/*      $OpenBSD: neighbor.c,v 1.12 2023/03/08 04:43:14 guenther Exp $ */

/*
 * Copyright (c) 2006 Michele Marchetto <mydecay@openbeer.it>
 * Copyright (c) 2005 Claudio Jeker <claudio@openbsd.org>
 * Copyright (c) 2004, 2005, 2006 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/ioctl.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>

#include <ctype.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <event.h>

#include "ripd.h"
#include "rip.h"
#include "ripe.h"
#include "log.h"
#include "rde.h"

void    nbr_set_timer(struct nbr *);
void    nbr_stop_timer(struct nbr *);

void    nbr_failed_new(struct nbr *);
void    nbr_failed_timeout(int, short, void *);

LIST_HEAD(nbr_head, nbr);

struct nbr_table {
        struct nbr_head         *hashtbl;
        u_int32_t                hashmask;
} nbrtable;

#define NBR_HASH(x)             \
        &nbrtable.hashtbl[(x) & nbrtable.hashmask]

u_int32_t       peercnt = NBR_CNTSTART;

struct {
        int             state;
        enum nbr_event  event;
        enum nbr_action action;
        int             new_state;
} nbr_fsm_tbl[] = {
    /* current state    event that happened     action to take          resulting state */
    {NBR_STA_DOWN,      NBR_EVT_REQUEST_RCVD,   NBR_ACT_NOTHING,        NBR_STA_REQ_RCVD},
    {NBR_STA_DOWN,      NBR_EVT_RESPONSE_RCVD,  NBR_ACT_STRT_TIMER,     NBR_STA_ACTIVE},
    {NBR_STA_ACTIVE,    NBR_EVT_RESPONSE_RCVD,  NBR_ACT_RST_TIMER,      NBR_STA_ACTIVE},
    {NBR_STA_ACTIVE,    NBR_EVT_REQUEST_RCVD,   NBR_ACT_NOTHING,        NBR_STA_ACTIVE},
    {NBR_STA_ACTIVE,    NBR_EVT_TIMEOUT,        NBR_ACT_DEL,            NBR_STA_DOWN},
    {NBR_STA_REQ_RCVD,  NBR_EVT_RESPONSE_SENT,  NBR_ACT_DEL,            NBR_STA_DOWN},
    {NBR_STA_ACTIVE,    NBR_EVT_RESPONSE_SENT,  NBR_ACT_NOTHING,        NBR_STA_ACTIVE},
    {NBR_STA_ANY,       NBR_EVT_KILL_NBR,       NBR_ACT_DEL,            NBR_STA_DOWN},
    {-1,                NBR_EVT_NOTHING,        NBR_ACT_NOTHING,        0},
};

const char * const nbr_event_names[] = {
        "RESPONSE RCVD",
        "REQUEST RCVD",
        "RESPONSE SENT",
        "NBR TIMEOUT",
        "NBR KILL",
        "NOTHING"
};

const char * const nbr_action_names[] = {
        "START TIMER",
        "RESET TIMER",
        "DELETE NBR",
        "NOTHING"
};

int
nbr_fsm(struct nbr *nbr, enum nbr_event event)
{
        struct timeval   now;
        int              old_state;
        int              new_state = 0;
        int              i;

        old_state = nbr->state;
        for (i = 0; nbr_fsm_tbl[i].state != -1; i++)
                if ((nbr_fsm_tbl[i].state & old_state) &&
                    (nbr_fsm_tbl[i].event == event)) {
                        new_state = nbr_fsm_tbl[i].new_state;
                        break;
                }

        if (nbr_fsm_tbl[i].state == -1) {
                /* event outside of the defined fsm, ignore it. */
                log_warnx("nbr_fsm: neighbor ID %s, "
                    "event '%s' not expected in state '%s'",
                    inet_ntoa(nbr->id), nbr_event_name(event),
                    nbr_state_name(old_state));
                return (0);
        }

        switch (nbr_fsm_tbl[i].action) {
        case NBR_ACT_RST_TIMER:
                nbr_set_timer(nbr);
                break;
        case NBR_ACT_STRT_TIMER:
                nbr_set_timer(nbr);
                break;
        case NBR_ACT_DEL:
                nbr_act_del(nbr);
                break;
        case NBR_ACT_NOTHING:
                /* do nothing */
                break;
        }

        if (new_state != 0)
                nbr->state = new_state;

        if (old_state != nbr->state) {
                /* neighbor changed from/to ACTIVE */
                gettimeofday(&now, NULL);
                nbr->uptime = now.tv_sec;

                log_debug("nbr_fsm: event '%s' resulted in action '%s' and "
                    "changing state for neighbor ID %s from '%s' to '%s'",
                    nbr_event_name(event),
                    nbr_action_name(nbr_fsm_tbl[i].action),
                    inet_ntoa(nbr->id), nbr_state_name(old_state),
                    nbr_state_name(nbr->state));
        }

        return (0);
}

void
nbr_init(u_int32_t hashsize)
{
        u_int32_t        hs, i;

        for (hs = 1; hs < hashsize; hs <<= 1)
                ;
        nbrtable.hashtbl = calloc(hs, sizeof(struct nbr_head));
        if (nbrtable.hashtbl == NULL)
                fatal("nbr_init");

        for (i = 0; i < hs; i++)
                LIST_INIT(&nbrtable.hashtbl[i]);

        nbrtable.hashmask = hs - 1;
}

struct nbr *
nbr_new(u_int32_t nbr_id, struct iface *iface)
{
        struct nbr_head *head;
        struct nbr      *nbr = NULL;

        if ((nbr = calloc(1, sizeof(*nbr))) == NULL)
                fatal("nbr_new");

        nbr->state = NBR_STA_DOWN;
        nbr->id.s_addr = nbr_id;

        /* get next unused peerid */
        while (nbr_find_peerid(++peercnt))
                ;
        nbr->peerid = peercnt;
        head = NBR_HASH(nbr->peerid);
        LIST_INSERT_HEAD(head, nbr, hash);

        /* add to peer list */
        nbr->iface = iface;
        LIST_INSERT_HEAD(&iface->nbr_list, nbr, entry);

        TAILQ_INIT(&nbr->rp_list);
        TAILQ_INIT(&nbr->rq_list);

        /* set event structures */
        evtimer_set(&nbr->timeout_timer, nbr_timeout_timer, nbr);

        log_debug("nbr_new: neighbor ID %s, peerid %u",
            inet_ntoa(nbr->id), nbr->peerid);

        return (nbr);
}

void
nbr_del(struct nbr *nbr)
{
        log_debug("nbr_del: neighbor ID %s, peerid %u", inet_ntoa(nbr->id),
            nbr->peerid);

        /* stop timer */
        nbr_stop_timer(nbr);

        LIST_REMOVE(nbr, entry);
        LIST_REMOVE(nbr, hash);

        free(nbr);
}

void
nbr_act_del(struct nbr *nbr)
{
        /* If there is no authentication or it is just a route request
         * there is no need to keep track of the failed neighbors */
        if (nbr->iface->auth_type == AUTH_CRYPT &&
            nbr->state != NBR_STA_REQ_RCVD)
                nbr_failed_new(nbr);

        log_debug("nbr_act_del: neighbor ID %s, peerid %u", inet_ntoa(nbr->id),
            nbr->peerid);

        /* schedule kill timer */
        nbr_set_timer(nbr);

        /* clear lists */
        clear_list(&nbr->rq_list);
        clear_list(&nbr->rp_list);
}

struct nbr *
nbr_find_peerid(u_int32_t peerid)
{
        struct nbr_head *head;
        struct nbr      *nbr;

        head = NBR_HASH(peerid);

        LIST_FOREACH(nbr, head, hash) {
                if (nbr->peerid == peerid)
                        return (nbr);
        }

        return (NULL);
}

struct nbr *
nbr_find_ip(struct iface *iface, u_int32_t src_ip)
{
        struct nbr      *nbr = NULL;

        LIST_FOREACH(nbr, &iface->nbr_list, entry) {
                if (nbr->id.s_addr == src_ip) {
                        return (nbr);
                }
        }

        return (NULL);
}

/* failed nbr handling */
void
nbr_failed_new(struct nbr *nbr)
{
        struct timeval           tv;
        struct iface            *iface;
        struct nbr_failed       *nbr_failed;

        if ((nbr_failed = calloc(1, sizeof(*nbr_failed))) == NULL)
                fatal("nbr_failed_new");

        nbr_failed->addr = nbr->addr;
        nbr_failed->auth_seq_num = nbr->auth_seq_num;
        iface = nbr->iface;

        timerclear(&tv);
        tv.tv_sec = FAILED_NBR_TIMEOUT;

        evtimer_set(&nbr_failed->timeout_timer, nbr_failed_timeout,
            nbr_failed);

        if (evtimer_add(&nbr_failed->timeout_timer, &tv) == -1)
                fatal("nbr_failed_new");

        LIST_INSERT_HEAD(&iface->failed_nbr_list, nbr_failed, entry);
}

struct nbr_failed *
nbr_failed_find(struct iface *iface, u_int32_t src_ip)
{
        struct nbr_failed       *nbr_failed = NULL;

        LIST_FOREACH(nbr_failed, &iface->failed_nbr_list, entry) {
                if (nbr_failed->addr.s_addr == src_ip) {
                        return (nbr_failed);
                }
        }

        return (NULL);
}

void
nbr_failed_delete(struct nbr_failed *nbr_failed)
{
        if (evtimer_pending(&nbr_failed->timeout_timer, NULL))
                if (evtimer_del(&nbr_failed->timeout_timer) == -1)
                        fatal("nbr_failed_delete");

        LIST_REMOVE(nbr_failed, entry);
        free(nbr_failed);
}

/* timers */
void
nbr_timeout_timer(int fd, short event, void *arg)
{
        struct nbr *nbr = arg;

        if (nbr->state == NBR_STA_DOWN)
                nbr_del(nbr);
        else
                nbr_fsm(nbr, NBR_EVT_TIMEOUT);
}

void
nbr_failed_timeout(int fd, short event, void *arg)
{
        struct nbr_failed       *nbr_failed = arg;

        log_debug("nbr_failed_timeout: failed neighbor ID %s deleted",
            inet_ntoa(nbr_failed->addr));

        nbr_failed_delete(nbr_failed);
}

/* actions */
void
nbr_set_timer(struct nbr *nbr)
{
        struct timeval  tv;

        timerclear(&tv);
        tv.tv_sec = NBR_TIMEOUT;

        if (evtimer_add(&nbr->timeout_timer, &tv) == -1)
                fatal("nbr_set_timer");
}

void
nbr_stop_timer(struct nbr *nbr)
{
        if (evtimer_del(&nbr->timeout_timer) == -1)
                fatal("nbr_stop_timer");
}

/* names */
const char *
nbr_event_name(int event)
{
        return (nbr_event_names[event]);
}

const char *
nbr_action_name(int action)
{
        return (nbr_action_names[action]);
}

struct ctl_nbr *
nbr_to_ctl(struct nbr *nbr)
{
        static struct ctl_nbr    nctl;
        struct timeval           tv, now, res;

        memcpy(nctl.name, nbr->iface->name, sizeof(nctl.name));
        memcpy(&nctl.id, &nbr->id, sizeof(nctl.id));
        memcpy(&nctl.addr, &nbr->addr, sizeof(nctl.addr));

        nctl.nbr_state = nbr->state;
        nctl.iface_state = nbr->iface->state;

        gettimeofday(&now, NULL);
        if (evtimer_pending(&nbr->timeout_timer, &tv)) {
                timersub(&tv, &now, &res);
                if (nbr->state & NBR_STA_DOWN)
                        nctl.dead_timer = NBR_TIMEOUT - res.tv_sec;
                else
                        nctl.dead_timer = res.tv_sec;
        } else
                nctl.dead_timer = 0;

        if (nbr->state == NBR_STA_ACTIVE) {
                nctl.uptime = now.tv_sec - nbr->uptime;
        } else
                nctl.uptime = 0;

        return (&nctl);
}