001/**
002 *
003 * Copyright 2017-2019 Florian Schmaus
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smackx.eme.element;
018
019import java.util.HashMap;
020import java.util.List;
021import java.util.Map;
022
023import javax.xml.namespace.QName;
024
025import org.jivesoftware.smack.packet.ExtensionElement;
026import org.jivesoftware.smack.packet.Message;
027import org.jivesoftware.smack.packet.MessageBuilder;
028import org.jivesoftware.smack.packet.MessageView;
029import org.jivesoftware.smack.util.StringUtils;
030import org.jivesoftware.smack.util.XmlStringBuilder;
031
032public class ExplicitMessageEncryptionElement implements ExtensionElement {
033
034    private static final Map<String, ExplicitMessageEncryptionProtocol> PROTOCOL_LUT = new HashMap<>();
035
036    public static final String ELEMENT = "encryption";
037
038    public static final String NAMESPACE = "urn:xmpp:eme:0";
039
040    public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
041
042    public enum ExplicitMessageEncryptionProtocol {
043
044        /**
045         * The encryption method specified in <a href="https://xmpp.org/extensions/xep-0373.html">XEP-0373: OpenPGP for
046         * XMPP</a>.
047         */
048        openpgpV0("urn:xmpp:openpgp:0", "OpenPGP for XMPP (XEP-0373)"),
049
050        otrV0("urn:xmpp:otr:0", "Off-the-Record Messaging (XEP-0364)"),
051
052        omemoVAxolotl("eu.siacs.conversations.axolotl", "OMEMO Multi End Message and Object Encryption (XEP-0384)"),
053
054        legacyOpenPGP("jabber:x:encrypted", "Legacy OpenPGP for XMPP [DANGEROUS, DO NOT USE!]"),
055        ;
056
057        private final String namespace;
058        private final String name;
059
060        ExplicitMessageEncryptionProtocol(String namespace, String name) {
061            this.namespace = namespace;
062            this.name = name;
063            PROTOCOL_LUT.put(namespace, this);
064        }
065
066        public String getNamespace() {
067            return namespace;
068        }
069
070        public String getName() {
071            return name;
072        }
073
074        public static ExplicitMessageEncryptionProtocol from(String namespace) {
075            return PROTOCOL_LUT.get(namespace);
076        }
077    }
078
079    private final String encryptionNamespace;
080
081    private final String name;
082
083    private boolean isUnknownProtocol;
084
085    private ExplicitMessageEncryptionProtocol protocolCache;
086
087    public ExplicitMessageEncryptionElement(ExplicitMessageEncryptionProtocol protocol) {
088        this(protocol.getNamespace(), protocol.getName());
089    }
090
091    public ExplicitMessageEncryptionElement(String encryptionNamespace) {
092        this(encryptionNamespace, null);
093    }
094
095    public ExplicitMessageEncryptionElement(String encryptionNamespace, String name) {
096        this.encryptionNamespace = StringUtils.requireNotNullNorEmpty(encryptionNamespace,
097                        "encryptionNamespace must not be null");
098        this.name = name;
099    }
100
101    public ExplicitMessageEncryptionProtocol getProtocol() {
102        if (protocolCache != null) {
103            return protocolCache;
104        }
105
106        if (isUnknownProtocol) {
107            return null;
108        }
109
110        ExplicitMessageEncryptionProtocol protocol = PROTOCOL_LUT.get(encryptionNamespace);
111        if (protocol == null) {
112            isUnknownProtocol = true;
113            return null;
114        }
115
116        protocolCache = protocol;
117        return protocol;
118    }
119
120    public String getEncryptionNamespace() {
121        return encryptionNamespace;
122    }
123
124    /**
125     * Get the optional name of the encryption method.
126     *
127     * @return the name of the encryption method or <code>null</code>.
128     */
129    public String getName() {
130        return name;
131    }
132
133    @Override
134    public String getElementName() {
135        return ELEMENT;
136    }
137
138    @Override
139    public String getNamespace() {
140        return NAMESPACE;
141    }
142
143    @Override
144    public XmlStringBuilder toXML(org.jivesoftware.smack.packet.XmlEnvironment enclosingNamespace) {
145        XmlStringBuilder xml = new XmlStringBuilder(this);
146        xml.attribute("namespace", getEncryptionNamespace());
147        xml.optAttribute("name", getName());
148        xml.closeEmptyElement();
149        return xml;
150    }
151
152    public static ExplicitMessageEncryptionElement from(Message message) {
153        return message.getExtension(ExplicitMessageEncryptionElement.class);
154    }
155
156    /**
157     * Return true, if the {@code message} already contains an EME element with the specified {@code protocolNamespace}.
158     *
159     * @param message message
160     * @param protocolNamespace namespace
161     * @return true if message has EME element for that namespace, otherwise false
162     */
163    public static boolean hasProtocol(MessageView message, String protocolNamespace) {
164        List<ExplicitMessageEncryptionElement> emeElements = message
165                .getExtensions(ExplicitMessageEncryptionElement.class);
166
167        for (ExplicitMessageEncryptionElement emeElement : emeElements) {
168            if (emeElement.getEncryptionNamespace().equals(protocolNamespace)) {
169                return true;
170            }
171        }
172
173        return false;
174    }
175
176    /**
177     * Return true, if the {@code message} already contains an EME element with the specified protocol namespace.
178     *
179     * @param message message
180     * @param protocol protocol
181     * @return true if message has EME element for that namespace, otherwise false
182     */
183    public static boolean hasProtocol(MessageView message, ExplicitMessageEncryptionProtocol protocol) {
184        return hasProtocol(message, protocol.namespace);
185    }
186
187    /**
188     * Add an EME element containing the specified {@code protocol} namespace to the message.
189     * In case there is already an element with that protocol, we do nothing.
190     *
191     * @param message a message builder.
192     * @param protocol encryption protocol
193     */
194    public static void set(MessageBuilder message, ExplicitMessageEncryptionProtocol protocol) {
195        if (!hasProtocol(message, protocol.namespace)) {
196            message.addExtension(new ExplicitMessageEncryptionElement(protocol));
197        }
198    }
199}