/*
 * Usurpation – clinet-server protocol implementation.
 *
 * Copyright (C) 2019 Ramūnas Mažeikis
 * Copyright (C) 2019 Gediminas Jakutis
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; version 2.1
 * of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

/**
 * Common parts of protocol implementation. Handling of anything that actually
 * deals with connection descriptor has to be implemented by device and daemon
 * separately.
 */

#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "tlv.h"
#include "utils.h"

#ifdef unix
#include <arpa/inet.h>
#else
#include <lwip/def.h>
#endif

int tlv_get(char *in, struct tlv *tlv, char **saveptr)
{
	struct tlv_header head;
	int ret = A_OK;

	memcpy(&head, in, sizeof(head));
	head = ntoh_tlvh(&head);

	if (head.type == INVALID || !head.size) {
		ret = NONEWDATA;
		goto out;
	}

	tlv->head = head;
	tlv->data = in + sizeof(head);
	if (saveptr) {
		*saveptr = in + sizeof(head) + head.size;
	}
out:
	return ret;
}

struct tlv_header ntoh_tlvh(const struct tlv_header * const in)
{
	struct tlv_header ret;

	ret.type = ntohl(in->type);
	ret.size = ntohl(in->size);

	return ret;
}

struct tlv_header hton_tlvh(const struct tlv_header * const in)
{
	struct tlv_header ret;

	ret.type = htonl(in->type);
	ret.size = htonl(in->size);

	return ret;
}

int tlv_pack(struct tlv_packet *pack, struct tlv *tlv)
{
	struct tlv_header head;
	size_t raw_size;
	int ret = A_OK;

	/* packed tlv loses the pointer, so only take the header part into account */
	raw_size = sizeof(tlv->head) + tlv->head.size;

	if ((raw_size + pack->cursor + sizeof(tlv->head)) >= TLV_SZ_MAX) {
		ret = ERROR;
	} else {
		if (pack->size < pack->cursor + raw_size) {
			pack->data = realloc(pack->data, pack->size + raw_size);
			pack->size += raw_size;
		}

		head = tlv->head;
		head = hton_tlvh(&head);
		memcpy(pack->data + pack->cursor, &head, sizeof(head));
		pack->cursor += sizeof(tlv->head);
		if (tlv->head.size && tlv->data) {
			memcpy(pack->data + pack->cursor, tlv->data, tlv->head.size);
			pack->cursor += tlv->head.size;
		}
	}
	return ret;
}

int tlv_packet_finalize(struct tlv_packet *pack)
{
	struct tlv terminator;
	int ret = A_OK;

	terminator = tlv_none;

	tlv_pack(pack, &terminator);

	return ret;
}

struct tlv *tlv_init(struct tlv *in, enum tlv_type type)
{
	in->head.type = type;
	in->head.size = 0;
	in->data = NULL;

	return in;
}

void tlv_destroy(struct tlv *in)
{
	free(in->data);
	*in = tlv_none;
}

struct tlv_packet *tlv_packet_init(struct tlv_packet *in)
{
	in->size = 0;
	in->cursor = 0;
	in->data = NULL;

	return in;
}

struct tlv_packet *tlv_packet_reset(struct tlv_packet *in)
{
	memset(in->data, 0, in->cursor);
	in->cursor = 0;

	return in;
}

void tlv_packet_destroy(struct tlv_packet *in)
{
	free(in->data);
	in->size = 0;
	in->cursor = 0;
	in->data = NULL;
}