2020-06-19 01:42:03 +02:00
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/**
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*
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* Copyright 2020 Aditya Borikar.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jivesoftware.smack.altconnections;
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import java.io.FileNotFoundException;
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import java.io.IOException;
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import java.io.InputStream;
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import java.net.URI;
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import java.net.URISyntaxException;
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import java.net.URL;
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import java.net.URLConnection;
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import java.util.ArrayList;
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import java.util.List;
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import org.jivesoftware.smack.util.PacketParserUtils;
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2020-07-24 03:00:53 +02:00
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import org.jivesoftware.smack.util.ParserUtils;
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2020-06-19 01:42:03 +02:00
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import org.jivesoftware.smack.xml.XmlPullParser;
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import org.jivesoftware.smack.xml.XmlPullParserException;
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import org.jxmpp.jid.DomainBareJid;
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/**
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* The HTTP lookup method uses web host metadata to list the URIs of alternative connection methods.
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*
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* <p>In order to obtain host-meta XRD element from the host in the form of an <i>InputStream</i>,
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* use {@link #getXrdStream(DomainBareJid)} method. To obtain endpoints for Bosh or Websocket
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* connection endpoints from host, use {@link LinkRelation#BOSH} and {@link LinkRelation#WEBSOCKET}
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* respectively with the {@link #lookup(DomainBareJid, LinkRelation)} method. In case one is looking
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* for endpoints described by other than BOSH or Websocket LinkRelation, use the more flexible
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* {@link #lookup(DomainBareJid, String)} method.</p>
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* Example:<br>
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* <pre>
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* {@code
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* DomainBareJid xmppServerAddress = JidCreate.domainBareFrom("example.org");
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* List<URI> endpoints = HttpLookupMethod.lookup(xmppServiceAddress, LinkRelation.WEBSOCKET);
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* }
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* </pre>
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* @see <a href="https://xmpp.org/extensions/xep-0156.html#http">
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* HTTP Lookup Method from XEP-0156.
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* </a>
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*/
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public final class HttpLookupMethod {
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private static final String XRD_NAMESPACE = "http://docs.oasis-open.org/ns/xri/xrd-1.0";
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/**
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* Specifies a link relation for the selected type of connection.
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*/
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public enum LinkRelation {
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/**
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* Selects link relation attribute as "urn:xmpp:alt-connections:xbosh".
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*/
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BOSH("urn:xmpp:alt-connections:xbosh"),
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/**
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* Selects link relation attribute as "urn:xmpp:alt-connections:websocket".
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*/
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WEBSOCKET("urn:xmpp:alt-connections:websocket");
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private final String attribute;
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LinkRelation(String relAttribute) {
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this.attribute = relAttribute;
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}
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}
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/**
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* Get remote endpoints for the given LinkRelation from host.
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*
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* @param xmppServiceAddress address of host
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* @param relation LinkRelation as a string specifying type of connection
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* @return list of endpoints
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* @throws IOException exception due to input/output operations
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* @throws XmlPullParserException exception encountered during XML parsing
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* @throws URISyntaxException exception to indicate that a string could not be parsed as a URI reference
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*/
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public static List<URI> lookup(DomainBareJid xmppServiceAddress, String relation) throws IOException, XmlPullParserException, URISyntaxException {
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try (InputStream inputStream = getXrdStream(xmppServiceAddress)) {
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XmlPullParser xmlPullParser = PacketParserUtils.getParserFor(inputStream);
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List<URI> endpoints = parseXrdLinkReferencesFor(xmlPullParser, relation);
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return endpoints;
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}
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}
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/**
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* Get remote endpoints for the given LinkRelation from host.
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*
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* @param xmppServiceAddress address of host
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* @param relation {@link LinkRelation} specifying type of connection
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* @return list of endpoints
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* @throws IOException exception due to input/output operations
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* @throws XmlPullParserException exception encountered during XML parsing
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* @throws URISyntaxException exception to indicate that a string could not be parsed as a URI reference
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*/
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public static List<URI> lookup(DomainBareJid xmppServiceAddress, LinkRelation relation) throws IOException, XmlPullParserException, URISyntaxException {
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return lookup(xmppServiceAddress, relation.attribute);
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}
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/**
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* Constructs a HTTP connection with the host specified by the DomainBareJid
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* and retrieves XRD element in the form of an InputStream. The method will
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* throw a {@link FileNotFoundException} if host-meta isn't published.
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*
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* @param xmppServiceAddress address of host
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* @return InputStream containing XRD element
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* @throws IOException exception due to input/output operations
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*/
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public static InputStream getXrdStream(DomainBareJid xmppServiceAddress) throws IOException {
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final String metadataUrl = "https://" + xmppServiceAddress + "/.well-known/host-meta";
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final URL putUrl = new URL(metadataUrl);
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final URLConnection urlConnection = putUrl.openConnection();
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return urlConnection.getInputStream();
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}
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/**
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* Get remote endpoints for the provided LinkRelation from provided XmlPullParser.
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*
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* @param parser XmlPullParser that contains LinkRelations
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* @param relation type of endpoints specified by the given LinkRelation
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* @return list of endpoints
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* @throws IOException exception due to input/output operations
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* @throws XmlPullParserException exception encountered during XML parsing
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* @throws URISyntaxException exception to indicate that a string could not be parsed as a URI reference
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*/
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public static List<URI> parseXrdLinkReferencesFor(XmlPullParser parser, String relation) throws IOException, XmlPullParserException, URISyntaxException {
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2020-07-24 03:00:53 +02:00
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ParserUtils.forwardToStartElement(parser);
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2020-06-19 01:42:03 +02:00
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List<URI> uriList = new ArrayList<>();
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int initialDepth = parser.getDepth();
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loop: while (true) {
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XmlPullParser.TagEvent tag = parser.nextTag();
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switch (tag) {
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case START_ELEMENT:
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String name = parser.getName();
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String namespace = parser.getNamespace();
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String rel = parser.getAttributeValue("rel");
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if (!namespace.equals(XRD_NAMESPACE) || !name.equals("Link") || !rel.equals(relation)) {
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continue loop;
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}
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String endpointUri = parser.getAttributeValue("href");
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URI uri = new URI(endpointUri);
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uriList.add(uri);
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break;
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case END_ELEMENT:
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if (parser.getDepth() == initialDepth) {
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break loop;
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}
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break;
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}
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}
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return uriList;
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}
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/**
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* Get remote endpoints for the provided LinkRelation from provided XmlPullParser.
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*
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* @param parser XmlPullParser that contains LinkRelations
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* @param relation type of endpoints specified by the given LinkRelation
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* @return list of endpoints
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* @throws IOException exception due to input/output operations
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* @throws XmlPullParserException exception encountered during XML parsing
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* @throws URISyntaxException exception to indicate that a string could not be parsed as a URI reference
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*/
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public static List<URI> parseXrdLinkReferencesFor(XmlPullParser parser, LinkRelation relation) throws IOException, XmlPullParserException, URISyntaxException {
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return parseXrdLinkReferencesFor(parser, relation.attribute);
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}
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}
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