/*
 * Copyright (c) 2016 Anders K. Pedersen <akp@cohaesio.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <arpa/inet.h>
#include <errno.h>
#include <linux/netfilter/nf_tables.h>

#include "internal.h"
#include <libmnl/libmnl.h>
#include <libnftnl/expr.h>
#include <libnftnl/rule.h>

#ifndef NFT_RT_MAX
#define NFT_RT_MAX (NFT_RT_TCPMSS + 1)
#endif

struct nftnl_expr_rt {
	enum nft_rt_keys	key;
	enum nft_registers	dreg;
};

static int
nftnl_expr_rt_set(struct nftnl_expr *e, uint16_t type,
		       const void *data, uint32_t data_len)
{
	struct nftnl_expr_rt *rt = nftnl_expr_data(e);

	switch (type) {
	case NFTNL_EXPR_RT_KEY:
		rt->key = *((uint32_t *)data);
		break;
	case NFTNL_EXPR_RT_DREG:
		rt->dreg = *((uint32_t *)data);
		break;
	default:
		return -1;
	}
	return 0;
}

static const void *
nftnl_expr_rt_get(const struct nftnl_expr *e, uint16_t type,
		       uint32_t *data_len)
{
	struct nftnl_expr_rt *rt = nftnl_expr_data(e);

	switch (type) {
	case NFTNL_EXPR_RT_KEY:
		*data_len = sizeof(rt->key);
		return &rt->key;
	case NFTNL_EXPR_RT_DREG:
		*data_len = sizeof(rt->dreg);
		return &rt->dreg;
	}
	return NULL;
}

static int nftnl_expr_rt_cb(const struct nlattr *attr, void *data)
{
	const struct nlattr **tb = data;
	int type = mnl_attr_get_type(attr);

	if (mnl_attr_type_valid(attr, NFTA_RT_MAX) < 0)
		return MNL_CB_OK;

	switch (type) {
	case NFTA_RT_KEY:
	case NFTA_RT_DREG:
		if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
			abi_breakage();
		break;
	}

	tb[type] = attr;
	return MNL_CB_OK;
}

static void
nftnl_expr_rt_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
{
	struct nftnl_expr_rt *rt = nftnl_expr_data(e);

	if (e->flags & (1 << NFTNL_EXPR_RT_KEY))
		mnl_attr_put_u32(nlh, NFTA_RT_KEY, htonl(rt->key));
	if (e->flags & (1 << NFTNL_EXPR_RT_DREG))
		mnl_attr_put_u32(nlh, NFTA_RT_DREG, htonl(rt->dreg));
}

static int
nftnl_expr_rt_parse(struct nftnl_expr *e, struct nlattr *attr)
{
	struct nftnl_expr_rt *rt = nftnl_expr_data(e);
	struct nlattr *tb[NFTA_RT_MAX+1] = {};

	if (mnl_attr_parse_nested(attr, nftnl_expr_rt_cb, tb) < 0)
		return -1;

	if (tb[NFTA_RT_KEY]) {
		rt->key = ntohl(mnl_attr_get_u32(tb[NFTA_RT_KEY]));
		e->flags |= (1 << NFTNL_EXPR_RT_KEY);
	}
	if (tb[NFTA_RT_DREG]) {
		rt->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_RT_DREG]));
		e->flags |= (1 << NFTNL_EXPR_RT_DREG);
	}

	return 0;
}

static const char *rt_key2str_array[NFT_RT_MAX] = {
	[NFT_RT_CLASSID]	= "classid",
	[NFT_RT_NEXTHOP4]	= "nexthop4",
	[NFT_RT_NEXTHOP6]	= "nexthop6",
	[NFT_RT_TCPMSS]		= "tcpmss",
};

static const char *rt_key2str(uint8_t key)
{
	if (key < NFT_RT_MAX)
		return rt_key2str_array[key];

	return "unknown";
}

static inline int str2rt_key(const char *str)
{
	int i;

	for (i = 0; i < NFT_RT_MAX; i++) {
		if (strcmp(str, rt_key2str_array[i]) == 0)
			return i;
	}

	errno = EINVAL;
	return -1;
}

static int nftnl_expr_rt_json_parse(struct nftnl_expr *e, json_t *root,
				    struct nftnl_parse_err *err)
{
#ifdef JSON_PARSING
	const char *val_str;
	uint32_t reg;
	int val32;

	val_str = nftnl_jansson_parse_str(root, "key", err);
	if (val_str != NULL) {
		val32 = str2rt_key(val_str);
		if (val32 >= 0)
			nftnl_expr_set_u32(e, NFTNL_EXPR_RT_KEY, val32);
	}

	if (nftnl_jansson_node_exist(root, "dreg")) {
		if (nftnl_jansson_parse_reg(root, "dreg", NFTNL_TYPE_U32, &reg,
					  err) == 0)
			nftnl_expr_set_u32(e, NFTNL_EXPR_RT_DREG, reg);
	}

	return 0;
#else
	errno = EOPNOTSUPP;
	return -1;
#endif
}

static int
nftnl_expr_rt_snprintf_default(char *buf, size_t len,
			       const struct nftnl_expr *e)
{
	struct nftnl_expr_rt *rt = nftnl_expr_data(e);

	if (e->flags & (1 << NFTNL_EXPR_RT_DREG)) {
		return snprintf(buf, len, "load %s => reg %u ",
				rt_key2str(rt->key), rt->dreg);
	}
	return 0;
}

static int nftnl_expr_rt_export(char *buf, size_t size,
				  const struct nftnl_expr *e, int type)
{
	struct nftnl_expr_rt *rt = nftnl_expr_data(e);
	NFTNL_BUF_INIT(b, buf, size);

	if (e->flags & (1 << NFTNL_EXPR_RT_DREG))
		nftnl_buf_u32(&b, type, rt->dreg, DREG);
	if (e->flags & (1 << NFTNL_EXPR_RT_KEY))
		nftnl_buf_str(&b, type, rt_key2str(rt->key), KEY);

	return nftnl_buf_done(&b);
}

static int
nftnl_expr_rt_snprintf(char *buf, size_t len, uint32_t type,
		       uint32_t flags, const struct nftnl_expr *e)
{
	switch (type) {
	case NFTNL_OUTPUT_DEFAULT:
		return nftnl_expr_rt_snprintf_default(buf, len, e);
	case NFTNL_OUTPUT_XML:
	case NFTNL_OUTPUT_JSON:
		return nftnl_expr_rt_export(buf, len, e, type);
	default:
		break;
	}
	return -1;
}

static bool nftnl_expr_rt_cmp(const struct nftnl_expr *e1,
			      const struct nftnl_expr *e2)
{
	struct nftnl_expr_rt *r1 = nftnl_expr_data(e1);
	struct nftnl_expr_rt *r2 = nftnl_expr_data(e2);
	bool eq = true;

	if (e1->flags & (1 << NFTNL_EXPR_RT_KEY))
		eq &= (r1->key == r2->key);
	if (e1->flags & (1 << NFTNL_EXPR_RT_DREG))
		eq &= (r1->dreg == r2->dreg);

	return eq;
}

struct expr_ops expr_ops_rt = {
	.name		= "rt",
	.alloc_len	= sizeof(struct nftnl_expr_rt),
	.max_attr	= NFTA_RT_MAX,
	.cmp		= nftnl_expr_rt_cmp,
	.set		= nftnl_expr_rt_set,
	.get		= nftnl_expr_rt_get,
	.parse		= nftnl_expr_rt_parse,
	.build		= nftnl_expr_rt_build,
	.snprintf	= nftnl_expr_rt_snprintf,
	.json_parse	= nftnl_expr_rt_json_parse,
};