org.graylog2.inputs.syslog.tcp.SyslogTCPFramingRouterHandler Maven / Gradle / Ivy
/*
* Copyright (C) 2020 Graylog, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* .
*/
package org.graylog2.inputs.syslog.tcp;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandler;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.util.ReferenceCountUtil;
public class SyslogTCPFramingRouterHandler extends SimpleChannelInboundHandler {
private final int maxFrameLength;
private final ByteBuf[] delimiter;
private ChannelInboundHandler handler = null;
public SyslogTCPFramingRouterHandler(int maxFrameLength, ByteBuf[] delimiter) {
this.maxFrameLength = maxFrameLength;
this.delimiter = delimiter;
}
@Override
protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
if (msg.isReadable()) {
// "Dynamically manipulating a pipeline is relatively an expensive operation."
// https://stackoverflow.com/a/28846565
if (handler == null) {
if (usesOctetCountFraming(msg)) {
handler = new SyslogOctetCountFrameDecoder();
} else {
handler = new DelimiterBasedFrameDecoder(maxFrameLength, delimiter);
}
}
handler.channelRead(ctx, ReferenceCountUtil.retain(msg));
} else {
ctx.fireChannelRead(msg);
}
}
private boolean usesOctetCountFraming(ByteBuf message) {
// Octet counting framing needs to start with a non-zero digit.
// See: http://tools.ietf.org/html/rfc6587#section-3.4.1
final byte firstByte = message.getByte(0);
return '0' < firstByte && firstByte <= '9';
}
}