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/* * Copyright 2002-2016 the original author or authors. * * Licensed 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 org.springframework.http.codec.json; import java.nio.charset.StandardCharsets; import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.function.Function; import io.netty.buffer.ByteBuf; import io.netty.buffer.ByteBufUtil; import io.netty.buffer.Unpooled; import org.reactivestreams.Publisher; import reactor.core.publisher.Flux; import org.springframework.core.ResolvableType; import org.springframework.core.codec.AbstractDecoder; import org.springframework.core.io.buffer.DataBuffer; import org.springframework.core.io.buffer.DataBufferFactory; import org.springframework.core.io.buffer.DataBufferUtils; import org.springframework.util.MimeType; /** * Decode an arbitrary split byte stream representing JSON objects to a byte * stream where each chunk is a well-formed JSON object. * * <p>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. * * <p>Based on <a href="https://github.com/netty/netty/blob/master/codec/src/main/java/io/netty/handler/codec/json/JsonObjectDecoder.java">Netty JsonObjectDecoder</a> * * @author Sebastien Deleuze * @since 5.0 */ class JsonObjectDecoder extends AbstractDecoder<DataBuffer> { 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 final int maxObjectLength; private final boolean streamArrayElements; public JsonObjectDecoder() { // 1 MB this(1024 * 1024); } public JsonObjectDecoder(int maxObjectLength) { this(maxObjectLength, true); } 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 IllegalStateException} 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 */ public JsonObjectDecoder(int maxObjectLength, boolean streamArrayElements) { super(new MimeType("application", "json", StandardCharsets.UTF_8), new MimeType("application", "*+json", StandardCharsets.UTF_8)); if (maxObjectLength < 1) { throw new IllegalArgumentException("maxObjectLength must be a positive int"); } this.maxObjectLength = maxObjectLength; this.streamArrayElements = streamArrayElements; } @Override public Flux<DataBuffer> decode(Publisher<DataBuffer> inputStream, ResolvableType elementType, MimeType mimeType, Map<String, Object> hints) { return Flux.from(inputStream).flatMap(new Function<DataBuffer, Publisher<? extends DataBuffer>>() { int openBraces; int index; int state; boolean insideString; ByteBuf input; Integer writerIndex; @Override public Publisher<? extends DataBuffer> apply(DataBuffer buffer) { List<DataBuffer> chunks = new ArrayList<>(); if (this.input == null) { this.input = Unpooled.copiedBuffer(buffer.asByteBuffer()); DataBufferUtils.release(buffer); this.writerIndex = this.input.writerIndex(); } else { this.index = this.index - this.input.readerIndex(); this.input = Unpooled.copiedBuffer(this.input, Unpooled.copiedBuffer(buffer.asByteBuffer())); DataBufferUtils.release(buffer); this.writerIndex = this.input.writerIndex(); } if (this.state == ST_CORRUPTED) { this.input.skipBytes(this.input.readableBytes()); return Flux.error(new IllegalStateException("Corrupted stream")); } if (this.writerIndex > maxObjectLength) { // buffer size exceeded maxObjectLength; discarding the complete buffer. this.input.skipBytes(this.input.readableBytes()); reset(); return Flux.error(new IllegalStateException("object length exceeds " + maxObjectLength + ": " + this.writerIndex + " bytes discarded")); } DataBufferFactory dataBufferFactory = buffer.factory(); for (/* use current index */; this.index < this.writerIndex; this.index++) { byte c = this.input.getByte(this.index); if (this.state == ST_DECODING_NORMAL) { decodeByte(c, this.input, this.index); // All opening braces/brackets have been closed. That's enough to conclude // that the JSON object/array is complete. if (this.openBraces == 0) { ByteBuf json = extractObject(this.input, this.input.readerIndex(), this.index + 1 - this.input.readerIndex()); if (json != null) { chunks.add(dataBufferFactory.wrap(json.nioBuffer())); } // The JSON object/array was extracted => discard the bytes from // the input buffer. this.input.readerIndex(this.index + 1); // Reset the object state to get ready for the next JSON object/text // coming along the byte stream. reset(); } } else if (this.state == ST_DECODING_ARRAY_STREAM) { decodeByte(c, this.input, this.index); if (!this.insideString && (this.openBraces == 1 && c == ',' || this.openBraces == 0 && c == ']')) { // skip leading spaces. No range check is needed and the loop will terminate // because the byte at position index is not a whitespace. for (int i = this.input.readerIndex(); Character .isWhitespace(this.input.getByte(i)); i++) { this.input.skipBytes(1); } // skip trailing spaces. int idxNoSpaces = this.index - 1; while (idxNoSpaces >= this.input.readerIndex() && Character.isWhitespace(this.input.getByte(idxNoSpaces))) { idxNoSpaces--; } ByteBuf json = extractObject(this.input, this.input.readerIndex(), idxNoSpaces + 1 - this.input.readerIndex()); if (json != null) { chunks.add(dataBufferFactory.wrap(json.nioBuffer())); } this.input.readerIndex(this.index + 1); if (c == ']') { reset(); } } // JSON object/array detected. Accumulate bytes until all braces/brackets are closed. } else if (c == '{' || c == '[') { initDecoding(c, streamArrayElements); if (this.state == ST_DECODING_ARRAY_STREAM) { // Discard the array bracket this.input.skipBytes(1); } // Discard leading spaces in front of a JSON object/array. } else if (Character.isWhitespace(c)) { this.input.skipBytes(1); } else { this.state = ST_CORRUPTED; return Flux.error(new IllegalStateException("invalid JSON received at byte position " + this.index + ": " + ByteBufUtil.hexDump(this.input))); } } return Flux.fromIterable(chunks); } /** * Override this method if you want to filter the json objects/arrays that * get passed through the pipeline. */ protected ByteBuf extractObject(ByteBuf buffer, int index, int length) { return buffer.slice(index, length).retain(); } private void decodeByte(byte c, ByteBuf input, int index) { if ((c == '{' || c == '[') && !this.insideString) { this.openBraces++; } else if ((c == '}' || c == ']') && !this.insideString) { this.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 (!this.insideString) { this.insideString = true; // If the double quote wasn't escaped then this is the end of a string. } else if (input.getByte(index - 1) != '\\') { this.insideString = false; } } } private void initDecoding(byte openingBrace, boolean streamArrayElements) { this.openBraces = 1; if (openingBrace == '[' && streamArrayElements) { this.state = ST_DECODING_ARRAY_STREAM; } else { this.state = ST_DECODING_NORMAL; } } private void reset() { this.insideString = false; this.state = ST_INIT; this.openBraces = 0; } }); } }