pinger.c

/*
 * pinger.c: centralised module that deals with sending TS_PING
 * keepalives, to avoid replicating this code in multiple backends.
 */

#include "putty.h"

struct pinger_tag {
  int interval;
  int pending;
  unsigned long when_set, next;
  Backend *back;
  void *backhandle;
};

static void pinger_schedule(Pinger pinger);

static void pinger_timer(void *ctx, unsigned long now)
{
  Pinger pinger = (Pinger)ctx;

  if (pinger->pending && now == pinger->next) {
    pinger->back->special(pinger->backhandle, TS_PING);
    pinger->pending = FALSE;
    pinger_schedule(pinger);
  }
}

static void pinger_schedule(Pinger pinger)
{
  unsigned long next;

  if (!pinger->interval) {
    pinger->pending = FALSE; /* cancel any pending ping */
    return;
  }

  next = schedule_timer(pinger->interval * TICKSPERSEC, pinger_timer, pinger);
  if (!pinger->pending ||
      (next - pinger->when_set) < (pinger->next - pinger->when_set)) {
    pinger->next = next;
    pinger->when_set = timing_last_clock();
    pinger->pending = TRUE;
  }
}

Pinger pinger_new(Conf *conf, Backend *back, void *backhandle)
{
  Pinger pinger = snew(struct pinger_tag);

  pinger->interval = conf_get_int(conf, CONF_ping_interval);
  pinger->pending = FALSE;
  pinger->back = back;
  pinger->backhandle = backhandle;
  pinger_schedule(pinger);

  return pinger;
}

void pinger_reconfig(Pinger pinger, Conf *oldconf, Conf *newconf)
{
  int newinterval = conf_get_int(newconf, CONF_ping_interval);
  if (conf_get_int(oldconf, CONF_ping_interval) != newinterval) {
    pinger->interval = newinterval;
    pinger_schedule(pinger);
  }
}

void pinger_free(Pinger pinger)
{
  expire_timer_context(pinger);
  sfree(pinger);
}