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/*
* 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.channel.ChannelHandlerContext;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.compression.ZlibCodecFactory;
import io.netty.handler.codec.compression.ZlibWrapper;
/**
* Compresses an {@link HttpMessage} and an {@link HttpContent} in {@code gzip} or
* {@code deflate} encoding while respecting the {@code "Accept-Encoding"} header.
* If there is no matching encoding, no compression is done. For more
* information on how this handler modifies the message, please refer to
* {@link HttpContentEncoder}.
*/
public class HttpContentCompressor extends HttpContentEncoder {
private final int compressionLevel;
private final int windowBits;
private final int memLevel;
private final int contentSizeThreshold;
private ChannelHandlerContext ctx;
/**
* Creates a new handler with the default compression level (6),
* default window size (15) and default memory level (8).
*/
public HttpContentCompressor() {
this(6);
}
/**
* Creates a new handler with the specified compression level, default
* window size (15) and default memory level (8).
*
* @param compressionLevel
* {@code 1} yields the fastest compression and {@code 9} yields the
* best compression. {@code 0} means no compression. The default
* compression level is {@code 6}.
*/
public HttpContentCompressor(int compressionLevel) {
this(compressionLevel, 15, 8, 0);
}
/**
* Creates a new handler with the specified compression level, window size,
* and memory level..
*
* @param compressionLevel
* {@code 1} yields the fastest compression and {@code 9} yields the
* best compression. {@code 0} means no compression. The default
* compression level is {@code 6}.
* @param windowBits
* The base two logarithm of the size of the history buffer. The
* value should be in the range {@code 9} to {@code 15} inclusive.
* Larger values result in better compression at the expense of
* memory usage. The default value is {@code 15}.
* @param memLevel
* How much memory should be allocated for the internal compression
* state. {@code 1} uses minimum memory and {@code 9} uses maximum
* memory. Larger values result in better and faster compression
* at the expense of memory usage. The default value is {@code 8}
*/
public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel) {
this(compressionLevel, windowBits, memLevel, 0);
}
/**
* Creates a new handler with the specified compression level, window size,
* and memory level..
*
* @param compressionLevel
* {@code 1} yields the fastest compression and {@code 9} yields the
* best compression. {@code 0} means no compression. The default
* compression level is {@code 6}.
* @param windowBits
* The base two logarithm of the size of the history buffer. The
* value should be in the range {@code 9} to {@code 15} inclusive.
* Larger values result in better compression at the expense of
* memory usage. The default value is {@code 15}.
* @param memLevel
* How much memory should be allocated for the internal compression
* state. {@code 1} uses minimum memory and {@code 9} uses maximum
* memory. Larger values result in better and faster compression
* at the expense of memory usage. The default value is {@code 8}
* @param contentSizeThreshold
* The response body is compressed when the size of the response
* body exceeds the threshold. The value should be a non negative
* number. {@code 0} will enable compression for all responses.
*/
public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel, int contentSizeThreshold) {
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)");
}
if (contentSizeThreshold < 0) {
throw new IllegalArgumentException(
"contentSizeThreshold: " + contentSizeThreshold + " (expected: non negative number)");
}
this.compressionLevel = compressionLevel;
this.windowBits = windowBits;
this.memLevel = memLevel;
this.contentSizeThreshold = contentSizeThreshold;
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
this.ctx = ctx;
}
@Override
protected Result beginEncode(HttpResponse httpResponse, String acceptEncoding) throws Exception {
if (this.contentSizeThreshold > 0) {
if (httpResponse instanceof HttpContent &&
((HttpContent) httpResponse).content().readableBytes() < contentSizeThreshold) {
return null;
}
}
String contentEncoding = httpResponse.headers().get(HttpHeaderNames.CONTENT_ENCODING);
if (contentEncoding != null) {
// Content-Encoding was set, either as something specific or as the IDENTITY encoding
// Therefore, we should NOT encode here
return null;
}
ZlibWrapper wrapper = determineWrapper(acceptEncoding);
if (wrapper == null) {
return null;
}
String targetContentEncoding;
switch (wrapper) {
case GZIP:
targetContentEncoding = "gzip";
break;
case ZLIB:
targetContentEncoding = "deflate";
break;
default:
throw new Error();
}
return new Result(
targetContentEncoding,
new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(
wrapper, compressionLevel, windowBits, memLevel)));
}
@SuppressWarnings("FloatingPointEquality")
protected ZlibWrapper determineWrapper(String acceptEncoding) {
float starQ = -1.0f;
float gzipQ = -1.0f;
float deflateQ = -1.0f;
for (String encoding : acceptEncoding.split(",")) {
float q = 1.0f;
int equalsPos = encoding.indexOf('=');
if (equalsPos != -1) {
try {
q = Float.parseFloat(encoding.substring(equalsPos + 1));
} catch (NumberFormatException e) {
// Ignore encoding
q = 0.0f;
}
}
if (encoding.contains("*")) {
starQ = q;
} else if (encoding.contains("gzip") && q > gzipQ) {
gzipQ = q;
} else if (encoding.contains("deflate") && q > deflateQ) {
deflateQ = q;
}
}
if (gzipQ > 0.0f || deflateQ > 0.0f) {
if (gzipQ >= deflateQ) {
return ZlibWrapper.GZIP;
} else {
return ZlibWrapper.ZLIB;
}
}
if (starQ > 0.0f) {
if (gzipQ == -1.0f) {
return ZlibWrapper.GZIP;
}
if (deflateQ == -1.0f) {
return ZlibWrapper.ZLIB;
}
}
return null;
}
}
