Re: [RFC] ematch API, u32 ematch, nbyte ematch, basic classifier

* jamal [ref] 2005-01-04 08:19

On Tue, 2005-01-04 at 07:03, Thomas Graf wrote:

quoted

 change() (Optional)

My thinking is:
It doesnt have to be simple 32 bit data.
If i pass you a struct and tell you what length it is, then you as the
classifier dont know need to know anything about it. You just store
mystruct as data and datalen from the TLV. you then pass the datastruct
to match() -  Of course the match() will have to know what that struct
means.

That's exactly how it is, basically the logic is:

	if (ops->change) {
		err = ops->change(tp, data, datalen, m);
		if (err < 0)
			goto errout;
	} else if (datalen > 0) {
		if (mh->flags & TCF_EM_SIMPLE) {
			if (datalen != sizeof(u32))
				goto errout;
			m->data = *(u32 *) data;
		} else {
			void *v = kmalloc(datalen, GFP_KERNEL);
			if (v == NULL) {
				err = -ENOBUFS;
				goto errout;
			}
			memcpy(v, data, datalen);
			m->data = (unsigned long) v;
		}
	}
	m->datalen = datalen;

quoted

 destroy() (Optional)
   Called if provided, otheriwse m->data is freed in ematch api unless
   TCF_EM_SIMPLE is set.

Again using the above logic, destroy becomes just kfree(mystruct)

Right, that's exactly how it is

	if (m->ops->destroy)
		m->ops->destroy(tp, m);
	else if (!(m->hdr.flags & TCF_EM_SIMPLE) && m->data)
		kfree((void *) m->data);

quoted

 dump() (Optional)
   Called if provided, otherwise m->data is dumped onto the skb with
   m->datalen as L. Special handling again for TCF_EM_SIMPLE.

and dump becomes a matter of looking at datalen and encapsulating
mystruct in a TLV without thinking about what the content is.

Absolutely true, you know about the code before you read it ;->

	if (m->ops->dump) {
		if (m->ops->dump(skb, m) < 0)
			goto rtattr_failure;
	} else if (m->hdr.flags & TCF_EM_SIMPLE) {
		u32 u = m->data;
		RTA_PUT_NOHDR(skb, sizeof(u32), &u);
	} else if (m->datalen > 0)
		RTA_PUT_NOHDR(skb, m->datalen, (void *) m->data);