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/*
* Usurpataion --- server-client protocol private interface.
*
* 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
*/
#ifndef PROTOCOL_H_PRIVATE
#define PROTOCOL_H_PRIVATE
#include "utils.h"
#define E_PACKET_OVERFLOW (1 << 0)
/** Read as "A maximum of 16 tlv's per packet". */
#define TLV_BUF_SIZE (16)
/* Pease don't rape the buffer with long messages, daemon-kun. */
#define MSG_BUF_SIZE (257)
/* Maximum size of packet that can fit into the packet buffer. UDP can carry
* bigger packets but memory is hard to come by and more won't be needed
* anyway.
* */
#define PACKET_MAX_SIZE (512)
/** Returns the amount of tlv's int a packet.
*
* If a tlv reports length that goes beyond the end of a packet, errno is set
* to TLV_OVERFLOW. To check this, set errno to 0 first.
*
* @param packet data parsed from a packet. Function cannot use raw packets.
*
* @return Amount of tlv's in a packet.
* */
size_t tlv_count(const struct packet_data * const packet_data);
/**
* Parses tlv's from packet data and writes them to a buffer of given size.
*
* Returns how many tlv's were actually parsed.
*
* To check for errors, set errno to 0 and check after calling.
*
* Not yet implemented.
*
* @param data Data from network packet
* @param buf Buffer to store parsed tlv's
* @param buf_size Size of buffer used to store tlv's
*
* @return Number of tlv's actually parsed. Greter than or equal to buffer
* size, if an error occurs.
* */
size_t get_tlvs( const struct packet_data * const data,
const struct tlv *buf,
size_t buf_size);
/** Takes a null-terminated string and appends it to the next outgoing packet.
*
* @return Returns 0 on success. Otherwise: E_PACKET_OVERFLOW.
*
* */
int push_string(char *str);
/** Reinterprets char * as fpi1_t * and appends it to the outgoing packet as a
* tlv.
*/
int push_fpi1(char *num);
/** Reinterprets char * as time_t * and appends it to the outgoing packet as a
* tlv.
*/
int push_timestamp(char *data);
/**
* Pushes a request for daemon to repeat a message identified by a msg_index_t.
*
* @param data Pointer to a msg_index_t.
*
* @return 0 on success or E_PACKET_OVERFLOW, if not enough space is available
* to push all the data.
*/
int push_request(char *data);
/**
* Pushes a message to the outgoing packet buffer as a reply. A reply is just
* a null terminated string.
*
* @param data msg_idx_t representing sequence number since beggining of
* connection and a null-terminated string.
*
* @return On success --- 0 or E_PACKET_OVERFLOW, if not enough buffer is
* available.
*/
int push_reply(char *data);
/** Reinterprets char * as uuid_t * and appends it to the outgoing packet as a
* tlv.
*/
int push_uuid(char *data);
/* Appends tlv_type and size of data to a packet effectively creating a tlv
* header.
*/
int push_tlv_header(enum tlv_type type, size_t size);
#endif /* PROTOCOL_H_PRIVATE */
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