netty.syslog.MessageFramer.java Source code

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Here is the source code for netty.syslog.MessageFramer.java

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/*
 *   Copyright (c) 2014 Intellectual Reserve, Inc.  All rights reserved.
 *
 *   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 netty.syslog;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ReplayingDecoder;
import io.netty.handler.codec.TooLongFrameException;

import static netty.syslog.DecoderUtil.*;

import java.util.List;

/**
 * Frames syslog messages per RFC-6587.
 */
public class MessageFramer extends ReplayingDecoder<ByteBuf> {

    public static final int DEFAULT_MAX_MESSAGE_SIZE = 64 * 1024;

    private final int maxMessageSize;

    public MessageFramer() {
        this(DEFAULT_MAX_MESSAGE_SIZE);
    }

    public MessageFramer(int maxMessageSize) {
        this.maxMessageSize = maxMessageSize;
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf buffer, List<Object> out) throws Exception {
        if (buffer.readableBytes() > 0) {
            // Decode the content length
            final int length = readDigit(buffer);
            expect(buffer, ' ');
            if (length > maxMessageSize) {
                throw new TooLongFrameException(
                        "Received a message of length " + length + ", maximum message length is " + maxMessageSize);
            }
            out.add(buffer.readSlice(length).retain());
        }
    }

}