godot/core/io/ip.cpp
Fabio Alessandrelli 811ea6ad64
[Net] Fix IP address resolution incorrectly locking the main thread.
This seems to be a pretty old bug, older then originally reported (at
least under certain circumstances).

The IP singleton uses a resolve queue so developers can queue hostnames
for resolution in a separate while keeping the main thread unlocked
(address-resolution OS functions are blocking, and could block for a long
time in case of network disruption).

In most places though, the address resolution function was called with
the mutex locked, causing other functions (querying status, queueing
another hostname, ecc) to block until that resolution ended.

This commit ensures that all calls to OS address resolution are done
with the mutex unlocked.

(cherry picked from commit aca5540e13)
2021-08-03 14:33:42 +02:00

374 lines
12 KiB
C++

/*************************************************************************/
/* ip.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2021 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 "core/hash_map.h"
#include "core/os/semaphore.h"
#include "core/os/thread.h"
VARIANT_ENUM_CAST(IP::ResolverStatus);
/************* RESOLVER ******************/
struct _IP_ResolverPrivate {
struct QueueItem {
SafeNumeric<IP::ResolverStatus> status;
List<IP_Address> response;
String hostname;
IP::Type type;
void clear() {
status.set(IP::RESOLVER_STATUS_NONE);
response.clear();
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.get() == 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.get() != IP::RESOLVER_STATUS_WAITING) {
continue;
}
mutex.lock();
List<IP_Address> response;
String hostname = queue[i].hostname;
IP::Type type = queue[i].type;
mutex.unlock();
// We should not lock while resolving the hostname,
// only when modifying the queue.
IP::get_singleton()->_resolve_hostname(response, hostname, type);
MutexLock lock(mutex);
// Could have been completed by another function, or deleted.
if (queue[i].status.get() != IP::RESOLVER_STATUS_WAITING) {
continue;
}
queue[i].response = response;
queue[i].status.set(response.empty() ? IP::RESOLVER_STATUS_ERROR : IP::RESOLVER_STATUS_DONE);
}
}
static void _thread_function(void *self) {
_IP_ResolverPrivate *ipr = (_IP_ResolverPrivate *)self;
while (!ipr->thread_abort) {
ipr->sem.wait();
ipr->resolve_queues();
}
}
HashMap<String, List<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) {
List<IP_Address> res;
String key = _IP_ResolverPrivate::get_cache_key(p_hostname, p_type);
resolver->mutex.lock();
if (resolver->cache.has(key)) {
res = resolver->cache[key];
} else {
// This should be run unlocked so the resolver thread can keep
// resolving other requests.
resolver->mutex.unlock();
_resolve_hostname(res, p_hostname, p_type);
resolver->mutex.lock();
// We might be overriding another result, but we don't care (they are the
// same hostname).
resolver->cache[key] = res;
}
resolver->mutex.unlock();
for (int i = 0; i < res.size(); ++i) {
if (res[i].is_valid()) {
return res[i];
}
}
return IP_Address();
}
Array IP::resolve_hostname_addresses(const String &p_hostname, Type p_type) {
List<IP_Address> res;
String key = _IP_ResolverPrivate::get_cache_key(p_hostname, p_type);
resolver->mutex.lock();
if (resolver->cache.has(key)) {
res = resolver->cache[key];
} else {
// This should be run unlocked so the resolver thread can keep resolving
// other requests.
resolver->mutex.unlock();
_resolve_hostname(res, p_hostname, p_type);
resolver->mutex.lock();
// We might be overriding another result, but we don't care (they are the
// same hostname).
resolver->cache[key] = res;
}
resolver->mutex.unlock();
Array result;
for (int i = 0; i < res.size(); ++i) {
if (res[i].is_valid()) {
result.push_back(String(res[i]));
}
}
return result;
}
IP::ResolverID IP::resolve_hostname_queue_item(const String &p_hostname, IP::Type p_type) {
MutexLock lock(resolver->mutex);
ResolverID id = resolver->find_empty_id();
if (id == RESOLVER_INVALID_ID) {
WARN_PRINT("Out of resolver queries");
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->queue[id].response = resolver->cache[key];
resolver->queue[id].status.set(IP::RESOLVER_STATUS_DONE);
} else {
resolver->queue[id].response = List<IP_Address>();
resolver->queue[id].status.set(IP::RESOLVER_STATUS_WAITING);
if (resolver->thread.is_started()) {
resolver->sem.post();
} else {
resolver->resolve_queues();
}
}
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);
IP::ResolverStatus res = resolver->queue[p_id].status.get();
if (res == IP::RESOLVER_STATUS_NONE) {
ERR_PRINT("Condition status == IP::RESOLVER_STATUS_NONE");
return IP::RESOLVER_STATUS_NONE;
}
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());
MutexLock lock(resolver->mutex);
if (resolver->queue[p_id].status.get() != IP::RESOLVER_STATUS_DONE) {
ERR_PRINT("Resolve of '" + resolver->queue[p_id].hostname + "'' didn't complete yet.");
return IP_Address();
}
List<IP_Address> res = resolver->queue[p_id].response;
for (int i = 0; i < res.size(); ++i) {
if (res[i].is_valid()) {
return res[i];
}
}
return IP_Address();
}
Array IP::get_resolve_item_addresses(ResolverID p_id) const {
ERR_FAIL_INDEX_V(p_id, IP::RESOLVER_MAX_QUERIES, Array());
MutexLock lock(resolver->mutex);
if (resolver->queue[p_id].status.get() != IP::RESOLVER_STATUS_DONE) {
ERR_PRINT("Resolve of '" + resolver->queue[p_id].hostname + "'' didn't complete yet.");
return Array();
}
List<IP_Address> res = resolver->queue[p_id].response;
Array result;
for (int i = 0; i < res.size(); ++i) {
if (res[i].is_valid()) {
result.push_back(String(res[i]));
}
}
return result;
}
void IP::erase_resolve_item(ResolverID p_id) {
ERR_FAIL_INDEX(p_id, IP::RESOLVER_MAX_QUERIES);
resolver->queue[p_id].status.set(IP::RESOLVER_STATUS_NONE);
}
void IP::clear_cache(const String &p_hostname) {
MutexLock lock(resolver->mutex);
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));
}
}
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;
}
Array IP::_get_local_interfaces() const {
Array results;
Map<String, Interface_Info> interfaces;
get_local_interfaces(&interfaces);
for (Map<String, Interface_Info>::Element *E = interfaces.front(); E; E = E->next()) {
Interface_Info &c = E->get();
Dictionary rc;
rc["name"] = c.name;
rc["friendly"] = c.name_friendly;
rc["index"] = c.index;
Array ips;
for (const List<IP_Address>::Element *F = c.ip_addresses.front(); F; F = F->next()) {
ips.push_front(F->get());
}
rc["addresses"] = ips;
results.push_front(rc);
}
return results;
}
void IP::get_local_addresses(List<IP_Address> *r_addresses) const {
Map<String, Interface_Info> interfaces;
get_local_interfaces(&interfaces);
for (Map<String, Interface_Info>::Element *E = interfaces.front(); E; E = E->next()) {
for (const List<IP_Address>::Element *F = E->get().ip_addresses.front(); F; F = F->next()) {
r_addresses->push_front(F->get());
}
}
}
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_addresses", "host", "ip_type"), &IP::resolve_hostname_addresses, 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("get_resolve_item_addresses", "id"), &IP::get_resolve_item_addresses);
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("get_local_interfaces"), &IP::_get_local_interfaces);
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 = nullptr;
IP *IP::get_singleton() {
return singleton;
}
IP *(*IP::_create)() = nullptr;
IP *IP::create() {
ERR_FAIL_COND_V_MSG(singleton, nullptr, "IP singleton already exist.");
ERR_FAIL_COND_V(!_create, nullptr);
return _create();
}
IP::IP() {
singleton = this;
resolver = memnew(_IP_ResolverPrivate);
resolver->thread_abort = false;
resolver->thread.start(_IP_ResolverPrivate::_thread_function, resolver);
}
IP::~IP() {
resolver->thread_abort = true;
resolver->sem.post();
resolver->thread.wait_to_finish();
memdelete(resolver);
}