multicastrouter.java

基于Jabber协议的即时消息服务器

            // Remote server has a multicast service so send pending packets to the
            // multicast service
            for (Packet packet : packets) {
                Element addresses = getAddresses(packet);
                for (Iterator it=addresses.elementIterator("address");it.hasNext();) {
                    Element address = (Element) it.next();
                    String jid = address.attributeValue("jid");
                    if (!jid.contains("@"+domain)) {
                        if (Type.bcc.toString().equals(address.attributeValue("type"))) {
                            it.remove();
                        }
                        else {
                            address.addAttribute("delivered", "true");
                        }
                    }
                }
                // Set that the target of the packet is the multicast service
                packet.setTo(multicastService);
                // Send the packet to the remote entity
                packetRouter.route(packet);
            }
        }
        else {
            // Remote server does not have a multicast service so send pending packets
            // to each address
            for (Packet packet : packets) {
                Element addresses = getAddresses(packet);
                List<String> targets = new ArrayList<String>();

                for (Iterator it=addresses.elementIterator("address");it.hasNext();) {
                    Element address = (Element) it.next();
                    String jid = address.attributeValue("jid");
                    // Keep a list of the remote users that are going to receive the packet
                    if (jid.contains("@"+domain)) {
                        targets.add(jid);
                    }
                    // Set as delivered
                    address.addAttribute("delivered", "true");
                    // Remove bcc addresses
                    if (Type.bcc.toString().equals(address.attributeValue("type"))) {
                        it.remove();
                    }
                }

                // Send the packet to each remote user
                for (String jid : targets) {
                    packet.setTo(jid);
                    packetRouter.route(packet);
                }
            }
        }
    }

    public void receivedAnswer(IQ packet) {
        // Look for the root node being discovered
        String domain = packet.getFrom().toString();
        boolean isRoot = true;
        if (!nodes.containsKey(domain)) {
            domain = roots.get(domain);
            isRoot = false;
        }

        // Check if this is a disco#info response
        if ("http://jabber.org/protocol/disco#info"
                .equals(packet.getChildElement().getNamespaceURI())) {

            // Check if the node supports JEP-33
            boolean supports = false;
            for (Iterator it = packet.getChildElement().elementIterator("feature"); it.hasNext();) {
                if (NAMESPACE.equals(((Element)it.next()).attributeValue("var"))) {
                    supports = true;
                    break;
                }
            }

            if (supports) {
                // JEP-33 is supported by the entity
                Collection<String> items = nodes.remove(domain);
                for (String item : items) {
                    roots.remove(item);
                }
                String multicastService = packet.getFrom().toString();
                cache.put(domain, multicastService);
                sendToRemoteServer(domain, multicastService);
            }
            else {
                if (isRoot && IQ.Type.error != packet.getType()) {
                    // Discover node items with the hope that a sub-item supports JEP-33
                    IQ iq = new IQ(IQ.Type.get);
                    iq.setFrom(server.getServerInfo().getName());
                    iq.setTo(packet.getFrom());
                    iq.setChildElement("query", "http://jabber.org/protocol/disco#items");
                    // Send the disco#items request to the remote server or component. The reply will be
                    // processed by the IQResultListener (interface that this class implements)
                    iqRouter.addIQResultListener(iq.getID(), this);
                    iqRouter.route(iq);
                }
                else if (!isRoot) {
                    // Process the disco#info response of an item that does not support JEP-33
                    roots.remove(packet.getFrom().toString());
                    Collection<String> items = nodes.get(domain);
                    if (items != null) {
                        items.remove(packet.getFrom().toString());
                        if (items.isEmpty()) {
                            nodes.remove(domain);
                            cache.put(domain, "");
                            sendToRemoteServer(domain, "");
                        }
                    }
                }
                else {
                    // Root domain does not support disco#info
                    nodes.remove(domain);
                    cache.put(domain, "");
                    sendToRemoteServer(domain, "");
                }
            }

        }
        else {
            // This is a disco#items response
            Collection<Element> items = packet.getChildElement().elements("item");

            if (IQ.Type.error == packet.getType() || items.isEmpty()) {
                // Root domain does not support disco#items
                nodes.remove(domain);
                cache.put(domain, "");
                sendToRemoteServer(domain, "");
            }
            else {
                // Keep the list of items found in the requested domain
                List<String> jids = new ArrayList<String>();
                for (Element item : items) {
                    String jid = item.attributeValue("jid");
                    jids.add(jid);
                    // Add that this item was found for the following domain
                    roots.put(jid, domain);
                }
                nodes.put(domain, new CopyOnWriteArrayList<String>(jids));

                // Send disco#info to each discovered item
                for (Element item : items) {
                    // Discover if remote server supports JEP-33 (Extended Stanza Addressing)
                    IQ iq = new IQ(IQ.Type.get);
                    iq.setFrom(server.getServerInfo().getName());
                    iq.setTo(item.attributeValue("jid"));
                    Element child = iq.setChildElement("query", "http://jabber.org/protocol/disco#info");
                    if (item.attributeValue("node") != null) {
                        child.addAttribute("node", item.attributeValue("node"));
                    }
                    // Send the disco#info request to the discovered item. The reply will be
                    // processed by the IQResultListener (interface that this class implements)
                    iqRouter.addIQResultListener(iq.getID(), this);
                    iqRouter.route(iq);
                }
            }
        }
    }

    public Iterator<String> getFeatures() {
        ArrayList<String> features = new ArrayList<String>();
        features.add(NAMESPACE);
        return features.iterator();
    }

    public void initialize(XMPPServer server) {
        super.initialize(server);
        this.server = server;
        this.packetRouter = server.getPacketRouter();
        this.iqRouter = server.getIQRouter();
    }

    /**
     * Enumarion of the possible semantics of a particular address.
     */
    private enum Type {
        /**
         * These addressees should receive 'blind carbon copies' of the stanza. This means that
         * the server MUST remove these addresses before the stanza is delivered to anyone other
         * than the given bcc addressee or the multicast service of the bcc addressee.
         */
        bcc,
        /**
         * These addressees are the secondary recipients of the stanza.
         */
        cc,
        /**
         * This address type contains no actual address information. Instead, it means that the
         * receiver SHOULD NOT reply to the message. This is useful when broadcasting messages
         * to many receivers.
         */
        noreply,
        /**
         * This is the JID of a Multi-User Chat room to which responses should be sent. When a
         * user wants to reply to this stanza, the client SHOULD join this room first. Clients
         * SHOULD respect this request unless an explicit override occurs. There MAY be more than
         * one replyto or replyroom on a stanza, in which case the reply stanza MUST be routed
         * to all of the addresses.
         */
        replyroom,
        /**
         * This is the address to which all replies are requested to be sent. Clients SHOULD
         * respect this request unless an explicit override occurs. There MAY be more than one
         * replyto or replyroom on a stanza, in which case the reply stanza MUST be routed to all
         * of the addresses.
         */
        replyto,
        /**
         * These addressees are the primary recipients of the stanza.
         */
        to;
    }
}