/* -*- mode: c; c-file-style: "openbsd" -*- */

/*

 * Copyright (c) 2012 Vincent Bernat <bernat@luffy.cx>

 *

 * Permission to use, copy, modify, and/or 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 "lldpd.h"

#include "trace.h"

#include <unistd.h>

#include <signal.h>

#include <errno.h>

#include <time.h>

#include <fcntl.h>

#if defined(__clang__)

#  pragma clang diagnostic push

#  pragma clang diagnostic ignored "-Wdocumentation"

#endif

#include <event2/event.h>

#include <event2/bufferevent.h>

#include <event2/buffer.h>

#if defined(__clang__)

#  pragma clang diagnostic pop

#endif

#define EVENT_BUFFER 1024

static void

levent_log_cb(int severity, const char *msg)

{

  switch (severity) {

  case _EVENT_LOG_DEBUG:

    log_debug("libevent", "%s", msg);

    break;

  case _EVENT_LOG_MSG:

    log_info("libevent", "%s", msg);

    break;

  case _EVENT_LOG_WARN:

    log_warnx("libevent", "%s", msg);

    break;

  case _EVENT_LOG_ERR:

    log_warnx("libevent", "%s", msg);

    break;

  }

}

struct lldpd_events {

  TAILQ_ENTRY(lldpd_events) next;

  struct event *ev;

};

TAILQ_HEAD(ev_l, lldpd_events);

#define levent_snmp_fds(cfg) ((struct ev_l *)(cfg)->g_snmp_fds)

#define levent_hardware_fds(hardware) ((struct ev_l *)(hardware)->h_recv)

#ifdef USE_SNMP

#  include <net-snmp/net-snmp-config.h>

#  include <net-snmp/net-snmp-includes.h>

#  include <net-snmp/agent/net-snmp-agent-includes.h>

#  include <net-snmp/agent/snmp_vars.h>

/* Compatibility with older versions of NetSNMP */

#  ifndef HAVE_SNMP_SELECT_INFO2

#    define netsnmp_large_fd_set fd_set

#    define snmp_read2 snmp_read

#    define snmp_select_info2 snmp_select_info

#    define netsnmp_large_fd_set_init(...)

#    define netsnmp_large_fd_set_cleanup(...)

#    define NETSNMP_LARGE_FD_SET FD_SET

#    define NETSNMP_LARGE_FD_CLR FD_CLR

#    define NETSNMP_LARGE_FD_ZERO FD_ZERO

#    define NETSNMP_LARGE_FD_ISSET FD_ISSET

#  else

#    include <net-snmp/library/large_fd_set.h>

#  endif

static void levent_snmp_update(struct lldpd *);

/*

 * Callback function when we have something to read from SNMP.

 *

 * This function is called because we have a read event on one SNMP

 * file descriptor. When need to call snmp_read() on it.

 */

static void

levent_snmp_read(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd *cfg = arg;

  netsnmp_large_fd_set fdset;

  (void)what;

  netsnmp_large_fd_set_init(&fdset, FD_SETSIZE);

  NETSNMP_LARGE_FD_ZERO(&fdset);

  NETSNMP_LARGE_FD_SET(fd, &fdset);

  snmp_read2(&fdset);

  netsnmp_large_fd_set_cleanup(&fdset);

  levent_snmp_update(cfg);

}

/*

 * Callback function for a SNMP timeout.

 *

 * A SNMP timeout has occurred. Call `snmp_timeout()` to handle it.

 */

static void

levent_snmp_timeout(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd *cfg = arg;

  (void)what;

  (void)fd;

  snmp_timeout();

  run_alarms();

  levent_snmp_update(cfg);

}

/*

 * Watch a new SNMP FD.

 *

 * @param base The libevent base we are working on.

 * @param fd The file descriptor we want to watch.

 *

 * The file descriptor is appended to the list of file descriptors we

 * want to watch.

 */

static void

levent_snmp_add_fd(struct lldpd *cfg, int fd)

{

  struct event_base *base = cfg->g_base;

  struct lldpd_events *snmpfd = calloc(1, sizeof(struct lldpd_events));

  if (!snmpfd) {

    log_warn("event", "unable to allocate memory for new SNMP event");

    return;

  }

  levent_make_socket_nonblocking(fd);

  if ((snmpfd->ev = event_new(base, fd, EV_READ | EV_PERSIST, levent_snmp_read,

     cfg)) == NULL) {

    log_warnx("event", "unable to allocate a new SNMP event for FD %d", fd);

    free(snmpfd);

    return;

  }

  if (event_add(snmpfd->ev, NULL) == -1) {

    log_warnx("event", "unable to schedule new SNMP event for FD %d", fd);

    event_free(snmpfd->ev);

    free(snmpfd);

    return;

  }

  TAILQ_INSERT_TAIL(levent_snmp_fds(cfg), snmpfd, next);

}

/*

 * Update SNMP event loop.

 *

 * New events are added and some other are removed. This function

 * should be called every time a SNMP event happens: either when

 * handling a SNMP packet, a SNMP timeout or when sending a SNMP

 * packet. This function will keep libevent in sync with NetSNMP.

 *

 * @param base The libevent base we are working on.

 */

static void

levent_snmp_update(struct lldpd *cfg)

{

  int maxfd = 0;

  int block = 1;

  struct timeval timeout;

  static int howmany = 0;

  int added = 0, removed = 0, current = 0;

  struct lldpd_events *snmpfd, *snmpfd_next;

  /* snmp_select_info() can be tricky to understand. We set `block` to

     1 to means that we don't request a timeout. snmp_select_info()

     will reset `block` to 0 if it wants us to set up a timeout. In

     this timeout, `snmp_timeout()` should be invoked.

     Each FD in `fdset` will need to be watched for reading. If one of

     them become active, `snmp_read()` should be called on it.

  */

  netsnmp_large_fd_set fdset;

  netsnmp_large_fd_set_init(&fdset, FD_SETSIZE);

  NETSNMP_LARGE_FD_ZERO(&fdset);

  snmp_select_info2(&maxfd, &fdset, &timeout, &block);

  /* We need to untrack any event whose FD is not in `fdset`

     anymore */

  for (snmpfd = TAILQ_FIRST(levent_snmp_fds(cfg)); snmpfd; snmpfd = snmpfd_next) {

    snmpfd_next = TAILQ_NEXT(snmpfd, next);

    if (event_get_fd(snmpfd->ev) >= maxfd ||

        (!NETSNMP_LARGE_FD_ISSET(event_get_fd(snmpfd->ev), &fdset))) {

      event_free(snmpfd->ev);

      TAILQ_REMOVE(levent_snmp_fds(cfg), snmpfd, next);

      free(snmpfd);

      removed++;

    } else {

      NETSNMP_LARGE_FD_CLR(event_get_fd(snmpfd->ev), &fdset);

      current++;

    }

  }

  /* Invariant: FD in `fdset` are not in list of FD */

  for (int fd = 0; fd < maxfd; fd++) {

    if (NETSNMP_LARGE_FD_ISSET(fd, &fdset)) {

      levent_snmp_add_fd(cfg, fd);

      added++;

    }

  }

  current += added;

  if (howmany != current) {

    log_debug("event",

        "added %d events, removed %d events, total of %d events", added,

        removed, current);

    howmany = current;

  }

  /* If needed, handle timeout */

  if (evtimer_add(cfg->g_snmp_timeout, block ? NULL : &timeout) == -1)

    log_warnx("event", "unable to schedule timeout function for SNMP");

  netsnmp_large_fd_set_cleanup(&fdset);

}

#endif /* USE_SNMP */

struct lldpd_one_client {

  TAILQ_ENTRY(lldpd_one_client) next;

  struct lldpd *cfg;

  struct bufferevent *bev;

  int subscribed; /* Is this client subscribed to changes? */

};

TAILQ_HEAD(, lldpd_one_client) lldpd_clients;

static void

levent_ctl_free_client(struct lldpd_one_client *client)

{

  if (client && client->bev) bufferevent_free(client->bev);

  if (client) {

    TAILQ_REMOVE(&lldpd_clients, client, next);

    free(client);

  }

}

static void

levent_ctl_close_clients()

{

  struct lldpd_one_client *client, *client_next;

  for (client = TAILQ_FIRST(&lldpd_clients); client; client = client_next) {

    client_next = TAILQ_NEXT(client, next);

    levent_ctl_free_client(client);

  }

}

static ssize_t

levent_ctl_send(struct lldpd_one_client *client, int type, void *data, size_t len)

{

  struct bufferevent *bev = client->bev;

  struct hmsg_header hdr = { .len = len, .type = type };

  bufferevent_disable(bev, EV_WRITE);

  if (bufferevent_write(bev, &hdr, sizeof(struct hmsg_header)) == -1 ||

      (len > 0 && bufferevent_write(bev, data, len) == -1)) {

    log_warnx("event", "unable to create answer to client");

    levent_ctl_free_client(client);

    return -1;

  }

  bufferevent_enable(bev, EV_WRITE);

  return len;

}

void

levent_ctl_notify(char *ifname, int state, struct lldpd_port *neighbor)

{

  struct lldpd_one_client *client, *client_next;

  struct lldpd_neighbor_change neigh = { .ifname = ifname,

    .state = state,

    .neighbor = neighbor };

  void *output = NULL;

  ssize_t output_len = 0;

  /* Don't use TAILQ_FOREACH, the client may be deleted in case of errors. */

  log_debug("control", "notify clients of neighbor changes");

  for (client = TAILQ_FIRST(&lldpd_clients); client; client = client_next) {

    client_next = TAILQ_NEXT(client, next);

    if (!client->subscribed) continue;

    if (output == NULL) {

      /* Ugly hack: we don't want to transmit a list of

       * ports. We patch the port to avoid this. */

      TAILQ_ENTRY(lldpd_port) backup_p_entries;

      memcpy(&backup_p_entries, &neighbor->p_entries,

          sizeof(backup_p_entries));

      memset(&neighbor->p_entries, 0, sizeof(backup_p_entries));

      output_len = lldpd_neighbor_change_serialize(&neigh, &output);

      memcpy(&neighbor->p_entries, &backup_p_entries,

          sizeof(backup_p_entries));

      if (output_len <= 0) {

        log_warnx("event",

            "unable to serialize changed neighbor");

        return;

      }

    }

    levent_ctl_send(client, NOTIFICATION, output, output_len);

  }

  free(output);

}

static ssize_t

levent_ctl_send_cb(void *out, int type, void *data, size_t len)

{

  struct lldpd_one_client *client = out;

  return levent_ctl_send(client, type, data, len);

}

static void

levent_ctl_recv(struct bufferevent *bev, void *ptr)

{

  struct lldpd_one_client *client = ptr;

  struct evbuffer *buffer = bufferevent_get_input(bev);

  size_t buffer_len = evbuffer_get_length(buffer);

  struct hmsg_header hdr;

  void *data = NULL;

  log_debug("control", "receive data on Unix socket");

  if (buffer_len < sizeof(struct hmsg_header)) return; /* Not enough data yet */

  if (evbuffer_copyout(buffer, &hdr, sizeof(struct hmsg_header)) !=

      sizeof(struct hmsg_header)) {

    log_warnx("event", "not able to read header");

    return;

  }

  if (hdr.len > HMSG_MAX_SIZE) {

    log_warnx("event", "message received is too large");

    goto recv_error;

  }

  if (buffer_len < hdr.len + sizeof(struct hmsg_header))

    return; /* Not enough data yet */

  if (hdr.len > 0 && (data = malloc(hdr.len)) == NULL) {

    log_warnx("event", "not enough memory");

    goto recv_error;

  }

  evbuffer_drain(buffer, sizeof(struct hmsg_header));

  if (hdr.len > 0) evbuffer_remove(buffer, data, hdr.len);

  /* Currently, we should not receive notification acknowledgment. But if

   * we receive one, we can discard it. */

  if (hdr.len == 0 && hdr.type == NOTIFICATION) return;

  if (client_handle_client(client->cfg, levent_ctl_send_cb, client, hdr.type,

    data, hdr.len, &client->subscribed) == -1)

    goto recv_error;

  free(data);

  return;

recv_error:

  free(data);

  levent_ctl_free_client(client);

}

static void

levent_ctl_event(struct bufferevent *bev, short events, void *ptr)

{

  struct lldpd_one_client *client = ptr;

  if (events & BEV_EVENT_ERROR) {

    log_warnx("event", "an error occurred with client: %s",

        evutil_socket_error_to_string(EVUTIL_SOCKET_ERROR()));

    levent_ctl_free_client(client);

  } else if (events & BEV_EVENT_EOF) {

    log_debug("event", "client has been disconnected");

    levent_ctl_free_client(client);

  }

}

static void

levent_ctl_accept(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd *cfg = arg;

  struct lldpd_one_client *client = NULL;

  int s;

  (void)what;

  log_debug("control", "accept a new connection");

  if ((s = accept(fd, NULL, NULL)) == -1) {

    log_warn("event", "unable to accept connection from socket");

    return;

  }

  client = calloc(1, sizeof(struct lldpd_one_client));

  if (!client) {

    log_warnx("event", "unable to allocate memory for new client");

    close(s);

    goto accept_failed;

  }

  client->cfg = cfg;

  levent_make_socket_nonblocking(s);

  TAILQ_INSERT_TAIL(&lldpd_clients, client, next);

  if ((client->bev = bufferevent_socket_new(cfg->g_base, s,

     BEV_OPT_CLOSE_ON_FREE)) == NULL) {

    log_warnx("event",

        "unable to allocate a new buffer event for new client");

    close(s);

    goto accept_failed;

  }

  bufferevent_setcb(client->bev, levent_ctl_recv, NULL, levent_ctl_event, client);

  bufferevent_enable(client->bev, EV_READ | EV_WRITE);

  log_debug("event", "new client accepted");

  /* coverity[leaked_handle]

     s has been saved by bufferevent_socket_new */

  return;

accept_failed:

  levent_ctl_free_client(client);

}

static void

levent_priv(evutil_socket_t fd, short what, void *arg)

{

  struct event_base *base = arg;

  ssize_t n;

  int err;

  char one;

  (void)what;

  /* Check if we have some data available. We need to pass the socket in

   * non-blocking mode to be able to run the check without disruption. */

  levent_make_socket_nonblocking(fd);

  n = read(fd, &one, 1);

  err = errno;

  levent_make_socket_blocking(fd);

  switch (n) {

  case -1:

    if (err == EAGAIN || err == EWOULDBLOCK) /* No data, all good */

      return;

    log_warnx("event", "unable to poll monitor process, exit");

    break;

  case 0:

    log_warnx("event", "monitor process has terminated, exit");

    break;

  default:

    /* This is a bit unsafe as we are now out-of-sync with the

     * monitor. It would be safer to request 0 byte, but some OS

     * (illumos) seem to take the shortcut that by asking 0 byte,

     * we can just return 0 byte. */

    log_warnx("event",

        "received unexpected data from monitor process, exit");

    break;

  }

  event_base_loopbreak(base);

}

static void

levent_dump(evutil_socket_t fd, short what, void *arg)

{

  struct event_base *base = arg;

  (void)fd;

  (void)what;

  log_debug("event", "dumping all events");

  event_base_dump_events(base, stderr);

}

static void

levent_stop(evutil_socket_t fd, short what, void *arg)

{

  struct event_base *base = arg;

  (void)fd;

  (void)what;

  event_base_loopbreak(base);

}

static void

levent_update_and_send(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd *cfg = arg;

  struct timeval tv;

  long interval_ms = cfg->g_config.c_tx_interval;

  (void)fd;

  (void)what;

  lldpd_loop(cfg);

  if (cfg->g_iface_event != NULL) interval_ms *= 20;

  if (interval_ms < 30000) interval_ms = 30000;

  tv.tv_sec = interval_ms / 1000;

  tv.tv_usec = (interval_ms % 1000) * 1000;

  event_add(cfg->g_main_loop, &tv);

}

void

levent_update_now(struct lldpd *cfg)

{

  if (cfg->g_main_loop) event_active(cfg->g_main_loop, EV_TIMEOUT, 1);

}

void

levent_send_now(struct lldpd *cfg)

{

  struct lldpd_hardware *hardware;

  TAILQ_FOREACH (hardware, &cfg->g_hardware, h_entries) {

    if (hardware->h_timer)

      event_active(hardware->h_timer, EV_TIMEOUT, 1);

    else

      log_warnx("event", "BUG: no timer present for interface %s",

          hardware->h_ifname);

  }

}

static void

levent_init(struct lldpd *cfg)

{

  /* Set up libevent */

  log_debug("event", "initialize libevent");

  event_set_log_callback(levent_log_cb);

  if (!(cfg->g_base = event_base_new()))

    fatalx("event", "unable to create a new libevent base");

  log_info("event", "libevent %s initialized with %s method", event_get_version(),

      event_base_get_method(cfg->g_base));

  /* Set up SNMP */

#ifdef USE_SNMP

  if (cfg->g_snmp) {

    agent_init(cfg, cfg->g_snmp_agentx);

    cfg->g_snmp_timeout =

        evtimer_new(cfg->g_base, levent_snmp_timeout, cfg);

    if (!cfg->g_snmp_timeout)

      fatalx("event", "unable to setup timeout function for SNMP");

    if ((cfg->g_snmp_fds = malloc(sizeof(struct ev_l))) == NULL)

      fatalx("event", "unable to allocate memory for SNMP events");

    TAILQ_INIT(levent_snmp_fds(cfg));

  }

#endif

  /* Setup loop that will run every X seconds. */

  log_debug("event", "register loop timer");

  if (!(cfg->g_main_loop =

        event_new(cfg->g_base, -1, 0, levent_update_and_send, cfg)))

    fatalx("event", "unable to setup main timer");

  event_active(cfg->g_main_loop, EV_TIMEOUT, 1);

  /* Set up unix socket */

  struct event *ctl_event;

  log_debug("event", "register Unix socket");

  TAILQ_INIT(&lldpd_clients);

  levent_make_socket_nonblocking(cfg->g_ctl);

  if ((ctl_event = event_new(cfg->g_base, cfg->g_ctl, EV_READ | EV_PERSIST,

     levent_ctl_accept, cfg)) == NULL)

    fatalx("event", "unable to setup control socket event");

  event_add(ctl_event, NULL);

  /* Somehow monitor the monitor process */

  struct event *monitor_event;

  log_debug("event", "monitor the monitor process");

  if ((monitor_event = event_new(cfg->g_base, priv_fd(PRIV_UNPRIVILEGED),

     EV_READ | EV_PERSIST, levent_priv, cfg->g_base)) == NULL)

    fatalx("event", "unable to monitor monitor process");

  event_add(monitor_event, NULL);

  /* Signals */

  log_debug("event", "register signals");

  evsignal_add(evsignal_new(cfg->g_base, SIGUSR1, levent_dump, cfg->g_base),

      NULL);

  evsignal_add(evsignal_new(cfg->g_base, SIGINT, levent_stop, cfg->g_base), NULL);

  evsignal_add(evsignal_new(cfg->g_base, SIGTERM, levent_stop, cfg->g_base),

      NULL);

}

/* Initialize libevent and start the event loop */

void

levent_loop(struct lldpd *cfg)

{

  levent_init(cfg);

  lldpd_loop(cfg);

#ifdef USE_SNMP

  if (cfg->g_snmp) levent_snmp_update(cfg);

#endif

  /* libevent loop */

  do {

    TRACE(LLDPD_EVENT_LOOP());

    if (event_base_got_break(cfg->g_base) ||

        event_base_got_exit(cfg->g_base))

      break;

  } while (event_base_loop(cfg->g_base, EVLOOP_ONCE) == 0);

  if (cfg->g_iface_timer_event != NULL) event_free(cfg->g_iface_timer_event);

#ifdef USE_SNMP

  if (cfg->g_snmp) agent_shutdown();

#endif /* USE_SNMP */

  levent_ctl_close_clients();

}

/* Release libevent resources */

void

levent_shutdown(struct lldpd *cfg)

{

  if (cfg->g_iface_event) event_free(cfg->g_iface_event);

  if (cfg->g_cleanup_timer) event_free(cfg->g_cleanup_timer);

  event_base_free(cfg->g_base);

}

static void

levent_hardware_recv(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd_hardware *hardware = arg;

  struct lldpd *cfg = hardware->h_cfg;

  (void)what;

  log_debug("event", "received something for %s", hardware->h_ifname);

  lldpd_recv(cfg, hardware, fd);

  levent_schedule_cleanup(cfg);

}

void

levent_hardware_init(struct lldpd_hardware *hardware)

{

  log_debug("event", "initialize events for %s", hardware->h_ifname);

  if ((hardware->h_recv = malloc(sizeof(struct ev_l))) == NULL) {

    log_warnx("event", "unable to allocate memory for %s",

        hardware->h_ifname);

    return;

  }

  TAILQ_INIT(levent_hardware_fds(hardware));

}

void

levent_hardware_add_fd(struct lldpd_hardware *hardware, int fd)

{

  struct lldpd_events *hfd = NULL;

  if (!hardware->h_recv) return;

  hfd = calloc(1, sizeof(struct lldpd_events));

  if (!hfd) {

    log_warnx("event", "unable to allocate new event for %s",

        hardware->h_ifname);

    return;

  }

  levent_make_socket_nonblocking(fd);

  if ((hfd->ev = event_new(hardware->h_cfg->g_base, fd, EV_READ | EV_PERSIST,

     levent_hardware_recv, hardware)) == NULL) {

    log_warnx("event", "unable to allocate a new event for %s",

        hardware->h_ifname);

    free(hfd);

    return;

  }

  if (event_add(hfd->ev, NULL) == -1) {

    log_warnx("event", "unable to schedule new event for %s",

        hardware->h_ifname);

    event_free(hfd->ev);

    free(hfd);

    return;

  }

  TAILQ_INSERT_TAIL(levent_hardware_fds(hardware), hfd, next);

}

void

levent_hardware_release(struct lldpd_hardware *hardware)

{

  struct lldpd_events *ev, *ev_next;

  if (hardware->h_timer) {

    event_free(hardware->h_timer);

    hardware->h_timer = NULL;

  }

  if (!hardware->h_recv) return;

  log_debug("event", "release events for %s", hardware->h_ifname);

  for (ev = TAILQ_FIRST(levent_hardware_fds(hardware)); ev; ev = ev_next) {

    ev_next = TAILQ_NEXT(ev, next);

    /* We may close several time the same FD. This is harmless. */

    close(event_get_fd(ev->ev));

    event_free(ev->ev);

    TAILQ_REMOVE(levent_hardware_fds(hardware), ev, next);

    free(ev);

  }

  free(levent_hardware_fds(hardware));

}

static void

levent_iface_trigger(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd *cfg = arg;

  log_debug("event", "triggering update of all interfaces");

  lldpd_update_localports(cfg);

}

static void

levent_iface_recv(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd *cfg = arg;

  char buffer[EVENT_BUFFER];

  int n;

  if (cfg->g_iface_cb == NULL) {

    /* Discard the message */

    while (1) {

      n = read(fd, buffer, sizeof(buffer));

      if (n == -1 && (errno == EWOULDBLOCK || errno == EAGAIN)) break;

      if (n == -1) {

        log_warn("event",

            "unable to receive interface change notification message");

        return;

      }

      if (n == 0) {

        log_warnx("event",

            "end of file reached while getting interface change notification message");

        return;

      }

    }

  } else {

    cfg->g_iface_cb(cfg);

  }

  /* Schedule local port update. We don't run it right away because we may

   * receive a batch of events like this. */

  struct timeval one_sec = { 1, 0 };

  TRACE(LLDPD_INTERFACES_NOTIFICATION());

  log_debug("event",

      "received notification change, schedule an update of all interfaces in one second");

  if (cfg->g_iface_timer_event == NULL) {

    if ((cfg->g_iface_timer_event = evtimer_new(cfg->g_base,

       levent_iface_trigger, cfg)) == NULL) {

      log_warnx("event",

          "unable to create a new event to trigger interface update");

      return;

    }

  }

  if (evtimer_add(cfg->g_iface_timer_event, &one_sec) == -1) {

    log_warnx("event", "unable to schedule interface updates");

    return;

  }

}

int

levent_iface_subscribe(struct lldpd *cfg, int socket)

{

  log_debug("event", "subscribe to interface changes from socket %d", socket);

  levent_make_socket_nonblocking(socket);

  cfg->g_iface_event = event_new(cfg->g_base, socket, EV_READ | EV_PERSIST,

      levent_iface_recv, cfg);

  if (cfg->g_iface_event == NULL) {

    log_warnx("event",

        "unable to allocate a new event for interface changes");

    return -1;

  }

  if (event_add(cfg->g_iface_event, NULL) == -1) {

    log_warnx("event", "unable to schedule new interface changes event");

    event_free(cfg->g_iface_event);

    cfg->g_iface_event = NULL;

    return -1;

  }

  return 0;

}

static void

levent_trigger_cleanup(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd *cfg = arg;

  lldpd_cleanup(cfg);

}

void

levent_schedule_cleanup(struct lldpd *cfg)

{

  log_debug("event", "schedule next cleanup");

  if (cfg->g_cleanup_timer != NULL) {

    event_free(cfg->g_cleanup_timer);

  }

  cfg->g_cleanup_timer = evtimer_new(cfg->g_base, levent_trigger_cleanup, cfg);

  if (cfg->g_cleanup_timer == NULL) {

    log_warnx("event", "unable to allocate a new event for cleanup tasks");

    return;

  }

  /* Compute the next TTL event */

  struct timeval tv = { cfg->g_config.c_ttl, 0 };

  time_t now = time(NULL);

  time_t next;

  struct lldpd_hardware *hardware;

  struct lldpd_port *port;

  TAILQ_FOREACH (hardware, &cfg->g_hardware, h_entries) {

    TAILQ_FOREACH (port, &hardware->h_rports, p_entries) {

      if (now >= port->p_lastupdate + port->p_ttl) {

        tv.tv_sec = 0;

        log_debug("event",

            "immediate cleanup on port %s (%lld, %d, %lld)",

            hardware->h_ifname, (long long)now, port->p_ttl,

            (long long)port->p_lastupdate);

        break;

      }

      next = port->p_ttl - (now - port->p_lastupdate);

      if (next < tv.tv_sec) tv.tv_sec = next;

    }

  }

  log_debug("event", "next cleanup in %ld seconds", (long)tv.tv_sec);

  if (event_add(cfg->g_cleanup_timer, &tv) == -1) {

    log_warnx("event", "unable to schedule cleanup task");

    event_free(cfg->g_cleanup_timer);

    cfg->g_cleanup_timer = NULL;

    return;

  }

}

static void

levent_send_pdu(evutil_socket_t fd, short what, void *arg)

{

  struct lldpd_hardware *hardware = arg;

  int tx_interval = hardware->h_cfg->g_config.c_tx_interval;

  log_debug("event", "trigger sending PDU for port %s", hardware->h_ifname);

  lldpd_send(hardware);

  if (hardware->h_tx_fast > 0) hardware->h_tx_fast--;

  if (hardware->h_tx_fast > 0)

    tx_interval = hardware->h_cfg->g_config.c_tx_fast_interval * 1000;

  struct timeval tv;

  tv.tv_sec = tx_interval / 1000;

  tv.tv_usec = (tx_interval % 1000) * 1000;

  if (event_add(hardware->h_timer, &tv) == -1) {

    log_warnx("event", "unable to re-register timer event for port %s",

        hardware->h_ifname);

    event_free(hardware->h_timer);

    hardware->h_timer = NULL;

    return;

  }

}

void

levent_schedule_pdu(struct lldpd_hardware *hardware)

{

  log_debug("event", "schedule sending PDU on %s", hardware->h_ifname);

  if (hardware->h_timer == NULL) {

    hardware->h_timer =

        evtimer_new(hardware->h_cfg->g_base, levent_send_pdu, hardware);

    if (hardware->h_timer == NULL) {

      log_warnx("event", "unable to schedule PDU sending for port %s",

          hardware->h_ifname);

      return;

    }

  }

  struct timeval tv = { 0, 0 };

  if (event_add(hardware->h_timer, &tv) == -1) {

    log_warnx("event", "unable to register timer event for port %s",

        hardware->h_ifname);

    event_free(hardware->h_timer);

    hardware->h_timer = NULL;

    return;

  }

}

int

levent_make_socket_nonblocking(int fd)

{

  int flags;

  if ((flags = fcntl(fd, F_GETFL, NULL)) < 0) {

    log_warn("event", "fcntl(%d, F_GETFL)", fd);

    return -1;

  }

  if (flags & O_NONBLOCK) return 0;

  if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {

    log_warn("event", "fcntl(%d, F_SETFL)", fd);

    return -1;

  }

  return 0;

}

int

levent_make_socket_blocking(int fd)

{

  int flags;

  if ((flags = fcntl(fd, F_GETFL, NULL)) < 0) {

    log_warn("event", "fcntl(%d, F_GETFL)", fd);

    return -1;

  }

  if (!(flags & O_NONBLOCK)) return 0;

  if (fcntl(fd, F_SETFL, flags & ~O_NONBLOCK) == -1) {

    log_warn("event", "fcntl(%d, F_SETFL)", fd);

    return -1;

  }

  return 0;

}

#ifdef HOST_OS_LINUX

/* Receive and log error from a socket when there is suspicion of an error. */

void

levent_recv_error(int fd, const char *source)

{

  do {

    ssize_t n;

    char buf[1024] = {};

    struct msghdr msg = { .msg_control = buf,

      .msg_controllen = sizeof(buf) };

    if ((n = recvmsg(fd, &msg, MSG_ERRQUEUE | MSG_DONTWAIT)) <= 0) {

      return;

    }

    struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);

    if (cmsg == NULL)

      log_warnx("event", "received unknown error on %s", source);

    else

      log_warnx("event", "received error (level=%d/type=%d) on %s",

          cmsg->cmsg_level, cmsg->cmsg_type, source);

  } while (1);

}

#endif