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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cassandra.net;
import java.io.EOFException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Objects;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.io.compress.BufferType;
import org.apache.cassandra.io.util.DataInputBuffer;
import org.apache.cassandra.io.util.DataOutputBufferFixed;
import org.apache.cassandra.locator.InetAddressAndPort;
import org.apache.cassandra.utils.memory.BufferPools;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.apache.cassandra.locator.InetAddressAndPort.Serializer.inetAddressAndPortSerializer;
import static org.apache.cassandra.net.MessagingService.VERSION_40;
import static org.apache.cassandra.net.Message.validateLegacyProtocolMagic;
import static org.apache.cassandra.net.Crc.*;
import static org.apache.cassandra.net.OutboundConnectionSettings.*;
/**
* Messages for the handshake phase of the internode protocol.
*
* The modern handshake is composed of 2 messages: Initiate and Accept
*
* The legacy handshake is composed of 3 messages, the first being sent by the initiator of the connection. The other
* side then answer with the 2nd message. At that point, if a version mismatch is detected by the connection initiator,
* it will simply disconnect and reconnect with a more appropriate version. But if the version is acceptable, the connection
* initiator sends the third message of the protocol, after which it considers the connection ready.
*/
class HandshakeProtocol
{
static final long TIMEOUT_MILLIS = 3 * DatabaseDescriptor.getRpcTimeout(MILLISECONDS);
/**
* The initial message sent when a node creates a new connection to a remote peer. This message contains:
* 1) the {@link Message#PROTOCOL_MAGIC} number (4 bytes).
* 2) the connection flags (4 bytes), which encodes:
* - the version the initiator thinks should be used for the connection (in practice, either the initiator
* version if it's the first time we connect to that remote since startup, or the last version known for that
* peer otherwise).
* - the "mode" of the connection: whether it is for streaming or for messaging.
* - whether compression should be used or not (if it is, compression is enabled _after_ the last message of the
* handshake has been sent).
* 3) the connection initiator's broadcast address
* 4) a CRC protecting the message from corruption
*
* More precisely, connection flags:
*
* {@code
* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |C C C M C | REQUEST | MIN | MAX |
* |A A M O R | VERSION | SUPPORTED | SUPPORTED |
* |T T P D C | (DEPRECATED) | VERSION | VERSION |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* }
*
* CAT - QOS category, 2 bits: SMALL, LARGE, URGENT, or LEGACY (unset)
* CMP - compression enabled bit
* MOD - connection mode; if the bit is on, the connection is for streaming; if the bit is off, it is for inter-node messaging.
* CRC - crc enabled bit
* VERSION - {@link org.apache.cassandra.net.MessagingService#current_version}
*/
static class Initiate
{
/** Contains the PROTOCOL_MAGIC (int) and the flags (int). */
private static final int MIN_LENGTH = 8;
private static final int MAX_LENGTH = 12 + InetAddressAndPort.Serializer.MAXIMUM_SIZE;
// the messagingVersion bounds the sender will accept to initiate a connection;
// if the remote peer supports any, the newest supported version will be selected; otherwise the nearest supported version
final AcceptVersions acceptVersions;
final ConnectionType type;
final Framing framing;
final InetAddressAndPort from;
Initiate(AcceptVersions acceptVersions, ConnectionType type, Framing framing, InetAddressAndPort from)
{
this.acceptVersions = acceptVersions;
this.type = type;
this.framing = framing;
this.from = from;
}
private int encodeFlags()
{
int flags = 0;
if (type.isMessaging())
flags |= type.twoBitID();
if (type.isStreaming())
flags |= 1 << 3;
// framing id is split over 2nd and 4th bits, for backwards compatibility
flags |= ((framing.id & 1) << 2) | ((framing.id & 2) << 3);
flags |= (acceptVersions.min << 8); // legacy (pre40)
flags |= (acceptVersions.min << 16);
flags |= (acceptVersions.max << 24);
return flags;
}
ByteBuf encode()
{
ByteBuffer buffer = BufferPools.forNetworking().get(MAX_LENGTH, BufferType.OFF_HEAP);
try (DataOutputBufferFixed out = new DataOutputBufferFixed(buffer))
{
out.writeInt(Message.PROTOCOL_MAGIC);
out.writeInt(encodeFlags());
inetAddressAndPortSerializer.serialize(from, out, acceptVersions.min);
out.writeInt(computeCrc32(buffer, 0, buffer.position()));
buffer.flip();
return GlobalBufferPoolAllocator.wrap(buffer);
}
catch (IOException e)
{
throw new IllegalStateException(e);
}
}
static Initiate maybeDecode(ByteBuf buf) throws IOException
{
if (buf.readableBytes() < MIN_LENGTH)
return null;
ByteBuffer nio = buf.nioBuffer();
int start = nio.position();
try (DataInputBuffer in = new DataInputBuffer(nio, false))
{
validateLegacyProtocolMagic(in.readInt());
int flags = in.readInt();
// legacy pre40 messagingVersion flag
if (getBits(flags, 8, 8) < VERSION_40)
return null;
int minMessagingVersion = getBits(flags, 16, 8);
int maxMessagingVersion = getBits(flags, 24, 8);
// 5.0+ does not support pre40
if (maxMessagingVersion < MessagingService.VERSION_40)
return null;
int framingBits = getBits(flags, 2, 1) | (getBits(flags, 4, 1) << 1);
Framing framing = Framing.forId(framingBits);
boolean isStream = getBits(flags, 3, 1) == 1;
ConnectionType type = isStream
? ConnectionType.STREAMING
: ConnectionType.fromId(getBits(flags, 0, 2));
InetAddressAndPort from = inetAddressAndPortSerializer.deserialize(in, minMessagingVersion);
int computed = computeCrc32(nio, start, nio.position());
int read = in.readInt();
if (read != computed)
throw new InvalidCrc(read, computed);
buf.skipBytes(nio.position() - start);
return new Initiate(new AcceptVersions(minMessagingVersion, maxMessagingVersion), type, framing, from);
}
catch (EOFException e)
{
return null;
}
}
@Override
public boolean equals(Object other)
{
if (!(other instanceof Initiate))
return false;
Initiate that = (Initiate)other;
return this.type == that.type
&& this.framing == that.framing
&& Objects.equals(this.acceptVersions, that.acceptVersions);
}
@Override
public String toString()
{
return String.format("Initiate(min: %d, max: %d, type: %s, framing: %b, from: %s)",
acceptVersions.min,
acceptVersions.max,
type, framing, from);
}
}
/**
* The second message of the handshake, sent by the node receiving the {@link Initiate} back to the
* connection initiator.
*
* This message contains
* 1) the messaging version of the peer sending this message
* 2) the negotiated messaging version if one could be accepted by both peers,
* or if not the closest version that this peer could support to the ones requested
* 3) a CRC protecting the integrity of the message
*
*/
static class Accept
{
/** The messaging version sent by the receiving peer (int). */
private static final int MAX_LENGTH = 12;
final int useMessagingVersion;
final int maxMessagingVersion;
Accept(int useMessagingVersion, int maxMessagingVersion)
{
this.useMessagingVersion = useMessagingVersion;
this.maxMessagingVersion = maxMessagingVersion;
}
ByteBuf encode(ByteBufAllocator allocator)
{
ByteBuf buffer = allocator.directBuffer(MAX_LENGTH);
buffer.clear();
buffer.writeInt(maxMessagingVersion);
buffer.writeInt(useMessagingVersion);
buffer.writeInt(computeCrc32(buffer, 0, 8));
return buffer;
}
static Accept maybeDecode(ByteBuf in) throws InvalidCrc
{
int readerIndex = in.readerIndex();
if (in.readableBytes() < 4)
return null;
int maxMessagingVersion = in.readInt();
int useMessagingVersion = 0;
// pre-4.0 not supported, close the connection
if (maxMessagingVersion < VERSION_40)
return null;
if (in.readableBytes() < 8)
{
in.readerIndex(readerIndex);
return null;
}
useMessagingVersion = in.readInt();
// verify crc
int computed = computeCrc32(in, readerIndex, readerIndex + 8);
int read = in.readInt();
if (read != computed)
throw new InvalidCrc(read, computed);
return new Accept(useMessagingVersion, maxMessagingVersion);
}
@Override
public boolean equals(Object other)
{
return other instanceof Accept
&& this.useMessagingVersion == ((Accept) other).useMessagingVersion
&& this.maxMessagingVersion == ((Accept) other).maxMessagingVersion;
}
@Override
public String toString()
{
return String.format("Accept(use: %d, max: %d)", useMessagingVersion, maxMessagingVersion);
}
}
private static int getBits(int packed, int start, int count)
{
return (packed >>> start) & ~(-1 << count);
}
}
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