Networking code, untested

domain/build.gradle

@@ -8,5 +8,6 @@ repositories {
 }
 
 dependencies {
+    compile 'org.slf4j:slf4j-api:1.7.12'
     testCompile group: 'junit', name: 'junit', version: '4.11'
 }

domain/src/main/java/ch/dissem/bitmessage/Context.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2015 Christian Basler
+ *
+ * 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 ch.dissem.bitmessage;
+
+import ch.dissem.bitmessage.ports.AddressRepository;
+import ch.dissem.bitmessage.ports.Inventory;
+import ch.dissem.bitmessage.ports.NetworkMessageReceiver;
+import ch.dissem.bitmessage.ports.NetworkMessageSender;
+
+/**
+ * Created by chris on 05.04.15.
+ */
+public class Context {
+    public static final int CURRENT_VERSION = 3;
+
+    private static Context instance;
+
+    private Inventory inventory;
+    private AddressRepository addressRepo;
+    private NetworkMessageSender sender;
+    private NetworkMessageReceiver receiver;
+
+    private Context(Inventory inventory, AddressRepository addressRepo,
+                    NetworkMessageSender sender, NetworkMessageReceiver receiver) {
+        this.inventory = inventory;
+        this.addressRepo = addressRepo;
+        this.sender = sender;
+        this.receiver = receiver;
+    }
+
+    public static void init(Inventory inventory, AddressRepository addressRepository, NetworkMessageSender sender, NetworkMessageReceiver receiver) {
+        instance = new Context(inventory, addressRepository, sender, receiver);
+    }
+
+    public static Context getInstance() {
+        return instance;
+    }
+
+    public Inventory getInventory() {
+        return inventory;
+    }
+
+    public AddressRepository getAddressRepository() {
+        return addressRepo;
+    }
+}

domain/src/main/java/ch/dissem/bitmessage/entity/Addr.java

@@ -22,12 +22,13 @@ import ch.dissem.bitmessage.utils.Encode;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 
 /**
  * The 'addr' command holds a list of known active Bitmessage nodes.
  */
-public class Addr implements Command {
+public class Addr implements MessagePayload {
     private final List<NetworkAddress> addresses;
 
     private Addr(Builder builder) {
@@ -35,8 +36,12 @@ public class Addr implements Command {
     }
 
     @Override
-    public String getCommand() {
-        return "addr";
+    public Command getCommand() {
+        return Command.ADDR;
+    }
+
+    public List<NetworkAddress> getAddresses() {
+        return addresses;
     }
 
     @Override
@@ -53,6 +58,11 @@ public class Addr implements Command {
         public Builder() {
         }
 
+        public Builder addresses(Collection<NetworkAddress> addresses){
+            this.addresses.addAll(addresses);
+            return this;
+        }
+
         public Builder addAddress(final NetworkAddress address) {
             this.addresses.add(address);
             return this;

domain/src/main/java/ch/dissem/bitmessage/entity/GetData.java

@@ -27,7 +27,7 @@ import java.util.List;
 /**
  * The 'getdata' command is used to request objects from a node.
  */
-public class GetData implements Command {
+public class GetData implements MessagePayload {
     List<InventoryVector> inventory;
 
     private GetData(Builder builder) {
@@ -35,8 +35,12 @@ public class GetData implements Command {
     }
 
     @Override
-    public String getCommand() {
-        return "getdata";
+    public Command getCommand() {
+        return Command.GETDATA;
+    }
+
+    public List<InventoryVector> getInventory() {
+        return inventory;
     }
 
     @Override

domain/src/main/java/ch/dissem/bitmessage/entity/Inv.java

@@ -27,16 +27,20 @@ import java.util.List;
 /**
  * The 'inv' command holds up to 50000 inventory vectors, i.e. hashes of inventory items.
  */
-public class Inv implements Command {
+public class Inv implements MessagePayload {
     private List<InventoryVector> inventory;
 
     private Inv(Builder builder) {
         inventory = builder.inventory;
     }
 
+    public List<InventoryVector> getInventory() {
+        return inventory;
+    }
+
     @Override
-    public String getCommand() {
-        return "inv";
+    public Command getCommand() {
+        return Command.INV;
     }
 
     @Override

domain/src/main/java/ch/dissem/bitmessage/entity/MessagePayload.java

@@ -19,6 +19,10 @@ package ch.dissem.bitmessage.entity;
 /**
  * A command can hold a network message payload
  */
-public interface Command extends Streamable {
-    String getCommand();
+public interface MessagePayload extends Streamable {
+    Command getCommand();
+
+    enum Command {
+        VERSION, VERACK, ADDR, INV, GETDATA, OBJECT
+    }
 }

domain/src/main/java/ch/dissem/bitmessage/entity/NetworkMessage.java

@@ -16,7 +16,6 @@
 
 package ch.dissem.bitmessage.entity;
 
-import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 import ch.dissem.bitmessage.utils.Encode;
 
 import java.io.ByteArrayOutputStream;
@@ -39,12 +38,9 @@ public class NetworkMessage implements Streamable {
     public final static int MAGIC = 0xE9BEB4D9;
     public final static byte[] MAGIC_BYTES = ByteBuffer.allocate(4).putInt(MAGIC).array();
 
-    private final NetworkAddress targetNode;
+    private final MessagePayload payload;
 
-    private final Command payload;
-
-    public NetworkMessage(NetworkAddress target, Command payload) {
-        this.targetNode = target;
+    public NetworkMessage(MessagePayload payload) {
         this.payload = payload;
     }
 
@@ -59,22 +55,19 @@ public class NetworkMessage implements Streamable {
     /**
      * The actual data, a message or an object. Not to be confused with objectPayload.
      */
-    public Command getPayload() {
+    public MessagePayload getPayload() {
         return payload;
     }
 
-    public NetworkAddress getTargetNode() {
-        return targetNode;
-    }
-
     @Override
     public void write(OutputStream stream) throws IOException {
         // magic
         Encode.int32(MAGIC, stream);
 
         // ASCII string identifying the packet content, NULL padded (non-NULL padding results in packet rejected)
-        stream.write(payload.getCommand().getBytes("ASCII"));
-        for (int i = payload.getCommand().length(); i < 12; i++) {
+        String command = payload.getCommand().name().toLowerCase();
+        stream.write(command.getBytes("ASCII"));
+        for (int i = command.length(); i < 12; i++) {
             stream.write('\0');
         }
 

domain/src/main/java/ch/dissem/bitmessage/entity/ObjectMessage.java

@@ -17,6 +17,7 @@
 package ch.dissem.bitmessage.entity;
 
 import ch.dissem.bitmessage.entity.payload.ObjectPayload;
+import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 import ch.dissem.bitmessage.utils.Encode;
 
 import java.io.IOException;
@@ -25,7 +26,7 @@ import java.io.OutputStream;
 /**
  * The 'object' command sends an object that is shared throughout the network.
  */
-public class ObjectMessage implements Command {
+public class ObjectMessage implements MessagePayload {
     private long nonce;
     private long expiresTime;
     private long objectType;
@@ -47,8 +48,17 @@ public class ObjectMessage implements Command {
     }
 
     @Override
-    public String getCommand() {
-        return "object";
+    public Command getCommand() {
+        return Command.OBJECT;
+    }
+
+    public ObjectPayload getPayload() {
+        return payload;
+    }
+
+    public InventoryVector getInventoryVector() {
+        // TODO
+        return null;
     }
 
     @Override

domain/src/main/java/ch/dissem/bitmessage/entity/VerAck.java

@@ -22,10 +22,10 @@ import java.io.OutputStream;
 /**
  * The 'verack' command answers a 'version' command, accepting the other node's version.
  */
-public class VerAck implements Command {
+public class VerAck implements MessagePayload {
     @Override
-    public String getCommand() {
-        return "verack";
+    public Command getCommand() {
+        return Command.VERACK;
     }
 
     @Override

domain/src/main/java/ch/dissem/bitmessage/entity/Version.java

@@ -16,6 +16,7 @@
 
 package ch.dissem.bitmessage.entity;
 
+import ch.dissem.bitmessage.Context;
 import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 import ch.dissem.bitmessage.utils.Encode;
 
@@ -26,8 +27,7 @@ import java.util.Random;
 /**
  * The 'version' command advertises this node's latest supported protocol version upon initiation.
  */
-public class Version implements Command {
-    public static final int CURRENT = 3;
+public class Version implements MessagePayload {
     /**
      * Identifies protocol version being used by the node. Should equal 3. Nodes should disconnect if the remote node's
      * version is lower but continue with the connection if it is higher.
@@ -71,6 +71,17 @@ public class Version implements Command {
      */
     private final long[] streamNumbers;
 
+    private Version(Builder builder) {
+        version = builder.version;
+        services = builder.services;
+        timestamp = builder.timestamp;
+        addrRecv = builder.addrRecv;
+        addrFrom = builder.addrFrom;
+        nonce = builder.nonce;
+        userAgent = builder.userAgent;
+        streamNumbers = builder.streamNumbers;
+    }
+
     public int getVersion() {
         return version;
     }
@@ -99,24 +110,13 @@ public class Version implements Command {
         return userAgent;
     }
 
-    public long[] getStreamNumbers() {
+    public long[] getStreams() {
         return streamNumbers;
     }
 
-    private Version(Builder builder) {
-        version = builder.version;
-        services = builder.services;
-        timestamp = builder.timestamp;
-        addrRecv = builder.addrRecv;
-        addrFrom = builder.addrFrom;
-        nonce = builder.nonce;
-        userAgent = builder.userAgent;
-        streamNumbers = builder.streamNumbers;
-    }
-
     @Override
-    public String getCommand() {
-        return "version";
+    public Command getCommand() {
+        return Command.VERSION;
     }
 
     @Override
@@ -146,7 +146,7 @@ public class Version implements Command {
         }
 
         public Builder defaults() {
-            version = CURRENT;
+            version = Context.CURRENT;
             services = 1;
             timestamp = System.currentTimeMillis() / 1000;
             nonce = new Random().nextInt();

domain/src/main/java/ch/dissem/bitmessage/factory/V3MessageFactory.java

@@ -40,7 +40,7 @@ class V3MessageFactory {
             byte[] payloadBytes = Decode.bytes(stream, length);
 
             if (testChecksum(checksum, payloadBytes)) {
-                Command payload = getPayload(command, new ByteArrayInputStream(payloadBytes), length);
+                MessagePayload payload = getPayload(command, new ByteArrayInputStream(payloadBytes), length);
                 return new NetworkMessage(payload);
             } else {
                 throw new IOException("Checksum failed for message '" + command + "'");
@@ -49,7 +49,7 @@ class V3MessageFactory {
         return null;
     }
 
-    private Command getPayload(String command, InputStream stream, int length) throws IOException {
+    private MessagePayload getPayload(String command, InputStream stream, int length) throws IOException {
         switch (command) {
             case "version":
                 return parseVersion(stream);

domain/src/main/java/ch/dissem/bitmessage/ports/AddressRepository.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2015 Christian Basler
+ *
+ * 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 ch.dissem.bitmessage.ports;
+
+import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
+
+import java.util.List;
+
+/**
+ * Stores and provides known peers.
+ */
+public interface AddressRepository {
+    List<NetworkAddress> getKnownAddresses(int limit, long... streams);
+
+    void offerAddresses(List<NetworkAddress> addresses);
+}

domain/src/main/java/ch/dissem/bitmessage/ports/Inventory.java

@@ -16,6 +16,7 @@
 
 package ch.dissem.bitmessage.ports;
 
+import ch.dissem.bitmessage.entity.ObjectMessage;
 import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
 
@@ -25,13 +26,13 @@ import java.util.List;
  * The Inventory stores and retrieves objects, cleans up outdated objects and can tell which objects are still missing.
  */
 public interface Inventory {
-    public List<InventoryVector> getInventory();
+    public List<InventoryVector> getInventory(long... streams);
 
     public List<InventoryVector> getMissing(List<InventoryVector> offer);
 
-    public ObjectPayload getObject(InventoryVector vector);
+    public ObjectMessage getObject(InventoryVector vector);
 
-    public void storeObject(InventoryVector vector, ObjectPayload object);
+    public void storeObject(ObjectMessage object);
 
     public void cleanup();
 }

domain/src/main/java/ch/dissem/bitmessage/ports/NetworkMessageReceiver.java

@@ -17,6 +17,7 @@
 package ch.dissem.bitmessage.ports;
 
 import ch.dissem.bitmessage.entity.NetworkMessage;
+import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 
 import java.io.IOException;
@@ -25,11 +26,11 @@ import java.io.IOException;
  * Handles incoming messages
  */
 public interface NetworkMessageReceiver {
-    public void registerListener(int port) throws IOException;
+    void registerListener(int port, MessageListener listener) throws IOException;
 
-    public void registerListener(NetworkAddress node, MessageListener listener) throws IOException;
+    void registerListener(NetworkAddress node, MessageListener listener) throws IOException;
 
-    public static interface MessageListener {
-        public void receive(NetworkMessage message);
+    interface MessageListener {
+        void receive(ObjectPayload payload);
     }
 }

domain/src/main/java/ch/dissem/bitmessage/ports/NetworkMessageSender.java

@@ -16,12 +16,12 @@
 
 package ch.dissem.bitmessage.ports;
 
-import ch.dissem.bitmessage.entity.NetworkMessage;
+import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 
 /**
  * Sends messages
  */
 public interface NetworkMessageSender {
-    public void send(NetworkAddress node, NetworkMessage message);
+    void send(NetworkAddress node, ObjectPayload payload);
 }

domain/src/main/java/ch/dissem/bitmessage/utils/AddressFormatException.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2015 Christian Basler
+ *
+ * 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 ch.dissem.bitmessage.utils;
+
+/**
+ * Indicates an illegal Bitmessage address
+ */
+public class AddressFormatException extends RuntimeException {
+    public AddressFormatException(String message) {
+        super(message);
+    }
+}

domain/src/main/java/ch/dissem/bitmessage/utils/Base58.java

@@ -1,4 +1,5 @@
 /*
+ * Copyright 2011 Google Inc.
  * Copyright 2015 Christian Basler
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -16,17 +17,151 @@
 
 package ch.dissem.bitmessage.utils;
 
+import java.io.UnsupportedEncodingException;
+
 /**
  * Base58 encoder and decoder
  */
 public class Base58 {
     private static char[] ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz".toCharArray();
 
-    public static String encode(byte[] input) {
-        return null; // TODO
+    private static final int[] INDEXES = new int[128];
+
+    static {
+        for (int i = 0; i < INDEXES.length; i++) {
+            INDEXES[i] = -1;
+        }
+        for (int i = 0; i < ALPHABET.length; i++) {
+            INDEXES[ALPHABET[i]] = i;
+        }
     }
 
-    public static byte[] decode(String input) {
-        return null; // TODO
+    /**
+     * Encodes the given bytes in base58. No checksum is appended.
+     */
+    public static String encode(byte[] input) {
+        if (input.length == 0) {
+            return "";
+        }
+        input = copyOfRange(input, 0, input.length);
+        // Count leading zeroes.
+        int zeroCount = 0;
+        while (zeroCount < input.length && input[zeroCount] == 0) {
+            ++zeroCount;
+        }
+        // The actual encoding.
+        byte[] temp = new byte[input.length * 2];
+        int j = temp.length;
+
+        int startAt = zeroCount;
+        while (startAt < input.length) {
+            byte mod = divmod58(input, startAt);
+            if (input[startAt] == 0) {
+                ++startAt;
+            }
+            temp[--j] = (byte) ALPHABET[mod];
+        }
+
+        // Strip extra '1' if there are some after decoding.
+        while (j < temp.length && temp[j] == ALPHABET[0]) {
+            ++j;
+        }
+        // Add as many leading '1' as there were leading zeros.
+        while (--zeroCount >= 0) {
+            temp[--j] = (byte) ALPHABET[0];
+        }
+
+        byte[] output = copyOfRange(temp, j, temp.length);
+        try {
+            return new String(output, "US-ASCII");
+        } catch (UnsupportedEncodingException e) {
+            throw new RuntimeException(e);  // Cannot happen.
+        }
+    }
+
+    public static byte[] decode(String input) throws AddressFormatException {
+        if (input.length() == 0) {
+            return new byte[0];
+        }
+        byte[] input58 = new byte[input.length()];
+        // Transform the String to a base58 byte sequence
+        for (int i = 0; i < input.length(); ++i) {
+            char c = input.charAt(i);
+
+            int digit58 = -1;
+            if (c >= 0 && c < 128) {
+                digit58 = INDEXES[c];
+            }
+            if (digit58 < 0) {
+                throw new AddressFormatException("Illegal character " + c + " at " + i);
+            }
+
+            input58[i] = (byte) digit58;
+        }
+        // Count leading zeroes
+        int zeroCount = 0;
+        while (zeroCount < input58.length && input58[zeroCount] == 0) {
+            ++zeroCount;
+        }
+        // The encoding
+        byte[] temp = new byte[input.length()];
+        int j = temp.length;
+
+        int startAt = zeroCount;
+        while (startAt < input58.length) {
+            byte mod = divmod256(input58, startAt);
+            if (input58[startAt] == 0) {
+                ++startAt;
+            }
+
+            temp[--j] = mod;
+        }
+        // Do no add extra leading zeroes, move j to first non null byte.
+        while (j < temp.length && temp[j] == 0) {
+            ++j;
+        }
+
+        return copyOfRange(temp, j - zeroCount, temp.length);
+    }
+
+    //
+    // number -> number / 58, returns number % 58
+    //
+    private static byte divmod58(byte[] number, int startAt) {
+        int remainder = 0;
+        for (int i = startAt; i < number.length; i++) {
+            int digit256 = (int) number[i] & 0xFF;
+            int temp = remainder * 256 + digit256;
+
+            number[i] = (byte) (temp / 58);
+
+            remainder = temp % 58;
+        }
+
+        return (byte) remainder;
+    }
+
+    //
+    // number -> number / 256, returns number % 256
+    //
+    private static byte divmod256(byte[] number58, int startAt) {
+        int remainder = 0;
+        for (int i = startAt; i < number58.length; i++) {
+            int digit58 = (int) number58[i] & 0xFF;
+            int temp = remainder * 58 + digit58;
+
+            number58[i] = (byte) (temp / 256);
+
+            remainder = temp % 256;
+        }
+
+        return (byte) remainder;
+    }
+
+    private static byte[] copyOfRange(byte[] source, int from, int to) {
+        byte[] range = new byte[to - from];
+        System.arraycopy(source, from, range, 0, range.length);
+
+        return range;
     }
 }

networking/build.gradle

@@ -9,5 +9,7 @@ repositories {
 
 dependencies {
     compile ':domain'
+    compile 'com.google.guava:guava-concurrent:r03'
+    testCompile 'org.slf4j:slf4j-simple:1.7.12'
     testCompile 'junit:junit:4.11'
 }

networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java

@@ -0,0 +1,189 @@
+/*
+ * Copyright 2015 Christian Basler
+ *
+ * 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 ch.dissem.bitmessage.networking;
+
+import ch.dissem.bitmessage.Context;
+import ch.dissem.bitmessage.entity.*;
+import ch.dissem.bitmessage.entity.valueobject.InventoryVector;
+import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
+import ch.dissem.bitmessage.factory.Factory;
+import ch.dissem.bitmessage.ports.NetworkMessageReceiver.MessageListener;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.Socket;
+import java.net.SocketTimeoutException;
+import java.util.List;
+import java.util.Queue;
+import java.util.concurrent.ConcurrentLinkedDeque;
+
+import static ch.dissem.bitmessage.networking.Connection.State.*;
+
+/**
+ * A connection to a specific node
+ */
+public class Connection implements Runnable {
+    private final static Logger LOG = LoggerFactory.getLogger(Connection.class);
+
+    private Context ctx;
+
+    private State state;
+    private Socket socket;
+    private InputStream in;
+    private OutputStream out;
+    private MessageListener listener;
+
+    private int version;
+    private long[] streams;
+
+    private NetworkAddress host;
+    private NetworkAddress node;
+
+    private Queue<MessagePayload> sendingQueue = new ConcurrentLinkedDeque<>();
+
+    public Connection(State state, Socket socket, MessageListener listener) throws IOException {
+        this.ctx = Context.getInstance();
+        this.state = state;
+        this.socket = socket;
+        this.in = socket.getInputStream();
+        this.out = socket.getOutputStream();
+        this.listener = listener;
+        this.host = new NetworkAddress.Builder().ipv6(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0).port(0).build();
+        this.node = new NetworkAddress.Builder().ip(socket.getInetAddress()).port(socket.getPort()).build();
+    }
+
+    @Override
+    public void run() {
+        if (state == CLIENT) {
+            send(new Version.Builder().defaults().addrFrom(host).addrRecv(node).build());
+        }
+        while (state != DISCONNECTED) {
+            try {
+                NetworkMessage msg = Factory.getNetworkMessage(version, in);
+                switch (state) {
+                    case ACTIVE:
+                        receiveMessage(msg.getPayload());
+                        break;
+
+                    default:
+                        switch (msg.getPayload().getCommand()) {
+                            case VERSION:
+                                Version payload = (Version) msg.getPayload();
+                                if (payload.getVersion() >= Context.CURRENT_VERSION) {
+                                    this.version = payload.getVersion();
+                                    this.streams = payload.getStreams();
+                                    send(new VerAck());
+                                    if (state == SERVER) {
+                                        state = ACTIVE;
+                                    }
+                                } else {
+                                    disconnect();
+                                }
+                                break;
+                            case VERACK:
+                                if (state == CLIENT) {
+                                    sendAddresses();
+                                    sendInventory();
+
+                                    state = ACTIVE;
+                                } else {
+                                    send(new Version.Builder().defaults().addrFrom(host).addrRecv(node).build());
+                                }
+                                break;
+                            default:
+                                throw new RuntimeException("Command 'version' or 'verack' expected, but was "
+                                        + msg.getPayload().getCommand());
+                        }
+                }
+            } catch (SocketTimeoutException e) {
+                if (state == ACTIVE) {
+                    for (MessagePayload msg = sendingQueue.poll(); msg != null; msg = sendingQueue.poll()) {
+                        send(msg);
+                    }
+                }
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    private void receiveMessage(MessagePayload messagePayload) {
+        switch (messagePayload.getCommand()) {
+            case INV:
+                Inv inv = (Inv) messagePayload;
+                List<InventoryVector> missing = ctx.getInventory().getMissing(inv.getInventory());
+                send(new GetData.Builder().inventory(missing).build());
+                break;
+            case GETDATA:
+                GetData getData = (GetData) messagePayload;
+                for (InventoryVector iv : getData.getInventory()) {
+                    ObjectMessage om = ctx.getInventory().getObject(iv);
+                    sendingQueue.offer(om);
+                }
+                break;
+            case OBJECT:
+                ObjectMessage objectMessage = (ObjectMessage) messagePayload;
+                ctx.getInventory().storeObject(objectMessage);
+                listener.receive(objectMessage.getPayload());
+                break;
+            case ADDR:
+                Addr addr = (Addr) messagePayload;
+                ctx.getAddressRepository().offerAddresses(addr.getAddresses());
+                break;
+            case VERACK:
+            case VERSION:
+                throw new RuntimeException("Unexpectedly received '" + messagePayload.getCommand() + "' command");
+        }
+    }
+
+    private void sendAddresses() {
+        List<NetworkAddress> addresses = ctx.getAddressRepository().getKnownAddresses(1000, streams);
+        send(new Addr.Builder().addresses(addresses).build());
+    }
+
+    private void sendInventory() {
+        List<InventoryVector> inventory = ctx.getInventory().getInventory(streams);
+        for (int i = 0; i < inventory.size(); i += 50000) {
+            sendingQueue.offer(new Inv.Builder()
+                    .inventory(inventory.subList(i, Math.min(inventory.size(), i + 50000)))
+                    .build());
+        }
+    }
+
+    private void disconnect() {
+        try {
+            state = DISCONNECTED;
+            socket.close();
+        } catch (IOException e) {
+            LOG.debug(e.getMessage(), e);
+        }
+    }
+
+    private void send(MessagePayload payload) {
+        try {
+            new NetworkMessage(payload).write(out);
+        } catch (IOException e) {
+            LOG.error(e.getMessage(), e);
+            disconnect();
+        }
+    }
+
+    public enum State {SERVER, CLIENT, ACTIVE, DISCONNECTED}
+}

networking/src/main/java/ch/dissem/bitmessage/networking/NetworkNode.java

@@ -22,69 +22,68 @@ import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 import ch.dissem.bitmessage.factory.Factory;
 import ch.dissem.bitmessage.ports.NetworkMessageReceiver;
 import ch.dissem.bitmessage.ports.NetworkMessageSender;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-import java.util.concurrent.LinkedBlockingQueue;
+
+import static ch.dissem.bitmessage.networking.Connection.State.CLIENT;
+import static ch.dissem.bitmessage.networking.Connection.State.SERVER;
 
 /**
  * Handles all the networky stuff.
  */
 public class NetworkNode implements NetworkMessageSender, NetworkMessageReceiver {
-    private final BlockingQueue<NetworkMessage> sendingQueue = new LinkedBlockingQueue<>();
-    private final ExecutorService pool;
-
-    private final Map<NetworkAddress, Socket> sockets = new HashMap<>();
-    private final Map<NetworkAddress, Integer> versions = new HashMap<>();
-
+    private final static Logger LOG = LoggerFactory.getLogger(NetworkNode.class);
     /**
      * This is only to be used where it's ignored
      */
     private final static NetworkAddress LOCALHOST = new NetworkAddress.Builder().ipv4(127, 0, 0, 1).port(8444).build();
+    private final ExecutorService pool;
 
     public NetworkNode() {
         pool = Executors.newCachedThreadPool();
 
-        new Thread(new Runnable() {
-            @Override
-            public void run() {
-                while (true) {
-                    try {
-                        NetworkMessage message = sendingQueue.take();
-                        Socket socket = getSocket(message.getTargetNode());
-                        message.write(socket.getOutputStream());
-                    } catch (Exception e) {
-                        e.printStackTrace();
-                    }
-                }
-            }
-        }, "Sender");
+        // TODO: sending
+//        Thread sender = new Thread(new Runnable() {
+//            @Override
+//            public void run() {
+//                while (true) {
+//                    try {
+//                        NetworkMessage message = sendingQueue.take();
+//
+//                        try (Socket socket = getSocket(message.getTargetNode())) {
+//                            message.write(socket.getOutputStream());
+//                        } catch (Exception e) {
+//                            e.printStackTrace();
+//                        }
+//                    } catch (InterruptedException e) {
+//                        // Ignore?
+//                    }
+//                }
+//            }
+//        }, "Sender");
+//        sender.setDaemon(true);
+//        sender.start();
     }
 
     @Override
-    public void registerListener(final int port) throws IOException {
+    public void registerListener(final int port, final MessageListener listener) throws IOException {
         final ServerSocket serverSocket = new ServerSocket(port);
         pool.execute(new Runnable() {
             @Override
             public void run() {
+                NetworkAddress address = null;
                 try {
                     Socket socket = serverSocket.accept();
                     socket.setSoTimeout(20000);
-                    // FIXME: addd to sockets
-                    registerListener(getVersion(null), socket, new MessageListener() {
-                        @Override
-                        public void receive(NetworkMessage message) {
-                            // TODO
-                        }
-                    });
+                    pool.execute(new Connection(SERVER, socket, listener));
                 } catch (IOException e) {
-                    e.printStackTrace();
+                    LOG.debug(e.getMessage(), e);
                 }
             }
         });
@@ -92,60 +91,11 @@ public class NetworkNode implements NetworkMessageSender, NetworkMessageReceiver
 
     @Override
     public void registerListener(final NetworkAddress node, final MessageListener listener) throws IOException {
-        final Socket socket = getSocket(node);
-        final int version = getVersion(node);
-        sendVersion(node);
-        pool.execute(new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    registerListener(version, socket, listener);
-                } catch (IOException e) {
-                    e.printStackTrace();
-                }
-            }
-        });
-    }
-
-    private void sendVersion(NetworkAddress node) {
-        send(node, new NetworkMessage(node, new Version.Builder().defaults().addrFrom(LOCALHOST).addrRecv(node).build()));
-    }
-
-    private void registerListener(int version, Socket socket, MessageListener listener) throws IOException {
-        NetworkMessage message = Factory.getNetworkMessage(version, socket.getInputStream());
-        if (message.getPayload() instanceof Version) {
-            version = ((Version) message.getPayload()).getVersion();
-            synchronized (versions) {
-
-                versions.put(new NetworkAddress.Builder()
-                        .ip(socket.getInetAddress())
-                        .port(socket.getPort())
-                        .build(), version);
-            }
-        }
-        listener.receive(message);
+        pool.execute(new Connection(CLIENT, new Socket(node.toInetAddress(), node.getPort()), listener));
     }
 
     @Override
     public void send(final NetworkAddress node, final NetworkMessage message) {
-        sendingQueue.add(message);
-    }
-
-    private Socket getSocket(NetworkAddress node) throws IOException {
-        synchronized (sockets) {
-            Socket socket = sockets.get(node);
-            if (socket == null) {
-                socket = new Socket(node.toInetAddress(), node.getPort());
-                sockets.put(node, socket);
-            }
-            return socket;
-        }
-    }
-
-    private synchronized int getVersion(NetworkAddress node) {
-        synchronized (versions) {
-            Integer version = versions.get(node);
-            return version == null ? 3 : version;
-        }
+        // TODO: sendingQueue.add(message);
     }
 }

networking/src/test/java/ch/dissem/bitmessage/networking/NetworkNodeTest.java

@@ -18,6 +18,7 @@ package ch.dissem.bitmessage.networking;
 
 import ch.dissem.bitmessage.entity.NetworkMessage;
 import ch.dissem.bitmessage.entity.Version;
+import ch.dissem.bitmessage.entity.payload.ObjectPayload;
 import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 import ch.dissem.bitmessage.ports.NetworkMessageReceiver;
 import org.junit.Test;
@@ -34,12 +35,12 @@ public class NetworkNodeTest {
         NetworkNode net = new NetworkNode();
         net.registerListener(localhost, new NetworkMessageReceiver.MessageListener() {
             @Override
-            public void receive(NetworkMessage message) {
-                System.out.println(message);
+            public void receive(ObjectPayload payload) {
+                System.out.println(payload);
                 baseThread.interrupt();
             }
         });
-        NetworkMessage ver = new NetworkMessage(localhost,
+        NetworkMessage ver = new NetworkMessage(
                 new Version.Builder()
                         .version(3)
                         .services(1)
@@ -49,7 +50,8 @@ public class NetworkNodeTest {
                         .nonce(-1)
                         .userAgent("Test")
                         .streams(1, 2)
-                        .build());
+                        .build()
+        );
         net.send(localhost, ver);
         Thread.sleep(20000);
     }