/* * Copyright 2017 Anton Tananaev (anton@traccar.org) * * 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.traccar.protocol; import org.jboss.netty.buffer.ChannelBuffer; import org.jboss.netty.channel.Channel; import org.jboss.netty.channel.ChannelHandlerContext; import org.jboss.netty.handler.codec.frame.FrameDecoder; import java.nio.charset.StandardCharsets; import java.util.Arrays; import java.util.HashSet; import java.util.Set; public class Gl200FrameDecoder extends FrameDecoder { private static final int MINIMUM_LENGTH = 11; private static final Set<String> BINARY_HEADERS = new HashSet<>( Arrays.asList("+RSP", "+BSP", "+EVT", "+BVT", "+INF", "+BNF", "+HBD", "+CRD", "+BRD")); public static boolean isBinary(ChannelBuffer buf) { String header = buf.toString(buf.readerIndex(), 4, StandardCharsets.US_ASCII); if (header.equals("+ACK")) { return buf.getByte(buf.readerIndex() + header.length()) != (byte) ':'; } else { return BINARY_HEADERS.contains(header); } } @Override protected Object decode( ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception { if (buf.readableBytes() < MINIMUM_LENGTH) { return null; } if (isBinary(buf)) { int length; switch (buf.toString(buf.readerIndex(), 4, StandardCharsets.US_ASCII)) { case "+ACK": length = buf.getUnsignedByte(buf.readerIndex() + 6); break; case "+INF": case "+BNF": length = buf.getUnsignedShort(buf.readerIndex() + 7); break; case "+HBD": length = buf.getUnsignedByte(buf.readerIndex() + 5); break; case "+CRD": case "+BRD": length = buf.getUnsignedShort(buf.readerIndex() + 6); break; default: length = buf.getUnsignedShort(buf.readerIndex() + 9); break; } if (buf.readableBytes() >= length) { return buf.readBytes(length); } } else { int endIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '$'); if (endIndex < 0) { endIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) 0); } if (endIndex > 0) { ChannelBuffer frame = buf.readBytes(endIndex - buf.readerIndex()); buf.readByte(); // delimiter return frame; } } return null; } }