rainfo->rtpref;
        ra->nd_ra_flags_reserved |=
                rainfo->managedflg ? ND_RA_FLAG_MANAGED : 0;
        ra->nd_ra_flags_reserved |=
                rainfo->otherflg ? ND_RA_FLAG_OTHER : 0;
        ra->nd_ra_router_lifetime = htons(rainfo->lifetime);
        ra->nd_ra_reachable = htonl(rainfo->reachabletime);
        ra->nd_ra_retransmit = htonl(rainfo->retranstimer);
        buf += sizeof(*ra);

        if (rainfo->advlinkopt) {
                CHECKLEN(sizeof(struct nd_opt_hdr));
                lladdropt_fill(rainfo->sdl, (struct nd_opt_hdr *)buf);
                buf += lladdroptlen;
        }

        if (rainfo->linkmtu) {
                CHECKLEN(sizeof(*ndopt_mtu));
                ndopt_mtu = (struct nd_opt_mtu *)buf;
                ndopt_mtu->nd_opt_mtu_type = ND_OPT_MTU;
                ndopt_mtu->nd_opt_mtu_len = 1;
                ndopt_mtu->nd_opt_mtu_reserved = 0;
                ndopt_mtu->nd_opt_mtu_mtu = htonl(rainfo->linkmtu);
                buf += sizeof(struct nd_opt_mtu);
        }

        TAILQ_FOREACH(pfx, &rainfo->prefix, next) {
                uint32_t vltime, pltime;
                struct timespec now;

                CHECKLEN(sizeof(*ndopt_pi));
                ndopt_pi = (struct nd_opt_prefix_info *)buf;
                ndopt_pi->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
                ndopt_pi->nd_opt_pi_len = 4;
                ndopt_pi->nd_opt_pi_prefix_len = pfx->prefixlen;
                ndopt_pi->nd_opt_pi_flags_reserved = 0;
                if (pfx->onlinkflg)
                        ndopt_pi->nd_opt_pi_flags_reserved |=
                                ND_OPT_PI_FLAG_ONLINK;
                if (pfx->autoconfflg)
                        ndopt_pi->nd_opt_pi_flags_reserved |=
                                ND_OPT_PI_FLAG_AUTO;
                if (pfx->timer)
                        vltime = 0;
                else {
                        if (pfx->vltimeexpire || pfx->pltimeexpire)
                                prog_clock_gettime(CLOCK_MONOTONIC, &now);
                        if (pfx->vltimeexpire == 0)
                                vltime = pfx->validlifetime;
                        else
                                vltime = (pfx->vltimeexpire > now.tv_sec) ?
                                    pfx->vltimeexpire - now.tv_sec : 0;
                }
                if (pfx->timer)
                        pltime = 0;
                else {
                        if (pfx->pltimeexpire == 0)
                                pltime = pfx->preflifetime;
                        else
                                pltime = (pfx->pltimeexpire > now.tv_sec) ? 
                                    pfx->pltimeexpire - now.tv_sec : 0;
                }
                if (vltime < pltime) {
                        /*
                         * this can happen if vltime is decrement but pltime
                         * is not.
                         */
                        pltime = vltime;
                }
                ndopt_pi->nd_opt_pi_valid_time = htonl(vltime);
                ndopt_pi->nd_opt_pi_preferred_time = htonl(pltime);
                ndopt_pi->nd_opt_pi_reserved2 = 0;
                ndopt_pi->nd_opt_pi_prefix = pfx->prefix;

                buf += sizeof(struct nd_opt_prefix_info);
        }

        TAILQ_FOREACH(rti, &rainfo->route, next) {
                uint8_t psize = (rti->prefixlen + 0x3f) >> 6;

                CHECKLEN(sizeof(*ndopt_rti));
                ndopt_rti = (struct nd_opt_route_info *)buf;
                ndopt_rti->nd_opt_rti_type = ND_OPT_ROUTE_INFO;
                ndopt_rti->nd_opt_rti_len = 1 + psize;
                ndopt_rti->nd_opt_rti_prefixlen = rti->prefixlen;
                ndopt_rti->nd_opt_rti_flags = 0xff & rti->rtpref;
                ndopt_rti->nd_opt_rti_lifetime = htonl(rti->ltime);
                memcpy(ndopt_rti + 1, &rti->prefix, psize * 8);
                buf += sizeof(struct nd_opt_route_info) + psize * 8;
        }

        TAILQ_FOREACH(rdns, &rainfo->rdnss, next) {
                CHECKLEN(sizeof(*ndopt_rdnss));
                ndopt_rdnss = (struct nd_opt_rdnss *)buf;
                ndopt_rdnss->nd_opt_rdnss_type = ND_OPT_RDNSS;
                ndopt_rdnss->nd_opt_rdnss_len = 1;
                ndopt_rdnss->nd_opt_rdnss_reserved = 0;
                ndopt_rdnss->nd_opt_rdnss_lifetime = htonl(rdns->lifetime);
                buf += sizeof(*ndopt_rdnss);

                TAILQ_FOREACH(rdnsa, &rdns->list, next) {
                        CHECKLEN(sizeof(rdnsa->addr));
                        memcpy(buf, &rdnsa->addr, sizeof(rdnsa->addr));
                        ndopt_rdnss->nd_opt_rdnss_len += 2;
                        buf += sizeof(rdnsa->addr);
                }
        }

        TAILQ_FOREACH(dnsl, &rainfo->dnssl, next) {
                CHECKLEN(sizeof(*ndopt_dnssl));
                ndopt_dnssl = (struct nd_opt_dnssl *)buf;
                ndopt_dnssl->nd_opt_dnssl_type = ND_OPT_DNSSL;
                ndopt_dnssl->nd_opt_dnssl_len = 0;
                ndopt_dnssl->nd_opt_dnssl_reserved = 0;
                ndopt_dnssl->nd_opt_dnssl_lifetime = htonl(dnsl->lifetime);
                buf += sizeof(*ndopt_dnssl);

                TAILQ_FOREACH(dnsd, &dnsl->list, next) {
                        CHECKLEN(dnsd->len);
                        memcpy(buf, dnsd->domain, dnsd->len);
                        buf += dnsd->len;
                }
                /* Ensure our length is padded correctly */
                len = buf - (char *)ndopt_dnssl;
                plen = len % 8 ? 8 - len % 8 : 0;
                CHECKLEN(plen);
                memset(buf, 0, plen);
                buf += plen;
                ndopt_dnssl->nd_opt_dnssl_len = (len + plen) / 8;
        }
        memset(buf, 0, packlen - (buf - rainfo->ra_data));
}

static int
getinet6sysctl(int code)
{
        const int mib[] = { CTL_NET, PF_INET6, IPPROTO_IPV6, code };
        int value;
        size_t size;

        size = sizeof(value);
        if (prog_sysctl(mib, __arraycount(mib), &value, &size, NULL, 0) == -1) {
                logit(LOG_ERR, "%s: failed to get ip6 sysctl(%d): %m",
                       __func__, code);
                return -1;
        }
        return value;
}