/*
* Copyright 2010 NCHOVY
*
* 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.krakenapps.pcap.decoder.tcp;
import org.krakenapps.pcap.util.Buffer;
public class TcpSackReassembler {
private TcpSackReassembler() {
}
public static void insert(TcpSessionImpl session, TcpPacket packet) {
WaitQueue queue;
if (packet.getDirection() == TcpDirection.ToServer)
queue = session.getServerQueue();
else
queue = session.getClientQueue();
queue.enqueue(packet);
}
/* return: reassembled packet */
public static TcpPacket reassemble(TcpSessionImpl session, TcpPacket packet, TcpStateUpdater stateUpdater) {
TcpHost host;
WaitQueue queue;
if (packet.getDirection() == TcpDirection.ToServer) {
host = session.getServer();
queue = session.getServerQueue();
} else {
host = session.getClient();
queue = session.getClientQueue();
}
return doReassemble(queue, session, host, packet);
}
private static TcpPacket doReassemble(WaitQueue queue, TcpSessionImpl session, TcpHost host, TcpPacket packet) {
TcpPacket p;
while (true) {
p = findNextDatagram(queue, host.getLastFrameReceived());
if (p == null) {
return null;
}
if (p.getData() != null) {
Buffer data = p.getData();
int readable = data.readableBytes();
if(p.getDataLength() < readable) {
p.setReassembledLength(p.getDataLength());
data.skip(p.getDataLength());
data.flip();
}
else
p.setReassembledLength(readable);
if (packet.getDirection() == TcpDirection.ToServer)
session.pushToClientSack(data);
else
session.pushToServerSack(data);
}
return p;
}
}
private static TcpPacket findNextDatagram(WaitQueue queue, int lastReceived) {
for (int i = 0; i < queue.size(); i++) {
TcpPacket p = queue.dequeue(i);
int seq = p.getRelativeSeq();
if (seq == lastReceived) {
queue.remove(i);
return p;
} else if (seq + p.getDataLength() > lastReceived) {
if (seq > lastReceived || p.getData() == null)
continue;
/* check TCP packet range. drop received data(=garbage) */
int garbage = lastReceived - seq;
Buffer tcpData = p.getData();
tcpData.skip(garbage);
tcpData.discardReadBytes();
queue.remove(i);
return p;
}
}
return null;
}
}