Re: [PATCH xtables-nft 1/3] xtables-monitor: fix rule printing

[Phil Sutter <phil@nwl.cc>]

On Sat, Dec 12, 2020 at 04:15:32PM +0100, Florian Westphal wrote:
> trace_print_rule does a rule dump.  This prints unrelated rules
> in the same chain.  Instead the function should only request the
> specific handle.
> 
> Furthermore, flush output buffer afterwards so this plays nice when
> output isn't a terminal.
> 
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>  iptables/xtables-monitor.c | 32 +++++++++++++++-----------------
>  1 file changed, 15 insertions(+), 17 deletions(-)
> 
> diff --git a/iptables/xtables-monitor.c b/iptables/xtables-monitor.c
> index 4008cc00d469..364e600e1b38 100644
> --- a/iptables/xtables-monitor.c
> +++ b/iptables/xtables-monitor.c
> @@ -227,12 +227,12 @@ static void trace_print_rule(const struct nftnl_trace *nlt, struct cb_arg *args)
>  		exit(EXIT_FAILURE);
>  	}
>  
> -	nlh = nftnl_chain_nlmsg_build_hdr(buf, NFT_MSG_GETRULE, family, NLM_F_DUMP, 0);
> +	nlh = nftnl_chain_nlmsg_build_hdr(buf, NFT_MSG_GETRULE, family, 0, 0);
>  
>          nftnl_rule_set_u32(r, NFTNL_RULE_FAMILY, family);
>  	nftnl_rule_set_str(r, NFTNL_RULE_CHAIN, chain);
>  	nftnl_rule_set_str(r, NFTNL_RULE_TABLE, table);
> -	nftnl_rule_set_u64(r, NFTNL_RULE_POSITION, handle);
> +	nftnl_rule_set_u64(r, NFTNL_RULE_HANDLE, handle);
>  	nftnl_rule_nlmsg_build_payload(nlh, r);
>  	nftnl_rule_free(r);
>  
> @@ -248,24 +248,21 @@ static void trace_print_rule(const struct nftnl_trace *nlt, struct cb_arg *args)
>  	}
>  
>  	portid = mnl_socket_get_portid(nl);
> -        if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
> -                perror("mnl_socket_send");
> -                exit(EXIT_FAILURE);
> -        }
> +	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
> +		perror("mnl_socket_send");
> +		exit(EXIT_FAILURE);
> +	}

Just in case someone else wonders as well: This does a whitespace
cleanup, replacing spaces by tabs. Later changes contain the same
cleanup, too.

Cheers, Phil