Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 org.apache.hadoop.net; import java.io.EOFException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.lang.reflect.Constructor; import java.net.BindException; import java.net.InetAddress; import java.net.InetSocketAddress; import java.net.NetworkInterface; import java.net.NoRouteToHostException; import java.net.ServerSocket; import java.net.Socket; import java.net.SocketAddress; import java.net.SocketException; import java.net.SocketTimeoutException; import java.net.URI; import java.net.URISyntaxException; import java.net.UnknownHostException; import java.net.ConnectException; import java.nio.channels.SocketChannel; import java.util.Map.Entry; import java.util.regex.Pattern; import java.util.*; import java.util.concurrent.ConcurrentHashMap; import javax.net.SocketFactory; import org.apache.commons.net.util.SubnetUtils; import org.apache.commons.net.util.SubnetUtils.SubnetInfo; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.classification.InterfaceStability; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.CommonConfigurationKeysPublic; import org.apache.hadoop.ipc.Server; import org.apache.hadoop.ipc.VersionedProtocol; import org.apache.hadoop.security.SecurityUtil; import org.apache.hadoop.util.ReflectionUtils; import com.google.common.base.Preconditions; import org.slf4j.Logger; import org.slf4j.LoggerFactory; @InterfaceAudience.LimitedPrivate({ "HDFS", "MapReduce" }) @InterfaceStability.Unstable public class NetUtils { private static final Logger LOG = LoggerFactory.getLogger(NetUtils.class); private static Map<String, String> hostToResolved = new HashMap<String, String>(); /** text to point users elsewhere: {@value} */ private static final String FOR_MORE_DETAILS_SEE = " For more details see: "; /** text included in wrapped exceptions if the host is null: {@value} */ public static final String UNKNOWN_HOST = "(unknown)"; /** Base URL of the Hadoop Wiki: {@value} */ public static final String HADOOP_WIKI = "http://wiki.apache.org/hadoop/"; /** * Get the socket factory for the given class according to its * configuration parameter * <tt>hadoop.rpc.socket.factory.class.<ClassName></tt>. When no * such parameter exists then fall back on the default socket factory as * configured by <tt>hadoop.rpc.socket.factory.class.default</tt>. If * this default socket factory is not configured, then fall back on the JVM * default socket factory. * * @param conf the configuration * @param clazz the class (usually a {@link VersionedProtocol}) * @return a socket factory */ public static SocketFactory getSocketFactory(Configuration conf, Class<?> clazz) { SocketFactory factory = null; String propValue = conf.get("hadoop.rpc.socket.factory.class." + clazz.getSimpleName()); if ((propValue != null) && (propValue.length() > 0)) factory = getSocketFactoryFromProperty(conf, propValue); if (factory == null) factory = getDefaultSocketFactory(conf); return factory; } /** * Get the default socket factory as specified by the configuration * parameter <tt>hadoop.rpc.socket.factory.default</tt> * * @param conf the configuration * @return the default socket factory as specified in the configuration or * the JVM default socket factory if the configuration does not * contain a default socket factory property. */ public static SocketFactory getDefaultSocketFactory(Configuration conf) { String propValue = conf.get(CommonConfigurationKeysPublic.HADOOP_RPC_SOCKET_FACTORY_CLASS_DEFAULT_KEY, CommonConfigurationKeysPublic.HADOOP_RPC_SOCKET_FACTORY_CLASS_DEFAULT_DEFAULT); if ((propValue == null) || (propValue.length() == 0)) return SocketFactory.getDefault(); return getSocketFactoryFromProperty(conf, propValue); } /** * Get the socket factory corresponding to the given proxy URI. If the * given proxy URI corresponds to an absence of configuration parameter, * returns null. If the URI is malformed raises an exception. * * @param propValue the property which is the class name of the * SocketFactory to instantiate; assumed non null and non empty. * @return a socket factory as defined in the property value. */ public static SocketFactory getSocketFactoryFromProperty(Configuration conf, String propValue) { try { Class<?> theClass = conf.getClassByName(propValue); return (SocketFactory) ReflectionUtils.newInstance(theClass, conf); } catch (ClassNotFoundException cnfe) { throw new RuntimeException("Socket Factory class not found: " + cnfe); } } /** * Util method to build socket addr from either: * <host>:<port> * <fs>://<host>:<port>/<path> */ public static InetSocketAddress createSocketAddr(String target) { return createSocketAddr(target, -1); } /** * Util method to build socket addr from either: * <host> * <host>:<port> * <fs>://<host>:<port>/<path> */ public static InetSocketAddress createSocketAddr(String target, int defaultPort) { return createSocketAddr(target, defaultPort, null); } /** * Create an InetSocketAddress from the given target string and * default port. If the string cannot be parsed correctly, the * <code>configName</code> parameter is used as part of the * exception message, allowing the user to better diagnose * the misconfiguration. * * @param target a string of either "host" or "host:port" * @param defaultPort the default port if <code>target</code> does not * include a port number * @param configName the name of the configuration from which * <code>target</code> was loaded. This is used in the * exception message in the case that parsing fails. */ public static InetSocketAddress createSocketAddr(String target, int defaultPort, String configName) { String helpText = ""; if (configName != null) { helpText = " (configuration property '" + configName + "')"; } if (target == null) { throw new IllegalArgumentException("Target address cannot be null." + helpText); } target = target.trim(); boolean hasScheme = target.contains("://"); URI uri = null; try { uri = hasScheme ? URI.create(target) : URI.create("dummyscheme://" + target); } catch (IllegalArgumentException e) { throw new IllegalArgumentException( "Does not contain a valid host:port authority: " + target + helpText); } String host = uri.getHost(); int port = uri.getPort(); if (port == -1) { port = defaultPort; } String path = uri.getPath(); if ((host == null) || (port < 0) || (!hasScheme && path != null && !path.isEmpty())) { throw new IllegalArgumentException( "Does not contain a valid host:port authority: " + target + helpText); } return createSocketAddrForHost(host, port); } /** * Create a socket address with the given host and port. The hostname * might be replaced with another host that was set via * {@link #addStaticResolution(String, String)}. The value of * hadoop.security.token.service.use_ip will determine whether the * standard java host resolver is used, or if the fully qualified resolver * is used. * @param host the hostname or IP use to instantiate the object * @param port the port number * @return InetSocketAddress */ public static InetSocketAddress createSocketAddrForHost(String host, int port) { String staticHost = getStaticResolution(host); String resolveHost = (staticHost != null) ? staticHost : host; InetSocketAddress addr; try { InetAddress iaddr = SecurityUtil.getByName(resolveHost); // if there is a static entry for the host, make the returned // address look like the original given host if (staticHost != null) { iaddr = InetAddress.getByAddress(host, iaddr.getAddress()); } addr = new InetSocketAddress(iaddr, port); } catch (UnknownHostException e) { addr = InetSocketAddress.createUnresolved(host, port); } return addr; } /** * Resolve the uri's hostname and add the default port if not in the uri * @param uri to resolve * @param defaultPort if none is given * @return URI */ public static URI getCanonicalUri(URI uri, int defaultPort) { // skip if there is no authority, ie. "file" scheme or relative uri String host = uri.getHost(); if (host == null) { return uri; } String fqHost = canonicalizeHost(host); int port = uri.getPort(); // short out if already canonical with a port if (host.equals(fqHost) && port != -1) { return uri; } // reconstruct the uri with the canonical host and port try { uri = new URI(uri.getScheme(), uri.getUserInfo(), fqHost, (port == -1) ? defaultPort : port, uri.getPath(), uri.getQuery(), uri.getFragment()); } catch (URISyntaxException e) { throw new IllegalArgumentException(e); } return uri; } // cache the canonicalized hostnames; the cache currently isn't expired, // but the canonicals will only change if the host's resolver configuration // changes private static final ConcurrentHashMap<String, String> canonicalizedHostCache = new ConcurrentHashMap<String, String>(); private static String canonicalizeHost(String host) { // check if the host has already been canonicalized String fqHost = canonicalizedHostCache.get(host); if (fqHost == null) { try { fqHost = SecurityUtil.getByName(host).getHostName(); // slight race condition, but won't hurt canonicalizedHostCache.putIfAbsent(host, fqHost); } catch (UnknownHostException e) { fqHost = host; } } return fqHost; } /** * Adds a static resolution for host. This can be used for setting up * hostnames with names that are fake to point to a well known host. For e.g. * in some testcases we require to have daemons with different hostnames * running on the same machine. In order to create connections to these * daemons, one can set up mappings from those hostnames to "localhost". * {@link NetUtils#getStaticResolution(String)} can be used to query for * the actual hostname. * @param host * @param resolvedName */ public static void addStaticResolution(String host, String resolvedName) { synchronized (hostToResolved) { hostToResolved.put(host, resolvedName); } } /** * Retrieves the resolved name for the passed host. The resolved name must * have been set earlier using * {@link NetUtils#addStaticResolution(String, String)} * @param host * @return the resolution */ public static String getStaticResolution(String host) { synchronized (hostToResolved) { return hostToResolved.get(host); } } /** * This is used to get all the resolutions that were added using * {@link NetUtils#addStaticResolution(String, String)}. The return * value is a List each element of which contains an array of String * of the form String[0]=hostname, String[1]=resolved-hostname * @return the list of resolutions */ public static List<String[]> getAllStaticResolutions() { synchronized (hostToResolved) { Set<Entry<String, String>> entries = hostToResolved.entrySet(); if (entries.size() == 0) { return null; } List<String[]> l = new ArrayList<String[]>(entries.size()); for (Entry<String, String> e : entries) { l.add(new String[] { e.getKey(), e.getValue() }); } return l; } } /** * Returns InetSocketAddress that a client can use to * connect to the server. Server.getListenerAddress() is not correct when * the server binds to "0.0.0.0". This returns "hostname:port" of the server, * or "127.0.0.1:port" when the getListenerAddress() returns "0.0.0.0:port". * * @param server * @return socket address that a client can use to connect to the server. */ public static InetSocketAddress getConnectAddress(Server server) { return getConnectAddress(server.getListenerAddress()); } /** * Returns an InetSocketAddress that a client can use to connect to the * given listening address. * * @param addr of a listener * @return socket address that a client can use to connect to the server. */ public static InetSocketAddress getConnectAddress(InetSocketAddress addr) { if (!addr.isUnresolved() && addr.getAddress().isAnyLocalAddress()) { try { addr = new InetSocketAddress(InetAddress.getLocalHost(), addr.getPort()); } catch (UnknownHostException uhe) { // shouldn't get here unless the host doesn't have a loopback iface addr = createSocketAddrForHost("127.0.0.1", addr.getPort()); } } return addr; } /** * Same as <code>getInputStream(socket, socket.getSoTimeout()).</code> * <br><br> * * @see #getInputStream(Socket, long) */ public static SocketInputWrapper getInputStream(Socket socket) throws IOException { return getInputStream(socket, socket.getSoTimeout()); } /** * Return a {@link SocketInputWrapper} for the socket and set the given * timeout. If the socket does not have an associated channel, then its socket * timeout will be set to the specified value. Otherwise, a * {@link SocketInputStream} will be created which reads with the configured * timeout. * * Any socket created using socket factories returned by {@link #NetUtils}, * must use this interface instead of {@link Socket#getInputStream()}. * * In general, this should be called only once on each socket: see the note * in {@link SocketInputWrapper#setTimeout(long)} for more information. * * @see Socket#getChannel() * * @param socket * @param timeout timeout in milliseconds. zero for waiting as * long as necessary. * @return SocketInputWrapper for reading from the socket. * @throws IOException */ public static SocketInputWrapper getInputStream(Socket socket, long timeout) throws IOException { InputStream stm = (socket.getChannel() == null) ? socket.getInputStream() : new SocketInputStream(socket); SocketInputWrapper w = new SocketInputWrapper(socket, stm); w.setTimeout(timeout); return w; } /** * Same as getOutputStream(socket, 0). Timeout of zero implies write will * wait until data is available.<br><br> * * From documentation for {@link #getOutputStream(Socket, long)} : <br> * Returns OutputStream for the socket. If the socket has an associated * SocketChannel then it returns a * {@link SocketOutputStream} with the given timeout. If the socket does not * have a channel, {@link Socket#getOutputStream()} is returned. In the later * case, the timeout argument is ignored and the write will wait until * data is available.<br><br> * * Any socket created using socket factories returned by {@link NetUtils}, * must use this interface instead of {@link Socket#getOutputStream()}. * * @see #getOutputStream(Socket, long) * * @param socket * @return OutputStream for writing to the socket. * @throws IOException */ public static OutputStream getOutputStream(Socket socket) throws IOException { return getOutputStream(socket, 0); } /** * Returns OutputStream for the socket. If the socket has an associated * SocketChannel then it returns a * {@link SocketOutputStream} with the given timeout. If the socket does not * have a channel, {@link Socket#getOutputStream()} is returned. In the later * case, the timeout argument is ignored and the write will wait until * data is available.<br><br> * * Any socket created using socket factories returned by {@link NetUtils}, * must use this interface instead of {@link Socket#getOutputStream()}. * * @see Socket#getChannel() * * @param socket * @param timeout timeout in milliseconds. This may not always apply. zero * for waiting as long as necessary. * @return OutputStream for writing to the socket. * @throws IOException */ public static OutputStream getOutputStream(Socket socket, long timeout) throws IOException { return (socket.getChannel() == null) ? socket.getOutputStream() : new SocketOutputStream(socket, timeout); } /** * This is a drop-in replacement for * {@link Socket#connect(SocketAddress, int)}. * In the case of normal sockets that don't have associated channels, this * just invokes <code>socket.connect(endpoint, timeout)</code>. If * <code>socket.getChannel()</code> returns a non-null channel, * connect is implemented using Hadoop's selectors. This is done mainly * to avoid Sun's connect implementation from creating thread-local * selectors, since Hadoop does not have control on when these are closed * and could end up taking all the available file descriptors. * * @see java.net.Socket#connect(java.net.SocketAddress, int) * * @param socket * @param address the remote address * @param timeout timeout in milliseconds */ public static void connect(Socket socket, SocketAddress address, int timeout) throws IOException { connect(socket, address, null, timeout); } /** * Like {@link NetUtils#connect(Socket, SocketAddress, int)} but * also takes a local address and port to bind the socket to. * * @param socket * @param endpoint the remote address * @param localAddr the local address to bind the socket to * @param timeout timeout in milliseconds */ public static void connect(Socket socket, SocketAddress endpoint, SocketAddress localAddr, int timeout) throws IOException { if (socket == null || endpoint == null || timeout < 0) { throw new IllegalArgumentException("Illegal argument for connect()"); } SocketChannel ch = socket.getChannel(); if (localAddr != null) { Class localClass = localAddr.getClass(); Class remoteClass = endpoint.getClass(); Preconditions.checkArgument(localClass.equals(remoteClass), "Local address %s must be of same family as remote address %s.", localAddr, endpoint); socket.bind(localAddr); } try { if (ch == null) { // let the default implementation handle it. socket.connect(endpoint, timeout); } else { SocketIOWithTimeout.connect(ch, endpoint, timeout); } } catch (SocketTimeoutException ste) { throw new ConnectTimeoutException(ste.getMessage()); } // There is a very rare case allowed by the TCP specification, such that // if we are trying to connect to an endpoint on the local machine, // and we end up choosing an ephemeral port equal to the destination port, // we will actually end up getting connected to ourself (ie any data we // send just comes right back). This is only possible if the target // daemon is down, so we'll treat it like connection refused. if (socket.getLocalPort() == socket.getPort() && socket.getLocalAddress().equals(socket.getInetAddress())) { LOG.info("Detected a loopback TCP socket, disconnecting it"); socket.close(); throw new ConnectException("Localhost targeted connection resulted in a loopback. " + "No daemon is listening on the target port."); } } /** * Given a string representation of a host, return its ip address * in textual presentation. * * @param name a string representation of a host: * either a textual representation its IP address or its host name * @return its IP address in the string format */ public static String normalizeHostName(String name) { try { return InetAddress.getByName(name).getHostAddress(); } catch (UnknownHostException e) { return name; } } /** * Given a collection of string representation of hosts, return a list of * corresponding IP addresses in the textual representation. * * @param names a collection of string representations of hosts * @return a list of corresponding IP addresses in the string format * @see #normalizeHostName(String) */ public static List<String> normalizeHostNames(Collection<String> names) { List<String> hostNames = new ArrayList<String>(names.size()); for (String name : names) { hostNames.add(normalizeHostName(name)); } return hostNames; } /** * Performs a sanity check on the list of hostnames/IPs to verify they at least * appear to be valid. * @param names - List of hostnames/IPs * @throws UnknownHostException */ public static void verifyHostnames(String[] names) throws UnknownHostException { for (String name : names) { if (name == null) { throw new UnknownHostException("null hostname found"); } // The first check supports URL formats (e.g. hdfs://, etc.). // java.net.URI requires a schema, so we add a dummy one if it doesn't // have one already. URI uri = null; try { uri = new URI(name); if (uri.getHost() == null) { uri = new URI("http://" + name); } } catch (URISyntaxException e) { uri = null; } if (uri == null || uri.getHost() == null) { throw new UnknownHostException(name + " is not a valid Inet address"); } } } private static final Pattern ipPortPattern = // Pattern for matching ip[:port] Pattern.compile("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}(:\\d+)?"); /** * Attempt to obtain the host name of the given string which contains * an IP address and an optional port. * * @param ipPort string of form ip[:port] * @return Host name or null if the name can not be determined */ public static String getHostNameOfIP(String ipPort) { if (null == ipPort || !ipPortPattern.matcher(ipPort).matches()) { return null; } try { int colonIdx = ipPort.indexOf(':'); String ip = (-1 == colonIdx) ? ipPort : ipPort.substring(0, ipPort.indexOf(':')); return InetAddress.getByName(ip).getHostName(); } catch (UnknownHostException e) { return null; } } /** * Return hostname without throwing exception. * The returned hostname String format is "hostname". * @return hostname */ public static String getLocalHostname() { try { return InetAddress.getLocalHost().getHostName(); } catch (UnknownHostException uhe) { return "" + uhe; } } /** * Return hostname without throwing exception. * The returned hostname String format is "hostname/ip address". * @return hostname */ public static String getHostname() { try { return "" + InetAddress.getLocalHost(); } catch (UnknownHostException uhe) { return "" + uhe; } } /** * Compose a "host:port" string from the address. */ public static String getHostPortString(InetSocketAddress addr) { return addr.getHostName() + ":" + addr.getPort(); } /** * Checks if {@code host} is a local host name and return {@link InetAddress} * corresponding to that address. * * @param host the specified host * @return a valid local {@link InetAddress} or null * @throws SocketException if an I/O error occurs */ public static InetAddress getLocalInetAddress(String host) throws SocketException { if (host == null) { return null; } InetAddress addr = null; try { addr = SecurityUtil.getByName(host); if (NetworkInterface.getByInetAddress(addr) == null) { addr = null; // Not a local address } } catch (UnknownHostException ignore) { } return addr; } /** * Given an InetAddress, checks to see if the address is a local address, by * comparing the address with all the interfaces on the node. * @param addr address to check if it is local node's address * @return true if the address corresponds to the local node */ public static boolean isLocalAddress(InetAddress addr) { // Check if the address is any local or loop back boolean local = addr.isAnyLocalAddress() || addr.isLoopbackAddress(); // Check if the address is defined on any interface if (!local) { try { local = NetworkInterface.getByInetAddress(addr) != null; } catch (SocketException e) { local = false; } } return local; } /** * Take an IOException , the local host port and remote host port details and * return an IOException with the input exception as the cause and also * include the host details. The new exception provides the stack trace of the * place where the exception is thrown and some extra diagnostics information. * If the exception is of type BindException, ConnectException, * UnknownHostException, SocketTimeoutException or has a String constructor, * return a new one of the same type; Otherwise return an IOException. * * @param destHost target host (nullable) * @param destPort target port * @param localHost local host (nullable) * @param localPort local port * @param exception the caught exception. * @return an exception to throw */ public static IOException wrapException(final String destHost, final int destPort, final String localHost, final int localPort, final IOException exception) { try { if (exception instanceof BindException) { return wrapWithMessage(exception, "Problem binding to [" + localHost + ":" + localPort + "] " + exception + ";" + see("BindException")); } else if (exception instanceof ConnectException) { // Check if client was trying to connect to an unspecified IPv4 address // (0.0.0.0) or IPv6 address(0:0:0:0:0:0:0:0 or ::) if ((destHost != null && (destHost.equals("0.0.0.0") || destHost.equals("0:0:0:0:0:0:0:0") || destHost.equals("::"))) || destPort == 0) { return wrapWithMessage(exception, "Your endpoint configuration" + " is wrong;" + see("UnsetHostnameOrPort")); } else { // connection refused; include the host:port in the error return wrapWithMessage(exception, "Call From " + localHost + " to " + destHost + ":" + destPort + " failed on connection exception: " + exception + ";" + see("ConnectionRefused")); } } else if (exception instanceof UnknownHostException) { return wrapWithMessage(exception, "Invalid host name: " + getHostDetailsAsString(destHost, destPort, localHost) + exception + ";" + see("UnknownHost")); } else if (exception instanceof SocketTimeoutException) { return wrapWithMessage(exception, "Call From " + localHost + " to " + destHost + ":" + destPort + " failed on socket timeout exception: " + exception + ";" + see("SocketTimeout")); } else if (exception instanceof NoRouteToHostException) { return wrapWithMessage(exception, "No Route to Host from " + localHost + " to " + destHost + ":" + destPort + " failed on socket timeout exception: " + exception + ";" + see("NoRouteToHost")); } else if (exception instanceof EOFException) { return wrapWithMessage(exception, "End of File Exception between " + getHostDetailsAsString(destHost, destPort, localHost) + ": " + exception + ";" + see("EOFException")); } else if (exception instanceof SocketException) { // Many of the predecessor exceptions are subclasses of SocketException, // so must be handled before this return wrapWithMessage(exception, "Call From " + localHost + " to " + destHost + ":" + destPort + " failed on socket exception: " + exception + ";" + see("SocketException")); } else { // Return instance of same type if Exception has a String constructor return wrapWithMessage(exception, "DestHost:destPort " + destHost + ":" + destPort + " , LocalHost:localPort " + localHost + ":" + localPort + ". Failed on local exception: " + exception); } } catch (IOException ex) { return (IOException) new IOException("Failed on local exception: " + exception + "; Host Details : " + getHostDetailsAsString(destHost, destPort, localHost)).initCause(exception); } } private static String see(final String entry) { return FOR_MORE_DETAILS_SEE + HADOOP_WIKI + entry; } @SuppressWarnings("unchecked") private static <T extends IOException> T wrapWithMessage(T exception, String msg) throws T { Class<? extends Throwable> clazz = exception.getClass(); try { Constructor<? extends Throwable> ctor = clazz.getConstructor(String.class); Throwable t = ctor.newInstance(msg); return (T) (t.initCause(exception)); } catch (Throwable e) { LOG.warn("Unable to wrap exception of type {}: it has no (String) " + "constructor", clazz, e); throw exception; } } /** * Get the host details as a string * @param destHost destinatioon host (nullable) * @param destPort destination port * @param localHost local host (nullable) * @return a string describing the destination host:port and the local host */ private static String getHostDetailsAsString(final String destHost, final int destPort, final String localHost) { StringBuilder hostDetails = new StringBuilder(27); hostDetails.append("local host is: ").append(quoteHost(localHost)).append("; "); hostDetails.append("destination host is: ").append(quoteHost(destHost)).append(":").append(destPort) .append("; "); return hostDetails.toString(); } /** * Quote a hostname if it is not null * @param hostname the hostname; nullable * @return a quoted hostname or {@link #UNKNOWN_HOST} if the hostname is null */ private static String quoteHost(final String hostname) { return (hostname != null) ? ("\"" + hostname + "\"") : UNKNOWN_HOST; } /** * @return true if the given string is a subnet specified * using CIDR notation, false otherwise */ public static boolean isValidSubnet(String subnet) { try { new SubnetUtils(subnet); return true; } catch (IllegalArgumentException iae) { return false; } } /** * Add all addresses associated with the given nif in the * given subnet to the given list. */ private static void addMatchingAddrs(NetworkInterface nif, SubnetInfo subnetInfo, List<InetAddress> addrs) { Enumeration<InetAddress> ifAddrs = nif.getInetAddresses(); while (ifAddrs.hasMoreElements()) { InetAddress ifAddr = ifAddrs.nextElement(); if (subnetInfo.isInRange(ifAddr.getHostAddress())) { addrs.add(ifAddr); } } } /** * Return an InetAddress for each interface that matches the * given subnet specified using CIDR notation. * * @param subnet subnet specified using CIDR notation * @param returnSubinterfaces * whether to return IPs associated with subinterfaces * @throws IllegalArgumentException if subnet is invalid */ public static List<InetAddress> getIPs(String subnet, boolean returnSubinterfaces) { List<InetAddress> addrs = new ArrayList<InetAddress>(); SubnetInfo subnetInfo = new SubnetUtils(subnet).getInfo(); Enumeration<NetworkInterface> nifs; try { nifs = NetworkInterface.getNetworkInterfaces(); } catch (SocketException e) { LOG.error("Unable to get host interfaces", e); return addrs; } while (nifs.hasMoreElements()) { NetworkInterface nif = nifs.nextElement(); // NB: adding addresses even if the nif is not up addMatchingAddrs(nif, subnetInfo, addrs); if (!returnSubinterfaces) { continue; } Enumeration<NetworkInterface> subNifs = nif.getSubInterfaces(); while (subNifs.hasMoreElements()) { addMatchingAddrs(subNifs.nextElement(), subnetInfo, addrs); } } return addrs; } /** * Return a free port number. There is no guarantee it will remain free, so * it should be used immediately. * * @returns A free port for binding a local socket */ public static int getFreeSocketPort() { int port = 0; try { ServerSocket s = new ServerSocket(0); port = s.getLocalPort(); s.close(); return port; } catch (IOException e) { // Could not get a free port. Return default port 0. } return port; } /** * Return an @{@link InetAddress} to bind to. If bindWildCardAddress is true * than returns null. * * @param localAddr * @param bindWildCardAddress * @returns InetAddress */ public static InetAddress bindToLocalAddress(InetAddress localAddr, boolean bindWildCardAddress) { if (!bindWildCardAddress) { return localAddr; } return null; } }