add a failed download state

core/src/main/groovy/com/muwire/core/download/BadHashException.groovy

@@ -0,0 +1,25 @@
+package com.muwire.core.download
+
+class BadHashException extends Exception {
+
+    public BadHashException() {
+        super();
+    }
+
+    public BadHashException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+
+    public BadHashException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public BadHashException(String message) {
+        super(message);
+    }
+
+    public BadHashException(Throwable cause) {
+        super(cause);
+    }
+    
+}

core/src/main/groovy/com/muwire/core/download/DownloadSession.groovy

@@ -127,11 +127,8 @@ class DownloadSession {
             byte [] hash = digest.digest()
             byte [] expected = new byte[32]
             System.arraycopy(infoHash.getHashList(), piece * 32, expected, 0, 32)    
-            if (hash != expected) {
-                log.warning("hash mismatch")
-                endpoint.close()
-                return
-            }
+            if (hash != expected) 
+                throw new BadHashException()
             
             pieces.markDownloaded(piece)        
         } finally {

core/src/main/groovy/com/muwire/core/download/Downloader.groovy

@@ -2,13 +2,18 @@ package com.muwire.core.download
 
 import com.muwire.core.InfoHash
 import com.muwire.core.connection.Endpoint
+
+import java.util.logging.Level
+
 import com.muwire.core.Constants
 import com.muwire.core.connection.I2PConnector
 
+import groovy.util.logging.Log
 import net.i2p.data.Destination
 
+@Log
 public class Downloader {
-    public enum DownloadState { CONNECTING, DOWNLOADING, FINISHED }
+    public enum DownloadState { CONNECTING, DOWNLOADING, FAILED, FINISHED }
     
     private final File file
     private final Pieces pieces
@@ -43,14 +48,22 @@ public class Downloader {
     }
     
     void download() {
-        Endpoint endpoint = connector.connect(destination)
-        currentState = DownloadState.DOWNLOADING
-        while(!pieces.isComplete()) {
-            currentSession = new DownloadSession(pieces, infoHash, endpoint, file, pieceSize, length)
-            currentSession.request()
+        Endpoint endpoint = null
+        try {
+            endpoint = connector.connect(destination)
+            currentState = DownloadState.DOWNLOADING
+            while(!pieces.isComplete()) {
+                currentSession = new DownloadSession(pieces, infoHash, endpoint, file, pieceSize, length)
+                currentSession.request()
+            }
+            currentState = DownloadState.FINISHED
+        } catch (Exception bad) {
+            log.log(Level.WARNING,"Exception while downloading",bad)
+            if (currentState != DownloadState.FINISHED)
+                currentState = DownloadState.FAILED
+        } finally {
+            endpoint?.close()
         }
-        currentState = DownloadState.FINISHED
-        endpoint.close()
     }
     
     public long donePieces() {