/*      $KAME: rrenum.c,v 1.12 2002/06/10 19:59:47 itojun Exp $ */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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/types.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/icmp6.h>

#include <arpa/inet.h>

#include <errno.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <syslog.h>
#include "rtadvd.h"
#include "rrenum.h"
#include "if.h"

#define RR_ISSET_SEGNUM(segnum_bits, segnum) \
        ((((segnum_bits)[(segnum) >> 5]) & (1 << ((segnum) & 31))) != 0)
#define RR_SET_SEGNUM(segnum_bits, segnum) \
        (((segnum_bits)[(segnum) >> 5]) |= (1 << ((segnum) & 31)))

struct rr_operation {
        u_long  rro_seqnum;
        u_long  rro_segnum_bits[8];
};

static struct rr_operation rro;
static int rr_rcvifindex;
static int rrcmd2pco[RPM_PCO_MAX] = {
        0,
        SIOCAIFPREFIX_IN6,
        SIOCCIFPREFIX_IN6,
        SIOCSGIFPREFIX_IN6
};
static int s = -1;

/*
 * Check validity of a Prefix Control Operation(PCO).
 * return 0 on success, 1 on failure.
 */
static int
rr_pco_check(int len, struct rr_pco_match *rpm)
{
        struct rr_pco_use *rpu, *rpulim;
        int checklen;

        /* rpm->rpm_len must be (4N * 3) as router-renum-05.txt */
        if ((rpm->rpm_len - 3) < 0 || /* must be at least 3 */
            (rpm->rpm_len - 3) & 0x3) { /* must be multiple of 4 */
                syslog(LOG_WARNING, "<%s> rpm_len %d is not 4N * 3",
                    __func__, rpm->rpm_len);
                return (1);
        }
        /* rpm->rpm_code must be valid value */
        switch (rpm->rpm_code) {
        case RPM_PCO_ADD:
        case RPM_PCO_CHANGE:
        case RPM_PCO_SETGLOBAL:
                break;
        default:
                syslog(LOG_WARNING, "<%s> unknown rpm_code %d", __func__,
                    rpm->rpm_code);
                return (1);
        }
        /* rpm->rpm_matchlen must be 0 to 128 inclusive */
        if (rpm->rpm_matchlen > 128) {
                syslog(LOG_WARNING, "<%s> rpm_matchlen %d is over 128",
                    __func__, rpm->rpm_matchlen);
                return (1);
        }

        /*
         * rpu->rpu_uselen, rpu->rpu_keeplen, and sum of them must be
         * between 0 and 128 inclusive
         */
        for (rpu = (struct rr_pco_use *)(rpm + 1),
             rpulim = (struct rr_pco_use *)((char *)rpm + len);
             rpu < rpulim;
             rpu += 1) {
                checklen = rpu->rpu_uselen;
                checklen += rpu->rpu_keeplen;
                /*
                 * omit these check, because either of rpu_uselen
                 * and rpu_keeplen is unsigned char
                 *  (128 > rpu_uselen > 0)
                 *  (128 > rpu_keeplen > 0)
                 *  (rpu_uselen + rpu_keeplen > 0)
                 */
                if (checklen > 128) {
                        syslog(LOG_WARNING, "<%s> sum of rpu_uselen %d and"
                            " rpu_keeplen %d is %d(over 128)",
                            __func__, rpu->rpu_uselen, rpu->rpu_keeplen,
                            rpu->rpu_uselen + rpu->rpu_keeplen);
                        return (1);
                }
        }
        return (0);
}

static void
do_use_prefix(int len, struct rr_pco_match *rpm,
        struct in6_rrenumreq *irr, int ifindex)
{
        struct rr_pco_use *rpu, *rpulim;
        struct rainfo *rai;
        struct ifinfo *ifi;
        struct prefix *pfx;

        rpu = (struct rr_pco_use *)(rpm + 1);
        rpulim = (struct rr_pco_use *)((char *)rpm + len);

        if (rpu == rpulim) {    /* no use prefix */
                if (rpm->rpm_code == RPM_PCO_ADD)
                        return;

                irr->irr_u_uselen = 0;
                irr->irr_u_keeplen = 0;
                irr->irr_raf_mask_onlink = 0;
                irr->irr_raf_mask_auto = 0;
                irr->irr_vltime = 0;
                irr->irr_pltime = 0;
                memset(&irr->irr_flags, 0, sizeof(irr->irr_flags));
                irr->irr_useprefix.sin6_len = 0; /* let it mean, no addition */
                irr->irr_useprefix.sin6_family = 0;
                irr->irr_useprefix.sin6_addr = in6addr_any;
                if (ioctl(s, rrcmd2pco[rpm->rpm_code], (caddr_t)irr) < 0 &&
                    errno != EADDRNOTAVAIL)
                        syslog(LOG_ERR, "<%s> ioctl: %s", __func__,
                            strerror(errno));
                return;
        }

        for (rpu = (struct rr_pco_use *)(rpm + 1),
             rpulim = (struct rr_pco_use *)((char *)rpm + len);
             rpu < rpulim;
             rpu += 1) {
                /* init in6_rrenumreq fields */
                irr->irr_u_uselen = rpu->rpu_uselen;
                irr->irr_u_keeplen = rpu->rpu_keeplen;
                irr->irr_raf_mask_onlink =
                    !!(rpu->rpu_ramask & ICMP6_RR_PCOUSE_RAFLAGS_ONLINK);
                irr->irr_raf_mask_auto =
                    !!(rpu->rpu_ramask & ICMP6_RR_PCOUSE_RAFLAGS_AUTO);
                irr->irr_vltime = ntohl(rpu->rpu_vltime);
                irr->irr_pltime = ntohl(rpu->rpu_pltime);
                irr->irr_raf_onlink =
                    (rpu->rpu_raflags & ICMP6_RR_PCOUSE_RAFLAGS_ONLINK) == 0 ?
                    0 : 1;
                irr->irr_raf_auto =
                    (rpu->rpu_raflags & ICMP6_RR_PCOUSE_RAFLAGS_AUTO) == 0 ?
                    0 : 1;
                irr->irr_rrf_decrvalid =
                    (rpu->rpu_flags & ICMP6_RR_PCOUSE_FLAGS_DECRVLTIME) == 0 ?
                    0 : 1;
                irr->irr_rrf_decrprefd =
                    (rpu->rpu_flags & ICMP6_RR_PCOUSE_FLAGS_DECRPLTIME) == 0 ?
                    0 : 1;
                irr->irr_useprefix.sin6_len = sizeof(irr->irr_useprefix);
                irr->irr_useprefix.sin6_family = AF_INET6;
                irr->irr_useprefix.sin6_addr = rpu->rpu_prefix;

                if (ioctl(s, rrcmd2pco[rpm->rpm_code], (caddr_t)irr) < 0 &&
                    errno != EADDRNOTAVAIL)
                        syslog(LOG_ERR, "<%s> ioctl: %s", __func__,
                            strerror(errno));

                /* very adhoc: should be rewritten */
                if (rpm->rpm_code == RPM_PCO_CHANGE &&
                    IN6_ARE_ADDR_EQUAL(&rpm->rpm_prefix, &rpu->rpu_prefix) &&
                    rpm->rpm_matchlen == rpu->rpu_uselen &&
                    rpu->rpu_uselen == rpu->rpu_keeplen) {
                        ifi = if_indextoifinfo(ifindex);
                        if (ifi == NULL || ifi->ifi_rainfo == NULL)
                                continue; /* non-advertising IF */
                        rai = ifi->ifi_rainfo;

                        TAILQ_FOREACH(pfx, &rai->rai_prefix, pfx_next) {
                                struct timespec now;

                                if (prefix_match(&pfx->pfx_prefix,
                                    pfx->pfx_prefixlen, &rpm->rpm_prefix,
                                    rpm->rpm_matchlen)) {
                                        /* change parameters */
                                        pfx->pfx_validlifetime =
                                            ntohl(rpu->rpu_vltime);
                                        pfx->pfx_preflifetime =
                                            ntohl(rpu->rpu_pltime);
                                        if (irr->irr_rrf_decrvalid) {
                                                clock_gettime(CLOCK_MONOTONIC_FAST,
                                                    &now);
                                                pfx->pfx_vltimeexpire =
                                                    now.tv_sec +
                                                    pfx->pfx_validlifetime;
                                        } else
                                                pfx->pfx_vltimeexpire = 0;
                                        if (irr->irr_rrf_decrprefd) {
                                                clock_gettime(CLOCK_MONOTONIC_FAST,
                                                    &now);
                                                pfx->pfx_pltimeexpire =
                                                    now.tv_sec +
                                                    pfx->pfx_preflifetime;
                                        } else
                                                pfx->pfx_pltimeexpire = 0;
                                }
                        }
                }
        }
}

/*
 * process a Prefix Control Operation(PCO).
 * return 0 on success, 1 on failure
 */
static int
do_pco(struct icmp6_router_renum *rr, int len, struct rr_pco_match *rpm)
{
        int ifindex = 0;
        struct in6_rrenumreq irr;
        struct ifinfo *ifi;
        
        if ((rr_pco_check(len, rpm) != 0))
                return (1);

        if (s == -1 && (s = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
                syslog(LOG_ERR, "<%s> socket: %s", __func__,
                    strerror(errno));
                exit(1);
        }

        memset(&irr, 0, sizeof(irr));
        irr.irr_origin = PR_ORIG_RR;
        irr.irr_m_len = rpm->rpm_matchlen;
        irr.irr_m_minlen = rpm->rpm_minlen;
        irr.irr_m_maxlen = rpm->rpm_maxlen;
        irr.irr_matchprefix.sin6_len = sizeof(irr.irr_matchprefix);
        irr.irr_matchprefix.sin6_family = AF_INET6;
        irr.irr_matchprefix.sin6_addr = rpm->rpm_prefix;

        while (if_indextoname(++ifindex, irr.irr_name)) {
                ifi = if_indextoifinfo(ifindex);
                if (ifi == NULL) {
                        syslog(LOG_ERR, "<%s> ifindex not found.",
                            __func__);
                        return (1);
                }
                /*
                 * if ICMP6_RR_FLAGS_FORCEAPPLY(A flag) is 0 and
                 * IFF_UP is off, the interface is not applied
                 */
                if ((rr->rr_flags & ICMP6_RR_FLAGS_FORCEAPPLY) == 0 &&
                    (ifi->ifi_flags & IFF_UP) == 0)
                        continue;
                /* TODO: interface scope check */
                do_use_prefix(len, rpm, &irr, ifindex);
        }
        if (errno == ENXIO)
                return (0);
        else if (errno) {
                syslog(LOG_ERR, "<%s> if_indextoname: %s", __func__,
                    strerror(errno));
                return (1);
        }
        return (0);
}

/*
 * call do_pco() for each Prefix Control Operations(PCOs) in a received
 * Router Renumbering Command packet.
 * return 0 on success, 1 on failure
 */
static int
do_rr(int len, struct icmp6_router_renum *rr)
{
        struct rr_pco_match *rpm;
        char *cp, *lim;

        lim = (char *)rr + len;
        cp = (char *)(rr + 1);
        len -= sizeof(struct icmp6_router_renum);

        update_ifinfo(&ifilist, UPDATE_IFINFO_ALL);

        while (cp < lim) {
                int rpmlen;

                rpm = (struct rr_pco_match *)cp;
                if ((size_t)len < sizeof(struct rr_pco_match)) {
                    tooshort:
                        syslog(LOG_ERR, "<%s> pkt too short. left len = %d. "
                            "garbage at end of pkt?", __func__, len);
                        return (1);
                }
                rpmlen = rpm->rpm_len << 3;
                if (len < rpmlen)
                        goto tooshort;

                if (do_pco(rr, rpmlen, rpm)) {
                        syslog(LOG_WARNING, "<%s> invalid PCO", __func__);
                        goto next;
                }

            next:
                cp += rpmlen;
                len -= rpmlen;
        }

        return (0);
}

/*
 * check validity of a router renumbering command packet
 * return 0 on success, 1 on failure
 */
static int
rr_command_check(int len, struct icmp6_router_renum *rr, struct in6_addr *from,
        struct in6_addr *dst)
{
        u_char ntopbuf[INET6_ADDRSTRLEN];

        /* omit rr minimal length check. hope kernel have done it. */
        /* rr_command length check */
        if ((size_t)len < (sizeof(struct icmp6_router_renum) +
            sizeof(struct rr_pco_match))) {
                syslog(LOG_ERR, "<%s> rr_command len %d is too short",
                    __func__, len);
                return (1);
        }

        /* destination check. only for multicast. omit unicast check. */
        if (IN6_IS_ADDR_MULTICAST(dst) && !IN6_IS_ADDR_MC_LINKLOCAL(dst) &&
            !IN6_IS_ADDR_MC_SITELOCAL(dst)) {
                syslog(LOG_ERR, "<%s> dst mcast addr %s is illegal",
                    __func__,
                    inet_ntop(AF_INET6, dst, ntopbuf, sizeof(ntopbuf)));
                return (1);
        }

        /* seqnum and segnum check */
        if (rro.rro_seqnum > rr->rr_seqnum) {
                syslog(LOG_WARNING,
                    "<%s> rcvd old seqnum %d from %s",
                    __func__, (u_int32_t)ntohl(rr->rr_seqnum),
                   inet_ntop(AF_INET6, from, ntopbuf, sizeof(ntopbuf)));
                return (1);
        }
        if (rro.rro_seqnum == rr->rr_seqnum &&
            (rr->rr_flags & ICMP6_RR_FLAGS_TEST) == 0 &&
            RR_ISSET_SEGNUM(rro.rro_segnum_bits, rr->rr_segnum)) {
                if ((rr->rr_flags & ICMP6_RR_FLAGS_REQRESULT) != 0)
                        syslog(LOG_WARNING,
                            "<%s> rcvd duped segnum %d from %s",
                            __func__, rr->rr_segnum, inet_ntop(AF_INET6, from,
                                ntopbuf, sizeof(ntopbuf)));
                return (0);
        }

        /* update seqnum */
        if (rro.rro_seqnum != rr->rr_seqnum) {
                /* then must be "<" */

                /* init rro_segnum_bits */
                memset(rro.rro_segnum_bits, 0,
                    sizeof(rro.rro_segnum_bits));
        }
        rro.rro_seqnum = rr->rr_seqnum;

        return (0);
}

static void
rr_command_input(int len, struct icmp6_router_renum *rr,
        struct in6_addr *from, struct in6_addr *dst)
{
        /* rr_command validity check */
        if (rr_command_check(len, rr, from, dst))
                goto failed;
        if ((rr->rr_flags & (ICMP6_RR_FLAGS_TEST|ICMP6_RR_FLAGS_REQRESULT)) ==
            ICMP6_RR_FLAGS_TEST)
                return;

        /* do router renumbering */
        if (do_rr(len, rr))
                goto failed;

        /* update segnum */
        RR_SET_SEGNUM(rro.rro_segnum_bits, rr->rr_segnum);

        return;

    failed:
        syslog(LOG_ERR, "<%s> received RR was invalid", __func__);
}

void
rr_input(int len, struct icmp6_router_renum *rr, struct in6_pktinfo *pi,
        struct sockaddr_in6 *from, struct in6_addr *dst)
{
        u_char ntopbuf[2][INET6_ADDRSTRLEN], ifnamebuf[IFNAMSIZ];

        syslog(LOG_DEBUG,
            "<%s> RR received from %s to %s on %s",
            __func__,
            inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf[0] ,sizeof(ntopbuf[0])),
            inet_ntop(AF_INET6, &dst, ntopbuf[1], sizeof(ntopbuf[1])),
            if_indextoname(pi->ipi6_ifindex, ifnamebuf));

        /* packet validation based on Section 4.1 of RFC2894 */
        if ((size_t)len < sizeof(struct icmp6_router_renum)) {
                syslog(LOG_NOTICE,
                    "<%s>: RR short message (size %d) from %s to %s on %s",
                    __func__, len,
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf[0],
                        sizeof(ntopbuf[0])),
                    inet_ntop(AF_INET6, &dst, ntopbuf[1], sizeof(ntopbuf[1])),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        /*
         * If the IPv6 destination address is neither an All Routers multicast
         * address [AARCH] nor one of the receiving router's unicast addresses,
         * the message MUST be discarded and SHOULD be logged to network
         * management.
         * We rely on the kernel input routine for unicast addresses, and thus
         * check multicast destinations only.
         */
        if (IN6_IS_ADDR_MULTICAST(&pi->ipi6_addr) && !IN6_ARE_ADDR_EQUAL(
            &sin6_sitelocal_allrouters.sin6_addr, &pi->ipi6_addr)) {
                syslog(LOG_NOTICE,
                    "<%s>: RR message with invalid destination (%s) "
                    "from %s on %s",
                    __func__,
                    inet_ntop(AF_INET6, &dst, ntopbuf[0], sizeof(ntopbuf[0])),
                    inet_ntop(AF_INET6, &from->sin6_addr, ntopbuf[1],
                              sizeof(ntopbuf[1])),
                    if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        rr_rcvifindex = pi->ipi6_ifindex;

        switch (rr->rr_code) {
        case ICMP6_ROUTER_RENUMBERING_COMMAND:
                rr_command_input(len, rr, &from->sin6_addr, dst);
                /* TODO: send reply msg */
                break;
        case ICMP6_ROUTER_RENUMBERING_RESULT:
                /* RESULT will be processed by rrenumd */
                break;
        case ICMP6_ROUTER_RENUMBERING_SEQNUM_RESET:
                /* TODO: sequence number reset */
                break;
        default:
                syslog(LOG_ERR, "<%s> received unknown code %d",
                    __func__, rr->rr_code);
                break;

        }
}