Program: 96695
Project: 96695
Buggy source:
private void processPacketBuffer(byte[] buffer){
  PEPacket packet=Protocol.decode(buffer);
  if (packet == null) {
    return;
  }
switch (packet.pid()) {
case PEPacketIDs.PING:
    PingPongPacket pkPong=new PingPongPacket();
  pkPong.pingID=((PingPongPacket)packet).pingID;
this.send(pkPong,0);
break;
case PEPacketIDs.CLIENT_CONNECT:
if (this.loginStage != 0) {
break;
}
this.clientSessionID=((ClientConnectPacket)packet).sessionID;
ServerHandshakePacket pkServerHandshake=new ServerHandshakePacket();
pkServerHandshake.addr=this.getAddress().getAddress();
pkServerHandshake.port=(short)(0 & 0xFFFF);
pkServerHandshake.session=this.clientSessionID;
pkServerHandshake.session2=this.clientSessionID + 1000L;
this.loginStage=1;
this.send(pkServerHandshake);
break;
case PEPacketIDs.CLIENT_HANDSHAKE:
if (this.loginStage != 1) {
break;
}
this.loginStage=2;
break;
case PEPacketIDs.LOGIN_PACKET:
if (this.loginStage != 2) {
break;
}
LoginPacket packetLogin=(LoginPacket)packet;
this.username=packetLogin.username;
this.translator=TranslatorProvider.getByPEProtocolID(this,packetLogin.protocol1);
if (!(this.translator instanceof BaseTranslator)) {
LoginStatusPacket pkLoginStatus=new LoginStatusPacket();
pkLoginStatus.status=LoginStatusPacket.LOGIN_FAILED_CLIENT;
this.send(pkLoginStatus);
this.disconnect("String_Node_Str");
break;
}
LoginStatusPacket pkLoginStatus=new LoginStatusPacket();
pkLoginStatus.status=0;
this.send(pkLoginStatus);
this.getLogger().info("String_Node_Str" + this.username + "String_Node_Str");
Matcher matcher=patternUsername.matcher(this.username);
if (!matcher.matches()) {
this.disconnect("String_Node_Str");
break;
}
this.loginStage=3;
this.setPlayer(new PlayerProfile(this.username,UUID.nameUUIDFromBytes(("String_Node_Str" + this.username).getBytes(StandardCharsets.UTF_8))));
break;
case PEPacketIDs.DISCONNECT_PACKET:
this.onDisconnect();
break;
default :
if (this.loginStage != 3) {
break;
}
if (!(this.translator instanceof BaseTranslator)) {
break;
}
this.dServer.getThreadPool().submit(new ProcessPEPacketTask(this,packet));
break;
}
}

Fixed version (ground truth):
private void processPacketBuffer(byte[] buffer){
  PEPacket packet=Protocol.decode(buffer);
  if (packet == null) {
    return;
  }
switch (packet.pid()) {
case PEPacketIDs.PING:
    PingPongPacket pkPong=new PingPongPacket();
  pkPong.pingID=((PingPongPacket)packet).pingID;
this.send(pkPong,0);
break;
case PEPacketIDs.CLIENT_CONNECT:
if (this.loginStage != 0) {
break;
}
this.clientSessionID=((ClientConnectPacket)packet).sessionID;
ServerHandshakePacket pkServerHandshake=new ServerHandshakePacket();
pkServerHandshake.addr=this.getAddress().getAddress();
pkServerHandshake.port=(short)(0 & 0xFFFF);
pkServerHandshake.session=this.clientSessionID;
pkServerHandshake.session2=this.clientSessionID + 1000L;
this.loginStage=1;
this.send(pkServerHandshake);
break;
case PEPacketIDs.CLIENT_HANDSHAKE:
if (this.loginStage != 1) {
break;
}
this.loginStage=2;
break;
case PEPacketIDs.LOGIN_PACKET:
if (this.loginStage != 2) {
break;
}
LoginPacket packetLogin=(LoginPacket)packet;
this.username=packetLogin.username;
this.translator=TranslatorProvider.getByPEProtocolID(this,packetLogin.protocol1);
if (!(this.translator instanceof BaseTranslator)) {
LoginStatusPacket pkLoginStatus=new LoginStatusPacket();
pkLoginStatus.status=LoginStatusPacket.LOGIN_FAILED_CLIENT;
this.send(pkLoginStatus);
this.disconnect("String_Node_Str");
break;
}
LoginStatusPacket pkLoginStatus=new LoginStatusPacket();
pkLoginStatus.status=0;
this.send(pkLoginStatus);
this.getLogger().info("String_Node_Str" + this.username + "String_Node_Str");
Matcher matcher=patternUsername.matcher(this.username);
if (!matcher.matches()) {
this.disconnect("String_Node_Str");
break;
}
this.loginStage=3;
this.setPlayer(new PlayerProfile(this.username,UUID.nameUUIDFromBytes(("String_Node_Str" + this.username).getBytes(StandardCharsets.UTF_8))));
break;
case PEPacketIDs.DISCONNECT_PACKET:
this.onDisconnect();
break;
case PEPacketIDs.BATCH_PACKET:
BatchPacket packetBatch=(BatchPacket)packet;
if (packetBatch.packets == null || packetBatch.packets.isEmpty()) {
return;
}
for (PEPacket pk : packetBatch.packets) {
if (pk.pid() == PEPacketIDs.LOGIN_PACKET) {
if (this.loginStage != 2) {
break;
}
LoginPacket packetLogin1=(LoginPacket)pk;
this.username=packetLogin1.username;
this.translator=TranslatorProvider.getByPEProtocolID(this,packetLogin1.protocol1);
if (!(this.translator instanceof BaseTranslator)) {
LoginStatusPacket pkLoginStatus1=new LoginStatusPacket();
pkLoginStatus1.status=LoginStatusPacket.LOGIN_FAILED_CLIENT;
this.send(pkLoginStatus1);
this.disconnect("String_Node_Str");
break;
}
LoginStatusPacket pkLoginStatus1=new LoginStatusPacket();
pkLoginStatus1.status=0;
this.send(pkLoginStatus1);
this.getLogger().info("String_Node_Str" + this.username + "String_Node_Str");
Matcher matcher1=patternUsername.matcher(this.username);
if (!matcher1.matches()) {
this.disconnect("String_Node_Str");
break;
}
this.loginStage=3;
this.setPlayer(new PlayerProfile(this.username,UUID.nameUUIDFromBytes(("String_Node_Str" + this.username).getBytes(StandardCharsets.UTF_8))));
continue;
}
if (!(this.translator instanceof BaseTranslator)) {
break;
}
this.dServer.getThreadPool().submit(new ProcessPEPacketTask(this,pk));
}
break;
default :
if (this.loginStage != 3) {
break;
}
if (!(this.translator instanceof BaseTranslator)) {
break;
}
this.dServer.getThreadPool().submit(new ProcessPEPacketTask(this,packet));
break;
}
}