conntrackd: generalize file descriptor infrastructure

This patch generalizes the select-based file descriptor infrastructure
by allowing you to register file descriptors and its callbacks. Instead
of hardcoding the descriptors that needs to be checked.

Now, struct fds_item contains a callback and pointer to data that is
passed to it:

  struct fds_item {
         struct list_head        head;
         int                     fd;
 +       void                    (*cb)(void *data);
 +       void                    *data;
  };

Then, we check which ones are active in the select_main_step() function:

 list_for_each_entry(cur, &STATE(fds)->list, head) {
         if (FD_ISSET(cur->fd, &readfds))
                 cur->cb(cur->data);
 }

And it invoked the corresponding callback.

I had to slightly modify the channel infrastructure to fit it into
the changes.

This modularity is required for the upcoming cthelper support.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/channel.c b/src/channel.c
index 818bb01..8b7c319 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -310,3 +310,8 @@ int channel_accept(struct channel *c)
 {
 	return c->ops->accept(c);
 }
+
+int channel_type(struct channel *c)
+{
+	return c->ops->type;
+}