Core: Add UNIX domain socket support

> [!NOTE]
>
> Later versions of Windows has support for `AF_UNIX`, so it could be
> added.

tests/core/io/test_uds_server.h

@@ -0,0 +1,302 @@
+/**************************************************************************/
+/*  test_uds_server.h                                                     */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* 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.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "core/io/file_access.h"
+#include "core/io/stream_peer_uds.h"
+#include "core/io/uds_server.h"
+#include "tests/test_macros.h"
+
+#include <functional>
+
+namespace TestUDSServer {
+
+#ifdef UNIX_ENABLED
+
+const String SOCKET_PATH = "/tmp/godot_test_uds_socket";
+const uint32_t SLEEP_DURATION = 1000;
+const uint64_t MAX_WAIT_USEC = 2000000;
+
+void wait_for_condition(std::function<bool()> f_test) {
+	const uint64_t time = OS::get_singleton()->get_ticks_usec();
+	while (!f_test() && (OS::get_singleton()->get_ticks_usec() - time) < MAX_WAIT_USEC) {
+		OS::get_singleton()->delay_usec(SLEEP_DURATION);
+	}
+}
+
+void cleanup_socket_file() {
+	// Remove socket file if it exists
+	if (FileAccess::exists(SOCKET_PATH)) {
+		DirAccess::remove_absolute(SOCKET_PATH);
+	}
+}
+
+Ref<UDSServer> create_server(const String &p_path) {
+	cleanup_socket_file();
+
+	Ref<UDSServer> server;
+	server.instantiate();
+
+	REQUIRE_EQ(server->listen(p_path), Error::OK);
+	REQUIRE(server->is_listening());
+	CHECK_FALSE(server->is_connection_available());
+
+	return server;
+}
+
+Ref<StreamPeerUDS> create_client(const String &p_path) {
+	Ref<StreamPeerUDS> client;
+	client.instantiate();
+
+	Error err = client->connect_to_host(p_path);
+	REQUIRE_EQ(err, Error::OK);
+
+	// UDS connections may be immediately connected or in connecting state
+	StreamPeerUDS::Status status = client->get_status();
+	REQUIRE((status == StreamPeerUDS::STATUS_CONNECTED || status == StreamPeerUDS::STATUS_CONNECTING));
+
+	if (status == StreamPeerUDS::STATUS_CONNECTED) {
+		CHECK_EQ(client->get_connected_path(), p_path);
+	}
+
+	return client;
+}
+
+Ref<StreamPeerUDS> accept_connection(Ref<UDSServer> &p_server) {
+	wait_for_condition([&]() {
+		return p_server->is_connection_available();
+	});
+
+	REQUIRE(p_server->is_connection_available());
+	Ref<StreamPeerUDS> client_from_server = p_server->take_connection();
+	REQUIRE(client_from_server.is_valid());
+	CHECK_EQ(client_from_server->get_status(), StreamPeerUDS::STATUS_CONNECTED);
+
+	return client_from_server;
+}
+
+TEST_CASE("[UDSServer] Instantiation") {
+	Ref<UDSServer> server;
+	server.instantiate();
+
+	REQUIRE(server.is_valid());
+	CHECK_FALSE(server->is_listening());
+}
+
+TEST_CASE("[UDSServer] Accept a connection and receive/send data") {
+	Ref<UDSServer> server = create_server(SOCKET_PATH);
+	Ref<StreamPeerUDS> client = create_client(SOCKET_PATH);
+	Ref<StreamPeerUDS> client_from_server = accept_connection(server);
+
+	wait_for_condition([&]() {
+		return client->poll() != Error::OK || client->get_status() == StreamPeerUDS::STATUS_CONNECTED;
+	});
+
+	CHECK_EQ(client->get_status(), StreamPeerUDS::STATUS_CONNECTED);
+
+	// Sending data from client to server.
+	const String hello_world = "Hello World!";
+	client->put_string(hello_world);
+	CHECK_EQ(client_from_server->get_string(), hello_world);
+
+	// Sending data from server to client.
+	const float pi = 3.1415;
+	client_from_server->put_float(pi);
+	CHECK_EQ(client->get_float(), pi);
+
+	client->disconnect_from_host();
+	server->stop();
+	CHECK_FALSE(server->is_listening());
+
+	cleanup_socket_file();
+}
+
+TEST_CASE("[UDSServer] Handle multiple clients at the same time") {
+	Ref<UDSServer> server = create_server(SOCKET_PATH);
+
+	Vector<Ref<StreamPeerUDS>> clients;
+	for (int i = 0; i < 5; i++) {
+		clients.push_back(create_client(SOCKET_PATH));
+	}
+
+	Vector<Ref<StreamPeerUDS>> clients_from_server;
+	for (int i = 0; i < clients.size(); i++) {
+		clients_from_server.push_back(accept_connection(server));
+	}
+
+	wait_for_condition([&]() {
+		bool should_exit = true;
+		for (Ref<StreamPeerUDS> &c : clients) {
+			if (c->poll() != Error::OK) {
+				return true;
+			}
+			StreamPeerUDS::Status status = c->get_status();
+			if (status != StreamPeerUDS::STATUS_CONNECTED && status != StreamPeerUDS::STATUS_CONNECTING) {
+				return true;
+			}
+			if (status != StreamPeerUDS::STATUS_CONNECTED) {
+				should_exit = false;
+			}
+		}
+		return should_exit;
+	});
+
+	for (Ref<StreamPeerUDS> &c : clients) {
+		REQUIRE_EQ(c->get_status(), StreamPeerUDS::STATUS_CONNECTED);
+	}
+
+	// Sending data from each client to server.
+	for (int i = 0; i < clients.size(); i++) {
+		String hello_client = "Hello " + itos(i);
+		clients[i]->put_string(hello_client);
+		CHECK_EQ(clients_from_server[i]->get_string(), hello_client);
+	}
+
+	for (Ref<StreamPeerUDS> &c : clients) {
+		c->disconnect_from_host();
+	}
+	server->stop();
+
+	cleanup_socket_file();
+}
+
+TEST_CASE("[UDSServer] When stopped shouldn't accept new connections") {
+	Ref<UDSServer> server = create_server(SOCKET_PATH);
+	Ref<StreamPeerUDS> client = create_client(SOCKET_PATH);
+	Ref<StreamPeerUDS> client_from_server = accept_connection(server);
+
+	wait_for_condition([&]() {
+		return client->poll() != Error::OK || client->get_status() == StreamPeerUDS::STATUS_CONNECTED;
+	});
+
+	CHECK_EQ(client->get_status(), StreamPeerUDS::STATUS_CONNECTED);
+
+	// Sending data from client to server.
+	const String hello_world = "Hello World!";
+	client->put_string(hello_world);
+	CHECK_EQ(client_from_server->get_string(), hello_world);
+
+	client->disconnect_from_host();
+	server->stop();
+	CHECK_FALSE(server->is_listening());
+
+	// Clean up the socket file after server stops
+	cleanup_socket_file();
+
+	// Try to connect to non-existent socket
+	Ref<StreamPeerUDS> new_client;
+	new_client.instantiate();
+	Error err = new_client->connect_to_host(SOCKET_PATH);
+
+	// Connection should fail since socket doesn't exist
+	CHECK_NE(err, Error::OK);
+	CHECK_FALSE(server->is_connection_available());
+
+	cleanup_socket_file();
+}
+
+TEST_CASE("[UDSServer] Should disconnect client") {
+	Ref<UDSServer> server = create_server(SOCKET_PATH);
+	Ref<StreamPeerUDS> client = create_client(SOCKET_PATH);
+	Ref<StreamPeerUDS> client_from_server = accept_connection(server);
+
+	wait_for_condition([&]() {
+		return client->poll() != Error::OK || client->get_status() == StreamPeerUDS::STATUS_CONNECTED;
+	});
+
+	CHECK_EQ(client->get_status(), StreamPeerUDS::STATUS_CONNECTED);
+
+	// Sending data from client to server.
+	const String hello_world = "Hello World!";
+	client->put_string(hello_world);
+	CHECK_EQ(client_from_server->get_string(), hello_world);
+
+	client_from_server->disconnect_from_host();
+	server->stop();
+	CHECK_FALSE(server->is_listening());
+
+	// Wait for disconnection
+	wait_for_condition([&]() {
+		return client->poll() != Error::OK || client->get_status() == StreamPeerUDS::STATUS_NONE;
+	});
+
+	// Wait for disconnection
+	wait_for_condition([&]() {
+		return client_from_server->poll() != Error::OK || client_from_server->get_status() == StreamPeerUDS::STATUS_NONE;
+	});
+
+	CHECK_EQ(client->get_status(), StreamPeerUDS::STATUS_NONE);
+	CHECK_EQ(client_from_server->get_status(), StreamPeerUDS::STATUS_NONE);
+
+	ERR_PRINT_OFF;
+	CHECK_EQ(client->get_string(), String());
+	CHECK_EQ(client_from_server->get_string(), String());
+	ERR_PRINT_ON;
+
+	cleanup_socket_file();
+}
+
+TEST_CASE("[UDSServer] Test with different socket paths") {
+	// Test with a different socket path
+	const String alt_socket_path = "/tmp/godot_test_uds_socket_alt";
+
+	// Clean up before test
+	if (FileAccess::exists(alt_socket_path)) {
+		DirAccess::remove_absolute(alt_socket_path);
+	}
+
+	Ref<UDSServer> server = create_server(alt_socket_path);
+	Ref<StreamPeerUDS> client = create_client(alt_socket_path);
+	Ref<StreamPeerUDS> client_from_server = accept_connection(server);
+
+	wait_for_condition([&]() {
+		return client->poll() != Error::OK || client->get_status() == StreamPeerUDS::STATUS_CONNECTED;
+	});
+
+	CHECK_EQ(client->get_status(), StreamPeerUDS::STATUS_CONNECTED);
+
+	// Test data exchange
+	const int test_number = 42;
+	client->put_32(test_number);
+	CHECK_EQ(client_from_server->get_32(), test_number);
+
+	client->disconnect_from_host();
+	server->stop();
+
+	// Clean up
+	if (FileAccess::exists(alt_socket_path)) {
+		DirAccess::remove_absolute(alt_socket_path);
+	}
+}
+
+#endif
+
+} // namespace TestUDSServer

tests/test_main.cpp

@@ -62,6 +62,7 @@
 #include "tests/core/io/test_stream_peer_gzip.h"
 #include "tests/core/io/test_tcp_server.h"
 #include "tests/core/io/test_udp_server.h"
+#include "tests/core/io/test_uds_server.h"
 #include "tests/core/io/test_xml_parser.h"
 #include "tests/core/math/test_aabb.h"
 #include "tests/core/math/test_astar.h"