/*      $OpenBSD: control.c,v 1.16 2025/03/25 03:07:58 yasuoka 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/queue.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <netinet/in.h>

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

#include <imsg.h>

#include "log.h"

#define CONTROL_BACKLOG 5

#include "npppd_local.h"
#include "npppd_ctl.h"

struct ctl_conn_list ctl_conns;

struct ctl_conn *control_connbyfd(int);
void             control_close(int, struct control_sock *);
void             control_accept (int, short, void *);
void             control_close (int, struct control_sock *);
void             control_dispatch_imsg (int, short, void *);
void             control_imsg_forward (struct imsg *);

int
control_init(struct control_sock *cs)
{
        struct sockaddr_un       sun;
        int                      fd;
        mode_t                   old_umask, mode;

        if (cs->cs_name == NULL)
                return (0);

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

        sun.sun_family = AF_UNIX;
        if (strlcpy(sun.sun_path, cs->cs_name,
            sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
                log_warn("control_init: %s name too long", cs->cs_name);
                close(fd);
                return (-1);
        }

        if (unlink(cs->cs_name) == -1)
                if (errno != ENOENT) {
                        log_warn("control_init: unlink %s", cs->cs_name);
                        close(fd);
                        return (-1);
                }

        if (cs->cs_restricted) {
                old_umask = umask(S_IXUSR|S_IXGRP|S_IXOTH);
                mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
        } else {
                old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
                mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP;
        }

        if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
                log_warn("control_init: bind: %s", cs->cs_name);
                close(fd);
                (void)umask(old_umask);
                return (-1);
        }
        (void)umask(old_umask);

        if (chmod(cs->cs_name, mode) == -1) {
                log_warn("control_init: chmod");
                close(fd);
                (void)unlink(cs->cs_name);
                return (-1);
        }
        TAILQ_INIT(&ctl_conns);

        cs->cs_fd = fd;

        return (0);
}

int
control_listen(struct control_sock *cs)
{
        if (cs->cs_name == NULL)
                return (0);

        if (listen(cs->cs_fd, CONTROL_BACKLOG) == -1) {
                log_warn("control_listen: listen");
                return (-1);
        }

        event_set(&cs->cs_ev, cs->cs_fd, EV_READ,
            control_accept, cs);
        event_add(&cs->cs_ev, NULL);
        evtimer_set(&cs->cs_evt, control_accept, cs);

        return (0);
}

void
control_cleanup(struct control_sock *cs)
{
        struct ctl_conn *c, *nc;

        if (cs->cs_name == NULL)
                return;

        TAILQ_FOREACH_SAFE(c, &ctl_conns, entry, nc)
                control_close(c->iev.ibuf.fd, cs);

        event_del(&cs->cs_ev);
        event_del(&cs->cs_evt);
        (void)unlink(cs->cs_name);
}

#include <stdio.h>
void
control_accept(int listenfd, short event, void *arg)
{
        struct control_sock     *cs = (struct control_sock *)arg;
        int                      connfd;
        socklen_t                len;
        struct sockaddr_un       sun;
        struct ctl_conn         *c;

        event_add(&cs->cs_ev, NULL);
        if ((event & EV_TIMEOUT))
                return;

        len = sizeof(sun);
        if ((connfd = accept4(listenfd,
            (struct sockaddr *)&sun, &len, 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(&cs->cs_ev);
                        evtimer_add(&cs->cs_evt, &evtpause);
                } else if (errno != EWOULDBLOCK && errno != EINTR)
                        log_warn("control_accept: accept");
                return;
        }

        if ((c = calloc(1, sizeof(struct ctl_conn))) == NULL) {
                log_warn("control_accept");
                close(connfd);
                return;
        }
        if ((c->ctx = npppd_ctl_create(cs->cs_ctx)) == NULL) {
                log_warn("control_accept");
                close(connfd);
                free(c);
                return;
        }

        if (imsgbuf_init(&c->iev.ibuf, connfd) == -1) {
                log_warn("control_accept");
                close(connfd);
                free(c->ctx);
                free(c);
                return;
        }

        c->iev.handler = control_dispatch_imsg;
        c->iev.events = EV_READ;
        c->iev.data = cs;
        event_set(&c->iev.ev, c->iev.ibuf.fd, c->iev.events,
            c->iev.handler, cs);
        event_add(&c->iev.ev, NULL);

        TAILQ_INSERT_TAIL(&ctl_conns, c, entry);
}

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);
}

void
control_close(int fd, struct control_sock *cs)
{
        struct ctl_conn *c;

        if ((c = control_connbyfd(fd)) == NULL) {
                log_warn("control_close: fd %d: not found", 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(&cs->cs_evt, NULL)) {
                evtimer_del(&cs->cs_evt);
                event_add(&cs->cs_ev, NULL);
        }
        npppd_ctl_destroy(c->ctx);

        free(c);
}

void
control_dispatch_imsg(int fd, short event, void *arg)
{
        struct control_sock     *cs = (struct control_sock *)arg;
        struct ctl_conn         *c;
        struct imsg              imsg;
        int                      n, retval;

        if ((c = control_connbyfd(fd)) == NULL) {
                log_warn("control_dispatch_imsg: fd %d: not found", fd);
                return;
        }


        if (event & EV_WRITE) {
                if (imsgbuf_write(&c->iev.ibuf) == -1) {
                        control_close(fd, cs);
                        return;
                }
                if (imsgbuf_queuelen(&c->iev.ibuf) == 0)
                        npppd_ctl_imsg_compose(c->ctx, &c->iev.ibuf);
                imsg_event_add(&c->iev);
                if (!(event & EV_READ))
                        return;
        }
        if (event & EV_READ) {
                if (imsgbuf_read(&c->iev.ibuf) != 1) {
                        control_close(fd, cs);
                        return;
                }
        }

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

                if (n == 0)
                        break;

                if (cs->cs_restricted || (c->flags & CTL_CONN_LOCKED)) {
                        switch (imsg.hdr.type) {
                        default:
                                log_debug("control_dispatch_imsg: "
                                    "client requested restricted command");
                                imsg_free(&imsg);
                                control_close(fd, cs);
                                return;
                        }
                }

                switch (imsg.hdr.type) {
                case IMSG_CTL_NOP:
                        imsg_compose(&c->iev.ibuf, IMSG_CTL_OK, 0, 0, -1,
                            NULL, 0);
                        break;

                case IMSG_CTL_WHO:
                case IMSG_CTL_MONITOR:
                case IMSG_CTL_WHO_AND_MONITOR:
                        if (imsg.hdr.type == IMSG_CTL_WHO)
                                retval = npppd_ctl_who(c->ctx);
                        else if (imsg.hdr.type == IMSG_CTL_MONITOR)
                                retval = npppd_ctl_monitor(c->ctx);
                        else
                                retval = npppd_ctl_who_and_monitor(c->ctx);
                        imsg_compose(&c->iev.ibuf,
                            (retval == 0)? IMSG_CTL_OK : IMSG_CTL_FAIL, 0, 0,
                            -1, NULL, 0);
                        break;

                case IMSG_CTL_DISCONNECT:
                    {
                        struct npppd_disconnect_request  *req;
                        struct npppd_disconnect_response  res;

                        req = (struct npppd_disconnect_request *)imsg.data;
                        retval = npppd_ctl_disconnect(c->ctx,
                            req->ppp_id, req->count);
                        res.count = retval;
                        imsg_compose(&c->iev.ibuf, IMSG_CTL_OK, 0, 0,
                            -1, &res, sizeof(res));
                        break;
                    }
                default:
                        imsg_compose(&c->iev.ibuf, IMSG_CTL_FAIL, 0, 0, -1,
                            NULL, 0);
                        break;
                }
                imsg_free(&imsg);
        }
        if (imsgbuf_queuelen(&c->iev.ibuf) == 0)
                npppd_ctl_imsg_compose(c->ctx, &c->iev.ibuf);
        imsg_event_add(&c->iev);
}

void
control_imsg_forward(struct imsg *imsg)
{
        struct ctl_conn *c;

        TAILQ_FOREACH(c, &ctl_conns, entry)
                if (c->flags & CTL_CONN_NOTIFY)
                        imsg_compose(&c->iev.ibuf, imsg->hdr.type, 0,
                            imsg->hdr.pid, -1, imsg->data,
                            imsg->hdr.len - IMSG_HEADER_SIZE);
}