/*
* 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.http;
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.http.HttpHeaders.Names;
import com.facebook.presto.jdbc.internal.netty.handler.codec.http.HttpHeaders.Values;
import com.facebook.presto.jdbc.internal.netty.handler.codec.oneone.OneToOneEncoder;
import com.facebook.presto.jdbc.internal.netty.util.CharsetUtil;
import java.io.UnsupportedEncodingException;
import java.util.Map;
import static com.facebook.presto.jdbc.internal.netty.buffer.ChannelBuffers.*;
import static com.facebook.presto.jdbc.internal.netty.handler.codec.http.HttpConstants.*;
/**
* Encodes an {@link HttpMessage} or an {@link HttpChunk} into
* a {@link ChannelBuffer}.
*
* <h3>Extensibility</h3>
*
* Please note that this encoder is designed to be extended to implement
* a protocol derived from HTTP, such as
* <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
* <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>.
* To implement the encoder of such a derived protocol, extend this class and
* implement all abstract methods properly.
* @apiviz.landmark
*/
public abstract class HttpMessageEncoder extends OneToOneEncoder {
private static final byte[] CRLF = { CR, LF };
private static final ChannelBuffer LAST_CHUNK =
copiedBuffer("0\r\n\r\n", CharsetUtil.US_ASCII);
private volatile boolean transferEncodingChunked;
/**
* Creates a new instance.
*/
protected HttpMessageEncoder() {
}
@Override
protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
if (msg instanceof HttpMessage) {
HttpMessage m = (HttpMessage) msg;
boolean contentMustBeEmpty;
if (m.isChunked()) {
// if Content-Length is set then the message can't be HTTP chunked
if (HttpCodecUtil.isContentLengthSet(m)) {
contentMustBeEmpty = false;
transferEncodingChunked = false;
HttpCodecUtil.removeTransferEncodingChunked(m);
} else {
// check if the Transfer-Encoding is set to chunked already.
// if not add the header to the message
if (!HttpCodecUtil.isTransferEncodingChunked(m)) {
m.addHeader(Names.TRANSFER_ENCODING, Values.CHUNKED);
}
contentMustBeEmpty = true;
transferEncodingChunked = true;
}
} else {
transferEncodingChunked = contentMustBeEmpty = HttpCodecUtil.isTransferEncodingChunked(m);
}
ChannelBuffer header = dynamicBuffer(
channel.getConfig().getBufferFactory());
encodeInitialLine(header, m);
encodeHeaders(header, m);
header.writeByte(CR);
header.writeByte(LF);
ChannelBuffer content = m.getContent();
if (!content.readable()) {
return header; // no content
} else if (contentMustBeEmpty) {
throw new IllegalArgumentException(
"HttpMessage.content must be empty " +
"if Transfer-Encoding is chunked.");
} else {
return wrappedBuffer(header, content);
}
}
if (msg instanceof HttpChunk) {
HttpChunk chunk = (HttpChunk) msg;
if (transferEncodingChunked) {
if (chunk.isLast()) {
transferEncodingChunked = false;
if (chunk instanceof HttpChunkTrailer) {
ChannelBuffer trailer = dynamicBuffer(
channel.getConfig().getBufferFactory());
trailer.writeByte((byte) '0');
trailer.writeByte(CR);
trailer.writeByte(LF);
encodeTrailingHeaders(trailer, (HttpChunkTrailer) chunk);
trailer.writeByte(CR);
trailer.writeByte(LF);
return trailer;
} else {
return LAST_CHUNK.duplicate();
}
} else {
ChannelBuffer content = chunk.getContent();
int contentLength = content.readableBytes();
return wrappedBuffer(
copiedBuffer(
Integer.toHexString(contentLength),
CharsetUtil.US_ASCII),
wrappedBuffer(CRLF),
content.slice(content.readerIndex(), contentLength),
wrappedBuffer(CRLF));
}
} else {
return chunk.getContent();
}
}
// Unknown message type.
return msg;
}
private static void encodeHeaders(ChannelBuffer buf, HttpMessage message) {
try {
for (Map.Entry<String, String> h: message.getHeaders()) {
encodeHeader(buf, h.getKey(), h.getValue());
}
} catch (UnsupportedEncodingException e) {
throw (Error) new Error().initCause(e);
}
}
private static void encodeTrailingHeaders(ChannelBuffer buf, HttpChunkTrailer trailer) {
try {
for (Map.Entry<String, String> h: trailer.getHeaders()) {
encodeHeader(buf, h.getKey(), h.getValue());
}
} catch (UnsupportedEncodingException e) {
throw (Error) new Error().initCause(e);
}
}
private static void encodeHeader(ChannelBuffer buf, String header, String value)
throws UnsupportedEncodingException {
encodeAscii(header, buf);
buf.writeByte(COLON);
buf.writeByte(SP);
encodeAscii(value, buf);
buf.writeByte(CR);
buf.writeByte(LF);
}
protected static void encodeAscii(String s, ChannelBuffer buf) {
for (int i = 0; i < s.length(); i++) {
buf.writeByte(s.charAt(i));
}
}
protected abstract void encodeInitialLine(ChannelBuffer buf, HttpMessage message) throws Exception;
}