/*
 * Usurpataion --- clinet-server protocol implementation.
 *
 * Copyright (C) 2019 Ramūnas Mažeikis
 *
 * 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 "protocol.h"
#include "protocol_private.h"
#include "net.h"
#include "utils.h"

#define READ_AS(type, from)	(*((type*)(from)))

int push_tlv(struct tlv_packet *packet, enum tlv_type type, char *data)
{
	int ret = 0;
	size_t size;

	switch (type) {
	case TEXT:
		size = strlen(data);
		break;
	case FPI1:
		size = sizeof(fpi1_t);
		break;
	case TIMESTAMP:
		size = sizeof(time_t);
		break;
	case REQUEST:
		size = sizeof(msg_idx_t);
		break;
	case REPLY:
		size = sizeof(msg_idx_t) + strlen(data + sizeof(msg_idx_t));
		break;
	case UUID:
		size = sizeof(uuid_t);
		break;
	default:
		ret = E_UNKNOWN_TYPE;
	}
	ret |= push_tlv_header(packet, type, size);
	ret |= push_bytes(packet, data, size);
	return ret;
}

void clear_data(struct tlv_packet *packet)
{
	packet->offset = 0;
	packet->type = 0;
	memset(packet->data, 0, packet->size);
}

static int push_bytes(struct tlv_packet *packet, char *data, size_t size)
{
	int ret = 0;

	if (packet->offset + size >= packet->size) {
		ret = E_TLV_OVERFLOW;
	} else {
		memcpy(packet->data + packet->offset, data, size);
		packet->offset += size;
	}
}

static int push_tlv_header(struct tlv_packet *packet, enum tlv_type type, size_t size)
{
	int ret = 0;

	if (packet->offset + sizeof(type) + sizeof(size) >= packet->size) {
		ret = E_TLV_OVERFLOW;
	} else {
		memcpy(packet->data + packet->size, type, sizeof(type));
		packet->offset += sizeof(type);
		memcpy(packet->data + packet->offset, size, sizeof(size));
		packet->offset += sizeof(size);
	}
	return ret;
}

int get_tlv(struct tlv_parser *parser, struct tlv *ret)
{
	int ret = 0;

	if (parser->offset + sizeof(ret->type) + sizeof(ret->length) >= parser->size) {
		ret = E_TLV_OVERFLOW;
	} else {
		ret->type = memcpy(&ret->type, parser->data + parser->offset, sizeof(ret->type));
		parser->size += sizeof(ret->type);
		ret->length = memcpy(&ret->length, parser->data + parser->offset, sizeof(ret->length));
		parser->offset += sizeof(ret->length);
		if (parser->offset + ret->length >= parser->size) {
			ret = E_TLV_OVERFLOW;
		} else {
			memcpy(ret->data, parser->data, ret->length);
		}
	}
	return ret;
}

size_t tlv_data_size(struct tlv_parser *parser)
{
	size_t size;

	if (parser->offset + sizeof(enum tlv_type) + sizeof(size_t) >= parser->size) {
		size = 0;
	} else {
		memcpy(&size, parser->data + parser->offset + sizeof(enum tlv_type), sizeof(size_t));
	}
	return size;
}