com.acgist.snail.net.torrent.PeerUnpackMessageCodec Maven / Gradle / Ivy
package com.acgist.snail.net.torrent;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import com.acgist.snail.net.codec.MessageCodec;
import com.acgist.snail.net.torrent.peer.bootstrap.PeerSubMessageHandler;
import com.acgist.snail.system.config.PeerConfig;
import com.acgist.snail.system.config.SystemConfig;
import com.acgist.snail.system.exception.NetException;
import com.acgist.snail.system.exception.PacketSizeException;
/**
* Peer消息处理器：拆包
*
* TODO：握手消息匹配协议名称
*
* @author acgist
* @since 1.1.0
*/
public final class PeerUnpackMessageCodec extends MessageCodec {
/**
* int字符长度
*/
private static final int INT_BYTE_LENGTH = 4;
/**
* 完整消息缓存
* 消息按照长度读入进入消息缓存
*/
private ByteBuffer buffer;
/**
* 消息长度
*/
private final ByteBuffer lengthStick;
/**
* Peer代理
*/
private final PeerSubMessageHandler peerSubMessageHandler;
public PeerUnpackMessageCodec(PeerSubMessageHandler peerSubMessageHandler) {
super(peerSubMessageHandler);
this.lengthStick = ByteBuffer.allocate(INT_BYTE_LENGTH);
this.peerSubMessageHandler = peerSubMessageHandler;
}
@Override
public void decode(ByteBuffer buffer, InetSocketAddress address, boolean haveAddress) throws NetException {
int length = 0; // 消息数据长度
while(true) {
if(this.buffer == null) {
if(this.peerSubMessageHandler.handshake()) {
for (int index = 0; index < buffer.limit() && buffer.hasRemaining(); index++) {
this.lengthStick.put(buffer.get());
if(this.lengthStick.position() == INT_BYTE_LENGTH) {
break;
}
}
if(this.lengthStick.position() == INT_BYTE_LENGTH) {
this.lengthStick.flip();
length = this.lengthStick.getInt();
this.lengthStick.compact();
} else { // 消息长度读取不完整跳出
break;
}
} else { // 握手消息长度
length = PeerConfig.HANDSHAKE_LENGTH;
}
// 心跳消息：如果还有消息内容继续处理，否者跳出循环。
if(length <= 0) {
this.peerSubMessageHandler.keepAlive();
if(buffer.hasRemaining()) {
continue;
} else {
break;
}
} else if(length >= SystemConfig.MAX_NET_BUFFER_LENGTH || length < 0) {
throw new PacketSizeException(length);
}
this.buffer = ByteBuffer.allocate(length);
} else {
// 上次消息没有读取完成，计算剩余消息数据长度。
length = this.buffer.capacity() - this.buffer.position();
}
final int remaining = buffer.remaining();
if(remaining > length) { // 包含一条完整消息：处理完成后继续读取
final byte[] bytes = new byte[length];
buffer.get(bytes);
this.buffer.put(bytes);
this.doNext(this.buffer, address, haveAddress);
this.buffer = null;
} else if(remaining == length) { // 刚好一条完整消息：处理完成后跳出循环
final byte[] bytes = new byte[length];
buffer.get(bytes);
this.buffer.put(bytes);
this.doNext(this.buffer, address, haveAddress);
this.buffer = null;
break;
} else if(remaining < length) { // 不是一条完整消息：跳出循环等待后续数据
final byte[] bytes = new byte[remaining];
buffer.get(bytes);
this.buffer.put(bytes);
break;
}
}
}
}