Simplify JarFileUrlKey to prevent issues with Cortex XDR agent

Replace the string based `JarFileUrlKey` and cache with a simple key
built directly from URL components. This should allow cache lookups
to remain fast whilst removing any `URLStreamHandler.getHostAddress`
calls.

Prior to this commit, we assumed that it was safe to use the URL
directly as a cache key as long as it had an empty or null `host`.
This assumption isn't correct when Palo Alto Network Cortex XDR agent
is present as it appears to intercept calls to `getHostAddress`
and, unlike the JDK code, always perform a DNS lookup.

Fixes gh-46401

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/net/protocol/jar/Handler.java

@@ -183,7 +183,6 @@ public class Handler extends URLStreamHandler {
 	 * Clear any internal caches.
 	 */
 	public static void clearCache() {
-		JarFileUrlKey.clearCache();
 		JarUrlConnection.clearCache();
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/net/protocol/jar/JarFileUrlKey.java

@@ -16,68 +16,56 @@
 
 package org.springframework.boot.loader.net.protocol.jar;
 
-import java.lang.ref.SoftReference;
 import java.net.URL;
-import java.util.Locale;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
+import java.util.Objects;
 
 /**
- * Utility to generate a string key from a jar file {@link URL} that can be used as a
- * cache key.
+ * A fast cache key for a jar file {@link URL} that doesn't trigger DNS lookups.
  *
  * @author Phillip Webb
  */
 final class JarFileUrlKey {
 
-	private static volatile SoftReference<Map<URL, String>> cache;
+	private final String protocol;
 
-	private JarFileUrlKey() {
-	}
+	private final String host;
 
-	/**
-	 * Get the {@link JarFileUrlKey} for the given URL.
-	 * @param url the source URL
-	 * @return a {@link JarFileUrlKey} instance
-	 */
-	static String get(URL url) {
-		if (!isCachableUrl(url)) {
-			return create(url);
-		}
-		Map<URL, String> cache = (JarFileUrlKey.cache != null) ? JarFileUrlKey.cache.get() : null;
-		if (cache == null) {
-			cache = new ConcurrentHashMap<>();
-			JarFileUrlKey.cache = new SoftReference<>(cache);
-		}
-		return cache.computeIfAbsent(url, JarFileUrlKey::create);
+	private final int port;
+
+	private final String file;
+
+	private final boolean runtimeRef;
+
+	JarFileUrlKey(URL url) {
+		this.protocol = url.getProtocol();
+		this.host = url.getHost();
+		this.port = (url.getPort() != -1) ? url.getPort() : url.getDefaultPort();
+		this.file = url.getFile();
+		this.runtimeRef = "runtime".equals(url.getRef());
 	}
 
-	private static boolean isCachableUrl(URL url) {
-		// Don't cache URL that have a host since equals() will perform DNS lookup
-		return url.getHost() == null || url.getHost().isEmpty();
+	@Override
+	public int hashCode() {
+		return Objects.hashCode(this.file);
 	}
 
-	private static String create(URL url) {
-		StringBuilder value = new StringBuilder();
-		String protocol = url.getProtocol();
-		String host = url.getHost();
-		int port = (url.getPort() != -1) ? url.getPort() : url.getDefaultPort();
-		String file = url.getFile();
-		value.append(protocol.toLowerCase(Locale.ROOT));
-		value.append(":");
-		if (host != null && !host.isEmpty()) {
-			value.append(host.toLowerCase(Locale.ROOT));
-			value.append((port != -1) ? ":" + port : "");
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
 		}
-		value.append((file != null) ? file : "");
-		if ("runtime".equals(url.getRef())) {
-			value.append("#runtime");
+		if (obj == null || getClass() != obj.getClass()) {
+			return false;
 		}
-		return value.toString();
+		JarFileUrlKey other = (JarFileUrlKey) obj;
+		// We check file first as case sensitive and the most likely item to be different
+		return Objects.equals(this.file, other.file) && equalsIgnoringCase(this.protocol, other.protocol)
+				&& equalsIgnoringCase(this.host, other.host) && (this.port == other.port)
+				&& (this.runtimeRef == other.runtimeRef);
 	}
 
-	static void clearCache() {
-		cache = null;
+	private boolean equalsIgnoringCase(String s1, String s2) {
+		return (s1 == s2) || (s1 != null && s1.equalsIgnoreCase(s2));
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/net/protocol/jar/UrlJarFiles.java

@@ -144,7 +144,7 @@ class UrlJarFiles {
 	 */
 	private static final class Cache {
 
-		private final Map<String, JarFile> jarFileUrlToJarFile = new HashMap<>();
+		private final Map<JarFileUrlKey, JarFile> jarFileUrlToJarFile = new HashMap<>();
 
 		private final Map<JarFile, URL> jarFileToJarFileUrl = new HashMap<>();
 
@@ -154,7 +154,7 @@ class UrlJarFiles {
 		 * @return the cached {@link JarFile} or {@code null}
 		 */
 		JarFile get(URL jarFileUrl) {
-			String urlKey = JarFileUrlKey.get(jarFileUrl);
+			JarFileUrlKey urlKey = new JarFileUrlKey(jarFileUrl);
 			synchronized (this) {
 				return this.jarFileUrlToJarFile.get(urlKey);
 			}
@@ -180,7 +180,7 @@ class UrlJarFiles {
 		 * they were already there
 		 */
 		boolean putIfAbsent(URL jarFileUrl, JarFile jarFile) {
-			String urlKey = JarFileUrlKey.get(jarFileUrl);
+			JarFileUrlKey urlKey = new JarFileUrlKey(jarFileUrl);
 			synchronized (this) {
 				JarFile cached = this.jarFileUrlToJarFile.get(urlKey);
 				if (cached == null) {
@@ -200,7 +200,7 @@ class UrlJarFiles {
 			synchronized (this) {
 				URL removedUrl = this.jarFileToJarFileUrl.remove(jarFile);
 				if (removedUrl != null) {
-					this.jarFileUrlToJarFile.remove(JarFileUrlKey.get(removedUrl));
+					this.jarFileUrlToJarFile.remove(new JarFileUrlKey(removedUrl));
 				}
 			}
 		}

spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/net/protocol/jar/JarFileUrlKeyTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.loader.net.protocol.jar;
 
+import java.net.MalformedURLException;
 import java.net.URL;
 
 import org.junit.jupiter.api.BeforeAll;
@@ -38,51 +39,66 @@ class JarFileUrlKeyTests {
 	}
 
 	@Test
-	void getCreatesKey() throws Exception {
-		URL url = new URL("jar:nested:/my.jar/!mynested.jar!/my/path");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("jar:nested:/my.jar/!mynested.jar!/my/path");
+	void equalsAndHashCode() throws Exception {
+		JarFileUrlKey k1 = key("jar:nested:/my.jar/!mynested.jar!/my/path");
+		JarFileUrlKey k2 = key("jar:nested:/my.jar/!mynested.jar!/my/path");
+		JarFileUrlKey k3 = key("jar:nested:/my.jar/!mynested.jar!/my/path2");
+		assertThat(k1.hashCode()).isEqualTo(k2.hashCode())
+			.isEqualTo("nested:/my.jar/!mynested.jar!/my/path".hashCode());
+		assertThat(k1).isEqualTo(k1).isEqualTo(k2).isNotEqualTo(k3);
 	}
 
 	@Test
-	void getWhenUppercaseProtocolCreatesKey() throws Exception {
-		URL url = new URL("JAR:nested:/my.jar/!mynested.jar!/my/path");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("jar:nested:/my.jar/!mynested.jar!/my/path");
+	void equalsWhenUppercaseAndLowercaseProtocol() throws Exception {
+		JarFileUrlKey k1 = key("JAR:nested:/my.jar/!mynested.jar!/my/path");
+		JarFileUrlKey k2 = key("jar:nested:/my.jar/!mynested.jar!/my/path");
+		assertThat(k1).isEqualTo(k2);
 	}
 
 	@Test
-	void getWhenHasHostAndPortCreatesKey() throws Exception {
-		URL url = new URL("https://example.com:1234/test");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("https:example.com:1234/test");
+	void equalsWhenHasHostAndPort() throws Exception {
+		JarFileUrlKey k1 = key("https://example.com:1234/test");
+		JarFileUrlKey k2 = key("https://example.com:1234/test");
+		assertThat(k1).isEqualTo(k2);
 	}
 
 	@Test
-	void getWhenHasUppercaseHostCreatesKey() throws Exception {
-		URL url = new URL("https://EXAMPLE.com:1234/test");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("https:example.com:1234/test");
+	void equalsWhenHasUppercaseAndLowercaseHost() throws Exception {
+		JarFileUrlKey k1 = key("https://EXAMPLE.com:1234/test");
+		JarFileUrlKey k2 = key("https://example.com:1234/test");
+		assertThat(k1).isEqualTo(k2);
 	}
 
 	@Test
-	void getWhenHasNoPortCreatesKeyWithDefaultPort() throws Exception {
-		URL url = new URL("https://EXAMPLE.com/test");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("https:example.com:443/test");
+	void equalsWhenHasNoPortUsesDefaultPort() throws Exception {
+		JarFileUrlKey k1 = key("https://EXAMPLE.com/test");
+		JarFileUrlKey k2 = key("https://example.com:443/test");
+		assertThat(k1).isEqualTo(k2);
 	}
 
 	@Test
-	void getWhenHasNoFileCreatesKey() throws Exception {
-		URL url = new URL("https://EXAMPLE.com");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("https:example.com:443");
+	void equalsWhenHasNoFile() throws Exception {
+		JarFileUrlKey k1 = key("https://EXAMPLE.com");
+		JarFileUrlKey k2 = key("https://example.com:443");
+		assertThat(k1).isEqualTo(k2);
 	}
 
 	@Test
-	void getWhenHasRuntimeRefCreatesKey() throws Exception {
-		URL url = new URL("jar:nested:/my.jar/!mynested.jar!/my/path#runtime");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("jar:nested:/my.jar/!mynested.jar!/my/path#runtime");
+	void equalsWhenHasRuntimeRef() throws Exception {
+		JarFileUrlKey k1 = key("jar:nested:/my.jar/!mynested.jar!/my/path#runtime");
+		JarFileUrlKey k2 = key("jar:nested:/my.jar/!mynested.jar!/my/path#runtime");
+		assertThat(k1).isEqualTo(k2);
 	}
 
 	@Test
-	void getWhenHasOtherRefCreatesKeyWithoutRef() throws Exception {
-		URL url = new URL("jar:nested:/my.jar/!mynested.jar!/my/path#example");
-		assertThat(JarFileUrlKey.get(url)).isEqualTo("jar:nested:/my.jar/!mynested.jar!/my/path");
+	void equalsWhenHasOtherRefIgnoresRefs() throws Exception {
+		JarFileUrlKey k1 = key("jar:nested:/my.jar/!mynested.jar!/my/path#example");
+		JarFileUrlKey k2 = key("jar:nested:/my.jar/!mynested.jar!/my/path");
+		assertThat(k1).isEqualTo(k2);
+	}
+
+	private JarFileUrlKey key(String spec) throws MalformedURLException {
+		return new JarFileUrlKey(new URL(spec));
 	}
 
 }