How to add options to ntpd

Question

I'd like to add a new option to ntpd however I couldn't find how to generate ntpd/ntpd-opts{.c, .h} after adding some lines to ntpd/ntpdbase-opts.def e.g.,

$ git diff ntpd/ntpdbase-opts.def
diff --git a/ntpd/ntpdbase-opts.def b/ntpd/ntpdbase-opts.def
index 66b953528..a790cbd51 100644
--- a/ntpd/ntpdbase-opts.def
+++ b/ntpd/ntpdbase-opts.def
@@ -479,3 +479,13 @@ flag = {
        the server to be discovered via mDNS client lookup.
        _EndOfDoc_;
 };
+
+flag = {
+    name      = foo;
+    value     = F;
+    arg-type  = number;
+    descrip   = "Some new option";
+    doc = <<-  _EndOfDoc_
+       For testing purpose only.
+       _EndOfDoc_;
+};

Do you have any ideas?

Answer 1

how to generate ntpd/ntpd-opts{.c, .h} after adding some lines to ntpd/ntpdbase-opts.def

It is just in build scripts. Just compile https://github.com/ntp-project/ntp/blob/master-no-authorname/INSTALL#L30 it normally and make will pick it up.

https://github.com/ntp-project/ntp/blob/master-no-authorname/ntpd/Makefile.am#L304

https://github.com/ntp-project/ntp/blob/master-no-authorname/ntpd/Makefile.am#L183

Answer 2

In addition to @KamilCuk's answer, we need to do the following to add custom options:

1. Edit *.def file
2. Run bootstrap script
3. Run configure script with --disable-local-libopts option
4. Run make

For example,

$ git diff ntpd/ntpdbase-opts.def
diff --git a/ntpd/ntpdbase-opts.def b/ntpd/ntpdbase-opts.def
index 66b953528..a790cbd51 100644
--- a/ntpd/ntpdbase-opts.def
+++ b/ntpd/ntpdbase-opts.def
@@ -479,3 +479,13 @@ flag = {
        the server to be discovered via mDNS client lookup.
        _EndOfDoc_;
 };
+
+flag = {
+    name      = foo;
+    value     = F;
+    arg-type  = number;
+    descrip   = "Some new option";
+    doc = <<-  _EndOfDoc_
+       For testing purpose only.
+       _EndOfDoc_;
+};

This change yields:

$ ./ntpd --help
ntpd - NTP daemon program - Ver. 4.2.8p15
Usage:  ntpd [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \
                [ <server1> ... <serverN> ]
  Flg Arg Option-Name    Description
   -4 no  ipv4           Force IPv4 DNS name resolution
                                - prohibits the option 'ipv6'
   ...
   -F Num foo            Some new option
      opt version        output version information and exit
   -? no  help           display extended usage information and exit
   -! no  more-help      extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
...