116 lines
4.1 KiB
Java
116 lines
4.1 KiB
Java
package i2p.bote.packet;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.TimeUnit;
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import net.i2p.util.Log;
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public abstract class CommunicationPacket extends I2PBotePacket {
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private static final byte PACKET_VERSION = 1;
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protected static final int HEADER_LENGTH = 6 + UniqueId.LENGTH; // length of the common packet header in the byte array representation; this is where subclasses start reading
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private static final byte[] PACKET_PREFIX = new byte[] {(byte)0x6D, (byte)0x30, (byte)0x52, (byte)0xE9};
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private static Log static_log = new Log(CommunicationPacket.class);
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private Log log = new Log(CommunicationPacket.class);
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private UniqueId packetId;
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private CountDownLatch sentSignal;
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private long sentTime;
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protected CommunicationPacket() {
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this(new UniqueId());
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}
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protected CommunicationPacket(UniqueId packetId) {
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this.packetId = packetId;
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sentSignal = new CountDownLatch(1);
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sentTime = -1;
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}
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/**
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* Creates a packet and initializes the header fields shared by all Communication Packets: packet type and packet id.
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* @param data
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*/
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protected CommunicationPacket(byte[] data) {
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verifyHeader(data);
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checkPacketType(data[4]);
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packetId = new UniqueId(data, 6);
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}
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/**
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* Creates a packet object from its byte array representation. If there is an error,
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* <code>null</code> is returned.
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* @param data
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* @param log
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* @return
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*/
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public static CommunicationPacket createPacket(byte[] data) {
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char packetTypeCode = (char)data[4]; // byte 4 of a communication packet is the packet type code
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Class<? extends I2PBotePacket> packetType = decodePacketTypeCode(packetTypeCode);
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if (packetType==null || !CommunicationPacket.class.isAssignableFrom(packetType)) {
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static_log.error("Type code is not a CommunicationPacket type code: <" + packetTypeCode + ">");
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return null;
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}
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Class<? extends CommunicationPacket> commPacketType = packetType.asSubclass(CommunicationPacket.class);
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try {
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return commPacketType.getConstructor(byte[].class).newInstance(data);
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}
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catch (Exception e) {
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static_log.warn("Can't instantiate packet for type code <" + packetTypeCode + ">", e);
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return null;
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}
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}
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// check the packet prefix and version number of a packet
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private void verifyHeader(byte[] packet) {
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for (int i=0; i<PACKET_PREFIX.length; i++)
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if (packet[i] != PACKET_PREFIX[i])
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log.error("Packet prefix invalid at byte " + i + ". Expected = " + PACKET_PREFIX[i] + ", actual = " + packet[i]);
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if (packet[5] != 1)
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log.error("Unsupported packet version: " + packet[5]);
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}
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public void setPacketId(UniqueId packetId) {
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this.packetId = packetId;
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}
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public UniqueId getPacketId() {
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return packetId;
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}
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public synchronized void setSentTime(long sentTime) {
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this.sentTime = sentTime;
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sentSignal.countDown();
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}
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public synchronized long getSentTime() {
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return sentTime;
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}
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public boolean hasBeenSent() {
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return sentTime > 0;
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}
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public boolean awaitSending(long timeout, TimeUnit unit) throws InterruptedException {
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return sentSignal.await(timeout, unit);
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}
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/**
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* Writes the Prefix, Version, Type, and Packet Id fields of a I2PBote packet to
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* an {@link OutputStream}.
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* @param outputStream
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*/
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protected void writeHeader(OutputStream outputStream) throws IOException {
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outputStream.write(PACKET_PREFIX);
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outputStream.write((byte)getPacketTypeCode());
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outputStream.write(PACKET_VERSION);
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outputStream.write(packetId.toByteArray());
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}
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@Override
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public String toString() {
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return "Type=" + getClass().getSimpleName() + " Id=" + (packetId==null?"<null>":packetId.toString().substring(0, 8)) + "...";
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}
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} |