/*
 * Copyright (c) 2008-2012 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <arpa/inet.h>

#include <libnftnl/udata.h>

#include <rule.h>
#include <expression.h>
#include <gmputil.h>
#include <utils.h>

static enum byteorder get_key_byteorder(const struct expr *e)
{
	enum datatypes basetype = expr_basetype(e)->type;

	switch (basetype) {
	case TYPE_INTEGER:
		/* For ranges, integers MUST be in BYTEORDER_BIG_ENDIAN.
		 * If the LHS (lookup key, e.g. 'meta mark', is host endian,
		 * a byteorder expression is injected to convert the register
		 * content before lookup.
		 */
		return BYTEORDER_BIG_ENDIAN;
	case TYPE_STRING:
		return BYTEORDER_HOST_ENDIAN;
	default:
		break;
	}

	return BYTEORDER_INVALID;
}

static void interval_expr_copy(struct expr *dst, struct expr *src)
{
	if (src->comment)
		dst->comment = xstrdup(src->comment);
	if (src->timeout)
		dst->timeout = src->timeout;
	if (src->expiration)
		dst->expiration = src->expiration;

	list_splice_init(&src->stmt_list, &dst->stmt_list);
}

static void set_elem_add(const struct set *set, struct expr *init, mpz_t value,
			 uint32_t flags, enum byteorder byteorder)
{
	struct expr *expr;

	expr = constant_expr_alloc(&internal_location, set->key->dtype,
				   byteorder, set->key->len, NULL);
	mpz_set(expr->value, value);
	expr = set_elem_expr_alloc(&internal_location, expr);
	expr->flags = flags;

	compound_expr_add(init, expr);
}

struct expr *get_set_intervals(const struct set *set, const struct expr *init)
{
	enum byteorder byteorder = get_key_byteorder(set->key);
	struct expr *new_init;
	mpz_t low, high;
	struct expr *i;

	mpz_init2(low, set->key->len);
	mpz_init2(high, set->key->len);

	new_init = list_expr_alloc(&internal_location);

	list_for_each_entry(i, &init->expressions, list) {
		switch (i->key->etype) {
		case EXPR_VALUE:
			set_elem_add(set, new_init, i->key->value,
				     i->flags, byteorder);
			break;
		case EXPR_CONCAT:
			compound_expr_add(new_init, expr_clone(i));
			i->flags |= EXPR_F_INTERVAL_END;
			compound_expr_add(new_init, expr_clone(i));
			break;
		case EXPR_SET_ELEM_CATCHALL:
			compound_expr_add(new_init, expr_clone(i));
			break;
		default:
			range_expr_value_low(low, i);
			set_elem_add(set, new_init, low, 0, i->byteorder);
			range_expr_value_high(high, i);
			mpz_add_ui(high, high, 1);
			set_elem_add(set, new_init, high,
				     EXPR_F_INTERVAL_END, i->byteorder);
			break;
		}
	}

	mpz_clear(low);
	mpz_clear(high);

	return new_init;
}

static struct expr *get_set_interval_find(const struct set *cache_set,
					  struct expr *left,
					  struct expr *right)
{
	const struct set *set = cache_set;
	struct expr *range = NULL;
	struct expr *i;
	mpz_t val;

	mpz_init2(val, set->key->len);

	list_for_each_entry(i, &set->init->expressions, list) {
		switch (i->key->etype) {
		case EXPR_VALUE:
			if (expr_basetype(i->key)->type != TYPE_STRING)
				break;
			/* string type, check if its a range (wildcard), so
			 * fall through.
			 */
		case EXPR_PREFIX:
		case EXPR_RANGE:
			range_expr_value_low(val, i);
			if (left && mpz_cmp(left->key->value, val))
				break;

			range_expr_value_high(val, i);
			if (right && mpz_cmp(right->key->value, val))
				break;

			range = expr_clone(i->key);
			goto out;
		default:
			break;
		}
	}
out:
	mpz_clear(val);

	return range;
}

static struct expr *expr_value(struct expr *expr)
{
	switch (expr->etype) {
	case EXPR_MAPPING:
		return expr->left->key;
	case EXPR_SET_ELEM:
		return expr->key;
	case EXPR_VALUE:
		return expr;
	default:
		BUG("invalid expression type %s\n", expr_name(expr));
	}
}

static struct expr *__expr_to_set_elem(struct expr *low, struct expr *expr)
{
	struct expr *elem = set_elem_expr_alloc(&low->location, expr);

	if (low->etype == EXPR_MAPPING) {
		interval_expr_copy(elem, low->left);

		elem = mapping_expr_alloc(&low->location, elem,
						    expr_clone(low->right));
	} else {
		interval_expr_copy(elem, low);
	}
	elem->flags |= EXPR_F_KERNEL;

	return elem;
}

static struct expr *expr_to_set_elem(struct expr *e)
{
	unsigned int len = div_round_up(e->len, BITS_PER_BYTE);
	unsigned int str_len;
	char data[len + 1];
	struct expr *expr;

	if (expr_basetype(expr_value(e))->type != TYPE_STRING)
		return expr_clone(e);

	mpz_export_data(data, expr_value(e)->value, BYTEORDER_BIG_ENDIAN, len);

	str_len = strnlen(data, len);
	if (str_len >= len || str_len == 0)
		return expr_clone(e);

	data[str_len] = '*';

	expr = constant_expr_alloc(&e->location, e->dtype,
				   BYTEORDER_HOST_ENDIAN,
				   (str_len + 1) * BITS_PER_BYTE, data);

	return __expr_to_set_elem(e, expr);
}

int get_set_decompose(struct set *cache_set, struct set *set)
{
	struct expr *i, *next, *range;
	struct expr *left = NULL;
	struct expr *new_init;

	new_init = set_expr_alloc(&internal_location, set);

	list_for_each_entry_safe(i, next, &set->init->expressions, list) {
		if (i->flags & EXPR_F_INTERVAL_END && left) {
			list_del(&left->list);
			list_del(&i->list);
			mpz_sub_ui(i->key->value, i->key->value, 1);
			range = get_set_interval_find(cache_set, left, i);
			if (!range) {
				expr_free(left);
				expr_free(i);
				expr_free(new_init);
				errno = ENOENT;
				return -1;
			}
			expr_free(left);
			expr_free(i);

			compound_expr_add(new_init, range);
			left = NULL;
		} else {
			if (left) {
				range = get_set_interval_find(cache_set,
							      left, NULL);
				if (range)
					compound_expr_add(new_init, range);
				else
					compound_expr_add(new_init,
							  expr_to_set_elem(left));
			}
			left = i;
		}
	}
	if (left) {
		range = get_set_interval_find(cache_set, left, NULL);
		if (range)
			compound_expr_add(new_init, range);
		else
			compound_expr_add(new_init, expr_to_set_elem(left));
	}

	expr_free(set->init);
	set->init = new_init;

	return 0;
}

static bool range_is_prefix(const mpz_t range)
{
	mpz_t tmp;
	bool ret;

	mpz_init_set(tmp, range);
	mpz_add_ui(tmp, tmp, 1);
	mpz_and(tmp, range, tmp);
	ret = !mpz_cmp_ui(tmp, 0);
	mpz_clear(tmp);
	return ret;
}

static int expr_value_cmp(const void *p1, const void *p2)
{
	struct expr *e1 = *(void * const *)p1;
	struct expr *e2 = *(void * const *)p2;
	int ret;

	if (expr_value(e1)->etype == EXPR_CONCAT)
		return -1;

	ret = mpz_cmp(expr_value(e1)->value, expr_value(e2)->value);
	if (ret == 0) {
		if (e1->flags & EXPR_F_INTERVAL_END)
			return -1;
		else if (e2->flags & EXPR_F_INTERVAL_END)
			return 1;
	}

	return ret;
}

/* Given start and end elements of a range, check if it can be represented as
 * a single netmask, and if so, how long, by returning zero or a positive value.
 */
static int range_mask_len(const mpz_t start, const mpz_t end, unsigned int len)
{
	mpz_t tmp_start, tmp_end;
	int ret;

	mpz_init_set(tmp_start, start);
	mpz_init_set(tmp_end, end);

	while (mpz_cmp(tmp_start, tmp_end) <= 0 &&
		!mpz_tstbit(tmp_start, 0) && mpz_tstbit(tmp_end, 0) &&
		len--) {
		mpz_fdiv_q_2exp(tmp_start, tmp_start, 1);
		mpz_fdiv_q_2exp(tmp_end, tmp_end, 1);
	}

	ret = !mpz_cmp(tmp_start, tmp_end) ? (int)len : -1;

	mpz_clear(tmp_start);
	mpz_clear(tmp_end);

	return ret;
}

/* Given a set with two elements (start and end), transform them into a
 * concatenation of ranges. That is, from a list of start expressions and a list
 * of end expressions, form a list of start - end expressions.
 */
void concat_range_aggregate(struct expr *set)
{
	struct expr *i, *start = NULL, *end, *r1, *r2, *next, *r1_next, *tmp;
	struct list_head *r2_next;
	int prefix_len, free_r1;
	mpz_t range, p;

	list_for_each_entry_safe(i, next, &set->expressions, list) {
		if (!start) {
			start = i;
			continue;
		}
		end = i;

		/* Walk over r1 (start expression) and r2 (end) in parallel,
		 * form ranges between corresponding r1 and r2 expressions,
		 * store them by replacing r2 expressions, and free r1
		 * expressions.
		 */
		r2 = list_first_entry(&expr_value(end)->expressions,
				      struct expr, list);
		list_for_each_entry_safe(r1, r1_next,
					 &expr_value(start)->expressions,
					 list) {
			bool string_type = false;

			mpz_init(range);
			mpz_init(p);

			r2_next = r2->list.next;
			free_r1 = 0;

			if (!mpz_cmp(r1->value, r2->value)) {
				free_r1 = 1;
				goto next;
			}

			if (expr_basetype(r1)->type == TYPE_STRING &&
			    expr_basetype(r2)->type == TYPE_STRING) {
				string_type = true;
				mpz_switch_byteorder(r1->value, r1->len / BITS_PER_BYTE);
				mpz_switch_byteorder(r2->value, r2->len / BITS_PER_BYTE);
			}

			mpz_sub(range, r2->value, r1->value);
			mpz_sub_ui(range, range, 1);
			mpz_and(p, r1->value, range);

			/* Check if we are forced, or if it's anyway preferable,
			 * to express the range as a wildcard string, or two points
			 * instead of a netmask.
			 */
			prefix_len = range_mask_len(r1->value, r2->value,
						    r1->len);
			if (string_type) {
				mpz_switch_byteorder(r1->value, r1->len / BITS_PER_BYTE);
				mpz_switch_byteorder(r2->value, r2->len / BITS_PER_BYTE);
			}

			if (prefix_len >= 0 &&
			    (prefix_len % BITS_PER_BYTE) == 0 &&
			    string_type) {
				unsigned int str_len = prefix_len / BITS_PER_BYTE;
				char data[str_len + 2];

				mpz_export_data(data, r1->value, BYTEORDER_HOST_ENDIAN, str_len);
				data[str_len] = '*';

				tmp = constant_expr_alloc(&r1->location, r1->dtype,
							  BYTEORDER_HOST_ENDIAN,
							  (str_len + 1) * BITS_PER_BYTE, data);
				tmp->len = r2->len;
				list_replace(&r2->list, &tmp->list);
				r2_next = tmp->list.next;
				expr_free(r2);
				free_r1 = 1;
				goto next;
			}

			if (prefix_len < 0 ||
			    !(r1->dtype->flags & DTYPE_F_PREFIX)) {
				tmp = range_expr_alloc(&r1->location, r1,
						       r2);

				list_replace(&r2->list, &tmp->list);
				r2_next = tmp->list.next;
			} else {
				tmp = prefix_expr_alloc(&r1->location, r1,
							prefix_len);
				tmp->len = r2->len;

				list_replace(&r2->list, &tmp->list);
				r2_next = tmp->list.next;
				expr_free(r2);
			}

next:
			mpz_clear(p);
			mpz_clear(range);

			r2 = list_entry(r2_next, typeof(*r2), list);
			compound_expr_remove(start, r1);

			if (free_r1)
				expr_free(r1);
		}

		compound_expr_remove(set, start);
		expr_free(start);
		start = NULL;
	}
}

static struct expr *interval_to_prefix(struct expr *low, struct expr *i, const mpz_t range)
{
	unsigned int prefix_len;
	struct expr *prefix;

	prefix_len = expr_value(i)->len - mpz_scan0(range, 0);
	prefix = prefix_expr_alloc(&low->location,
				   expr_clone(expr_value(low)),
						   prefix_len);
	prefix->len = expr_value(i)->len;

	return __expr_to_set_elem(low, prefix);
}

static struct expr *interval_to_string(struct expr *low, struct expr *i, const mpz_t range)
{
	unsigned int len = div_round_up(i->len, BITS_PER_BYTE);
	unsigned int prefix_len, str_len;
	char data[len + 2];
	struct expr *expr;

	prefix_len = expr_value(i)->len - mpz_scan0(range, 0);

	if (prefix_len > i->len || prefix_len % BITS_PER_BYTE)
		return interval_to_prefix(low, i, range);

	mpz_export_data(data, expr_value(low)->value, BYTEORDER_BIG_ENDIAN, len);

	str_len = strnlen(data, len);
	if (str_len >= len || str_len == 0)
		return interval_to_prefix(low, i, range);

	data[str_len] = '*';

	expr = constant_expr_alloc(&low->location, low->dtype,
				   BYTEORDER_HOST_ENDIAN,
				   (str_len + 1) * BITS_PER_BYTE, data);

	return __expr_to_set_elem(low, expr);
}

static struct expr *interval_to_range(struct expr *low, struct expr *i, mpz_t range)
{
	struct expr *tmp;

	tmp = constant_expr_alloc(&low->location, low->dtype,
				  low->byteorder, expr_value(low)->len,
				  NULL);

	mpz_add(range, range, expr_value(low)->value);
	mpz_set(tmp->value, range);

	tmp = range_expr_alloc(&low->location,
			       expr_clone(expr_value(low)),
			       tmp);

	return __expr_to_set_elem(low, tmp);
}

static void
add_interval(struct expr *set, struct expr *low, struct expr *i)
{
	struct expr *expr;
	mpz_t range, p;

	mpz_init(range);
	mpz_init(p);

	mpz_sub(range, expr_value(i)->value, expr_value(low)->value);
	if (i->etype != EXPR_VALUE)
		mpz_sub_ui(range, range, 1);

	mpz_and(p, expr_value(low)->value, range);

	if (!mpz_cmp_ui(range, 0)) {
		if (expr_basetype(low)->type == TYPE_STRING)
			mpz_switch_byteorder(expr_value(low)->value,
					     expr_value(low)->len / BITS_PER_BYTE);
		low->flags |= EXPR_F_KERNEL;
		expr = expr_get(low);
	} else if (range_is_prefix(range) && !mpz_cmp_ui(p, 0)) {

		if (i->dtype->flags & DTYPE_F_PREFIX)
			expr = interval_to_prefix(low, i, range);
		else if (expr_basetype(i)->type == TYPE_STRING)
			expr = interval_to_string(low, i, range);
		else
			expr = interval_to_range(low, i, range);
	} else
		expr = interval_to_range(low, i, range);

	compound_expr_add(set, expr);

	mpz_clear(range);
	mpz_clear(p);
}

void interval_map_decompose(struct expr *set)
{
	struct expr *i, *next, *low = NULL, *end, *catchall = NULL, *key;
	struct expr **elements, **ranges;
	unsigned int n, m, size;
	bool interval;

	if (set->size == 0)
		return;

	elements = xmalloc_array(set->size, sizeof(struct expr *));
	ranges = xmalloc_array(set->size * 2, sizeof(struct expr *));

	/* Sort elements */
	n = 0;
	list_for_each_entry_safe(i, next, &set->expressions, list) {
		key = NULL;
		if (i->etype == EXPR_SET_ELEM)
			key = i->key;
		else if (i->etype == EXPR_MAPPING)
			key = i->left->key;

		if (key && key->etype == EXPR_SET_ELEM_CATCHALL) {
			list_del(&i->list);
			catchall = i;
			continue;
		}
		compound_expr_remove(set, i);
		elements[n++] = i;
	}
	qsort(elements, n, sizeof(elements[0]), expr_value_cmp);
	size = n;

	/* Transform points (single values) into half-closed intervals */
	n = 0;
	interval = false;
	for (m = 0; m < size; m++) {
		i = elements[m];

		if (i->flags & EXPR_F_INTERVAL_END)
			interval = false;
		else if (interval) {
			end = expr_clone(i);
			end->flags |= EXPR_F_INTERVAL_END;
			ranges[n++] = end;
		} else
			interval = true;

		ranges[n++] = i;
	}
	size = n;

	for (n = 0; n < size; n++) {
		i = ranges[n];

		if (low == NULL) {
			if (i->flags & EXPR_F_INTERVAL_END) {
				/*
				 * End of interval mark
				 */
				expr_free(i);
				continue;
			} else {
				/*
				 * Start a new interval
				 */
				low = i;
				continue;
			}
		}

		add_interval(set, low, i);

		if (i->flags & EXPR_F_INTERVAL_END) {
			expr_free(low);
			low = NULL;
		}
		expr_free(i);
	}

	if (!low) /* no unclosed interval at end */
		goto out;

	i = constant_expr_alloc(&low->location, low->dtype,
				low->byteorder, expr_value(low)->len, NULL);
	mpz_bitmask(i->value, i->len);

	if (!mpz_cmp(i->value, expr_value(low)->value)) {
		compound_expr_add(set, low);
	} else {
		add_interval(set, low, i);
		expr_free(low);
	}

	expr_free(i);

out:
	if (catchall)
		compound_expr_add(set, catchall);

	xfree(ranges);
	xfree(elements);
}
