lib-jitsi-meet/modules/xmpp/Caps.js

/* global $, b64_sha1, Strophe */
import XMPPEvents from "../../service/xmpp/XMPPEvents";
import Listenable from "../util/Listenable";

/**
 * The property
 */
const IDENTITY_PROPERTIES = ["category", "type", "lang", "name"];
const IDENTITY_PROPERTIES_FOR_COMPARE = ["category", "type", "lang"];
const HASH = "sha-1";

function compareIdentities(a, b) {
    let res = 0;
    IDENTITY_PROPERTIES_FOR_COMPARE.some(key =>
        (res = ((a[key] > b[key]) && 1) || ((a[key] < b[key]) && -1)) !== 0
    );
    return res;
}

/**
 * Implements xep-0115 ( http://xmpp.org/extensions/xep-0115.html )
 */
export default class Caps extends Listenable {
    /**
     * Constructs new Caps instance.
     * @param {Strophe.Connection} connection the strophe connection object
     * @param {String} node the value of the node attribute of the "c" xml node
     * that will be sent to the other participants
     */
    constructor(connection = {}, node = "http://jitsi.org/jitsimeet") {
        super();
        this.node = node;
        this.disco = connection.disco;
        if(!this.disco) {
            throw new Error(
                "Missing strophe-plugins "
                + "(disco and caps plugins are required)!");
        }

        this.versionToCapabilities = Object.create(null);
        this.jidToVersion = Object.create(null);
        this.version = "";
        this.rooms = new Set();

        const emuc = connection.emuc;
        emuc.addListener(XMPPEvents.EMUC_ROOM_ADDED,
            room => this._addChatRoom(room));
        emuc.addListener(XMPPEvents.EMUC_ROOM_REMOVED,
            room => this._removeChatRoom(room));
        for(let jid in emuc.rooms) {
            this._addChatRoom(this.emuc.rooms[jid]);
        }

        Strophe.addNamespace("CAPS", "http://jabber.org/protocol/caps");
        this.disco.addFeature(Strophe.NS.CAPS);
        connection.addHandler(this._handleCaps.bind(this), Strophe.NS.CAPS);

        this._onMucMemberLeft = this._removeJidToVersionEntry.bind(this);
    }

    /**
     * Adds new feature to the list of supported features for the local
     * participant
     * @param {String} feature the name of the feature.
     * @param {boolean} submit if true - new presence with updated "c" node
     * will be sent.
     */
    addFeature(feature, submit = false) {
        this.disco.addFeature(feature);
        this._generateVersion();
        if(submit) {
            this.submit();
        }
    }

    /**
     * Removes a feature from the list of supported features for the local
     * participant
     * @param {String} feature the name of the feature.
     * @param {boolean} submit if true - new presence with updated "c" node
     * will be sent.
     */
    removeFeature(feature, submit = false) {
        this.disco.removeFeature(feature);
        this._generateVersion();
        if(submit) {
            this.submit();
        }
    }

    /**
     * Sends new presence stanza for every room from the list of rooms.
     */
    submit() {
        this.rooms.forEach(room => room.sendPresence());
    }

    /**
     * Returns a set with the features for a participant.
     * @param {String} jid the jid of the participant
     * @param {int} timeout the timeout in ms for reply from the participant.
     * @returns {Promise<Set<String>, Error>}
     */
    getFeatures(jid, timeout = 5000) {
        let user
            = (jid in this.jidToVersion) ? this.jidToVersion[jid] : null;
        if(!user || !(user.version in this.versionToCapabilities))
        {
            const node = (user)? user.node + "#" + user.version : null;
            return new Promise ( (resolve, reject) =>
                this.disco.info(jid, node, response => {
                        const features = new Set();
                        $(response).find(">query>feature").each((idx, el) =>
                            features.add(el.getAttribute("var")));
                        if(user) {
                            this.versionToCapabilities[user.version]
                                = features;
                        }
                        resolve(features);
                    }, reject , timeout)
            );
        }
        return Promise.resolve(this.versionToCapabilities[user.version]);
    }

    /**
     * Adds ChatRoom instance to the list of rooms. Adds listeners to the room
     * and adds "c" element to the presences of the room.
     * @param {ChatRoom} room the room.
     */
    _addChatRoom(room) {
        this.rooms.add(room);
        room.addListener(XMPPEvents.MUC_MEMBER_LEFT, this._onMucMemberLeft);
        this._fixChatRoomPresenceMap(room);
    }

    /**
     * Removes ChatRoom instance from the list of rooms. Removes listeners
     * added from the Caps class.
     * @param {ChatRoom} room the room.
     */
    _removeChatRoom(room) {
        this.rooms.delete(room);
        room.removeListener(XMPPEvents.MUC_MEMBER_LEFT, this._onMucMemberLeft);
    }

    /**
     * Creates/updates the "c" xml node into the presence of the passed room.
     * @param {ChatRoom} room the room.
     */
    _fixChatRoomPresenceMap(room) {
        room.addToPresence("c", {
            attributes: {
                xmlns: Strophe.NS.CAPS,
                hash: HASH,
                node: this.node,
                ver: this.version
            }
        });
    }

    /**
     * Handles this.version changes.
     */
    _notifyVersionChanged() {
        //update the version for all rooms
        this.rooms.forEach(room => this._fixChatRoomPresenceMap(room));
        this.submit();
    }

    /**
     * Generates the value for the "ver" attribute.
     */
    _generateVersion() {
        const identities = this.disco._identities.sort(compareIdentities);
        const features = this.disco._features.sort();
        this.version = b64_sha1(
            identities.reduce(
                (accumulatedValue, identity) => {
                    return IDENTITY_PROPERTIES.reduce((tmp, key, idx) => {
                        return (idx === 0 ? "" : "/") + identity[key];
                    }, "") + "<";
                }, ""
            ) + features.reduce((tmp, feature) => feature + "<", "")
        );
        this._notifyVersionChanged();
    }

    /**
     * Parses the "c" xml node from presence.
     * @param {DOMElement} stanza the presence packet
     */
    _handleCaps(stanza) {
        const from = stanza.getAttribute("from");
        const caps = stanza.querySelector("c");
        const version = caps.getAttribute("ver");
        const node = caps.getAttribute("node");
        const oldVersion = this.jidToVersion[from];
        this.jidToVersion[from] = {version, node};
        if(oldVersion && oldVersion.version !== version) {
            this.eventEmitter.emit(XMPPEvents.PARTCIPANT_FEATURES_CHANGED,
                from);
        }
        // return true to not remove the handler from Strophe
        return true;
    }

    /**
     * Removes entry from this.jidToVersion map.
     * @param {String} jid the jid to be removed.
     */
    _removeJidToVersionEntry(jid) {
        if(jid in this.jidToVersion) {
            delete this.jidToVersion[jid];
        }
    }
}