Re: [libvirt] [PATCH V5 06/10] Extend the filter XML to support priorities of chains
On 11/17/2011 06:15 PM, Eric Blake wrote:
On 11/17/2011 01:11 PM, Stefan Berger wrote:
> This patch extends the filter XML to support priorities of chains
> in the XML. An example would be:
>
> <filter name='allow-arpxyz' chain='arp-xyz'
priority='200'>
> [...]
> </filter>
>
> The permitted values for priorities are [-1000, 1000].
> By setting the pririty of a chain the order in which it is accessed
> from the interface root chain can be influenced.
>
> Signed-off-by: Stefan Berger<stefanb(a)linux.vnet.ibm.com>
>
> ---
> docs/schemas/nwfilter.rng | 7 ++++++-
Missing documentation in docs/formatnwfilter.html.in. I'll live up to
my hard-line reputation on this one, and request a v6 with documentation
(for example, it's worth documenting whether priority 100 is accessed
before or after priority 200).
I have such a patch much further down the queue. I'll pull the relevant
parts into v6.
But as to the code...
> @@ -2028,6 +2030,26 @@ virNWFilterDefParseXML(xmlXPathContextPt
> goto cleanup;
> }
>
> + chain_pri_s = virXPathString("string(./@priority)", ctxt);
> + if (chain_pri_s) {
> + if (sscanf(chain_pri_s, "%d",&chain_priority) != 1) {
Let's use virStrToLong_i() instead of sscanf(); much nicer on the error
handling aspect.
Done.
> @@ -2036,11 +2058,16 @@ virNWFilterDefParseXML(xmlXPathContextPt
> goto cleanup;
> }
> ret->chainsuffix = chain;
> - /* assign an implicit priority -- support XML attribute later */
> - if (intMapGetByString(chain_priorities, chain, 0,
> -&ret->chainPriority) == false) {
> - ret->chainPriority = (NWFILTER_MAX_FILTER_PRIORITY +
> - NWFILTER_MIN_FILTER_PRIORITY) / 2;
> +
> + if (chain_pri_s) {
> + ret->chainPriority = chain_priority;
> + } else {
> + /* assign an implicit priority -- support XML attribute later */
Is this comment still accurate, now that you have an XML attribute?
Fixed.
> @@ -2852,6 +2881,9 @@ virNWFilterDefFormat(virNWFilterDefPtr d
> virBufferAsprintf(&buf, "<filter name='%s'
chain='%s'",
> def->name,
> def->chainsuffix);
> + if (def->chainPriority != 0)
> + virBufferAsprintf(&buf, " priority='%d'",
> + def->chainPriority);
That means an explicit pririoty='0' by the user is eaten and does not
appear on the output. But that's not too bad, and as long as we
document that priority is 0 unless explicitly specified, we're covered
(hence my plea for documentation...)
Everything else looks okay.