dns_sd.h

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/**
 * @file dns_sd.h
 * @brief DNS-SD (DNS-Based Service Discovery)
 *
 * @section License
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * Copyright (C) 2010-2022 Oryx Embedded SARL. All rights reserved.
 *
 * This file is part of CycloneTCP Open.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * @author Oryx Embedded SARL (www.oryx-embedded.com)
 * @version 2.2.0
 **/
 
#ifndef _DNS_SD_H
#define _DNS_SD_H
 
//Dependencies
#include "core/net.h"
#include "dns/dns_common.h"
#include "mdns/mdns_common.h"
 
//DNS-SD support
#ifndef DNS_SD_SUPPORT
   #define DNS_SD_SUPPORT DISABLED
#elif (DNS_SD_SUPPORT != ENABLED && DNS_SD_SUPPORT != DISABLED)
   #error DNS_SD_SUPPORT parameter is not valid
#endif
 
//DNS-SD tick interval
#ifndef DNS_SD_TICK_INTERVAL
   #define DNS_SD_TICK_INTERVAL 250
#elif (DNS_SD_TICK_INTERVAL < 10)
   #error DNS_SD_TICK_INTERVAL parameter is not valid
#endif
 
//Maximum number of registered services
#ifndef DNS_SD_SERVICE_LIST_SIZE
   #define DNS_SD_SERVICE_LIST_SIZE 2
#elif (DNS_SD_SERVICE_LIST_SIZE < 1)
   #error DNS_SD_SERVICE_LIST_SIZE parameter is not valid
#endif
 
//Maximum length of service name
#ifndef DNS_SD_MAX_SERVICE_NAME_LEN
   #define DNS_SD_MAX_SERVICE_NAME_LEN 16
#elif (DNS_SD_MAX_SERVICE_NAME_LEN < 1)
   #error DNS_SD_MAX_SERVICE_NAME_LEN parameter is not valid
#endif
 
//Maximum length of instance name
#ifndef DNS_SD_MAX_INSTANCE_NAME_LEN
   #define DNS_SD_MAX_INSTANCE_NAME_LEN 32
#elif (DNS_SD_MAX_INSTANCE_NAME_LEN < 1)
   #error DNS_SD_MAX_INSTANCE_NAME_LEN parameter is not valid
#endif
 
//Maximum length of the discovery-time metadata (TXT record)
#ifndef DNS_SD_MAX_METADATA_LEN
   #define DNS_SD_MAX_METADATA_LEN 128
#elif (DNS_SD_MAX_METADATA_LEN < 1)
   #error DNS_SD_MAX_METADATA_LEN parameter is not valid
#endif
 
//Default resource record TTL (cache lifetime)
#ifndef DNS_SD_DEFAULT_RR_TTL
   #define DNS_SD_DEFAULT_RR_TTL 120
#elif (DNS_SD_DEFAULT_RR_TTL < 1)
   #error DNS_SD_DEFAULT_RR_TTL parameter is not valid
#endif
 
//Forward declaration of DnsSdContext structure
struct _DnsSdContext;
#define DnsSdContext struct _DnsSdContext
 
//C++ guard
#ifdef __cplusplus
extern "C" {
#endif
 
 
/**
 * @brief FSM state change callback
 **/
 
typedef void (*DnsSdStateChangeCallback)(DnsSdContext *context,
   NetInterface *interface, MdnsState state);
 
 
/**
 * @brief DNS-SD settings
 **/
 
typedef struct
{
   NetInterface *interface;                   ///<Underlying network interface
   uint_t numAnnouncements;                   ///<Number of announcement packets
   uint32_t ttl;                              ///<TTL resource record
   DnsSdStateChangeCallback stateChangeEvent; ///<FSM state change event
} DnsSdSettings;
 
 
/**
 * @brief DNS-SD service descriptor
 **/
 
typedef struct
{
   char_t name[DNS_SD_MAX_SERVICE_NAME_LEN + 1]; ///<Service name
   uint16_t priority;                            ///<Priority of the target host
   uint16_t weight;                              ///<Server selection mechanism
   uint16_t port;                                ///<Port on the target host of this service
   uint8_t metadata[DNS_SD_MAX_METADATA_LEN];    ///<Discovery-time metadata (TXT record)
   size_t metadataLength;                        ///<Length of the metadata
} DnsSdService;
 
 
/**
 * @brief DNS-SD context
 **/
 
struct _DnsSdContext
{
   DnsSdSettings settings;                                ///<DNS-SD settings
   bool_t running;                                        ///<DNS-SD is currently running
   MdnsState state;                                       ///<FSM state
   bool_t conflict;                                       ///<Conflict detected
   bool_t tieBreakLost;                                   ///<Tie-break lost
   systime_t timestamp;                                   ///<Timestamp to manage retransmissions
   systime_t timeout;                                     ///<Timeout value
   uint_t retransmitCount;                                ///<Retransmission counter
   char_t instanceName[DNS_SD_MAX_INSTANCE_NAME_LEN + 1]; ///<Service instance name
   DnsSdService serviceList[DNS_SD_SERVICE_LIST_SIZE];    ///<List of registered services
};
 
 
//Tick counter to handle periodic operations
extern systime_t dnsSdTickCounter;
 
//DNS-SD related functions
void dnsSdGetDefaultSettings(DnsSdSettings *settings);
error_t dnsSdInit(DnsSdContext *context, const DnsSdSettings *settings);
error_t dnsSdStart(DnsSdContext *context);
error_t dnsSdStop(DnsSdContext *context);
MdnsState dnsSdGetState(DnsSdContext *context);
 
error_t dnsSdSetInstanceName(DnsSdContext *context, const char_t *instanceName);
 
error_t dnsSdRegisterService(DnsSdContext *context, const char_t *serviceName,
   uint16_t priority, uint16_t weight, uint16_t port, const char_t *metadata);
 
error_t dnsSdUnregisterService(DnsSdContext *context, const char_t *serviceName);
 
uint_t dnsSdGetNumServices(DnsSdContext *context);
error_t dnsSdStartProbing(DnsSdContext *context);
 
void dnsSdTick(DnsSdContext *interface);
void dnsSdLinkChangeEvent(DnsSdContext *interface);
 
//C++ guard
#ifdef __cplusplus
}
#endif
 
#endif