Add IP discovery.

Before a client wants to join a network, it may send a HTTP "ping"
request to a known participant. The participant will send a HTTP "pong"
request in response, which informs the client of its IP address.

The IP address of a client is automatically retrieved from the first
HTTP request received by Jetty.

8 files changed, 91 insertions, 48 deletions

diff --git a/jsonrpc/src/main/java/com/orbekk/rpc/App.java b/jsonrpc/src/main/java/com/orbekk/rpc/App.java
index d92003e..0e9dce3 100644
--- a/jsonrpc/src/main/java/com/orbekk/rpc/App.java
+++ b/jsonrpc/src/main/java/com/orbekk/rpc/App.java
@@ -28,7 +28,7 @@ public class App {
                 SameService.class);   
     
         Server server = new Server(port);
-        RpcHandler rpcHandler = new RpcHandler(jsonServer, service);
+        RpcHandler rpcHandler = new RpcHandler(jsonServer, sameState);
         server.setHandler(rpcHandler);
 
         try {
diff --git a/jsonrpc/src/main/java/com/orbekk/rpc/Client.java b/jsonrpc/src/main/java/com/orbekk/rpc/Client.java
index ea63fd7..2ec6c89 100644
--- a/jsonrpc/src/main/java/com/orbekk/rpc/Client.java
+++ b/jsonrpc/src/main/java/com/orbekk/rpc/Client.java
@@ -5,6 +5,7 @@ import com.orbekk.same.ConnectionManagerImpl;
 import com.orbekk.same.SameState;
 import com.orbekk.same.SameService;
 import com.orbekk.same.SameServiceImpl;
+import com.orbekk.net.HttpUtil;
 import java.net.MalformedURLException;
 import java.net.URL;
 import org.eclipse.jetty.server.Server;
@@ -33,7 +34,7 @@ public class Client {
                 SameService.class);   
     
         Server server = new Server(port);
-        RpcHandler rpcHandler = new RpcHandler(jsonServer, service);
+        RpcHandler rpcHandler = new RpcHandler(jsonServer, sameState);
         server.setHandler(rpcHandler);
 
         try {
@@ -42,11 +43,20 @@ public class Client {
             System.out.println("Could not start jetty server.");
             e.printStackTrace();
         }
+
+        while (sameState.getUrl() == null) {
+            HttpUtil.sendHttpRequest(remoteAddr + "ping?port=" + port);
+            try {
+                Thread.sleep(500);
+            } catch (InterruptedException e) {
+                // Ignore interrupt in wait loop.
+            }
+        }
         
         SameService remoteService = connections.getConnection(remoteAddr);
         remoteService.notifyNetwork("NoNetwork");
         remoteService.participateNetwork("FirstNetwork",
-                sameState.getClientId(), "", port);
+                sameState.getClientId(), sameState.getUrl());
 
         try {
             server.join();
diff --git a/jsonrpc/src/main/java/com/orbekk/rpc/RpcHandler.java b/jsonrpc/src/main/java/com/orbekk/rpc/RpcHandler.java
index 39676fe..0bafad4 100644
--- a/jsonrpc/src/main/java/com/orbekk/rpc/RpcHandler.java
+++ b/jsonrpc/src/main/java/com/orbekk/rpc/RpcHandler.java
@@ -1,34 +1,52 @@
 package com.orbekk.rpc;
 
+import com.googlecode.jsonrpc4j.JsonRpcServer;
+import com.orbekk.net.HttpUtil;
+import com.orbekk.same.UrlReceiver;
 import java.io.IOException;
-
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-
 import org.eclipse.jetty.server.Request;
 import org.eclipse.jetty.server.handler.AbstractHandler;
-
-import com.googlecode.jsonrpc4j.JsonRpcServer;
-import com.orbekk.same.CallerInfoListener;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class RpcHandler extends AbstractHandler {
+    private Logger logger = LoggerFactory.getLogger(getClass());
     private JsonRpcServer rpcServer;
-    private CallerInfoListener callerInfoListener;
+    private UrlReceiver urlReceiver;
     
     public RpcHandler(JsonRpcServer rpcServer,
-            CallerInfoListener callerInfoListener) {
+            UrlReceiver urlReceiver) {
         this.rpcServer = rpcServer;
-        this.callerInfoListener = callerInfoListener;
+        this.urlReceiver = urlReceiver;
     }
     
     @Override
     public synchronized void handle(String target, Request baseRequest,
             HttpServletRequest request, HttpServletResponse response)
             throws IOException, ServletException {
-        if (callerInfoListener != null) {
-            callerInfoListener.setCaller(request.getRemoteAddr());
+        logger.info("Handling request to target: " + target);
+
+        if (urlReceiver != null) {
+            String sameServiceUrl = "http://" + request.getLocalAddr() + 
+                ":" + request.getLocalPort() + "/SameService.json";
+            urlReceiver.setUrl(sameServiceUrl);
+            urlReceiver = null;
+        }
+
+        if (target.equals("/ping")) {
+            int remotePort = Integer.parseInt(request.getParameter("port"));
+            String pongUrl = "http://" + request.getRemoteAddr() + ":" +
+                remotePort + "/pong";
+            logger.info("Got ping. Sending pong to {}", pongUrl);
+            HttpUtil.sendHttpRequest(pongUrl);
+        } else if (target.equals("/pong")) {
+            logger.info("Received pong from {}", request.getRemoteAddr());
+        } else {
+            rpcServer.handle(request, response);
         }
-        rpcServer.handle(request, response);
+        baseRequest.setHandled(true);
     }
 }
diff --git a/jsonrpc/src/main/java/com/orbekk/same/CallerInfoListener.java b/jsonrpc/src/main/java/com/orbekk/same/CallerInfoListener.java
deleted file mode 100644
index e3ccfea..0000000
--- a/jsonrpc/src/main/java/com/orbekk/same/CallerInfoListener.java
+++ /dev/null
@@ -1,11 +0,0 @@
-package com.orbekk.same;
-
-/**
- * An interface to get notified of the current caller.
- *
- * This interface is needed because jsonrpc4j does not pass the
- * HttpServletRequest to the service implementation.
- */
-public interface CallerInfoListener {
-    void setCaller(String callerIp);
-}
diff --git a/jsonrpc/src/main/java/com/orbekk/same/SameService.java b/jsonrpc/src/main/java/com/orbekk/same/SameService.java
index 0a261a8..76e9035 100644
--- a/jsonrpc/src/main/java/com/orbekk/same/SameService.java
+++ b/jsonrpc/src/main/java/com/orbekk/same/SameService.java
@@ -13,14 +13,9 @@ public interface SameService {
 
     /**
      * A request from the callee to participate in 'networkName'.
-     *
-     * A client may not know its URL. If the url parameter is empty,
-     * use info from the HttpServletRequest.
-     *
-     * TODO: Always pass a valid URL and get rid of the port parameter.
      */
     void participateNetwork(String networkName, String clientId,
-            String url, int remotePort);
+            String url);
 
     /**
      * Notification of participation in network.
diff --git a/jsonrpc/src/main/java/com/orbekk/same/SameServiceImpl.java b/jsonrpc/src/main/java/com/orbekk/same/SameServiceImpl.java
index e7484c1..533a055 100644
--- a/jsonrpc/src/main/java/com/orbekk/same/SameServiceImpl.java
+++ b/jsonrpc/src/main/java/com/orbekk/same/SameServiceImpl.java
@@ -6,34 +6,31 @@ import java.util.LinkedList;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class SameServiceImpl implements SameService, CallerInfoListener {
+public class SameServiceImpl implements SameService {
     private Logger logger = LoggerFactory.getLogger(getClass());
     private SameState sameState;
-    private String currentCallerIp;
 
     public SameServiceImpl(SameState sameState) {
         this.sameState = sameState;
     }
 
     @Override
-    public void setCaller(String callerIp) {
-        currentCallerIp = callerIp;
-    }
-
-    @Override
     public void notifyNetwork(String networkName) {
         logger.info("Notification from network " + networkName);
     }
 
     @Override
     public void participateNetwork(String networkName, String clientId,
-            String url, int remotePort) {
+            String url) {
         if (!networkName.equals(sameState.getNetworkName())) {
             logger.warn("Client tried to join {}, but network name is {}.",
                     networkName, sameState.getNetworkName());
+            return;
         }
-        if (url.equals("")) {
-            url = "http://" + currentCallerIp + ":" + remotePort;
+        if (clientId.equals("") || url.equals("")) {
+            logger.warn("Missing client info: ClientId({}), URL({}).",
+                    clientId, url);
+            return;
         }
         sameState.addParticipant(clientId, url);
     }
diff --git a/jsonrpc/src/main/java/com/orbekk/same/SameState.java b/jsonrpc/src/main/java/com/orbekk/same/SameState.java
index d7dd3dc..c097a0d 100644
--- a/jsonrpc/src/main/java/com/orbekk/same/SameState.java
+++ b/jsonrpc/src/main/java/com/orbekk/same/SameState.java
@@ -10,14 +10,30 @@ import org.slf4j.LoggerFactory;
  *
  * This class manages the current state of the Same protocol.
  */
-public class SameState extends Thread {
+public class SameState extends Thread implements UrlReceiver {
     private Logger logger = LoggerFactory.getLogger(getClass());
     private ConnectionManager connections;
     private List<String> participants = new LinkedList<String>();
     private String currentState = "";
     private String networkName;
-    // The client id of this participant.
+
+    /**
+     * The client id of this participant.
+     */
     private String clientId;
+
+    /**
+     * The URL of this participant.
+     *
+     * Important note: Our URL is unknown initially. Url is null until we
+     * receive our first request. The URL is then taken to be the target URL
+     * from the request.
+     */
+    private String url = null;
+
+    /**
+     * Stopping condition for this thread.
+     */
     private boolean stopped = false;
 
     /**
@@ -48,12 +64,20 @@ public class SameState extends Thread {
         return currentState;
     }
 
+    public String getUrl() {
+        return url;
+    }
+
+    @Override
+    public void setUrl(String url) {
+        logger.info("My URL is {}", url);
+        this.url = url;
+    }
+
     public synchronized void addParticipant(String clientId, String url) {
-        synchronized(this) {
-            logger.info("Add pending participant: {} ({})", clientId, url);
-            pendingParticipants.add(url);
-            notifyAll();
-        }
+        logger.info("PendingParticipant.add: {} ({})", clientId, url);
+        pendingParticipants.add(url);
+        notifyAll();
     }
 
     private synchronized void handleNewParticipants() {
diff --git a/jsonrpc/src/main/java/com/orbekk/same/UrlReceiver.java b/jsonrpc/src/main/java/com/orbekk/same/UrlReceiver.java
new file mode 100644
index 0000000..31a0276
--- /dev/null
+++ b/jsonrpc/src/main/java/com/orbekk/same/UrlReceiver.java
@@ -0,0 +1,10 @@
+package com.orbekk.same;
+
+/**
+ * An interface to get notified of the URL to this computer.
+ *
+ * This interface is used to reliably obtain the URL of this host.
+ */
+public interface UrlReceiver {
+    void setUrl(String url);
+}