prop224: Make prop224 time periods smaller in testnets.

It used to be that time periods were 24 hours long even on chutney,
which made testing harder. With this commit, time periods have the same
length as a full SRV protocol run, which means that they will change
every 4 minutes in a 10-second voting interval chutney network!

src/or/hs_common.c

@@ -181,6 +181,17 @@ hs_check_service_private_dir(const char *username, const char *path,
 STATIC uint64_t
 get_time_period_length(void)
 {
+  /* If we are on a test network, make the time period smaller than normal so
+     that we actually see it rotate. Specifically, make it the same length as
+     an SRV protocol run. */
+  if (get_options()->TestingTorNetwork) {
+    unsigned run_duration = sr_state_get_protocol_run_duration();
+    /* An SRV run should take more than a minute (it's 24 rounds) */
+    tor_assert_nonfatal(run_duration > 60);
+    /* Turn it from seconds to minutes before returning: */
+    return sr_state_get_protocol_run_duration() / 60;
+  }
+
   int32_t time_period_length = networkstatus_get_param(NULL, "hsdir-interval",
                                              HS_TIME_PERIOD_LENGTH_DEFAULT,
                                              HS_TIME_PERIOD_LENGTH_MIN,