/**
* 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.ipc;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.BindException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.Channels;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.channels.WritableByteChannel;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.LinkedBlockingQueue;
import javax.security.sasl.Sasl;
import javax.security.sasl.SaslException;
import javax.security.sasl.SaslServer;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.IntWritable;
import static org.apache.hadoop.fs.CommonConfigurationKeys.*;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.ipc.metrics.RpcDetailedMetrics;
import org.apache.hadoop.ipc.metrics.RpcMetrics;
import org.apache.hadoop.security.AccessControlException;
import org.apache.hadoop.security.SaslRpcServer;
import org.apache.hadoop.security.SaslRpcServer.SaslStatus;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.SaslRpcServer.AuthMethod;
import org.apache.hadoop.security.SaslRpcServer.SaslDigestCallbackHandler;
import org.apache.hadoop.security.SaslRpcServer.SaslGssCallbackHandler;
import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;
import org.apache.hadoop.security.authorize.AuthorizationException;
import org.apache.hadoop.security.authorize.PolicyProvider;
import org.apache.hadoop.security.authorize.ProxyUsers;
import org.apache.hadoop.security.authorize.ServiceAuthorizationManager;
import org.apache.hadoop.security.token.SecretManager;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;
import org.apache.hadoop.security.token.TokenIdentifier;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.hadoop.util.StringUtils;
/** An abstract IPC service. IPC calls take a single {@link Writable} as a
* parameter, and return a {@link Writable} as their value. A service runs on
* a port and is defined by a parameter class and a value class.
*
* @see Client
*/
public abstract class Server {
private final boolean authorize;
private boolean isSecurityEnabled;
/**
* The first four bytes of Hadoop RPC connections
*/
public static final ByteBuffer HEADER = ByteBuffer.wrap("hrpc".getBytes());
// 1 : Introduce ping and server does not throw away RPCs
// 3 : Introduce the protocol into the RPC connection header
// 4 : Introduced SASL security layer
public static final byte CURRENT_VERSION = 4;
/**
* How many calls/handler are allowed in the queue.
*/
private static final int IPC_SERVER_HANDLER_QUEUE_SIZE_DEFAULT = 100;
private static final String IPC_SERVER_HANDLER_QUEUE_SIZE_KEY =
"ipc.server.handler.queue.size";
/**
* Initial and max size of response buffer
*/
static int INITIAL_RESP_BUF_SIZE = 10240;
static final String IPC_SERVER_RPC_MAX_RESPONSE_SIZE_KEY =
"ipc.server.max.response.size";
static final int IPC_SERVER_RPC_MAX_RESPONSE_SIZE_DEFAULT = 1024*1024;
public static final Log LOG = LogFactory.getLog(Server.class);
private static final Log AUDITLOG =
LogFactory.getLog("SecurityLogger."+Server.class.getName());
private static final String AUTH_FAILED_FOR = "Auth failed for ";
private static final String AUTH_SUCCESSFULL_FOR = "Auth successfull for ";
private static final ThreadLocal<Server> SERVER = new ThreadLocal<Server>();
private static final Map<String, Class<?>> PROTOCOL_CACHE =
new ConcurrentHashMap<String, Class<?>>();
static Class<?> getProtocolClass(String protocolName, Configuration conf)
throws ClassNotFoundException {
Class<?> protocol = PROTOCOL_CACHE.get(protocolName);
if (protocol == null) {
protocol = conf.getClassByName(protocolName);
PROTOCOL_CACHE.put(protocolName, protocol);
}
return protocol;
}
/** Returns the server instance called under or null. May be called under
* {@link #call(Writable, long)} implementations, and under {@link Writable}
* methods of paramters and return values. Permits applications to access
* the server context.*/
public static Server get() {
return SERVER.get();
}
/** This is set to Call object before Handler invokes an RPC and reset
* after the call returns.
*/
private static final ThreadLocal<Call> CurCall = new ThreadLocal<Call>();
/** Returns the remote side ip address when invoked inside an RPC
* Returns null incase of an error.
*/
public static InetAddress getRemoteIp() {
Call call = CurCall.get();
if (call != null) {
return call.connection.socket.getInetAddress();
}
return null;
}
/** Returns remote address as a string when invoked inside an RPC.
* Returns null in case of an error.
*/
public static String getRemoteAddress() {
InetAddress addr = getRemoteIp();
return (addr == null) ? null : addr.getHostAddress();
}
private String bindAddress;
private int port; // port we listen on
private int handlerCount; // number of handler threads
private Class<? extends Writable> paramClass; // class of call parameters
private int maxIdleTime; // the maximum idle time after
// which a client may be disconnected
private int thresholdIdleConnections; // the number of idle connections
// after which we will start
// cleaning up idle
// connections
int maxConnectionsToNuke; // the max number of
// connections to nuke
//during a cleanup
protected RpcMetrics rpcMetrics;
protected RpcDetailedMetrics rpcDetailedMetrics;
private Configuration conf;
private SecretManager<TokenIdentifier> secretManager;
private ServiceAuthorizationManager serviceAuthorizationManager = new ServiceAuthorizationManager();
private int maxQueueSize;
private final int maxRespSize;
private int socketSendBufferSize;
private final boolean tcpNoDelay; // if T then disable Nagle's Algorithm
volatile private boolean running = true; // true while server runs
private BlockingQueue<Call> callQueue; // queued calls
private List<Connection> connectionList =
Collections.synchronizedList(new LinkedList<Connection>());
//maintain a list
//of client connections
private Listener listener = null;
private Responder responder = null;
private int numConnections = 0;
private Handler[] handlers = null;
/**
* A convenience method to bind to a given address and report
* better exceptions if the address is not a valid host.
* @param socket the socket to bind
* @param address the address to bind to
* @param backlog the number of connections allowed in the queue
* @throws BindException if the address can't be bound
* @throws UnknownHostException if the address isn't a valid host name
* @throws IOException other random errors from bind
*/
public static void bind(ServerSocket socket, InetSocketAddress address,
int backlog) throws IOException {
try {
socket.bind(address, backlog);
} catch (BindException e) {
BindException bindException = new BindException("Problem binding to " + address
+ " : " + e.getMessage());
bindException.initCause(e);
throw bindException;
} catch (SocketException e) {
// If they try to bind to a different host's address, give a better
// error message.
if ("Unresolved address".equals(e.getMessage())) {
throw new UnknownHostException("Invalid hostname for server: " +
address.getHostName());
} else {
throw e;
}
}
}
/**
* Returns a handle to the rpcMetrics (required in tests)
* @return rpc metrics
*/
public RpcMetrics getRpcMetrics() {
return rpcMetrics;
}
/**
* Refresh the service authorization ACL for the service handled by this server.
*/
public void refreshServiceAcl(Configuration conf, PolicyProvider provider) {
serviceAuthorizationManager.refresh(conf, provider);
}
/**
* Returns a handle to the serviceAuthorizationManager (required in tests)
* @return instance of ServiceAuthorizationManager for this server
*/
//@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
public ServiceAuthorizationManager getServiceAuthorizationManager() {
return serviceAuthorizationManager;
}
/** A call queued for handling. */
private static class Call {
private int id; // the client's call id
private Writable param; // the parameter passed
private Connection connection; // connection to client
private long timestamp; // the time received when response is null
// the time served when response is not null
private ByteBuffer response; // the response for this call
public Call(int id, Writable param, Connection connection) {
this.id = id;
this.param = param;
this.connection = connection;
this.timestamp = System.currentTimeMillis();
this.response = null;
}
@Override
public String toString() {
return param.toString() + " from " + connection.toString();
}
public void setResponse(ByteBuffer response) {
this.response = response;
}
}
/** Listens on the socket. Creates jobs for the handler threads*/
private class Listener extends Thread {
private ServerSocketChannel acceptChannel = null; //the accept channel
private Selector selector = null; //the selector that we use for the server
private InetSocketAddress address; //the address we bind at
private Random rand = new Random();
private long lastCleanupRunTime = 0; //the last time when a cleanup connec-
//-tion (for idle connections) ran
private long cleanupInterval = 10000; //the minimum interval between
//two cleanup runs
private int backlogLength = conf.getInt("ipc.server.listen.queue.size", 128);
public Listener() throws IOException {
address = new InetSocketAddress(bindAddress, port);
// Create a new server socket and set to non blocking mode
acceptChannel = ServerSocketChannel.open();
acceptChannel.configureBlocking(false);
// Bind the server socket to the local host and port
bind(acceptChannel.socket(), address, backlogLength);
port = acceptChannel.socket().getLocalPort(); //Could be an ephemeral port
// create a selector;
selector= Selector.open();
// Register accepts on the server socket with the selector.
acceptChannel.register(selector, SelectionKey.OP_ACCEPT);
this.setName("IPC Server listener on " + port);
this.setDaemon(true);
}
/** cleanup connections from connectionList. Choose a random range
* to scan and also have a limit on the number of the connections
* that will be cleanedup per run. The criteria for cleanup is the time
* for which the connection was idle. If 'force' is true then all
* connections will be looked at for the cleanup.
*/
private void cleanupConnections(boolean force) {
if (force || numConnections > thresholdIdleConnections) {
long currentTime = System.currentTimeMillis();
if (!force && (currentTime - lastCleanupRunTime) < cleanupInterval) {
return;
}
int start = 0;
int end = numConnections - 1;
if (!force) {
start = rand.nextInt() % numConnections;
end = rand.nextInt() % numConnections;
int temp;
if (end < start) {
temp = start;
start = end;
end = temp;
}
}
int i = start;
int numNuked = 0;
while (i <= end) {
Connection c;
synchronized (connectionList) {
try {
c = connectionList.get(i);
} catch (Exception e) {return;}
}
if (c.timedOut(currentTime)) {
if (LOG.isDebugEnabled())
LOG.debug(getName() + ": disconnecting client " + c.getHostAddress());
closeConnection(c);
numNuked++;
end--;
c = null;
if (!force && numNuked == maxConnectionsToNuke) break;
}
else i++;
}
lastCleanupRunTime = System.currentTimeMillis();
}
}
@Override
public void run() {
LOG.info(getName() + ": starting");
SERVER.set(Server.this);
while (running) {
SelectionKey key = null;
try {
selector.select();
Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
while (iter.hasNext()) {
key = iter.next();
iter.remove();
try {
if (key.isValid()) {
if (key.isAcceptable())
doAccept(key);
else if (key.isReadable())
doRead(key);
}
} catch (IOException e) {
}
key = null;
}
} catch (OutOfMemoryError e) {
// we can run out of memory if we have too many threads
// log the event and sleep for a minute and give
// some thread(s) a chance to finish
LOG.warn("Out of Memory in server select", e);
closeCurrentConnection(key, e);
cleanupConnections(true);
try { Thread.sleep(60000); } catch (Exception ie) {}
} catch (InterruptedException e) {
if (running) { // unexpected -- log it
LOG.info(getName() + " caught: " +
StringUtils.stringifyException(e));
}
} catch (Exception e) {
closeCurrentConnection(key, e);
}
cleanupConnections(false);
}
LOG.info("Stopping " + this.getName());
synchronized (this) {
try {
acceptChannel.close();
selector.close();
} catch (IOException e) { }
selector= null;
acceptChannel= null;
// clean up all connections
while (!connectionList.isEmpty()) {
closeConnection(connectionList.remove(0));
}
}
}
private void closeCurrentConnection(SelectionKey key, Throwable e) {
if (key != null) {
Connection c = (Connection)key.attachment();
if (c != null) {
if (LOG.isDebugEnabled())
LOG.debug(getName() + ": disconnecting client " + c.getHostAddress());
closeConnection(c);
c = null;
}
}
}
InetSocketAddress getAddress() {
return (InetSocketAddress)acceptChannel.socket().getLocalSocketAddress();
}
void doAccept(SelectionKey key) throws IOException, OutOfMemoryError {
Connection c = null;
ServerSocketChannel server = (ServerSocketChannel) key.channel();
// accept up to 10 connections
for (int i=0; i<10; i++) {
SocketChannel channel = server.accept();
if (channel==null) return;
channel.configureBlocking(false);
channel.socket().setTcpNoDelay(tcpNoDelay);
SelectionKey readKey = channel.register(selector, SelectionKey.OP_READ);
c = new Connection(readKey, channel, System.currentTimeMillis());
readKey.attach(c);
synchronized (connectionList) {
connectionList.add(numConnections, c);
numConnections++;
}
if (LOG.isDebugEnabled())
LOG.debug("Server connection from " + c.toString() +
"; # active connections: " + numConnections +
"; # queued calls: " + callQueue.size());
}
}
void doRead(SelectionKey key) throws InterruptedException {
int count = 0;
Connection c = (Connection)key.attachment();
if (c == null) {
return;
}
c.setLastContact(System.currentTimeMillis());
try {
count = c.readAndProcess();
} catch (InterruptedException ieo) {
LOG.info(getName() + ": readAndProcess caught InterruptedException", ieo);
throw ieo;
} catch (Exception e) {
LOG.info(getName() + ": readAndProcess threw exception " + e + ". Count of bytes read: " + count, e);
count = -1; //so that the (count < 0) block is executed
}
if (count < 0) {
if (LOG.isDebugEnabled())
LOG.debug(getName() + ": disconnecting client " +
c + ". Number of active connections: "+
numConnections);
closeConnection(c);
c = null;
}
else {
c.setLastContact(System.currentTimeMillis());
}
}
synchronized void doStop() {
if (selector != null) {
selector.wakeup();
Thread.yield();
}
if (acceptChannel != null) {
try {
acceptChannel.socket().close();
} catch (IOException e) {
LOG.info(getName() + ":Exception in closing listener socket. " + e);
}
}
}
}
// Sends responses of RPC back to clients.
private class Responder extends Thread {
private Selector writeSelector;
private int pending; // connections waiting to register
final static int PURGE_INTERVAL = 900000; // 15mins
Responder() throws IOException {
this.setName("IPC Server Responder");
this.setDaemon(true);
writeSelector = Selector.open(); // create a selector
pending = 0;
}
@Override
public void run() {
LOG.info(getName() + ": starting");
SERVER.set(Server.this);
long lastPurgeTime = 0; // last check for old calls.
while (running) {
try {
waitPending(); // If a channel is being registered, wait.
writeSelector.select(PURGE_INTERVAL);
Iterator<SelectionKey> iter = writeSelector.selectedKeys().iterator();
while (iter.hasNext()) {
SelectionKey key = iter.next();
iter.remove();
try {
if (key.isValid() && key.isWritable()) {
doAsyncWrite(key);
}
} catch (IOException e) {
LOG.info(getName() + ": doAsyncWrite threw exception " + e);
}
}
long now = System.currentTimeMillis();
if (now < lastPurgeTime + PURGE_INTERVAL) {
continue;
}
lastPurgeTime = now;
//
// If there were some calls that have not been sent out for a
// long time, discard them.
//
LOG.debug("Checking for old call responses.");
ArrayList<Call> calls;
// get the list of channels from list of keys.
synchronized (writeSelector.keys()) {
calls = new ArrayList<Call>(writeSelector.keys().size());
iter = writeSelector.keys().iterator();
while (iter.hasNext()) {
SelectionKey key = iter.next();
Call call = (Call)key.attachment();
if (call != null && key.channel() == call.connection.channel) {
calls.add(call);
}
}
}
for(Call call : calls) {
try {
doPurge(call, now);
} catch (IOException e) {
LOG.warn("Error in purging old calls " + e);
}
}
} catch (OutOfMemoryError e) {
//
// we can run out of memory if we have too many threads
// log the event and sleep for a minute and give
// some thread(s) a chance to finish
//
LOG.warn("Out of Memory in server select", e);
try { Thread.sleep(60000); } catch (Exception ie) {}
} catch (Exception e) {
LOG.warn("Exception in Responder " +
StringUtils.stringifyException(e));
}
}
LOG.info("Stopping " + this.getName());
}
private void doAsyncWrite(SelectionKey key) throws IOException {
Call call = (Call)key.attachment();
if (call == null) {
return;
}
if (key.channel() != call.connection.channel) {
throw new IOException("doAsyncWrite: bad channel");
}
synchronized(call.connection.responseQueue) {
if (processResponse(call.connection.responseQueue, false)) {
try {
key.interestOps(0);
} catch (CancelledKeyException e) {
/* The Listener/reader might have closed the socket.
* We don't explicitly cancel the key, so not sure if this will
* ever fire.
* This warning could be removed.
*/
LOG.warn("Exception while changing ops : " + e);
}
}
}
}
//
// Remove calls that have been pending in the responseQueue
// for a long time.
//
private void doPurge(Call call, long now) throws IOException {
LinkedList<Call> responseQueue = call.connection.responseQueue;
synchronized (responseQueue) {
Iterator<Call> iter = responseQueue.listIterator(0);
while (iter.hasNext()) {
call = iter.next();
if (now > call.timestamp + PURGE_INTERVAL) {
closeConnection(call.connection);
break;
}
}
}
}
// Processes one response. Returns true if there are no more pending
// data for this channel.
//
private boolean processResponse(LinkedList<Call> responseQueue,
boolean inHandler) throws IOException {
boolean error = true;
boolean done = false; // there is more data for this channel.
int numElements = 0;
Call call = null;
try {
synchronized (responseQueue) {
//
// If there are no items for this channel, then we are done
//
numElements = responseQueue.size();
if (numElements == 0) {
error = false;
return true; // no more data for this channel.
}
//
// Extract the first call
//
call = responseQueue.removeFirst();
SocketChannel channel = call.connection.channel;
if (LOG.isDebugEnabled()) {
LOG.debug(getName() + ": responding to #" + call.id + " from " +
call.connection);
}
//
// Send as much data as we can in the non-blocking fashion
//
int numBytes = channelWrite(channel, call.response);
if (numBytes < 0) {
return true;
}
if (!call.response.hasRemaining()) {
call.connection.decRpcCount();
if (numElements == 1) { // last call fully processes.
done = true; // no more data for this channel.
} else {
done = false; // more calls pending to be sent.
}
if (LOG.isDebugEnabled()) {
LOG.debug(getName() + ": responding to #" + call.id + " from " +
call.connection + " Wrote " + numBytes + " bytes.");
}
} else {
//
// If we were unable to write the entire response out, then
// insert in Selector queue.
//
call.connection.responseQueue.addFirst(call);
if (inHandler) {
// set the serve time when the response has to be sent later
call.timestamp = System.currentTimeMillis();
incPending();
try {
// Wakeup the thread blocked on select, only then can the call
// to channel.register() complete.
writeSelector.wakeup();
channel.register(writeSelector, SelectionKey.OP_WRITE, call);
} catch (ClosedChannelException e) {
//Its ok. channel might be closed else where.
done = true;
} finally {
decPending();
}
}
if (LOG.isDebugEnabled()) {
LOG.debug(getName() + ": responding to #" + call.id + " from " +
call.connection + " Wrote partial " + numBytes +
" bytes.");
}
}
error = false; // everything went off well
}
} finally {
if (error && call != null) {
LOG.warn(getName()+", call " + call + ": output error");
done = true; // error. no more data for this channel.
closeConnection(call.connection);
}
}
return done;
}
//
// Enqueue a response from the application.
//
void doRespond(Call call) throws IOException {
synchronized (call.connection.responseQueue) {
call.connection.responseQueue.addLast(call);
if (call.connection.responseQueue.size() == 1) {
processResponse(call.connection.responseQueue, true);
}
}
}
private synchronized void incPending() { // call waiting to be enqueued.
pending++;
}
private synchronized void decPending() { // call done enqueueing.
pending--;
notify();
}
private synchronized void waitPending() throws InterruptedException {
while (pending > 0) {
wait();
}
}
}
/** Reads calls from a connection and queues them for handling. */
public class Connection {
private boolean rpcHeaderRead = false; // if initial rpc header is read
private boolean headerRead = false; //if the connection header that
//follows version is read.
private SocketChannel channel;
private ByteBuffer data;
private ByteBuffer dataLengthBuffer;
private LinkedList<Call> responseQueue;
private volatile int rpcCount = 0; // number of outstanding rpcs
private long lastContact;
private int dataLength;
private Socket socket;
// Cache the remote host & port info so that even if the socket is
// disconnected, we can say where it used to connect to.
private String hostAddress;
private String hostName;
private int remotePort;
ConnectionHeader header = new ConnectionHeader();
Class<?> protocol;
boolean useSasl;
SaslServer saslServer;
private AuthMethod authMethod;
private boolean saslContextEstablished;
private boolean skipInitialSaslHandshake;
private ByteBuffer rpcHeaderBuffer;
private ByteBuffer unwrappedData;
private ByteBuffer unwrappedDataLengthBuffer;
UserGroupInformation user = null;
public UserGroupInformation attemptingUser = null; // user name before auth
// Fake 'call' for failed authorization response
private final int AUTHROIZATION_FAILED_CALLID = -1;
private final Call authFailedCall =
new Call(AUTHROIZATION_FAILED_CALLID, null, this);
private ByteArrayOutputStream authFailedResponse = new ByteArrayOutputStream();
// Fake 'call' for SASL context setup
private static final int SASL_CALLID = -33;
private final Call saslCall = new Call(SASL_CALLID, null, this);
private final ByteArrayOutputStream saslResponse = new ByteArrayOutputStream();
private boolean useWrap = false;
public Connection(SelectionKey key, SocketChannel channel,
long lastContact) {
this.channel = channel;
this.lastContact = lastContact;
this.data = null;
this.dataLengthBuffer = ByteBuffer.allocate(4);
this.unwrappedData = null;
this.unwrappedDataLengthBuffer = ByteBuffer.allocate(4);
this.socket = channel.socket();
InetAddress addr = socket.getInetAddress();
if (addr == null) {
this.hostAddress = "*Unknown*";
} else {
this.hostAddress = addr.getHostAddress();
this.hostName = addr.getCanonicalHostName();
}
this.remotePort = socket.getPort();
this.responseQueue = new LinkedList<Call>();
if (socketSendBufferSize != 0) {
try {
socket.setSendBufferSize(socketSendBufferSize);
} catch (IOException e) {
LOG.warn("Connection: unable to set socket send buffer size to " +
socketSendBufferSize);
}
}
}
@Override
public String toString() {
return getHostAddress() + ":" + remotePort;
}
public String getHostAddress() {
return hostAddress;
}
public String getHostName() {
return hostName;
}
public void setLastContact(long lastContact) {
this.lastContact = lastContact;
}
public long getLastContact() {
return lastContact;
}
/* Return true if the connection has no outstanding rpc */
private boolean isIdle() {
return rpcCount == 0;
}
/* Decrement the outstanding RPC count */
private void decRpcCount() {
rpcCount--;
}
/* Increment the outstanding RPC count */
private void incRpcCount() {
rpcCount++;
}
private boolean timedOut(long currentTime) {
if (isIdle() && currentTime - lastContact > maxIdleTime)
return true;
return false;
}
private UserGroupInformation getAuthorizedUgi(String authorizedId)
throws IOException {
if (authMethod == SaslRpcServer.AuthMethod.DIGEST) {
TokenIdentifier tokenId = SaslRpcServer.getIdentifier(authorizedId,
secretManager);
UserGroupInformation ugi = tokenId.getUser();
if (ugi == null) {
throw new AccessControlException(
"Can't retrieve username from tokenIdentifier.");
}
ugi.addTokenIdentifier(tokenId);
return ugi;
} else {
return UserGroupInformation.createRemoteUser(authorizedId);
}
}
private void saslReadAndProcess(byte[] saslToken) throws IOException,
InterruptedException {
if (!saslContextEstablished) {
byte[] replyToken = null;
try {
if (saslServer == null) {
switch (authMethod) {
case DIGEST:
if (secretManager == null) {
throw new AccessControlException(
"Server is not configured to do DIGEST authentication.");
}
saslServer = Sasl.createSaslServer(AuthMethod.DIGEST
.getMechanismName(), null, SaslRpcServer.SASL_DEFAULT_REALM,
SaslRpcServer.SASL_PROPS, new SaslDigestCallbackHandler(
secretManager, this));
break;
default:
UserGroupInformation current = UserGroupInformation
.getCurrentUser();
String fullName = current.getUserName();
if (LOG.isDebugEnabled())
LOG.debug("Kerberos principal name is " + fullName);
final String names[] = SaslRpcServer.splitKerberosName(fullName);
if (names.length != 3) {
throw new AccessControlException(
"Kerberos principal name does NOT have the expected "
+ "hostname part: " + fullName);
}
current.doAs(new PrivilegedExceptionAction<Object>() {
@Override
public Object run() throws SaslException {
saslServer = Sasl.createSaslServer(AuthMethod.KERBEROS
.getMechanismName(), names[0], names[1],
SaslRpcServer.SASL_PROPS, new SaslGssCallbackHandler());
return null;
}
});
}
if (saslServer == null)
throw new AccessControlException(
"Unable to find SASL server implementation for "
+ authMethod.getMechanismName());
if (LOG.isDebugEnabled())
LOG.debug("Created SASL server with mechanism = "
+ authMethod.getMechanismName());
}
if (LOG.isDebugEnabled())
LOG.debug("Have read input token of size " + saslToken.length
+ " for processing by saslServer.evaluateResponse()");
replyToken = saslServer.evaluateResponse(saslToken);
} catch (IOException e) {
IOException sendToClient = e;
Throwable cause = e;
while (cause != null) {
if (cause instanceof InvalidToken) {
sendToClient = (InvalidToken) cause;
break;
}
cause = cause.getCause();
}
doSaslReply(SaslStatus.ERROR, null, sendToClient.getClass().getName(),
sendToClient.getLocalizedMessage());
rpcMetrics.authenticationFailures.inc();
String clientIP = this.toString();
// attempting user could be null
AUDITLOG.warn(AUTH_FAILED_FOR + clientIP + ":" + attemptingUser);
throw e;
}
if (replyToken != null) {
if (LOG.isDebugEnabled())
LOG.debug("Will send token of size " + replyToken.length
+ " from saslServer.");
doSaslReply(SaslStatus.SUCCESS, new BytesWritable(replyToken), null,
null);
}
if (saslServer.isComplete()) {
LOG.info("SASL server context established. Negotiated QoP is "
+ saslServer.getNegotiatedProperty(Sasl.QOP));
String qop = (String) saslServer.getNegotiatedProperty(Sasl.QOP);
useWrap = qop != null && !"auth".equalsIgnoreCase(qop);
user = getAuthorizedUgi(saslServer.getAuthorizationID());
LOG.info("SASL server successfully authenticated client: " + user);
rpcMetrics.authenticationSuccesses.inc();
AUDITLOG.info(AUTH_SUCCESSFULL_FOR + user);
saslContextEstablished = true;
}
} else {
if (LOG.isDebugEnabled())
LOG.debug("Have read input token of size " + saslToken.length
+ " for processing by saslServer.unwrap()");
if (!useWrap) {
processOneRpc(saslToken);
} else {
byte[] plaintextData = saslServer.unwrap(saslToken, 0,
saslToken.length);
processUnwrappedData(plaintextData);
}
}
}
private void doSaslReply(SaslStatus status, Writable rv,
String errorClass, String error) throws IOException {
saslResponse.reset();
DataOutputStream out = new DataOutputStream(saslResponse);
out.writeInt(status.state); // write status
if (status == SaslStatus.SUCCESS) {
rv.write(out);
} else {
WritableUtils.writeString(out, errorClass);
WritableUtils.writeString(out, error);
}
saslCall.setResponse(ByteBuffer.wrap(saslResponse.toByteArray()));
responder.doRespond(saslCall);
}
private void disposeSasl() {
if (saslServer != null) {
try {
saslServer.dispose();
} catch (SaslException ignored) {
}
}
}
public int readAndProcess() throws IOException, InterruptedException {
while (true) {
/* Read at most one RPC. If the header is not read completely yet
* then iterate until we read first RPC or until there is no data left.
*/
int count = -1;
if (dataLengthBuffer.remaining() > 0) {
count = channelRead(channel, dataLengthBuffer);
if (count < 0 || dataLengthBuffer.remaining() > 0)
return count;
}
if (!rpcHeaderRead) {
//Every connection is expected to send the header.
if (rpcHeaderBuffer == null) {
rpcHeaderBuffer = ByteBuffer.allocate(2);
}
count = channelRead(channel, rpcHeaderBuffer);
if (count < 0 || rpcHeaderBuffer.remaining() > 0) {
return count;
}
int version = rpcHeaderBuffer.get(0);
byte[] method = new byte[] {rpcHeaderBuffer.get(1)};
authMethod = AuthMethod.read(new DataInputStream(
new ByteArrayInputStream(method)));
dataLengthBuffer.flip();
if (!HEADER.equals(dataLengthBuffer) || version != CURRENT_VERSION) {
//Warning is ok since this is not supposed to happen.
LOG.warn("Incorrect header or version mismatch from " +
hostAddress + ":" + remotePort +
" got version " + version +
" expected version " + CURRENT_VERSION);
return -1;
}
dataLengthBuffer.clear();
if (authMethod == null) {
throw new IOException("Unable to read authentication method");
}
if (isSecurityEnabled && authMethod == AuthMethod.SIMPLE) {
AccessControlException ae = new AccessControlException(
"Authentication is required");
setupResponse(authFailedResponse, authFailedCall, Status.FATAL,
null, ae.getClass().getName(), ae.getMessage());
responder.doRespond(authFailedCall);
throw ae;
}
if (!isSecurityEnabled && authMethod != AuthMethod.SIMPLE) {
doSaslReply(SaslStatus.SUCCESS, new IntWritable(
SaslRpcServer.SWITCH_TO_SIMPLE_AUTH), null, null);
authMethod = AuthMethod.SIMPLE;
// client has already sent the initial Sasl message and we
// should ignore it. Both client and server should fall back
// to simple auth from now on.
skipInitialSaslHandshake = true;
}
if (authMethod != AuthMethod.SIMPLE) {
useSasl = true;
}
rpcHeaderBuffer = null;
rpcHeaderRead = true;
continue;
}
if (data == null) {
dataLengthBuffer.flip();
dataLength = dataLengthBuffer.getInt();
if (dataLength == Client.PING_CALL_ID) {
if(!useWrap) { //covers the !useSasl too
dataLengthBuffer.clear();
return 0; //ping message
}
}
if (dataLength < 0) {
LOG.warn("Unexpected data length " + dataLength + "!! from " +
getHostAddress());
}
data = ByteBuffer.allocate(dataLength);
}
count = channelRead(channel, data);
if (data.remaining() == 0) {
dataLengthBuffer.clear();
data.flip();
if (skipInitialSaslHandshake) {
data = null;
skipInitialSaslHandshake = false;
continue;
}
boolean isHeaderRead = headerRead;
if (useSasl) {
saslReadAndProcess(data.array());
} else {
processOneRpc(data.array());
}
data = null;
if (!isHeaderRead) {
continue;
}
}
return count;
}
}
/// Reads the connection header following version
private void processHeader(byte[] buf) throws IOException {
DataInputStream in =
new DataInputStream(new ByteArrayInputStream(buf));
header.readFields(in);
try {
String protocolClassName = header.getProtocol();
if (protocolClassName != null) {
protocol = getProtocolClass(header.getProtocol(), conf);
}
} catch (ClassNotFoundException cnfe) {
throw new IOException("Unknown protocol: " + header.getProtocol());
}
UserGroupInformation protocolUser = header.getUgi();
if (!useSasl) {
user = protocolUser;
if (user != null) {
user.setAuthenticationMethod(AuthMethod.SIMPLE.authenticationMethod);
}
} else {
// user is authenticated
user.setAuthenticationMethod(authMethod.authenticationMethod);
//Now we check if this is a proxy user case. If the protocol user is
//different from the 'user', it is a proxy user scenario. However,
//this is not allowed if user authenticated with DIGEST.
if ((protocolUser != null)
&& (!protocolUser.getUserName().equals(user.getUserName()))) {
if (authMethod == AuthMethod.DIGEST) {
// Not allowed to doAs if token authentication is used
throw new AccessControlException("Authenticated user (" + user
+ ") doesn't match what the client claims to be ("
+ protocolUser + ")");
} else {
// Effective user can be different from authenticated user
// for simple auth or kerberos auth
// The user is the real user. Now we create a proxy user
UserGroupInformation realUser = user;
user = UserGroupInformation.createProxyUser(protocolUser
.getUserName(), realUser);
// Now the user is a proxy user, set Authentication method Proxy.
user.setAuthenticationMethod(AuthenticationMethod.PROXY);
}
}
}
}
private void processUnwrappedData(byte[] inBuf) throws IOException,
InterruptedException {
ReadableByteChannel ch = Channels.newChannel(new ByteArrayInputStream(
inBuf));
// Read all RPCs contained in the inBuf, even partial ones
while (true) {
int count = -1;
if (unwrappedDataLengthBuffer.remaining() > 0) {
count = channelRead(ch, unwrappedDataLengthBuffer);
if (count <= 0 || unwrappedDataLengthBuffer.remaining() > 0)
return;
}
if (unwrappedData == null) {
unwrappedDataLengthBuffer.flip();
int unwrappedDataLength = unwrappedDataLengthBuffer.getInt();
if (unwrappedDataLength == Client.PING_CALL_ID) {
if (LOG.isDebugEnabled())
LOG.debug("Received ping message");
unwrappedDataLengthBuffer.clear();
continue; // ping message
}
unwrappedData = ByteBuffer.allocate(unwrappedDataLength);
}
count = channelRead(ch, unwrappedData);
if (count <= 0 || unwrappedData.remaining() > 0)
return;
if (unwrappedData.remaining() == 0) {
unwrappedDataLengthBuffer.clear();
unwrappedData.flip();
processOneRpc(unwrappedData.array());
unwrappedData = null;
}
}
}
private void processOneRpc(byte[] buf) throws IOException,
InterruptedException {
if (headerRead) {
processData(buf);
} else {
processHeader(buf);
headerRead = true;
if (!authorizeConnection()) {
throw new AccessControlException("Connection from " + this
+ " for protocol " + header.getProtocol()
+ " is unauthorized for user " + user);
}
}
}
private void processData(byte[] buf) throws IOException, InterruptedException {
DataInputStream dis =
new DataInputStream(new ByteArrayInputStream(buf));
int id = dis.readInt(); // try to read an id
if (LOG.isDebugEnabled())
LOG.debug(" got #" + id);
Writable param = ReflectionUtils.newInstance(paramClass, conf);//read param
param.readFields(dis);
Call call = new Call(id, param, this);
callQueue.put(call); // queue the call; maybe blocked here
incRpcCount(); // Increment the rpc count
}
private boolean authorizeConnection() throws IOException {
try {
// If auth method is DIGEST, the token was obtained by the
// real user for the effective user, therefore not required to
// authorize real user. doAs is allowed only for simple or kerberos
// authentication
if (user != null && user.getRealUser() != null
&& (authMethod != AuthMethod.DIGEST)) {
ProxyUsers.authorize(user, this.getHostAddress(), conf);
}
authorize(user, header, getHostName());
if (LOG.isDebugEnabled()) {
LOG.debug("Successfully authorized " + header);
}
rpcMetrics.authorizationSuccesses.inc();
} catch (AuthorizationException ae) {
rpcMetrics.authorizationFailures.inc();
setupResponse(authFailedResponse, authFailedCall, Status.FATAL, null,
ae.getClass().getName(), ae.getMessage());
responder.doRespond(authFailedCall);
return false;
}
return true;
}
private synchronized void close() throws IOException {
disposeSasl();
data = null;
dataLengthBuffer = null;
if (!channel.isOpen())
return;
try {socket.shutdownOutput();} catch(Exception e) {}
if (channel.isOpen()) {
try {channel.close();} catch(Exception e) {}
}
try {socket.close();} catch(Exception e) {}
}
}
/** Handles queued calls . */
private class Handler extends Thread {
public Handler(int instanceNumber) {
this.setDaemon(true);
this.setName("IPC Server handler "+ instanceNumber + " on " + port);
}
@Override
public void run() {
LOG.info(getName() + ": starting");
SERVER.set(Server.this);
ByteArrayOutputStream buf =
new ByteArrayOutputStream(INITIAL_RESP_BUF_SIZE);
while (running) {
try {
final Call call = callQueue.take(); // pop the queue; maybe blocked here
if (LOG.isDebugEnabled())
LOG.debug(getName() + ": has #" + call.id + " from " +
call.connection);
String errorClass = null;
String error = null;
Writable value = null;
CurCall.set(call);
try {
// Make the call as the user via Subject.doAs, thus associating
// the call with the Subject
if (call.connection.user == null) {
value = call(call.connection.protocol, call.param,
call.timestamp);
} else {
value =
call.connection.user.doAs
(new PrivilegedExceptionAction<Writable>() {
@Override
public Writable run() throws Exception {
// make the call
return call(call.connection.protocol,
call.param, call.timestamp);
}
}
);
}
} catch (Throwable e) {
LOG.info(getName()+", call "+call+": error: " + e, e);
errorClass = e.getClass().getName();
error = StringUtils.stringifyException(e);
}
CurCall.set(null);
synchronized (call.connection.responseQueue) {
// setupResponse() needs to be sync'ed together with
// responder.doResponse() since setupResponse may use
// SASL to encrypt response data and SASL enforces
// its own message ordering.
setupResponse(buf, call,
(error == null) ? Status.SUCCESS : Status.ERROR,
value, errorClass, error);
// Discard the large buf and reset it back to
// smaller size to freeup heap
if (buf.size() > maxRespSize) {
LOG.warn("Large response size " + buf.size() + " for call " +
call.toString());
buf = new ByteArrayOutputStream(INITIAL_RESP_BUF_SIZE);
}
responder.doRespond(call);
}
} catch (InterruptedException e) {
if (running) { // unexpected -- log it
LOG.info(getName() + " caught: " +
StringUtils.stringifyException(e));
}
} catch (Exception e) {
LOG.info(getName() + " caught: " +
StringUtils.stringifyException(e));
}
}
LOG.info(getName() + ": exiting");
}
}
protected Server(String bindAddress, int port,
Class<? extends Writable> paramClass, int handlerCount,
Configuration conf)
throws IOException
{
this(bindAddress, port, paramClass, handlerCount, conf, Integer.toString(port), null);
}
protected Server(String bindAddress, int port,
Class<? extends Writable> paramClass, int handlerCount,
Configuration conf, String serverName)
throws IOException
{
this(bindAddress, port, paramClass, handlerCount, conf, serverName, null);
}
/** Constructs a server listening on the named port and address. Parameters passed must
* be of the named class. The <code>handlerCount</handlerCount> determines
* the number of handler threads that will be used to process calls.
*
*/
@SuppressWarnings("unchecked")
protected Server(String bindAddress, int port,
Class<? extends Writable> paramClass, int handlerCount,
Configuration conf, String serverName, SecretManager<? extends TokenIdentifier> secretManager)
throws IOException {
this.bindAddress = bindAddress;
this.conf = conf;
this.port = port;
this.paramClass = paramClass;
this.handlerCount = handlerCount;
this.socketSendBufferSize = 0;
this.maxQueueSize = handlerCount * conf.getInt(
IPC_SERVER_HANDLER_QUEUE_SIZE_KEY,
IPC_SERVER_HANDLER_QUEUE_SIZE_DEFAULT);
this.maxRespSize = conf.getInt(IPC_SERVER_RPC_MAX_RESPONSE_SIZE_KEY,
IPC_SERVER_RPC_MAX_RESPONSE_SIZE_DEFAULT);
this.callQueue = new LinkedBlockingQueue<Call>(maxQueueSize);
this.maxIdleTime = 2*conf.getInt("ipc.client.connection.maxidletime", 1000);
this.maxConnectionsToNuke = conf.getInt("ipc.client.kill.max", 10);
this.thresholdIdleConnections = conf.getInt("ipc.client.idlethreshold", 4000);
this.secretManager = (SecretManager<TokenIdentifier>) secretManager;
this.authorize =
conf.getBoolean(HADOOP_SECURITY_AUTHORIZATION, false);
this.isSecurityEnabled = UserGroupInformation.isSecurityEnabled();
// Start the listener here and let it bind to the port
listener = new Listener();
this.port = listener.getAddress().getPort();
this.rpcMetrics = new RpcMetrics(serverName,
Integer.toString(this.port), this);
this.rpcDetailedMetrics = new RpcDetailedMetrics(serverName,
Integer.toString(this.port));
this.tcpNoDelay = conf.getBoolean("ipc.server.tcpnodelay", false);
// Create the responder here
responder = new Responder();
if (isSecurityEnabled) {
SaslRpcServer.init(conf);
}
}
private void closeConnection(Connection connection) {
synchronized (connectionList) {
if (connectionList.remove(connection))
numConnections--;
}
try {
connection.close();
} catch (IOException e) {
}
}
/**
* Setup response for the IPC Call.
*
* @param response buffer to serialize the response into
* @param call {@link Call} to which we are setting up the response
* @param status {@link Status} of the IPC call
* @param rv return value for the IPC Call, if the call was successful
* @param errorClass error class, if the the call failed
* @param error error message, if the call failed
* @throws IOException
*/
private void setupResponse(ByteArrayOutputStream response,
Call call, Status status,
Writable rv, String errorClass, String error)
throws IOException {
response.reset();
DataOutputStream out = new DataOutputStream(response);
out.writeInt(call.id); // write call id
out.writeInt(status.state); // write status
if (status == Status.SUCCESS) {
rv.write(out);
} else {
WritableUtils.writeString(out, errorClass);
WritableUtils.writeString(out, error);
}
if (call.connection.useWrap) {
wrapWithSasl(response, call);
}
call.setResponse(ByteBuffer.wrap(response.toByteArray()));
}
private void wrapWithSasl(ByteArrayOutputStream response, Call call)
throws IOException {
if (call.connection.useSasl) {
byte[] token = response.toByteArray();
// synchronization may be needed since there can be multiple Handler
// threads using saslServer to wrap responses.
synchronized (call.connection.saslServer) {
token = call.connection.saslServer.wrap(token, 0, token.length);
}
if (LOG.isDebugEnabled())
LOG.debug("Adding saslServer wrapped token of size " + token.length
+ " as call response.");
response.reset();
DataOutputStream saslOut = new DataOutputStream(response);
saslOut.writeInt(token.length);
saslOut.write(token, 0, token.length);
}
}
Configuration getConf() {
return conf;
}
/** for unit testing only, should be called before server is started */
void disableSecurity() {
this.isSecurityEnabled = false;
}
/** for unit testing only, should be called before server is started */
void enableSecurity() {
this.isSecurityEnabled = true;
}
/** Sets the socket buffer size used for responding to RPCs */
public void setSocketSendBufSize(int size) { this.socketSendBufferSize = size; }
/** Starts the service. Must be called before any calls will be handled. */
public synchronized void start() {
responder.start();
listener.start();
handlers = new Handler[handlerCount];
for (int i = 0; i < handlerCount; i++) {
handlers[i] = new Handler(i);
handlers[i].start();
}
}
/** Stops the service. No new calls will be handled after this is called. */
public synchronized void stop() {
LOG.info("Stopping server on " + port);
running = false;
if (handlers != null) {
for (int i = 0; i < handlerCount; i++) {
if (handlers[i] != null) {
handlers[i].interrupt();
}
}
}
listener.interrupt();
listener.doStop();
responder.interrupt();
notifyAll();
if (this.rpcMetrics != null) {
this.rpcMetrics.shutdown();
}
if (this.rpcDetailedMetrics != null) {
this.rpcDetailedMetrics.shutdown();
}
}
/** Wait for the server to be stopped.
* Does not wait for all subthreads to finish.
* See {@link #stop()}.
*/
public synchronized void join() throws InterruptedException {
while (running) {
wait();
}
}
/**
* Return the socket (ip+port) on which the RPC server is listening to.
* @return the socket (ip+port) on which the RPC server is listening to.
*/
public synchronized InetSocketAddress getListenerAddress() {
return listener.getAddress();
}
/**
* Called for each call.
* @deprecated Use {@link #call(Class, Writable, long)} instead
*/
@Deprecated
public Writable call(Writable param, long receiveTime) throws IOException {
return call(null, param, receiveTime);
}
/** Called for each call. */
public abstract Writable call(Class<?> protocol,
Writable param, long receiveTime)
throws IOException;
/**
* Authorize the incoming client connection.
*
* @param user client user
* @param connection incoming connection
* @param hostname fully-qualified domain name of incoming connection
* @throws AuthorizationException when the client isn't authorized to talk the protocol
*/
public void authorize(UserGroupInformation user,
ConnectionHeader connection,
String hostname
) throws AuthorizationException {
if (authorize) {
Class<?> protocol = null;
try {
protocol = getProtocolClass(connection.getProtocol(), getConf());
} catch (ClassNotFoundException cfne) {
throw new AuthorizationException("Unknown protocol: " +
connection.getProtocol());
}
serviceAuthorizationManager.authorize(user, protocol, getConf(), hostname);
}
}
/**
* The number of open RPC conections
* @return the number of open rpc connections
*/
public int getNumOpenConnections() {
return numConnections;
}
/**
* The number of rpc calls in the queue.
* @return The number of rpc calls in the queue.
*/
public int getCallQueueLen() {
return callQueue.size();
}
/**
* When the read or write buffer size is larger than this limit, i/o will be
* done in chunks of this size. Most RPC requests and responses would be
* be smaller.
*/
private static int NIO_BUFFER_LIMIT = 8*1024; //should not be more than 64KB.
/**
* This is a wrapper around {@link WritableByteChannel#write(ByteBuffer)}.
* If the amount of data is large, it writes to channel in smaller chunks.
* This is to avoid jdk from creating many direct buffers as the size of
* buffer increases. This also minimizes extra copies in NIO layer
* as a result of multiple write operations required to write a large
* buffer.
*
* @see WritableByteChannel#write(ByteBuffer)
*/
private int channelWrite(WritableByteChannel channel,
ByteBuffer buffer) throws IOException {
int count = (buffer.remaining() <= NIO_BUFFER_LIMIT) ?
channel.write(buffer) : channelIO(null, channel, buffer);
if (count > 0) {
rpcMetrics.sentBytes.inc(count);
}
return count;
}
/**
* This is a wrapper around {@link ReadableByteChannel#read(ByteBuffer)}.
* If the amount of data is large, it writes to channel in smaller chunks.
* This is to avoid jdk from creating many direct buffers as the size of
* ByteBuffer increases. There should not be any performance degredation.
*
* @see ReadableByteChannel#read(ByteBuffer)
*/
private int channelRead(ReadableByteChannel channel,
ByteBuffer buffer) throws IOException {
int count = (buffer.remaining() <= NIO_BUFFER_LIMIT) ?
channel.read(buffer) : channelIO(channel, null, buffer);
if (count > 0) {
rpcMetrics.receivedBytes.inc(count);
}
return count;
}
/**
* Helper for {@link #channelRead(ReadableByteChannel, ByteBuffer)}
* and {@link #channelWrite(WritableByteChannel, ByteBuffer)}. Only
* one of readCh or writeCh should be non-null.
*
* @see #channelRead(ReadableByteChannel, ByteBuffer)
* @see #channelWrite(WritableByteChannel, ByteBuffer)
*/
private static int channelIO(ReadableByteChannel readCh,
WritableByteChannel writeCh,
ByteBuffer buf) throws IOException {
int originalLimit = buf.limit();
int initialRemaining = buf.remaining();
int ret = 0;
while (buf.remaining() > 0) {
try {
int ioSize = Math.min(buf.remaining(), NIO_BUFFER_LIMIT);
buf.limit(buf.position() + ioSize);
ret = (readCh == null) ? writeCh.write(buf) : readCh.read(buf);
if (ret < ioSize) {
break;
}
} finally {
buf.limit(originalLimit);
}
}
int nBytes = initialRemaining - buf.remaining();
return (nBytes > 0) ? nBytes : ret;
}
}