test: Add a unix socket connector test. Part of #1940

core/pom.xml

@@ -58,6 +58,12 @@
       <scope>test</scope>
     </dependency>
 
+    <dependency>
+      <groupId>com.github.jnr</groupId>
+      <artifactId>jnr-enxio</artifactId>
+      <version>0.32.17</version>
+    </dependency>
+
     <dependency>
       <groupId>com.github.jnr</groupId>
       <artifactId>jnr-unixsocket</artifactId>

core/src/test/java/com/google/cloud/sql/core/ConnectorTest.java

@@ -30,6 +30,8 @@
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.Socket;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Collections;
@@ -118,6 +120,43 @@ public void create_successfulPublicConnection() throws IOException, InterruptedE
     assertThat(readLine(socket)).isEqualTo(SERVER_MESSAGE);
   }
 
+  private boolean isWindows() {
+    String os = System.getProperty("os.name").toLowerCase();
+    return os.contains("win");
+  }
+
+  @Test
+  public void create_successfulUnixSocketConnection() throws IOException, InterruptedException {
+    if (isWindows()) {
+      System.out.println("Skipping unix socket test on Windows.");
+      return;
+    }
+
+    Path socketTestDir = Files.createTempDirectory("sockettest");
+    Path socketPath = socketTestDir.resolve("test.sock");
+    FakeUnixSocketServer unixSocketServer = new FakeUnixSocketServer(socketPath.toString());
+
+    try {
+
+      ConnectionConfig config =
+          new ConnectionConfig.Builder()
+              .withCloudSqlInstance("myProject:myRegion:myInstance")
+              .withIpTypes("PRIMARY")
+              .withUnixSocketPath(socketPath.toString())
+              .build();
+
+      unixSocketServer.start();
+
+      Connector connector = newConnector(config.getConnectorConfig(), 10000);
+
+      Socket socket = connector.connect(config, TEST_MAX_REFRESH_MS);
+
+      assertThat(readLine(socket)).isEqualTo(SERVER_MESSAGE);
+    } finally {
+      unixSocketServer.close();
+    }
+  }
+
   @Test
   public void create_successfulDomainScopedConnection() throws IOException, InterruptedException {
     FakeSslServer sslServer = new FakeSslServer();

core/src/test/java/com/google/cloud/sql/core/FakeUnixSocketServer.java

@@ -0,0 +1,128 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.cloud.sql.core;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.Selector;
+import java.util.Iterator;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicBoolean;
+import jnr.enxio.channels.NativeSelectorProvider;
+import jnr.unixsocket.UnixServerSocketChannel;
+import jnr.unixsocket.UnixSocketAddress;
+import jnr.unixsocket.UnixSocketChannel;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is a simple echo unix socket server adapted from the JNR socket project.
+ * https://github.com/jnr/jnr-unixsocket/blob/master/src/test/java/jnr/unixsocket/example/UnixServer.java
+ */
+class FakeUnixSocketServer {
+  private static Logger log = LoggerFactory.getLogger(FakeUnixSocketServer.class);
+  private final String path;
+  private final UnixSocketAddress address;
+  private UnixServerSocketChannel channel;
+  private final AtomicBoolean closed = new AtomicBoolean();
+
+  FakeUnixSocketServer(String path) {
+    this.path = path;
+    this.address = new UnixSocketAddress(path);
+  }
+
+  public void close() throws IOException {
+    this.closed.set(true);
+    channel.close();
+  }
+
+  public void start() throws IOException {
+    java.io.File path = new java.io.File(this.path);
+    path.deleteOnExit();
+
+    this.channel = UnixServerSocketChannel.open();
+    channel.configureBlocking(false);
+    channel.socket().bind(address);
+
+    Thread t = new Thread(this::run);
+    t.start();
+  }
+
+  public void run() {
+    log.info("Starting fake unix socket server at path " + this.path);
+    try {
+      Selector sel = NativeSelectorProvider.getInstance().openSelector();
+      channel.register(sel, SelectionKey.OP_ACCEPT, new ServerActor(channel));
+
+      log.info("Waiting for connections path " + this.path);
+      while (!this.closed.get()) {
+        if (sel.select() > 0) {
+          Set<SelectionKey> keys = sel.selectedKeys();
+          Iterator<SelectionKey> iterator = keys.iterator();
+          boolean running = false;
+          boolean cancelled = false;
+          while (iterator.hasNext()) {
+            SelectionKey k = iterator.next();
+            Actor a = (Actor) k.attachment();
+            if (a.rxready()) {
+              running = true;
+            } else {
+              k.cancel();
+              cancelled = true;
+            }
+            iterator.remove();
+          }
+          if (!running && cancelled) {
+            log.info("No Actors Running any more");
+            break;
+          }
+        }
+      }
+    } catch (IOException ex) {
+      log.info("IOException: waiting for sockets", ex);
+    }
+    log.info("UnixServer EXIT");
+  }
+
+  static interface Actor {
+    public boolean rxready();
+  }
+
+  static final class ServerActor implements Actor {
+    private final UnixServerSocketChannel channel;
+
+    public ServerActor(UnixServerSocketChannel channel) {
+      this.channel = channel;
+    }
+
+    @Override
+    public final boolean rxready() {
+      log.info("Handling unix socket connect.");
+      try {
+        UnixSocketChannel client = channel.accept();
+        client.configureBlocking(false);
+        ByteBuffer response = ByteBuffer.wrap("HELLO\n".getBytes("UTF-8"));
+        client.write(response);
+        log.info("Handling unix socket done.");
+        return true;
+      } catch (IOException ex) {
+        return false;
+      }
+    }
+  }
+}

pom.xml

@@ -569,7 +569,8 @@
                 com.google.auth:google-auth-library-credentials
 
                 Necessary for Unix socket support:
-                org.ow2.asm:asm-util AND com.github.jnr:jnr-unixsocket
+                org.ow2.asm:asm-util AND com.github.jnr:jnr-unixsocket AND
+                com.github.jnr:jnr-enxio
 
                 Necessary for Postgres support:
                 org.postgresql:postgresql
@@ -583,7 +584,7 @@
                 junit:junit,com.google.truth:truth,org.bouncycastle:bcpkix-jdk15on
                 com.google.cloud.sql:jdbc-socket-factory-core:test-jar
                 -->
-                org.ow2.asm:asm-util,com.github.jnr:jnr-unixsocket,org.postgresql:postgresql,junit:junit,com.google.truth:truth,com.microsoft.sqlserver:mssql-jdbc,com.google.guava:guava,org.bouncycastle:bcpkix-jdk15on,com.google.cloud.sql:jdbc-socket-factory-core:test-jar,com.google.auth:google-auth-library-credentials
+                org.ow2.asm:asm-util,com.github.jnr:jnr-unixsocket,com.github.jnr:jnr-enxio,org.postgresql:postgresql,junit:junit,com.google.truth:truth,com.microsoft.sqlserver:mssql-jdbc,com.google.guava:guava,org.bouncycastle:bcpkix-jdk15on,com.google.cloud.sql:jdbc-socket-factory-core:test-jar,com.google.auth:google-auth-library-credentials
               </ignoredDependencies>
             </configuration>
             <executions>