issue #4: prevent connections to self, select random nodes to connect to

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

@@ -52,6 +52,7 @@ public class InternalContext {
     private final int port;
     private long networkNonceTrialsPerByte = 1000;
     private long networkExtraBytes = 1000;
+    private long clientNonce;
 
     public InternalContext(BitmessageContext.Builder builder) {
         this.inventory = builder.inventory;
@@ -60,6 +61,7 @@ public class InternalContext {
         this.addressRepository = builder.addressRepo;
         this.messageRepository = builder.messageRepo;
         this.proofOfWorkEngine = builder.proofOfWorkEngine;
+        this.clientNonce = Security.randomNonce();
 
         port = builder.port;
         streams = builder.streams;
@@ -212,6 +214,14 @@ public class InternalContext {
         }
     }
 
+    public long getClientNonce() {
+        return clientNonce;
+    }
+
+    public void setClientNonce(long clientNonce) {
+        this.clientNonce = clientNonce;
+    }
+
     public interface ContextHolder {
         void setContext(InternalContext context);
     }

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

@@ -230,4 +230,8 @@ public class Security {
             throw new RuntimeException(e);
         }
     }
+
+    public static long randomNonce() {
+        return RANDOM.nextLong();
+    }
 }