client: add option to print original names

Add -N option to chronyc to print the original names by which the
sources were specified instead of using reverse DNS lookup. The option
works in the sources, sourcestats and tracking commands.

client.c

@@ -72,6 +72,8 @@ static int on_terminal = 0;
 
 static int no_dns = 0;
 
+static int source_names = 0;
+
 static int csv_mode = 0;
 
 /* ================================================== */
@@ -2022,12 +2024,40 @@ print_info_field(const char *format, ...)
 
 /* ================================================== */
 
+static int
+get_source_name(IPAddr *ip_addr, char *buf, int size)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  int i;
+
+  request.command = htons(REQ_NTP_SOURCE_NAME);
+  UTI_IPHostToNetwork(ip_addr, &request.data.ntp_source_name.ip_addr);
+  if (!request_reply(&request, &reply, RPY_NTP_SOURCE_NAME, 0) ||
+      reply.data.ntp_source_name.name[sizeof (reply.data.ntp_source_name.name) - 1] != '\0' ||
+      snprintf(buf, size, "%s", reply.data.ntp_source_name.name) >= size)
+    return 0;
+
+  /* Make sure the name is printable */
+  for (i = 0; i < size && buf[i] != '\0'; i++) {
+    if (!isgraph(buf[i]))
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
 static void
 format_name(char *buf, int size, int trunc_dns, int ref, uint32_t ref_id,
-            IPAddr *ip_addr)
+            int source, IPAddr *ip_addr)
 {
   if (ref) {
     snprintf(buf, size, "%s", UTI_RefidToString(ref_id));
+  } else if (source && source_names) {
+    if (!get_source_name(ip_addr, buf, size))
+      snprintf(buf, size, "?");
   } else if (no_dns || csv_mode) {
     snprintf(buf, size, "%s", UTI_IPToString(ip_addr));
   } else {
@@ -2058,7 +2088,7 @@ process_cmd_sources(char *line)
   CMD_Reply reply;
   IPAddr ip_addr;
   uint32_t i, mode, n_sources;
-  char name[50], mode_ch, state_ch;
+  char name[256], mode_ch, state_ch;
   int verbose;
 
   /* Check whether to output verbose headers */
@@ -2097,7 +2127,7 @@ process_cmd_sources(char *line)
     UTI_IPNetworkToHost(&reply.data.source_data.ip_addr, &ip_addr);
     format_name(name, sizeof (name), 25,
                 mode == RPY_SD_MD_REF && ip_addr.family == IPADDR_INET4,
-                ip_addr.addr.in4, &ip_addr);
+                ip_addr.addr.in4, 1, &ip_addr);
 
     switch (mode) {
       case RPY_SD_MD_CLIENT:
@@ -2165,7 +2195,7 @@ process_cmd_sourcestats(char *line)
   CMD_Reply reply;
   uint32_t i, n_sources;
   int verbose = 0;
-  char name[50];
+  char name[256];
   IPAddr ip_addr;
 
   verbose = check_for_verbose_flag(line);
@@ -2201,7 +2231,7 @@ process_cmd_sourcestats(char *line)
 
     UTI_IPNetworkToHost(&reply.data.sourcestats.ip_addr, &ip_addr);
     format_name(name, sizeof (name), 25, ip_addr.family == IPADDR_UNSPEC,
-                ntohl(reply.data.sourcestats.ref_id), &ip_addr);
+                ntohl(reply.data.sourcestats.ref_id), 1, &ip_addr);
 
     print_report("%-25s %3U %3U  %I %+P %P  %+S  %S\n",
                  name,
@@ -2227,7 +2257,7 @@ process_cmd_tracking(char *line)
   CMD_Reply reply;
   IPAddr ip_addr;
   uint32_t ref_id;
-  char name[50];
+  char name[256];
   struct timespec ref_time;
   
   request.command = htons(REQ_TRACKING);
@@ -2238,7 +2268,7 @@ process_cmd_tracking(char *line)
 
   UTI_IPNetworkToHost(&reply.data.tracking.ip_addr, &ip_addr);
   format_name(name, sizeof (name), sizeof (name),
-              ip_addr.family == IPADDR_UNSPEC, ref_id, &ip_addr);
+              ip_addr.family == IPADDR_UNSPEC, ref_id, 1, &ip_addr);
 
   UTI_TimespecNetworkToHost(&reply.data.tracking.ref_time, &ref_time);
 
@@ -2534,7 +2564,7 @@ process_cmd_clients(char *line)
       if (ip.family == IPADDR_UNSPEC)
         continue;
 
-      format_name(name, sizeof (name), 25, 0, 0, &ip);
+      format_name(name, sizeof (name), 25, 0, 0, 0, &ip);
 
       print_report("%-25s  %6U  %5U  %C  %C  %I  %6U  %5U  %C  %I\n",
                    name,
@@ -3164,7 +3194,7 @@ display_gpl(void)
 static void
 print_help(const char *progname)
 {
-      printf("Usage: %s [-h HOST] [-p PORT] [-n] [-c] [-d] [-4|-6] [-m] [COMMAND]\n",
+      printf("Usage: %s [-h HOST] [-p PORT] [-n] [-N] [-c] [-d] [-4|-6] [-m] [COMMAND]\n",
              progname);
 }
 
@@ -3201,7 +3231,7 @@ main(int argc, char **argv)
   optind = 1;
 
   /* Parse short command-line options */
-  while ((opt = getopt(argc, argv, "+46acdf:h:mnp:v")) != -1) {
+  while ((opt = getopt(argc, argv, "+46acdf:h:mnNp:v")) != -1) {
     switch (opt) {
       case '4':
       case '6':
@@ -3228,6 +3258,9 @@ main(int argc, char **argv)
       case 'n':
         no_dns = 1;
         break;
+      case 'N':
+        source_names = 1;
+        break;
       case 'p':
         port = atoi(optarg);
         break;

doc/chronyc.adoc

@@ -78,11 +78,18 @@ With this option hostnames will be resolved only to IPv6 addresses.
 This option disables resolving of IP addresses to hostnames, e.g. to avoid slow
 DNS lookups. Long addresses will not be truncated to fit into the column.
 
+*-N*::
+This option enables printing of the original names of NTP sources that were
+specified in the configuration file, or *chronyc* commands, and are internally
+used by *chronyd*. Without the *-n* and *-N* option, the names of NTP sources
+are obtained from reverse DNS lookups and can be different from the original
+names.
+
 *-c*::
 This option enables printing of reports in a comma-separated values (CSV)
-format. IP addresses will not be resolved to hostnames, time will be printed as
-number of seconds since the epoch and values in seconds will not be converted
-to other units.
+format. Reverse DNS lookups will be disabled, time will be printed as number of
+seconds since the epoch, and values in seconds will not be converted to other
+units.
 
 *-d*::
 This option enables printing of debugging messages if *chronyc* was compiled