8239355: (dc) Initial value of SO_SNDBUF should allow sending large datagrams (macOS)

Updates DatagramChannel so that the SO_SNDBUF is set to a minimum value of 65527 for IPv6 sockets and 65507 for IPv4 sockets on macOS.

Reviewed-by: alanb, dfuchs

src/java.base/unix/native/libnio/ch/Net.c

@@ -265,6 +265,24 @@ Java_sun_nio_ch_Net_socket0(JNIEnv *env, jclass cl, jboolean preferIPv6,
         }
     }
 #endif
+
+#ifdef __APPLE__
+    /**
+     * Attempt to set SO_SNDBUF to a minimum size to allow sending large datagrams
+     * (net.inet.udp.maxdgram defaults to 9216).
+     */
+    if (type == SOCK_DGRAM) {
+        int size;
+        socklen_t arglen = sizeof(size);
+        if (getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &size, &arglen) == 0) {
+            int minSize = (domain == AF_INET6) ? 65527  : 65507;
+            if (size < minSize) {
+                setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &minSize, sizeof(minSize));
+            }
+        }
+    }
+#endif
+
     return fd;
 }
 

test/jdk/java/net/IPSupport/MinimumPermissions.policy

@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+// Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
 // DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 //
 // This code is free software; you can redistribute it and/or modify it
@@ -24,5 +24,6 @@
 grant codeBase "file:${test.classes}/../../../../test/lib/-" {
     permission java.net.SocketPermission "localhost:0", "listen,resolve";
     permission java.util.PropertyPermission "java.net.preferIPv4Stack", "read";
+    permission java.util.PropertyPermission "java.net.preferIPv6Addresses", "read";
 };
 

test/jdk/java/nio/channels/DatagramChannel/MinSendBufferSize.java

@@ -0,0 +1,166 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8239355
+ * @summary Check that new SO_SNDBUF limit on macOS is adhered to
+ * @library /test/lib
+ * @build jdk.test.lib.net.IPSupport
+ * @requires os.family == "mac"
+ * @run testng/othervm MinSendBufferSize
+ * @run testng/othervm -Djava.net.preferIPv4Stack=true MinSendBufferSize
+ */
+
+import org.testng.annotations.AfterTest;
+import org.testng.annotations.BeforeTest;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+import java.io.IOException;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+import java.net.ProtocolFamily;
+import java.nio.ByteBuffer;
+import java.nio.channels.DatagramChannel;
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.net.StandardSocketOptions.SO_SNDBUF;
+import static jdk.test.lib.net.IPSupport.hasIPv4;
+import static jdk.test.lib.net.IPSupport.hasIPv6;
+import static jdk.test.lib.net.IPSupport.preferIPv4Stack;
+import static java.net.StandardProtocolFamily.INET;
+import static java.net.StandardProtocolFamily.INET6;
+import static org.testng.Assert.assertTrue;
+import static org.testng.Assert.expectThrows;
+
+public class MinSendBufferSize {
+    private int EXPECTED_SNDBUF;
+    private DatagramChannel datagramChannel, datagramChannelIPv4,
+            datagramChannelIPv6;
+
+    private final static int IPV4_SNDBUF = 65507;
+    private final static int IPV6_SNDBUF = 65527;
+    private final static Class<IOException> IOE = IOException.class;
+
+    @BeforeTest
+    public void setUp() throws IOException {
+        datagramChannel = DatagramChannel.open();
+        if (hasIPv4())
+            datagramChannelIPv4 = DatagramChannel.open(INET);
+        if (hasIPv6())
+            datagramChannelIPv6 = DatagramChannel.open(INET6);
+
+        EXPECTED_SNDBUF = hasIPv6() && !preferIPv4Stack()
+                ? IPV6_SNDBUF : IPV4_SNDBUF;
+    }
+
+    private void populateDataProvider(List<Object[]> testcases,
+                                      DatagramChannel datagramChannel,
+                                      int payloadSize,
+                                      ProtocolFamily family) {
+
+        testcases.add(new Object[]{datagramChannel, payloadSize - 1,
+                family, null});
+        testcases.add(new Object[]{datagramChannel, payloadSize,
+                family, null});
+        testcases.add(new Object[]{datagramChannel, payloadSize + 1,
+                family, IOE});
+    }
+
+    @DataProvider(name = "testGetOptionProvider")
+    public Object[][] providerIO() {
+        var testcases = new ArrayList<Object[]>();
+
+        testcases.add(new Object[]{datagramChannel, EXPECTED_SNDBUF});
+        if (hasIPv4())
+            testcases.add(new Object[]{datagramChannelIPv4, IPV4_SNDBUF});
+        if (hasIPv6())
+            testcases.add(new Object[]{datagramChannelIPv6, IPV6_SNDBUF});
+
+        return testcases.toArray(Object[][]::new);
+    }
+
+    @DataProvider(name = "testSendPayloadProvider")
+    public Object[][] providerIO_Payload() {
+        var testcases = new ArrayList<Object[]>();
+
+        if (hasIPv4())
+            populateDataProvider(testcases, datagramChannel,
+                    IPV4_SNDBUF, INET);
+        if (hasIPv6() && !preferIPv4Stack())
+            populateDataProvider(testcases, datagramChannel,
+                    IPV6_SNDBUF, INET6);
+
+        if (hasIPv4())
+            populateDataProvider(testcases, datagramChannelIPv4,
+                    IPV4_SNDBUF, INET);
+        if (hasIPv6())
+            populateDataProvider(testcases, datagramChannelIPv6,
+                    IPV6_SNDBUF, INET6);
+
+        return testcases.toArray(Object[][]::new);
+    }
+
+    @Test(dataProvider = "testGetOptionProvider")
+    public void testGetOption(DatagramChannel channel, int sendBuf)
+            throws IOException {
+
+        assertTrue(channel.getOption(SO_SNDBUF) >= sendBuf);
+    }
+
+    @Test(dataProvider = "testSendPayloadProvider")
+    public void testSend(DatagramChannel channel, int sendBuf,
+                            ProtocolFamily family,
+                            Class<? extends Throwable> exception)
+            throws IOException {
+
+        InetAddress targetAddress;
+        assert family != null;
+        if (family == INET) {
+            targetAddress = InetAddress.getByName("127.0.0.1");
+        } else {
+            targetAddress = InetAddress.getByName("::1");
+        }
+
+        try (var receiver = new DatagramSocket(0, targetAddress)) {
+            var buf = ByteBuffer.allocate(sendBuf);
+            var addr = receiver.getLocalSocketAddress();
+            if (exception != null) {
+                expectThrows(exception, () -> channel.send(buf, addr));
+            } else {
+                channel.send(buf, addr);
+            }
+        }
+    }
+
+    @AfterTest
+    public void tearDown() throws IOException {
+        datagramChannel.close();
+        if (hasIPv4())
+            datagramChannelIPv4.close();
+        if (hasIPv6())
+            datagramChannelIPv6.close();
+    }
+}

test/lib/jdk/test/lib/net/IPSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -29,7 +29,6 @@ import java.io.PrintStream;
 import java.io.UncheckedIOException;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
-import java.net.ServerSocket;
 import java.net.Socket;
 import java.net.SocketException;
 import java.net.UnknownHostException;
@@ -47,6 +46,7 @@ public class IPSupport {
     private static final boolean hasIPv4;
     private static final boolean hasIPv6;
     private static final boolean preferIPv4Stack;
+    private static final boolean preferIPv6Addresses;
 
     static {
         try {
@@ -64,6 +64,8 @@ public class IPSupport {
         }
         preferIPv4Stack = runPrivilegedAction(() -> Boolean.parseBoolean(
             System.getProperty("java.net.preferIPv4Stack")));
+        preferIPv6Addresses = runPrivilegedAction(() -> Boolean.parseBoolean(
+            System.getProperty("java.net.preferIPv6Addresses")));
         if (!preferIPv4Stack && !hasIPv4 && !hasIPv6) {
             throw new AssertionError("IPv4 and IPv6 both not available and java.net.preferIPv4Stack is not true");
         }
@@ -112,6 +114,13 @@ public class IPSupport {
         return preferIPv4Stack;
     }
 
+    /**
+     * Whether or not the "java.net.preferIPv6Addresses" system property is set.
+     */
+    public static final boolean preferIPv6Addresses() {
+        return preferIPv6Addresses;
+    }
+
 
     /**
      * Whether or not the current networking configuration is valid or not.
@@ -152,6 +161,7 @@ public class IPSupport {
         out.println("IPSupport - IPv4: " + hasIPv4());
         out.println("IPSupport - IPv6: " + hasIPv6());
         out.println("preferIPv4Stack: " + preferIPv4Stack());
+        out.println("preferIPv6Addresses: " + preferIPv6Addresses());
     }
 
 }