001/**
002 *
003 * Copyright 2017 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.Map;
021
022import org.jivesoftware.smack.packet.ExtensionElement;
023import org.jivesoftware.smack.packet.Message;
024import org.jivesoftware.smack.util.StringUtils;
025import org.jivesoftware.smack.util.XmlStringBuilder;
026
027public class ExplicitMessageEncryptionElement implements ExtensionElement {
028
029    private static final Map<String, ExplicitMessageEncryptionProtocol> PROTOCOL_LUT = new HashMap<>();
030
031    public static final String ELEMENT = "encryption";
032
033    public static final String NAMESPACE = "urn:xmpp:eme:0";
034
035    public enum ExplicitMessageEncryptionProtocol {
036
037        /**
038         * The encryption method specified in <a href="https://xmpp.org/extensions/xep-0373.html">XEP-0373: OpenPGP for
039         * XMPP</a>.
040         */
041        openpgpV0("urn:xmpp:openpgp:0", "OpenPGP for XMPP (XEP-0373)"),
042
043        otrV0("urn:xmpp:otr:0", "Off-the-Record Messaging (XEP-0364)"),
044
045        omemoVAxolotl("eu.siacs.conversations.axolotl", "OMEMO Multi End Message and Object Encryption (XEP-0384)"),
046
047        legacyOpenPGP("jabber:x:encrypted", "Legacy OpenPGP for XMPP [DANGEROUS, DO NOT USE!]"),
048        ;
049
050        private final String namespace;
051        private final String name;
052
053        ExplicitMessageEncryptionProtocol(String namespace, String name) {
054            this.namespace = namespace;
055            this.name = name;
056            PROTOCOL_LUT.put(namespace, this);
057        }
058
059        public String getNamespace() {
060            return namespace;
061        }
062
063        public String getName() {
064            return name;
065        }
066
067        public static ExplicitMessageEncryptionProtocol from(String namespace) {
068            return PROTOCOL_LUT.get(namespace);
069        }
070    }
071
072    private final String encryptionNamespace;
073
074    private final String name;
075
076    private boolean isUnknownProtocol;
077
078    private ExplicitMessageEncryptionProtocol protocolCache;
079
080    public ExplicitMessageEncryptionElement(ExplicitMessageEncryptionProtocol protocol) {
081        this(protocol.getNamespace(), protocol.getName());
082    }
083
084    public ExplicitMessageEncryptionElement(String encryptionNamespace) {
085        this(encryptionNamespace, null);
086    }
087
088    public ExplicitMessageEncryptionElement(String encryptionNamespace, String name) {
089        this.encryptionNamespace = StringUtils.requireNotNullOrEmpty(encryptionNamespace,
090                        "encryptionNamespace must not be null");
091        this.name = name;
092    }
093
094    public ExplicitMessageEncryptionProtocol getProtocol() {
095        if (protocolCache != null) {
096            return protocolCache;
097        }
098
099        if (isUnknownProtocol) {
100            return null;
101        }
102
103        ExplicitMessageEncryptionProtocol protocol = PROTOCOL_LUT.get(encryptionNamespace);
104        if (protocol == null) {
105            isUnknownProtocol = true;
106            return null;
107        }
108
109        protocolCache = protocol;
110        return protocol;
111    }
112
113    public String getEncryptionNamespace() {
114        return encryptionNamespace;
115    }
116
117    /**
118     * Get the optional name of the encryption method.
119     *
120     * @return the name of the encryption method or <code>null</code>.
121     */
122    public String getName() {
123        return name;
124    }
125
126    @Override
127    public String getElementName() {
128        return ELEMENT;
129    }
130
131    @Override
132    public String getNamespace() {
133        return NAMESPACE;
134    }
135
136    @Override
137    public XmlStringBuilder toXML(String enclosingNamespace) {
138        XmlStringBuilder xml = new XmlStringBuilder(this);
139        xml.attribute("namespace", getEncryptionNamespace());
140        xml.optAttribute("name", getName());
141        xml.closeEmptyElement();
142        return xml;
143    }
144
145    public static ExplicitMessageEncryptionElement from(Message message) {
146        return message.getExtension(ELEMENT, NAMESPACE);
147    }
148}