timesyncd: wait before reconnecting to first server

When all servers are exhausted, wait for one poll interval before trying
to connect again to the first server in the list. Also, keep increasing
the polling interval to make sure a client not getting any valid replies
will not send requests to any server more frequently than is allowed by
the maximum polling interval.

diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index 696dd10e69fd0cb0cccae7f8f4213e96bf7f7784..b7b39ef8222d2a777393cea54c44e3ccef56ff85 100644 (file)
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -875,6 +875,7 @@ int manager_connect(Manager *m) {
                         manager_set_server_name(m, m->current_server_name->names_next);
                 else {
                         ServerName *f;
+                        bool restart = true;
 
                         /* Our current server name list is exhausted,
                          * let's find the next one to iterate. First
@@ -891,6 +892,8 @@ int manager_connect(Manager *m) {
                                 f = m->link_servers;
                                 if (!f)
                                         f = m->system_servers;
+                                else
+                                        restart = false;
                         }
 
                         if (!f)
@@ -902,6 +905,25 @@ int manager_connect(Manager *m) {
                                 return 0;
                         }
 
+                        if (restart && !m->exhausted_servers && m->poll_interval_usec) {
+                                log_debug("Waiting after exhausting servers.");
+                                r = sd_event_add_time(m->event, &m->event_retry, clock_boottime_or_monotonic(), now(clock_boottime_or_monotonic()) + m->poll_interval_usec, 0, manager_retry_connect, m);
+                                if (r < 0) {
+                                        log_error("Failed to create retry timer: %s", strerror(-r));
+                                        return r;
+                                }
+
+                                m->exhausted_servers = true;
+
+                                /* Increase the polling interval */
+                                if (m->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+                                        m->poll_interval_usec *= 2;
+
+                                return 0;
+                        }
+
+                        m->exhausted_servers = false;
+
                         manager_set_server_name(m, f);
                 }
 
@@ -1042,7 +1064,7 @@ static int manager_network_event_handler(sd_event_source *s, int fd, uint32_t re
         online = network_is_online();
 
         /* check if the client is currently connected */
-        connected = m->server_socket >= 0 || m->resolve_query;
+        connected = m->server_socket >= 0 || m->resolve_query || m->exhausted_servers;
 
         if (connected && !online) {
                 log_info("No network connectivity, watching for changes.");

diff --git a/src/timesync/timesyncd-manager.h b/src/timesync/timesyncd-manager.h
index 2345bf8f3684ebc2a66ddf4cf1be36a567279450..bb3e50915e1aa7487a6748a0f6986039fdc03253 100644 (file)
--- a/src/timesync/timesyncd-manager.h
+++ b/src/timesync/timesyncd-manager.h
@@ -41,6 +41,7 @@ struct Manager {
         LIST_HEAD(ServerName, fallback_servers);
 
         RateLimit ratelimit;
+        bool exhausted_servers;
 
         /* network */
         sd_event_source *network_event_source;