/*      $OpenBSD: check_icmp.c,v 1.49 2026/03/02 19:28:01 rsadowski Exp $       */

/*
 * Copyright (c) 2006 Pierre-Yves Ritschard <pyr@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/time.h>

#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netinet/icmp6.h>
#include <arpa/inet.h>

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

#include "relayd.h"
#include "log.h"

void    icmp_setup(struct relayd *, struct ctl_icmp_event *, int);
void    check_icmp_add(struct ctl_icmp_event *, int, struct timeval *,
            void (*)(int, short, void *));
int     icmp_checks_done(struct ctl_icmp_event *);
void    icmp_checks_timeout(struct ctl_icmp_event *, enum host_error);
void    send_icmp(int, short, void *);
void    recv_icmp(int, short, void *);
int     in_cksum(u_short *, int);

void
icmp_setup(struct relayd *env, struct ctl_icmp_event *cie, int af)
{
        int proto = IPPROTO_ICMP, val;

        if (af == AF_INET6)
                proto = IPPROTO_ICMPV6;
        if ((cie->s = socket(af, SOCK_RAW | SOCK_NONBLOCK, proto)) == -1)
                fatal("%s: socket", __func__);
        val = ICMP_RCVBUF_SIZE;
        if (setsockopt(cie->s, SOL_SOCKET, SO_RCVBUF, &val, sizeof(val)) == -1)
                fatal("%s: setsockopt", __func__);
        cie->env = env;
        cie->af = af;
}

void
icmp_init(struct relayd *env)
{
        icmp_setup(env, &env->sc_icmp_send, AF_INET);
        icmp_setup(env, &env->sc_icmp_recv, AF_INET);
        icmp_setup(env, &env->sc_icmp6_send, AF_INET6);
        icmp_setup(env, &env->sc_icmp6_recv, AF_INET6);
        env->sc_id = getpid() & 0xffff;
}

void
schedule_icmp(struct relayd *env, struct host *host)
{
        host->last_up = host->up;
        host->flags &= ~(F_CHECK_SENT|F_CHECK_DONE);

        if (((struct sockaddr *)&host->conf.ss)->sa_family == AF_INET)
                env->sc_has_icmp = 1;
        else
                env->sc_has_icmp6 = 1;
}

void
check_icmp_add(struct ctl_icmp_event *cie, int flags, struct timeval *start,
    void (*fn)(int, short, void *))
{
        struct timeval   tv;

        if (start != NULL)
                bcopy(start, &cie->tv_start, sizeof(cie->tv_start));
        bcopy(&cie->env->sc_conf.timeout, &tv, sizeof(tv));
        getmonotime(&cie->tv_start);
        event_del(&cie->ev);
        event_set(&cie->ev, cie->s, EV_TIMEOUT|flags, fn, cie);
        event_add(&cie->ev, &tv);
}

void
check_icmp(struct relayd *env, struct timeval *tv)
{
        if (env->sc_has_icmp) {
                check_icmp_add(&env->sc_icmp_recv, EV_READ, tv, recv_icmp);
                check_icmp_add(&env->sc_icmp_send, EV_WRITE, tv, send_icmp);
        }
        if (env->sc_has_icmp6) {
                check_icmp_add(&env->sc_icmp6_recv, EV_READ, tv, recv_icmp);
                check_icmp_add(&env->sc_icmp6_send, EV_WRITE, tv, send_icmp);
        }
}

int
icmp_checks_done(struct ctl_icmp_event *cie)
{
        struct table    *table;
        struct host     *host;

        TAILQ_FOREACH(table, cie->env->sc_tables, entry) {
                if (table->conf.flags & F_DISABLE ||
                    table->conf.check != CHECK_ICMP)
                        continue;
                TAILQ_FOREACH(host, &table->hosts, entry) {
                        if (((struct sockaddr *)&host->conf.ss)->sa_family !=
                            cie->af)
                                continue;
                        if (!(host->flags & F_CHECK_DONE))
                                return (0);
                }
        }
        return (1);
}

void
icmp_checks_timeout(struct ctl_icmp_event *cie, enum host_error he)
{
        struct table    *table;
        struct host     *host;

        TAILQ_FOREACH(table, cie->env->sc_tables, entry) {
                if (table->conf.flags & F_DISABLE ||
                    table->conf.check != CHECK_ICMP)
                        continue;
                TAILQ_FOREACH(host, &table->hosts, entry) {
                        if (((struct sockaddr *)&host->conf.ss)->sa_family !=
                            cie->af)
                                continue;
                        if (!(host->flags & (F_CHECK_DONE|F_DISABLE))) {
                                host->up = HOST_DOWN;
                                hce_notify_done(host, he);
                        }
                }
        }
}

void
send_icmp(int s, short event, void *arg)
{
        struct ctl_icmp_event   *cie = arg;
        struct table            *table;
        struct host             *host;
        struct sockaddr         *to;
        struct icmp             *icp;
        struct icmp6_hdr        *icp6;
        ssize_t                  r;
        u_char                   packet[ICMP_BUF_SIZE];
        socklen_t                slen, len;
        int                      i = 0, ttl;
        u_int32_t                id;

        if (event == EV_TIMEOUT) {
                icmp_checks_timeout(cie, HCE_ICMP_WRITE_TIMEOUT);
                return;
        }

        bzero(&packet, sizeof(packet));
        icp = (struct icmp *)packet;
        icp6 = (struct icmp6_hdr *)packet;
        if (cie->af == AF_INET) {
                icp->icmp_type = ICMP_ECHO;
                icp->icmp_code = 0;
                icp->icmp_id = htons(cie->env->sc_id);
                icp->icmp_cksum = 0;
                slen = sizeof(struct sockaddr_in);
        } else {
                icp6->icmp6_type = ICMP6_ECHO_REQUEST;
                icp6->icmp6_code = 0;
                icp6->icmp6_cksum = 0;
                icp6->icmp6_id = htons(cie->env->sc_id);
                slen = sizeof(struct sockaddr_in6);
        }

        TAILQ_FOREACH(table, cie->env->sc_tables, entry) {
                if (table->conf.check != CHECK_ICMP ||
                    table->conf.flags & F_DISABLE)
                        continue;
                TAILQ_FOREACH(host, &table->hosts, entry) {
                        if (host->flags & (F_DISABLE | F_CHECK_SENT) ||
                            host->conf.parentid)
                                continue;
                        if (((struct sockaddr *)&host->conf.ss)->sa_family !=
                            cie->af)
                                continue;
                        i++;
                        to = (struct sockaddr *)&host->conf.ss;
                        id = htonl(host->conf.id);

                        if (cie->af == AF_INET) {
                                icp->icmp_seq = htons(i);
                                icp->icmp_cksum = 0;
                                icp->icmp_mask = id;
                                icp->icmp_cksum = in_cksum((u_short *)icp,
                                    sizeof(packet));
                        } else {
                                icp6->icmp6_seq = htons(i);
                                icp6->icmp6_cksum = 0;
                                memcpy(packet + sizeof(*icp6), &id, sizeof(id));
                                icp6->icmp6_cksum = in_cksum((u_short *)icp6,
                                    sizeof(packet));
                        }

                        ttl = host->conf.ttl;
                        switch(cie->af) {
                        case AF_INET:
                                if (ttl > 0) {
                                        if (setsockopt(s, IPPROTO_IP, IP_TTL,
                                            &ttl, sizeof(ttl)) == -1)
                                                log_warn("%s: setsockopt",
                                                    __func__);
                                } else {
                                        /* Revert to default TTL */
                                        len = sizeof(ttl);
                                        if (getsockopt(s, IPPROTO_IP,
                                            IP_IPDEFTTL, &ttl, &len) == 0) {
                                                if (setsockopt(s, IPPROTO_IP,
                                                    IP_TTL, &ttl, len) == -1)
                                                        log_warn(
                                                            "%s: setsockopt",
                                                            __func__);
                                        } else
                                                log_warn("%s: getsockopt",
                                                    __func__);
                                }
                                break;
                        case AF_INET6:
                                if (ttl > 0) {
                                        if (setsockopt(s, IPPROTO_IPV6,
                                            IPV6_UNICAST_HOPS, &ttl,
                                            sizeof(ttl)) == -1)
                                                log_warn("%s: setsockopt",
                                                    __func__);
                                } else {
                                        /* Revert to default hop limit */
                                        ttl = -1;
                                        if (setsockopt(s, IPPROTO_IPV6,
                                            IPV6_UNICAST_HOPS, &ttl,
                                            sizeof(ttl)) == -1)
                                                log_warn("%s: setsockopt",
                                                    __func__);
                                }
                                break;
                        }

                        r = sendto(s, packet, sizeof(packet), 0, to, slen);
                        if (r == -1) {
                                if (errno == EAGAIN || errno == EINTR)
                                        goto retry;
                                host->flags |= F_CHECK_SENT|F_CHECK_DONE;
                                host->up = HOST_DOWN;
                        } else if (r != sizeof(packet))
                                goto retry;
                        host->flags |= F_CHECK_SENT;
                }
        }

        return;

 retry:
        event_again(&cie->ev, s, EV_TIMEOUT|EV_WRITE, send_icmp,
            &cie->tv_start, &cie->env->sc_conf.timeout, cie);
}

void
recv_icmp(int s, short event, void *arg)
{
        struct ctl_icmp_event   *cie = arg;
        u_char                   packet[ICMP_BUF_SIZE];
        socklen_t                slen;
        struct sockaddr_storage  ss;
        struct icmp             *icp;
        struct icmp6_hdr        *icp6;
        u_int16_t                icpid;
        struct host             *host;
        ssize_t                  r;
        u_int32_t                id;

        if (event == EV_TIMEOUT) {
                icmp_checks_timeout(cie, HCE_ICMP_READ_TIMEOUT);
                return;
        }

        bzero(&packet, sizeof(packet));
        bzero(&ss, sizeof(ss));
        slen = sizeof(ss);

        r = recvfrom(s, packet, sizeof(packet), 0,
            (struct sockaddr *)&ss, &slen);
        if (r == -1 || r != ICMP_BUF_SIZE) {
                if (r == -1 && errno != EAGAIN && errno != EINTR)
                        log_debug("%s: receive error", __func__);
                goto retry;
        }

        if (cie->af == AF_INET) {
                icp = (struct icmp *)(packet + sizeof(struct ip));
                icpid = ntohs(icp->icmp_id);
                id = icp->icmp_mask;
        } else {
                icp6 = (struct icmp6_hdr *)packet;
                icpid = ntohs(icp6->icmp6_id);
                memcpy(&id, packet + sizeof(*icp6), sizeof(id));
        }
        if (icpid != cie->env->sc_id)
                goto retry;
        id = ntohl(id);
        host = host_find(cie->env, id);
        if (host == NULL) {
                log_warn("%s: ping for unknown host received", __func__);
                goto retry;
        }
        if (bcmp(&ss, &host->conf.ss, slen)) {
                log_warnx("%s: forged icmp packet?", __func__);
                goto retry;
        }

        host->up = HOST_UP;
        host->flags |= F_CHECK_DONE;
        hce_notify_done(host, HCE_ICMP_OK);

        if (icmp_checks_done(cie))
                return;

 retry:
        event_again(&cie->ev, s, EV_TIMEOUT|EV_READ, recv_icmp,
            &cie->tv_start, &cie->env->sc_conf.timeout, cie);
}

/* in_cksum from ping.c --
 *      Checksum routine for Internet Protocol family headers (C Version)
 *
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Muuss.
 *
 * 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 University 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 REGENTS 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 REGENTS 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.
 */
int
in_cksum(u_short *addr, int len)
{
        int nleft = len;
        u_short *w = addr;
        int sum = 0;
        u_short answer = 0;

        /*
         * Our algorithm is simple, using a 32 bit accumulator (sum), we add
         * sequential 16 bit words to it, and at the end, fold back all the
         * carry bits from the top 16 bits into the lower 16 bits.
         */
        while (nleft > 1)  {
                sum += *w++;
                nleft -= 2;
        }

        /* mop up an odd byte, if necessary */
        if (nleft == 1) {
                *(u_char *)(&answer) = *(u_char *)w ;
                sum += answer;
        }

        /* add back carry outs from top 16 bits to low 16 bits */
        sum = (sum >> 16) + (sum & 0xffff);     /* add hi 16 to low 16 */
        sum += (sum >> 16);                     /* add carry */
        answer = ~sum;                          /* truncate to 16 bits */

        return (answer);
}