All Downloads are FREE. Search and download functionalities are using the official Maven repository.

io.netty.handler.codec.json.JsonObjectDecoder Maven / Gradle / Ivy

Go to download

Easy Redis Java client and Real-Time Data Platform. Valkey compatible. Sync/Async/RxJava3/Reactive API. Client side caching. Over 50 Redis based Java objects and services: JCache API, Apache Tomcat, Hibernate, Spring, Set, Multimap, SortedSet, Map, List, Queue, Deque, Semaphore, Lock, AtomicLong, Map Reduce, Bloom filter, Scheduler, RPC

There is a newer version: 3.40.2
Show newest version
/*
 * 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:
 *
 *   https://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.json;

import static io.netty.util.internal.ObjectUtil.checkPositive;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.CorruptedFrameException;
import io.netty.handler.codec.TooLongFrameException;
import io.netty.channel.ChannelPipeline;

import java.util.List;

/**
 * Splits a byte stream of JSON objects and arrays into individual objects/arrays and passes them up the
 * {@link ChannelPipeline}.
 * 

* The byte stream is expected to be in UTF-8 character encoding or ASCII. The current implementation * uses direct {@code byte} to {@code char} cast and then compares that {@code char} to a few low range * ASCII characters like {@code '{'}, {@code '['} or {@code '"'}. UTF-8 is not using low range [0..0x7F] * byte values for multibyte codepoint representations therefore fully supported by this implementation. *

* This class does not do any real parsing or validation. A sequence of bytes is considered a JSON object/array * if it contains a matching number of opening and closing braces/brackets. It's up to a subsequent * {@link ChannelHandler} to parse the JSON text into a more usable form i.e. a POJO. */ public class JsonObjectDecoder extends ByteToMessageDecoder { private static final int ST_CORRUPTED = -1; private static final int ST_INIT = 0; private static final int ST_DECODING_NORMAL = 1; private static final int ST_DECODING_ARRAY_STREAM = 2; private int openBraces; private int idx; private int lastReaderIndex; private int state; private boolean insideString; private final int maxObjectLength; private final boolean streamArrayElements; public JsonObjectDecoder() { // 1 MB this(1024 * 1024); } public JsonObjectDecoder(int maxObjectLength) { this(maxObjectLength, false); } public JsonObjectDecoder(boolean streamArrayElements) { this(1024 * 1024, streamArrayElements); } /** * @param maxObjectLength maximum number of bytes a JSON object/array may use (including braces and all). * Objects exceeding this length are dropped and an {@link TooLongFrameException} * is thrown. * @param streamArrayElements if set to true and the "top level" JSON object is an array, each of its entries * is passed through the pipeline individually and immediately after it was fully * received, allowing for arrays with "infinitely" many elements. * */ public JsonObjectDecoder(int maxObjectLength, boolean streamArrayElements) { this.maxObjectLength = checkPositive(maxObjectLength, "maxObjectLength"); this.streamArrayElements = streamArrayElements; } @Override protected void decode(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception { if (state == ST_CORRUPTED) { in.skipBytes(in.readableBytes()); return; } if (this.idx > in.readerIndex() && lastReaderIndex != in.readerIndex()) { this.idx = in.readerIndex() + (idx - lastReaderIndex); } // index of next byte to process. int idx = this.idx; int wrtIdx = in.writerIndex(); if (wrtIdx > maxObjectLength) { // buffer size exceeded maxObjectLength; discarding the complete buffer. in.skipBytes(in.readableBytes()); reset(); throw new TooLongFrameException( "object length exceeds " + maxObjectLength + ": " + wrtIdx + " bytes discarded"); } for (/* use current idx */; idx < wrtIdx; idx++) { byte c = in.getByte(idx); if (state == ST_DECODING_NORMAL) { decodeByte(c, in, idx); // All opening braces/brackets have been closed. That's enough to conclude // that the JSON object/array is complete. if (openBraces == 0) { ByteBuf json = extractObject(ctx, in, in.readerIndex(), idx + 1 - in.readerIndex()); if (json != null) { out.add(json); } // The JSON object/array was extracted => discard the bytes from // the input buffer. in.readerIndex(idx + 1); // Reset the object state to get ready for the next JSON object/text // coming along the byte stream. reset(); } } else if (state == ST_DECODING_ARRAY_STREAM) { decodeByte(c, in, idx); if (!insideString && (openBraces == 1 && c == ',' || openBraces == 0 && c == ']')) { // skip leading spaces. No range check is needed and the loop will terminate // because the byte at position idx is not a whitespace. for (int i = in.readerIndex(); Character.isWhitespace(in.getByte(i)); i++) { in.skipBytes(1); } // skip trailing spaces. int idxNoSpaces = idx - 1; while (idxNoSpaces >= in.readerIndex() && Character.isWhitespace(in.getByte(idxNoSpaces))) { idxNoSpaces--; } ByteBuf json = extractObject(ctx, in, in.readerIndex(), idxNoSpaces + 1 - in.readerIndex()); if (json != null) { out.add(json); } in.readerIndex(idx + 1); if (c == ']') { reset(); } } // JSON object/array detected. Accumulate bytes until all braces/brackets are closed. } else if (c == '{' || c == '[') { initDecoding(c); if (state == ST_DECODING_ARRAY_STREAM) { // Discard the array bracket in.skipBytes(1); } // Discard leading spaces in front of a JSON object/array. } else if (Character.isWhitespace(c)) { in.skipBytes(1); } else { state = ST_CORRUPTED; throw new CorruptedFrameException( "invalid JSON received at byte position " + idx + ": " + ByteBufUtil.hexDump(in)); } } if (in.readableBytes() == 0) { this.idx = 0; } else { this.idx = idx; } this.lastReaderIndex = in.readerIndex(); } /** * Override this method if you want to filter the json objects/arrays that get passed through the pipeline. */ @SuppressWarnings("UnusedParameters") protected ByteBuf extractObject(ChannelHandlerContext ctx, ByteBuf buffer, int index, int length) { return buffer.retainedSlice(index, length); } private void decodeByte(byte c, ByteBuf in, int idx) { if ((c == '{' || c == '[') && !insideString) { openBraces++; } else if ((c == '}' || c == ']') && !insideString) { openBraces--; } else if (c == '"') { // start of a new JSON string. It's necessary to detect strings as they may // also contain braces/brackets and that could lead to incorrect results. if (!insideString) { insideString = true; } else { int backslashCount = 0; idx--; while (idx >= 0) { if (in.getByte(idx) == '\\') { backslashCount++; idx--; } else { break; } } // The double quote isn't escaped only if there are even "\"s. if (backslashCount % 2 == 0) { // Since the double quote isn't escaped then this is the end of a string. insideString = false; } } } } private void initDecoding(byte openingBrace) { openBraces = 1; if (openingBrace == '[' && streamArrayElements) { state = ST_DECODING_ARRAY_STREAM; } else { state = ST_DECODING_NORMAL; } } private void reset() { insideString = false; state = ST_INIT; openBraces = 0; } }