/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright (C)2012 Xiph.Org Foundation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file opus_common.c Common functions of the opus decoder and audio format
 * handler.
 */

#include "para.h"
#include "error.h"
#include "opus_common.h"
#include "portable_io.h"

struct packet {
	const char *data;
	int maxlen;
	int pos;
};

static int read_chars(struct packet *p, unsigned char *str, int nb_chars)
{
	int i;

	if (p->pos > p->maxlen - nb_chars)
		return 0;
	for (i = 0; i < nb_chars; i++)
		str[i] = p->data[p->pos++];
	return 1;
}

static int read_uint32(struct packet *p, uint32_t *val)
{
	if (p->pos > p->maxlen - 4)
		return 0;
	*val = read_u32(p->data + p->pos);
	p->pos += 4;
	return 1;
}

static int read_uint16(struct packet *p, uint16_t *val)
{
	if (p->pos > p->maxlen - 2)
		return 0;
	*val = read_u16(p->data + p->pos);
	p->pos += 2;
	return 1;
}

/**
 * Get metadata of an opus stream.
 *
 * This is called from both the audio format handler (which passes ogg packet
 * 0) and from the decoder.
 *
 * \param packet Start of the packet.
 * \param len Number of bytes.
 * \param h Result.
 *
 * \return Standard.
 */
int opus_parse_header(const char *packet, int len, struct opus_header *h)
{
	int i;
	char str[9];
	struct packet p;
	unsigned char ch, channel_mapping;

	p.data = packet;
	p.maxlen = len;
	p.pos = 0;
	str[8] = 0;
	if (len < 19)
		return -E_OPUS_HEADER;
	read_chars(&p, (unsigned char*)str, 8);
	if (memcmp(str, "OpusHead", 8) != 0)
		return -E_OPUS_HEADER;

	if (!read_chars(&p, &ch, 1))
		return -E_OPUS_HEADER;
	h->version = ch;
	if ((h->version & 240) != 0) /* Only major version 0 supported. */
		return -E_OPUS_HEADER;

	if (!read_chars(&p, &ch, 1))
		return -E_OPUS_HEADER;
	h->channels = ch;
	if (h->channels == 0)
		return -E_OPUS_HEADER;

	if (!read_uint16(&p, &h->preskip))
		return -E_OPUS_HEADER;

	if (!read_uint32(&p, &h->input_sample_rate))
		return -E_OPUS_HEADER;

	if (!read_uint16(&p, &h->gain))
		return -E_OPUS_HEADER;

	if (!read_chars(&p, &ch, 1))
		return -E_OPUS_HEADER;
	channel_mapping = ch;

	if (channel_mapping != 0) {
		if (!read_chars(&p, &ch, 1))
			return -E_OPUS_HEADER;

		if (ch < 1)
			return -E_OPUS_HEADER;
		h->nb_streams = ch;

		if (!read_chars(&p, &ch, 1))
			return -E_OPUS_HEADER;

		if (ch > h->nb_streams || (ch + h->nb_streams) > 255)
			return -E_OPUS_HEADER;
		h->nb_coupled = ch;

		/* Multi-stream support */
		for (i = 0; i < h->channels; i++) {
			if (!read_chars(&p, &h->stream_map[i], 1))
				return -E_OPUS_HEADER;
			if (h->stream_map[i] > (h->nb_streams + h->nb_coupled)
					&& h->stream_map[i] != 255)
				return -E_OPUS_HEADER;
		}
	} else {
		if (h->channels > 2)
			return -E_OPUS_HEADER;
		h->nb_streams = 1;
		h->nb_coupled = h->channels > 1;
		h->stream_map[0] = 0;
		h->stream_map[1] = 1;
	}
	/*
	 * For version 0/1 we know there won't be any more data so reject any
	 * that have data past the end.
	 */
	if ((h->version == 0 || h->version == 1) && p.pos != len)
		return -E_OPUS_HEADER;
	return 1;
}