/*      $KAME: rtsol.c,v 1.12 2001/11/12 11:47:11 jinmei Exp $  */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/usr.sbin/rtsold/rtsol.c,v 1.1.2.4 2002/04/24 10:22:30 suz Exp $
 * $DragonFly: src/usr.sbin/rtsold/rtsol.c,v 1.7 2008/11/02 21:52:46 swildner Exp $
 */

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

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

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

#include <arpa/inet.h>

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

#define ALLROUTER "ff02::2"

static struct msghdr rcvmhdr;
static struct msghdr sndmhdr;
static struct iovec rcviov[2];
static struct iovec sndiov[2];
static struct sockaddr_in6 from;

int rssock;

static struct sockaddr_in6 sin6_allrouters = {
        sizeof(sin6_allrouters),
        AF_INET6,
        0,
        0,
        IN6ADDR_ANY_INIT,
        0
};

int
sockopen(void)
{
        int on;
        struct icmp6_filter filt;
        static u_char answer[1500];
        int rcvcmsglen, sndcmsglen;
        static u_char *rcvcmsgbuf = NULL, *sndcmsgbuf = NULL;

        sndcmsglen = rcvcmsglen = CMSG_SPACE(sizeof(struct in6_pktinfo)) +
                CMSG_SPACE(sizeof(int));
        if (rcvcmsgbuf == NULL && (rcvcmsgbuf = malloc(rcvcmsglen)) == NULL) {
                warnmsg(LOG_ERR, __func__,
                        "malloc for receive msghdr failed");
                return(-1);
        }
        if (sndcmsgbuf == NULL && (sndcmsgbuf = malloc(sndcmsglen)) == NULL) { 
                warnmsg(LOG_ERR, __func__,
                        "malloc for send msghdr failed");
                return(-1);
        }
        memset(&sin6_allrouters, 0, sizeof(struct sockaddr_in6));
        sin6_allrouters.sin6_family = AF_INET6;
        sin6_allrouters.sin6_len = sizeof(sin6_allrouters);
        if (inet_pton(AF_INET6, ALLROUTER,
                      &sin6_allrouters.sin6_addr.s6_addr) != 1) {
                warnmsg(LOG_ERR, __func__, "inet_pton failed for %s",
                       ALLROUTER);
                return(-1);
        }

        if ((rssock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0) {
                warnmsg(LOG_ERR, __func__, "socket: %s", strerror(errno));
                return(-1);
        }

        /* specify to tell receiving interface */
        on = 1;
#ifdef IPV6_RECVPKTINFO
        if (setsockopt(rssock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on,
                       sizeof(on)) < 0) {
                warnmsg(LOG_ERR, __func__, "IPV6_RECVPKTINFO: %s",
                       strerror(errno));
                exit(1);
        }
#else  /* old adv. API */
        if (setsockopt(rssock, IPPROTO_IPV6, IPV6_PKTINFO, &on,
                       sizeof(on)) < 0) {
                warnmsg(LOG_ERR, __func__, "IPV6_PKTINFO: %s",
                       strerror(errno));
                exit(1);
        }
#endif 

        on = 1;
        /* specify to tell value of hoplimit field of received IP6 hdr */
#ifdef IPV6_RECVHOPLIMIT
        if (setsockopt(rssock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on,
                       sizeof(on)) < 0) {
                warnmsg(LOG_ERR, __func__, "IPV6_RECVHOPLIMIT: %s",
                       strerror(errno));
                exit(1);
        }
#else  /* old adv. API */
        if (setsockopt(rssock, IPPROTO_IPV6, IPV6_HOPLIMIT, &on,
                       sizeof(on)) < 0) {
                warnmsg(LOG_ERR, __func__, "IPV6_HOPLIMIT: %s",
                       strerror(errno));
                exit(1);
        }
#endif 

        /* specfiy to accept only router advertisements on the socket */
        ICMP6_FILTER_SETBLOCKALL(&filt);
        ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
        if (setsockopt(rssock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt,
                       sizeof(filt)) == -1) {
                warnmsg(LOG_ERR, __func__, "setsockopt(ICMP6_FILTER): %s",
                       strerror(errno));
                return(-1);
        }

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

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

        return(rssock);
}

void
sendpacket(struct ifinfo *ifinfo)
{
        ssize_t i;
        struct cmsghdr *cm;
        struct in6_pktinfo *pi;

        sndmhdr.msg_name = (caddr_t)&sin6_allrouters;
        sndmhdr.msg_iov[0].iov_base = (caddr_t)ifinfo->rs_data;
        sndmhdr.msg_iov[0].iov_len = ifinfo->rs_datalen;

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

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

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

        warnmsg(LOG_DEBUG,
               __func__, "send RS on %s, whose state is %d",
               ifinfo->ifname, ifinfo->state);

        i = sendmsg(rssock, &sndmhdr, 0);

        if (i < 0 || (size_t)i != ifinfo->rs_datalen) {
                /*
                 * ENETDOWN is not so serious, especially when using several
                 * network cards on a mobile node. We ignore it.
                 */
                if (errno != ENETDOWN || dflag > 0)
                        warnmsg(LOG_ERR, __func__, "sendmsg on %s: %s",
                                ifinfo->ifname, strerror(errno));
        }

        /* update counter */
        ifinfo->probes++;
}

void
rtsol_input(int s)
{
        ssize_t i;
        int *hlimp = NULL;
        struct icmp6_hdr *icp;
        int ifindex = 0;
        struct cmsghdr *cm;
        struct in6_pktinfo *pi = NULL;
        struct ifinfo *ifi = NULL;
        u_char ntopbuf[INET6_ADDRSTRLEN], ifnamebuf[IFNAMSIZ];

        /* get message */
        if ((i = recvmsg(s, &rcvmhdr, 0)) < 0) {
                warnmsg(LOG_ERR, __func__, "recvmsg: %s", strerror(errno));
                return;
        }

        /* extract optional information via Advanced API */
        for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&rcvmhdr);
             cm;
             cm = (struct cmsghdr *)CMSG_NXTHDR(&rcvmhdr, cm)) {
                if (cm->cmsg_level == IPPROTO_IPV6 &&
                    cm->cmsg_type == IPV6_PKTINFO &&
                    cm->cmsg_len == CMSG_LEN(sizeof(struct in6_pktinfo))) {
                        pi = (struct in6_pktinfo *)(CMSG_DATA(cm));
                        ifindex = pi->ipi6_ifindex;
                }
                if (cm->cmsg_level == IPPROTO_IPV6 &&
                    cm->cmsg_type == IPV6_HOPLIMIT &&
                    cm->cmsg_len == CMSG_LEN(sizeof(int)))
                        hlimp = (int *)CMSG_DATA(cm);
        }

        if (ifindex == 0) {
                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)i < sizeof(struct nd_router_advert)) {
                warnmsg(LOG_ERR,
                       __func__, "packet size(%zd) is too short", i);
                return;
        }

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

        if (icp->icmp6_type != ND_ROUTER_ADVERT) {
                warnmsg(LOG_ERR, __func__,
                        "invalid icmp type(%d) from %s on %s", icp->icmp6_type,
                       inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                                 INET6_ADDRSTRLEN),
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        if (icp->icmp6_code != 0) {
                warnmsg(LOG_ERR, __func__,
                        "invalid icmp code(%d) from %s on %s", icp->icmp6_code,
                       inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                                 INET6_ADDRSTRLEN),
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        if (*hlimp != 255) {
                warnmsg(LOG_NOTICE, __func__,
                        "invalid RA with hop limit(%d) from %s on %s",
                       *hlimp,
                       inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                                 INET6_ADDRSTRLEN),
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        if (pi && !IN6_IS_ADDR_LINKLOCAL(&from.sin6_addr)) {
                warnmsg(LOG_NOTICE, __func__,
                        "invalid RA with non link-local source from %s on %s",
                       inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                                 INET6_ADDRSTRLEN),
                       if_indextoname(pi->ipi6_ifindex, ifnamebuf));
                return;
        }

        /* xxx: more validation? */

        if ((ifi = find_ifinfo(pi->ipi6_ifindex)) == NULL) {
                warnmsg(LOG_NOTICE, __func__,
                        "received RA from %s on an unexpected IF(%s)",
                       inet_ntop(AF_INET6, &from.sin6_addr, ntopbuf,
                                 INET6_ADDRSTRLEN),
                       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,
                         INET6_ADDRSTRLEN),
               ifi->ifname, ifi->state);

        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;
        }
}