pinger.c

   1 /*
   2  * pinger.c: centralised module that deals with sending TS_PING
   3  * keepalives, to avoid replicating this code in multiple backends.
   4  */
   5
   6 #include "putty.h"
   7
   8 struct pinger_tag {
   9     int interval;
  10     int pending;
  11     unsigned long when_set, next;
  12     Backend *back;
  13     void *backhandle;
  14 };
  15
  16 static void pinger_schedule(Pinger pinger);
  17
  18 static void pinger_timer(void *ctx, unsigned long now)
  19 {
  20     Pinger pinger = (Pinger)ctx;
  21
  22     if (pinger->pending && now == pinger->next) {
  23         pinger->back->special(pinger->backhandle, TS_PING);
  24         pinger->pending = FALSE;
  25         pinger_schedule(pinger);
  26     }
  27 }
  28
  29 static void pinger_schedule(Pinger pinger)
  30 {
  31     unsigned long next;
  32
  33     if (!pinger->interval) {
  34         pinger->pending = FALSE;       /* cancel any pending ping */
  35         return;
  36     }
  37
  38     next = schedule_timer(pinger->interval * TICKSPERSEC,
  39                           pinger_timer, pinger);
  40     if (!pinger->pending ||
  41         (next - pinger->when_set) < (pinger->next - pinger->when_set)) {
  42         pinger->next = next;
  43         pinger->when_set = timing_last_clock();
  44         pinger->pending = TRUE;
  45     }
  46 }
  47
  48 Pinger pinger_new(Conf *conf, Backend *back, void *backhandle)
  49 {
  50     Pinger pinger = snew(struct pinger_tag);
  51
  52     pinger->interval = conf_get_int(conf, CONF_ping_interval);
  53     pinger->pending = FALSE;
  54     pinger->back = back;
  55     pinger->backhandle = backhandle;
  56     pinger_schedule(pinger);
  57
  58     return pinger;
  59 }
  60
  61 void pinger_reconfig(Pinger pinger, Conf *oldconf, Conf *newconf)
  62 {
  63     int newinterval = conf_get_int(newconf, CONF_ping_interval);
  64     if (conf_get_int(oldconf, CONF_ping_interval) != newinterval) {
  65         pinger->interval = newinterval;
  66         pinger_schedule(pinger);
  67     }
  68 }
  69
  70 void pinger_free(Pinger pinger)
  71 {
  72     expire_timer_context(pinger);
  73     sfree(pinger);
  74 }