#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include "libnetlink.h"

#include "ssfilter.h"

#include "ss_util.h"

static int dummy_filter(struct nlmsghdr *n, void *arg)

{

	/* just stops rtnl_dump_filter() */

	return -1;

}

static bool cgroup_filter_check(void)

{

	struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };

	DIAG_REQUEST(req, struct inet_diag_req_v2 r);

	struct instr {

		struct inet_diag_bc_op op;

		__u64 cgroup_id;

	} __attribute__((packed));

	int inslen = sizeof(struct instr);

	struct instr instr = {

		{ INET_DIAG_BC_CGROUP_COND, inslen, inslen + 4 },

		0

	};

	struct rtnl_handle rth;

	struct iovec iov[3];

	struct msghdr msg;

	struct rtattr rta;

	int ret = false;

	int iovlen = 3;

	if (rtnl_open_byproto(&rth, 0, NETLINK_SOCK_DIAG))

		return false;

	rth.dump = MAGIC_SEQ;

	rth.flags = RTNL_HANDLE_F_SUPPRESS_NLERR;

	memset(&req.r, 0, sizeof(req.r));

	req.r.sdiag_family = AF_INET;

	req.r.sdiag_protocol = IPPROTO_TCP;

	req.nlh.nlmsg_len += RTA_LENGTH(inslen);

	rta.rta_type = INET_DIAG_REQ_BYTECODE;

	rta.rta_len = RTA_LENGTH(inslen);

	iov[0] = (struct iovec) { &req, sizeof(req) };

	iov[1] = (struct iovec) { &rta, sizeof(rta) };

	iov[2] = (struct iovec) { &instr, inslen };

	msg = (struct msghdr) {

		.msg_name = (void *)&nladdr,

		.msg_namelen = sizeof(nladdr),

		.msg_iov = iov,

		.msg_iovlen = iovlen,

	};

	if (sendmsg(rth.fd, &msg, 0) < 0)

		goto out;

	if (rtnl_dump_filter(&rth, dummy_filter, NULL) < 0) {

		ret = (errno != EINVAL);

		goto out;

	}

	ret = true;

out:

	rtnl_close(&rth);

	return ret;

}

struct filter_check_t {

	bool (*check)(void);

	int checked:1,

	    supported:1;

};

static struct filter_check_t filter_checks[SSF__MAX] = {

	[SSF_CGROUPCOND] = { cgroup_filter_check, 0 },

};

bool ssfilter_is_supported(int type)

{

	struct filter_check_t f;

	if (type >= SSF__MAX)

		return false;

	f = filter_checks[type];

	if (!f.check)

		return true;

	if (!f.checked) {

		f.supported = f.check();

		f.checked = 1;

	}

	return f.supported;

}