/*
* Copyright 2014 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.http2;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.compression.ZlibCodecFactory;
import io.netty.handler.codec.compression.ZlibWrapper;
import io.netty.util.concurrent.PromiseCombiner;
import io.netty.util.internal.UnstableApi;
import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_ENCODING;
import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_LENGTH;
import static io.netty.handler.codec.http.HttpHeaderValues.DEFLATE;
import static io.netty.handler.codec.http.HttpHeaderValues.GZIP;
import static io.netty.handler.codec.http.HttpHeaderValues.IDENTITY;
import static io.netty.handler.codec.http.HttpHeaderValues.X_DEFLATE;
import static io.netty.handler.codec.http.HttpHeaderValues.X_GZIP;
/**
* A decorating HTTP2 encoder that will compress data frames according to the {@code content-encoding} header for each
* stream. The compression provided by this class will be applied to the data for the entire stream.
*/
@UnstableApi
public class CompressorHttp2ConnectionEncoder extends DecoratingHttp2ConnectionEncoder {
public static final int DEFAULT_COMPRESSION_LEVEL = 6;
public static final int DEFAULT_WINDOW_BITS = 15;
public static final int DEFAULT_MEM_LEVEL = 8;
private final int compressionLevel;
private final int windowBits;
private final int memLevel;
private final Http2Connection.PropertyKey propertyKey;
public CompressorHttp2ConnectionEncoder(Http2ConnectionEncoder delegate) {
this(delegate, DEFAULT_COMPRESSION_LEVEL, DEFAULT_WINDOW_BITS, DEFAULT_MEM_LEVEL);
}
public CompressorHttp2ConnectionEncoder(Http2ConnectionEncoder delegate, int compressionLevel, int windowBits,
int memLevel) {
super(delegate);
if (compressionLevel < 0 || compressionLevel > 9) {
throw new IllegalArgumentException("compressionLevel: " + compressionLevel + " (expected: 0-9)");
}
if (windowBits < 9 || windowBits > 15) {
throw new IllegalArgumentException("windowBits: " + windowBits + " (expected: 9-15)");
}
if (memLevel < 1 || memLevel > 9) {
throw new IllegalArgumentException("memLevel: " + memLevel + " (expected: 1-9)");
}
this.compressionLevel = compressionLevel;
this.windowBits = windowBits;
this.memLevel = memLevel;
propertyKey = connection().newKey();
connection().addListener(new Http2ConnectionAdapter() {
@Override
public void onStreamRemoved(Http2Stream stream) {
final EmbeddedChannel compressor = stream.getProperty(propertyKey);
if (compressor != null) {
cleanup(stream, compressor);
}
}
});
}
@Override
public ChannelFuture writeData(final ChannelHandlerContext ctx, final int streamId, ByteBuf data, int padding,
final boolean endOfStream, ChannelPromise promise) {
final Http2Stream stream = connection().stream(streamId);
final EmbeddedChannel channel = stream == null ? null : (EmbeddedChannel) stream.getProperty(propertyKey);
if (channel == null) {
// The compressor may be null if no compatible encoding type was found in this stream's headers
return super.writeData(ctx, streamId, data, padding, endOfStream, promise);
}
try {
// The channel will release the buffer after being written
channel.writeOutbound(data);
ByteBuf buf = nextReadableBuf(channel);
if (buf == null) {
if (endOfStream) {
if (channel.finish()) {
buf = nextReadableBuf(channel);
}
return super.writeData(ctx, streamId, buf == null ? Unpooled.EMPTY_BUFFER : buf, padding,
true, promise);
}
// END_STREAM is not set and the assumption is data is still forthcoming.
promise.setSuccess();
return promise;
}
PromiseCombiner combiner = new PromiseCombiner();
for (;;) {
ByteBuf nextBuf = nextReadableBuf(channel);
boolean compressedEndOfStream = nextBuf == null && endOfStream;
if (compressedEndOfStream && channel.finish()) {
nextBuf = nextReadableBuf(channel);
compressedEndOfStream = nextBuf == null;
}
ChannelPromise bufPromise = ctx.newPromise();
combiner.add(bufPromise);
super.writeData(ctx, streamId, buf, padding, compressedEndOfStream, bufPromise);
if (nextBuf == null) {
break;
}
padding = 0; // Padding is only communicated once on the first iteration
buf = nextBuf;
}
combiner.finish(promise);
} catch (Throwable cause) {
promise.tryFailure(cause);
} finally {
if (endOfStream) {
cleanup(stream, channel);
}
}
return promise;
}
@Override
public ChannelFuture writeHeaders(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int padding,
boolean endStream, ChannelPromise promise) {
try {
// Determine if compression is required and sanitize the headers.
EmbeddedChannel compressor = newCompressor(ctx, headers, endStream);
// Write the headers and create the stream object.
ChannelFuture future = super.writeHeaders(ctx, streamId, headers, padding, endStream, promise);
// After the stream object has been created, then attach the compressor as a property for data compression.
bindCompressorToStream(compressor, streamId);
return future;
} catch (Throwable e) {
promise.tryFailure(e);
}
return promise;
}
@Override
public ChannelFuture writeHeaders(final ChannelHandlerContext ctx, final int streamId, final Http2Headers headers,
final int streamDependency, final short weight, final boolean exclusive, final int padding,
final boolean endOfStream, final ChannelPromise promise) {
try {
// Determine if compression is required and sanitize the headers.
EmbeddedChannel compressor = newCompressor(ctx, headers, endOfStream);
// Write the headers and create the stream object.
ChannelFuture future = super.writeHeaders(ctx, streamId, headers, streamDependency, weight, exclusive,
padding, endOfStream, promise);
// After the stream object has been created, then attach the compressor as a property for data compression.
bindCompressorToStream(compressor, streamId);
return future;
} catch (Throwable e) {
promise.tryFailure(e);
}
return promise;
}
/**
* Returns a new {@link EmbeddedChannel} that encodes the HTTP2 message content encoded in the specified
* {@code contentEncoding}.
*
* @param ctx the context.
* @param contentEncoding the value of the {@code content-encoding} header
* @return a new {@link ByteToMessageDecoder} if the specified encoding is supported. {@code null} otherwise
* (alternatively, you can throw a {@link Http2Exception} to block unknown encoding).
* @throws Http2Exception If the specified encoding is not not supported and warrants an exception
*/
protected EmbeddedChannel newContentCompressor(ChannelHandlerContext ctx, CharSequence contentEncoding)
throws Http2Exception {
if (GZIP.contentEqualsIgnoreCase(contentEncoding) || X_GZIP.contentEqualsIgnoreCase(contentEncoding)) {
return newCompressionChannel(ctx, ZlibWrapper.GZIP);
}
if (DEFLATE.contentEqualsIgnoreCase(contentEncoding) || X_DEFLATE.contentEqualsIgnoreCase(contentEncoding)) {
return newCompressionChannel(ctx, ZlibWrapper.ZLIB);
}
// 'identity' or unsupported
return null;
}
/**
* Returns the expected content encoding of the decoded content. Returning {@code contentEncoding} is the default
* behavior, which is the case for most compressors.
*
* @param contentEncoding the value of the {@code content-encoding} header
* @return the expected content encoding of the new content.
* @throws Http2Exception if the {@code contentEncoding} is not supported and warrants an exception
*/
protected CharSequence getTargetContentEncoding(CharSequence contentEncoding) throws Http2Exception {
return contentEncoding;
}
/**
* Generate a new instance of an {@link EmbeddedChannel} capable of compressing data
* @param ctx the context.
* @param wrapper Defines what type of encoder should be used
*/
private EmbeddedChannel newCompressionChannel(final ChannelHandlerContext ctx, ZlibWrapper wrapper) {
return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(wrapper, compressionLevel, windowBits,
memLevel));
}
/**
* Checks if a new compressor object is needed for the stream identified by {@code streamId}. This method will
* modify the {@code content-encoding} header contained in {@code headers}.
*
* @param ctx the context.
* @param headers Object representing headers which are to be written
* @param endOfStream Indicates if the stream has ended
* @return The channel used to compress data.
* @throws Http2Exception if any problems occur during initialization.
*/
private EmbeddedChannel newCompressor(ChannelHandlerContext ctx, Http2Headers headers, boolean endOfStream)
throws Http2Exception {
if (endOfStream) {
return null;
}
CharSequence encoding = headers.get(CONTENT_ENCODING);
if (encoding == null) {
encoding = IDENTITY;
}
final EmbeddedChannel compressor = newContentCompressor(ctx, encoding);
if (compressor != null) {
CharSequence targetContentEncoding = getTargetContentEncoding(encoding);
if (IDENTITY.contentEqualsIgnoreCase(targetContentEncoding)) {
headers.remove(CONTENT_ENCODING);
} else {
headers.set(CONTENT_ENCODING, targetContentEncoding);
}
// The content length will be for the decompressed data. Since we will compress the data
// this content-length will not be correct. Instead of queuing messages or delaying sending
// header frames...just remove the content-length header
headers.remove(CONTENT_LENGTH);
}
return compressor;
}
/**
* Called after the super class has written the headers and created any associated stream objects.
* @param compressor The compressor associated with the stream identified by {@code streamId}.
* @param streamId The stream id for which the headers were written.
*/
private void bindCompressorToStream(EmbeddedChannel compressor, int streamId) {
if (compressor != null) {
Http2Stream stream = connection().stream(streamId);
if (stream != null) {
stream.setProperty(propertyKey, compressor);
}
}
}
/**
* Release remaining content from {@link EmbeddedChannel} and remove the compressor from the {@link Http2Stream}.
*
* @param stream The stream for which {@code compressor} is the compressor for
* @param compressor The compressor for {@code stream}
*/
void cleanup(Http2Stream stream, EmbeddedChannel compressor) {
if (compressor.finish()) {
for (;;) {
final ByteBuf buf = compressor.readOutbound();
if (buf == null) {
break;
}
buf.release();
}
}
stream.removeProperty(propertyKey);
}
/**
* Read the next compressed {@link ByteBuf} from the {@link EmbeddedChannel} or {@code null} if one does not exist.
*
* @param compressor The channel to read from
* @return The next decoded {@link ByteBuf} from the {@link EmbeddedChannel} or {@code null} if one does not exist
*/
private static ByteBuf nextReadableBuf(EmbeddedChannel compressor) {
for (;;) {
final ByteBuf buf = compressor.readOutbound();
if (buf == null) {
return null;
}
if (!buf.isReadable()) {
buf.release();
continue;
}
return buf;
}
}
}