vaadin-framework/server/src/main/java/com/vaadin/server/ConnectorResourceHandler.java

/*
 * Copyright 2000-2018 Vaadin Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.vaadin.server;

import java.io.IOException;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.http.HttpServletResponse;

import com.vaadin.shared.ApplicationConstants;
import com.vaadin.ui.UI;
import com.vaadin.util.CurrentInstance;

public class ConnectorResourceHandler implements RequestHandler {
    // APP/connector/[uiid]/[cid]/[filename.xyz]
    private static final String CONNECTOR_RESOURCE_PREFIX = "/"
            + ApplicationConstants.APP_PATH + "/"
            + ConnectorResource.CONNECTOR_PATH + "/";
    private static final Pattern CONNECTOR_RESOURCE_PATTERN = Pattern
            .compile("^" + CONNECTOR_RESOURCE_PREFIX + "(\\d+)/(\\d+)/(.*)");

    private static Logger getLogger() {
        return Logger.getLogger(ConnectorResourceHandler.class.getName());

    }

    @Override
    public boolean handleRequest(VaadinSession session, VaadinRequest request,
            VaadinResponse response) throws IOException {
        String requestPath = request.getPathInfo();
        if (requestPath == null
                || !requestPath.startsWith(CONNECTOR_RESOURCE_PREFIX)) {
            return false;
        }
        Matcher matcher = CONNECTOR_RESOURCE_PATTERN.matcher(requestPath);
        if (!matcher.matches()) {
            // This is a connector resource request based on the prefix but the
            // pattern did not match
            warnAboutInvalidURLEncoding(requestPath);
            response.sendError(HttpServletResponse.SC_NOT_FOUND,
                    "Connector resource not found");
            return true;
        }
        String uiId = matcher.group(1);
        String cid = matcher.group(2);
        String key = matcher.group(3);

        session.lock();
        UI ui;
        ClientConnector connector;
        try {
            ui = session.getUIById(Integer.parseInt(uiId));
            if (ui == null) {
                return error(request, response,
                        "Ignoring connector request for no-existent root "
                                + uiId);
            }

            connector = ui.getConnectorTracker().getConnector(cid);
            if (connector == null) {
                return error(request, response,
                        "Ignoring connector request for no-existent connector "
                                + cid + " in root " + uiId);
            }

        } finally {
            session.unlock();
        }

        Map<Class<?>, CurrentInstance> oldInstances = CurrentInstance
                .setCurrent(ui);
        try {
            if (!connector.handleConnectorRequest(request, response, key)) {
                return error(request, response,
                        connector.getClass().getSimpleName() + " ("
                                + connector.getConnectorId()
                                + ") did not handle connector request for "
                                + key);
            }
        } catch (Exception e) {
            session.lock();
            try {
                session.getCommunicationManager()
                        .handleConnectorRelatedException(connector, e);
            } finally {
                session.unlock();
            }
        } finally {
            CurrentInstance.restoreInstances(oldInstances);
        }

        return true;
    }

    private boolean loggedDecodingWarning = false;

    private void warnAboutInvalidURLEncoding(String requestPath) {
        if (requestPath.contains("\n") || requestPath.indexOf(0x85) != -1) {
            // What, path info should not contain a new line or UTF-8 Next Line
            // (NEL) character, but it does in
            // Tomcat 7 with default configuration in some cases (URL is encoded
            // by the browser as UTF-8 and decoded as ISO-8859-1 by Tomcat)

            if (!loggedDecodingWarning) {
                loggedDecodingWarning = true;
                getLogger().warning(
                        "Request path contains a new line character. This typically means that the server is incorrectly configured to use something else than UTF-8 for URL decoding (requestPath: "
                                + requestPath + ")");
            }
        }
    }

    private static boolean error(VaadinRequest request, VaadinResponse response,
            String logMessage) throws IOException {
        getLogger().log(Level.WARNING, logMessage);
        response.sendError(HttpServletResponse.SC_NOT_FOUND,
                request.getPathInfo() + " can not be found");

        // Request handled (though not in a nice way)
        return true;
    }
}