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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 "protocol.h"
#include "protocol_private.h"
#include "net.h"
#include <stdlib.h>
#include <string.h>
#include <time.h>
#define READ_AS(from, type) (*(type*)(from))
#define GET_MSG_CHAR(i) (msg_buf[(i) % MSG_BUF_SIZE])
#define SET_MSG_CHAR(i, ch) msg_buf[(i) % MSG_BUF_SIZE] = (ch)
/* Increment message cursor */
#define IMC(x) ((msg_cursor + (x)) % MSG_BUF_SIZE)
/* Begins at 2 because this way we'll have two null's at the beggining
* indicating that going back is not possible.
* */
static int msg_cursor = 2;
/**
* Message buffer.
*
* Two consecutive null's indicate that going back is not possible.
* */
static char msg_buf[MSG_BUF_SIZE] = {0};
static int tlv_cursor = 0;
static struct tlv tlv_buf[TLV_BUF_SIZE] = {0};
static size_t packet_cursor = 0;
/* Outgoing packet.
* */
static char packet_buf[PACKET_MAX_SIZE] = {0};
static int push_bytes(cd_t connection, const void * const data, const size_t size)
{
if (packet_cursor + size >= PACKET_MAX_SIZE) {
return E_PACKET_OVERFLOW;
}
memcpy(packet_buf + packet_cursor, data, size);
packet_cursor += size;
return 0;
}
void clear_data(cd_t connection)
{
packet_cursor = 0;
}
int push_data(cd_t connection, const char *data, enum tlv_type type)
{
int ret = E_UNKNOWN_TYPE;
switch (type) {
case TEXT:
ret = push_string(connection, data);
break;
case FPI1:
ret = push_fpi1(connection, data);
break;
case TIMESTAMP:
ret = push_timestamp(connection, data);
break;
case REQUEST:
ret = push_request(connection, data);
break;
case REPLY:
ret = push_reply(connection, data);
break;
case UUID:
ret = push_uuid(connection, data);
break;
}
return ret;
}
static int push_string(cd_t connection, char *str)
{
int ret = 0;
size_t size = strlen(str);
ret |= push_tlv_header(connection, TEXT, size);
ret |= push_bytes(connection, str, size);
return ret;
}
static int push_fpi1(cd_t connection, char *num)
{
return push_tlv_header(connection, FPI1, sizeof(fpi1_t))
| push_bytes(connection, num, sizeof(fpi1_t));
}
static int push_timestamp(cd_t connection, char *data)
{
return push_tlv_header(connection, TIMESTAMP, sizeof(time_t))
| push_bytes(connection, data, sizeof(time_t));
}
static int push_request(cd_t connection, char *data)
{
return push_tlv_header(connection, REQUEST, sizeof(msg_idx_t))
| push_bytes(connection, data, sizeof(msg_idx_t));
}
static int push_reply(cd_t connection, char *data)
{
int ret = 0;
size_t msglen = strlen(data + sizeof(msg_idx_t));
ret |= push_tlv_header(connection, REPLY, msglen + sizeof(msg_idx_t));
ret |= push_bytes(connection, data, msglen);
return ret;
}
static int push_uuid(cd_t connection, char *data)
{
return push_tlv_header(connection, UUID, sizeof(uuid_t))
| push_bytes(connection, data, sizeof(uuid_t));
}
size_t tlv_count(const struct packet_data * const packet)
{
size_t cursor = 0;
size_t length = 0;
size_t ret = 0;
while (cursor < packet->packet_size) {
cursor += sizeof(enum tlv_type);
length = READ_AS(packet->data + cursor, enum tlv_type);
cursor += sizeof(size_t) + length;
ret++;
}
if (cursor != packet->packet_size) {
errno = E_TLV_OVERFLOW;
}
return ret;
}
size_t get_tlvs( const struct packet_data * const data,
const struct tlv *buf,
size_t buf_size)
{
size_t tlvs_read = 0;
size_t cursor = 0;
while (cursor < data->packet_size && tlvs_read <= buf_size) {
cursor += parse_tlv(data->data, cursor, buf + tlvs_read);
tlvs_read++;
}
if (cursor > data->packet_size) {
errno = E_TLV_OVERFLOW;
}
return tlvs_read;
}
size_t parse_tlv(char *data, size_t cursor, struct tlv *t)
{
char *begin = data + cursor;
t->type = READ_TLV_TYPE(data + cursor);
cursor += sizeof(enum tlv_type);
t->length += READ_SIZE_T(data + cursor);
data += sizeof(size_t);
t->data = data + cursor;
return data + cursor - begin + 1UL;
}
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