001/**
002 *
003 * Copyright the original author or authors
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.bytestreams.ibb.packet;
018
019import org.jivesoftware.smack.packet.ExtensionElement;
020import org.jivesoftware.smack.packet.IQ.IQChildElementXmlStringBuilder;
021import org.jivesoftware.smack.util.XmlStringBuilder;
022import org.jivesoftware.smack.util.stringencoder.Base64;
023
024/**
025 * Represents a chunk of data of an In-Band Bytestream within an IQ stanza or a
026 * message stanza.
027 *
028 * @author Henning Staib
029 */
030public class DataPacketExtension implements ExtensionElement {
031
032    /**
033     * The element name of the data stanza extension.
034     */
035    public static final String ELEMENT = "data";
036
037    /**
038     * The XMPP namespace of the In-Band Bytestream.
039     */
040    public static final String NAMESPACE = "http://jabber.org/protocol/ibb";
041
042    /* unique session ID identifying this In-Band Bytestream */
043    private final String sessionID;
044
045    /* sequence of this packet in regard to the other data packets */
046    private final long seq;
047
048    /* the data contained in this packet */
049    private final String data;
050
051    private byte[] decodedData;
052
053    /**
054     * Creates a new In-Band Bytestream data packet.
055     *
056     * @param sessionID unique session ID identifying this In-Band Bytestream
057     * @param seq sequence of this stanza in regard to the other data packets
058     * @param data the base64 encoded data contained in this packet
059     */
060    public DataPacketExtension(String sessionID, long seq, String data) {
061        if (sessionID == null || "".equals(sessionID)) {
062            throw new IllegalArgumentException("Session ID must not be null or empty");
063        }
064        if (seq < 0 || seq > 65535) {
065            throw new IllegalArgumentException("Sequence must not be between 0 and 65535");
066        }
067        if (data == null) {
068            throw new IllegalArgumentException("Data must not be null");
069        }
070        this.sessionID = sessionID;
071        this.seq = seq;
072        this.data = data;
073    }
074
075    /**
076     * Returns the unique session ID identifying this In-Band Bytestream.
077     *
078     * @return the unique session ID identifying this In-Band Bytestream
079     */
080    public String getSessionID() {
081        return sessionID;
082    }
083
084    /**
085     * Returns the sequence of this stanza in regard to the other data packets.
086     *
087     * @return the sequence of this stanza in regard to the other data packets.
088     */
089    public long getSeq() {
090        return seq;
091    }
092
093    /**
094     * Returns the data contained in this packet.
095     *
096     * @return the data contained in this packet.
097     */
098    public String getData() {
099        return data;
100    }
101
102    /**
103     * Returns the decoded data or null if data could not be decoded.
104     * <p>
105     * The encoded data is invalid if it contains bad Base64 input characters or
106     * if it contains the pad ('=') character on a position other than the last
107     * character(s) of the data. See <a
108     * href="http://xmpp.org/extensions/xep-0047.html#sec">XEP-0047</a> Section
109     * 6.
110     *
111     * @return the decoded data
112     */
113    public byte[] getDecodedData() {
114        // return cached decoded data
115        if (this.decodedData != null) {
116            return this.decodedData;
117        }
118
119        // data must not contain the pad (=) other than end of data
120        if (data.matches(".*={1,2}+.+")) {
121            return null;
122        }
123
124        // decodeBase64 will return null if bad characters are included
125        this.decodedData = Base64.decode(data);
126        return this.decodedData;
127    }
128
129    @Override
130    public String getElementName() {
131        return ELEMENT;
132    }
133
134    @Override
135    public String getNamespace() {
136        return NAMESPACE;
137    }
138
139    @Override
140    public XmlStringBuilder toXML(String enclosingNamespace) {
141        XmlStringBuilder xml = getIQChildElementBuilder(new IQChildElementXmlStringBuilder(this));
142        xml.closeElement(this);
143        return xml;
144    }
145
146    protected IQChildElementXmlStringBuilder getIQChildElementBuilder(IQChildElementXmlStringBuilder xml) {
147        xml.attribute("seq", Long.toString(seq));
148        xml.attribute("sid", sessionID);
149        xml.rightAngleBracket();
150        xml.append(data);
151        return xml;
152    }
153}