/*      $OpenBSD: control.c,v 1.16 2024/11/21 13:38:14 claudio Exp $ */

/*
 * 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/stat.h>
#include <sys/un.h>

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

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

TAILQ_HEAD(ctl_conns, ctl_conn) ctl_conns = TAILQ_HEAD_INITIALIZER(ctl_conns);

#define CONTROL_BACKLOG 5

static void              control_accept(int, short, void *);
static struct ctl_conn  *control_connbyfd(int);
static struct ctl_conn  *control_connbypid(pid_t);
static void              control_close(int);
static void              control_dispatch_imsg(int, short, void *);

struct {
        struct event    ev;
        struct event    evt;
        int             fd;
} control_state;


int
control_init(char *path)
{
        struct sockaddr_un       sun;
        int                      fd;
        mode_t                   old_umask;

        if ((fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
            0)) == -1) {
                log_warn("%s: socket", __func__);
                return (-1);
        }

        memset(&sun, 0, sizeof(sun));
        sun.sun_family = AF_UNIX;
        strlcpy(sun.sun_path, path, sizeof(sun.sun_path));

        if (unlink(path) == -1)
                if (errno != ENOENT) {
                        log_warn("%s: unlink %s", __func__, path);
                        close(fd);
                        return (-1);
                }

        old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
        if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
                log_warn("%s: bind: %s", __func__, path);
                close(fd);
                umask(old_umask);
                return (-1);
        }
        umask(old_umask);

        if (chmod(path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1) {
                log_warn("%s: chmod", __func__);
                close(fd);
                (void)unlink(path);
                return (-1);
        }

        control_state.fd = fd;

        return (0);
}

int
control_listen(void)
{
        if (listen(control_state.fd, CONTROL_BACKLOG) == -1) {
                log_warn("%s: listen", __func__);
                return (-1);
        }

        event_set(&control_state.ev, control_state.fd, EV_READ,
            control_accept, NULL);
        event_add(&control_state.ev, NULL);
        evtimer_set(&control_state.evt, control_accept, NULL);

        return (0);
}

static void
control_accept(int listenfd, short event, void *bula)
{
        int                      connfd;
        socklen_t                len;
        struct sockaddr_un       sun;
        struct ctl_conn         *c;

        event_add(&control_state.ev, NULL);
        if ((event & EV_TIMEOUT))
                return;

        len = sizeof(sun);
        if ((connfd = accept4(listenfd, (struct sockaddr *)&sun, &len,
            SOCK_CLOEXEC | SOCK_NONBLOCK)) == -1) {
                /*
                 * Pause accept if we are out of file descriptors, or
                 * libevent will haunt us here too.
                 */
                if (errno == ENFILE || errno == EMFILE) {
                        struct timeval evtpause = { 1, 0 };

                        event_del(&control_state.ev);
                        evtimer_add(&control_state.evt, &evtpause);
                } else if (errno != EWOULDBLOCK && errno != EINTR &&
                    errno != ECONNABORTED)
                        log_warn("%s: accept4", __func__);
                return;
        }

        if ((c = calloc(1, sizeof(struct ctl_conn))) == NULL) {
                log_warn("%s: calloc", __func__);
                close(connfd);
                return;
        }

        if (imsgbuf_init(&c->iev.ibuf, connfd) == -1) {
                log_warn("%s: imsgbuf_init", __func__);
                close(connfd);
                free(c);
                return;
        }
        c->iev.handler = control_dispatch_imsg;
        c->iev.events = EV_READ;
        event_set(&c->iev.ev, c->iev.ibuf.fd, c->iev.events,
            c->iev.handler, &c->iev);
        event_add(&c->iev.ev, NULL);

        TAILQ_INSERT_TAIL(&ctl_conns, c, entry);
}

static struct ctl_conn *
control_connbyfd(int fd)
{
        struct ctl_conn *c;

        TAILQ_FOREACH(c, &ctl_conns, entry) {
                if (c->iev.ibuf.fd == fd)
                        break;
        }

        return (c);
}

static struct ctl_conn *
control_connbypid(pid_t pid)
{
        struct ctl_conn *c;

        TAILQ_FOREACH(c, &ctl_conns, entry) {
                if (c->iev.ibuf.pid == pid)
                        break;
        }

        return (c);
}

static void
control_close(int fd)
{
        struct ctl_conn *c;

        if ((c = control_connbyfd(fd)) == NULL) {
                log_warnx("%s: fd %d: not found", __func__, fd);
                return;
        }

        imsgbuf_clear(&c->iev.ibuf);
        TAILQ_REMOVE(&ctl_conns, c, entry);

        event_del(&c->iev.ev);
        close(c->iev.ibuf.fd);

        /* Some file descriptors are available again. */
        if (evtimer_pending(&control_state.evt, NULL)) {
                evtimer_del(&control_state.evt);
                event_add(&control_state.ev, NULL);
        }

        free(c);
}

static void
control_dispatch_imsg(int fd, short event, void *bula)
{
        struct ctl_conn *c;
        struct imsg      imsg;
        ssize_t          n;
        unsigned int     ifidx;
        int              verbose;

        if ((c = control_connbyfd(fd)) == NULL) {
                log_warnx("%s: fd %d: not found", __func__, fd);
                return;
        }

        if (event & EV_READ) {
                if (imsgbuf_read(&c->iev.ibuf) != 1) {
                        control_close(fd);
                        return;
                }
        }
        if (event & EV_WRITE) {
                if (imsgbuf_write(&c->iev.ibuf) == -1) {
                        control_close(fd);
                        return;
                }
        }

        for (;;) {
                if ((n = imsg_get(&c->iev.ibuf, &imsg)) == -1) {
                        control_close(fd);
                        return;
                }

                if (n == 0)
                        break;

                switch (imsg.hdr.type) {
                case IMSG_CTL_FIB_COUPLE:
                case IMSG_CTL_FIB_DECOUPLE:
                case IMSG_CTL_RELOAD:
                        c->iev.ibuf.pid = imsg.hdr.pid;
                        eigrpe_imsg_compose_parent(imsg.hdr.type, 0, NULL, 0);
                        break;
                case IMSG_CTL_KROUTE:
                case IMSG_CTL_IFINFO:
                        c->iev.ibuf.pid = imsg.hdr.pid;
                        eigrpe_imsg_compose_parent(imsg.hdr.type, imsg.hdr.pid,
                            imsg.data, imsg.hdr.len - IMSG_HEADER_SIZE);
                        break;
                case IMSG_CTL_SHOW_INTERFACE:
                        if (imsg.hdr.len != IMSG_HEADER_SIZE +
                            sizeof(ifidx))
                                break;

                        memcpy(&ifidx, imsg.data, sizeof(ifidx));
                        eigrpe_iface_ctl(c, ifidx);
                        imsg_compose_event(&c->iev, IMSG_CTL_END, 0,
                            0, -1, NULL, 0);
                        break;
                case IMSG_CTL_SHOW_TOPOLOGY:
                        if (imsg.hdr.len != IMSG_HEADER_SIZE +
                            sizeof(struct ctl_show_topology_req))
                                break;

                        c->iev.ibuf.pid = imsg.hdr.pid;
                        eigrpe_imsg_compose_rde(imsg.hdr.type, 0, imsg.hdr.pid,
                            imsg.data, imsg.hdr.len - IMSG_HEADER_SIZE);
                        break;
                case IMSG_CTL_SHOW_NBR:
                        eigrpe_nbr_ctl(c);
                        break;
                case IMSG_CTL_SHOW_STATS:
                        eigrpe_stats_ctl(c);
                        break;
                case IMSG_CTL_CLEAR_NBR:
                        if (imsg.hdr.len != IMSG_HEADER_SIZE +
                            sizeof(struct ctl_nbr))
                                break;

                        nbr_clear_ctl(imsg.data);
                        break;
                case IMSG_CTL_LOG_VERBOSE:
                        if (imsg.hdr.len != IMSG_HEADER_SIZE +
                            sizeof(verbose))
                                break;

                        /* forward to other processes */
                        eigrpe_imsg_compose_parent(imsg.hdr.type, imsg.hdr.pid,
                            imsg.data, imsg.hdr.len - IMSG_HEADER_SIZE);
                        eigrpe_imsg_compose_rde(imsg.hdr.type, 0, imsg.hdr.pid,
                            imsg.data, imsg.hdr.len - IMSG_HEADER_SIZE);

                        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);
        }

        imsg_event_add(&c->iev);
}

int
control_imsg_relay(struct imsg *imsg)
{
        struct ctl_conn *c;

        if ((c = control_connbypid(imsg->hdr.pid)) == NULL)
                return (0);

        return (imsg_compose_event(&c->iev, imsg->hdr.type, 0, imsg->hdr.pid,
            -1, imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE));
}