/*
* Copyright 2013 Google Inc.
*
* Licensed 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 com.google.devcoin.protocols.channels;
import com.google.devcoin.core.*;
import com.google.devcoin.utils.Threading;
import com.google.common.annotations.VisibleForTesting;
import com.google.protobuf.ByteString;
import net.jcip.annotations.GuardedBy;
import java.math.BigInteger;
import java.util.*;
import java.util.concurrent.locks.ReentrantLock;
import static com.google.common.base.Preconditions.*;
/**
* Keeps track of a set of {@link StoredServerChannel}s and expires them 2 hours before their refund transactions
* unlock.
*/
public class StoredPaymentChannelServerStates implements WalletExtension {
static final String EXTENSION_ID = StoredPaymentChannelServerStates.class.getName();
@GuardedBy("lock") @VisibleForTesting final Map<Sha256Hash, StoredServerChannel> mapChannels = new HashMap<Sha256Hash, StoredServerChannel>();
private final Wallet wallet;
private final TransactionBroadcaster broadcaster;
private final Timer channelTimeoutHandler = new Timer(true);
private final ReentrantLock lock = Threading.lock("StoredPaymentChannelServerStates");
/**
* The offset between the refund transaction's lock time and the time channels will be automatically closed.
* This defines a window during which we must get the last payment transaction verified, ie it should allow time for
* network propagation and for the payment transaction to be included in a block. Note that the channel expire time
* is measured in terms of our local clock, and the refund transaction's lock time is measured in terms of Bitcoin
* block header timestamps, which are allowed to drift up to two hours in the future, as measured by relaying nodes.
*/
public static final long CHANNEL_EXPIRE_OFFSET = -2*60*60;
/**
* Creates a new PaymentChannelServerStateManager and associates it with the given {@link Wallet} and
* {@link TransactionBroadcaster} which are used to complete and announce payment transactions.
*/
public StoredPaymentChannelServerStates(Wallet wallet, TransactionBroadcaster broadcaster) {
this.wallet = checkNotNull(wallet);
this.broadcaster = checkNotNull(broadcaster);
}
/**
* <p>Closes the given channel using {@link ServerConnectionEventHandler#closeChannel()} and
* {@link PaymentChannelServerState#close()} to notify any connected client of channel closure and to complete and
* broadcast the latest payment transaction.</p>
*
* <p>Removes the given channel from this set of {@link StoredServerChannel}s and notifies the wallet of a change to
* this wallet extension.</p>
*/
public void closeChannel(StoredServerChannel channel) {
lock.lock();
try {
if (mapChannels.remove(channel.contract.getHash()) == null)
return;
} finally {
lock.unlock();
}
synchronized (channel) {
channel.closeConnectedHandler();
try {
//TODO add event listener to PaymentChannelServerStateManager
channel.getOrCreateState(wallet, broadcaster).close();
} catch (ValueOutOfRangeException e) {
e.printStackTrace();
} catch (VerificationException e) {
e.printStackTrace();
}
channel.state = null;
}
wallet.addOrUpdateExtension(this);
}
/**
* Gets the {@link StoredServerChannel} with the given channel id (ie contract transaction hash).
*/
public StoredServerChannel getChannel(Sha256Hash id) {
lock.lock();
try {
return mapChannels.get(id);
} finally {
lock.unlock();
}
}
/**
* <p>Puts the given channel in the channels map and automatically closes it 2 hours before its refund transaction
* becomes spendable.</p>
*
* <p>Because there must be only one, canonical {@link StoredServerChannel} per channel, this method throws if the
* channel is already present in the set of channels.</p>
*/
public void putChannel(final StoredServerChannel channel) {
lock.lock();
try {
checkArgument(mapChannels.put(channel.contract.getHash(), checkNotNull(channel)) == null);
channelTimeoutHandler.schedule(new TimerTask() {
@Override
public void run() {
closeChannel(channel);
}
// Add the difference between real time and Utils.now() so that test-cases can use a mock clock.
}, new Date((channel.refundTransactionUnlockTimeSecs + CHANNEL_EXPIRE_OFFSET)*1000L
+ (System.currentTimeMillis() - Utils.now().getTime())));
} finally {
lock.unlock();
}
}
@Override
public String getWalletExtensionID() {
return EXTENSION_ID;
}
@Override
public boolean isWalletExtensionMandatory() {
return false;
}
@Override
public byte[] serializeWalletExtension() {
lock.lock();
try {
ServerState.StoredServerPaymentChannels.Builder builder = ServerState.StoredServerPaymentChannels.newBuilder();
for (StoredServerChannel channel : mapChannels.values()) {
// First a few asserts to make sure things won't break
checkState(channel.bestValueToMe.compareTo(BigInteger.ZERO) >= 0 && channel.bestValueToMe.compareTo(NetworkParameters.MAX_MONEY) < 0);
checkState(channel.refundTransactionUnlockTimeSecs > 0);
checkNotNull(channel.myKey.getPrivKeyBytes());
ServerState.StoredServerPaymentChannel.Builder channelBuilder = ServerState.StoredServerPaymentChannel.newBuilder()
.setBestValueToMe(channel.bestValueToMe.longValue())
.setRefundTransactionUnlockTimeSecs(channel.refundTransactionUnlockTimeSecs)
.setContractTransaction(ByteString.copyFrom(channel.contract.bitcoinSerialize()))
.setClientOutput(ByteString.copyFrom(channel.clientOutput.bitcoinSerialize()))
.setMyKey(ByteString.copyFrom(channel.myKey.getPrivKeyBytes()));
if (channel.bestValueSignature != null)
channelBuilder.setBestValueSignature(ByteString.copyFrom(channel.bestValueSignature));
builder.addChannels(channelBuilder);
}
return builder.build().toByteArray();
} finally {
lock.unlock();
}
}
@Override
public void deserializeWalletExtension(Wallet containingWallet, byte[] data) throws Exception {
lock.lock();
try {
checkArgument(containingWallet == wallet);
ServerState.StoredServerPaymentChannels states = ServerState.StoredServerPaymentChannels.parseFrom(data);
NetworkParameters params = containingWallet.getParams();
for (ServerState.StoredServerPaymentChannel storedState : states.getChannelsList()) {
StoredServerChannel channel = new StoredServerChannel(null,
new Transaction(params, storedState.getContractTransaction().toByteArray()),
new TransactionOutput(params, null, storedState.getClientOutput().toByteArray(), 0),
storedState.getRefundTransactionUnlockTimeSecs(),
new ECKey(storedState.getMyKey().toByteArray(), null),
BigInteger.valueOf(storedState.getBestValueToMe()),
storedState.hasBestValueSignature() ? storedState.getBestValueSignature().toByteArray() : null);
putChannel(channel);
}
} finally {
lock.unlock();
}
}
@Override
public String toString() {
lock.lock();
try {
StringBuilder buf = new StringBuilder();
for (StoredServerChannel stored : mapChannels.values()) {
buf.append(stored);
}
return buf.toString();
} finally {
lock.unlock();
}
}
}