About Bind Plugin development

[Chunhui Ouyang]

Strangely, if I don't use config.h, I get a whole bunch of compilation errors, such as:

```
gcc -shared -fPIC -I /root/bind-project/lib/isc/include/ -I /root/bind-project/bind/lib/isccfg/include/ -I /root/bind-project/bind/lib/ns/include/ main.c -o filter-plugin.so
In file included from /usr/include/isc/quota.h:34,
                 from /root/bind-project/bind/lib/ns/include/ns/client.h:65,
                 from main.c:15:
/usr/include/isc/job.h:40:38: error: field ‘wfcq_node’ has incomplete type
   40 |                 struct cds_wfcq_node wfcq_node;
      |                                      ^~~~~~~~~
In file included from /usr/include/isc/mutex.h:24,
                 from /usr/include/isc/mem.h:23,
                 from /usr/include/isc/buffer.h:112,
                 from main.c:5:
/usr/include/isc/quota.h:59:1: error: invalid application of ‘sizeof’ to incomplete type ‘struct __cds_wfcq_head’
   59 | STATIC_ASSERT(ISC_OS_CACHELINE_SIZE >= sizeof(struct __cds_wfcq_head),
      | ^~~~~~~~~~~~~
/usr/include/isc/quota.h:59:15: error: expression in static assertion is not an integer
   59 | STATIC_ASSERT(ISC_OS_CACHELINE_SIZE >= sizeof(struct __cds_wfcq_head),
      |               ^~~~~~~~~~~~~~~~~~~~~
/usr/include/isc/quota.h:68:38: error: field ‘head’ has incomplete type
   68 |                 struct cds_wfcq_head head;
      |                                      ^~~~
/usr/include/isc/quota.h:70:47: error: invalid application of ‘sizeof’ to incomplete type ‘struct __cds_wfcq_head’
   70 |                                        sizeof(struct __cds_wfcq_head)];
      |                                               ^~~~~~
/usr/include/isc/quota.h:71:38: error: field ‘tail’ has incomplete type
   71 |                 struct cds_wfcq_tail tail;
      |                                      ^~~~
In file included from /root/bind-project/bind/lib/ns/include/ns/client.h:68:
/usr/include/dns/db.h:234:33: error: field ‘rcu_head’ has incomplete type
  234 |         struct rcu_head         rcu_head;
      |                                 ^~~~~~~~
make: *** [Makefile:11: filter-plugin.so] Error 1
```

* Ondřej Surý <ondrej at isc.org> [2025-11-22 :32:13]:

> We don’t guidelines for out of tree plugins, but you should not need config.h from the build. The plugin just need to export the needed symbols.
> 
> You can contribute these guidelines (or more plugin hooks if needed), this is open source after all…
> 
> Ondrej
> --
> Ondřej Surý — ISC (He/Him)
> 
> My working hours and your working hours may be different. Please do not feel obligated to reply outside your normal working hours.
> 
> > On 22. 11. 2025, at 11:51, Chunhui Ouyang <jack9603301 at 163.com> wrote:
> > 
> > Hello, could you provide a guide on how to organize the project structure for third-party plugin development? I've noticed that current compilation requires the already built bind9's config.h file, but this file doesn't exist in a brand new project. Does this mean it doesn't allow external compilation of the source code?
> > 
> > Looking forward to your reply.
> > 
> > * Colin Vidal <colin at isc.org> [2025-11-21 :14:06]:
> > 
> >>> On Fri, 2025-11-21 at 23:29 +0800, Chunhui Ouyang wrote:
> >>> Could you tell me what the entry point of the plugin is?
> >>> 
> >> 
> >> As explained in the reference for plugin development I sent you
> >> earlier:
> >> 
> >> "At various locations within the named source code, there are "hook
> >> points" at which a plugin may register itself. When a hook point is
> >> reached while named is running, it is checked to see whether any
> >> plugins have registered themselves there; if so, the associated "hook
> >> action" - a function within the plugin library - is called."
> >> 
> >> So there is no really a single "entry" point, but rather multiples ones
> >> depending where the plugin is hooked. (Plus the four `plugin_*` API to
> >> implement for registering, etc.)
> >> 
> >> Side note: please answer emails with the mailing list in CC, so
> >> everyone can see, benefit and contribute to this thread.
> >> 
> >> Thanks
> >> 
> >> Colin Vidal
> >> 
> > --
> > Visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list.
> > <signature.asc>
> 
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