/*
* 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.stomp;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.DecoderException;
import io.netty.handler.codec.DecoderResult;
import io.netty.handler.codec.ReplayingDecoder;
import io.netty.handler.codec.TooLongFrameException;
import io.netty.handler.codec.stomp.StompSubframeDecoder.State;
import io.netty.util.internal.AppendableCharSequence;
import java.util.List;
import java.util.Locale;
import static io.netty.buffer.ByteBufUtil.indexOf;
import static io.netty.buffer.ByteBufUtil.readBytes;
/**
* Decodes {@link ByteBuf}s into {@link StompHeadersSubframe}s and
* {@link StompContentSubframe}s.
*
* <h3>Parameters to control memory consumption: </h3>
* {@code maxLineLength} the maximum length of line -
* restricts length of command and header lines
* If the length of the initial line exceeds this value, a
* {@link TooLongFrameException} will be raised.
* <br>
* {@code maxChunkSize}
* The maximum length of the content or each chunk. If the content length
* (or the length of each chunk) exceeds this value, the content or chunk
* ill be split into multiple {@link StompContentSubframe}s whose length is
* {@code maxChunkSize} at maximum.
*
* <h3>Chunked Content</h3>
*
* If the content of a stomp message is greater than {@code maxChunkSize}
* the transfer encoding of the HTTP message is 'chunked', this decoder
* generates multiple {@link StompContentSubframe} instances to avoid excessive memory
* consumption. Note, that every message, even with no content decodes with
* {@link LastStompContentSubframe} at the end to simplify upstream message parsing.
*/
public class StompSubframeDecoder extends ReplayingDecoder<State> {
private static final int DEFAULT_CHUNK_SIZE = 8132;
private static final int DEFAULT_MAX_LINE_LENGTH = 1024;
enum State {
SKIP_CONTROL_CHARACTERS,
READ_HEADERS,
READ_CONTENT,
FINALIZE_FRAME_READ,
BAD_FRAME,
INVALID_CHUNK
}
private final int maxLineLength;
private final int maxChunkSize;
private int alreadyReadChunkSize;
private LastStompContentSubframe lastContent;
private long contentLength = -1;
public StompSubframeDecoder() {
this(DEFAULT_MAX_LINE_LENGTH, DEFAULT_CHUNK_SIZE);
}
public StompSubframeDecoder(int maxLineLength, int maxChunkSize) {
super(State.SKIP_CONTROL_CHARACTERS);
if (maxLineLength <= 0) {
throw new IllegalArgumentException(
"maxLineLength must be a positive integer: " +
maxLineLength);
}
if (maxChunkSize <= 0) {
throw new IllegalArgumentException(
"maxChunkSize must be a positive integer: " +
maxChunkSize);
}
this.maxChunkSize = maxChunkSize;
this.maxLineLength = maxLineLength;
}
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
switch (state()) {
case SKIP_CONTROL_CHARACTERS:
skipControlCharacters(in);
checkpoint(State.READ_HEADERS);
// Fall through.
case READ_HEADERS:
StompCommand command = StompCommand.UNKNOWN;
StompHeadersSubframe frame = null;
try {
command = readCommand(in);
frame = new DefaultStompHeadersSubframe(command);
checkpoint(readHeaders(in, frame.headers()));
out.add(frame);
} catch (Exception e) {
if (frame == null) {
frame = new DefaultStompHeadersSubframe(command);
}
frame.setDecoderResult(DecoderResult.failure(e));
out.add(frame);
checkpoint(State.BAD_FRAME);
return;
}
break;
case BAD_FRAME:
in.skipBytes(actualReadableBytes());
return;
}
try {
switch (state()) {
case READ_CONTENT:
int toRead = in.readableBytes();
if (toRead == 0) {
return;
}
if (toRead > maxChunkSize) {
toRead = maxChunkSize;
}
if (this.contentLength >= 0) {
int remainingLength = (int) (contentLength - alreadyReadChunkSize);
if (toRead > remainingLength) {
toRead = remainingLength;
}
ByteBuf chunkBuffer = readBytes(ctx.alloc(), in, toRead);
if ((alreadyReadChunkSize += toRead) >= contentLength) {
lastContent = new DefaultLastStompContentSubframe(chunkBuffer);
checkpoint(State.FINALIZE_FRAME_READ);
} else {
out.add(new DefaultStompContentSubframe(chunkBuffer));
return;
}
} else {
int nulIndex = indexOf(in, in.readerIndex(), in.writerIndex(), StompConstants.NUL);
if (nulIndex == in.readerIndex()) {
checkpoint(State.FINALIZE_FRAME_READ);
} else {
if (nulIndex > 0) {
toRead = nulIndex - in.readerIndex();
} else {
toRead = in.writerIndex() - in.readerIndex();
}
ByteBuf chunkBuffer = readBytes(ctx.alloc(), in, toRead);
alreadyReadChunkSize += toRead;
if (nulIndex > 0) {
lastContent = new DefaultLastStompContentSubframe(chunkBuffer);
checkpoint(State.FINALIZE_FRAME_READ);
} else {
out.add(new DefaultStompContentSubframe(chunkBuffer));
return;
}
}
}
// Fall through.
case FINALIZE_FRAME_READ:
skipNullCharacter(in);
if (lastContent == null) {
lastContent = LastStompContentSubframe.EMPTY_LAST_CONTENT;
}
out.add(lastContent);
resetDecoder();
}
} catch (Exception e) {
StompContentSubframe errorContent = new DefaultLastStompContentSubframe(Unpooled.EMPTY_BUFFER);
errorContent.setDecoderResult(DecoderResult.failure(e));
out.add(errorContent);
checkpoint(State.BAD_FRAME);
}
}
private StompCommand readCommand(ByteBuf in) {
String commandStr = readLine(in, maxLineLength);
StompCommand command = null;
try {
command = StompCommand.valueOf(commandStr);
} catch (IllegalArgumentException iae) {
//do nothing
}
if (command == null) {
commandStr = commandStr.toUpperCase(Locale.US);
try {
command = StompCommand.valueOf(commandStr);
} catch (IllegalArgumentException iae) {
//do nothing
}
}
if (command == null) {
throw new DecoderException("failed to read command from channel");
}
return command;
}
private State readHeaders(ByteBuf buffer, StompHeaders headers) {
for (;;) {
String line = readLine(buffer, maxLineLength);
if (!line.isEmpty()) {
String[] split = line.split(":");
if (split.length == 2) {
headers.add(split[0], split[1]);
}
} else {
if (headers.contains(StompHeaders.CONTENT_LENGTH)) {
this.contentLength = getContentLength(headers, 0);
if (this.contentLength == 0) {
return State.FINALIZE_FRAME_READ;
}
}
return State.READ_CONTENT;
}
}
}
private static long getContentLength(StompHeaders headers, long defaultValue) {
long contentLength = headers.getLong(StompHeaders.CONTENT_LENGTH, defaultValue);
if (contentLength < 0) {
throw new DecoderException(StompHeaders.CONTENT_LENGTH + " must be non-negative");
}
return contentLength;
}
private static void skipNullCharacter(ByteBuf buffer) {
byte b = buffer.readByte();
if (b != StompConstants.NUL) {
throw new IllegalStateException("unexpected byte in buffer " + b + " while expecting NULL byte");
}
}
private static void skipControlCharacters(ByteBuf buffer) {
byte b;
for (;;) {
b = buffer.readByte();
if (b != StompConstants.CR && b != StompConstants.LF) {
buffer.readerIndex(buffer.readerIndex() - 1);
break;
}
}
}
private static String readLine(ByteBuf buffer, int maxLineLength) {
AppendableCharSequence buf = new AppendableCharSequence(128);
int lineLength = 0;
for (;;) {
byte nextByte = buffer.readByte();
if (nextByte == StompConstants.CR) {
nextByte = buffer.readByte();
if (nextByte == StompConstants.LF) {
return buf.toString();
}
} else if (nextByte == StompConstants.LF) {
return buf.toString();
} else {
if (lineLength >= maxLineLength) {
throw new TooLongFrameException("An STOMP line is larger than " + maxLineLength + " bytes.");
}
lineLength ++;
buf.append((char) nextByte);
}
}
}
private void resetDecoder() {
checkpoint(State.SKIP_CONTROL_CHARACTERS);
contentLength = -1;
alreadyReadChunkSize = 0;
lastContent = null;
}
}