com.mpush.api.protocol.Packet.java Source code

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Here is the source code for com.mpush.api.protocol.Packet.java

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/*
 * (C) Copyright 2015-2016 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.
 *
 * Contributors:
 *   ohun@live.cn ()
 */

package com.mpush.api.protocol;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;

import java.net.InetSocketAddress;

/**
 * Created by ohun on 2015/12/19.
 * length(4)+cmd(1)+cc(2)+flags(1)+sessionId(4)+lrc(1)+body(n)
 *
 * @author ohun@live.cn
 */
@SuppressWarnings("unchecked")
public class Packet {
    public static final int HEADER_LEN = 13;

    public static final byte FLAG_CRYPTO = 1;
    public static final byte FLAG_COMPRESS = 2;
    public static final byte FLAG_BIZ_ACK = 4;
    public static final byte FLAG_AUTO_ACK = 8;
    public static final byte FLAG_JSON_BODY = 16;

    public static final byte HB_PACKET_BYTE = -33;
    public static final byte[] HB_PACKET_BYTES = new byte[] { HB_PACKET_BYTE };
    public static final Packet HB_PACKET = new Packet(Command.HEARTBEAT);

    public byte cmd; //
    transient public short cc; //? 
    public byte flags; //??
    public int sessionId; // ?id?
    transient public byte lrc; // ??head
    transient public byte[] body;

    public Packet(byte cmd) {
        this.cmd = cmd;
    }

    public Packet(byte cmd, int sessionId) {
        this.cmd = cmd;
        this.sessionId = sessionId;
    }

    public Packet(Command cmd) {
        this.cmd = cmd.cmd;
    }

    public Packet(Command cmd, int sessionId) {
        this.cmd = cmd.cmd;
        this.sessionId = sessionId;
    }

    public int getBodyLength() {
        return body == null ? 0 : body.length;
    }

    public void addFlag(byte flag) {
        this.flags |= flag;
    }

    public boolean hasFlag(byte flag) {
        return (flags & flag) != 0;
    }

    public <T> T getBody() {
        return (T) body;
    }

    public <T> void setBody(T body) {
        this.body = (byte[]) body;
    }

    public short calcCheckCode() {
        short checkCode = 0;
        if (body != null) {
            for (int i = 0; i < body.length; i++) {
                checkCode += (body[i] & 0x0ff);
            }
        }
        return checkCode;
    }

    public byte calcLrc() {
        byte[] data = Unpooled.buffer(HEADER_LEN - 1).writeInt(getBodyLength()).writeByte(cmd).writeShort(cc)
                .writeByte(flags).writeInt(sessionId).array();
        byte lrc = 0;
        for (int i = 0; i < data.length; i++) {
            lrc ^= data[i];
        }
        return lrc;
    }

    public boolean validCheckCode() {
        return calcCheckCode() == cc;
    }

    public boolean validLrc() {
        return (lrc ^ calcLrc()) == 0;
    }

    public InetSocketAddress sender() {
        return null;
    }

    public void setRecipient(InetSocketAddress sender) {
    }

    public Packet response(Command command) {
        return new Packet(command, sessionId);
    }

    public Object toFrame(Channel channel) {
        return this;
    }

    public static Packet decodePacket(Packet packet, ByteBuf in, int bodyLength) {
        packet.cc = in.readShort();//read cc
        packet.flags = in.readByte();//read flags
        packet.sessionId = in.readInt();//read sessionId
        packet.lrc = in.readByte();//read lrc

        //read body
        if (bodyLength > 0) {
            in.readBytes(packet.body = new byte[bodyLength]);
        }
        return packet;
    }

    public static void encodePacket(Packet packet, ByteBuf out) {
        if (packet.cmd == Command.HEARTBEAT.cmd) {
            out.writeByte(Packet.HB_PACKET_BYTE);
        } else {
            out.writeInt(packet.getBodyLength());
            out.writeByte(packet.cmd);
            out.writeShort(packet.cc);
            out.writeByte(packet.flags);
            out.writeInt(packet.sessionId);
            out.writeByte(packet.lrc);
            if (packet.getBodyLength() > 0) {
                out.writeBytes(packet.body);
            }
        }
        packet.body = null;
    }

    @Override
    public String toString() {
        return "{" + "cmd=" + cmd + ", cc=" + cc + ", flags=" + flags + ", sessionId=" + sessionId + ", lrc=" + lrc
                + ", body=" + (body == null ? 0 : body.length) + '}';
    }

    public static ByteBuf getHBPacket() {
        return Unpooled.wrappedBuffer(HB_PACKET_BYTES);
    }
}