/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright Red Hat
 * Author: David Gibson <david@gibson.dropbear.id.au>
 *
 * Definitions for the global table of packet flows.
 */
#ifndef FLOW_TABLE_H
#define FLOW_TABLE_H

#include "tcp_conn.h"
#include "icmp_flow.h"

/**
 * struct flow_free_cluster - Information about a cluster of free entries
 * @f:		Generic flow information
 * @n:		Number of entries in the free cluster (including this one)
 * @next:	Index of next free cluster
 */
struct flow_free_cluster {
	/* Must be first element */
	struct flow_common f;
	unsigned n;
	unsigned next;
};

/**
 * union flow - Descriptor for a logical packet flow (e.g. connection)
 * @f:		Fields common between all variants
 * @tcp:	Fields for non-spliced TCP connections
 * @tcp_splice:	Fields for spliced TCP connections
*/
union flow {
	struct flow_common f;
	struct flow_free_cluster free;
	struct tcp_tap_conn tcp;
	struct tcp_splice_conn tcp_splice;
	struct icmp_ping_flow ping;
};

/* Global Flow Table */
extern unsigned flow_first_free;
extern union flow flowtab[];


/** flow_idx - Index of flow from common structure
 * @f:	Common flow fields pointer
 *
 * Return: index of @f in the flow table
 */
static inline unsigned flow_idx(const struct flow_common *f)
{
	return (union flow *)f - flowtab;
}

/** FLOW_IDX - Find the index of a flow
 * @f_:	Flow pointer, either union flow * or protocol specific
 *
 * Return: index of @f in the flow table
 */
#define FLOW_IDX(f_)		(flow_idx(&(f_)->f))

/** FLOW - Flow entry at a given index
 * @idx:	Flow index
 *
 * Return: pointer to entry @idx in the flow table
 */
#define FLOW(idx)		(&flowtab[(idx)])

/** flow_at_sidx - Flow entry for a given sidx
 * @sidx:	Flow & side index
 *
 * Return: pointer to the corresponding flow entry, or NULL
 */
static inline union flow *flow_at_sidx(flow_sidx_t sidx)
{
	if (sidx.flow >= FLOW_MAX)
		return NULL;
	return FLOW(sidx.flow);
}

/** flow_sidx_t - Index of one side of a flow from common structure
 * @f:		Common flow fields pointer
 * @side:	Which side to refer to (0 or 1)
 *
 * Return: index of @f and @side in the flow table
 */
static inline flow_sidx_t flow_sidx(const struct flow_common *f,
				    int side)
{
	/* cppcheck-suppress [knownConditionTrueFalse, unmatchedSuppression] */
	ASSERT(side == !!side);

	return (flow_sidx_t){
		.side = side,
		.flow = flow_idx(f),
	};
}

/** FLOW_SIDX - Find the index of one side of a flow
 * @f_:		Flow pointer, either union flow * or protocol specific
 * @side:	Which side to index (0 or 1)
 *
 * Return: index of @f and @side in the flow table
 */
#define FLOW_SIDX(f_, side)	(flow_sidx(&(f_)->f, (side)))

union flow *flow_alloc(void);
void flow_alloc_cancel(union flow *flow);

#endif /* FLOW_TABLE_H */