4.x - Custom DNS resolvers for Nima (#4876)

* Custom DNS resolving

Signed-off-by: David Kral <david.k.kral@oracle.com>

nima/http2/webclient/src/main/java/io/helidon/nima/http2/webclient/ClientRequestImpl.java

@@ -36,6 +36,7 @@
 import io.helidon.nima.http2.Http2Headers;
 import io.helidon.nima.webclient.ClientConnection;
 import io.helidon.nima.webclient.ClientRequest;
+import io.helidon.nima.webclient.ConnectionKey;
 import io.helidon.nima.webclient.UriHelper;
 
 class ClientRequestImpl implements Http2ClientRequest {
@@ -217,7 +218,12 @@ private Http2Headers prepareHeaders(WritableHeaders<?> headers) {
 
     private Http2ClientStream reserveStream() {
         if (explicitConnection == null) {
-            ConnectionKey connectionKey = new ConnectionKey(uri.scheme(), uri.authority(), uri.host(), uri.port(), tls);
+            ConnectionKey connectionKey = new ConnectionKey(uri.scheme(),
+                                                            uri.host(),
+                                                            uri.port(),
+                                                            tls,
+                                                            client.dnsResolver(),
+                                                            client.dnsAddressLookup());
 
             // this statement locks all threads - must not do anything complicated (just create a new instance)
             return CHANNEL_CACHE.computeIfAbsent(connectionKey,

nima/http2/webclient/src/main/java/io/helidon/nima/http2/webclient/Http2ClientConnection.java

@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.UncheckedIOException;
+import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.security.cert.Certificate;
@@ -37,6 +38,8 @@
 import io.helidon.common.socket.SocketWriter;
 import io.helidon.common.socket.TlsSocket;
 import io.helidon.nima.http2.Http2ConnectionWriter;
+import io.helidon.nima.webclient.ConnectionKey;
+import io.helidon.nima.webclient.spi.DnsResolver;
 
 import static java.lang.System.Logger.Level.DEBUG;
 import static java.lang.System.Logger.Level.TRACE;
@@ -109,9 +112,14 @@ private void doConnect() throws IOException {
         socket = sslSocket == null ? new Socket() : sslSocket;
 
         socketOptions.configureSocket(socket);
-        socket.connect(new InetSocketAddress(connectionKey.host(),
-                                             connectionKey.port()),
-                       (int) socketOptions.connectTimeout().toMillis());
+        DnsResolver dnsResolver = connectionKey.dnsResolver();
+        if (dnsResolver.useDefaultJavaResolver()) {
+            socket.connect(new InetSocketAddress(connectionKey.host(), connectionKey.port()),
+                           (int) socketOptions.connectTimeout().toMillis());
+        } else {
+            InetAddress address = dnsResolver.resolveAddress(connectionKey.host(), connectionKey.dnsAddressLookup());
+            socket.connect(new InetSocketAddress(address, connectionKey.port()), (int) socketOptions.connectTimeout().toMillis());
+        }
         channelId = "0x" + HexFormat.of().toHexDigits(System.identityHashCode(socket));
 
         helidonSocket = sslSocket == null

nima/http2/webclient/src/main/java/io/helidon/nima/http2/webclient/Http2ClientConnectionHandler.java

@@ -23,6 +23,7 @@
 import java.util.concurrent.atomic.AtomicReference;
 
 import io.helidon.common.socket.SocketOptions;
+import io.helidon.nima.webclient.ConnectionKey;
 
 // a representation of a single remote endpoint
 // this may use one or more connections (depending on parallel streams)

nima/webclient/webclient/src/main/java/io/helidon/nima/webclient/ConnectionKey.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2022 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.nima.webclient;
+
+import io.helidon.nima.common.tls.Tls;
+import io.helidon.nima.webclient.spi.DnsResolver;
+
+/**
+ * Connection key instance contains all needed connection related information.
+ *
+ * @param scheme uri address scheme
+ * @param host uri address host
+ * @param port uri address port
+ * @param tls TLS to be used in connection
+ * @param dnsResolver DNS resolver to be used
+ * @param dnsAddressLookup DNS address lookup strategy
+ */
+public record ConnectionKey(String scheme,
+                            String host,
+                            int port,
+                            Tls tls,
+                            DnsResolver dnsResolver,
+                            DnsAddressLookup dnsAddressLookup) { }

nima/webclient/webclient/src/main/java/io/helidon/nima/webclient/DefaultDnsAddressLookupFinder.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2022 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.nima.webclient;
+
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.util.Enumeration;
+
+import io.helidon.common.LazyValue;
+
+/**
+ * Heavily inspired by Netty.
+ */
+final class DefaultDnsAddressLookupFinder {
+
+    private static final System.Logger LOGGER = System.getLogger(DefaultDnsAddressLookupFinder.class.getName());
+
+    /**
+     * {@code true} if IPv4 should be used even if the system supports both IPv4 and IPv6.
+     */
+    private static final LazyValue<Boolean> IPV4_PREFERRED = LazyValue.create(() -> {
+        return Boolean.getBoolean("java.net.preferIPv4Stack");
+    });
+
+    /**
+     * {@code true} if an IPv6 address should be preferred when a host has both an IPv4 address and an IPv6 address.
+     */
+    private static final LazyValue<Boolean> IPV6_PREFERRED = LazyValue.create(() -> {
+        return Boolean.getBoolean("java.net.preferIPv6Addresses");
+    });
+
+    private static final LazyValue<DnsAddressLookup> DEFAULT_IP_VERSION = LazyValue.create(() -> {
+        if (IPV4_PREFERRED.get() || !anyInterfaceSupportsIpV6()) {
+            return DnsAddressLookup.IPV4;
+        } else {
+            if (IPV6_PREFERRED.get()) {
+                return DnsAddressLookup.IPV6_PREFERRED;
+            } else {
+                return DnsAddressLookup.IPV4_PREFERRED;
+            }
+        }
+    });
+
+    private DefaultDnsAddressLookupFinder() {
+        throw new IllegalStateException("This class should not be instantiated");
+    }
+
+    static DnsAddressLookup defaultDnsAddressLookup() {
+        return DEFAULT_IP_VERSION.get();
+    }
+
+    /**
+     * Returns {@code true} if any {@link NetworkInterface} supports {@code IPv6}, {@code false} otherwise.
+     */
+    private static boolean anyInterfaceSupportsIpV6() {
+        try {
+            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
+            while (interfaces.hasMoreElements()) {
+                NetworkInterface networkInterface = interfaces.nextElement();
+                Enumeration<InetAddress> addresses = networkInterface.getInetAddresses();
+                while (addresses.hasMoreElements()) {
+                    InetAddress inetAddress = addresses.nextElement();
+                    if (inetAddress instanceof Inet6Address
+                            && !inetAddress.isAnyLocalAddress()
+                            && !inetAddress.isLoopbackAddress()
+                            && !inetAddress.isLinkLocalAddress()) {
+                        return true;
+                    }
+                }
+            }
+        } catch (SocketException ignore) {
+            if (LOGGER.isLoggable(System.Logger.Level.INFO)) {
+                LOGGER.log(System.Logger.Level.INFO,
+                           "Unable to detect if any interface supports IPv6, assuming IPv4-only",
+                           ignore);
+            }
+        }
+        return false;
+    }
+
+}

nima/webclient/webclient/src/main/java/io/helidon/nima/webclient/DefaultDnsResolver.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2022 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.nima.webclient;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.HashMap;
+import java.util.Map;
+
+import io.helidon.nima.webclient.spi.DnsResolver;
+
+final class DefaultDnsResolver implements DnsResolver {
+
+    private final Map<String, InetAddress> hostnameAddresses = new HashMap<>();
+
+    @Override
+    public InetAddress resolveAddress(String hostname, DnsAddressLookup dnsAddressLookup) {
+        return hostnameAddresses.computeIfAbsent(hostname, host -> {
+            try {
+                InetAddress[] processed = dnsAddressLookup.filter(InetAddress.getAllByName(hostname));
+                if (processed.length == 0) {
+                    throw new RuntimeUnknownHostException("No IP version " + dnsAddressLookup.name() + " found for host " + host);
+                }
+                return processed[0];
+            } catch (UnknownHostException e) {
+                throw new RuntimeUnknownHostException(e);
+            }
+        });
+    }
+
+}

nima/webclient/webclient/src/main/java/io/helidon/nima/webclient/DefaultDnsResolverProvider.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2022 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.nima.webclient;
+
+import io.helidon.common.Weight;
+import io.helidon.common.Weighted;
+import io.helidon.nima.webclient.spi.DnsResolver;
+import io.helidon.nima.webclient.spi.DnsResolverProvider;
+
+/**
+ * Provider of the {@link DefaultDnsResolver} instance.
+ */
+@Weight(Weighted.DEFAULT_WEIGHT)
+public class DefaultDnsResolverProvider implements DnsResolverProvider {
+
+    /**
+     * Create new instance of the {@link DefaultDnsResolverProvider}.
+     * This should be used only for purposes of SPI.
+     */
+    public DefaultDnsResolverProvider() {
+    }
+
+    @Override
+    public String resolverName() {
+        return "default";
+    }
+
+    @Override
+    public DnsResolver createDnsResolver() {
+        return new DefaultDnsResolver();
+    }
+}