Re: [lnf-log RFC PATCH 2/2] utils: take a example from libmnl and use nflog_nlmsg_parse

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

This code can be generalized a bit so you can place it in
src/nlmsg.c, see below.

On Mon, Aug 10, 2015 at 05:17:53PM +0900, Ken-ichirou MATSUZAWA wrote:
[...]
> +static struct nlmsghdr *
> +nflog_build_cfg_pf_request(char *buf, uint8_t command)
> +{
> +	struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
> +	nlh->nlmsg_type	= (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG;
> +	nlh->nlmsg_flags = NLM_F_REQUEST;
> +
> +	struct nfgenmsg *nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
> +	nfg->nfgen_family = AF_INET;
> +	nfg->version = NFNETLINK_V0;
> +
> +	struct nfulnl_msg_config_cmd cmd = {
> +		.command = command,
> +	};
> +	mnl_attr_put(nlh, NFULA_CFG_CMD, sizeof(cmd), &cmd);
> +
> +	return nlh;
> +}

I suggest you use and implement the following new helper functions for
libnetfilter_log:

struct nlmsghdr *
nfnl_nlmsg_put_header(char *buf, uint8_t type, uint8_t cmd, uint16_t qnum);

int nfnl_attr_put_cfg_mode(struct nlmsghdr *nlh, struct nfulnl_msg_config_mode *mode);
int nfnl_attr_put_cfg_cmd(struct nlmsghdr *nlh, struct nfulnl_msg_config_cmd *cmd);

You can reuse code in the functions here below to make it. Thanks.

> +static struct nlmsghdr *
> +nflog_build_cfg_request(char *buf, uint8_t command, int qnum)
> +{
> +	struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
> +	nlh->nlmsg_type	= (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG;
> +	nlh->nlmsg_flags = NLM_F_REQUEST;
> +
> +	struct nfgenmsg *nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
> +	nfg->nfgen_family = AF_INET;
> +	nfg->version = NFNETLINK_V0;
> +	nfg->res_id = htons(qnum);
> +
> +	struct nfulnl_msg_config_cmd cmd = {
> +		.command = command,
> +	};
> +	mnl_attr_put(nlh, NFULA_CFG_CMD, sizeof(cmd), &cmd);
> +
> +	return nlh;
> +}
> +
> +static struct nlmsghdr *
> +nflog_build_cfg_params(char *buf, uint8_t mode, int range, int qnum)
> +{
> +	struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
> +	nlh->nlmsg_type	= (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG;
> +	nlh->nlmsg_flags = NLM_F_REQUEST;
> +
> +	struct nfgenmsg *nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
> +	nfg->nfgen_family = AF_UNSPEC;
> +	nfg->version = NFNETLINK_V0;
> +	nfg->res_id = htons(qnum);
> +
> +	struct nfulnl_msg_config_mode params = {
> +		.copy_range = htonl(range),
> +		.copy_mode = mode,
> +	};
> +	mnl_attr_put(nlh, NFULA_CFG_MODE, sizeof(params), &params);
> +
> +	return nlh;
> +}
> +
[...]