/*
 * Gophernicus
 *
 * Copyright (c) 2009-2018 Kim Holviala <kimholviala@fastmail.com>
 * Copyright (c) 2019 Gophernicus Developers <gophernicus@gophernicus.org>
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#include "gophernicus.h"


/*
 * Locate shared memory session ID
 */
#ifdef HAVE_SHMEM
int get_shm_session_id(state *st, shm_state *shm)
{
    time_t now;
    int i;

    /* Get current time */
    now = time(NULL);

    /* Locate user's old session using remote_addr */
    for (i = 0; i < SHM_SESSIONS; i++) {
        if (strcmp(st->req_remote_addr, shm->session[i].req_remote_addr) == MATCH &&
            (now - shm->session[i].req_atime) < st->session_timeout) break;
    }

    /* Return -1 on error */
    if (i == SHM_SESSIONS) return ERROR;
    else return i;
}
#endif


/*
 * Get shared memory session data
 */
#ifdef HAVE_SHMEM
void get_shm_session(state *st, shm_state *shm)
{
    int i;

    /* Get session id */
    if ((i = get_shm_session_id(st, shm)) == ERROR) return;

    /* Get session data */
    if (st->opt_vhost) {
        sstrlcpy(st->server_host, shm->session[i].server_host);
    }
}
#endif


/*
 * Update shared memory session data
 */
#ifdef HAVE_SHMEM
void update_shm_session(state *st, shm_state *shm)
{
    time_t now;
    char buf[BUFSIZE];
    int delay;
    int i;

    /* Get current time */
    now = time(NULL);

    /* No existing session found? */
    if ((i = get_shm_session_id(st, shm)) == ERROR) {

        /* Look for an empty/expired session slot */
        for (i = 0; i < SHM_SESSIONS; i++) {

            if ((now - shm->session[i].req_atime) > st->session_timeout) {

                /* Found slot -> initialize it */
                sstrlcpy(shm->session[i].req_remote_addr, st->req_remote_addr);
                shm->session[i].hits = 0;
                shm->session[i].kbytes = 0;
                shm->session[i].session_id = rand();
                break;
            }
        }
    }

    /* No available session slot found? */
    if (i == SHM_SESSIONS) return;

    /* Get referrer from old session data */
    if (*shm->session[i].server_host) {
        snprintf(buf, sizeof(buf), "gopher%s://%s:%i/%c%s",
            (shm->session[i].server_port == st->server_tls_port ? "s" : ""),
            shm->session[i].server_host,
            shm->session[i].server_port,
            shm->session[i].req_filetype,
            shm->session[i].req_selector);
        sstrlcpy(st->req_referrer, buf);
    }

    /* Get public session id */
    st->session_id = shm->session[i].session_id;

    /* Update session data */
    sstrlcpy(shm->session[i].server_host, st->server_host);
    shm->session[i].server_port = st->server_port;

    sstrlcpy(shm->session[i].req_selector, st->req_selector);
    shm->session[i].req_filetype = st->req_filetype;
    shm->session[i].req_atime = now;

    shm->session[i].hits++;
    shm->session[i].kbytes += st->req_filesize / 1024;

    /* Transfer limits exceeded? */
    if ((st->session_max_kbytes && shm->session[i].kbytes > st->session_max_kbytes) ||
        (st->session_max_hits && shm->session[i].hits > st->session_max_hits)) {

        /* Calculate throttle delay */
        delay = max(shm->session[i].kbytes / st->session_max_kbytes,
            shm->session[i].hits / st->session_max_hits);

        /* Throttle user */
#ifdef HAVE_SYSLOG
        syslog(LOG_INFO, "throttling user from %s for %i seconds",
            st->req_remote_addr, delay);
#endif
        sleep(delay);
    }
}
#endif