text: /*************************************************************************/
  /*  ip.cpp                                                               */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
  /*                                                                       */
  /* Permission is hereby granted, free of charge, to any person obtaining */
  /* a copy of this software and associated documentation files (the       */
  /* "Software"), to deal in the Software without restriction, including   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* The above copyright notice and this permission notice shall be        */
  /* included in all copies or substantial portions of the Software.       */
  /*                                                                       */
  /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
  /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
  /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #include "ip.h"
  #include "hash_map.h"
  #include "os/semaphore.h"
  #include "os/thread.h"
  
  VARIANT_ENUM_CAST(IP::ResolverStatus);
  
  /************* RESOLVER ******************/
  
  struct _IP_ResolverPrivate {
  
  	struct QueueItem {
  
  		volatile IP::ResolverStatus status;
  		IP_Address response;
  		String hostname;
  		IP::Type type;
  
  		void clear() {
  			status = IP::RESOLVER_STATUS_NONE;
  			response = IP_Address();
  			type = IP::TYPE_NONE;
  			hostname = "";
  		};
  
  		QueueItem() {
  			clear();
  		};
  	};
  
  	QueueItem queue[IP::RESOLVER_MAX_QUERIES];
  
  	IP::ResolverID find_empty_id() const {
  
  		for (int i = 0; i < IP::RESOLVER_MAX_QUERIES; i++) {
  			if (queue[i].status == IP::RESOLVER_STATUS_NONE)
  				return i;
  		}
  		return IP::RESOLVER_INVALID_ID;
  	}
  
  	Mutex *mutex;
  	Semaphore *sem;
  
  	Thread *thread;
  	//Semaphore* semaphore;
  	bool thread_abort;
  
  	void resolve_queues() {
  
  		for (int i = 0; i < IP::RESOLVER_MAX_QUERIES; i++) {
  
  			if (queue[i].status != IP::RESOLVER_STATUS_WAITING)
  				continue;
  			queue[i].response = IP::get_singleton()->resolve_hostname(queue[i].hostname, queue[i].type);
  
  			if (!queue[i].response.is_valid())
  				queue[i].status = IP::RESOLVER_STATUS_ERROR;
  			else
  				queue[i].status = IP::RESOLVER_STATUS_DONE;
  		}
  	}
  
  	static void _thread_function(void *self) {
  
  		_IP_ResolverPrivate *ipr = (_IP_ResolverPrivate *)self;
  
  		while (!ipr->thread_abort) {
  
  			ipr->sem->wait();
  
  			ipr->mutex->lock();
  			ipr->resolve_queues();
  			ipr->mutex->unlock();
  		}
  	}
  
  	HashMap<String, IP_Address> cache;
  
  	static String get_cache_key(String p_hostname, IP::Type p_type) {
  		return itos(p_type) + p_hostname;
  	}
  };
  
  IP_Address IP::resolve_hostname(const String &p_hostname, IP::Type p_type) {
  
  	resolver->mutex->lock();
  
  	String key = _IP_ResolverPrivate::get_cache_key(p_hostname, p_type);
  	if (resolver->cache.has(key) && resolver->cache[key].is_valid()) {
  		IP_Address res = resolver->cache[key];
  		resolver->mutex->unlock();
  		return res;
  	}
  
  	IP_Address res = _resolve_hostname(p_hostname, p_type);
  	resolver->cache[key] = res;
  	resolver->mutex->unlock();
  	return res;
  }
  
  IP::ResolverID IP::resolve_hostname_queue_item(const String &p_hostname, IP::Type p_type) {
  
  	resolver->mutex->lock();
  
  	ResolverID id = resolver->find_empty_id();
  
  	if (id == RESOLVER_INVALID_ID) {
  		WARN_PRINT("Out of resolver queries");
  		resolver->mutex->unlock();
  		return id;
  	}
  
  	String key = _IP_ResolverPrivate::get_cache_key(p_hostname, p_type);
  	resolver->queue[id].hostname = p_hostname;
  	resolver->queue[id].type = p_type;
  	if (resolver->cache.has(key) && resolver->cache[key].is_valid()) {
  		resolver->queue[id].response = resolver->cache[key];
  		resolver->queue[id].status = IP::RESOLVER_STATUS_DONE;
  	} else {
  		resolver->queue[id].response = IP_Address();
  		resolver->queue[id].status = IP::RESOLVER_STATUS_WAITING;
  		if (resolver->thread)
  			resolver->sem->post();
  		else
  			resolver->resolve_queues();
  	}
  
  	resolver->mutex->unlock();
  	return id;
  }
  
  IP::ResolverStatus IP::get_resolve_item_status(ResolverID p_id) const {
  
  	ERR_FAIL_INDEX_V(p_id, IP::RESOLVER_MAX_QUERIES, IP::RESOLVER_STATUS_NONE);
  
  	resolver->mutex->lock();
  	if (resolver->queue[p_id].status == IP::RESOLVER_STATUS_NONE) {
  		ERR_PRINT("Condition status == IP::RESOLVER_STATUS_NONE");
  		resolver->mutex->unlock();
  		return IP::RESOLVER_STATUS_NONE;
  	}
  	IP::ResolverStatus res = resolver->queue[p_id].status;
  
  	resolver->mutex->unlock();
  	return res;
  }
  
  IP_Address IP::get_resolve_item_address(ResolverID p_id) const {
  
  	ERR_FAIL_INDEX_V(p_id, IP::RESOLVER_MAX_QUERIES, IP_Address());
  
  	resolver->mutex->lock();
  
  	if (resolver->queue[p_id].status != IP::RESOLVER_STATUS_DONE) {
  		ERR_PRINTS("Resolve of '" + resolver->queue[p_id].hostname + "'' didn't complete yet.");
  		resolver->mutex->unlock();
  		return IP_Address();
  	}
  
  	IP_Address res = resolver->queue[p_id].response;
  
  	resolver->mutex->unlock();
  	return res;
  }
  
  void IP::erase_resolve_item(ResolverID p_id) {
  
  	ERR_FAIL_INDEX(p_id, IP::RESOLVER_MAX_QUERIES);
  
  	resolver->mutex->lock();
  
  	resolver->queue[p_id].status = IP::RESOLVER_STATUS_NONE;
  
  	resolver->mutex->unlock();
  }
  
  void IP::clear_cache(const String &p_hostname) {
  
  	resolver->mutex->lock();
  
  	if (p_hostname.empty()) {
  		resolver->cache.clear();
  	} else {
  		resolver->cache.erase(_IP_ResolverPrivate::get_cache_key(p_hostname, IP::TYPE_NONE));
  		resolver->cache.erase(_IP_ResolverPrivate::get_cache_key(p_hostname, IP::TYPE_IPV4));
  		resolver->cache.erase(_IP_ResolverPrivate::get_cache_key(p_hostname, IP::TYPE_IPV6));
  		resolver->cache.erase(_IP_ResolverPrivate::get_cache_key(p_hostname, IP::TYPE_ANY));
  	}
  
  	resolver->mutex->unlock();
  }
  
  Array IP::_get_local_addresses() const {
  
  	Array addresses;
  	List<IP_Address> ip_addresses;
  	get_local_addresses(&ip_addresses);
  	for (List<IP_Address>::Element *E = ip_addresses.front(); E; E = E->next()) {
  		addresses.push_back(E->get());
  	}
  
  	return addresses;
  }
  
  void IP::_bind_methods() {
  
  	ClassDB::bind_method(D_METHOD("resolve_hostname", "host", "ip_type"), &IP::resolve_hostname, DEFVAL(IP::TYPE_ANY));
  	ClassDB::bind_method(D_METHOD("resolve_hostname_queue_item", "host", "ip_type"), &IP::resolve_hostname_queue_item, DEFVAL(IP::TYPE_ANY));
  	ClassDB::bind_method(D_METHOD("get_resolve_item_status", "id"), &IP::get_resolve_item_status);
  	ClassDB::bind_method(D_METHOD("get_resolve_item_address", "id"), &IP::get_resolve_item_address);
  	ClassDB::bind_method(D_METHOD("erase_resolve_item", "id"), &IP::erase_resolve_item);
  	ClassDB::bind_method(D_METHOD("get_local_addresses"), &IP::_get_local_addresses);
  	ClassDB::bind_method(D_METHOD("clear_cache", "hostname"), &IP::clear_cache, DEFVAL(""));
  
  	BIND_ENUM_CONSTANT(RESOLVER_STATUS_NONE);
  	BIND_ENUM_CONSTANT(RESOLVER_STATUS_WAITING);
  	BIND_ENUM_CONSTANT(RESOLVER_STATUS_DONE);
  	BIND_ENUM_CONSTANT(RESOLVER_STATUS_ERROR);
  
  	BIND_CONSTANT(RESOLVER_MAX_QUERIES);
  	BIND_CONSTANT(RESOLVER_INVALID_ID);
  
  	BIND_ENUM_CONSTANT(TYPE_NONE);
  	BIND_ENUM_CONSTANT(TYPE_IPV4);
  	BIND_ENUM_CONSTANT(TYPE_IPV6);
  	BIND_ENUM_CONSTANT(TYPE_ANY);
  }
  
  IP *IP::singleton = NULL;
  
  IP *IP::get_singleton() {
  
  	return singleton;
  }
  
  IP *(*IP::_create)() = NULL;
  
  IP *IP::create() {
  
  	ERR_FAIL_COND_V(singleton, NULL);
  	ERR_FAIL_COND_V(!_create, NULL);
  	return _create();
  }
  
  IP::IP() {
  
  	singleton = this;
  	resolver = memnew(_IP_ResolverPrivate);
  	resolver->sem = NULL;
  	resolver->mutex = Mutex::create();
  
  #ifndef NO_THREADS
  
  	resolver->sem = Semaphore::create();
  	if (resolver->sem) {
  		resolver->thread_abort = false;
  
  		resolver->thread = Thread::create(_IP_ResolverPrivate::_thread_function, resolver);
  
  		if (!resolver->thread)
  			memdelete(resolver->sem); //wtf
  	} else {
  		resolver->thread = NULL;
  	}
  #else
  	resolver->sem = NULL;
  	resolver->thread = NULL;
  #endif
  }
  
  IP::~IP() {
  
  #ifndef NO_THREADS
  	if (resolver->thread) {
  		resolver->thread_abort = true;
  		resolver->sem->post();
  		Thread::wait_to_finish(resolver->thread);
  		memdelete(resolver->thread);
  		memdelete(resolver->sem);
  	}
  
  #endif
  
  	memdelete(resolver->mutex);
  	memdelete(resolver);
  }
  