/*
* 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.handler.codec.MessageToByteEncoder;
import io.netty.util.CharsetUtil;
import java.util.Map;
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 MessageToByteEncoder<HttpObject> {
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, HttpObject msg, ByteBuf out) throws Exception {
if (msg instanceof HttpMessage) {
if (state != ST_INIT) {
throw new IllegalStateException("unexpected message type: " + msg.getClass().getSimpleName());
}
@SuppressWarnings({ "unchecked", "CastConflictsWithInstanceof" })
H m = (H) msg;
// Encode the message.
encodeInitialLine(out, m);
encodeHeaders(out, m);
out.writeByte(CR);
out.writeByte(LF);
state = HttpHeaders.isTransferEncodingChunked(m) ? ST_CONTENT_CHUNK : ST_CONTENT_NON_CHUNK;
}
if (msg instanceof HttpContent) {
if (state == ST_INIT) {
throw new IllegalStateException("unexpected message type: " + msg.getClass().getSimpleName());
}
HttpContent chunk = (HttpContent) msg;
ByteBuf content = chunk.data();
int contentLength = content.readableBytes();
if (state == ST_CONTENT_NON_CHUNK) {
if (contentLength > 0) {
out.writeBytes(content, content.readerIndex(), content.readableBytes());
}
if (chunk instanceof LastHttpContent) {
state = ST_INIT;
}
} else if (state == ST_CONTENT_CHUNK) {
if (contentLength > 0) {
out.writeBytes(copiedBuffer(Integer.toHexString(contentLength), CharsetUtil.US_ASCII));
out.writeByte(CR);
out.writeByte(LF);
out.writeBytes(content, content.readerIndex(), contentLength);
out.writeByte(CR);
out.writeByte(LF);
}
if (chunk instanceof LastHttpContent) {
out.writeByte((byte) '0');
out.writeByte(CR);
out.writeByte(LF);
encodeTrailingHeaders(out, (LastHttpContent) chunk);
out.writeByte(CR);
out.writeByte(LF);
state = ST_INIT;
}
} else {
throw new Error();
}
}
}
private static void encodeHeaders(ByteBuf buf, HttpMessage message) {
for (Map.Entry<String, String> h: message.headers()) {
encodeHeader(buf, h.getKey(), h.getValue());
}
}
private static void encodeTrailingHeaders(ByteBuf buf, LastHttpContent trailer) {
for (Map.Entry<String, String> h: trailer.trailingHeaders()) {
encodeHeader(buf, h.getKey(), h.getValue());
}
}
private static void encodeHeader(ByteBuf buf, String header, String value) {
buf.writeBytes(header.getBytes(CharsetUtil.US_ASCII));
buf.writeByte(COLON);
buf.writeByte(SP);
buf.writeBytes(value.getBytes(CharsetUtil.US_ASCII));
buf.writeByte(CR);
buf.writeByte(LF);
}
protected abstract void encodeInitialLine(ByteBuf buf, H message) throws Exception;
}