Java tutorial
/* * Copyright (c) 2014, 2015 Cisco Systems, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.netconf.sal.streams.websockets; import static io.netty.handler.codec.http.HttpHeaders.isKeepAlive; import static io.netty.handler.codec.http.HttpHeaders.setContentLength; import static io.netty.handler.codec.http.HttpHeaders.Names.HOST; import static io.netty.handler.codec.http.HttpMethod.GET; import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST; import static io.netty.handler.codec.http.HttpResponseStatus.FORBIDDEN; import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR; import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.handler.codec.http.DefaultFullHttpResponse; import io.netty.handler.codec.http.FullHttpRequest; import io.netty.handler.codec.http.FullHttpResponse; import io.netty.handler.codec.http.HttpRequest; import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame; import io.netty.handler.codec.http.websocketx.PingWebSocketFrame; import io.netty.handler.codec.http.websocketx.PongWebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory; import io.netty.util.CharsetUtil; import java.io.IOException; import org.opendaylight.netconf.sal.streams.listeners.ListenerAdapter; import org.opendaylight.netconf.sal.streams.listeners.Notificator; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * {@link WebSocketServerHandler} is implementation of {@link SimpleChannelInboundHandler} which allow handle * {@link FullHttpRequest} and {@link WebSocketFrame} messages. */ public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> { private static final Logger logger = LoggerFactory.getLogger(WebSocketServerHandler.class); private WebSocketServerHandshaker handshaker; @Override protected void channelRead0(final ChannelHandlerContext ctx, final Object msg) throws Exception { if (msg instanceof FullHttpRequest) { handleHttpRequest(ctx, (FullHttpRequest) msg); } else if (msg instanceof WebSocketFrame) { handleWebSocketFrame(ctx, (WebSocketFrame) msg); } } /** * Checks if HTTP request method is GET and if is possible to decode HTTP result of request. * * @param ctx * ChannelHandlerContext * @param req * FullHttpRequest */ private void handleHttpRequest(final ChannelHandlerContext ctx, final FullHttpRequest req) throws Exception { // Handle a bad request. if (!req.getDecoderResult().isSuccess()) { sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST)); return; } // Allow only GET methods. if (req.getMethod() != GET) { sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN)); return; } String streamName = Notificator.createStreamNameFromUri(req.getUri()); ListenerAdapter listener = Notificator.getListenerFor(streamName); if (listener != null) { listener.addSubscriber(ctx.channel()); logger.debug("Subscriber successfully registered."); } else { logger.error("Listener for stream with name '{}' was not found.", streamName); sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, INTERNAL_SERVER_ERROR)); } // Handshake WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(getWebSocketLocation(req), null, false); handshaker = wsFactory.newHandshaker(req); if (handshaker == null) { WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel()); } else { handshaker.handshake(ctx.channel(), req); } } /** * Checks response status, send response and close connection if necessary * * @param ctx * ChannelHandlerContext * @param req * HttpRequest * @param res * FullHttpResponse */ private static void sendHttpResponse(final ChannelHandlerContext ctx, final HttpRequest req, final FullHttpResponse res) { // Generate an error page if response getStatus code is not OK (200). if (res.getStatus().code() != 200) { ByteBuf buf = Unpooled.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8); res.content().writeBytes(buf); buf.release(); setContentLength(res, res.content().readableBytes()); } // Send the response and close the connection if necessary. ChannelFuture f = ctx.channel().writeAndFlush(res); if (!isKeepAlive(req) || res.getStatus().code() != 200) { f.addListener(ChannelFutureListener.CLOSE); } } /** * Handles web socket frame. * * @param ctx * {@link ChannelHandlerContext} * @param frame * {@link WebSocketFrame} */ private void handleWebSocketFrame(final ChannelHandlerContext ctx, final WebSocketFrame frame) throws IOException { if (frame instanceof CloseWebSocketFrame) { handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain()); String streamName = Notificator.createStreamNameFromUri(((CloseWebSocketFrame) frame).reasonText()); ListenerAdapter listener = Notificator.getListenerFor(streamName); if (listener != null) { listener.removeSubscriber(ctx.channel()); logger.debug("Subscriber successfully registered."); } Notificator.removeListenerIfNoSubscriberExists(listener); return; } else if (frame instanceof PingWebSocketFrame) { ctx.channel().write(new PongWebSocketFrame(frame.content().retain())); return; } } @Override public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) throws Exception { if (cause instanceof java.nio.channels.ClosedChannelException == false) { // cause.printStackTrace(); } ctx.close(); } /** * Get web socket location from HTTP request. * * @param req * HTTP request from which the location will be returned * @return String representation of web socket location. */ private static String getWebSocketLocation(final HttpRequest req) { return "ws://" + req.headers().get(HOST) + req.getUri(); } }