/*      $KAME: probe.c,v 1.10 2000/08/13 06:14:59 itojun 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.
 *
 * $FreeBSD: src/usr.sbin/rtsold/probe.c,v 1.2.2.3 2001/07/03 11:02:16 ume Exp $
 * $DragonFly: src/usr.sbin/rtsold/probe.c,v 1.8 2007/05/18 17:05:12 dillon Exp $
 */

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

#include <net/if.h>
#if defined(__DragonFly__)
#include <net/if_var.h>
#endif /* __DragonFly__ >= 3 */

#include <netinet/in.h>
#include <netinet6/in6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>

#include <arpa/inet.h>

#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <syslog.h>
#include <stdlib.h>

#include "rtsold.h"

static struct msghdr sndmhdr;
static struct iovec sndiov[2];
static int probesock;
static void sendprobe(struct in6_addr *addr, int ifindex);


int
probe_init(void)
{
        int scmsglen = CMSG_SPACE(sizeof(struct in6_pktinfo)) +
                CMSG_SPACE(sizeof(int));
        static u_char *sndcmsgbuf = NULL;
        
        if (sndcmsgbuf == NULL &&
            (sndcmsgbuf = (u_char *)malloc(scmsglen)) == NULL) {
                warnmsg(LOG_ERR, __func__, "malloc failed");
                return(-1);
        }

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

        /* make the socket send-only */
        if (shutdown(probesock, SHUT_RD)) {
                warnmsg(LOG_ERR, __func__, "shutdown: %s", strerror(errno));
                return(-1);
        }

        /* 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 = scmsglen;

        return(0);
}

/*
 * Probe if each router in the default router list is still alive. 
 */
void
defrouter_probe(int ifindex)
{
        struct in6_drlist dr;
        int s, i;
        u_char ntopbuf[INET6_ADDRSTRLEN];

        if ((s = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
                warnmsg(LOG_ERR, __func__, "socket: %s", strerror(errno));
                return;
        }
        bzero(&dr, sizeof(dr));
        strcpy(dr.ifname, "lo0"); /* dummy interface */
        if (ioctl(s, SIOCGDRLST_IN6, (caddr_t)&dr) < 0) {
                warnmsg(LOG_ERR, __func__, "ioctl(SIOCGDRLST_IN6): %s",
                       strerror(errno));
                goto closeandend;
        }

        for(i = 0; i < PRLSTSIZ && dr.defrouter[i].if_index; i++) {
                if (ifindex && dr.defrouter[i].if_index == ifindex) {
                        /* sanity check */
                        if (!IN6_IS_ADDR_LINKLOCAL(&dr.defrouter[i].rtaddr)) {
                                warnmsg(LOG_ERR, __func__,
                                        "default router list contains a "
                                        "non-linklocal address(%s)",
                                       inet_ntop(AF_INET6,
                                                 &dr.defrouter[i].rtaddr,
                                                 ntopbuf, INET6_ADDRSTRLEN));
                                continue; /* ignore the address */
                        }
                        sendprobe(&dr.defrouter[i].rtaddr,
                                  dr.defrouter[i].if_index);
                }
        }

  closeandend:
        close(s);
        return;
}

static void
sendprobe(struct in6_addr *addr, int ifindex)
{
        struct sockaddr_in6 sa6_probe;
        struct in6_pktinfo *pi;
        struct cmsghdr *cm;
        u_char ntopbuf[INET6_ADDRSTRLEN], ifnamebuf[IFNAMSIZ];

        bzero(&sa6_probe, sizeof(sa6_probe));
        sa6_probe.sin6_family = AF_INET6;
        sa6_probe.sin6_len = sizeof(sa6_probe);
        sa6_probe.sin6_addr = *addr;

        sndmhdr.msg_name = (caddr_t)&sa6_probe;
        sndmhdr.msg_iov[0].iov_base = NULL;
        sndmhdr.msg_iov[0].iov_len = 0;

        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 = ifindex;

        /* specify the hop limit of the packet for safety */
        {
                int hoplimit = 1;

                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__, "probe a router %s on %s",
               inet_ntop(AF_INET6, addr, ntopbuf, INET6_ADDRSTRLEN),
               if_indextoname(ifindex, ifnamebuf));

        if (sendmsg(probesock, &sndmhdr, 0))
                warnmsg(LOG_ERR, __func__, "sendmsg on %s: %s",
                        if_indextoname(ifindex, ifnamebuf), strerror(errno));

        return;
}