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    • io.netty.handler.codec.http.HttpContentDecoder Maven / Gradle / Ivy

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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).

    There is a newer version: 35.0.0.Beta1
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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.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.CodecException;
import io.netty.handler.codec.MessageToMessageDecoder;
import io.netty.util.ReferenceCountUtil;

import java.util.List;

/**
 * Decodes the content of the received {@link HttpRequest} and {@link HttpContent}.
 * The original content is replaced with the new content decoded by the
 * {@link EmbeddedChannel}, which is created by {@link #newContentDecoder(String)}.
 * Once decoding is finished, the value of the 'Content-Encoding'
 * header is set to the target content encoding, as returned by {@link #getTargetContentEncoding(String)}.
 * Also, the 'Content-Length' header is updated to the length of the
 * decoded content.  If the content encoding of the original is not supported
 * by the decoder, {@link #newContentDecoder(String)} should return {@code null}
 * so that no decoding occurs (i.e. pass-through).
 * 
    
 * Please note that this is an abstract class.  You have to extend this class
 * and implement {@link #newContentDecoder(String)} properly to make this class
 * functional.  For example, refer to the source code of {@link HttpContentDecompressor}.
 * 
    
 * This handler must be placed after {@link HttpObjectDecoder} in the pipeline
 * so that this handler can intercept HTTP requests after {@link HttpObjectDecoder}
 * converts {@link ByteBuf}s into HTTP requests.
 */
public abstract class HttpContentDecoder extends MessageToMessageDecoder {

    private EmbeddedChannel decoder;
    private boolean continueResponse;

    @Override
    protected void decode(ChannelHandlerContext ctx, HttpObject msg, List out) throws Exception {
        if (msg instanceof HttpResponse && ((HttpResponse) msg).getStatus().code() == 100) {

            if (!(msg instanceof LastHttpContent)) {
                continueResponse = true;
            }
            // 100-continue response must be passed through.
            out.add(ReferenceCountUtil.retain(msg));
            return;
        }

        if (continueResponse) {
            if (msg instanceof LastHttpContent) {
                continueResponse = false;
            }
            // 100-continue response must be passed through.
            out.add(ReferenceCountUtil.retain(msg));
            return;
        }

        if (msg instanceof HttpMessage) {
            cleanup();
            final HttpMessage message = (HttpMessage) msg;
            final HttpHeaders headers = message.headers();

            // Determine the content encoding.
            String contentEncoding = headers.get(HttpHeaders.Names.CONTENT_ENCODING);
            if (contentEncoding != null) {
                contentEncoding = contentEncoding.trim();
            } else {
                contentEncoding = HttpHeaders.Values.IDENTITY;
            }
            decoder = newContentDecoder(contentEncoding);

            if (decoder == null) {
                if (message instanceof HttpContent) {
                    ((HttpContent) message).retain();
                }
                out.add(message);
                return;
            }

            // Remove content-length header:
            // the correct value can be set only after all chunks are processed/decoded.
            // If buffering is not an issue, add HttpObjectAggregator down the chain, it will set the header.
            // Otherwise, rely on LastHttpContent message.
            headers.remove(HttpHeaders.Names.CONTENT_LENGTH);

            // set new content encoding,
            CharSequence targetContentEncoding = getTargetContentEncoding(contentEncoding);
            if (HttpHeaders.Values.IDENTITY.equals(targetContentEncoding)) {
                // Do NOT set the 'Content-Encoding' header if the target encoding is 'identity'
                // as per: http://tools.ietf.org/html/rfc2616#section-14.11
                headers.remove(HttpHeaders.Names.CONTENT_ENCODING);
            } else {
                headers.set(HttpHeaders.Names.CONTENT_ENCODING, targetContentEncoding);
            }

            if (message instanceof HttpContent) {
                // If message is a full request or response object (headers + data), don't copy data part into out.
                // Output headers only; data part will be decoded below.
                // Note: "copy" object must not be an instance of LastHttpContent class,
                // as this would (erroneously) indicate the end of the HttpMessage to other handlers.
                HttpMessage copy;
                if (message instanceof HttpRequest) {
                    HttpRequest r = (HttpRequest) message; // HttpRequest or FullHttpRequest
                    copy = new DefaultHttpRequest(r.getProtocolVersion(), r.getMethod(), r.getUri());
                } else if (message instanceof HttpResponse) {
                    HttpResponse r = (HttpResponse) message; // HttpResponse or FullHttpResponse
                    copy = new DefaultHttpResponse(r.getProtocolVersion(), r.getStatus());
                } else {
                    throw new CodecException("Object of class " + message.getClass().getName() +
                                             " is not a HttpRequest or HttpResponse");
                }
                copy.headers().set(message.headers());
                copy.setDecoderResult(message.getDecoderResult());
                out.add(copy);
            } else {
                out.add(message);
            }
        }

        if (msg instanceof HttpContent) {
            final HttpContent c = (HttpContent) msg;
            if (decoder == null) {
                out.add(c.retain());
            } else {
                decodeContent(c, out);
            }
        }
    }

    private void decodeContent(HttpContent c, List out) {
        ByteBuf content = c.content();

        decode(content, out);

        if (c instanceof LastHttpContent) {
            finishDecode(out);

            LastHttpContent last = (LastHttpContent) c;
            // Generate an additional chunk if the decoder produced
            // the last product on closure,
            HttpHeaders headers = last.trailingHeaders();
            if (headers.isEmpty()) {
                out.add(LastHttpContent.EMPTY_LAST_CONTENT);
            } else {
                out.add(new ComposedLastHttpContent(headers));
            }
        }
    }

    /**
     * Returns a new {@link EmbeddedChannel} that decodes the HTTP message
     * content encoded in the specified contentEncoding.
     *
     * @param contentEncoding the value of the {@code "Content-Encoding"} header
     * @return a new {@link EmbeddedChannel} if the specified encoding is supported.
     *         {@code null} otherwise (alternatively, you can throw an exception
     *         to block unknown encoding).
     */
    protected abstract EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception;

    /**
     * Returns the expected content encoding of the decoded content.
     * This getMethod returns {@code "identity"} by default, which is the case for
     * most decoders.
     *
     * @param contentEncoding the value of the {@code "Content-Encoding"} header
     * @return the expected content encoding of the new content
     */
    protected String getTargetContentEncoding(
            @SuppressWarnings("UnusedParameters") String contentEncoding) throws Exception {
        return HttpHeaders.Values.IDENTITY;
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        cleanup();
        super.handlerRemoved(ctx);
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        cleanup();
        super.channelInactive(ctx);
    }

    private void cleanup() {
        if (decoder != null) {
            // Clean-up the previous decoder if not cleaned up correctly.
            if (decoder.finish()) {
                for (;;) {
                    ByteBuf buf = (ByteBuf) decoder.readInbound();
                    if (buf == null) {
                        break;
                    }
                    // Release the buffer
                    buf.release();
                }
            }
            decoder = null;
        }
    }

    private void decode(ByteBuf in, List out) {
        // call retain here as it will call release after its written to the channel
        decoder.writeInbound(in.retain());
        fetchDecoderOutput(out);
    }

    private void finishDecode(List out) {
        if (decoder.finish()) {
            fetchDecoderOutput(out);
        }
        decoder = null;
    }

    private void fetchDecoderOutput(List out) {
        for (;;) {
            ByteBuf buf = (ByteBuf) decoder.readInbound();
            if (buf == null) {
                break;
            }
            if (!buf.isReadable()) {
                buf.release();
                continue;
            }
            out.add(new DefaultHttpContent(buf));
        }
    }
}
    
    
    
    

    




    
    
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