/*
 * 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 "tlv.h"
#include "tlv_private.h"
#include "net.h"
#include "utils.h"

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

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

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;
}

void tlv_destroy(struct tlv *t)
{
	size_t i = 0;
	size_t tlv_count;
	struct tlv *arr;
	switch (t->type)
	{
	case REGURAL:
	case HEARTBEAT:
	case DISCOVERY:
		tlv_count = t->length / sizeof(struct tlv);
		arr = t->data;
		for (i = 0; i < tlv_count; i++) {
			tlv_destroy(&arr[i]);
		}
	default:
		free(t->data);
		t->length = 0;
		break;
	}
}

size_t tlv_raw_size(const struct tlv *t)
{
	return sizeof(*t) + t->length;
}

int tlv_push_data(struct tlv *t, const char *data, size_t size)
{
	int ret = 0;
	size_t final_size = tlv_raw_size(t) + size;
	if (final_size > TLV_SZ_MAX_RAW) {
		ret = E_TLV_OVERFLOW;
	} else {
		t->data = realloc(t->data, final_size);
		memcpy(t->data + t->length, data, size);
		t->length = final_size;
	}
	return ret;
}

void tlv_init(struct tlv *t, enum tlv_type type)
{
	t->type = type;
	t->length = 0;
	t->data = NULL;
}

int tlv_push_tlv(struct tlv *t, const struct tlv *other)
{
	int ret = 0;
	size_t other_size;
	size_t final_size;

	other_size = tlv_raw_size(other);
	final_size = tlv_raw_size(t) + other_size;
	if (final_size > TLV_SZ_MAX_RAW) {
		ret = E_TLV_OVERFLOW;
	} else {
		tlv_get_raw(other, t->data + t->length);
		t->length = final_size;
	}

	return ret;
}