/** @file
 *
 * Structures that most TVB users should not be accessing directly.
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#ifndef __TVBUFF_INT_H__
#define __TVBUFF_INT_H__

struct tvbuff;

struct tvb_ops {
	size_t tvb_size;
	void (*tvb_free)(struct tvbuff *tvb);
	unsigned (*tvb_offset)(const struct tvbuff *tvb, unsigned counter);
	const uint8_t *(*tvb_get_ptr)(struct tvbuff *tvb, unsigned abs_offset, unsigned abs_length);
	void *(*tvb_memcpy)(struct tvbuff *tvb, void *target, unsigned offset, unsigned length);

	int (*tvb_find_uint8)(tvbuff_t *tvb, unsigned abs_offset, unsigned limit, uint8_t needle);
	int (*tvb_ws_mempbrk_pattern_uint8)(tvbuff_t *tvb, unsigned abs_offset, unsigned limit, const ws_mempbrk_pattern* pattern, unsigned char *found_needle);

	tvbuff_t *(*tvb_clone)(tvbuff_t *tvb, unsigned abs_offset, unsigned abs_length);
};

/*
 * Tvbuff flags.
 */
#define TVBUFF_FRAGMENT		0x00000001	/* this is a fragment */

struct tvbuff {
	/* Doubly linked list pointers */
	tvbuff_t                *next;

	/* Record-keeping */
	const struct tvb_ops   *ops;
	bool		initialized;
	unsigned			flags;
	struct tvbuff		*ds_tvb;  /**< data source top-level tvbuff */

	/** Pointer to the data for this tvbuff.
	 * It might be null, which either means that 1) it's a
	 * zero-length tvbuff or 2) the tvbuff was lazily
	 * constructed, so that we don't allocate a buffer of
	 * backing data and fill it in unless we need that
	 * data, e.g. when tvb_get_ptr() is called.
	 */
	const uint8_t		*real_data;

	/** Amount of data that's available from the capture
	 * file.  This is the length of virtual buffer (and/or
	 * real_data).  It may be less than the reported
	 * length if this is from a packet that was cut short
	 * by the capture process.
	 *
	 * This must never be > reported_length or contained_length. */
	unsigned			length;

	/** Amount of data that was reported as being in
	 * the packet or other data that this represents.
	 * As indicated above, it may be greater than the
	 * amount of data that's available. */
	unsigned			reported_length;

	/** If this was extracted from a parent tvbuff,
	 * this is the amount of extracted data that
	 * was reported as being in the parent tvbuff;
	 * if this represents a blob of data in that
	 * tvbuff that has a length specified by data
	 * in that tvbuff, it might be greater than
	 * the amount of data that was actually there
	 * to extract, so it could be greater than
	 * reported_length.
	 *
	 * If this wasn't extracted from a parent tvbuff,
	 * this is the same as reported_length.
	 *
	 * This must never be > reported_length. */
	unsigned			contained_length;

	/* Offset from beginning of first "real" tvbuff. */
	int			raw_offset;
};

tvbuff_t *tvb_new(const struct tvb_ops *ops);

tvbuff_t *tvb_new_proxy(tvbuff_t *backing);

void tvb_add_to_chain(tvbuff_t *parent, tvbuff_t *child);

unsigned tvb_offset_from_real_beginning_counter(const tvbuff_t *tvb, const unsigned counter);

void tvb_check_offset_length(const tvbuff_t *tvb, const int offset, int const length_val, unsigned *offset_ptr, unsigned *length_ptr);
#endif
