Always access the listener from the same synchronized context

ibauersachs · ibauersachs · commit 19e5a124cf7d · 2019-10-27T20:24:28.000+01:00
diff --git a/src/main/java/org/xbill/DNS/ExtendedResolver.java b/src/main/java/org/xbill/DNS/ExtendedResolver.java
@@ -129,7 +129,9 @@ public Message start() throws IOException {
 
     /* Start an asynchronous resolution */
     public void startAsync(ResolverListener listener) {
-      this.listener = listener;
+      synchronized (this) {
+        this.listener = listener;
+      }
       send(0);
     }
 
@@ -140,6 +142,7 @@ public void startAsync(ResolverListener listener) {
     @Override
     public void receiveMessage(Object id, Message m) {
       log.debug("received message");
+      ResolverListener listenerCopy;
       synchronized (this) {
         if (done) {
           return;
@@ -149,9 +152,11 @@ public void receiveMessage(Object id, Message m) {
         if (listener == null) {
           notifyAll();
           return;
+        } else {
+          listenerCopy = listener;
         }
       }
-      listener.receiveMessage(this, response);
+      listenerCopy.receiveMessage(this, response);
     }
 
     /*
@@ -161,6 +166,7 @@ public void receiveMessage(Object id, Message m) {
     @Override
     public void handleException(Object id, Exception e) {
       log.debug("resolving failed", e);
+      ResolverListener listenerCopy = null;
       synchronized (this) {
         outstanding--;
         if (done) {
@@ -225,6 +231,8 @@ public void handleException(Object id, Exception e) {
           if (listener == null) {
             notifyAll();
             return;
+          } else {
+            listenerCopy = listener;
           }
         }
         if (!done) {
@@ -233,9 +241,9 @@ public void handleException(Object id, Exception e) {
       }
       /* If we're done and this is asynchronous, call the callback. */
       if (!(thrown instanceof Exception)) {
-        thrown = new RuntimeException(thrown.getMessage());
+        thrown = new RuntimeException(thrown);
       }
-      listener.handleException(this, (Exception) thrown);
+      listenerCopy.handleException(this, (Exception) thrown);
     }
   }
 

Original file line number	Diff line number	Diff line change
`@@ -129,7 +129,9 @@ public Message start() throws IOException {`
`129`	`129`
`130`	`130`	`/* Start an asynchronous resolution */`
`131`	`131`	`public void startAsync(ResolverListener listener) {`
`132`		`- this.listener = listener;`
	`132`	`+ synchronized (this) {`
	`133`	`+ this.listener = listener;`
	`134`	`+ }`
`133`	`135`	`send(0);`
`134`	`136`	`}`
`135`	`137`
`@@ -140,6 +142,7 @@ public void startAsync(ResolverListener listener) {`
`140`	`142`	`@Override`
`141`	`143`	`public void receiveMessage(Object id, Message m) {`
`142`	`144`	`log.debug("received message");`
	`145`	`+ ResolverListener listenerCopy;`
`143`	`146`	`synchronized (this) {`
`144`	`147`	`if (done) {`
`145`	`148`	`return;`
`@@ -149,9 +152,11 @@ public void receiveMessage(Object id, Message m) {`
`149`	`152`	`if (listener == null) {`
`150`	`153`	`notifyAll();`
`151`	`154`	`return;`
	`155`	`+ } else {`
	`156`	`+ listenerCopy = listener;`
`152`	`157`	`}`
`153`	`158`	`}`
`154`		`- listener.receiveMessage(this, response);`
	`159`	`+ listenerCopy.receiveMessage(this, response);`
`155`	`160`	`}`
`156`	`161`
`157`	`162`	`/*`
`@@ -161,6 +166,7 @@ public void receiveMessage(Object id, Message m) {`
`161`	`166`	`@Override`
`162`	`167`	`public void handleException(Object id, Exception e) {`
`163`	`168`	`log.debug("resolving failed", e);`
	`169`	`+ ResolverListener listenerCopy = null;`
`164`	`170`	`synchronized (this) {`
`165`	`171`	`outstanding--;`
`166`	`172`	`if (done) {`
`@@ -225,6 +231,8 @@ public void handleException(Object id, Exception e) {`
`225`	`231`	`if (listener == null) {`
`226`	`232`	`notifyAll();`
`227`	`233`	`return;`
	`234`	`+ } else {`
	`235`	`+ listenerCopy = listener;`
`228`	`236`	`}`
`229`	`237`	`}`
`230`	`238`	`if (!done) {`
`@@ -233,9 +241,9 @@ public void handleException(Object id, Exception e) {`
`233`	`241`	`}`
`234`	`242`	`/* If we're done and this is asynchronous, call the callback. */`
`235`	`243`	`if (!(thrown instanceof Exception)) {`
`236`		`- thrown = new RuntimeException(thrown.getMessage());`
	`244`	`+ thrown = new RuntimeException(thrown);`
`237`	`245`	`}`
`238`		`- listener.handleException(this, (Exception) thrown);`
	`246`	`+ listenerCopy.handleException(this, (Exception) thrown);`
`239`	`247`	`}`
`240`	`248`	`}`
`241`	`249`