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This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).
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/*
 * 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.Http2CodecUtil.DEFAULT_INITIAL_HUFFMAN_DECODE_CAPACITY;
import static io.netty.handler.codec.http2.Http2Error.COMPRESSION_ERROR;
import static io.netty.handler.codec.http2.Http2Error.INTERNAL_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;
    private long maxHeaderListSizeGoAway;

    /**
     * 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 SETTINGS_MAX_HEADER_LIST_SIZE
     *  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, DEFAULT_INITIAL_HUFFMAN_DECODE_CAPACITY);
    }

    /**
     * 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 SETTINGS_MAX_HEADER_LIST_SIZE
     *  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;
        this.maxHeaderListSizeGoAway =
                Http2CodecUtil.calculateMaxHeaderListSizeGoAway(hpackDecoder.getMaxHeaderListSize());
    }

    @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 {
        if (goAwayMax < max || goAwayMax < 0) {
            throw connectionError(INTERNAL_ERROR, "Header List Size GO_AWAY %d must be non-negative and >= %d",
                    goAwayMax, max);
        }
        hpackDecoder.setMaxHeaderListSize(max);
        this.maxHeaderListSizeGoAway = goAwayMax;
    }

    @Override
    public long maxHeaderListSize() {
        return hpackDecoder.getMaxHeaderListSize();
    }

    @Override
    public long maxHeaderListSizeGoAway() {
        return maxHeaderListSizeGoAway;
    }

    @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, validateHeaders);
            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 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);
    }
}