org.acplt.oncrpc.OncRpcUdpClient Maven / Gradle / Ivy
Show all versions of remotetea-oncrpc Show documentation
/*
* $Header: /home/harald/repos/remotetea.sf.net/remotetea/src/org/acplt/oncrpc/OncRpcUdpClient.java,v 1.7 2009/02/25 19:20:40 haraldalbrecht Exp $
*
* Copyright (c) 1999, 2000
* Lehrstuhl fuer Prozessleittechnik (PLT), RWTH Aachen
* D-52064 Aachen, Germany.
* All rights reserved.
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this program (see the file LICENSE.txt for more
* details); if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
package org.acplt.oncrpc;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.InetAddress;
import java.net.DatagramSocket;
/**
* ONC/RPC client which communicates with ONC/RPC servers over the network
* using the datagram-oriented protocol UDP/IP.
*
* @version $Revision: 1.7 $ $Date: 2009/02/25 19:20:40 $ $State: Exp $ $Locker: $
* @author Harald Albrecht
*/
public class OncRpcUdpClient extends OncRpcClient {
/**
* Constructs a new OncRpcUdpClient object, which connects
* to the ONC/RPC server at host for calling remote procedures
* of the given { program, version }.
*
* Note that the construction of an OncRpcUdpProtocolClient
* object will result in communication with the portmap process at
* host if port is 0.
*
* @param host The host where the ONC/RPC server resides.
* @param program Program number of the ONC/RPC server to call.
* @param version Program version number.
* @param port The port number where the ONC/RPC server can be contacted.
* If 0, then the OncRpcUdpClient object will
* ask the portmapper at host for the port number.
*
* @throws OncRpcException if an ONC/RPC error occurs.
* @throws IOException if an I/O error occurs.
*/
public OncRpcUdpClient(InetAddress host,
int program, int version,
int port)
throws OncRpcException, IOException {
this(host, program, version, port, 8192);
}
/**
* Constructs a new OncRpcUdpClient object, which connects
* to the ONC/RPC server at host for calling remote procedures
* of the given { program, version }.
*
*
Note that the construction of an OncRpcUdpProtocolClient
* object will result in communication with the portmap process at
* host if port is 0.
*
* @param host The host where the ONC/RPC server resides.
* @param program Program number of the ONC/RPC server to call.
* @param version Program version number.
* @param port The port number where the ONC/RPC server can be contacted.
* If 0, then the OncRpcUdpClient object will
* ask the portmapper at host for the port number.
* @param bufferSize The buffer size used for sending and receiving UDP
* datagrams.
*
* @throws OncRpcException if an ONC/RPC error occurs.
* @throws IOException if an I/O error occurs.
*/
public OncRpcUdpClient(InetAddress host,
int program, int version,
int port,
int bufferSize)
throws OncRpcException, IOException {
//
// Construct the inherited part of our object. This will also try to
// lookup the port of the desired ONC/RPC server, if no port number
// was specified (port = 0).
//
super(host, program, version, port, OncRpcProtocols.ONCRPC_UDP);
//
// Let the host operating system choose which port (and network
// interface) to use. Then set the buffer sizes for sending and
// receiving UDP datagrams. Finally set the destination of packets.
//
if ( bufferSize < 1024 ) {
bufferSize = 1024;
}
socket = new DatagramSocket();
socketHelper = new OncRpcUdpSocketHelper(socket);
if ( socketHelper.getSendBufferSize() < bufferSize ) {
socketHelper.setSendBufferSize(bufferSize);
}
if ( socketHelper.getReceiveBufferSize() < bufferSize ) {
socketHelper.setReceiveBufferSize(bufferSize);
}
//
// Note: we don't do a
// socket.connect(host, this.port);
// here anymore. XdrUdpEncodingStream long since then supported
// specifying the destination of an ONC/RPC UDP packet when
// start serialization. In addition, connecting a UDP socket disables
// the socket's ability to receive broadcasts. Without connecting you
// can send an ONC/RPC call to the broadcast address of the network
// and receive multiple replies.
//
// Create the necessary encoding and decoding streams, so we can
// communicate at all.
//
sendingXdr = new XdrUdpEncodingStream(socket, bufferSize);
receivingXdr = new XdrUdpDecodingStream(socket, bufferSize);
}
/**
* Close the connection to an ONC/RPC server and free all network-related
* resources. Well -- at least hope, that the Java VM will sometimes free
* some resources. Sigh.
*
* @throws OncRpcException if an ONC/RPC error occurs.
*/
public void close()
throws OncRpcException {
if ( socket != null ) {
socket.close();
socket = null;
}
if ( sendingXdr != null ) {
try {
sendingXdr.close();
} catch ( IOException e ) {
}
sendingXdr = null;
}
if ( receivingXdr != null ) {
try {
receivingXdr.close();
} catch ( IOException e ) {
}
receivingXdr = null;
}
}
/**
* Calls a remote procedure on an ONC/RPC server.
*
*
The OncRpcUdpClient uses a similar timeout scheme as
* the genuine Sun C implementation of ONC/RPC: it starts with a timeout
* of one second when waiting for a reply. If no reply is received within
* this time frame, the client doubles the timeout, sends a new request
* and then waits again for a reply. In every case the client will wait
* no longer than the total timeout set through the
* {@link #setTimeout(int)} method.
*
* @param procedureNumber Procedure number of the procedure to call.
* @param versionNumber Protocol version number.
* @param params The parameters of the procedure to call, contained
* in an object which implements the {@link XdrAble} interface.
* @param result The object receiving the result of the procedure call.
*
* @throws OncRpcException if an ONC/RPC error occurs.
*/
public synchronized void call(int procedureNumber, int versionNumber,
XdrAble params, XdrAble result)
throws OncRpcException {
Refresh:
for ( int refreshesLeft = 1; refreshesLeft >= 0;
--refreshesLeft ) {
//
// First, build the ONC/RPC call header. Then put the sending
// stream into a known state and encode the parameters to be
// sent. Finally tell the encoding stream to send all its data
// to the server. Then wait for an answer, receive it and decode
// it. So that's the bottom line of what we do right here.
//
nextXid();
//
// We only create our request message once and reuse it in case
// retransmission should be necessary -- with the exception being
// credential refresh. In this case we need to create a new
// request message.
//
OncRpcClientCallMessage callHeader =
new OncRpcClientCallMessage(xid,
program, versionNumber,
procedureNumber,
auth);
OncRpcClientReplyMessage replyHeader =
new OncRpcClientReplyMessage(auth);
long stopTime = System.currentTimeMillis() + timeout;
int resendTimeout = retransmissionTimeout;
//
// Now enter the great loop where we send calls out to the server
// and then sit there waiting for a reply. If none comes, we first
// resend our call after one second, then two seconds, four seconds,
// and so on, until we have reached the timeout for the call in total.
// Note that this setting only applies if exponential back-off
// retransmission has been selected. Per default we do not retransmit
// any more, in order to be in line with the SUNRPC implementations.
//
do {
try {
//
// Send call message to server. Remember that we've already
// "connected" the datagram socket, so java.net knows whom
// to send the datagram packets.
//
sendingXdr.beginEncoding(host, port);
callHeader.xdrEncode(sendingXdr);
params.xdrEncode(sendingXdr);
sendingXdr.endEncoding();
} catch ( IOException e ) {
throw(new OncRpcException(OncRpcException.RPC_CANTSEND,
e.getLocalizedMessage()));
}
//
// Receive reply message from server -- at least try to do so...
// In case of batched calls we don't need no stinkin' answer, so
// we can do other, more interesting things.
//
if ( timeout == 0 ) {
return;
}
//
// Wait for an answer to arrive...
//
for ( ;; ) {
try {
int currentTimeout = (int)(stopTime - System.currentTimeMillis());
if ( currentTimeout > resendTimeout ) {
currentTimeout = resendTimeout;
} else if ( currentTimeout < 1 ) {
//
// as setSoTimeout interprets a timeout of zero as
// infinite (?�$@%&!!!) we need to ensure that we
// have a finite timeout, albeit maybe an infinitesimal
// finite one.
currentTimeout = 1;
}
socket.setSoTimeout(currentTimeout);
receivingXdr.beginDecoding();
//
// FIX: do not check for reply address any longer as this
// check causes problems with valid clustering usecases.
//
//# Only accept incomming reply if it comes from the same
//# address we've sent the ONC/RPC call to. Otherwise throw
//# away the datagram packet containing the reply and start
//# over again, waiting for the next reply to arrive.
//
// if ( host.equals(receivingXdr.getSenderAddress()) ) {
//
// First, pull off the reply message header of the
// XDR stream. In case we also received a verifier
// from the server and this verifier was invalid, broken
// or tampered with, we will get an
// OncRpcAuthenticationException right here, which will
// propagate up to the caller. If the server reported
// an authentication problem itself, then this will
// be handled as any other rejected ONC/RPC call.
//
try {
replyHeader.xdrDecode(receivingXdr);
} catch ( OncRpcException e ) {
//
// ** SF bug #1262106 **
//
// We ran into some sort of trouble. Usually this will have
// been a buffer underflow. Whatever, end the decoding process
// and ensure this way that the next call has a chance to start
// from a clean state.
//
receivingXdr.endDecoding();
throw(e);
}
//
// Only deserialize the result, if the reply matches the call
// and if the reply signals a successful call. In case of an
// unsuccessful call (which mathes our call nevertheless) throw
// an exception.
//
if ( replyHeader.messageId == callHeader.messageId ) {
if ( !replyHeader.successfullyAccepted() ) {
receivingXdr.endDecoding();
//
// Check whether there was an authentication
// problem. In this case first try to refresh the
// credentials.
//
if ( (refreshesLeft > 0)
&& (replyHeader.replyStatus
== OncRpcReplyStatus.ONCRPC_MSG_DENIED)
&& (replyHeader.rejectStatus
== OncRpcRejectStatus.ONCRPC_AUTH_ERROR)
&& (auth != null)
&& auth.canRefreshCred() ) {
//
// Think about using a TAB size of four ;)
//
// Another instance of "CONTINUE considered
// useful"...
//
continue Refresh;
}
//
// Nope. No chance. This gets tough.
//
throw(replyHeader.newException());
}
//
// The reply header is okay and the call had been
// accepted by the ONC/RPC server, so we can now
// proceed to decode the outcome of the RPC.
//
try {
result.xdrDecode(receivingXdr);
} catch ( OncRpcException e ) {
//
// ** SF bug #1262106 **
//
// We ran into some sort of trouble. Usually this will have
// been a buffer underflow. Whatever, end the decoding process
// and ensure this way that the next call has a chance to start
// from a clean state.
//
receivingXdr.endDecoding();
throw(e);
}
//
// Free pending resources of buffer and exit the call loop,
// returning the reply to the caller through the result
// object.
//
receivingXdr.endDecoding();
return;
} else {
//
// The message id did no match -- probably some
// old UDP datagram which just popped up from the
// middle of the Internet.
//
// Yet another case of "CONTINUE considered not
// harmful"...
//
// [Nothing to do here, just wait for the next datagram]
}
// } else {
//
// FIX: This part has become unnecessary as we
// don't check the sender address for responses
// any longer.
//
//# IP address of received UDP datagram is not the same
//# as the IP address of the ONC/RPC server.
//#
//# [Nothing to do here, just wait for the next datagram]
// }
} catch ( InterruptedIOException e ) {
//
// Note that we only catch timeouts here, but no other
// exceptions. Those others will go up further until someone
// catches them. The timeouts are caught, so they can do no
// damage but instead we start another round of sending a
// request and waiting for a reply. Reminds me of NASA and
// their "Mars Polar Lander"...
//
// Note that we need to leave the inner waiting loop here,
// as we might need to resend the (lost) RPC request
// datagram.
//
break;
} catch ( IOException e ) {
//
// Argh. Trouble with the transport. Seems like we can't
// receive data. Gosh. Go away!
//
try {
receivingXdr.endDecoding(); // skip UDP record
} catch ( IOException ioe ) {
}
throw(new OncRpcException(OncRpcException.RPC_CANTRECV,
e.getLocalizedMessage()));
} catch ( OncRpcException e ) {
//
// Ooops. An ONC/RPC exception. Let us rethrow this one,
// as we won't have nothin' to do with it...
//
try {
receivingXdr.endDecoding(); // skip UDP record
} catch ( IOException ioe ) {
}
//
// Well, in case we got not a *reply* RPC message back,
// we keep listening for messages.
//
if ( e.getReason() != OncRpcException.RPC_WRONGMESSAGE ) {
throw(e);
}
}
//
// We can not make use of the reply we just received, so
// we need to dump it.
//
// This should raise no exceptions, when skipping the UDP
// record. So if one is raised, we will rethrow an ONC/RPC
// exception instead.
//
try {
receivingXdr.endDecoding();
} catch ( IOException e ) {
throw(new OncRpcException(OncRpcException.RPC_CANTRECV,
e.getLocalizedMessage()));
}
}
//
// We only reach this code part beyond the inner waiting
// loop if we run in a timeout and might need to retransmit
//
// According to the retransmission strategy choosen, update the
// current retransmission (resending) timeout.
//
if ( retransmissionMode == OncRpcUdpRetransmissionMode.EXPONENTIAL ) {
resendTimeout *= 2;
}
} while ( System.currentTimeMillis() < stopTime );
//
// That's it -- this shity server does not talk to us. Now, due to
// the indecent language used in the previous sentence, this software
// can not be exported any longer to some countries of the world.
// But this is surely not my problem, but rather theirs. So go away
// and hide yourself in the dark with all your zombies (or maybe
// kangaroos).
//
throw(new OncRpcTimeoutException());
} // for ( refreshesLeft )
}
/**
* Broadcast a remote procedure call to several ONC/RPC servers. For this
* you'll need to specify either a multicast address or the subnet's
* broadcast address when creating a OncRpcUdpClient. For
* every reply received, an event containing the reply is sent to the
* OncRpcBroadcastListener listener, which is the last
* parameter to the this method.
*
*
In contrast to the {@link #call(int, XdrAble, XdrAble)} method,
* broadcastCall will only send the ONC/RPC call once. It
* will then wait for answers until the timeout as set by
* {@link #setTimeout(int)} expires without resending the reply.
*
*
Note that you might experience unwanted results when using
* authentication types other than {@link OncRpcClientAuthNone}, causing
* messed up authentication protocol handling objects. This depends on
* the type of authentication used. For AUTH_UNIX nothing
* bad happens as long as none of the servers replies with a shorthand
* verifier. If it does, then this shorthand will be used on all subsequent
* ONC/RPC calls, something you probably do not want at all.
*
* @param procedureNumber Procedure number of the procedure to call.
* @param params The parameters of the procedure to call, contained
* in an object which implements the {@link XdrAble} interface.
* @param result The object receiving the result of the procedure call.
* Note that this object is reused to deserialize all incomming replies
* one after another.
* @param listener Listener which will get an {@link OncRpcBroadcastEvent}
* for every reply received.
*
* @throws OncRpcException if an ONC/RPC error occurs.
*/
public synchronized void broadcastCall(int procedureNumber,
XdrAble params, XdrAble result,
OncRpcBroadcastListener listener)
throws OncRpcException {
//
// First, build the ONC/RPC call header. Then put the sending
// stream into a known state and encode the parameters to be
// sent. Finally tell the encoding stream to broadcast all its data.
// Then wait for answers, receive and decode them one at a time.
//
nextXid();
OncRpcClientCallMessage callHeader =
new OncRpcClientCallMessage(xid,
program, version, procedureNumber,
auth);
OncRpcClientReplyMessage replyHeader =
new OncRpcClientReplyMessage(auth);
//
// Broadcast the call. Note that we send the call only once and will
// never resend it.
//
try {
//
// Send call message to server. Remember that we've already
// "connected" the datagram socket, so java.net knows whom
// to send the datagram packets.
//
sendingXdr.beginEncoding(host, port);
callHeader.xdrEncode(sendingXdr);
params.xdrEncode(sendingXdr);
sendingXdr.endEncoding();
} catch ( IOException e ) {
throw(new OncRpcException(OncRpcException.RPC_CANTSEND,
e.getLocalizedMessage()));
}
//
// Now enter the great loop where sit waiting for replies to our
// broadcast call to come in. In every case, we wait until the
// (total) timeout expires.
//
long stopTime = System.currentTimeMillis() + timeout;
do {
try {
//
// Calculate timeout until the total timeout is reached, so
// we can try to meet the overall deadline.
//
int currentTimeout = (int)(stopTime - System.currentTimeMillis());
if ( currentTimeout < 0 ) {
currentTimeout = 0;
}
socket.setSoTimeout(currentTimeout);
//
// Then wait for datagrams to arrive...
//
receivingXdr.beginDecoding();
replyHeader.xdrDecode(receivingXdr);
//
// Only deserialize the result, if the reply matches the call
// and if the reply signals a successful call. In case of an
// unsuccessful call (which mathes our call nevertheless) throw
// an exception.
//
if ( replyHeader.messageId == callHeader.messageId ) {
if ( !replyHeader.successfullyAccepted() ) {
//
// We got a notification of a rejected call. We silently
// ignore such replies and continue listening for other
// replies.
//
receivingXdr.endDecoding();
/* fall through to time check */
}
result.xdrDecode(receivingXdr);
//
// Notify a potential listener of the reply.
//
if ( listener != null ) {
OncRpcBroadcastEvent evt = new OncRpcBroadcastEvent(
this,
receivingXdr.getSenderAddress(),
procedureNumber, params, result);
listener.replyReceived(evt);
}
//
// Free pending resources of buffer and exit the call loop,
// returning the reply to the caller through the result
// object.
//
receivingXdr.endDecoding();
/* fall through to time check */
} else {
//
// This should raise no exceptions, when skipping the UDP
// record. So if one is raised, we will rethrow an ONC/RPC
// exception instead.
//
try {
receivingXdr.endDecoding();
} catch ( IOException e ) {
throw(new OncRpcException(OncRpcException.RPC_CANTRECV,
e.getLocalizedMessage()));
}
/* fall through to time check */
}
} catch ( InterruptedIOException e ) {
//
// Note that we only catch timeouts here, but no other
// exceptions. Those others will go up further until someone
// catches them. If we get the timeout we know that it
// could be time to leave the stage and so we fall through
// to the total timeout check.
//
/* fall through to time check */
} catch ( IOException e ) {
//
// Argh. Trouble with the transport. Seems like we can't
// receive data. Gosh. Go away!
//
throw(new OncRpcException(OncRpcException.RPC_CANTRECV,
e.getLocalizedMessage()));
}
} while ( System.currentTimeMillis() < stopTime );
return;
}
/**
* Set the {@link OncRpcUdpRetransmissionMode retransmission mode} for
* lost remote procedure calls. The default retransmission mode is
* {@link OncRpcUdpRetransmissionMode#FIXED}.
*
* @param mode Retransmission mode (either fixed or exponential).
*/
public void setRetransmissionMode(int mode) {
retransmissionMode = mode;
}
/**
* Retrieve the current
* {@link OncRpcUdpRetransmissionMode retransmission mode} set for
* retransmission of lost ONC/RPC calls.
*
* @return Current retransmission mode.
*/
public int getRetransmissionMode() {
return retransmissionMode;
}
/**
* Set the retransmission timout for remote procedure calls to wait for
* an answer from the ONC/RPC server before resending the call. The
* default retransmission timeout is the 30 seconds. The retransmission
* timeout must be > 0. To disable retransmission of lost calls, set
* the retransmission timeout to be the same value as the timeout.
*
* @param milliseconds Timeout in milliseconds. A timeout of zero indicates
* batched calls.
*/
public void setRetransmissionTimeout(int milliseconds) {
if ( milliseconds <= 0 ) {
throw(new IllegalArgumentException("timeouts must be positive."));
}
retransmissionTimeout = milliseconds;
}
/**
* Retrieve the current retransmission timeout set for remote procedure
* calls.
*
* @return Current retransmission timeout.
*/
public int getRetransmissionTimeout() {
return retransmissionTimeout;
}
/**
* Set the character encoding for (de-)serializing strings.
*
* @param characterEncoding the encoding to use for (de-)serializing strings.
* If null, the system's default encoding is to be used.
*/
public void setCharacterEncoding(String characterEncoding) {
receivingXdr.setCharacterEncoding(characterEncoding);
sendingXdr.setCharacterEncoding(characterEncoding);
}
/**
* Get the character encoding for (de-)serializing strings.
*
* @return the encoding currently used for (de-)serializing strings.
* If null, then the system's default encoding is used.
*/
public String getCharacterEncoding() {
return receivingXdr.getCharacterEncoding();
}
/**
* UDP socket used for datagram-based communication with an ONC/RPC
* server.
*/
private DatagramSocket socket;
/**
* Socket helper object supplying missing methods for JDK 1.1
* backwards compatibility. So much for compile once, does not run
* everywhere.
*/
private OncRpcUdpSocketHelper socketHelper;
/**
* XDR encoding stream used for sending requests via UDP/IP to an ONC/RPC
* server.
*/
protected XdrUdpEncodingStream sendingXdr;
/**
* XDR decoding stream used when receiving replies via UDP/IP from an
* ONC/RPC server.
*/
protected XdrUdpDecodingStream receivingXdr;
/**
* Retransmission timeout used for resending ONC/RPC calls when an ONC/RPC
* server does not answer fast enough. The default retransmission timeout
* is identical to the overall timeout for ONC/RPC calls (thus UDP/IP-based
* clients will not retransmit lost calls).
*
* @see OncRpcUdpClient#retransmissionMode
* @see OncRpcClient#setTimeout
*/
protected int retransmissionTimeout = super.timeout;
/**
* Retransmission mode used when resending ONC/RPC calls. Default mode is
* {@link OncRpcUdpRetransmissionMode#FIXED fixed timeout mode}.
*
* @see OncRpcUdpRetransmissionMode
*/
protected int retransmissionMode = OncRpcUdpRetransmissionMode.FIXED;
}
// End of OncRpcUdpClient.java