/*      $OpenBSD: frontend.c,v 1.4 2024/11/21 13:34:51 claudio Exp $    */

/*
 * Copyright (c) 2017 Eric Faurot <eric@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/tree.h>

#include <errno.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdlib.h>
#include <syslog.h>
#include <unistd.h>

#include "lpd.h"

#include "log.h"
#include "proc.h"

static void frontend_shutdown(void);
static void frontend_listen(struct listener *);
static void frontend_pause(struct listener *);
static void frontend_resume(struct listener *);
static void frontend_accept(int, short, void *);
static void frontend_dispatch_priv(struct imsgproc *, struct imsg *, void *);
static void frontend_dispatch_engine(struct imsgproc *, struct imsg *, void *);

struct conn {
        SPLAY_ENTRY(conn)        entry;
        struct listener         *listener;
        uint32_t                 id;
};

static int conn_cmp(struct conn *, struct conn *);

SPLAY_HEAD(conntree, conn);
SPLAY_PROTOTYPE(conntree, conn, entry, conn_cmp);

static struct conntree conns;
static struct lpd_conf *tmpconf;

static int
conn_cmp(struct conn *a, struct conn *b)
{
        if (a->id < b->id)
                return (-1);
        if (a->id > b->id)
                return (1);
        return (0);
}

SPLAY_GENERATE(conntree, conn, entry, conn_cmp);

void
frontend(int debug, int verbose)
{
        struct passwd *pw;

        /* Early initialisation. */
        log_init(debug, LOG_LPR);
        log_setverbose(verbose);
        log_procinit("frontend");
        setproctitle("frontend");

        SPLAY_INIT(&conns);
        lpr_init();

        /* Drop privileges. */
        if ((pw = getpwnam(LPD_USER)) == NULL)
                fatal("%s: getpwnam: %s", __func__, LPD_USER);

        if (chroot(_PATH_VAREMPTY) == -1)
                fatal("%s: chroot", __func__);
        if (chdir("/") == -1)
                fatal("%s: chdir", __func__);

        if (setgroups(1, &pw->pw_gid) ||
            setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
            setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
                fatal("%s: cannot drop privileges", __func__);

        if (pledge("stdio unix inet recvfd sendfd", NULL) == -1)
                fatal("%s: pledge", __func__);

        event_init();

        signal(SIGPIPE, SIG_IGN);

        /* Setup parent imsg socket. */
        p_priv = proc_attach(PROC_PRIV, 3);
        if (p_priv == NULL)
                fatal("%s: proc_attach", __func__);
        proc_setcallback(p_priv, frontend_dispatch_priv, NULL);
        proc_enable(p_priv);

        event_dispatch();

        frontend_shutdown();
}

void
frontend_conn_closed(uint32_t connid)
{
        struct listener *l;
        struct conn key, *conn;

        key.id = connid;
        conn = SPLAY_FIND(conntree, &conns, &key);
        if (conn == NULL)
                fatalx("%s: %08x unknown connid", __func__, connid);

        l = conn->listener;

        if (log_getverbose() > LOGLEVEL_CONN)
                log_debug("%08x close %s", conn->id,
                    log_fmt_proto(l->proto));

        SPLAY_REMOVE(conntree, &conns, conn);
        free(conn);

        if (l->pause)
                frontend_resume(l);
}

static void
frontend_shutdown()
{
        struct listener *l;

        TAILQ_FOREACH(l, &env->listeners, entry)
                close(l->sock);

        log_debug("exiting");

        exit(0);
}

static void
frontend_listen(struct listener *l)
{
        if (log_getverbose() > LOGLEVEL_CONN)
                log_debug("listen %s %s", log_fmt_proto(l->proto),
                    log_fmt_sockaddr((struct sockaddr*)&l->ss));

        if (listen(l->sock, 5) == -1)
                fatal("%s: listen", __func__);

        frontend_resume(l);
}

static void
frontend_pause(struct listener *l)
{
        struct timeval tv;

        event_del(&l->ev);

        tv.tv_sec = 2;
        tv.tv_usec = 0;

        evtimer_set(&l->ev, frontend_accept, l);
        evtimer_add(&l->ev, &tv);
        l->pause = 1;
}

static void
frontend_resume(struct listener *l)
{
        if (l->pause) {
                evtimer_del(&l->ev);
                l->pause = 0;
        }
        event_set(&l->ev, l->sock, EV_READ | EV_PERSIST, frontend_accept, l);
        event_add(&l->ev, NULL);
}

static void
frontend_accept(int sock, short ev, void *arg)
{
        struct listener *l = arg;
        struct sockaddr_storage ss;
        struct sockaddr *sa;
        struct conn *conn;
        socklen_t len;

        if (l->pause) {
                l->pause = 0;
                frontend_resume(l);
                return;
        }

        conn = calloc(1, sizeof(*conn));
        if (conn == NULL)
                log_warn("%s: calloc", __func__);

        sa = (struct sockaddr *)&ss;
        len = sizeof(ss);
        sock = accept4(sock, sa, &len, SOCK_NONBLOCK);
        if (sock == -1) {
                if (errno == ENFILE || errno == EMFILE)
                        frontend_pause(l);
                else if (errno != EWOULDBLOCK && errno != EINTR &&
                    errno != ECONNABORTED)
                        log_warn("%s: accept4", __func__);
                free(conn);
                return;
        }

        if (conn == NULL) {
                close(sock);
                return;
        }

        while (conn->id == 0 || SPLAY_FIND(conntree, &conns, conn))
                conn->id = arc4random();
        SPLAY_INSERT(conntree, &conns, conn);
        conn->listener = l;

        if (log_getverbose() > LOGLEVEL_CONN)
                log_debug("%08x accept %s %s", conn->id,
                    log_fmt_proto(conn->listener->proto),
                    log_fmt_sockaddr((struct sockaddr*)&ss));

        switch (l->proto) {
        case PROTO_LPR:
                lpr_conn(conn->id, l, sock, sa);
                break;
        default:
                fatalx("%s: unexpected protocol %d", __func__, l->proto);
        }
}

static void
frontend_dispatch_priv(struct imsgproc *proc, struct imsg *imsg, void *arg)
{
        struct listener *l;
        int fd;

        if (imsg == NULL) {
                log_debug("%s: imsg connection lost", __func__);
                event_loopexit(NULL);
                return;
        }

        if (log_getverbose() > LOGLEVEL_IMSG)
                log_imsg(proc, imsg);

        switch (imsg->hdr.type) {
        case IMSG_SOCK_ENGINE:
                if ((fd = imsg_get_fd(imsg)) == -1)
                        fatalx("%s: engine socket not received", __func__);
                m_end(proc);
                p_engine = proc_attach(PROC_ENGINE, fd);
                proc_setcallback(p_engine, frontend_dispatch_engine, NULL);
                proc_enable(p_engine);
                break;

        case IMSG_CONF_START:
                m_end(proc);
                if ((tmpconf = calloc(1, sizeof(*tmpconf))) == NULL)
                        fatal("%s: calloc", __func__);
                TAILQ_INIT(&tmpconf->listeners);
                break;

        case IMSG_CONF_LISTENER:
                if ((fd = imsg_get_fd(imsg)) == -1)
                        fatalx("%s: listener socket not received", __func__);
                if ((l = calloc(1, sizeof(*l))) == NULL)
                        fatal("%s: calloc", __func__);
                m_get_int(proc, &l->proto);
                m_get_sockaddr(proc, (struct sockaddr *)&l->ss);
                m_end(proc);
                l->sock = fd;
                TAILQ_INSERT_TAIL(&tmpconf->listeners, l, entry);
                break;

        case IMSG_CONF_END:
                m_end(proc);
                TAILQ_FOREACH(l, &tmpconf->listeners, entry)
                        frontend_listen(l);
                env = tmpconf;
                break;

        default:
                fatalx("%s: unexpected imsg %s", __func__,
                    log_fmt_imsgtype(imsg->hdr.type));
        }
}

static void
frontend_dispatch_engine(struct imsgproc *proc, struct imsg *imsg, void *arg)
{
        if (imsg == NULL) {
                log_debug("%s: imsg connection lost", __func__);
                event_loopexit(NULL);
                return;
        }

        if (log_getverbose() > LOGLEVEL_IMSG)
                log_imsg(proc, imsg);

        switch (imsg->hdr.type) {
        case IMSG_GETADDRINFO:
        case IMSG_GETADDRINFO_END:
        case IMSG_GETNAMEINFO:
                resolver_dispatch_result(proc, imsg);
                break;

        case IMSG_LPR_ALLOWEDHOST:
        case IMSG_LPR_DISPLAYQ:
        case IMSG_LPR_RECVJOB:
        case IMSG_LPR_RECVJOB_CF:
        case IMSG_LPR_RECVJOB_DF:
        case IMSG_LPR_RMJOB:
                lpr_dispatch_engine(proc, imsg);
                break;

        default:
                fatalx("%s: unexpected imsg %s", __func__,
                    log_fmt_imsgtype(imsg->hdr.type));
        }
}