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/*
* 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 <arpa/inet.h>
#include "tlv.h"
#include "net.h"
#include "utils.h"
struct tlv_header {
enum tlv_type type;
uint16_t size;
};
/**
* Returns tlv_size from packet
*/
uint16_t tlv_size(char *buf);
/**
* Returns tlv_type from packet.
*/
enum tlv_type tlv_get_type(char *buf);
/* Changes to be made:
* * Trust tlv size from raw data
* * Don't fail on 0 length. In that case data points to NULL
* * tlv_parser should be opaque.
* * Make a constructor that takes a user-supplied buffer.
*/
int tlv_get(struct tlv_parser *parser, struct tlv *ret)
{
int retval = 0;
size_t packet_size;
size_t final_size;
struct tlv *crr_tlv = parser->data + parser->offset;
packet_size = tlv_size(parser->data);
final_size = parser->offset + crr_tlv->length + sizeof(struct tlv_header);
if (final_size >= packet_size) {
return retval = E_TLV_OVERFLOW;
} else {
if (crr_tlv->length != 0) {
ret->data = parser->data + parser->offset + sizeof(struct tlv_header);
} else {
ret->data = NULL;
}
ret->type = crr_tlv->type;
ret->length = crr_tlv->length;
parser->offset += sizeof(struct tlv_header) + ret->length;
if (final_size == packet_size) {
retval = END_OF_PACKET;
}
}
return retval;
}
int tlv_parser_init(struct tlv_parser *parser, char *buf, struct tlv *ret)
{
/* Data points to the beggining of the buffer for size and
* type acquisition purposes.
* */
struct tlv_header *data = buf;
/* It is known that the first tlv will be of the meta kind.
* We can safely skip the header.
* */
parser->data = buf + sizeof(struct tlv_header);
ret->type = data->type;
ret->length = data->size;
}
uint16_t tlv_size(char *buf)
{
struct tlv_header *data = buf;
return htons(data->size);
}
enum tlv_type tlv_get_type(char *buf)
{
struct tlv_header *data = buf;
return READ_ENUM(data->type);
}
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;
}
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