/*
* Copyright 2012 The Netty Project
*
* The Netty Project 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 com.facebook.presto.jdbc.internal.netty.handler.codec.rtsp;
import com.facebook.presto.jdbc.internal.netty.buffer.ChannelBuffer;
import com.facebook.presto.jdbc.internal.netty.channel.Channel;
import com.facebook.presto.jdbc.internal.netty.channel.ChannelHandlerContext;
import com.facebook.presto.jdbc.internal.netty.handler.codec.embedder.DecoderEmbedder;
import com.facebook.presto.jdbc.internal.netty.handler.codec.frame.TooLongFrameException;
import com.facebook.presto.jdbc.internal.netty.handler.codec.http.HttpChunkAggregator;
import com.facebook.presto.jdbc.internal.netty.handler.codec.http.HttpMessage;
import com.facebook.presto.jdbc.internal.netty.handler.codec.http.HttpMessageDecoder;
/**
* Decodes {@link ChannelBuffer}s into RTSP messages represented in
* {@link HttpMessage}s.
* <p>
* <h3>Parameters that prevents excessive memory consumption</h3>
* <table border="1">
* <tr>
* <th>Name</th><th>Meaning</th>
* </tr>
* <tr>
* <td>{@code maxInitialLineLength}</td>
* <td>The maximum length of the initial line
* (e.g. {@code "SETUP / RTSP/1.0"} or {@code "RTSP/1.0 200 OK"})
* If the length of the initial line exceeds this value, a
* {@link TooLongFrameException} will be raised.</td>
* </tr>
* <tr>
* <td>{@code maxHeaderSize}</td>
* <td>The maximum length of all headers. If the sum of the length of each
* header exceeds this value, a {@link TooLongFrameException} will be raised.</td>
* </tr>
* <tr>
* <td>{@code maxContentLength}</td>
* <td>The maximum length of the content. If the content length exceeds this
* value, a {@link TooLongFrameException} will be raised.</td>
* </tr>
* </table>
* @apiviz.landmark
*/
public abstract class RtspMessageDecoder extends HttpMessageDecoder {
private final DecoderEmbedder<HttpMessage> aggregator;
/**
* Creates a new instance with the default
* {@code maxInitialLineLength (4096}}, {@code maxHeaderSize (8192)}, and
* {@code maxContentLength (8192)}.
*/
protected RtspMessageDecoder() {
this(4096, 8192, 8192);
}
/**
* Creates a new instance with the specified parameters.
*/
protected RtspMessageDecoder(int maxInitialLineLength, int maxHeaderSize, int maxContentLength) {
super(maxInitialLineLength, maxHeaderSize, maxContentLength * 2);
aggregator = new DecoderEmbedder<HttpMessage>(new HttpChunkAggregator(maxContentLength));
}
@Override
protected Object decode(ChannelHandlerContext ctx, Channel channel,
ChannelBuffer buffer, State state) throws Exception {
Object o = super.decode(ctx, channel, buffer, state);
if (o != null && aggregator.offer(o)) {
return aggregator.poll();
} else {
return null;
}
}
@Override
protected boolean isContentAlwaysEmpty(HttpMessage msg) {
// Unlike HTTP, RTSP always assumes zero-length body if Content-Length
// header is absent.
boolean empty = super.isContentAlwaysEmpty(msg);
if (empty) {
return true;
}
if (!msg.containsHeader(RtspHeaders.Names.CONTENT_LENGTH)) {
return true;
}
return empty;
}
}