/*
 * Copyright (c) 2011-2018 Contributors to the Eclipse Foundation
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 * which is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 */

package io.vertx.core.impl;

import io.netty.resolver.AddressResolverGroup;
import io.vertx.core.AsyncResult;
import io.vertx.core.Future;
import io.vertx.core.Handler;
import io.vertx.core.Vertx;
import io.vertx.core.dns.AddressResolverOptions;
import io.vertx.core.impl.launcher.commands.ExecUtils;
import io.vertx.core.logging.Logger;
import io.vertx.core.logging.LoggerFactory;
import io.vertx.core.spi.resolver.ResolverProvider;

import java.io.File;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.file.Files;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

Author:Julien Viet
/** * @author <a href="mailto:julien@julienviet.com">Julien Viet</a> */
public class AddressResolver { private static final Logger log = LoggerFactory.getLogger(AddressResolver.class); private static Pattern resolvOption(String regex) { return Pattern.compile("^[ \\t\\f]*options[^\n]+" + regex + "(?=$|\\s)", Pattern.MULTILINE); } private static final Pattern NDOTS_OPTIONS_PATTERN = resolvOption("ndots:[ \\t\\f]*(\\d)+"); private static final Pattern ROTATE_OPTIONS_PATTERN = resolvOption("rotate"); public static final int DEFAULT_NDOTS_RESOLV_OPTION; public static final boolean DEFAULT_ROTATE_RESOLV_OPTION; static { int ndots = 1; boolean rotate = false; if (ExecUtils.isLinux()) { File f = new File("/etc/resolv.conf"); try { if (f.exists() && f.isFile()) { String conf = new String(Files.readAllBytes(f.toPath())); int ndotsOption = parseNdotsOptionFromResolvConf(conf); if (ndotsOption != -1) { ndots = ndotsOption; } rotate = parseRotateOptionFromResolvConf(conf); } } catch (Throwable t) { log.debug("Failed to load options from /etc/resolv/.conf", t); } } DEFAULT_NDOTS_RESOLV_OPTION = ndots; DEFAULT_ROTATE_RESOLV_OPTION = rotate; } private final Vertx vertx; private final AddressResolverGroup<InetSocketAddress> resolverGroup; private final ResolverProvider provider; public AddressResolver(Vertx vertx, AddressResolverOptions options) { this.provider = ResolverProvider.factory(vertx, options); this.resolverGroup = provider.resolver(options); this.vertx = vertx; } public void resolveHostname(String hostname, Handler<AsyncResult<InetAddress>> resultHandler) { ContextInternal callback = (ContextInternal) vertx.getOrCreateContext(); io.netty.resolver.AddressResolver<InetSocketAddress> resolver = resolverGroup.getResolver(callback.nettyEventLoop()); io.netty.util.concurrent.Future<InetSocketAddress> fut = resolver.resolve(InetSocketAddress.createUnresolved(hostname, 0)); fut.addListener(a -> { callback.runOnContext(v -> { if (a.isSuccess()) { InetSocketAddress address = fut.getNow(); resultHandler.handle(Future.succeededFuture(address.getAddress())); } else { resultHandler.handle(Future.failedFuture(a.cause())); } }); }); } AddressResolverGroup<InetSocketAddress> nettyAddressResolverGroup() { return resolverGroup; } public void close(Handler<Void> doneHandler) { provider.close(doneHandler); } public static int parseNdotsOptionFromResolvConf(String s) { int ndots = -1; Matcher matcher = NDOTS_OPTIONS_PATTERN.matcher(s); while (matcher.find()) { ndots = Integer.parseInt(matcher.group(1)); } return ndots; } public static boolean parseRotateOptionFromResolvConf(String s) { Matcher matcher = ROTATE_OPTIONS_PATTERN.matcher(s); return matcher.find(); } }