path: root/cpp/src/Ice/Connection.cpp

// **********************************************************************
//
// Copyright (c) 2001
// Mutable Realms, Inc.
// Huntsville, AL, USA
//
// All Rights Reserved
//
// **********************************************************************

#include <Ice/Connection.h>
#include <Ice/Instance.h>
#include <Ice/LoggerUtil.h>
#include <Ice/Properties.h>
#include <Ice/TraceUtil.h>
#include <Ice/DefaultsAndOverrides.h>
#include <Ice/Transceiver.h>
#include <Ice/ThreadPool.h>
#include <Ice/ObjectAdapter.h>
#include <Ice/Endpoint.h>
#include <Ice/Outgoing.h>
#include <Ice/Incoming.h>
#include <Ice/LocalException.h>
#include <Ice/Protocol.h>
#include <bzlib.h>

using namespace std;
using namespace Ice;
using namespace IceInternal;

void IceInternal::incRef(Connection* p) { p->__incRef(); }
void IceInternal::decRef(Connection* p) { p->__decRef(); }

bool
IceInternal::Connection::destroyed() const
{
    IceUtil::RecMutex::Lock sync(*this);
    return _state >= StateClosing;
}

void
IceInternal::Connection::validate()
{
    IceUtil::RecMutex::Lock sync(*this);

    if(_endpoint->datagram())
    {
	//
	// Datagram connections are always implicitly validated.
	//
	return;
    }

    try
    {
	if(_adapter)
	{
	    //
	    // Incoming connections play the active role with respect to
	    // connection validation.
	    //
	    BasicStream os(_instance);
	    os.write(protocolVersion);
	    os.write(encodingVersion);
	    os.write(validateConnectionMsg);
	    os.write(headerSize); // Message size.
	    os.i = os.b.begin();
	    traceHeader("sending validate connection", os, _logger, _traceLevels);
	    _transceiver->write(os, _endpoint->timeout());
	}
	else
	{
	    //
	    // Outgoing connection play the passive role with respect to
	    // connection validation.
	    //
	    BasicStream is(_instance);
	    is.b.resize(headerSize);
	    is.i = is.b.begin();
	    _transceiver->read(is, _endpoint->timeout());
	    assert(is.i == is.b.end());
	    int pos = is.i - is.b.begin();
	    assert(pos >= headerSize);
	    is.i = is.b.begin();
	    Byte protVer;
	    is.read(protVer);
	    if(protVer != protocolVersion)
	    {
		throw UnsupportedProtocolException(__FILE__, __LINE__);
	    }
	    Byte encVer;
	    is.read(encVer);
	    if(encVer != encodingVersion)
	    {
		throw UnsupportedEncodingException(__FILE__, __LINE__);
	    }
	    Byte messageType;
	    is.read(messageType);
	    if(messageType != validateConnectionMsg)
	    {
		throw ConnectionNotValidatedException(__FILE__, __LINE__);
	    }
	    Int size;
	    is.read(size);
	    if(size != headerSize)
	    {
		throw IllegalMessageSizeException(__FILE__, __LINE__);
	    }
	    traceHeader("received validate connection", is, _logger, _traceLevels);
	}
    }
    catch(const LocalException& ex)
    {
	setState(StateClosed, ex);
	assert(_exception.get());
	_exception->ice_throw();
    }
}

void
IceInternal::Connection::hold()
{
    IceUtil::RecMutex::Lock sync(*this);
    setState(StateHolding);
}

void
IceInternal::Connection::activate()
{
    IceUtil::RecMutex::Lock sync(*this);
    setState(StateActive);
}

void
IceInternal::Connection::incUsageCount()
{
    IceUtil::RecMutex::Lock sync(*this);
    assert(_usageCount >= 0);
    ++_usageCount;
}

void
IceInternal::Connection::decUsageCount()
{
    IceUtil::RecMutex::Lock sync(*this);
    assert(_usageCount > 0);
    --_usageCount;
    if(_usageCount == 0 && !_adapter)
    {
	assert(_requests.empty());
	setState(StateClosing, CloseConnectionException(__FILE__, __LINE__));
    }
}

void
IceInternal::Connection::prepareRequest(Outgoing* out)
{
    BasicStream* os = out->os();
    os->write(protocolVersion);
    os->write(encodingVersion);
    os->write(requestMsg);
    os->write(Int(0)); // Message size (placeholder).
    os->write(Int(0)); // Request ID (placeholder).
}

void
IceInternal::Connection::sendRequest(Outgoing* out, bool oneway, bool comp)
{
    IceUtil::RecMutex::Lock sync(*this);

    if(_exception.get())
    {
	_exception->ice_throw();
    }
    assert(_state < StateClosing);

    Int requestId;

    try
    {
	BasicStream* os = out->os();
	
	//
	// Fill in the request ID.
	//
	if(!_endpoint->datagram() && !oneway)
	{
	    requestId = _nextRequestId++;
	    if(requestId <= 0)
	    {
		_nextRequestId = 1;
		requestId = _nextRequestId++;
	    }
	    const Byte* p;
	    p = reinterpret_cast<const Byte*>(&requestId);
	    copy(p, p + sizeof(Int), os->b.begin() + headerSize);
	}

	if(os->b.size() < 100) // Don't compress if message size is smaller than 100 bytes.
	{
	    comp = false;
	}
	else
	{
	    if(_defaultsAndOverrides->overrideComppress)
	    {
		comp = _defaultsAndOverrides->overrideComppressValue;
	    }
	}

	if(comp)
	{
	    //
	    // Change message type.
	    //
	    os->b[2] = compressedRequestMsg;

	    //
	    // Do compression.
	    //
	    BasicStream cstream(_instance);
	    compress(*os, cstream);
	    
	    //
	    // Send the request.
	    //
	    os->i = os->b.begin();
	    traceRequest("sending compressed request", *os, _logger, _traceLevels);
	    cstream.i = cstream.b.begin();
	    _transceiver->write(cstream, _endpoint->timeout());
	}
	else
	{
	    //
	    // No compression, just fill in the message size.
	    //
	    const Byte* p;
	    Int sz = os->b.size();
	    p = reinterpret_cast<const Byte*>(&sz);
	    copy(p, p + sizeof(Int), os->b.begin() + 3);

	    //
	    // Send the request.
	    //
	    os->i = os->b.begin();
	    traceRequest("sending request", *os, _logger, _traceLevels);
	    _transceiver->write(*os, _endpoint->timeout());
	}
    }
    catch(const LocalException& ex)
    {
	setState(StateClosed, ex);
	assert(_exception.get());
	_exception->ice_throw();
    }
    
    //
    // Only add to the request map if there was no exception, and if
    // the operation is not oneway.
    //
    if(!_endpoint->datagram() && !oneway)
    {
	_requestsHint = _requests.insert(_requests.end(), make_pair(requestId, out));
    }
}

void
IceInternal::Connection::prepareBatchRequest(Outgoing* out)
{
    lock();

    if(_exception.get())
    {
	unlock();
	_exception->ice_throw();
    }
    assert(_state < StateClosing);

    //
    // The Connection now belongs to `out', until finishBatchRequest()
    // is called.
    //

    if(_batchStream.b.empty())
    {
	_batchStream.write(protocolVersion);
	_batchStream.write(encodingVersion);
	_batchStream.write(requestBatchMsg);
	_batchStream.write(Int(0)); // Message size (placeholder).
    }

    //
    // Give the batch stream to `out', until finishBatchRequest() is
    // called.
    //
    _batchStream.swap(*out->os());
}

void
IceInternal::Connection::finishBatchRequest(Outgoing* out)
{
    if(_exception.get())
    {
	unlock();
	_exception->ice_throw();
    }
    assert(_state < StateClosing);

    _batchStream.swap(*out->os()); // Get the batch stream back.
    unlock(); // Give the Connection back.
}

void
IceInternal::Connection::abortBatchRequest()
{
    setState(StateClosed, AbortBatchRequestException(__FILE__, __LINE__));
    unlock(); // Give the Connection back.
}

void
IceInternal::Connection::flushBatchRequest(bool comp)
{
    IceUtil::RecMutex::Lock sync(*this);

    if(_exception.get())
    {
	_exception->ice_throw();
    }
    assert(_state < StateClosing);
    
    try
    {
	if(_batchStream.b.empty())
	{
	    return; // Nothing to send.
	}

	_batchStream.i = _batchStream.b.begin();
	
	if(_batchStream.b.size() < 100) // Don't compress if message size is smaller than 100 bytes.
	{
	    comp = false;
	}
	else
	{
	    if(_defaultsAndOverrides->overrideComppress)
	    {
		comp = _defaultsAndOverrides->overrideComppressValue;
	    }
	}

	if(comp)
	{
	    //
	    // Change message type.
	    //
	    _batchStream.b[2] = compressedRequestBatchMsg;

	    //
	    // Do compression.
	    //
	    BasicStream cstream(_instance);
	    compress(_batchStream, cstream);
	    
	    //
	    // Send the batch request.
	    //
	    _batchStream.i = _batchStream.b.begin();
	    traceBatchRequest("sending compressed batch request", _batchStream, _logger, _traceLevels);
	    cstream.i = cstream.b.begin();
	    _transceiver->write(cstream, _endpoint->timeout());
	}
	else
	{
	    //
	    // No compression, just fill in the message size.
	    //
	    const Byte* p;
	    Int sz = _batchStream.b.size();
	    p = reinterpret_cast<const Byte*>(&sz);
	    copy(p, p + sizeof(Int), _batchStream.b.begin() + 3);

	    //
	    // Send the batch request.
	    //
	    _batchStream.i = _batchStream.b.begin();
	    traceBatchRequest("sending batch request", _batchStream, _logger, _traceLevels);
	    _transceiver->write(_batchStream, _endpoint->timeout());
	}

	//
	// Reset _batchStream so that new batch messages can be sent.
	//
	BasicStream dummy(_instance);
	_batchStream.swap(dummy);
	assert(_batchStream.b.empty());
    }
    catch(const LocalException& ex)
    {
	setState(StateClosed, ex);
	assert(_exception.get());
	_exception->ice_throw();
    }
}

int
IceInternal::Connection::timeout() const
{
    // No mutex protection necessary, _endpoint is immutable.
    return _endpoint->timeout();
}

EndpointPtr
IceInternal::Connection::endpoint() const
{
    // No mutex protection necessary, _endpoint is immutable.
    return _endpoint;
}

void
IceInternal::Connection::setAdapter(const ObjectAdapterPtr& adapter)
{
    IceUtil::RecMutex::Lock sync(*this);

    //
    // We are registered with a thread pool in active and closing
    // mode. However, we only change subscription if we're in active
    // mode, and thus ignore closing mode here.
    //
    if(_state == StateActive)
    {
	if(adapter && !_adapter)
	{
	    //
	    // Client is now server.
	    //
	    unregisterWithPool();
	}
	
	if(!adapter && _adapter)
	{
	    //
	    // Server is now client.
	    //
	    unregisterWithPool();
	}
    }

    _adapter = adapter;
}

ObjectAdapterPtr
IceInternal::Connection::getAdapter() const
{
    IceUtil::RecMutex::Lock sync(*this);
    return _adapter;
}

bool
IceInternal::Connection::readable() const
{
    return true;
}

void
IceInternal::Connection::read(BasicStream& stream)
{
    _transceiver->read(stream, 0);
}

void
IceInternal::Connection::message(BasicStream& stream, const ThreadPoolPtr& threadPool)
{
    bool invoke = false;
    bool comp = false;
    bool batch = false;

    {
	IceUtil::RecMutex::Lock sync(*this);
	
	threadPool->promoteFollower();
	
	if(_state == StateClosed)
	{
	    IceUtil::ThreadControl::yield();
	    return;
	}

	Byte messageType;

	try
	{
	    assert(stream.i == stream.b.end());
	    stream.i = stream.b.begin() + 2;
	    stream.read(messageType);

	    //
	    // Uncompress if necessary.
	    //
	    if(messageType == compressedRequestMsg ||
	       messageType == compressedRequestBatchMsg ||
	       messageType == compressedReplyMsg)
	    {
		BasicStream ustream(_instance);
		uncompress(stream, ustream);
		stream.b.swap(ustream.b);
		comp = true;
	    }
	    
	    stream.i = stream.b.begin() + headerSize;
	    
	    switch(messageType)
	    {
		case requestMsg:
		{
		    if(_state == StateClosing)
		    {
			traceRequest("received request during closing\n"
				     "(ignored by server, client will retry)",
				     stream, _logger, _traceLevels);
		    }
		    else
		    {
			traceRequest("received request", stream, _logger, _traceLevels);
			invoke = true;
		    }
		    break;
		}
		
		case compressedRequestMsg:
		{
		    if(_state == StateClosing)
		    {
			traceRequest("received compressed request during closing\n"
				     "(ignored by server, client will retry)",
				     stream, _logger, _traceLevels);
		    }
		    else
		    {
			traceRequest("received compressed request", stream, _logger, _traceLevels);
			invoke = true;
		    }
		    break;
		}
		
		case requestBatchMsg:
		{
		    if(_state == StateClosing)
		    {
			traceBatchRequest("received batch request during closing\n"
					  "(ignored by server, client will retry)",
					  stream, _logger, _traceLevels);
		    }
		    else
		    {
			traceBatchRequest("received batch request", stream, _logger, _traceLevels);
			invoke = true;
			batch = true;
		    }
		    break;
		}
		
		case compressedRequestBatchMsg:
		{
		    if(_state == StateClosing)
		    {
			traceBatchRequest("received compressed batch request during closing\n"
					  "(ignored by server, client will retry)",
					  stream, _logger, _traceLevels);
		    }
		    else
		    {
			traceBatchRequest("received compressed batch request", stream, _logger, _traceLevels);
			invoke = true;
			batch = true;
		    }
		    break;
		}
		
		case replyMsg:
		case compressedReplyMsg:
		{
		    if(messageType == compressedReplyMsg)
		    {
			traceReply("received compressed reply", stream, _logger, _traceLevels);
		    }
		    else
		    {
			traceReply("received reply", stream, _logger, _traceLevels);
		    }

		    Int requestId;
		    stream.read(requestId);
		    
		    map<Int, Outgoing*>::iterator p = _requests.end();
		    
		    if(_requestsHint != _requests.end())
		    {
			if(_requestsHint->first == requestId)
			{
			    p = _requestsHint;
			}
		    }
		    
		    if(p == _requests.end())
		    {
			p = _requests.find(requestId);
		    }
		    
		    if(p == _requests.end())
		    {
			throw UnknownRequestIdException(__FILE__, __LINE__);
		    }

		    p->second->finished(stream);

		    if(p == _requestsHint)
		    {
			_requests.erase(p++);
			_requestsHint = p;
		    }
		    else
		    {
			_requests.erase(p);
		    }

		    break;
		}
		
		case validateConnectionMsg:
		{
		    traceHeader("received validate connection", stream, _logger, _traceLevels);
		    if(_warn)
		    {
			Warning out(_logger);
			out << "ignoring unexpected validate connection message:\n"
			    << _transceiver->toString();
		    }
		    break;
		}
		
		case closeConnectionMsg:
		{
		    traceHeader("received close connection", stream, _logger, _traceLevels);
		    if(_endpoint->datagram())
		    {
			if(_warn)
			{
			    Warning out(_logger);
			    out << "ignoring close connection message for datagram connection:\n"
				<< _transceiver->toString();
			}
		    }
		    else
		    {
			throw CloseConnectionException(__FILE__, __LINE__);
		    }
		    break;
		}
		
		default:
		{
		    traceHeader("received unknown message\n"
				"(invalid, closing connection)",
				stream, _logger, _traceLevels);
		    throw UnknownMessageException(__FILE__, __LINE__);
		    break;
		}
	    }
	}
	catch(const LocalException& ex)
	{
	    setState(StateClosed, ex);
	    return;
	}
    }

    //
    // Method invocation must be done outside the thread
    // synchronization, so that nested callbacks are possible.
    //
    if(invoke)
    {
	//
	// Prepare the invocation.
	//
	Incoming in(_instance, _adapter);
	BasicStream* is = in.is();
	stream.swap(*is);
	BasicStream* os = 0;

	try
	{
	    //
	    // Prepare the response if necessary.
	    //
	    if(!batch)
	    {
		Int requestId;
		is->read(requestId);
		if(!_endpoint->datagram() && requestId != 0) // 0 means oneway.
		{
		    ++_responseCount;
		    os = in.os();
		    os->write(protocolVersion);
		    os->write(encodingVersion);
		    os->write(replyMsg);
		    os->write(Int(0)); // Message size (placeholder).
		    os->write(requestId);
		}
	    }
	    
	    //
	    // Do the invocation, or multiple invocations for batch
	    // messages.
	    //
	    do
	    {
		in.invoke(os != 0);
	    }
	    while(batch && is->i < is->b.end());
	}
	catch(const LocalException& ex)
	{
	    IceUtil::RecMutex::Lock sync(*this);
	    setState(StateClosed, ex);
	    return;
	}
	
	//
	// Send a response if necessary.
	//
	if(os != 0)
	{
	    IceUtil::RecMutex::Lock sync(*this);
	    
	    try
	    {
		if(_state == StateClosed)
		{
		    return;
		}
		
		if(os->b.size() < 100) // Don't compress if message size is smaller than 100 bytes.
		{
		    comp = false;
		}
		else
		{
		    if(_defaultsAndOverrides->overrideComppress)
		    {
			comp = _defaultsAndOverrides->overrideComppressValue;
		    }
		}
		
		if(comp)
		{
		    //
		    // Change message type.
		    //
		    os->b[2] = compressedReplyMsg;
		    
		    //
		    // Do compression.
		    //
		    BasicStream cstream(_instance);
		    compress(*os, cstream);
		    
		    //
		    // Send the reply.
		    //
		    os->i = os->b.begin();
		    traceReply("sending compressed reply", *os, _logger, _traceLevels);
		    cstream.i = cstream.b.begin();
		    _transceiver->write(cstream, _endpoint->timeout());
		}
		else
		{
		    //
		    // No compression, just fill in the message size.
		    //
		    const Byte* p;
		    Int sz = os->b.size();
		    p = reinterpret_cast<const Byte*>(&sz);
		    copy(p, p + sizeof(Int), os->b.begin() + 3);
		    
		    //
		    // Send the reply.
		    //
		    os->i = os->b.begin();
		    traceReply("sending reply", *os, _logger, _traceLevels);
		    _transceiver->write(*os, _endpoint->timeout());
		}
		
		--_responseCount;
		
		if(_state == StateClosing && _responseCount == 0 && !_endpoint->datagram())
		{
		    closeConnection();
		}
	    }
	    catch(const LocalException& ex)
	    {
		setState(StateClosed, ex);
		return;
	    }
	}
    }
}

void
IceInternal::Connection::finished(const ThreadPoolPtr& threadPool)
{
    IceUtil::RecMutex::Lock sync(*this);

    threadPool->promoteFollower();

    if(_state == StateActive || _state == StateClosing)
    {
	registerWithPool();
    }
    else if(_state == StateClosed)
    {
	_transceiver->close();
    }
}

void
IceInternal::Connection::exception(const LocalException& ex)
{
    IceUtil::RecMutex::Lock sync(*this);
    setState(StateClosed, ex);
}

string
IceInternal::Connection::toString() const
{
    return _transceiver->toString();
}

IceInternal::Connection::Connection(const InstancePtr& instance,
				    const TransceiverPtr& transceiver,
				    const EndpointPtr& endpoint,
				    const ObjectAdapterPtr& adapter) :
    EventHandler(instance),
    _transceiver(transceiver),
    _endpoint(endpoint),
    _adapter(adapter),
    _logger(_instance->logger()),
    _traceLevels(_instance->traceLevels()),
    _defaultsAndOverrides(_instance->defaultsAndOverrides()),
    _warn(_instance->properties()->getPropertyAsInt("Ice.ConnectionWarnings") > 0),
    _nextRequestId(1),
    _requestsHint(_requests.end()),
    _batchStream(_instance),
    _responseCount(0),
    _usageCount(0),
    _state(StateHolding),
    _registeredWithPool(false)
{
}

IceInternal::Connection::~Connection()
{
    assert(_usageCount == 0);
    assert(_state == StateClosed);
}

void
IceInternal::Connection::destroy(DestructionReason reason)
{
    RecMutex::Lock sync(*this);

    switch(reason)
    {
	case ObjectAdapterDeactivated:
	{
	    setState(StateClosing, ObjectAdapterDeactivatedException(__FILE__, __LINE__));
	    break;
	}

	case CommunicatorDestroyed:
	{
	    setState(StateClosing, CommunicatorDestroyedException(__FILE__, __LINE__));
	    break;
	}
    }
}

void
IceInternal::Connection::setState(State state, const LocalException& ex)
{
    if(_state == state) // Don't switch twice.
    {
	return;
    }

    if(!_exception.get())
    {
	_exception = auto_ptr<LocalException>(dynamic_cast<LocalException*>(ex.ice_clone()));

	if(_warn)
	{
	    //
	    // Don't warn about certain expected exceptions.
	    //
	    if(!(dynamic_cast<const CloseConnectionException*>(_exception.get()) ||
		 dynamic_cast<const CommunicatorDestroyedException*>(_exception.get()) ||
		 dynamic_cast<const ObjectAdapterDeactivatedException*>(_exception.get()) ||
		 (dynamic_cast<const ConnectionLostException*>(_exception.get()) && _state == StateClosing)))
	    {
		Warning out(_logger);
		out << "connection exception:\n" << *_exception.get() << '\n' << _transceiver->toString();
	    }
	}
    }
    
    for(std::map< ::Ice::Int, Outgoing*>::iterator p = _requests.begin(); p != _requests.end(); ++p)
    {
	p->second->finished(*_exception.get());
    }
    _requests.clear();
    _requestsHint = _requests.end();

    setState(state);
}

void
IceInternal::Connection::setState(State state)
{
    //
    // We don't want to send close connection messages if the endpoint
    // only supports oneway transmission from client to server.
    //
    if(_endpoint->datagram() && state == StateClosing)
    {
	state = StateClosed;
    }

    if(_state == state) // Don't switch twice.
    {
	return;
    }
    
    switch(state)
    {
	case StateActive:
	{
	    if(_state != StateHolding) // Can only switch from holding to active.
	    {
		return;
	    }
	    registerWithPool();
	    break;
	}
	
	case StateHolding:
	{
	    if(_state != StateActive) // Can only switch from active to holding.
	    {
		return;
	    }
	    unregisterWithPool();
	    break;
	}

	case StateClosing:
	{
	    if(_state == StateClosed) // Can't change back from closed.
	    {
		return;
	    }
	    if(_state == StateHolding)
	    {
		//
		// We need to continue to read data in closing state.
		//
		registerWithPool();
	    }
	    break;
	}
	
	case StateClosed:
	{
	    if(_state == StateHolding)
	    {
		//
		// If we come from holding state, we first need to
		// register again before we unregister, so that
		// finished() is called correctly.
		//
		registerWithPool();
	    }
	    unregisterWithPool();
	    break;
	}
    }

    _state = state;

    if(_state == StateClosing && _responseCount == 0 && !_endpoint->datagram())
    {
	try
	{
	    closeConnection();
	}
	catch(const LocalException& ex)
	{
	    setState(StateClosed, ex);
	}
    }
}

void
IceInternal::Connection::closeConnection() const
{
    BasicStream os(_instance);
    os.write(protocolVersion);
    os.write(encodingVersion);
    os.write(closeConnectionMsg);
    os.write(headerSize); // Message size.
    os.i = os.b.begin();
    traceHeader("sending close connection", os, _logger, _traceLevels);
    _transceiver->write(os, _endpoint->timeout());

    //
    // A close connection is always followed by a connection shutdown.
    //
    _transceiver->shutdown();
}

void
IceInternal::Connection::registerWithPool()
{
    if(!_registeredWithPool)
    {
	if(_adapter)
	{
	    if(!_serverThreadPool) // Lazy initialization.
	    {
		const_cast<ThreadPoolPtr&>(_serverThreadPool) = _instance->serverThreadPool();
		assert(_serverThreadPool);
	    }
	    _serverThreadPool->_register(_transceiver->fd(), this);
	}
	else
	{
	    if(!_clientThreadPool) // Lazy initialization.
	    {
		const_cast<ThreadPoolPtr&>(_clientThreadPool) = _instance->clientThreadPool();
		assert(_clientThreadPool);
	    }
	    _clientThreadPool->_register(_transceiver->fd(), this);
	}

	_registeredWithPool = true;
    }
}

void
IceInternal::Connection::unregisterWithPool()
{
    if(_registeredWithPool)
    {
	if(_adapter)
	{
	    assert(_serverThreadPool);
	    _serverThreadPool->unregister(_transceiver->fd());
	}
	else
	{
	    assert(_clientThreadPool);
	    _clientThreadPool->unregister(_transceiver->fd());
	}

	_registeredWithPool = false;
    }
}

void
IceInternal::Connection::compress(BasicStream& uncompressed, BasicStream& compressed)
{
    const Byte* p;

    //
    // Compress the message body, but not the header.
    //
    unsigned int uncompressedLen = uncompressed.b.size() - headerSize;
    unsigned int compressedLen = static_cast<int>(uncompressedLen * 1.01 + 600);
    compressed.b.resize(headerSize + sizeof(Int) + compressedLen);
    int bzError = BZ2_bzBuffToBuffCompress(&compressed.b[0] + headerSize + sizeof(Int), &compressedLen,
					   &uncompressed.b[0] + headerSize, uncompressedLen,
					   1, 0, 0);
    if(bzError != BZ_OK)
    {
	throw CompressionException(__FILE__, __LINE__);
    }
    compressed.b.resize(headerSize + sizeof(Int) + compressedLen);
    
    //
    // Write the size of the compressed stream into the header of the
    // uncompressed stream. Since the header will be copied, this size
    // will also be in the header of the compressed stream.
    //
    Int compressedSize = compressed.b.size();
    p = reinterpret_cast<const Byte*>(&compressedSize);
    copy(p, p + sizeof(Int), uncompressed.b.begin() + 3);

    //
    // Add the size of the uncompressed stream before the message body
    // of the compressed stream.
    //
    Int uncompressedSize = uncompressed.b.size();
    p = reinterpret_cast<const Byte*>(&uncompressedSize);
    copy(p, p + sizeof(Int), compressed.b.begin() + headerSize);
    
    //
    // Copy the header from the uncompressed stream to the compressed one.
    //
    copy(uncompressed.b.begin(), uncompressed.b.begin() + headerSize, compressed.b.begin());
}

void
IceInternal::Connection::uncompress(BasicStream& compressed, BasicStream& uncompressed)
{
    Int uncompressedSize;
    compressed.i = compressed.b.begin() + headerSize;
    compressed.read(uncompressedSize);
    if(uncompressedSize <= headerSize)
    {
	throw IllegalMessageSizeException(__FILE__, __LINE__);
    }

    uncompressed.resize(uncompressedSize);
    unsigned int uncompressedLen = uncompressedSize - headerSize;
    unsigned int compressedLen = compressed.b.size() - headerSize - sizeof(Int);
    int bzError = BZ2_bzBuffToBuffDecompress(&uncompressed.b[0] + headerSize,
					     &uncompressedLen,
					     &compressed.b[0] + headerSize + sizeof(Int),
					     compressedLen,
					     0, 0);
    if(bzError != BZ_OK)
    {
	throw CompressionException(__FILE__, __LINE__);
    }

    copy(compressed.b.begin(), compressed.b.begin() + headerSize, uncompressed.b.begin());
}