update copyright years

The commit 5dd288dc0c ("sources: reselect earlier when removing
selected source") didn't cover all paths that can lead to a missing log
message when all sources are removed.

Add a flag to track the loss of selection and postpone the log message
in transient states where no message is logged to avoid spamming in
normal operation. Call SRC_SelectSource() after removing the source
to get a log message if there are no (selectable) sources left.

Reported-by: Thomas Lange <thomas@corelatus.se>

doc/chrony.conf.adoc

@@ -339,8 +339,10 @@ Protocol (PTP) correction field in NTP-over-PTP messages updated by one-step
 end-to-end transparent clocks in network switches and routers to significantly
 improve accuracy and stability of the synchronisation. NTP-over-PTP can be
 enabled by the <<ptpport,*ptpport*>> directive and setting the *port* option to
-the PTP port. This field should be enabled only for servers known to be running
+the PTP port. The corrections are applied only to NTP measurements with HW
-*chronyd* version 4.5 or later.
+timestamps (enabled by the <<hwtimestamp,*hwtimestamp*>> directive). This
+field should be enabled only for servers known to be running *chronyd* version
+4.5 or later.
 {blank}:::
 
 [[pool]]*pool* _name_ [_option_]...::

doc/chronyc.adoc

@@ -986,6 +986,10 @@ command might replace the addresses even if they are still in the pool.
 The *reload sources* command causes *chronyd* to re-read all _*.sources_ files
 from the directories specified by the
 <<chrony.conf.adoc#sourcedir,*sourcedir*>> directive.
++
+Note that modified sources (e.g. specified with a new option) are not modified
+in memory. They are removed and added again, which causes them to lose old
+measurements and reset the selection state.
 
 [[sourcename]]*sourcename* _address_::
 The *sourcename* command prints the original hostname or address that was

doc/faq.adoc

@@ -1,6 +1,7 @@
 // This file is part of chrony
 //
 // Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Luke Valenta  2023
 // Copyright (C) Miroslav Lichvar  2014-2016, 2020-2023
 //
 // This program is free software; you can redistribute it and/or modify
@@ -381,7 +382,7 @@ outliers corrupting the minimum delay. For example:
 server ntp.local minpoll -7 maxpoll -7 filter 31 maxdelayquant 0.3 xleave
 ----
 
-As an experimental feature added in version 4.2, `chronyd` supports an NTPv4
+Since version 4.2, `chronyd` supports an NTPv4
 extension field containing an additional timestamp to enable frequency transfer
 and significantly improve stability of synchronisation. It can be enabled by
 the `extfield F323` option. For example:
@@ -390,6 +391,18 @@ the `extfield F323` option. For example:
 server ntp.local minpoll 0 maxpoll 0 xleave extfield F323
 ----
 
+Since version 4.5, `chronyd` can apply corrections from PTP one-step end-to-end
+transparent clocks (e.g. network switches) to significantly improve accuracy of
+synchronisation in local networks. It requires the PTP transport to be enabled
+by the `ptpport` directive, HW timestamping, and the `extfield F324` option.
+For example:
+
+----
+server ntp.local minpoll -4 maxpoll -4 xleave extfield F323 extfield F324 port 319
+ptpport 319
+hwtimestamp eth0 minpoll -4
+----
+
 === Does `chronyd` have an ntpdate mode?
 
 Yes. With the `-q` option `chronyd` will set the system clock once and exit.

siv_gnutls.c

@@ -2,7 +2,7 @@
   chronyd/chronyc - Programs for keeping computer clocks accurate.
 
  **********************************************************************
- * Copyright (C) Miroslav Lichvar  2020
+ * Copyright (C) Miroslav Lichvar  2020, 2023
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of version 2 of the GNU General Public License as

socket.c

@@ -5,6 +5,7 @@
  * Copyright (C) Richard P. Curnow  1997-2003
  * Copyright (C) Timo Teras  2009
  * Copyright (C) Miroslav Lichvar  2009, 2013-2020
+ * Copyright (C) Luke Valenta  2023
  * 
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of version 2 of the GNU General Public License as

sources.c

@@ -174,6 +174,9 @@ static int selected_source_index; /* Which source index is currently
                                      if no current valid reference) */
 static int reported_no_majority;  /* Flag to avoid repeated log message
                                      about no majority */
+static int report_selection_loss; /* Flag to force logging a message if
+                                     selection is lost in a transient state
+                                     (SRC_WAITS_STATS, SRC_WAITS_UPDATE) */
 
 /* Score needed to replace the currently selected source */
 #define SCORE_LIMIT 10.0
@@ -201,6 +204,8 @@ static LOG_FileID logfileid;
 /* Forward prototype */
 
 static void update_sel_options(void);
+static void unselect_selected_source(LOG_Severity severity, const char *format,
+                                     const char *arg);
 static void slew_sources(struct timespec *raw, struct timespec *cooked, double dfreq,
                          double doffset, LCL_ChangeType change_type, void *anything);
 static void add_dispersion(double dispersion, void *anything);
@@ -314,12 +319,8 @@ void SRC_DestroyInstance(SRC_Instance instance)
   if (last_updated_inst == instance)
     last_updated_inst = NULL;
 
-  /* Force reselection if currently selected */
-  SRC_ResetInstance(instance);
-
   assert(initialised);
   if (instance->index < 0 || instance->index >= n_sources ||
-      instance->index == selected_source_index ||
       instance != sources[instance->index])
     assert(0);
 
@@ -336,6 +337,10 @@ void SRC_DestroyInstance(SRC_Instance instance)
 
   if (selected_source_index > dead_index)
     --selected_source_index;
+  else if (selected_source_index == dead_index)
+    unselect_selected_source(LOGS_INFO, NULL, NULL);
+
+  SRC_SelectSource(NULL);
 }
 
 /* ================================================== */
@@ -737,6 +742,26 @@ mark_ok_sources(SRC_Status status)
   }
 }
 
+/* ================================================== */
+/* Reset the index of selected source and report the selection loss.  If no
+   message is provided, assume it is a transient state and wait for another
+   call providing a message or selection of another source, which resets the
+   report_selection_loss flag. */
+
+static void
+unselect_selected_source(LOG_Severity severity, const char *format, const char *arg)
+{
+  if (selected_source_index != INVALID_SOURCE) {
+    selected_source_index = INVALID_SOURCE;
+    report_selection_loss = 1;
+  }
+
+  if (report_selection_loss && format) {
+    log_selection_message(severity, format, arg);
+    report_selection_loss = 0;
+  }
+}
+
 /* ================================================== */
 
 static int
@@ -854,9 +879,7 @@ SRC_SelectSource(SRC_Instance updated_inst)
   }
 
   if (n_sources == 0) {
-    /* Removed sources are unselected before actual removal */
+    unselect_selected_source(LOGS_INFO, "Can't synchronise: no sources", NULL);
-    if (selected_source_index != INVALID_SOURCE)
-      assert(0);
     return;
   }
 
@@ -1041,15 +1064,13 @@ SRC_SelectSource(SRC_Instance updated_inst)
   if (n_badstats_sources && n_sel_sources && selected_source_index == INVALID_SOURCE &&
       max_sel_reach_size < SOURCE_REACH_BITS && max_sel_reach >> 1 == max_badstat_reach) {
     mark_ok_sources(SRC_WAITS_STATS);
+    unselect_selected_source(LOGS_INFO, NULL, NULL);
     return;
   }
 
   if (n_endpoints == 0) {
     /* No sources provided valid endpoints */
-    if (selected_source_index != INVALID_SOURCE) {
+    unselect_selected_source(LOGS_INFO, "Can't synchronise: no selectable sources", NULL);
-      log_selection_message(LOGS_INFO, "Can't synchronise: no selectable sources", NULL);
-      selected_source_index = INVALID_SOURCE;
-    }
     return;
   }
 
@@ -1130,6 +1151,7 @@ SRC_SelectSource(SRC_Instance updated_inst)
     if (!reported_no_majority) {
       log_selection_message(LOGS_WARN, "Can't synchronise: no majority", NULL);
       reported_no_majority = 1;
+      report_selection_loss = 0;
     }
 
     if (selected_source_index != INVALID_SOURCE) {
@@ -1186,12 +1208,9 @@ SRC_SelectSource(SRC_Instance updated_inst)
   }
 
   if (!n_sel_sources || sel_req_source || n_sel_sources < CNF_GetMinSources()) {
-    if (selected_source_index != INVALID_SOURCE) {
+    unselect_selected_source(LOGS_INFO, "Can't synchronise: %s selectable sources",
-      log_selection_message(LOGS_INFO, "Can't synchronise: %s selectable sources",
                              !n_sel_sources ? "no" :
                              sel_req_source ? "no required source in" : "not enough");
-      selected_source_index = INVALID_SOURCE;
-    }
     mark_ok_sources(SRC_WAITS_SOURCES);
     return;
   }
@@ -1298,7 +1317,7 @@ SRC_SelectSource(SRC_Instance updated_inst)
     /* Before selecting the new synchronisation source wait until the reference
        can be updated */
     if (sources[max_score_index]->updates == 0) {
-      selected_source_index = INVALID_SOURCE;
+      unselect_selected_source(LOGS_INFO, NULL, NULL);
       mark_ok_sources(SRC_WAITS_UPDATE);
       return;
     }
@@ -1314,6 +1333,7 @@ SRC_SelectSource(SRC_Instance updated_inst)
     }
 
     reported_no_majority = 0;
+    report_selection_loss = 0;
   }
 
   mark_source(sources[selected_source_index], SRC_SELECTED);

test/unit/util.c

@@ -1,6 +1,6 @@
 /*
  **********************************************************************
- * Copyright (C) Miroslav Lichvar  2017-2018, 2021
+ * Copyright (C) Miroslav Lichvar  2017-2018, 2021, 2023
  * 
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of version 2 of the GNU General Public License as