nts: use shorter NTS-KE retry interval when network is down

When chronyd configured with an NTS source not specified as offline and
resolvable without network was started before the network was up, it was
using an unnecessarily long NTS-KE retry interval, same as if the server
was refusing the connections.

When the network is down, the connect() call made from NKC_Start() on
the non-blocking TCP socket should fail with a different error than
EINPROGRESS and cause NKC_Start() to return with failure. Add a constant
2-second retry interval (matching default iburst) for this case.

diff --git a/nts_ntp_client.c b/nts_ntp_client.c
index 5b9c687b3f1f81d8c7ff6cf1d7d2798324104238..10cf0712205d2a3a0a8e536c9ca063a5d3ff7801 100644 (file)
--- a/nts_ntp_client.c
+++ b/nts_ntp_client.c
@@ -46,6 +46,9 @@
 /* Maximum length of all cookies to avoid IP fragmentation */
 #define MAX_TOTAL_COOKIE_LENGTH (8 * 108)
 
+/* Retry interval for NTS-KE start (which doesn't generate network traffic) */
+#define RETRY_INTERVAL_KE_START 2.0
+
 /* Magic string of files containing keys and cookies */
 #define DUMP_IDENTIFIER "NNC0\n"
 
@@ -203,10 +206,15 @@ set_ntp_address(NNC_Instance inst, NTP_Remote_Address *negotiated_address)
 /* ================================================== */
 
 static void
-update_next_nke_attempt(NNC_Instance inst, double now)
+update_next_nke_attempt(NNC_Instance inst, int failed_start, double now)
 {
   int factor, interval;
 
+  if (failed_start) {
+    inst->next_nke_attempt = now + RETRY_INTERVAL_KE_START;
+    return;
+  }
+
   if (!inst->nke)
     return;
 
@@ -221,8 +229,8 @@ static int
 get_cookies(NNC_Instance inst)
 {
   NTP_Remote_Address ntp_address;
+  int got_data, failed_start = 0;
   double now;
-  int got_data;
 
   assert(inst->num_cookies == 0);
 
@@ -241,10 +249,10 @@ get_cookies(NNC_Instance inst)
     inst->nke_attempts++;
 
     if (!NKC_Start(inst->nke))
-      ;
+      failed_start = 1;
   }
 
-  update_next_nke_attempt(inst, now);
+  update_next_nke_attempt(inst, failed_start, now);
 
   /* Wait until the session stops */
   if (NKC_IsActive(inst->nke))