/*
* 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.util.internal.ObjectUtil;
import io.netty.util.internal.UnstableApi;
import static io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_HEADER_LIST_SIZE;
import static io.netty.handler.codec.http2.Http2Error.COMPRESSION_ERROR;
import static io.netty.handler.codec.http2.Http2Exception.connectionError;
@UnstableApi
public class DefaultHttp2HeadersDecoder implements Http2HeadersDecoder, Http2HeadersDecoder.Configuration {
private static final float HEADERS_COUNT_WEIGHT_NEW = 1 / 5f;
private static final float HEADERS_COUNT_WEIGHT_HISTORICAL = 1 - HEADERS_COUNT_WEIGHT_NEW;
private final HpackDecoder hpackDecoder;
private final boolean validateHeaders;
/**
* Used to calculate an exponential moving average of header sizes to get an estimate of how large the data
* structure for storing headers should be.
*/
private float headerArraySizeAccumulator = 8;
public DefaultHttp2HeadersDecoder() {
this(true);
}
public DefaultHttp2HeadersDecoder(boolean validateHeaders) {
this(validateHeaders, DEFAULT_HEADER_LIST_SIZE);
}
/**
* Create a new instance.
* @param validateHeaders {@code true} to validate headers are valid according to the RFC.
* @param maxHeaderListSize This is the only setting that can be configured before notifying the peer.
* This is because <a href="https://tools.ietf.org/html/rfc7540#section-6.5.1">SETTINGS_MAX_HEADER_LIST_SIZE</a>
* allows a lower than advertised limit from being enforced, and the default limit is unlimited
* (which is dangerous).
*/
public DefaultHttp2HeadersDecoder(boolean validateHeaders, long maxHeaderListSize) {
this(validateHeaders, maxHeaderListSize, 32);
}
/**
* Create a new instance.
* @param validateHeaders {@code true} to validate headers are valid according to the RFC.
* @param maxHeaderListSize This is the only setting that can be configured before notifying the peer.
* This is because <a href="https://tools.ietf.org/html/rfc7540#section-6.5.1">SETTINGS_MAX_HEADER_LIST_SIZE</a>
* allows a lower than advertised limit from being enforced, and the default limit is unlimited
* (which is dangerous).
* @param initialHuffmanDecodeCapacity Size of an intermediate buffer used during huffman decode.
*/
public DefaultHttp2HeadersDecoder(boolean validateHeaders, long maxHeaderListSize,
int initialHuffmanDecodeCapacity) {
this(validateHeaders, new HpackDecoder(maxHeaderListSize, initialHuffmanDecodeCapacity));
}
/**
* Exposed Used for testing only! Default values used in the initial settings frame are overridden intentionally
* for testing but violate the RFC if used outside the scope of testing.
*/
DefaultHttp2HeadersDecoder(boolean validateHeaders, HpackDecoder hpackDecoder) {
this.hpackDecoder = ObjectUtil.checkNotNull(hpackDecoder, "hpackDecoder");
this.validateHeaders = validateHeaders;
}
@Override
public void maxHeaderTableSize(long max) throws Http2Exception {
hpackDecoder.setMaxHeaderTableSize(max);
}
@Override
public long maxHeaderTableSize() {
return hpackDecoder.getMaxHeaderTableSize();
}
@Override
public void maxHeaderListSize(long max, long goAwayMax) throws Http2Exception {
hpackDecoder.setMaxHeaderListSize(max, goAwayMax);
}
@Override
public long maxHeaderListSize() {
return hpackDecoder.getMaxHeaderListSize();
}
@Override
public long maxHeaderListSizeGoAway() {
return hpackDecoder.getMaxHeaderListSizeGoAway();
}
@Override
public Configuration configuration() {
return this;
}
@Override
public Http2Headers decodeHeaders(int streamId, ByteBuf headerBlock) throws Http2Exception {
try {
final Http2Headers headers = newHeaders();
hpackDecoder.decode(streamId, headerBlock, headers);
headerArraySizeAccumulator = HEADERS_COUNT_WEIGHT_NEW * headers.size() +
HEADERS_COUNT_WEIGHT_HISTORICAL * headerArraySizeAccumulator;
return headers;
} catch (Http2Exception e) {
throw e;
} catch (Throwable e) {
// Default handler for any other types of errors that may have occurred. For example,
// the the Header builder throws IllegalArgumentException if the key or value was invalid
// for any reason (e.g. the key was an invalid pseudo-header).
throw connectionError(COMPRESSION_ERROR, e, e.getMessage());
}
}
/**
* A weighted moving average estimating how many headers are expected during the decode process.
* @return an estimate of how many headers are expected during the decode process.
*/
protected final int numberOfHeadersGuess() {
return (int) headerArraySizeAccumulator;
}
/**
* Determines if the headers should be validated as a result of the decode operation.
* @return {@code true} if the headers should be validated as a result of the decode operation.
*/
protected final boolean validateHeaders() {
return validateHeaders;
}
/**
* Create a new {@link Http2Headers} object which will store the results of the decode operation.
* @return a new {@link Http2Headers} object which will store the results of the decode operation.
*/
protected Http2Headers newHeaders() {
return new DefaultHttp2Headers(validateHeaders, (int) headerArraySizeAccumulator);
}
}