Re: [libnftnl PATCH 1/2] src: add flag to add event wrapping in output functions

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Apr 15, 2014 at 02:50:30PM +0200, Arturo Borrero Gonzalez wrote:
> diff --git a/src/chain.c b/src/chain.c
> index 472203e..87558a1 100644
> --- a/src/chain.c
> +++ b/src/chain.c
> @@ -924,17 +924,44 @@ static int nft_chain_snprintf_default(char *buf, size_t size,
>  int nft_chain_snprintf(char *buf, size_t size, struct nft_chain *c,
>  		       uint32_t type, uint32_t flags)
>  {
> +	int ret, len = size, offset = 0;
> +
> +	if (flags & (1 << NFT_OUTPUT_FLAG_EVENTNEW)) {
> +		ret = snprintf(buf+offset, len, "%s",
> +			       nft_event_opentag(NFT_OUTPUT_FLAG_EVENTNEW,
> +						 type));
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +	} else if (flags & (1 << NFT_OUTPUT_FLAG_EVENTDEL)) {
> +		ret = snprintf(buf+offset, len, "%s",
> +			       nft_event_opentag(NFT_OUTPUT_FLAG_EVENTDEL,
> +						 type));
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +	}
> +
[...]
> +	if (flags & (1 << NFT_OUTPUT_FLAG_EVENTNEW)) {
> +		ret = snprintf(buf+offset, len, "%s",
> +			       nft_event_opentag(NFT_OUTPUT_FLAG_EVENTNEW,
> +						 type));
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +		noevent_flags &= ~(1 << NFT_OUTPUT_FLAG_EVENTNEW);
> +	} else if (flags & (1 << NFT_OUTPUT_FLAG_EVENTDEL)) {
> +		ret = snprintf(buf+offset, len, "%s",
> +			       nft_event_opentag(NFT_OUTPUT_FLAG_EVENTDEL,
> +						 type));
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +		noevent_flags &= ~(1 << NFT_OUTPUT_FLAG_EVENTDEL);
> +	}

This code looks very similar, you can encapsulate it in one function
to add the heading and the trailer.

Regarding the noevent_flags thing, which is the only different, you can do:

        unsigned int inner_flags &= ~NFT_OF_EVENT_ANY;

And use inner_flags to when you have nested calls (ie. like in ruleset.c).

The NFT_OF_EVENT_ANY mask should be something like:

enum ... {
        NFT_OF_EVENT_ANY        = (NFT_OF_EVENT_NEW | NFT_OF_EVENT_DEL)
};

Thanks.