/*
* 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 io.netty.handler.codec.http;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.FileRegion;
import io.netty.handler.codec.MessageToMessageEncoder;
import io.netty.util.CharsetUtil;
import io.netty.util.internal.StringUtil;
import java.util.List;
import static io.netty.buffer.Unpooled.*;
import static io.netty.handler.codec.http.HttpConstants.*;
/**
* Encodes an {@link HttpMessage} or an {@link HttpContent} into
* a {@link ByteBuf}.
*
* <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.
*/
public abstract class HttpObjectEncoder<H extends HttpMessage> extends MessageToMessageEncoder<Object> {
private static final byte[] CRLF = { CR, LF };
private static final byte[] ZERO_CRLF = { '0', CR, LF };
private static final byte[] ZERO_CRLF_CRLF = { '0', CR, LF, CR, LF };
private static final ByteBuf CRLF_BUF = unreleasableBuffer(directBuffer(CRLF.length).writeBytes(CRLF));
private static final ByteBuf ZERO_CRLF_CRLF_BUF = unreleasableBuffer(directBuffer(ZERO_CRLF_CRLF.length)
.writeBytes(ZERO_CRLF_CRLF));
private static final int ST_INIT = 0;
private static final int ST_CONTENT_NON_CHUNK = 1;
private static final int ST_CONTENT_CHUNK = 2;
@SuppressWarnings("RedundantFieldInitialization")
private int state = ST_INIT;
@Override
protected void encode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
ByteBuf buf = null;
if (msg instanceof HttpMessage) {
if (state != ST_INIT) {
throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
}
@SuppressWarnings({ "unchecked", "CastConflictsWithInstanceof" })
H m = (H) msg;
buf = ctx.alloc().buffer();
// Encode the message.
encodeInitialLine(buf, m);
encodeHeaders(m.headers(), buf);
buf.writeBytes(CRLF);
state = HttpHeaders.isTransferEncodingChunked(m) ? ST_CONTENT_CHUNK : ST_CONTENT_NON_CHUNK;
}
// Bypass the encoder in case of an empty buffer, so that the following idiom works:
//
// ch.write(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
//
// See https://github.com/netty/netty/issues/2983 for more information.
if (msg instanceof ByteBuf && !((ByteBuf) msg).isReadable()) {
out.add(EMPTY_BUFFER);
return;
}
if (msg instanceof HttpContent || msg instanceof ByteBuf || msg instanceof FileRegion) {
if (state == ST_INIT) {
throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
}
final long contentLength = contentLength(msg);
if (state == ST_CONTENT_NON_CHUNK) {
if (contentLength > 0) {
if (buf != null && buf.writableBytes() >= contentLength && msg instanceof HttpContent) {
// merge into other buffer for performance reasons
buf.writeBytes(((HttpContent) msg).content());
out.add(buf);
} else {
if (buf != null) {
out.add(buf);
}
out.add(encodeAndRetain(msg));
}
} else {
if (buf != null) {
out.add(buf);
} else {
// Need to produce some output otherwise an
// IllegalStateException will be thrown
out.add(EMPTY_BUFFER);
}
}
if (msg instanceof LastHttpContent) {
state = ST_INIT;
}
} else if (state == ST_CONTENT_CHUNK) {
if (buf != null) {
out.add(buf);
}
encodeChunkedContent(ctx, msg, contentLength, out);
} else {
throw new Error();
}
} else {
if (buf != null) {
out.add(buf);
}
}
}
/**
* Encode the {@link HttpHeaders} into a {@link ByteBuf}.
*/
protected void encodeHeaders(HttpHeaders headers, ByteBuf buf) {
HttpHeaders.encode(headers, buf);
}
private void encodeChunkedContent(ChannelHandlerContext ctx, Object msg, long contentLength, List<Object> out) {
if (contentLength > 0) {
byte[] length = Long.toHexString(contentLength).getBytes(CharsetUtil.US_ASCII);
ByteBuf buf = ctx.alloc().buffer(length.length + 2);
buf.writeBytes(length);
buf.writeBytes(CRLF);
out.add(buf);
out.add(encodeAndRetain(msg));
out.add(CRLF_BUF.duplicate());
}
if (msg instanceof LastHttpContent) {
HttpHeaders headers = ((LastHttpContent) msg).trailingHeaders();
if (headers.isEmpty()) {
out.add(ZERO_CRLF_CRLF_BUF.duplicate());
} else {
ByteBuf buf = ctx.alloc().buffer();
buf.writeBytes(ZERO_CRLF);
encodeHeaders(headers, buf);
buf.writeBytes(CRLF);
out.add(buf);
}
state = ST_INIT;
} else {
if (contentLength == 0) {
// Need to produce some output otherwise an
// IllegalstateException will be thrown
out.add(EMPTY_BUFFER);
}
}
}
@Override
public boolean acceptOutboundMessage(Object msg) throws Exception {
return msg instanceof HttpObject || msg instanceof ByteBuf || msg instanceof FileRegion;
}
private static Object encodeAndRetain(Object msg) {
if (msg instanceof ByteBuf) {
return ((ByteBuf) msg).retain();
}
if (msg instanceof HttpContent) {
return ((HttpContent) msg).content().retain();
}
if (msg instanceof FileRegion) {
return ((FileRegion) msg).retain();
}
throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
}
private static long contentLength(Object msg) {
if (msg instanceof HttpContent) {
return ((HttpContent) msg).content().readableBytes();
}
if (msg instanceof ByteBuf) {
return ((ByteBuf) msg).readableBytes();
}
if (msg instanceof FileRegion) {
return ((FileRegion) msg).count();
}
throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
}
@Deprecated
protected static void encodeAscii(String s, ByteBuf buf) {
HttpHeaders.encodeAscii0(s, buf);
}
protected abstract void encodeInitialLine(ByteBuf buf, H message) throws Exception;
}