Split a JSON byte stream into JSON objects/arrays. Fixes #2536
Motivation: See GitHub Issue #2536. Modifications: Introduce the class JsonObjectDecoder to split a JSON byte stream into individual JSON objets/arrays. Result: A Netty application can now handle a byte stream where multiple JSON documents follow eachother as opposed to only a single JSON document per request.
This commit is contained in:
Jakob Buchgraber
Trustin Lee
parent
10623ae133
commit
aed13ba5ef
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/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.json;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.ByteBufUtil;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.ByteToMessageDecoder;
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import io.netty.channel.ChannelHandler;
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import io.netty.handler.codec.CorruptedFrameException;
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import io.netty.handler.codec.TooLongFrameException;
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import io.netty.channel.ChannelPipeline;
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import java.util.List;
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/**
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* Splits a byte stream of JSON objects and arrays into individual objects/arrays and passes them up the
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* {@link ChannelPipeline}.
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*
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* This class does not do any real parsing or validation. A sequence of bytes is considered a JSON object/array
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* if it contains a matching number of opening and closing braces/brackets. It's up to a subsequent
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* {@link ChannelHandler} to parse the JSON text into a more usable form i.e. a POJO.
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*/
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public class JsonObjectDecoder extends ByteToMessageDecoder {
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private int openBraces;
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private int idx;
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private boolean isDecoding;
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private boolean isArrayStreamDecoding;
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private boolean insideString;
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private final int maxObjectLength;
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private final boolean streamArrayElements;
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public JsonObjectDecoder() {
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// 1 MB
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this(1024 * 1024);
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}
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public JsonObjectDecoder(int maxObjectLength) {
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this(maxObjectLength, false);
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}
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public JsonObjectDecoder(boolean streamArrayElements) {
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this(1024 * 1024, streamArrayElements);
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}
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/**
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* @param maxObjectLength maximum number of bytes a JSON object/array may use (including braces and all).
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* Objects exceeding this length are dropped and an {@link TooLongFrameException}
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* is thrown.
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* @param streamArrayElements if set to true and the "top level" JSON object is an array, each of its entries
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* is passed through the pipeline individually and immediately after it was fully
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* received, allowing for arrays with "infinitely" many elements.
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*
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*/
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public JsonObjectDecoder(int maxObjectLength, boolean streamArrayElements) {
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if (maxObjectLength < 1) {
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throw new IllegalArgumentException("maxObjectLength must be a positive int");
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}
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this.maxObjectLength = maxObjectLength;
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this.streamArrayElements = streamArrayElements;
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}
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@Override
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protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
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// index of next byte to process.
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int idx = this.idx;
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int wrtIdx = in.writerIndex();
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if (wrtIdx > maxObjectLength) {
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// buffer size exceeded maxObjectLength; discarding the complete buffer.
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ctx.fireExceptionCaught(
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new TooLongFrameException(
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"object length exceeds " + maxObjectLength + ": " + wrtIdx + " bytes discarded")
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);
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in.skipBytes(in.readableBytes());
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reset();
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return;
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}
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for (/* use current idx */; idx < wrtIdx; idx++) {
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byte c = in.getByte(idx);
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if (isDecoding) {
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decodeByte(c, in, idx);
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// All opening braces/brackets have been closed. That's enough to conclude
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// that the JSON object/array is complete.
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if (openBraces == 0) {
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ByteBuf json = extractObject(ctx, in, in.readerIndex(), idx + 1 - in.readerIndex());
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if (json != null) {
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out.add(json);
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}
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// The JSON object/array was extracted => discard the bytes from
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// the input buffer.
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in.readerIndex(idx + 1);
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// Reset the object state to get ready for the next JSON object/text
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// coming along the byte stream.
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reset();
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}
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} else if (isArrayStreamDecoding) {
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decodeByte(c, in, idx);
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if (!insideString && (openBraces == 1 && c == ',' || openBraces == 0 && c == ']')) {
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// skip leading spaces. No range check is needed and the loop will terminate
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// because the byte at position idx is not a whitespace.
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for (int i = in.readerIndex(); Character.isWhitespace(in.getByte(i)); i++) {
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in.skipBytes(1);
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}
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// skip trailing spaces.
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int idxNoSpaces = idx - 1;
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while (idxNoSpaces >= in.readerIndex() && Character.isWhitespace(in.getByte(idxNoSpaces))) {
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idxNoSpaces--;
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}
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ByteBuf json = extractObject(ctx, in, in.readerIndex(), idxNoSpaces + 1 - in.readerIndex());
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if (json != null) {
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out.add(json);
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}
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in.readerIndex(idx + 1);
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if (c == ']') {
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reset();
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}
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}
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// JSON object/array detected. Accumulate bytes until all braces/brackets are closed.
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} else if (c == '{' || c == '[') {
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initDecoding(c);
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if (isArrayStreamDecoding) {
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// Discard the array bracket
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in.skipBytes(1);
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}
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// Discard leading spaces in front of a JSON object/array.
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} else if (Character.isWhitespace(c)) {
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in.skipBytes(1);
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} else {
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ctx.fireExceptionCaught(
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new CorruptedFrameException("Invalid JSON received at byte position " + idx + ". " +
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"Hexdump: " + ByteBufUtil.hexDump(in)));
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}
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}
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if (in.readableBytes() == 0) {
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this.idx = 0;
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} else {
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this.idx = idx;
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}
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}
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/**
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* Override this method if you want to filter the json objects/arrays that get passed through the pipeline.
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*/
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protected ByteBuf extractObject(ChannelHandlerContext ctx, ByteBuf buffer, int index, int length) {
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return buffer.slice(index, length).retain();
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}
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private void decodeByte(byte c, ByteBuf in, int idx) {
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if ((c == '{' || c == '[') && !insideString) {
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openBraces++;
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} else if ((c == '}' || c == ']') && !insideString) {
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openBraces--;
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} else if (c == '"') {
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// start of a new JSON string. It's necessary to detect strings as they may
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// also contain braces/brackets and that could lead to incorrect results.
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if (!insideString) {
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insideString = true;
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// If the double quote wasn't escaped then this is the end of a string.
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} else if (in.getByte(idx - 1) != '\\') {
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insideString = false;
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}
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}
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}
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private void initDecoding(byte openingBrace) {
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openBraces = 1;
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isArrayStreamDecoding = openingBrace == '[' && streamArrayElements;
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isDecoding = !isArrayStreamDecoding;
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}
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private void reset() {
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isDecoding = insideString = isArrayStreamDecoding = false;
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openBraces = 0;
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}
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}
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@ -0,0 +1,20 @@
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/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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/**
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* <a href="http://en.wikipedia.org/wiki/JSON">JSON</a> specific codecs.
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*/
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package io.netty.handler.codec.json;
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@ -0,0 +1,223 @@
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/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.json;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.embedded.EmbeddedChannel;
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import io.netty.handler.codec.CorruptedFrameException;
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import io.netty.handler.codec.TooLongFrameException;
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import io.netty.util.CharsetUtil;
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import org.junit.Test;
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import java.nio.charset.Charset;
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import static org.junit.Assert.*;
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public class JsonObjectDecoderTest {
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@Test
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public void testJsonObjectOverMultipleWrites() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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String objectPart1 = "{ \"firstname\": \"John";
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String objectPart2 = "\" ,\n \"surname\" :";
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String objectPart3 = "\"Doe\", age:22 \n}";
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// Test object
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ch.writeInbound(Unpooled.copiedBuffer(" \n\n " + objectPart1, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(objectPart2, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(objectPart3 + " \n\n \n", CharsetUtil.UTF_8));
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ByteBuf res = ch.readInbound();
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assertEquals(objectPart1 + objectPart2 + objectPart3, res.toString(CharsetUtil.UTF_8));
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res.release();
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assertFalse(ch.finish());
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}
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@Test
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public void testJsonArrayOverMultipleWrites() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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String arrayPart1 = "[{\"test";
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String arrayPart2 = "case\" : \"\\\"}]Escaped dou\\\"ble quotes \\\" in JSON str\\\"ing\"";
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String arrayPart3 = " }\n\n , ";
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String arrayPart4 = "{\"testcase\" : \"Streaming string me";
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String arrayPart5 = "ssage\"} ]";
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// Test array
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ch.writeInbound(Unpooled.copiedBuffer(" " + arrayPart1, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(arrayPart2, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(arrayPart3, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(arrayPart4, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(arrayPart5 + " ", CharsetUtil.UTF_8));
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ByteBuf res = ch.readInbound();
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assertEquals(arrayPart1 + arrayPart2 + arrayPart3 + arrayPart4 + arrayPart5, res.toString(CharsetUtil.UTF_8));
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res.release();
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assertFalse(ch.finish());
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}
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@Test
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public void testSingleByteStream() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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String json = "{\"foo\" : {\"bar\" : [{},{}]}}";
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for (byte c : json.getBytes(CharsetUtil.UTF_8)) {
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ch.writeInbound(Unpooled.copiedBuffer(new byte[] {c}));
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}
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ByteBuf res = ch.readInbound();
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assertEquals(json, res.toString(CharsetUtil.UTF_8));
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res.release();
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assertFalse(ch.finish());
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}
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@Test
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public void testMultipleJsonObjectsInOneWrite() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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String object1 = "{\"key\" : \"value1\"}",
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object2 = "{\"key\" : \"value2\"}",
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object3 = "{\"key\" : \"value3\"}";
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ch.writeInbound(Unpooled.copiedBuffer(object1 + object2 + object3, CharsetUtil.UTF_8));
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ByteBuf res = ch.readInbound();
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assertEquals(object1, res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals(object2, res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals(object3, res.toString(CharsetUtil.UTF_8));
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res.release();
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assertFalse(ch.finish());
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}
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@Test(expected = CorruptedFrameException.class)
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public void testNonJsonContent1() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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ch.writeInbound(Unpooled.copiedBuffer(" b [1,2,3]", CharsetUtil.UTF_8));
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fail();
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}
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@Test(expected = CorruptedFrameException.class)
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public void testNonJsonContent2() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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ch.writeInbound(Unpooled.copiedBuffer(" [1,2,3] ", CharsetUtil.UTF_8));
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ByteBuf res = ch.readInbound();
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assertEquals("[1,2,3]", res.toString(CharsetUtil.UTF_8));
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res.release();
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ch.writeInbound(Unpooled.copiedBuffer(" a {\"key\" : 10}", CharsetUtil.UTF_8));
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fail();
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}
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@Test (expected = TooLongFrameException.class)
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public void testMaxObjectLength() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder(6));
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ch.writeInbound(Unpooled.copiedBuffer("[2,4,5]", CharsetUtil.UTF_8));
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fail();
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}
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@Test
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public void testOneJsonObjectPerWrite() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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String object1 = "{\"key\" : \"value1\"}",
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object2 = "{\"key\" : \"value2\"}",
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object3 = "{\"key\" : \"value3\"}";
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ch.writeInbound(Unpooled.copiedBuffer(object1, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(object2, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(object3, CharsetUtil.UTF_8));
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ByteBuf res = ch.readInbound();
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assertEquals(object1, res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals(object2, res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals(object3, res.toString(CharsetUtil.UTF_8));
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res.release();
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assertFalse(ch.finish());
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}
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@Test
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public void testSpecialJsonCharsInString() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder());
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String object = "{ \"key\" : \"[]{}}\\\"}}'}\"}";
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ch.writeInbound(Unpooled.copiedBuffer(object, CharsetUtil.UTF_8));
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ByteBuf res = ch.readInbound();
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assertEquals(object, res.toString(CharsetUtil.UTF_8));
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assertFalse(ch.finish());
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}
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@Test
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public void testStreamArrayElementsSimple() {
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EmbeddedChannel ch = new EmbeddedChannel(new JsonObjectDecoder(Integer.MAX_VALUE, true));
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String array = "[ 12, \"bla\" , 13.4 \t ,{\"key0\" : [1,2], \"key1\" : 12, \"key2\" : {}} , " +
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"true, false, null, [\"bla\", {}, [1,2,3]] ]";
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String object = "{\"bla\" : \"blub\"}";
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ch.writeInbound(Unpooled.copiedBuffer(array, CharsetUtil.UTF_8));
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ch.writeInbound(Unpooled.copiedBuffer(object, CharsetUtil.UTF_8));
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ByteBuf res = ch.readInbound();
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assertEquals("12", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals("\"bla\"", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals("13.4", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals("{\"key0\" : [1,2], \"key1\" : 12, \"key2\" : {}}", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals("true", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals("false", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals("null", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals("[\"bla\", {}, [1,2,3]]", res.toString(CharsetUtil.UTF_8));
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res.release();
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res = ch.readInbound();
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assertEquals(object, res.toString(CharsetUtil.UTF_8));
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res.release();
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assertFalse(ch.finish());
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}
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}
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