/*      $OpenBSD: hello.c,v 1.27 2024/08/21 15:18:00 florian Exp $ */

/*
 * Copyright (c) 2005 Claudio Jeker <claudio@openbsd.org>
 * Copyright (c) 2004, 2005 Esben Norby <norby@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/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <stdlib.h>
#include <string.h>
#include <event.h>

#include "ospfd.h"
#include "ospf.h"
#include "log.h"
#include "ospfe.h"

extern struct ospfd_conf        *oeconf;

/* hello packet handling */
int
send_hello(struct iface *iface)
{
        struct sockaddr_in       dst;
        struct hello_hdr         hello;
        struct nbr              *nbr;
        struct ibuf             *buf;

        dst.sin_family = AF_INET;
        dst.sin_len = sizeof(struct sockaddr_in);

        switch (iface->type) {
        case IF_TYPE_POINTOPOINT:
        case IF_TYPE_BROADCAST:
                inet_pton(AF_INET, AllSPFRouters, &dst.sin_addr);
                break;
        case IF_TYPE_NBMA:
        case IF_TYPE_POINTOMULTIPOINT:
                log_debug("send_hello: type %s not supported, interface %s",
                    if_type_name(iface->type), iface->name);
                return (-1);
        case IF_TYPE_VIRTUALLINK:
                dst.sin_addr = iface->dst;
                break;
        default:
                fatalx("send_hello: unknown interface type");
        }

        if ((buf = ibuf_dynamic(PKG_DEF_SIZE,
            IP_MAXPACKET - sizeof(struct ip))) == NULL)
                fatal("send_hello");

        /* OSPF header */
        if (gen_ospf_hdr(buf, iface, PACKET_TYPE_HELLO))
                goto fail;

        /* hello header */
        hello.mask = iface->mask.s_addr;
        hello.hello_interval = htons(iface->hello_interval);
        hello.opts = area_ospf_options(iface->area);
        hello.rtr_priority = iface->priority;
        hello.rtr_dead_interval = htonl(iface->dead_interval);

        if (iface->dr) {
                hello.d_rtr = iface->dr->addr.s_addr;
                iface->self->dr.s_addr = iface->dr->addr.s_addr;
        } else
                hello.d_rtr = 0;
        if (iface->bdr) {
                hello.bd_rtr = iface->bdr->addr.s_addr;
                iface->self->bdr.s_addr = iface->bdr->addr.s_addr;
        } else
                hello.bd_rtr = 0;

        if (ibuf_add(buf, &hello, sizeof(hello)))
                goto fail;

        /* active neighbor(s) */
        LIST_FOREACH(nbr, &iface->nbr_list, entry) {
                if ((nbr->state >= NBR_STA_INIT) && (nbr != iface->self))
                        if (ibuf_add(buf, &nbr->id, sizeof(nbr->id)))
                                goto fail;
        }

        /* update authentication and calculate checksum */
        if (auth_gen(buf, iface))
                goto fail;

        if (send_packet(iface, buf, &dst) == -1)
                goto fail;

        ibuf_free(buf);
        return (0);
fail:
        log_warn("%s", __func__);
        ibuf_free(buf);
        return (-1);
}

void
recv_hello(struct iface *iface, struct in_addr src, u_int32_t rtr_id, char *buf,
    u_int16_t len)
{
        struct hello_hdr         hello;
        struct nbr              *nbr = NULL, *dr;
        u_int32_t                nbr_id;
        int                      nbr_change = 0;

        if (len < sizeof(hello) || (len & 0x03)) {
                log_warnx("recv_hello: bad packet size, interface %s",
                    iface->name);
                return;
        }

        memcpy(&hello, buf, sizeof(hello));
        buf += sizeof(hello);
        len -= sizeof(hello);

        if (iface->type != IF_TYPE_POINTOPOINT &&
            iface->type != IF_TYPE_VIRTUALLINK)
                if (hello.mask != iface->mask.s_addr) {
                        log_warnx("recv_hello: invalid netmask, interface %s",
                            iface->name);
                        return;
                }

        if (ntohs(hello.hello_interval) != iface->hello_interval) {
                log_warnx("recv_hello: invalid hello-interval %d, "
                    "interface %s", ntohs(hello.hello_interval),
                    iface->name);
                return;
        }

        if (ntohl(hello.rtr_dead_interval) != iface->dead_interval) {
                log_warnx("recv_hello: invalid router-dead-interval %d, "
                    "interface %s", ntohl(hello.rtr_dead_interval),
                    iface->name);
                return;
        }

        if ((hello.opts & OSPF_OPTION_E && iface->area->stub) ||
            ((hello.opts & OSPF_OPTION_E) == 0 && !iface->area->stub)) {
                log_warnx("recv_hello: ExternalRoutingCapability mismatch, "
                    "interface %s", iface->name);
                return;
        }

        /*
         * Match router-id, in case of conflict moan and ignore hello.
         * Only the router-id is compared since the source IP on NBMA,
         * broadcast and point-to-multipoint interfaces was already
         * compared in find_iface() and only IPs in the same subnet
         * are accepted. This is not exactly what the RFC specifies
         * but works far better.
         */
        LIST_FOREACH(nbr, &iface->nbr_list, entry) {
                if (nbr == iface->self) {
                        if (nbr->id.s_addr == rtr_id) {
                                log_warnx("recv_hello: Router-ID collision on "
                                    "interface %s neighbor IP %s", iface->name,
                                    inet_ntoa(src));
                                return;
                        }
                        continue;
                }
                if (nbr->id.s_addr == rtr_id)
                        break;
        }

        if (!nbr) {
                nbr = nbr_new(rtr_id, iface, 0);
                /* set neighbor parameters */
                nbr->dr.s_addr = hello.d_rtr;
                nbr->bdr.s_addr = hello.bd_rtr;
                nbr->priority = hello.rtr_priority;
                /* XXX neighbor address shouldn't be stored on virtual links */
                nbr->addr.s_addr = src.s_addr;
                ospfe_imsg_compose_rde(IMSG_NEIGHBOR_ADDR, nbr->peerid, 0,
                    &src, sizeof(src));
        }

        if (nbr->addr.s_addr != src.s_addr) {
                log_warnx("%s: neighbor ID %s changed its IP address",
                    __func__, inet_ntoa(nbr->id));
                nbr->addr.s_addr = src.s_addr;
                ospfe_imsg_compose_rde(IMSG_NEIGHBOR_ADDR, nbr->peerid, 0,
                    &src, sizeof(src));
        }

        nbr->options = hello.opts;

        nbr_fsm(nbr, NBR_EVT_HELLO_RCVD);

        while (len >= sizeof(nbr_id)) {
                memcpy(&nbr_id, buf, sizeof(nbr_id));
                if (nbr_id == ospfe_router_id()) {
                        /* seen myself */
                        if (nbr->state & NBR_STA_PRELIM) {
                                nbr_fsm(nbr, NBR_EVT_2_WAY_RCVD);
                                nbr_change = 1;
                        }
                        break;
                }
                buf += sizeof(nbr_id);
                len -= sizeof(nbr_id);
        }

        if (len == 0) {
                nbr_fsm(nbr, NBR_EVT_1_WAY_RCVD);
                /* set neighbor parameters */
                nbr->dr.s_addr = hello.d_rtr;
                nbr->bdr.s_addr = hello.bd_rtr;
                nbr->priority = hello.rtr_priority;
                return;
        }

        if (nbr->priority != hello.rtr_priority) {
                nbr->priority = hello.rtr_priority;
                nbr_change = 1;
        }

        if (iface->state & IF_STA_WAITING &&
            hello.d_rtr == nbr->addr.s_addr && hello.bd_rtr == 0)
                if_fsm(iface, IF_EVT_BACKUP_SEEN);

        if (iface->state & IF_STA_WAITING && hello.bd_rtr == nbr->addr.s_addr) {
                /*
                 * In case we see the BDR make sure that the DR is around
                 * with a bidirectional (2_WAY or better) connection
                 */
                LIST_FOREACH(dr, &iface->nbr_list, entry)
                        if (hello.d_rtr == dr->addr.s_addr &&
                            dr->state & NBR_STA_BIDIR)
                                if_fsm(iface, IF_EVT_BACKUP_SEEN);
        }

        if ((nbr->addr.s_addr == nbr->dr.s_addr &&
            nbr->addr.s_addr != hello.d_rtr) ||
            (nbr->addr.s_addr != nbr->dr.s_addr &&
            nbr->addr.s_addr == hello.d_rtr))
                /* neighbor changed from or to DR */
                nbr_change = 1;
        if ((nbr->addr.s_addr == nbr->bdr.s_addr &&
            nbr->addr.s_addr != hello.bd_rtr) ||
            (nbr->addr.s_addr != nbr->bdr.s_addr &&
            nbr->addr.s_addr == hello.bd_rtr))
                /* neighbor changed from or to BDR */
                nbr_change = 1;

        nbr->dr.s_addr = hello.d_rtr;
        nbr->bdr.s_addr = hello.bd_rtr;

        if (nbr_change)
                if_fsm(iface, IF_EVT_NBR_CHNG);

        /* TODO NBMA needs some special handling */
}