/*      $KAME: rtsol.c,v 1.27 2003/10/05 00:09:36 itojun Exp $  */

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

#include <net/if.h>
#include <net/route.h>
#include <net/if_dl.h>

#define __BSD_VISIBLE   1       /* IN6ADDR_LINKLOCAL_ALLROUTERS_INIT */
#include <netinet/in.h>
#undef  __BSD_VISIBLE
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>

#include <arpa/inet.h>

#include <capsicum_helpers.h>
#include <netdb.h>
#include <time.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <err.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include "rtsold.h"

static char rsid[IFNAMSIZ + 1 + sizeof(DNSINFO_ORIGIN_LABEL) + 1 + NI_MAXHOST];
struct ifinfo_head_t ifinfo_head = TAILQ_HEAD_INITIALIZER(ifinfo_head);

static void call_script(const char *const *, struct script_msg_head_t *);
static size_t dname_labeldec(char *, size_t, const char *);
static struct ra_opt *find_raopt(struct rainfo *, int, void *, size_t);
static int ra_opt_rdnss_dispatch(struct ifinfo *, struct rainfo *,
    struct script_msg_head_t *, struct script_msg_head_t *);
static char *make_rsid(const char *, const char *, struct rainfo *);

#define _ARGS_MANAGED   managedconf_script, ifi->ifname, rasender
#define _ARGS_OTHER     otherconf_script, ifi->ifname, rasender
#define _ARGS_ALWAYS    alwaysconf_script, ifi->ifname, rasender
#define _ARGS_RESADD    resolvconf_script, "-a", rsid
#define _ARGS_RESDEL    resolvconf_script, "-d", rsid

#define CALL_SCRIPT(name, sm_head) do {                         \
        const char *const sarg[] = { _ARGS_##name, NULL };      \
        call_script(sarg, sm_head);                             \
} while (0)

#define ELM_MALLOC(p, error_action) do {                        \
        p = malloc(sizeof(*p));                                 \
        if (p == NULL) {                                        \
                warnmsg(LOG_ERR, __func__, "malloc failed: %s", \
                    strerror(errno));                           \
                error_action;                                   \
        }                                                       \
        memset(p, 0, sizeof(*p));                               \
} while (0)

int
recvsockopen(void)
{
        struct icmp6_filter filt;
        cap_rights_t rights;
        int on, sock;

        if ((sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0) {
                warnmsg(LOG_ERR, __func__, "socket: %s", strerror(errno));
                goto fail;
        }

        /* Provide info about the receiving interface. */
        on = 1;
        if (setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on,
            sizeof(on)) < 0) {
                warnmsg(LOG_ERR, __func__, "setsockopt(IPV6_RECVPKTINFO): %s",
                    strerror(errno));
                goto fail;
        }

        /* Include the hop limit from the received header. */
        on = 1;
        if (setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on,
            sizeof(on)) < 0) {
                warnmsg(LOG_ERR, __func__, "setsockopt(IPV6_RECVHOPLIMIT): %s",
                    strerror(errno));
                goto fail;
        }

        /* Filter out everything except for Router Advertisements. */
        ICMP6_FILTER_SETBLOCKALL(&filt);
        ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
        if (setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt,
            sizeof(filt)) == -1) {
                warnmsg(LOG_ERR, __func__, "setsockopt(ICMP6_FILTER): %s",
                    strerror(errno));
                goto fail;
        }

        cap_rights_init(&rights, CAP_EVENT, CAP_RECV);
        if (caph_rights_limit(sock, &rights) < 0) {
                warnmsg(LOG_ERR, __func__, "caph_rights_limit(): %s",
                    strerror(errno));
                goto fail;
        }

        return (sock);

fail:
        if (sock >= 0)
                (void)close(sock);
        return (-1);
}

void
rtsol_input(int sock)
{
        uint8_t cmsg[CMSG_SPACE(sizeof(struct in6_pktinfo)) +
            CMSG_SPACE(sizeof(int))];
        struct iovec iov;
        struct msghdr hdr;
        struct sockaddr_in6 from;
        char answer[1500], ntopbuf[INET6_ADDRSTRLEN], ifnamebuf[IFNAMSIZ];
        int l, ifindex = 0, *hlimp = NULL;
        ssize_t msglen;
        struct in6_pktinfo *pi = NULL;
        struct ifinfo *ifi = NULL;
        struct ra_opt *rao = NULL;
        struct icmp6_hdr *icp;
        struct nd_router_advert *nd_ra;
        struct cmsghdr *cm;
        struct rainfo *rai;
        char *p, *raoptp;
        struct in6_addr *addr;
        struct nd_opt_hdr *ndo;
        struct nd_opt_rdnss *rdnss;
        struct nd_opt_dnssl *dnssl;
        size_t len;
        char nsbuf[INET6_ADDRSTRLEN + 1 + IFNAMSIZ + 1];
        char dname[NI_MAXHOST];
        struct timespec lifetime, now;
        int newent_rai, newent_rao;

        memset(&hdr, 0, sizeof(hdr));
        hdr.msg_iov = &iov;
        hdr.msg_iovlen = 1;
        hdr.msg_name = &from;
        hdr.msg_namelen = sizeof(from);
        hdr.msg_control = cmsg;
        hdr.msg_controllen = sizeof(cmsg);

        iov.iov_base = (caddr_t)answer;
        iov.iov_len = sizeof(answer);

        if ((msglen = recvmsg(sock, &hdr, 0)) < 0) {
                warnmsg(LOG_ERR, __func__, "recvmsg: %s", strerror(errno));
                return;
        }

        /* Extract control message info. */
        for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&hdr); cm != NULL;
            cm = (struct cmsghdr *)CMSG_NXTHDR(&hdr, 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 *)(void *)(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 *)(void *)CMSG_DATA(cm);
        }

        if (ifindex == 0) {
                warnmsg(LOG_ERR, __func__,
                    "failed to get receiving interface");
                return;
        }
        if (hlimp == NULL) {
                warnmsg(LOG_ERR, __func__,
                    "failed to get receiving hop limit");
                return;
        }

        if ((size_t)msglen < sizeof(struct nd_router_advert)) {
                warnmsg(LOG_INFO, __func__,
                    "packet size(%zd) is too short", msglen);
                return;
        }

        icp = (struct icmp6_hdr *)iov.iov_base;
        if (icp->icmp6_type != ND_ROUTER_ADVERT) {
                /*
                 * this should not happen because we configured a filter
                 * that only passes RAs on the receiving socket.
                 */
                warnmsg(LOG_ERR, __func__,
                    "invalid icmp type(%d) from %s on %s", icp->icmp6_type,
                    inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                        sizeof(ntopbuf)),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        if (icp->icmp6_code != 0) {
                warnmsg(LOG_INFO, __func__,
                    "invalid icmp code(%d) from %s on %s", icp->icmp6_code,
                    inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                        sizeof(ntopbuf)),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        if (*hlimp != 255) {
                warnmsg(LOG_INFO, __func__,
                    "invalid RA with hop limit(%d) from %s on %s",
                    *hlimp,
                    inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                        sizeof(ntopbuf)),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        if (pi && !IN6_IS_ADDR_LINKLOCAL(&from.sin6_addr)) {
                warnmsg(LOG_INFO, __func__,
                    "invalid RA with non link-local source from %s on %s",
                    inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                        sizeof(ntopbuf)),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        /* xxx: more validation? */

        if ((ifi = find_ifinfo(pi->ipi6_ifindex)) == NULL) {
                warnmsg(LOG_DEBUG, __func__,
                    "received RA from %s on an unexpected IF(%s)",
                    inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                        sizeof(ntopbuf)),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        warnmsg(LOG_DEBUG, __func__,
            "received RA from %s on %s, state is %d",
            inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf, sizeof(ntopbuf)),
            ifi->ifname, ifi->state);

        nd_ra = (struct nd_router_advert *)icp;

        /*
         * Process the "M bit."
         * If the value of ManagedConfigFlag changes from FALSE to TRUE, the
         * host should invoke the stateful autoconfiguration protocol,
         * requesting information.
         * [RFC 4861 Section 4.2]
         * XXX ??? [draft-ietf-v6ops-dhcpv6-slaac-problem-07]
         */
        if (((nd_ra->nd_ra_flags_reserved) & ND_RA_FLAG_MANAGED) &&
            !ifi->managedconfig) {
                const char *rasender = inet_ntop(AF_INET6, &from.sin6_addr,
                    ntopbuf, sizeof(ntopbuf));
                warnmsg(LOG_DEBUG, __func__,
                    "ManagedConfigFlag on %s is turned on", ifi->ifname);
                ifi->managedconfig = 1;
                CALL_SCRIPT(MANAGED, NULL);
        }

        /*
         * Process the "O bit."
         * If the value of OtherConfigFlag changes from FALSE to TRUE, the
         * host should invoke the stateful autoconfiguration protocol,
         * requesting information unless the "M bit" was set as well in
         * which case the "O bit" is redundant.
         * [RFC 4861 Section 4.2]
         */
        if (((nd_ra->nd_ra_flags_reserved) & ND_RA_FLAG_OTHER) &&
            !ifi->otherconfig) {
                const char *rasender = inet_ntop(AF_INET6, &from.sin6_addr,
                    ntopbuf, sizeof(ntopbuf));
                warnmsg(LOG_DEBUG, __func__,
                    "OtherConfigFlag on %s is turned on", ifi->ifname);
                ifi->otherconfig = 1;
                if (!ifi->managedconfig)
                        CALL_SCRIPT(OTHER, NULL);
        }

        /*
         * "Always" script.
         */
        if (!ifi->alwaysconfig) {
                const char *rasender = inet_ntop(AF_INET6, &from.sin6_addr,
                    ntopbuf, sizeof(ntopbuf));
                ifi->alwaysconfig = 1;
                CALL_SCRIPT(ALWAYS, NULL);
        }

        clock_gettime(CLOCK_MONOTONIC_FAST, &now);
        newent_rai = 0;
        rai = find_rainfo(ifi, &from);
        if (rai == NULL) {
                ELM_MALLOC(rai, exit(1));
                rai->rai_ifinfo = ifi;
                TAILQ_INIT(&rai->rai_ra_opt);
                rai->rai_saddr.sin6_family = AF_INET6;
                rai->rai_saddr.sin6_len = sizeof(rai->rai_saddr);
                memcpy(&rai->rai_saddr.sin6_addr, &from.sin6_addr,
                    sizeof(rai->rai_saddr.sin6_addr));
                newent_rai = 1;
        }

#define RA_OPT_NEXT_HDR(x)      (struct nd_opt_hdr *)((char *)(x) + \
                                (((struct nd_opt_hdr *)(x))->nd_opt_len * 8))
        /* Process RA options. */
        warnmsg(LOG_DEBUG, __func__, "Processing RA");
        raoptp = (char *)icp + sizeof(struct nd_router_advert);
        while (raoptp < (char *)icp + msglen) {
                ndo = (struct nd_opt_hdr *)raoptp;
                warnmsg(LOG_DEBUG, __func__, "ndo = %p", raoptp);
                warnmsg(LOG_DEBUG, __func__, "ndo->nd_opt_type = %d",
                    ndo->nd_opt_type);
                warnmsg(LOG_DEBUG, __func__, "ndo->nd_opt_len = %d",
                    ndo->nd_opt_len);

                if (ndo->nd_opt_len == 0) {
                        warnmsg(LOG_INFO, __func__, "invalid option length 0.");
                        break;
                }
                if ((char *)RA_OPT_NEXT_HDR(raoptp) > (char *)icp + msglen) {
                        warnmsg(LOG_INFO, __func__, "option length overflow.");
                        break;
                }

                switch (ndo->nd_opt_type) {
                case ND_OPT_RDNSS:
                        rdnss = (struct nd_opt_rdnss *)raoptp;

                        /*
                         * The option header is 8 bytes long and each address
                         * occupies 16 bytes, so the option length must be
                         * greater than or equal to 24 bytes and an odd multiple
                         * of 8 bytes.  See section 5.1 in RFC 6106.
                         */
                        if (rdnss->nd_opt_rdnss_len < 3 ||
                            rdnss->nd_opt_rdnss_len % 2 == 0) {
                                warnmsg(LOG_INFO, __func__,
                                    "too short RDNSS option in RA from %s "
                                    "was ignored.",
                                inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                                    sizeof(ntopbuf)));
                                break;
                        }

                        addr = (struct in6_addr *)(void *)(raoptp + sizeof(*rdnss));
                        while ((char *)addr < (char *)RA_OPT_NEXT_HDR(raoptp)) {
                                if (inet_ntop(AF_INET6, addr, ntopbuf,
                                        sizeof(ntopbuf)) == NULL) {
                                        warnmsg(LOG_INFO, __func__,
                                            "an invalid address in RDNSS option"
                                            " in RA from %s was ignored.",
                                            inet_ntop(AF_INET6, &from.sin6_addr,
                                                ntopbuf, sizeof(ntopbuf)));
                                        addr++;
                                        continue;
                                }
                                if (IN6_IS_ADDR_LINKLOCAL(addr))
                                        /* XXX: % has to be escaped here */
                                        l = snprintf(nsbuf, sizeof(nsbuf),
                                            "%s%c%s", ntopbuf,
                                            SCOPE_DELIMITER,
                                            ifi->ifname);
                                else
                                        l = snprintf(nsbuf, sizeof(nsbuf),
                                            "%s", ntopbuf);
                                if (l < 0 || (size_t)l >= sizeof(nsbuf)) {
                                        warnmsg(LOG_ERR, __func__,
                                            "address copying error in "
                                            "RDNSS option: %d.", l);
                                        addr++;
                                        continue;
                                }
                                warnmsg(LOG_DEBUG, __func__, "nsbuf = %s",
                                    nsbuf);

                                newent_rao = 0;
                                rao = find_raopt(rai, ndo->nd_opt_type, nsbuf,
                                    strlen(nsbuf));
                                if (rao == NULL) {
                                        ELM_MALLOC(rao, break);
                                        rao->rao_type = ndo->nd_opt_type;
                                        rao->rao_len = strlen(nsbuf);
                                        rao->rao_msg = strdup(nsbuf);
                                        if (rao->rao_msg == NULL) {
                                                warnmsg(LOG_ERR, __func__,
                                                    "strdup failed: %s",
                                                    strerror(errno));
                                                free(rao);
                                                addr++;
                                                continue;
                                        }
                                        newent_rao = 1;
                                }
                                /* Set expiration timer */
                                memset(&rao->rao_expire, 0,
                                    sizeof(rao->rao_expire));
                                memset(&lifetime, 0, sizeof(lifetime));
                                lifetime.tv_sec =
                                    ntohl(rdnss->nd_opt_rdnss_lifetime);
                                TS_ADD(&now, &lifetime, &rao->rao_expire);

                                if (newent_rao)
                                        TAILQ_INSERT_TAIL(&rai->rai_ra_opt,
                                            rao, rao_next);
                                addr++;
                        }
                        break;
                case ND_OPT_DNSSL:
                        dnssl = (struct nd_opt_dnssl *)raoptp;

                        /* Optlen sanity check (Section 5.3.1 in RFC 6106) */
                        if (dnssl->nd_opt_dnssl_len < 2) {
                                warnmsg(LOG_INFO, __func__,
                                        "too short DNSSL option"
                                        "in RA from %s was ignored.",
                                        inet_ntop(AF_INET6, &from.sin6_addr,
                                            ntopbuf, sizeof(ntopbuf)));
                                break;
                        }

                        /*
                         * Ensure NUL-termination in DNSSL in case of
                         * malformed field.
                         */
                        p = (char *)RA_OPT_NEXT_HDR(raoptp);
                        *(p - 1) = '\0';

                        p = raoptp + sizeof(*dnssl);
                        while (1 < (len = dname_labeldec(dname, sizeof(dname),
                            p))) {
                                /* length == 1 means empty string */
                                warnmsg(LOG_DEBUG, __func__, "dname = %s",
                                    dname);

                                newent_rao = 0;
                                rao = find_raopt(rai, ndo->nd_opt_type, dname,
                                    strlen(dname));
                                if (rao == NULL) {
                                        ELM_MALLOC(rao, break);
                                        rao->rao_type = ndo->nd_opt_type;
                                        rao->rao_len = strlen(dname);
                                        rao->rao_msg = strdup(dname);
                                        if (rao->rao_msg == NULL) {
                                                warnmsg(LOG_ERR, __func__,
                                                    "strdup failed: %s",
                                                    strerror(errno));
                                                free(rao);
                                                addr++;
                                                continue;
                                        }
                                        newent_rao = 1;
                                }
                                /* Set expiration timer */
                                memset(&rao->rao_expire, 0,
                                    sizeof(rao->rao_expire));
                                memset(&lifetime, 0, sizeof(lifetime));
                                lifetime.tv_sec =
                                    ntohl(dnssl->nd_opt_dnssl_lifetime);
                                TS_ADD(&now, &lifetime, &rao->rao_expire);

                                if (newent_rao)
                                        TAILQ_INSERT_TAIL(&rai->rai_ra_opt,
                                            rao, rao_next);
                                p += len;
                        }
                        break;
                default:  
                        /* nothing to do for other options */
                        break;
                }
                raoptp = (char *)RA_OPT_NEXT_HDR(raoptp);
        }
        if (newent_rai)
                TAILQ_INSERT_TAIL(&ifi->ifi_rainfo, rai, rai_next);

        ra_opt_handler(ifi);
        ifi->racnt++;

        switch (ifi->state) {
        case IFS_IDLE:          /* should be ignored */
        case IFS_DELAY:         /* right? */
                break;
        case IFS_PROBE:
                ifi->state = IFS_IDLE;
                ifi->probes = 0;
                rtsol_timer_update(ifi);
                break;
        }
}

static char resstr_ns_prefix[] = "nameserver ";
static char resstr_sh_prefix[] = "search ";
static char resstr_nl[] = "\n";
static char resstr_sp[] = " ";

int
ra_opt_handler(struct ifinfo *ifi)
{
        struct ra_opt *rao;
        struct rainfo *rai;
        struct script_msg *smp1, *smp2, *smp3;
        struct timespec now;
        struct script_msg_head_t sm_rdnss_head =
            TAILQ_HEAD_INITIALIZER(sm_rdnss_head);
        struct script_msg_head_t sm_dnssl_head =
            TAILQ_HEAD_INITIALIZER(sm_dnssl_head);

        int dcount, dlen;

        dcount = 0;
        dlen = strlen(resstr_sh_prefix) + strlen(resstr_nl);
        clock_gettime(CLOCK_MONOTONIC_FAST, &now);

        /*
         * All options from multiple RAs with the same or different
         * source addresses on a single interface will be gathered and
         * handled, not overridden.  [RFC 4861 6.3.4]
         */
        TAILQ_FOREACH(rai, &ifi->ifi_rainfo, rai_next) {
                TAILQ_FOREACH(rao, &rai->rai_ra_opt, rao_next) {
                        switch (rao->rao_type) {
                        case ND_OPT_RDNSS:
                                if (TS_CMP(&now, &rao->rao_expire, >)) {
                                        warnmsg(LOG_INFO, __func__,
                                            "expired rdnss entry: %s",
                                            (char *)rao->rao_msg);
                                        break;
                                }
                                ELM_MALLOC(smp1, continue);
                                ELM_MALLOC(smp2, goto free1);
                                ELM_MALLOC(smp3, goto free2);
                                smp1->sm_msg = resstr_ns_prefix;
                                TAILQ_INSERT_TAIL(&sm_rdnss_head, smp1,
                                    sm_next);
                                smp2->sm_msg = rao->rao_msg;
                                TAILQ_INSERT_TAIL(&sm_rdnss_head, smp2,
                                    sm_next);
                                smp3->sm_msg = resstr_nl;
                                TAILQ_INSERT_TAIL(&sm_rdnss_head, smp3,
                                    sm_next);
                                ifi->ifi_rdnss = IFI_DNSOPT_STATE_RECEIVED;
                                break;
                        case ND_OPT_DNSSL:
                                if (TS_CMP(&now, &rao->rao_expire, >)) {
                                        warnmsg(LOG_INFO, __func__,
                                            "expired dnssl entry: %s",
                                            (char *)rao->rao_msg);
                                        break;
                                }
                                dcount++;
                                /* Check resolv.conf(5) restrictions. */
                                if (dcount > 6) {
                                        warnmsg(LOG_INFO, __func__,
                                            "dnssl entry exceeding maximum count (%d>6)"
                                            ": %s", dcount, (char *)rao->rao_msg);
                                        break;
                                }
                                if (256 < dlen + strlen(rao->rao_msg) +
                                    strlen(resstr_sp)) {
                                        warnmsg(LOG_INFO, __func__,
                                            "dnssl entry exceeding maximum length "
                                            "(>256): %s", (char *)rao->rao_msg);
                                        break;
                                }
                                ELM_MALLOC(smp1, continue);
                                ELM_MALLOC(smp2, goto free1);
                                if (TAILQ_EMPTY(&sm_dnssl_head)) {
                                        ELM_MALLOC(smp3, goto free2);
                                        smp3->sm_msg = resstr_sh_prefix;
                                        TAILQ_INSERT_TAIL(&sm_dnssl_head, smp3,
                                            sm_next);
                                }
                                smp1->sm_msg = rao->rao_msg;
                                TAILQ_INSERT_TAIL(&sm_dnssl_head, smp1,
                                    sm_next);
                                smp2->sm_msg = resstr_sp;
                                TAILQ_INSERT_TAIL(&sm_dnssl_head, smp2,
                                    sm_next);
                                dlen += strlen(rao->rao_msg) +
                                    strlen(resstr_sp);
                                ifi->ifi_dnssl = IFI_DNSOPT_STATE_RECEIVED;
                                break;
                        }
                        continue;
free2:
                        free(smp2);
free1:
                        free(smp1);
                }
                /* Call the script for each information source. */
                if (uflag)
                        ra_opt_rdnss_dispatch(ifi, rai, &sm_rdnss_head,
                            &sm_dnssl_head);
        }
        /* Call the script for each interface. */
        if (!uflag)
                ra_opt_rdnss_dispatch(ifi, NULL, &sm_rdnss_head,
                    &sm_dnssl_head);
        return (0);
}

char *
make_rsid(const char *ifname, const char *origin, struct rainfo *rai)
{
        char hbuf[NI_MAXHOST];
        
        if (rai == NULL)
                sprintf(rsid, "%s:%s", ifname, origin);
        else {
                if (!IN6_IS_ADDR_LINKLOCAL(&rai->rai_saddr.sin6_addr))
                        return (NULL);
                if (getnameinfo((struct sockaddr *)&rai->rai_saddr,
                        rai->rai_saddr.sin6_len, hbuf, sizeof(hbuf), NULL, 0,
                        NI_NUMERICHOST) != 0)
                        return (NULL);
                sprintf(rsid, "%s:%s:[%s]", ifname, origin, hbuf);
        }
        warnmsg(LOG_DEBUG, __func__, "rsid = [%s]", rsid);
        return (rsid);
}

int
ra_opt_rdnss_dispatch(struct ifinfo *ifi, struct rainfo *rai,
    struct script_msg_head_t *sm_rdnss_head,
    struct script_msg_head_t *sm_dnssl_head)
{
        struct script_msg *smp1;
        const char *r;
        int error;

        error = 0;
        /* Add \n for DNSSL list. */
        if (!TAILQ_EMPTY(sm_dnssl_head)) {
                ELM_MALLOC(smp1, goto ra_opt_rdnss_freeit);
                smp1->sm_msg = resstr_nl;
                TAILQ_INSERT_TAIL(sm_dnssl_head, smp1, sm_next);
        }
        TAILQ_CONCAT(sm_rdnss_head, sm_dnssl_head, sm_next);

        r = make_rsid(ifi->ifname, DNSINFO_ORIGIN_LABEL, uflag ? rai : NULL);
        if (r == NULL) {
                warnmsg(LOG_ERR, __func__, "make_rsid() failed.  "
                    "Script was not invoked.");
                error = 1;
                goto ra_opt_rdnss_freeit;
        }
        if (!TAILQ_EMPTY(sm_rdnss_head))
                CALL_SCRIPT(RESADD, sm_rdnss_head);
        else if (ifi->ifi_rdnss == IFI_DNSOPT_STATE_RECEIVED ||
            ifi->ifi_dnssl == IFI_DNSOPT_STATE_RECEIVED) {
                CALL_SCRIPT(RESDEL, NULL);
                ifi->ifi_rdnss = IFI_DNSOPT_STATE_NOINFO;
                ifi->ifi_dnssl = IFI_DNSOPT_STATE_NOINFO;
        }

ra_opt_rdnss_freeit:
        /* Clear script message queue. */
        if (!TAILQ_EMPTY(sm_rdnss_head)) {
                while ((smp1 = TAILQ_FIRST(sm_rdnss_head)) != NULL) {
                        TAILQ_REMOVE(sm_rdnss_head, smp1, sm_next);
                        free(smp1);
                }
        }
        if (!TAILQ_EMPTY(sm_dnssl_head)) {
                while ((smp1 = TAILQ_FIRST(sm_dnssl_head)) != NULL) {
                        TAILQ_REMOVE(sm_dnssl_head, smp1, sm_next);
                        free(smp1);
                }
        }
        return (error);
}

static struct ra_opt *
find_raopt(struct rainfo *rai, int type, void *msg, size_t len)
{
        struct ra_opt *rao;

        TAILQ_FOREACH(rao, &rai->rai_ra_opt, rao_next) {
                if (rao->rao_type == type &&
                    rao->rao_len == strlen(msg) &&
                    memcmp(rao->rao_msg, msg, len) == 0)
                        break;
        }

        return (rao);
}

static void
call_script(const char *const argv[], struct script_msg_head_t *sm_head)
{
        struct script_msg *smp;
        ssize_t len;
        int status, wfd;

        if (argv[0] == NULL)
                return;

        wfd = cap_script_run(capscript, argv);
        if (wfd == -1) {
                warnmsg(LOG_ERR, __func__,
                    "failed to run %s: %s", argv[0], strerror(errno));
                return;
        }

        if (sm_head != NULL) {
                TAILQ_FOREACH(smp, sm_head, sm_next) {
                        len = strlen(smp->sm_msg);
                        warnmsg(LOG_DEBUG, __func__, "write to child = %s(%zd)",
                            smp->sm_msg, len);
                        if (write(wfd, smp->sm_msg, len) != len) {
                                warnmsg(LOG_ERR, __func__,
                                    "write to child failed: %s",
                                    strerror(errno));
                                break;
                        }
                }
        }

        (void)close(wfd);

        if (cap_script_wait(capscript, &status) != 0)
                warnmsg(LOG_ERR, __func__, "wait(): %s", strerror(errno));
        else
                warnmsg(LOG_DEBUG, __func__, "script \"%s\" status %d",
                    argv[0], status);
}

#define PERIOD 0x2e
#define hyphenchar(c) ((c) == 0x2d)
#define periodchar(c) ((c) == PERIOD)
#define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) || \
            ((c) >= 0x61 && (c) <= 0x7a))
#define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)

#define borderchar(c) (alphachar(c) || digitchar(c))
#define middlechar(c) (borderchar(c) || hyphenchar(c))

static int
res_hnok(const char *dn)
{
        int pch = PERIOD, ch = *dn++;

        while (ch != '\0') {
                int nch = *dn++;

                if (periodchar(ch)) {
                        ;
                } else if (periodchar(pch)) {
                        if (!borderchar(ch))
                                return (0);
                } else if (periodchar(nch) || nch == '\0') {
                        if (!borderchar(ch))
                                return (0);
                } else {
                        if (!middlechar(ch))
                                return (0);
                }
                pch = ch, ch = nch;
        }
        return (1);
}

/* Decode domain name label encoding in RFC 1035 Section 3.1 */
static size_t
dname_labeldec(char *dst, size_t dlen, const char *src)
{
        size_t len;
        const char *src_origin;
        const char *src_last;
        const char *dst_origin;

        src_origin = src;
        src_last = strchr(src, '\0');
        dst_origin = dst;
        memset(dst, '\0', dlen);
        while ((len = (*src++) & 0x3f) &&
            src + len <= src_last &&
            len + (dst == dst_origin ? 0 : 1) < dlen) {
                if (dst != dst_origin) {
                        *dst++ = '.';
                        dlen--;
                }
                warnmsg(LOG_DEBUG, __func__, "labellen = %zd", len);
                memcpy(dst, src, len);
                src += len;
                dst += len;
                dlen -= len;
        }
        *dst = '\0';

        if (!res_hnok(dst_origin)) {
                warnmsg(LOG_INFO, __func__,
                    "invalid domain name '%s' was ignored", dst_origin);
                return (0);
        }

        return (src - src_origin);
}