EpollSocketChannelConfig.getOptions() must not throw if TCP_FASTOPEN_CONNECT is not supported

Motivation:

If a user calls EpollSocketChannelConfig.getOptions() and TCP_FASTOPEN_CONNECT is not supported we throw an exception.

Modifications:

- Just return 0 if ENOPROTOOPT is set.
- Add testcase

Result:

getOptions() works as epxected.

transport-native-epoll/src/main/c/netty_epoll_linuxsocket.c

@@ -256,7 +256,14 @@ static jint netty_epoll_linuxsocket_isTcpQuickAck(JNIEnv* env, jclass clazz, jin
 
 static jint netty_epoll_linuxsocket_isTcpFastOpenConnect(JNIEnv* env, jclass clazz, jint fd) {
     int optval;
-    if (netty_unix_socket_getOption(env, fd, IPPROTO_TCP, TCP_FASTOPEN_CONNECT, &optval, sizeof(optval)) == -1) {
+    int optlen = sizeof(optval);
+    // We call getsockopt directly so we can handle ENOPROTOOPT by ourself.
+    if (getsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN_CONNECT, &optval, &optlen) == -1) {
+        if (errno == ENOPROTOOPT) {
+            // Not supported by the system, so just return 0.
+            return 0;
+        }
+        netty_unix_socket_getOptionHandleError(env, errno);
         return -1;
     }
     return optval;

transport-native-epoll/src/test/java/io/netty/channel/epoll/EpollServerSocketChannelConfigTest.java

@@ -17,12 +17,14 @@ package io.netty.channel.epoll;
 
 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.ChannelInboundHandlerAdapter;
+import io.netty.channel.ChannelOption;
 import io.netty.channel.EventLoopGroup;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
 import java.net.InetSocketAddress;
+import java.util.Map;
 
 import static org.junit.Assert.*;
 
@@ -75,4 +77,10 @@ public class EpollServerSocketChannelConfigTest {
         ch.config().setFreeBind(true);
         assertTrue(ch.config().isFreeBind());
     }
+
+    @Test
+    public void getGetOptions() {
+        Map<ChannelOption<?>, Object> map = ch.config().getOptions();
+        assertFalse(map.isEmpty());
+    }
 }

transport-native-epoll/src/test/java/io/netty/channel/epoll/EpollSocketChannelConfigTest.java

@@ -20,10 +20,12 @@ import static org.junit.Assume.*;
 import io.netty.bootstrap.Bootstrap;
 import io.netty.channel.ChannelException;
 import io.netty.channel.ChannelInboundHandlerAdapter;
+import io.netty.channel.ChannelOption;
 import io.netty.channel.EventLoopGroup;
 
 import java.net.InetSocketAddress;
 import java.nio.channels.ClosedChannelException;
+import java.util.Map;
 import java.util.Random;
 
 import org.junit.After;
@@ -153,4 +155,10 @@ public class EpollSocketChannelConfigTest {
             assertTrue(e.getCause() instanceof ClosedChannelException);
         }
     }
+
+    @Test
+    public void getGetOptions() {
+        Map<ChannelOption<?>, Object> map = ch.config().getOptions();
+        assertFalse(map.isEmpty());
+    }
 }

transport-native-unix-common/src/main/c/netty_unix_socket.c

@@ -324,7 +324,7 @@ static jobject _recvFrom(JNIEnv* env, jint fd, void* buffer, jint pos, jint limi
     return createDatagramSocketAddress(env, &addr, res);
 }
 
-static void netty_unix_socket_getOptionHandleError(JNIEnv* env, int err) {
+void netty_unix_socket_getOptionHandleError(JNIEnv* env, int err) {
     netty_unix_socket_optionHandleError(env, err, "getsockopt() failed: ");
 }
 

transport-native-unix-common/src/main/c/netty_unix_socket.h

@@ -24,6 +24,10 @@ int netty_unix_socket_initSockaddr(JNIEnv* env, jbyteArray address, jint scopeId
 int netty_unix_socket_getOption(JNIEnv* env, jint fd, int level, int optname, void* optval, socklen_t optlen);
 int netty_unix_socket_setOption(JNIEnv* env, jint fd, int level, int optname, const void* optval, socklen_t len);
 
+// These method is sometimes needed if you want to special handle some errno value before throwing an exception.
+void netty_unix_socket_getOptionHandleError(JNIEnv* env, int err);
+
+
 // JNI initialization hooks. Users of this file are responsible for calling these in the JNI_OnLoad and JNI_OnUnload methods.
 jint netty_unix_socket_JNI_OnLoad(JNIEnv* env, const char* packagePrefix);
 void netty_unix_socket_JNI_OnUnLoad(JNIEnv* env);