test: Fix tests on Java 21 or newer; add new InetAddress mocking code

Some unit tests work with fake ("mocked") InetAddress objects, which are
currently assembled via mockito. With Java 21 and newer, this is no
longer possible.

Replace the mocking code with a new "InetAddressMockery" class that can
provide real Inet4Address objects by means of Java object
deserialization.

Fixes #144

Signed-off-by: Christian Kohlschütter <[email protected]>

Author: kohlschuetter

core/src/test/java/org/dcache/nfs/InetAddressMatcherTest.java

@@ -27,6 +27,7 @@
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 
+import org.dcache.testutils.InetAddressMockery;
 import org.junit.Ignore;
 import org.junit.Test;
 
@@ -164,11 +165,6 @@ public void testDomainNoMatch() throws UnknownHostException {
     }
 
     private InetAddress mockInetAddress(String dnsName, String... ips) throws UnknownHostException {
-
-        InetAddress mockedAddress = mock(InetAddress.class);
-        given(mockedAddress.getHostName()).willReturn(dnsName);
-        given(mockedAddress.getCanonicalHostName()).willReturn(dnsName);
-
-        return mockedAddress;
+        return InetAddressMockery.mockedResolvedIPv4Address(dnsName, ips[0]);
     }
 }

core/src/test/java/org/dcache/testutils/InetAddressBuilder.java

@@ -2,8 +2,6 @@
 
 import java.net.InetAddress;
 
-import org.mockito.Mockito;
-
 public class InetAddressBuilder {
     private String ipAddress;
     private String hostName;
@@ -19,9 +17,6 @@ public InetAddressBuilder hostName(String hostName) {
     }
 
     public InetAddress build() {
-        InetAddress address = Mockito.mock(InetAddress.class);
-        Mockito.when(address.getHostAddress()).thenReturn(ipAddress);
-        Mockito.when(address.getHostName()).thenReturn(hostName);
-        return address;
+        return InetAddressMockery.mockedResolvedIPv4Address(hostName, ipAddress);
     }
 }

core/src/test/java/org/dcache/testutils/InetAddressMockery.java

@@ -0,0 +1,108 @@
+package org.dcache.testutils;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectStreamConstants;
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Creates InetAddress objects that contain arbitrary hostname/address combinations.
+ * 
+ * @author Christian Kohlschütter
+ */
+public final class InetAddressMockery {
+    private InetAddressMockery() {
+        throw new IllegalStateException("No instances");
+    }
+
+    /**
+     * Returns a "resolved" Inet4Address using the given hostname and IPv4 address.
+     * 
+     * @param hostname The hostname.
+     * @param ip4Address The IPv4 address (e.g. "1.2.3.4").
+     * @return The Inet4Address object.
+     * @throws IllegalStateException on internal error.
+     */
+    public static InetAddress mockedResolvedIPv4Address(String hostname, String ip4Address) {
+        byte[] addr;
+        try {
+            addr = ((Inet4Address) InetAddress.getByName(ip4Address)).getAddress();
+        } catch (UnknownHostException e) {
+            throw new IllegalStateException(e);
+        }
+        int ipv4Addr = ((addr[0]) << 24 & 0xFF000000) | (addr[1] << 16 & 0xFF0000)
+                | (addr[2] << 8 & 0xFF00) | (addr[3] & 0xFF);
+        return mockedResolvedIPv4Address(hostname, ipv4Addr);
+    }
+
+    /**
+     * Returns a "resolved" Inet4Address using the given hostname and IPv4 address.
+     * 
+     * @param hostname The hostname.
+     * @param ip4Address The IPv4 address (e.g. {@code 0x01020304})
+     * @return The Inet4Address object.
+     * @throws IllegalStateException on internal error.
+     */
+    public static InetAddress mockedResolvedIPv4Address(String hostname, int ip4Address) {
+        try (ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(serializeIp4(hostname,
+                ip4Address)))) {
+            return (InetAddress) in.readObject();
+        } catch (ClassNotFoundException | IOException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    private static byte[] serializeIp4(String hostname, int address) {
+        ByteBuffer bb = ByteBuffer.allocate(512);
+        bb.putShort(ObjectStreamConstants.STREAM_MAGIC); // STREAM_MAGIC
+        bb.putShort((short) 5); // STREAM_VERSION (hard-coded)
+        bb.put(ObjectStreamConstants.TC_OBJECT);
+        bb.put(ObjectStreamConstants.TC_CLASSDESC);
+
+        putShortLengthUtf8(bb, InetAddress.class.getName());
+        bb.putLong(3286316764910316507L); // InetAddress serialVersionUID
+        bb.put((byte) 0x03); // class type descriptor
+        bb.putShort((short) 3); // 3 fields
+
+        bb.put((byte) 0x49);
+        putShortLengthUtf8(bb, "address");
+
+        bb.put((byte) 0x49);
+        putShortLengthUtf8(bb, "family");
+
+        bb.put((byte) 0x4c);
+        putShortLengthUtf8(bb, "hostName");
+
+        bb.put(ObjectStreamConstants.TC_STRING);
+        putShortLengthEncodedClassName(bb, String.class);
+        bb.put(ObjectStreamConstants.TC_ENDBLOCKDATA);
+
+        bb.put(ObjectStreamConstants.TC_BASE);
+        bb.putInt(address);
+        bb.putInt(0x00000001); // IPv4
+        bb.put(ObjectStreamConstants.TC_STRING);
+        putShortLengthUtf8(bb, hostname);
+
+        bb.put(ObjectStreamConstants.TC_ENDBLOCKDATA);
+        bb.flip();
+
+        byte[] buf = new byte[bb.remaining()];
+        bb.get(buf);
+        return buf;
+    }
+
+    private static void putShortLengthEncodedClassName(ByteBuffer bb, Class<?> klazz) {
+        putShortLengthUtf8(bb, "L" + klazz.getName().replace('.', '/') + ";");
+    }
+
+    private static void putShortLengthUtf8(ByteBuffer bb, String s) {
+        byte[] utf8 = s.getBytes(StandardCharsets.UTF_8);
+        bb.putShort((short) utf8.length);
+        bb.put(utf8);
+    }
+}