StompSubframeEncoder.java
/*
* 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.stomp;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageEncoder;
import io.netty.util.concurrent.FastThreadLocal;
import io.netty.util.internal.AppendableCharSequence;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map.Entry;
import static io.netty.handler.codec.stomp.StompConstants.NUL;
import static io.netty.handler.codec.stomp.StompHeaders.ACCEPT_VERSION;
import static io.netty.handler.codec.stomp.StompHeaders.ACK;
import static io.netty.handler.codec.stomp.StompHeaders.CONTENT_LENGTH;
import static io.netty.handler.codec.stomp.StompHeaders.CONTENT_TYPE;
import static io.netty.handler.codec.stomp.StompHeaders.DESTINATION;
import static io.netty.handler.codec.stomp.StompHeaders.HEART_BEAT;
import static io.netty.handler.codec.stomp.StompHeaders.HOST;
import static io.netty.handler.codec.stomp.StompHeaders.ID;
import static io.netty.handler.codec.stomp.StompHeaders.LOGIN;
import static io.netty.handler.codec.stomp.StompHeaders.MESSAGE;
import static io.netty.handler.codec.stomp.StompHeaders.MESSAGE_ID;
import static io.netty.handler.codec.stomp.StompHeaders.PASSCODE;
import static io.netty.handler.codec.stomp.StompHeaders.RECEIPT;
import static io.netty.handler.codec.stomp.StompHeaders.RECEIPT_ID;
import static io.netty.handler.codec.stomp.StompHeaders.SERVER;
import static io.netty.handler.codec.stomp.StompHeaders.SESSION;
import static io.netty.handler.codec.stomp.StompHeaders.SUBSCRIPTION;
import static io.netty.handler.codec.stomp.StompHeaders.TRANSACTION;
import static io.netty.handler.codec.stomp.StompHeaders.VERSION;
/**
* Encodes a {@link StompFrame} or a {@link StompSubframe} into a {@link ByteBuf}.
*/
public class StompSubframeEncoder extends MessageToMessageEncoder<StompSubframe> {
private static final int ESCAPE_HEADER_KEY_CACHE_LIMIT = 32;
private static final float DEFAULT_LOAD_FACTOR = 0.75f;
private static final FastThreadLocal<LinkedHashMap<CharSequence, CharSequence>> ESCAPE_HEADER_KEY_CACHE =
new FastThreadLocal<LinkedHashMap<CharSequence, CharSequence>>() {
@Override
protected LinkedHashMap<CharSequence, CharSequence> initialValue() throws Exception {
LinkedHashMap<CharSequence, CharSequence> cache = new LinkedHashMap<CharSequence, CharSequence>(
ESCAPE_HEADER_KEY_CACHE_LIMIT, DEFAULT_LOAD_FACTOR, true) {
@Override
protected boolean removeEldestEntry(Entry eldest) {
return size() > ESCAPE_HEADER_KEY_CACHE_LIMIT;
}
};
cache.put(ACCEPT_VERSION, ACCEPT_VERSION);
cache.put(HOST, HOST);
cache.put(LOGIN, LOGIN);
cache.put(PASSCODE, PASSCODE);
cache.put(HEART_BEAT, HEART_BEAT);
cache.put(VERSION, VERSION);
cache.put(SESSION, SESSION);
cache.put(SERVER, SERVER);
cache.put(DESTINATION, DESTINATION);
cache.put(ID, ID);
cache.put(ACK, ACK);
cache.put(TRANSACTION, TRANSACTION);
cache.put(RECEIPT, RECEIPT);
cache.put(MESSAGE_ID, MESSAGE_ID);
cache.put(SUBSCRIPTION, SUBSCRIPTION);
cache.put(RECEIPT_ID, RECEIPT_ID);
cache.put(MESSAGE, MESSAGE);
cache.put(CONTENT_LENGTH, CONTENT_LENGTH);
cache.put(CONTENT_TYPE, CONTENT_TYPE);
return cache;
}
};
@Override
protected void encode(ChannelHandlerContext ctx, StompSubframe msg, List<Object> out) throws Exception {
if (msg instanceof StompFrame) {
StompFrame stompFrame = (StompFrame) msg;
ByteBuf buf = encodeFullFrame(stompFrame, ctx);
out.add(convertFullFrame(stompFrame, buf));
} else if (msg instanceof StompHeadersSubframe) {
StompHeadersSubframe stompHeadersSubframe = (StompHeadersSubframe) msg;
ByteBuf buf = ctx.alloc().buffer(headersSubFrameSize(stompHeadersSubframe));
encodeHeaders(stompHeadersSubframe, buf);
out.add(convertHeadersSubFrame(stompHeadersSubframe, buf));
} else if (msg instanceof StompContentSubframe) {
StompContentSubframe stompContentSubframe = (StompContentSubframe) msg;
ByteBuf buf = encodeContent(stompContentSubframe, ctx);
out.add(convertContentSubFrame(stompContentSubframe, buf));
}
}
/**
* An extension method to convert a STOMP encoded buffer to a different message type
* based on an original {@link StompFrame} full frame.
*
* <p>By default an encoded buffer is returned as is.
*/
protected Object convertFullFrame(StompFrame original, ByteBuf encoded) {
return encoded;
}
/**
* An extension method to convert a STOMP encoded buffer to a different message type
* based on an original {@link StompHeadersSubframe} headers sub frame.
*
* <p>By default an encoded buffer is returned as is.
*/
protected Object convertHeadersSubFrame(StompHeadersSubframe original, ByteBuf encoded) {
return encoded;
}
/**
* An extension method to convert a STOMP encoded buffer to a different message type
* based on an original {@link StompHeadersSubframe} content sub frame.
*
* <p>By default an encoded buffer is returned as is.
*/
protected Object convertContentSubFrame(StompContentSubframe original, ByteBuf encoded) {
return encoded;
}
/**
* Returns a heuristic size for headers (32 bytes per header line) + (2 bytes for colon and eol) + (additional
* command buffer).
*/
protected int headersSubFrameSize(StompHeadersSubframe headersSubframe) {
int estimatedSize = headersSubframe.headers().size() * 34 + 48;
if (estimatedSize < 128) {
return 128;
}
return Math.max(estimatedSize, 256);
}
private ByteBuf encodeFullFrame(StompFrame frame, ChannelHandlerContext ctx) {
int contentReadableBytes = frame.content().readableBytes();
ByteBuf buf = ctx.alloc().buffer(headersSubFrameSize(frame) + contentReadableBytes);
encodeHeaders(frame, buf);
if (contentReadableBytes > 0) {
buf.writeBytes(frame.content());
}
return buf.writeByte(NUL);
}
private static void encodeHeaders(StompHeadersSubframe frame, ByteBuf buf) {
StompCommand command = frame.command();
ByteBufUtil.writeUtf8(buf, command.toString());
buf.writeByte(StompConstants.LF);
boolean shouldEscape = shouldEscape(command);
LinkedHashMap<CharSequence, CharSequence> cache = ESCAPE_HEADER_KEY_CACHE.get();
for (Entry<CharSequence, CharSequence> entry : frame.headers()) {
CharSequence headerKey = entry.getKey();
if (shouldEscape) {
CharSequence cachedHeaderKey = cache.get(headerKey);
if (cachedHeaderKey == null) {
cachedHeaderKey = escape(headerKey);
cache.put(headerKey, cachedHeaderKey);
}
headerKey = cachedHeaderKey;
}
ByteBufUtil.writeUtf8(buf, headerKey);
buf.writeByte(StompConstants.COLON);
CharSequence headerValue = shouldEscape? escape(entry.getValue()) : entry.getValue();
ByteBufUtil.writeUtf8(buf, headerValue);
buf.writeByte(StompConstants.LF);
}
buf.writeByte(StompConstants.LF);
}
private static ByteBuf encodeContent(StompContentSubframe content, ChannelHandlerContext ctx) {
if (content instanceof LastStompContentSubframe) {
ByteBuf buf = ctx.alloc().buffer(content.content().readableBytes() + 1);
buf.writeBytes(content.content());
buf.writeByte(StompConstants.NUL);
return buf;
}
return content.content().retain();
}
private static boolean shouldEscape(StompCommand command) {
return command != StompCommand.CONNECT && command != StompCommand.CONNECTED;
}
private static CharSequence escape(CharSequence input) {
AppendableCharSequence builder = null;
for (int i = 0; i < input.length(); i++) {
char chr = input.charAt(i);
if (chr == '\\') {
builder = escapeBuilder(builder, input, i);
builder.append("\\\\");
} else if (chr == ':') {
builder = escapeBuilder(builder, input, i);
builder.append("\\c");
} else if (chr == '\n') {
builder = escapeBuilder(builder, input, i);
builder.append("\\n");
} else if (chr == '\r') {
builder = escapeBuilder(builder, input, i);
builder.append("\\r");
} else if (builder != null) {
builder.append(chr);
}
}
return builder != null? builder : input;
}
private static AppendableCharSequence escapeBuilder(AppendableCharSequence builder, CharSequence input,
int offset) {
if (builder != null) {
return builder;
}
// Add extra overhead to the input char sequence to avoid resizing during escaping.
return new AppendableCharSequence(input.length() + 8).append(input, 0, offset);
}
}