/*      $OpenBSD: eigrpd.c,v 1.36 2024/11/21 13:38:14 claudio Exp $ */

/*
 * Copyright (c) 2015 Renato Westphal <renato@openbsd.org>
 * Copyright (c) 2005 Claudio Jeker <claudio@openbsd.org>
 * Copyright (c) 2004 Esben Norby <norby@openbsd.org>
 * Copyright (c) 2003, 2004 Henning Brauer <henning@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/wait.h>
#include <sys/sysctl.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "eigrpd.h"
#include "eigrpe.h"
#include "rde.h"
#include "log.h"

static void              main_sig_handler(int, short, void *);
static __dead void       usage(void);
static __dead void       eigrpd_shutdown(void);
static pid_t             start_child(enum eigrpd_process, char *, int, int, int,
                            char *);
static void              main_dispatch_eigrpe(int, short, void *);
static void              main_dispatch_rde(int, short, void *);
static int               main_imsg_send_ipc_sockets(struct imsgbuf *,
                            struct imsgbuf *);
static int               main_imsg_send_config(struct eigrpd_conf *);
static int               eigrp_reload(void);
static int               eigrp_sendboth(enum imsg_type, void *, uint16_t);
static void              merge_instances(struct eigrpd_conf *, struct eigrp *,
                            struct eigrp *);

struct eigrpd_conf      *eigrpd_conf;

static char             *conffile;
static struct imsgev    *iev_eigrpe;
static struct imsgev    *iev_rde;
static pid_t             eigrpe_pid;
static pid_t             rde_pid;

static void
main_sig_handler(int sig, short event, void *arg)
{
        /* signal handler rules don't apply, libevent decouples for us */
        switch (sig) {
        case SIGTERM:
        case SIGINT:
                eigrpd_shutdown();
                /* NOTREACHED */
        case SIGHUP:
                if (eigrp_reload() == -1)
                        log_warnx("configuration reload failed");
                else
                        log_debug("configuration reloaded");
                break;
        default:
                fatalx("unexpected signal");
                /* NOTREACHED */
        }
}

static __dead void
usage(void)
{
        extern char *__progname;

        fprintf(stderr, "usage: %s [-dnv] [-D macro=value]"
            " [-f file] [-s socket]\n",
            __progname);
        exit(1);
}

struct eigrpd_global global;

int
main(int argc, char *argv[])
{
        struct event             ev_sigint, ev_sigterm, ev_sighup;
        char                    *saved_argv0;
        int                      ch;
        int                      debug = 0, rflag = 0, eflag = 0;
        int                      ipforwarding;
        int                      mib[4];
        size_t                   len;
        char                    *sockname;
        int                      pipe_parent2eigrpe[2];
        int                      pipe_parent2rde[2];

        conffile = CONF_FILE;
        log_procname = "parent";
        sockname = EIGRPD_SOCKET;

        log_init(1);    /* log to stderr until daemonized */
        log_verbose(1);

        saved_argv0 = argv[0];
        if (saved_argv0 == NULL)
                saved_argv0 = "eigrpd";

        while ((ch = getopt(argc, argv, "dD:f:ns:vRE")) != -1) {
                switch (ch) {
                case 'd':
                        debug = 1;
                        break;
                case 'D':
                        if (cmdline_symset(optarg) < 0)
                                log_warnx("could not parse macro definition %s",
                                    optarg);
                        break;
                case 'f':
                        conffile = optarg;
                        break;
                case 'n':
                        global.cmd_opts |= EIGRPD_OPT_NOACTION;
                        break;
                case 's':
                        sockname = optarg;
                        break;
                case 'v':
                        if (global.cmd_opts & EIGRPD_OPT_VERBOSE)
                                global.cmd_opts |= EIGRPD_OPT_VERBOSE2;
                        global.cmd_opts |= EIGRPD_OPT_VERBOSE;
                        break;
                case 'R':
                        rflag = 1;
                        break;
                case 'E':
                        eflag = 1;
                        break;
                default:
                        usage();
                        /* NOTREACHED */
                }
        }

        argc -= optind;
        argv += optind;
        if (argc > 0 || (rflag && eflag))
                usage();

        if (rflag)
                rde(debug, global.cmd_opts & EIGRPD_OPT_VERBOSE);
        else if (eflag)
                eigrpe(debug, global.cmd_opts & EIGRPD_OPT_VERBOSE, sockname);

        mib[0] = CTL_NET;
        mib[1] = PF_INET;
        mib[2] = IPPROTO_IP;
        mib[3] = IPCTL_FORWARDING;
        len = sizeof(ipforwarding);
        if (sysctl(mib, 4, &ipforwarding, &len, NULL, 0) == -1)
                log_warn("sysctl");

        if (ipforwarding != 1)
                log_warnx("WARNING: IP forwarding NOT enabled");

        /* fetch interfaces early */
        kif_init();

        /* parse config file */
        if ((eigrpd_conf = parse_config(conffile)) == NULL) {
                kif_clear();
                exit(1);
        }

        if (global.cmd_opts & EIGRPD_OPT_NOACTION) {
                if (global.cmd_opts & EIGRPD_OPT_VERBOSE)
                        print_config(eigrpd_conf);
                else
                        fprintf(stderr, "configuration OK\n");
                kif_clear();
                exit(0);
        }

        /* check for root privileges  */
        if (geteuid())
                errx(1, "need root privileges");

        /* check for eigrpd user */
        if (getpwnam(EIGRPD_USER) == NULL)
                errx(1, "unknown user %s", EIGRPD_USER);

        log_init(debug);
        log_verbose(global.cmd_opts & EIGRPD_OPT_VERBOSE);

        if (!debug)
                daemon(1, 0);

        log_info("startup");

        if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
            PF_UNSPEC, pipe_parent2eigrpe) == -1)
                fatal("socketpair");
        if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
            PF_UNSPEC, pipe_parent2rde) == -1)
                fatal("socketpair");

        /* start children */
        rde_pid = start_child(PROC_RDE_ENGINE, saved_argv0, pipe_parent2rde[1],
            debug, global.cmd_opts & EIGRPD_OPT_VERBOSE, NULL);
        eigrpe_pid = start_child(PROC_EIGRP_ENGINE, saved_argv0,
            pipe_parent2eigrpe[1], debug, global.cmd_opts & EIGRPD_OPT_VERBOSE,
            sockname);

        event_init();

        /* setup signal handler */
        signal_set(&ev_sigint, SIGINT, main_sig_handler, NULL);
        signal_set(&ev_sigterm, SIGTERM, main_sig_handler, NULL);
        signal_set(&ev_sighup, SIGHUP, main_sig_handler, NULL);
        signal_add(&ev_sigint, NULL);
        signal_add(&ev_sigterm, NULL);
        signal_add(&ev_sighup, NULL);
        signal(SIGPIPE, SIG_IGN);

        /* setup pipes to children */
        if ((iev_eigrpe = malloc(sizeof(struct imsgev))) == NULL ||
            (iev_rde = malloc(sizeof(struct imsgev))) == NULL)
                fatal(NULL);
        if (imsgbuf_init(&iev_eigrpe->ibuf, pipe_parent2eigrpe[0]) == -1)
                fatal(NULL);
        imsgbuf_allow_fdpass(&iev_eigrpe->ibuf);
        iev_eigrpe->handler = main_dispatch_eigrpe;
        if (imsgbuf_init(&iev_rde->ibuf, pipe_parent2rde[0]) == -1)
                fatal(NULL);
        imsgbuf_allow_fdpass(&iev_rde->ibuf);
        iev_rde->handler = main_dispatch_rde;

        /* setup event handler */
        iev_eigrpe->events = EV_READ;
        event_set(&iev_eigrpe->ev, iev_eigrpe->ibuf.fd, iev_eigrpe->events,
            iev_eigrpe->handler, iev_eigrpe);
        event_add(&iev_eigrpe->ev, NULL);

        iev_rde->events = EV_READ;
        event_set(&iev_rde->ev, iev_rde->ibuf.fd, iev_rde->events,
            iev_rde->handler, iev_rde);
        event_add(&iev_rde->ev, NULL);

        if (main_imsg_send_ipc_sockets(&iev_eigrpe->ibuf, &iev_rde->ibuf))
                fatal("could not establish imsg links");
        main_imsg_send_config(eigrpd_conf);

        /* notify eigrpe about existing interfaces and addresses */
        kif_redistribute();

        if (kr_init(!(eigrpd_conf->flags & EIGRPD_FLAG_NO_FIB_UPDATE),
            eigrpd_conf->rdomain) == -1)
                fatalx("kr_init failed");

        if (pledge("stdio rpath inet sendfd", NULL) == -1)
                fatal("pledge");

        event_dispatch();

        eigrpd_shutdown();
        /* NOTREACHED */
        return (0);
}

static __dead void
eigrpd_shutdown(void)
{
        pid_t            pid;
        int              status;

        /* close pipes */
        imsgbuf_clear(&iev_eigrpe->ibuf);
        close(iev_eigrpe->ibuf.fd);
        imsgbuf_clear(&iev_rde->ibuf);
        close(iev_rde->ibuf.fd);

        kr_shutdown();
        config_clear(eigrpd_conf, PROC_MAIN);

        log_debug("waiting for children to terminate");
        do {
                pid = wait(&status);
                if (pid == -1) {
                        if (errno != EINTR && errno != ECHILD)
                                fatal("wait");
                } else if (WIFSIGNALED(status))
                        log_warnx("%s terminated; signal %d",
                            (pid == rde_pid) ? "route decision engine" :
                            "eigrp engine", WTERMSIG(status));
        } while (pid != -1 || (pid == -1 && errno == EINTR));

        free(iev_eigrpe);
        free(iev_rde);

        log_info("terminating");
        exit(0);
}

static pid_t
start_child(enum eigrpd_process p, char *argv0, int fd, int debug, int verbose,
    char *sockname)
{
        char    *argv[7];
        int      argc = 0;
        pid_t    pid;

        switch (pid = fork()) {
        case -1:
                fatal("cannot fork");
        case 0:
                break;
        default:
                close(fd);
                return (pid);
        }

        if (fd != 3) {
                if (dup2(fd, 3) == -1)
                        fatal("cannot setup imsg fd");
        } else if (fcntl(fd, F_SETFD, 0) == -1)
                fatal("cannot setup imsg fd");

        argv[argc++] = argv0;
        switch (p) {
        case PROC_MAIN:
                fatalx("Can not start main process");
        case PROC_RDE_ENGINE:
                argv[argc++] = "-R";
                break;
        case PROC_EIGRP_ENGINE:
                argv[argc++] = "-E";
                break;
        }
        if (debug)
                argv[argc++] = "-d";
        if (verbose)
                argv[argc++] = "-v";
        if (sockname) {
                argv[argc++] = "-s";
                argv[argc++] = sockname;
        }
        argv[argc++] = NULL;

        execvp(argv0, argv);
        fatal("execvp");
}

/* imsg handling */
static void
main_dispatch_eigrpe(int fd, short event, void *bula)
{
        struct imsgev           *iev = bula;
        struct imsgbuf          *ibuf;
        struct imsg              imsg;
        ssize_t                  n;
        int                      shut = 0, verbose;

        ibuf = &iev->ibuf;

        if (event & EV_READ) {
                if ((n = imsgbuf_read(ibuf)) == -1)
                        fatal("imsgbuf_read error");
                if (n == 0)     /* connection closed */
                        shut = 1;
        }
        if (event & EV_WRITE) {
                if (imsgbuf_write(ibuf) == -1) {
                        if (errno == EPIPE)     /* connection closed */
                                shut = 1;
                        else
                                fatal("imsgbuf_write");
                }
        }

        for (;;) {
                if ((n = imsg_get(ibuf, &imsg)) == -1)
                        fatal("imsg_get");

                if (n == 0)
                        break;

                switch (imsg.hdr.type) {
                case IMSG_CTL_RELOAD:
                        if (eigrp_reload() == -1)
                                log_warnx("configuration reload failed");
                        else
                                log_debug("configuration reloaded");
                        break;
                case IMSG_CTL_FIB_COUPLE:
                        kr_fib_couple();
                        break;
                case IMSG_CTL_FIB_DECOUPLE:
                        kr_fib_decouple();
                        break;
                case IMSG_CTL_KROUTE:
                        kr_show_route(&imsg);
                        break;
                case IMSG_CTL_IFINFO:
                        if (imsg.hdr.len == IMSG_HEADER_SIZE)
                                kr_ifinfo(NULL, imsg.hdr.pid);
                        else if (imsg.hdr.len == IMSG_HEADER_SIZE + IFNAMSIZ)
                                kr_ifinfo(imsg.data, imsg.hdr.pid);
                        else
                                log_warnx("IFINFO request with wrong len");
                        break;
                case IMSG_CTL_LOG_VERBOSE:
                        /* already checked by eigrpe */
                        memcpy(&verbose, imsg.data, sizeof(verbose));
                        log_verbose(verbose);
                        break;
                default:
                        log_debug("%s: error handling imsg %d", __func__,
                            imsg.hdr.type);
                        break;
                }
                imsg_free(&imsg);
        }
        if (!shut)
                imsg_event_add(iev);
        else {
                /* this pipe is dead, so remove the event handler */
                event_del(&iev->ev);
                event_loopexit(NULL);
        }
}

static void
main_dispatch_rde(int fd, short event, void *bula)
{
        struct imsgev   *iev = bula;
        struct imsgbuf  *ibuf;
        struct imsg      imsg;
        ssize_t          n;
        int              shut = 0;

        ibuf = &iev->ibuf;

        if (event & EV_READ) {
                if ((n = imsgbuf_read(ibuf)) == -1)
                        fatal("imsgbuf_read error");
                if (n == 0)     /* connection closed */
                        shut = 1;
        }
        if (event & EV_WRITE) {
                if (imsgbuf_write(ibuf) == -1) {
                        if (errno == EPIPE)     /* connection closed */
                                shut = 1;
                        else
                                fatal("imsgbuf_write");
                }
        }

        for (;;) {
                if ((n = imsg_get(ibuf, &imsg)) == -1)
                        fatal("imsg_get");

                if (n == 0)
                        break;

                switch (imsg.hdr.type) {
                case IMSG_KROUTE_CHANGE:
                        if (imsg.hdr.len - IMSG_HEADER_SIZE !=
                            sizeof(struct kroute))
                                fatalx("invalid size of IMSG_KROUTE_CHANGE");
                        if (kr_change(imsg.data))
                                log_warnx("%s: error changing route", __func__);
                        break;
                case IMSG_KROUTE_DELETE:
                        if (imsg.hdr.len - IMSG_HEADER_SIZE !=
                            sizeof(struct kroute))
                                fatalx("invalid size of IMSG_KROUTE_DELETE");
                        if (kr_delete(imsg.data))
                                log_warnx("%s: error deleting route", __func__);
                        break;

                default:
                        log_debug("%s: error handling imsg %d", __func__,
                            imsg.hdr.type);
                        break;
                }
                imsg_free(&imsg);
        }
        if (!shut)
                imsg_event_add(iev);
        else {
                /* this pipe is dead, so remove the event handler */
                event_del(&iev->ev);
                event_loopexit(NULL);
        }
}

int
main_imsg_compose_eigrpe(int type, pid_t pid, void *data, uint16_t datalen)
{
        if (iev_eigrpe == NULL)
                return (-1);
        return (imsg_compose_event(iev_eigrpe, type, 0, pid, -1, data, datalen));
}

int
main_imsg_compose_rde(int type, pid_t pid, void *data, uint16_t datalen)
{
        if (iev_rde == NULL)
                return (-1);
        return (imsg_compose_event(iev_rde, type, 0, pid, -1, data, datalen));
}

void
imsg_event_add(struct imsgev *iev)
{
        iev->events = EV_READ;
        if (imsgbuf_queuelen(&iev->ibuf) > 0)
                iev->events |= EV_WRITE;

        event_del(&iev->ev);
        event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev);
        event_add(&iev->ev, NULL);
}

int
imsg_compose_event(struct imsgev *iev, uint16_t type, uint32_t peerid,
    pid_t pid, int fd, void *data, uint16_t datalen)
{
        int     ret;

        if ((ret = imsg_compose(&iev->ibuf, type, peerid,
            pid, fd, data, datalen)) != -1)
                imsg_event_add(iev);
        return (ret);
}

static int
main_imsg_send_ipc_sockets(struct imsgbuf *eigrpe_buf, struct imsgbuf *rde_buf)
{
        int pipe_eigrpe2rde[2];

        if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
            PF_UNSPEC, pipe_eigrpe2rde) == -1)
                return (-1);

        if (imsg_compose(eigrpe_buf, IMSG_SOCKET_IPC, 0, 0, pipe_eigrpe2rde[0],
            NULL, 0) == -1)
                return (-1);
        if (imsg_compose(rde_buf, IMSG_SOCKET_IPC, 0, 0, pipe_eigrpe2rde[1],
            NULL, 0) == -1)
                return (-1);

        return (0);
}

struct eigrp *
eigrp_find(struct eigrpd_conf *xconf, int af, uint16_t as)
{
        struct eigrp    *eigrp;

        TAILQ_FOREACH(eigrp, &xconf->instances, entry)
                if (eigrp->af == af && eigrp->as == as)
                        return (eigrp);

        return (NULL);
}

static int
main_imsg_send_config(struct eigrpd_conf *xconf)
{
        struct eigrp            *eigrp;
        struct eigrp_iface      *ei;

        if (eigrp_sendboth(IMSG_RECONF_CONF, xconf, sizeof(*xconf)) == -1)
                return (-1);

        TAILQ_FOREACH(eigrp, &xconf->instances, entry) {
                if (eigrp_sendboth(IMSG_RECONF_INSTANCE, eigrp,
                    sizeof(*eigrp)) == -1)
                        return (-1);

                TAILQ_FOREACH(ei, &eigrp->ei_list, e_entry) {
                        if (eigrp_sendboth(IMSG_RECONF_IFACE, ei->iface,
                            sizeof(struct iface)) == -1)
                                return (-1);

                        if (eigrp_sendboth(IMSG_RECONF_EIGRP_IFACE, ei,
                            sizeof(*ei)) == -1)
                                return (-1);
                }
        }

        if (eigrp_sendboth(IMSG_RECONF_END, NULL, 0) == -1)
                return (-1);

        return (0);
}

static int
eigrp_reload(void)
{
        struct eigrpd_conf      *xconf;

        if ((xconf = parse_config(conffile)) == NULL)
                return (-1);

        if (main_imsg_send_config(xconf) == -1)
                return (-1);

        merge_config(eigrpd_conf, xconf, PROC_MAIN);

        return (0);
}

static int
eigrp_sendboth(enum imsg_type type, void *buf, uint16_t len)
{
        if (main_imsg_compose_eigrpe(type, 0, buf, len) == -1)
                return (-1);
        if (main_imsg_compose_rde(type, 0, buf, len) == -1)
                return (-1);
        return (0);
}

void
merge_config(struct eigrpd_conf *conf, struct eigrpd_conf *xconf,
    enum eigrpd_process proc)
{
        struct iface            *iface, *itmp, *xi;
        struct eigrp            *eigrp, *etmp, *xe;

        conf->rtr_id = xconf->rtr_id;
        conf->flags = xconf->flags;
        conf->rdomain= xconf->rdomain;
        conf->fib_priority_internal = xconf->fib_priority_internal;
        conf->fib_priority_external = xconf->fib_priority_external;
        conf->fib_priority_summary = xconf->fib_priority_summary;

        /* merge instances */
        TAILQ_FOREACH_SAFE(eigrp, &conf->instances, entry, etmp) {
                /* find deleted instances */
                if ((xe = eigrp_find(xconf, eigrp->af, eigrp->as)) == NULL) {
                        TAILQ_REMOVE(&conf->instances, eigrp, entry);

                        switch (proc) {
                        case PROC_RDE_ENGINE:
                                rde_instance_del(eigrp);
                                break;
                        case PROC_EIGRP_ENGINE:
                                eigrpe_instance_del(eigrp);
                                break;
                        case PROC_MAIN:
                                free(eigrp);
                                break;
                        }
                }
        }
        TAILQ_FOREACH_SAFE(xe, &xconf->instances, entry, etmp) {
                /* find new instances */
                if ((eigrp = eigrp_find(conf, xe->af, xe->as)) == NULL) {
                        TAILQ_REMOVE(&xconf->instances, xe, entry);
                        TAILQ_INSERT_TAIL(&conf->instances, xe, entry);

                        switch (proc) {
                        case PROC_RDE_ENGINE:
                                rde_instance_init(xe);
                                break;
                        case PROC_EIGRP_ENGINE:
                                eigrpe_instance_init(xe);
                                break;
                        case PROC_MAIN:
                                break;
                        }
                        continue;
                }

                /* update existing instances */
                merge_instances(conf, eigrp, xe);
        }

        /* merge interfaces */
        TAILQ_FOREACH_SAFE(iface, &conf->iface_list, entry, itmp) {
                /* find deleted ifaces */
                if ((xi = if_lookup(xconf, iface->ifindex)) == NULL) {
                        TAILQ_REMOVE(&conf->iface_list, iface, entry);
                        free(iface);
                }
        }
        TAILQ_FOREACH_SAFE(xi, &xconf->iface_list, entry, itmp) {
                /* find new ifaces */
                if ((iface = if_lookup(conf, xi->ifindex)) == NULL) {
                        TAILQ_REMOVE(&xconf->iface_list, xi, entry);
                        TAILQ_INSERT_TAIL(&conf->iface_list, xi, entry);
                        continue;
                }

                /* TODO update existing ifaces */
        }       

        /* resend addresses to activate new interfaces */
        if (proc == PROC_MAIN)
                kif_redistribute();

        free(xconf);
}

static void
merge_instances(struct eigrpd_conf *xconf, struct eigrp *eigrp, struct eigrp *xe)
{
        /* TODO */
}

struct eigrpd_conf *
config_new_empty(void)
{
        struct eigrpd_conf      *xconf;

        xconf = calloc(1, sizeof(*xconf));
        if (xconf == NULL)
                fatal(NULL);

        TAILQ_INIT(&xconf->instances);
        TAILQ_INIT(&xconf->iface_list);

        return (xconf);
}

void
config_clear(struct eigrpd_conf *conf, enum eigrpd_process proc)
{
        struct eigrpd_conf      *xconf;

        /* merge current config with an empty config */
        xconf = config_new_empty();
        merge_config(conf, xconf, proc);

        free(conf);
}