Refine Throwable handling in spring-websocket

This commit lowers the level of Throwable handling in parts of
spring-websocket which now handle Exception instead and allow any Error
to propagate.

Closes gh-24075

spring-websocket/src/main/java/org/springframework/web/socket/adapter/jetty/JettyWebSocketHandlerAdapter.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -71,7 +71,7 @@ public class JettyWebSocketHandlerAdapter {
 			this.wsSession.initializeNativeSession(session);
 			this.webSocketHandler.afterConnectionEstablished(this.wsSession);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}
@@ -82,7 +82,7 @@ public class JettyWebSocketHandlerAdapter {
 		try {
 			this.webSocketHandler.handleMessage(this.wsSession, message);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}
@@ -93,7 +93,7 @@ public class JettyWebSocketHandlerAdapter {
 		try {
 			this.webSocketHandler.handleMessage(this.wsSession, message);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}
@@ -106,7 +106,7 @@ public class JettyWebSocketHandlerAdapter {
 			try {
 				this.webSocketHandler.handleMessage(this.wsSession, message);
 			}
-			catch (Throwable ex) {
+			catch (Exception ex) {
 				ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 			}
 		}
@@ -118,7 +118,7 @@ public class JettyWebSocketHandlerAdapter {
 		try {
 			this.webSocketHandler.afterConnectionClosed(this.wsSession, closeStatus);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			if (logger.isWarnEnabled()) {
 				logger.warn("Unhandled exception after connection closed for " + this, ex);
 			}
@@ -130,7 +130,7 @@ public class JettyWebSocketHandlerAdapter {
 		try {
 			this.webSocketHandler.handleTransportError(this.wsSession, cause);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}

spring-websocket/src/main/java/org/springframework/web/socket/adapter/standard/StandardWebSocketHandlerAdapter.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -103,7 +103,7 @@ public class StandardWebSocketHandlerAdapter extends Endpoint {
 		try {
 			this.handler.afterConnectionEstablished(this.wsSession);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}
@@ -113,7 +113,7 @@ public class StandardWebSocketHandlerAdapter extends Endpoint {
 		try {
 			this.handler.handleMessage(this.wsSession, textMessage);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}
@@ -123,7 +123,7 @@ public class StandardWebSocketHandlerAdapter extends Endpoint {
 		try {
 			this.handler.handleMessage(this.wsSession, binaryMessage);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}
@@ -133,7 +133,7 @@ public class StandardWebSocketHandlerAdapter extends Endpoint {
 		try {
 			this.handler.handleMessage(this.wsSession, pongMessage);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}
@@ -144,7 +144,7 @@ public class StandardWebSocketHandlerAdapter extends Endpoint {
 		try {
 			this.handler.afterConnectionClosed(this.wsSession, closeStatus);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			if (logger.isWarnEnabled()) {
 				logger.warn("Unhandled on-close exception for " + this.wsSession, ex);
 			}
@@ -156,7 +156,7 @@ public class StandardWebSocketHandlerAdapter extends Endpoint {
 		try {
 			this.handler.handleTransportError(this.wsSession, exception);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			ExceptionWebSocketHandlerDecorator.tryCloseWithError(this.wsSession, ex, logger);
 		}
 	}

spring-websocket/src/main/java/org/springframework/web/socket/handler/ExceptionWebSocketHandlerDecorator.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -47,7 +47,7 @@ public class ExceptionWebSocketHandlerDecorator extends WebSocketHandlerDecorato
 		try {
 			getDelegate().afterConnectionEstablished(session);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			tryCloseWithError(session, ex, logger);
 		}
 	}
@@ -57,7 +57,7 @@ public class ExceptionWebSocketHandlerDecorator extends WebSocketHandlerDecorato
 		try {
 			getDelegate().handleMessage(session, message);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			tryCloseWithError(session, ex, logger);
 		}
 	}
@@ -67,7 +67,7 @@ public class ExceptionWebSocketHandlerDecorator extends WebSocketHandlerDecorato
 		try {
 			getDelegate().handleTransportError(session, exception);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			tryCloseWithError(session, ex, logger);
 		}
 	}
@@ -77,7 +77,7 @@ public class ExceptionWebSocketHandlerDecorator extends WebSocketHandlerDecorato
 		try {
 			getDelegate().afterConnectionClosed(session, closeStatus);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			if (logger.isWarnEnabled()) {
 				logger.warn("Unhandled exception after connection closed for " + this, ex);
 			}

spring-websocket/src/main/java/org/springframework/web/socket/server/support/AbstractHandshakeHandler.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -157,7 +157,7 @@ public abstract class AbstractHandshakeHandler implements HandshakeHandler, Life
 			Class<?> clazz = ClassUtils.forName(className, AbstractHandshakeHandler.class.getClassLoader());
 			return (RequestUpgradeStrategy) ReflectionUtils.accessibleConstructor(clazz).newInstance();
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			throw new IllegalStateException(
 					"Failed to instantiate RequestUpgradeStrategy: " + className, ex);
 		}

spring-websocket/src/main/java/org/springframework/web/socket/server/support/HandshakeInterceptorChain.java

@@ -77,7 +77,7 @@ public class HandshakeInterceptorChain {
 			try {
 				interceptor.afterHandshake(request, response, this.wsHandler, failure);
 			}
-			catch (Throwable ex) {
+			catch (Exception ex) {
 				if (logger.isWarnEnabled()) {
 					logger.warn(interceptor + " threw exception in afterHandshake: " + ex);
 				}

spring-websocket/src/main/java/org/springframework/web/socket/server/support/WebSocketHttpRequestHandler.java

@@ -171,7 +171,7 @@ public class WebSocketHttpRequestHandler implements HttpRequestHandler, Lifecycl
 		catch (HandshakeFailureException ex) {
 			failure = ex;
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			failure = new HandshakeFailureException("Uncaught failure for request " + request.getURI(), ex);
 		}
 		finally {

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/AbstractClientSockJsSession.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -244,7 +244,7 @@ public abstract class AbstractClientSockJsSession implements WebSocketSession {
 				this.webSocketHandler.afterConnectionEstablished(this);
 				this.connectFuture.set(this);
 			}
-			catch (Throwable ex) {
+			catch (Exception ex) {
 				if (logger.isErrorEnabled()) {
 					logger.error("WebSocketHandler.afterConnectionEstablished threw exception in " + this, ex);
 				}
@@ -293,7 +293,7 @@ public abstract class AbstractClientSockJsSession implements WebSocketSession {
 				try {
 					this.webSocketHandler.handleMessage(this, new TextMessage(message));
 				}
-				catch (Throwable ex) {
+				catch (Exception ex) {
 					logger.error("WebSocketHandler.handleMessage threw an exception on " + frame + " in " + this, ex);
 				}
 			}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java

@@ -118,7 +118,7 @@ public class RestTemplateXhrTransport extends AbstractXhrTransport {
 					getRestTemplate().execute(receiveUrl, HttpMethod.POST, requestCallback, responseExtractor);
 					requestCallback = requestCallbackAfterHandshake;
 				}
-				catch (Throwable ex) {
+				catch (Exception ex) {
 					if (!connectFuture.isDone()) {
 						connectFuture.setException(ex);
 					}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/SockJsClient.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -260,7 +260,7 @@ public class SockJsClient implements WebSocketClient, Lifecycle {
 			ServerInfo serverInfo = getServerInfo(sockJsUrlInfo, getHttpRequestHeaders(headers));
 			createRequest(sockJsUrlInfo, headers, serverInfo).connect(handler, connectFuture);
 		}
-		catch (Throwable exception) {
+		catch (Exception exception) {
 			if (logger.isErrorEnabled()) {
 				logger.error("Initial SockJS \"Info\" request to server failed, url=" + url, exception);
 			}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/support/SockJsHttpRequestHandler.java

 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -133,7 +133,7 @@ public class SockJsHttpRequestHandler
 		try {
 			this.sockJsService.handleRequest(request, response, getSockJsPath(servletRequest), this.webSocketHandler);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			throw new SockJsException("Uncaught failure in SockJS request, uri=" + request.getURI(), ex);
 		}
 	}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/TransportHandlingSockJsService.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -215,10 +215,10 @@ public class TransportHandlingSockJsService extends AbstractSockJsService implem
 		catch (HandshakeFailureException ex) {
 			failure = ex;
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			failure = new HandshakeFailureException("Uncaught failure for request " + request.getURI(), ex);
 		}
-			finally {
+		finally {
 			if (failure != null) {
 				chain.applyAfterHandshake(request, response, failure);
 				throw failure;
@@ -316,7 +316,7 @@ public class TransportHandlingSockJsService extends AbstractSockJsService implem
 		catch (SockJsException ex) {
 			failure = ex;
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			failure = new SockJsException("Uncaught failure for request " + request.getURI(), sessionId, ex);
 		}
 		finally {

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/handler/AbstractHttpReceivingTransportHandler.java

 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,7 +72,7 @@ public abstract class AbstractHttpReceivingTransportHandler extends AbstractTran
 			}
 			return;
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			logger.error("Failed to read message", ex);
 			handleReadError(response, "Failed to read message(s)", sockJsSession.getId());
 			return;

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/handler/WebSocketTransportHandler.java

@@ -124,7 +124,7 @@ public class WebSocketTransportHandler extends AbstractTransportHandler
 			wsHandler = new SockJsWebSocketHandler(getServiceConfig(), wsHandler, sockJsSession);
 			this.handshakeHandler.doHandshake(request, response, wsHandler, sockJsSession.getAttributes());
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			sockJsSession.tryCloseWithSockJsTransportError(ex, CloseStatus.SERVER_ERROR);
 			throw new SockJsTransportFailureException("WebSocket handshake failure", wsSession.getId(), ex);
 		}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java

@@ -324,7 +324,7 @@ public abstract class AbstractSockJsSession implements SockJsSession {
 		try {
 			writeFrameInternal(frame);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			logWriteFrameFailure(ex);
 			try {
 				// Force disconnect (so we won't try to send close frame)
@@ -388,7 +388,7 @@ public abstract class AbstractSockJsSession implements SockJsSession {
 					undelivered.remove(0);
 				}
 			}
-			catch (Throwable ex) {
+			catch (Exception ex) {
 				throw new SockJsMessageDeliveryException(this.id, undelivered, ex);
 			}
 		}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/WebSocketServerSockJsSession.java

@@ -166,7 +166,7 @@ public class WebSocketServerSockJsSession extends AbstractSockJsSession implemen
 				scheduleHeartbeat();
 				this.openFrameSent = true;
 			}
-			catch (Throwable ex) {
+			catch (Exception ex) {
 				tryCloseWithSockJsTransportError(ex, CloseStatus.SERVER_ERROR);
 			}
 		}
@@ -186,7 +186,7 @@ public class WebSocketServerSockJsSession extends AbstractSockJsSession implemen
 		try {
 			messages = getSockJsServiceConfig().getMessageCodec().decode(payload);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
 			logger.error("Broken data received. Terminating WebSocket connection abruptly", ex);
 			tryCloseWithSockJsTransportError(ex, CloseStatus.BAD_DATA);
 			return;