io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionUtil Maven / Gradle / Ivy

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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you 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:
 *
 *   https://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 io.netty.handler.codec.http.websocketx.extensions;

import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaderValues;
import io.netty.handler.codec.http.HttpHeaders;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public final class WebSocketExtensionUtil {

    private static final String EXTENSION_SEPARATOR = ",";
    private static final String PARAMETER_SEPARATOR = ";";
    private static final char PARAMETER_EQUAL = '=';

    private static final Pattern PARAMETER = Pattern.compile("^([^=]+)(=[\\\"]?([^\\\"]+)[\\\"]?)?$");

    static boolean isWebsocketUpgrade(HttpHeaders headers) {
        //this contains check does not allocate an iterator, and most requests are not upgrades
        //so we do the contains check first before checking for specific values
        return headers.contains(HttpHeaderNames.UPGRADE) &&
                headers.containsValue(HttpHeaderNames.CONNECTION, HttpHeaderValues.UPGRADE, true) &&
                headers.contains(HttpHeaderNames.UPGRADE, HttpHeaderValues.WEBSOCKET, true);
    }

    public static List extractExtensions(String extensionHeader) {
        String[] rawExtensions = extensionHeader.split(EXTENSION_SEPARATOR);
        if (rawExtensions.length > 0) {
            List extensions = new ArrayList(rawExtensions.length);
            for (String rawExtension : rawExtensions) {
                String[] extensionParameters = rawExtension.split(PARAMETER_SEPARATOR);
                String name = extensionParameters[0].trim();
                Map parameters;
                if (extensionParameters.length > 1) {
                    parameters = new HashMap(extensionParameters.length - 1);
                    for (int i = 1; i < extensionParameters.length; i++) {
                        String parameter = extensionParameters[i].trim();
                        Matcher parameterMatcher = PARAMETER.matcher(parameter);
                        if (parameterMatcher.matches() && parameterMatcher.group(1) != null) {
                            parameters.put(parameterMatcher.group(1), parameterMatcher.group(3));
                        }
                    }
                } else {
                    parameters = Collections.emptyMap();
                }
                extensions.add(new WebSocketExtensionData(name, parameters));
            }
            return extensions;
        } else {
            return Collections.emptyList();
        }
    }

    static String computeMergeExtensionsHeaderValue(String userDefinedHeaderValue,
                                                    List extraExtensions) {
        List userDefinedExtensions =
          userDefinedHeaderValue != null ?
            extractExtensions(userDefinedHeaderValue) :
            Collections.emptyList();

        for (WebSocketExtensionData userDefined: userDefinedExtensions) {
            WebSocketExtensionData matchingExtra = null;
            int i;
            for (i = 0; i < extraExtensions.size(); i ++) {
                WebSocketExtensionData extra = extraExtensions.get(i);
                if (extra.name().equals(userDefined.name())) {
                    matchingExtra = extra;
                    break;
                }
            }
            if (matchingExtra == null) {
                extraExtensions.add(userDefined);
            } else {
                // merge with higher precedence to user defined parameters
                Map mergedParameters = new HashMap(matchingExtra.parameters());
                mergedParameters.putAll(userDefined.parameters());
                extraExtensions.set(i, new WebSocketExtensionData(matchingExtra.name(), mergedParameters));
            }
        }

        StringBuilder sb = new StringBuilder(150);

        for (WebSocketExtensionData data: extraExtensions) {
            sb.append(data.name());
            for (Entry parameter : data.parameters().entrySet()) {
                sb.append(PARAMETER_SEPARATOR);
                sb.append(parameter.getKey());
                if (parameter.getValue() != null) {
                    sb.append(PARAMETER_EQUAL);
                    sb.append(parameter.getValue());
                }
            }
            sb.append(EXTENSION_SEPARATOR);
        }

        if (!extraExtensions.isEmpty()) {
            sb.setLength(sb.length() - EXTENSION_SEPARATOR.length());
        }

        return sb.toString();
    }

    private WebSocketExtensionUtil() {
        // Unused
    }
}