Enable new TcpKeepAlive options on Java 8

This change sets the new KeepAlive-related options directly through the
JDK, instead of going through `SocketSupport`. There are two reasons for
this.

First, the `SocketSupport` code path doesn't work on Java 8, as it
attempts to reflectively call `Socket.setOption()`, which was added in
newer versions.

Second, the options themselves _do_ exist on Java 8. The Java socket
options were backported to Java 8 in 8u261 (July 2020):

https://bugs.java.com/bugdatabase/view_bug.do?bug_id=8194298

As for Windows, it supports `TCP_KEEPIDLE` and `TCP_KEEPINTVL` since
Windows 10 version 1709 (October 2017):

https://learn.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options

I think it's safe at this point to simply use these features like any
other socket option. Unfortunately, it doesn't look like Mojo signatures
are distributed for newer maintenance releases of Java 8, so I've had to
update `hc.animal-sniffer.signature.ignores`.

Finally, I've added test coverage in TestTlsHandshakeTimeout to exercise
this feature, as well as to assert that KeepAlive doesn't interfere with
socket timeouts.

Author: rschmitt

httpclient5-testing/src/test/java/org/apache/hc/client5/testing/sync/TestTlsHandshakeTimeout.java

@@ -42,6 +42,7 @@
 import org.apache.hc.client5.testing.SSLTestContexts;
 import org.apache.hc.client5.testing.tls.TlsHandshakeTimeoutServer;
 import org.apache.hc.core5.http.ClassicHttpRequest;
+import org.apache.hc.core5.http.io.SocketConfig;
 import org.junit.jupiter.api.Timeout;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
@@ -71,6 +72,11 @@ void testTimeout(final boolean sendServerHello) throws Exception {
                 .setConnectTimeout(5, SECONDS)
                 .setSocketTimeout(5, SECONDS)
                 .build())
+            .setDefaultSocketConfig(SocketConfig.custom()
+                .setTcpKeepIdle(2)
+                .setTcpKeepInterval(1)
+                .setTcpKeepCount(5)
+                .build())
             .setTlsSocketStrategy(new DefaultClientTlsStrategy(SSLTestContexts.createClientSSLContext(), HostnameVerificationPolicy.CLIENT, NoopHostnameVerifier.INSTANCE))
             .setDefaultTlsConfig(TlsConfig.custom()
                 .setHandshakeTimeout(EXPECTED_TIMEOUT.toMillis(), MILLISECONDS)

httpclient5/src/main/java/org/apache/hc/client5/http/impl/io/DefaultHttpClientConnectionOperator.java

@@ -36,6 +36,8 @@
 import java.util.Collections;
 import java.util.List;
 
+import jdk.net.ExtendedSocketOptions;
+import jdk.net.Sockets;
 import org.apache.hc.client5.http.ConnectExceptionSupport;
 import org.apache.hc.client5.http.DnsResolver;
 import org.apache.hc.client5.http.SchemePortResolver;
@@ -58,7 +60,6 @@
 import org.apache.hc.core5.http.io.SocketConfig;
 import org.apache.hc.core5.http.protocol.HttpContext;
 import org.apache.hc.core5.io.Closer;
-import org.apache.hc.core5.io.SocketSupport;
 import org.apache.hc.core5.net.NamedEndpoint;
 import org.apache.hc.core5.util.Args;
 import org.apache.hc.core5.util.TimeValue;
@@ -318,13 +319,13 @@ private static void configureSocket(final Socket socket, final SocketConfig sock
             socket.setSoLinger(true, linger);
         }
         if (socketConfig.getTcpKeepIdle() > 0) {
-            SocketSupport.setOption(socket, SocketSupport.TCP_KEEPIDLE, socketConfig.getTcpKeepIdle());
+            Sockets.setOption(socket, ExtendedSocketOptions.TCP_KEEPIDLE, socketConfig.getTcpKeepIdle());
         }
         if (socketConfig.getTcpKeepInterval() > 0) {
-            SocketSupport.setOption(socket, SocketSupport.TCP_KEEPINTERVAL, socketConfig.getTcpKeepInterval());
+            Sockets.setOption(socket, ExtendedSocketOptions.TCP_KEEPINTERVAL, socketConfig.getTcpKeepInterval());
         }
         if (socketConfig.getTcpKeepCount() > 0) {
-            SocketSupport.setOption(socket, SocketSupport.TCP_KEEPCOUNT, socketConfig.getTcpKeepCount());
+            Sockets.setOption(socket, ExtendedSocketOptions.TCP_KEEPCOUNT, socketConfig.getTcpKeepCount());
         }
     }
 

pom.xml

@@ -77,7 +77,7 @@
     <testcontainers.version>1.21.3</testcontainers.version>
     <junixsocket.version>2.10.1</junixsocket.version>
     <api.comparison.version>5.3</api.comparison.version>
-    <hc.animal-sniffer.signature.ignores>javax.net.ssl.SSLEngine,javax.net.ssl.SSLParameters,java.nio.ByteBuffer,java.nio.CharBuffer</hc.animal-sniffer.signature.ignores>
+    <hc.animal-sniffer.signature.ignores>javax.net.ssl.SSLEngine,javax.net.ssl.SSLParameters,java.nio.ByteBuffer,java.nio.CharBuffer,jdk.net.ExtendedSocketOptions,jdk.net.Sockets</hc.animal-sniffer.signature.ignores>
     <commons.compress.version>1.27.1</commons.compress.version>
     <zstd.jni.version>1.5.7-4</zstd.jni.version>
   </properties>