MaimMim Man in the middle minetest interceptor

- prototype
- between client and server, allow to capture all exchanges and potentially change them
- created to capture server maps in laby
- first test get only MapBlock, support version serialization version 28
  - prepartion for 29 with zstd but untested.

java/org/artisanlogiciel/games/minetest/net/Address.java

@@ -0,0 +1,4 @@
+package org.artisanlogiciel.games.minetest.net;
+
+public class Address {
+}

java/org/artisanlogiciel/games/minetest/net/BufferedPacket.java

@@ -0,0 +1,28 @@
+package org.artisanlogiciel.games.minetest.net;
+
+import org.artisanlogiciel.games.minetest.core.PacketException;
+import org.artisanlogiciel.games.minetest.core.Serialize;
+
+public class BufferedPacket {
+
+    public static int BASE_HEADER_SIZE = 7;
+
+    // Data of the packet, including headers
+    byte[] m_data;
+
+    BufferedPacket(byte[] data)
+    {
+        m_data = data;
+    }
+
+    int getSeqNum()
+            throws PacketException
+    {
+        return Serialize.readU16(m_data, BASE_HEADER_SIZE + 1, size());
+    }
+
+    int size()
+    {
+        return m_data.length;
+    }
+}

java/org/artisanlogiciel/games/minetest/net/Channel.java

@@ -0,0 +1,9 @@
+package org.artisanlogiciel.games.minetest.net;
+
+public class Channel {
+
+    int readNextIncomingSeqNum()
+    {
+        return 0;
+    }
+}

java/org/artisanlogiciel/games/minetest/net/ConnectionEvent.java

@@ -0,0 +1,45 @@
+package org.artisanlogiciel.games.minetest.net;
+
+public class ConnectionEvent {
+
+    ConnectionEventType m_event_type;
+    int m_peer_id;
+    byte[] m_data;
+    boolean m_timeout;
+
+
+    ConnectionEvent(ConnectionEventType eventType)
+    {
+        m_event_type = eventType;
+    }
+
+    String describe()
+    {
+        return m_event_type.toString();
+    }
+
+    ConnectionEventPtr create(ConnectionEventType type)
+    {
+        return null;
+    }
+
+	ConnectionEventPtr dataReceived(int peer_id, byte[] data)
+    {
+        return null;
+    }
+
+    ConnectionEventPtr peerAdded(int peer_id, Address address)
+    {
+        return null;
+    }
+
+    ConnectionEventPtr peerRemoved(int peer_id, boolean is_timeout, Address address)
+    {
+        return null;
+    }
+
+	ConnectionEventPtr bindFailed()
+    {
+        return null;
+    }
+}

java/org/artisanlogiciel/games/minetest/net/ConnectionEventPtr.java

@@ -0,0 +1,4 @@
+package org.artisanlogiciel.games.minetest.net;
+
+public class ConnectionEventPtr {
+}

java/org/artisanlogiciel/games/minetest/net/ConnectionEventType.java

@@ -0,0 +1,9 @@
+package org.artisanlogiciel.games.minetest.net;
+
+public enum ConnectionEventType {
+    CONNEVENT_NONE,
+	CONNEVENT_DATA_RECEIVED,
+	CONNEVENT_PEER_ADDED,
+	CONNEVENT_PEER_REMOVED,
+	CONNEVENT_BIND_FAILED
+}

java/org/artisanlogiciel/games/minetest/net/IncomingSplitBuffer.java

@@ -0,0 +1,90 @@
+package org.artisanlogiciel.games.minetest.net;
+
+import org.artisanlogiciel.games.minetest.core.PacketException;
+import org.artisanlogiciel.games.minetest.core.Serialize;
+
+import java.util.ArrayList;
+
+public class IncomingSplitBuffer {
+
+    int m_seqnum;
+    int m_chunk_count;
+    int m_chunk_num;
+
+    // number of chunks
+    int m_got = 0;
+
+    NetworkPacket m_list[] = null;
+    BufferedPacket m_reassembled = null;
+
+    BufferedPacket insert(NetworkPacket networkPacket)
+            throws PacketException
+    {
+
+        byte[] buffer = networkPacket.getBuffer();
+        int length = networkPacket.getLength();
+        int offset = networkPacket.getOffset();
+
+        int type = Serialize.readU8(buffer , offset, length);
+        int seqnum = Serialize.readU16(buffer, offset + 1, length);
+        // total number of chunk
+        int chunk_count = Serialize.readU16(buffer, offset + 3, length);
+        // this chunk number
+        int chunk_num = Serialize.readU16(buffer, offset+ 5, length);
+
+        System.out.println("Split length " + length + " type " + type + " seqnum " + seqnum + " chunk_num/chunk_count " + chunk_num + "/" + chunk_count );
+
+        // move to next header
+        networkPacket.addOffset(7);
+
+        if (m_reassembled != null)
+        {
+            return m_reassembled;
+        }
+
+        if (m_list == null )
+        {
+            m_list = new NetworkPacket[chunk_count];
+        }
+
+        if ( chunk_num < chunk_count && (m_list[chunk_num] == null) )
+        {
+            m_list[chunk_num] = networkPacket;
+            m_got ++;
+        }
+        //todo seqnum
+        m_seqnum = seqnum;
+
+        // fully obtained
+        if ( m_got == chunk_count )
+        {
+            reassemble();
+        }
+
+        return m_reassembled;
+
+    }
+
+    private void reassemble()
+    {
+        // keep first header since result is a valid BufferedPacket
+        int fullLength = BufferedPacket.BASE_HEADER_SIZE;
+        for (NetworkPacket networkPacket : m_list )
+        {
+            fullLength += networkPacket.getLength() - networkPacket.getOffset();
+        }
+        byte[] reassembled = new byte[fullLength];
+        NetworkPacket first = m_list[0];
+        System.arraycopy(first.getBuffer(),0,reassembled,0,BufferedPacket.BASE_HEADER_SIZE);
+        int offset = BufferedPacket.BASE_HEADER_SIZE;
+        for (NetworkPacket networkPacket : m_list )
+        {
+            int dataLength = networkPacket.getLength() - networkPacket.getOffset();
+            System.arraycopy(networkPacket.getBuffer(), networkPacket.getOffset(),reassembled,offset,dataLength);
+            offset+=dataLength;
+        }
+        m_reassembled = new BufferedPacket(reassembled);
+
+    }
+
+}

java/org/artisanlogiciel/games/minetest/net/MiM.java

@@ -0,0 +1,127 @@
+package org.artisanlogiciel.games.minetest.net;
+
+import org.artisanlogiciel.games.minetest.core.PacketException;
+
+import java.io.IOException;
+import java.net.*;
+
+/**
+ * Man in the middle UDP
+ * very simple for one client only
+ */
+
+public class MiM {
+
+    DatagramSocket serverSocket;
+    boolean running = false;
+    InetSocketAddress serverAddress;
+    // will be captured, incoming address & port
+    SocketAddress fromClient = null;
+    int localPort;
+    PacketHandler handler = null;
+
+    public MiM(int myPort, InetSocketAddress remoteAddress)
+    {
+        localPort = myPort;
+        serverAddress = remoteAddress;
+    }
+
+    public void launch()
+    {
+        // ServerSocket socket = new ServerSocket()
+        try {
+            handler = new PacketHandler();
+            serverSocket = new DatagramSocket(localPort);
+            DatagramSocket in = serverSocket;
+            SocketAddress fromServer = serverAddress;
+            Thread toServer = new Thread( () -> {runFromToServer(in,fromServer);});
+            running = true;
+            toServer.start();
+        }
+        catch(Exception e)
+        {
+            System.out.println("problem");
+            e.printStackTrace(System.err);
+            running = false;
+        }
+    }
+
+    public void stop()
+    {
+        running = false;
+    }
+
+    public void runFromToServer(DatagramSocket in, SocketAddress fromServer) {
+        try {
+
+            while (running) {
+                // quick way, a new buffer at each reception
+                // to handle split packets that are buffered
+                byte[] buf = new byte[4096];
+                SocketAddress toRemote = null;
+                DatagramPacket packet = new DatagramPacket(buf, buf.length);
+                in.receive(packet);
+                SocketAddress from = packet.getSocketAddress();
+                if ( from.equals(fromServer)) {
+                    // no client yet
+                    if ( fromClient == null )
+                    {
+                        continue;
+                    }
+                    fromServer(buf,packet.getLength());
+                    toRemote = fromClient;
+                }
+                else
+                {
+                    // record client
+                    // later on to be smart : could try to record peer id ?
+                    // will add a constraint : only one auth at a time
+                    if ( fromClient == null ) {
+                        fromClient = from;
+                    }
+                    fromClient(buf,packet.getLength());
+                    toRemote = fromServer;
+                }
+                packet = new DatagramPacket(buf, packet.getLength(), toRemote);
+                in.send(packet);
+            }
+        }
+        catch( IOException ioException)
+        {
+            //
+            System.out.println("oops");
+        }
+        // socket.close();
+    }
+
+    void fromServer(byte[] buffer, int length)
+    {
+        try {
+            // reply from server
+            if (handler != null) {
+                handler.fromServer(buffer, length);
+            }
+        }
+        catch (PacketException packetException)
+        {
+            //
+        }
+    }
+
+    void fromClient(byte[] buffer, int length)
+    {
+        try {
+            // reply from client
+            if (handler != null) {
+                handler.fromClient(buffer, length);
+            }
+        }
+        catch (PacketException packetException)
+        {
+            //
+        }
+
+    }
+
+
+}

java/org/artisanlogiciel/games/minetest/net/NetworkPacket.java

@@ -0,0 +1,70 @@
+package org.artisanlogiciel.games.minetest.net;
+
+import org.artisanlogiciel.games.minetest.core.PacketException;
+import org.artisanlogiciel.games.minetest.core.Serialize;
+import org.artisanlogiciel.games.minetest.core.v3s16;
+
+import java.nio.ByteBuffer;
+
+public class NetworkPacket {
+
+    int m_protocol_id;
+    int m_peer_id;
+    int m_channel;
+    public PacketType packetType;
+
+    // somehow a BufferedPacket ...
+    byte[] m_buffer; // m_data
+    // used part in buffer
+    int m_length; // m_datasize ?
+    // current header index in packet
+    int m_offset; // m_read_offset
+
+    short m_command = 0;
+
+    public NetworkPacket(int protocol_id, int peer_id, int channel, PacketType type, byte[] buffer, int length) {
+        this.m_protocol_id = protocol_id;
+        this.m_peer_id = peer_id;
+        this.m_channel = channel;
+        this.packetType = type;
+        m_buffer = buffer;
+        m_length = length;
+        m_offset = 0;
+    }
+
+    public int getChannel()
+    {
+        return m_channel;
+    }
+
+    public byte[] getBuffer()
+    {
+        return m_buffer;
+    }
+
+    public int getOffset() {
+        return m_offset;
+    }
+
+    public int getLength() {
+        return m_length;
+    }
+
+    void addOffset(int offset)
+    {
+        m_offset += offset;
+    }
+
+    // Serialization
+    public v3s16 v3s16()
+            throws PacketException
+    {
+        return Serialize.readV3S16(m_buffer, m_offset, m_length);
+    }
+
+    public ByteBuffer getByteBuffer()
+    {
+        ByteBuffer buffer = ByteBuffer.wrap(m_buffer,m_offset,m_length-m_offset);
+        return buffer;
+    }
+}

java/org/artisanlogiciel/games/minetest/net/PacketHandler.java

@@ -0,0 +1,287 @@
+package org.artisanlogiciel.games.minetest.net;
+import com.github.luben.zstd.Zstd;
+import org.artisanlogiciel.games.minetest.MapBlock;
+import org.artisanlogiciel.games.minetest.MapNode;
+import org.artisanlogiciel.games.minetest.core.PacketException;
+import org.artisanlogiciel.games.minetest.core.Serialize;
+import org.artisanlogiciel.games.minetest.core.v2s16;
+import org.artisanlogiciel.games.minetest.core.v3s16;
+
+import java.nio.ByteBuffer;
+
+/**
+ * see src/network/networkprotocol.h of minetest sources
+ *
+ *
+ * === NOTES ===
+ *
+ * A packet is sent through a channel to a peer with a basic header:
+ * 	Header (7 bytes):
+ * 	[0] u32 protocol_id
+ * 	[4] session_t sender_peer_id
+ * 	[6] u8 channel
+ * sender_peer_id:
+ * 	Unique to each peer.
+ * 	value 0 (PEER_ID_INEXISTENT) is reserved for making new connections
+ * 	value 1 (PEER_ID_SERVER) is reserved for server
+ * 	these constants are defined in constants.h
+ * channel:
+ * 	Channel numbers have no intrinsic meaning. Currently only 0, 1, 2 exist.
+ *
+ *
+ * */
+
+public class PacketHandler {
+
+    ReliablePacketBuffer reliableBuffer = null;
+
+    IncomingSplitBuffer[] incomingChanneleSplitBuffer = new IncomingSplitBuffer[4];
+
+    // server serialization in hello version
+    int ser_version;
+
+    // minetest protocol should be 0x4f457403
+    static int readProtocolId(byte[] buffer, int length)
+            throws PacketException
+     {
+        return Serialize.readU32(buffer, 0, length);
+     }
+
+    static int readPeerId(byte[] buffer, int length)
+            throws PacketException
+    {
+        return Serialize.readU16(buffer,4,length);
+    }
+
+    static int readChannel(byte[] buffer, int length)
+            throws PacketException
+    {
+        return Serialize.readU8(buffer, 6, length);
+    }
+
+    NetworkPacket handleAny(byte[] buffer, int length)
+            throws PacketException
+    {
+        int protocol_id = readProtocolId(buffer, length);
+        int peer_id = readPeerId(buffer, length);
+        int channel = readChannel(buffer, length);
+        int type = Serialize.readU8(buffer,7,length);
+        PacketType packetType = PacketType.getPacketType(type);
+
+        NetworkPacket networkPacket = new NetworkPacket(protocol_id,peer_id,channel,packetType, buffer, length);
+
+        // offset of packet within buffer.
+        networkPacket.addOffset(BufferedPacket.BASE_HEADER_SIZE);
+
+        System.out.println("length " + length + " protocol_id " + String.format("%x", protocol_id) + " peer_id " + peer_id + " channel " + channel + " type " + packetType);
+
+        return networkPacket;
+    }
+
+    void handlePacketType_Control(NetworkPacket networkPacket)
+            throws PacketException {
+    }
+
+    void handlePacketType_Reliable(NetworkPacket networkPacket)
+            throws PacketException
+    {
+        // TODO handle misordered...
+        /*
+        if ( reliableBuffer == null )
+        {
+            reliableBuffer = new ReliablePacketBuffer();
+        }
+
+        BufferedPacket packet = new BufferedPacket(buffer);
+        int nextExpected = 0;
+        reliableBuffer.insert(packet, nextExpected);
+        */
+
+        // handle nested packet
+        networkPacket.addOffset(3);
+        int offset = networkPacket.getOffset();
+        byte buffer[] = networkPacket.getBuffer();
+        int length = networkPacket.getLength();
+
+        PacketType packetType = PacketType.getPacketType(Serialize.readU8(buffer,offset,length));
+
+        System.out.println( "reliable " + packetType.toString());
+
+        switch (packetType)
+        {
+            case PACKET_TYPE_CONTROL:
+                //
+                handlePacketType_Control(networkPacket);
+                break;
+            case PACKET_TYPE_ORIGINAL:
+                handlePacketType_Original(networkPacket);
+                break;
+            case PACKET_TYPE_SPLIT:
+                handlePacketType_Split(networkPacket);
+                break;
+            case PACKET_TYPE_RELIABLE:
+                // this is an error, no nested reliable accepted.
+                throw new PacketException("nested reliable");
+            default: // error
+                throw new PacketException("unknown type");
+        }
+
+    }
+
+    void handleCommand_Hello(NetworkPacket networkPacket)
+            throws PacketException {
+
+        // u8 deployed serialisation version
+        ByteBuffer buffer = networkPacket.getByteBuffer();
+        int ser_ver = Serialize.readU8(buffer);
+        ser_version = ser_ver;
+        // u16 deployed network compression mode
+        int net_compress = Serialize.readU16(buffer);
+        // u16 deployed protocol version
+        int deployed = Serialize.readU16(buffer);
+        System.out.println(String.format("HELLO ser_ver=%d net_compress %d deployed %d", ser_ver,net_compress,deployed));
+        // u32 supported auth methods
+        // std::string username that should be used for legacy hash (for proper casing)
+
+    }
+
+    // clientpackethandler.cpp Client::handleCommand_BlockData(NetworkPacket* pkt)
+    // TOCLIENT_BLOCKDATA
+    void handleCommand_BlockData(NetworkPacket networkPacket)
+            throws PacketException
+    {
+        v3s16 p = networkPacket.v3s16();
+
+        // will be used to get vector...
+        // v2s16 p2d = new v2s16(p.X,p.Z);
+
+        System.out.println(String.format(" (X,Y,Z) %d %d %d", p.X, p.Y,p.Z));
+        //
+        networkPacket.addOffset(6);
+
+        // FIXME get it from handshake
+        int version = 28;
+
+        // Should be a MapBlock
+        MapBlock block = new MapBlock();
+        block.deSerialize(networkPacket.getByteBuffer(),version);
+
+        // now we have a block ! what to do with it ?
+    }
+
+    void handlePacketCommand(NetworkPacket networkPacket)
+            throws PacketException {
+
+        // consume type and ??? well ... 2
+        int command = Serialize.readU16(networkPacket.getBuffer(),networkPacket.getOffset(),networkPacket.getLength());
+
+        System.out.println(String.format("command %x length %d", command, networkPacket.getLength()));
+
+        networkPacket.addOffset(2);
+        // Original ... toClient - toServer
+        switch (command)
+        {
+            case 0x02:
+            {
+                System.out.println("TOCLIENT_HELLO");
+                handleCommand_Hello(networkPacket);
+            }
+            break;
+            case 0x20:
+            {
+                System.out.println("TOCLIENT_BLOCKDATA");
+                handleCommand_BlockData(networkPacket);
+            }
+            break;
+            case 0x4f:
+            {
+                //TOCLIENT_SET_SKY = 0x4f,
+                System.out.println("TOCLIENT_SET_SKY");
+            }
+            break;
+        }
+
+    }
+
+    void handlePacketType_Original(NetworkPacket networkPacket)
+            throws PacketException {
+
+        // eat original type 1.
+        networkPacket.addOffset(1);
+        handlePacketCommand(networkPacket);
+    }
+
+    void handlePacketType_Split(NetworkPacket networkPacket)
+            throws PacketException {
+
+        int channel = networkPacket.getChannel();
+        if ( channel < incomingChanneleSplitBuffer.length) {
+            IncomingSplitBuffer splitBuffer = incomingChanneleSplitBuffer[channel];
+            if ( splitBuffer == null )
+            {
+                splitBuffer = new IncomingSplitBuffer();
+                incomingChanneleSplitBuffer[channel] = splitBuffer;
+            }
+            if ( splitBuffer != null ) {
+                BufferedPacket bufferedPacket = splitBuffer.insert(networkPacket);
+                if ( bufferedPacket != null ) {
+                    // well should handle it.
+                    System.out.println("Reassembled packet size " + bufferedPacket.m_data.length);
+                    // reset it.
+                    incomingChanneleSplitBuffer[channel] = new IncomingSplitBuffer();
+                    handleBufferedPacket(bufferedPacket);
+                }
+            }
+        }
+        else {
+            throw new PacketException("invalid channel " + channel);
+        }
+
+
+    }
+
+    void handleBufferedPacket(BufferedPacket bufferedPacket)
+            throws PacketException
+    {
+        // FIXME, why a BufferedPacket anyway since we finaly need a NetworkPacket ?
+        NetworkPacket networkPacket = new NetworkPacket(0,0,0, PacketType.PACKET_TYPE_ORIGINAL,bufferedPacket.m_data, bufferedPacket.size());
+        networkPacket.addOffset(BufferedPacket.BASE_HEADER_SIZE);
+        handlePacketCommand(networkPacket);
+    }
+
+    void fromServer(byte[] buffer, int length)
+            throws PacketException
+    {
+        System.out.print(" <- ");
+        NetworkPacket networkPacket = handleAny(buffer,length);
+
+        switch (networkPacket.packetType)
+        {
+            case PACKET_TYPE_CONTROL:
+                //
+                handlePacketType_Control(networkPacket);
+                break;
+            case PACKET_TYPE_RELIABLE:
+                //
+                handlePacketType_Reliable(networkPacket);
+                break;
+            case PACKET_TYPE_ORIGINAL:
+                handlePacketType_Original(networkPacket);
+                break;
+            case PACKET_TYPE_SPLIT:
+                handlePacketType_Split(networkPacket);
+                break;
+            default: // error
+                throw new PacketException("unknown type");
+        }
+
+    }
+
+    void fromClient(byte[] buffer, int length)
+            throws PacketException
+    {
+        System.out.print(" -> ");
+        handleAny(buffer,length);
+    }
+
+}

java/org/artisanlogiciel/games/minetest/net/PacketType.java

@@ -0,0 +1,27 @@
+package org.artisanlogiciel.games.minetest.net;
+
+public enum PacketType {
+    PACKET_TYPE_CONTROL,
+    PACKET_TYPE_ORIGINAL,
+    PACKET_TYPE_SPLIT,
+    PACKET_TYPE_RELIABLE,
+    PACKET_TYPE_ERROR;
+
+    static PacketType getPacketType(int value)
+    {
+        switch (value)
+        {
+            case 0:
+                return PACKET_TYPE_CONTROL;
+            case 1:
+                return PACKET_TYPE_ORIGINAL;
+            case 2:
+                return PACKET_TYPE_SPLIT;
+            case 3:
+                return PACKET_TYPE_RELIABLE;
+            default:
+                return PACKET_TYPE_ERROR;
+        }
+    }
+
+}

java/org/artisanlogiciel/games/minetest/net/ReliablePacketBuffer.java

@@ -0,0 +1,20 @@
+package org.artisanlogiciel.games.minetest.net;
+
+import org.artisanlogiciel.games.minetest.core.PacketException;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class ReliablePacketBuffer {
+
+    List<BufferedPacket> m_list = new LinkedList<>();
+
+    void insert(BufferedPacket packet, int nextExpected)
+    throws PacketException
+    {
+        //
+        int seqNum = packet.getSeqNum();
+        m_list.add(packet);
+    }
+
+}