13
0
geforkt von Mirrors/Velocity

Try two, with improved state maintenance and some bugs fixed

Dieser Commit ist enthalten in:
Andrew Steinborn 2020-05-31 08:14:33 -04:00
Ursprung 3a8ba76f25
Commit c856635ac5

Datei anzeigen

@ -1,15 +1,17 @@
package com.velocitypowered.proxy.protocol.netty;
import com.velocitypowered.proxy.protocol.ProtocolUtils;
import com.velocitypowered.proxy.util.except.QuietException;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.util.ByteProcessor;
import java.util.List;
public class MinecraftVarintFrameDecoder extends ByteToMessageDecoder {
private static final QuietException BAD_LENGTH_CACHED = new QuietException("Bad packet length");
private static final QuietException VARINT_BIG_CACHED = new QuietException("VarInt too big");
private final VarintByteDecoder reader = new VarintByteDecoder();
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
@ -18,31 +20,65 @@ public class MinecraftVarintFrameDecoder extends ByteToMessageDecoder {
return;
}
read_lens: while (in.isReadable()) {
int origReaderIndex = in.readerIndex();
for (int i = 0; i < 3; i++) {
if (!in.isReadable()) {
in.readerIndex(origReaderIndex);
return;
}
while (in.isReadable()) {
reader.reset();
byte read = in.readByte();
if (read >= 0) {
// Make sure reader index of length buffer is returned to the beginning
in.readerIndex(origReaderIndex);
int packetLength = ProtocolUtils.readVarInt(in);
if (in.readableBytes() >= packetLength) {
out.add(in.readBytes(packetLength));
continue read_lens;
} else {
in.readerIndex(origReaderIndex);
return;
}
}
int varintEnd = in.forEachByte(reader);
if (varintEnd == -1) {
// We tried to go beyond the end of the buffer. This is probably a good sign that the
// buffer was too short to hold a proper varint.
return;
}
throw BAD_LENGTH_CACHED;
if (reader.result == DecodeResult.SUCCESS) {
if (reader.readVarint < 0) {
throw BAD_LENGTH_CACHED;
}
int minimumRead = reader.bytesRead + reader.readVarint;
if (in.isReadable(minimumRead)) {
out.add(in.retainedSlice(varintEnd + 1, reader.readVarint));
in.skipBytes(minimumRead);
} else {
return;
}
} else if (reader.result == DecodeResult.TOO_BIG) {
throw VARINT_BIG_CACHED;
} else if (reader.result == DecodeResult.TOO_SHORT) {
// No-op: we couldn't get a useful result.
}
}
}
private static class VarintByteDecoder implements ByteProcessor {
private int readVarint;
private int bytesRead;
private DecodeResult result = DecodeResult.TOO_SHORT;
@Override
public boolean process(byte k) {
readVarint |= (k & 0x7F) << bytesRead++ * 7;
if (bytesRead > 3) {
result = DecodeResult.TOO_BIG;
return false;
}
if ((k & 0x80) != 128) {
result = DecodeResult.SUCCESS;
return false;
}
return true;
}
void reset() {
readVarint = 0;
bytesRead = 0;
result = DecodeResult.TOO_SHORT;
}
}
private enum DecodeResult {
SUCCESS,
TOO_SHORT,
TOO_BIG
}
}