XEP-0478: Stream Limits Advertisement: initial support

smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java

@@ -82,6 +82,7 @@
 import org.jivesoftware.smack.packet.ErrorIQ;
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.IQ;
+import org.jivesoftware.smack.packet.Limits;
 import org.jivesoftware.smack.packet.Mechanisms;
 import org.jivesoftware.smack.packet.Message;
 import org.jivesoftware.smack.packet.MessageBuilder;
@@ -1902,6 +1903,9 @@ protected final void parseFeatures(XmlPullParser parser) throws XmlPullParserExc
                 case Compress.Feature.ELEMENT:
                     streamFeature = PacketParserUtils.parseCompressionFeature(parser);
                     break;
+                case Limits.ELEMENT:
+                    streamFeature = PacketParserUtils.parseLimitsFeature(parser);
+                    break;
                 default:
                     ExtensionElementProvider<ExtensionElement> provider = ProviderManager.getStreamFeatureProvider(name, namespace);
                     if (provider != null) {

smack-core/src/main/java/org/jivesoftware/smack/packet/Limits.java

@@ -0,0 +1,90 @@
+/*
+ *
+ * Copyright © 2014-2026 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.packet;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.util.XmlStringBuilder;
+
+/**
+ * Limits feature.
+ * For any XMPP stream, there is an "initiating entity" (a client or server) and a "responding entity" that they are connecting to.
+ * The responding entity advertises its limits in the <code>&lt;stream:features/&gt;</code> element that it sends at the start of the stream.
+ * <a href="https://xmpp.org/extensions/xep-0478.html">XEP-0478: Stream Limits Advertisement</a>
+ */
+public class Limits implements ExtensionElement {
+    public static final String ELEMENT = "limits";
+    public static final String NAMESPACE = "urn:xmpp:stream-limits:0";
+    public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
+    /**
+     * The maximum size of any first-level stream elements (including stanzas),
+     * in bytes the announcing entity is willing to accept.
+     * Guidance on acceptable limits is provided in RFC 6120 section 13.12.
+     * If the responding entity is unable to determine its limits, this child can be absent.
+     * Element: <code>&lt;max-bytes/&gt;</code>. Type UnsignedInt.
+     */
+    public final int maxBytes;
+
+    /**
+     * The number of seconds without any traffic from the initiating entity after which
+     * the server may consider the stream idle, and either perform liveness checks
+     * (using e.g. Stream Management (XEP-0198) or XMPP Ping (XEP-0199)) or terminate the stream.
+     * Guidance on handling idle connections is provided in RFC 6120 section 4.6.
+     * If the responding entity is unable to determine its limits, this child can be absent.
+     * Element: <code>&lt;idle-seconds/&gt;</code>. Type UnsignedInt.
+     */
+    public final int idleSeconds;
+
+    public Limits(int maxBytes, int idleSeconds) {
+        this.maxBytes = maxBytes;
+        this.idleSeconds = idleSeconds;
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public String getNamespace() {
+        return NAMESPACE;
+    }
+
+    public int getMaxBytes() {
+        return maxBytes;
+    }
+
+    public int getIdleSeconds() {
+        return idleSeconds;
+    }
+
+    @Override
+    public XmlStringBuilder toXML(XmlEnvironment enclosingNamespace) {
+        XmlStringBuilder xml = new XmlStringBuilder(this);
+        xml.rightAngleBracket();
+        if (maxBytes != 0) {
+            xml.element("max-bytes", String.valueOf(maxBytes));
+        }
+        if (idleSeconds != 0) {
+            xml.element("idle-seconds", String.valueOf(idleSeconds));
+        }
+        xml.closeElement(this);
+        return xml;
+    }
+
+}

smack-core/src/main/java/org/jivesoftware/smack/util/PacketParserUtils.java

@@ -36,6 +36,7 @@
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.IqData;
+import org.jivesoftware.smack.packet.Limits;
 import org.jivesoftware.smack.packet.Message;
 import org.jivesoftware.smack.packet.MessageBuilder;
 import org.jivesoftware.smack.packet.Presence;
@@ -894,6 +895,57 @@ public static Session.Feature parseSessionFeature(XmlPullParser parser) throws X
         return new Session.Feature(optional);
     }
 
+
+    /**
+     * Parse the stream limits from XEP-0478: Stream Limits Advertisement.
+     *
+     * @param parser the XML parser, positioned at the start of the "limits" stanza.
+     * @return a collection of Stings with the mechanisms included in the mechanisms stanza.
+     * @throws IOException if an I/O error occurred.
+     * @throws XmlPullParserException if an error in the XML parser occurred.
+     */
+    public static Limits parseLimitsFeature(XmlPullParser parser)
+            throws XmlPullParserException, IOException {
+        ParserUtils.assertAtStartTag(parser);
+        final int initialDepth = parser.getDepth();
+        int maxBytes = 0;
+        int idleSeconds = 0;
+        outerloop: while (true) {
+            XmlPullParser.Event event = parser.next();
+            switch (event) {
+                case START_ELEMENT:
+                    String name = parser.getName();
+                    switch (name) {
+                        case "max-bytes":
+                            try {
+                                maxBytes = Integer.parseUnsignedInt(parser.nextText());
+                            } catch (NumberFormatException ignored) {
+                                // ignore
+                            }
+                            break;
+                        case "idle-seconds":
+                            try {
+                                idleSeconds = Integer.parseUnsignedInt(parser.nextText());
+                            } catch (NumberFormatException ignored) {
+                                // ignore
+                            }
+                            break;
+                    }
+                    break;
+                case END_ELEMENT:
+                    if (parser.getDepth() == initialDepth) {
+                        break outerloop;
+                    }
+                    break;
+                default:
+                    // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                    break;
+            }
+        }
+
+        return new Limits(maxBytes, idleSeconds);
+    }
+
     public static void addExtensionElement(StanzaBuilder<?> stanzaBuilder, XmlPullParser parser, XmlEnvironment outerXmlEnvironment, JxmppContext jxmppContext)
                     throws XmlPullParserException, IOException, SmackParsingException {
         ParserUtils.assertAtStartTag(parser);

smack-core/src/test/java/org/jivesoftware/smack/AbstractXMPPConnectionTest.java

@@ -0,0 +1,95 @@
+/*
+ *
+ * Copyright 2018-2026 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertEquals;
+import static java.util.Arrays.asList;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+
+import org.jivesoftware.smack.packet.Bind;
+import org.jivesoftware.smack.packet.Limits;
+import org.jivesoftware.smack.packet.Mechanisms;
+import org.jivesoftware.smack.packet.Session;
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.test.util.SmackTestSuite;
+import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import org.junit.Test;
+
+public class AbstractXMPPConnectionTest extends SmackTestSuite {
+    private final DummyConnection connection = new DummyConnection();
+
+    @Test
+    public void parseFeatures() throws XmlPullParserException, IOException, SmackParsingException {
+        String featureStr = "<features xmlns='http://etherx.jabber.org/streams'>" +
+                "<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>" +
+                "  <mechanism>OAUTHBEARER</mechanism>" +
+                "  <mechanism>SCRAM-SHA-1</mechanism>" +
+                "  <mechanism>PLAIN</mechanism>" +
+                "  <mechanism>SCRAM-SHA-1-PLUS</mechanism>" +
+                "</mechanisms>" +
+                "<sasl-channel-binding xmlns='urn:xmpp:sasl-cb:0'>" +
+                "  <channel-binding type='tls-exporter' />" +
+                "</sasl-channel-binding>" +
+                "<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>" +
+                "  <required />" +
+                "</bind>" +
+                "<session xmlns='urn:ietf:params:xml:ns:xmpp-session'>" +
+                "  <optional />" +
+                "</session>" +
+                "<limits xmlns='urn:xmpp:stream-limits:0'>" +
+                "  <max-bytes>262144</max-bytes>" +
+                "  <idle-seconds>840</idle-seconds>" +
+                "</limits>" +
+                "<register xmlns='urn:xmpp:invite' />" +
+                "<register xmlns='urn:xmpp:ibr-token:0' />" +
+                "<register xmlns='http://jabber.org/features/iq-register' />" +
+                "<ver xmlns='urn:xmpp:features:rosterver' />" +
+                "<sub xmlns='urn:xmpp:features:pre-approval' />" +
+                "<csi xmlns='urn:xmpp:csi:0' />" +
+                "<c hash='sha-1' node='http://prosody.im'" +
+                "  ver='uWfOTni5YjTtMRfYAjNKsj2GUXM=' xmlns='http://jabber.org/protocol/caps' />" +
+                "</features>";
+        InputStream input = new ByteArrayInputStream(featureStr.getBytes(StandardCharsets.UTF_8));
+        XmlPullParser parser = PacketParserUtils.getParserFor(input);
+        connection.parseFeatures(parser);
+
+        assertTrue(connection.hasFeature("mechanisms", "urn:ietf:params:xml:ns:xmpp-sasl"));
+        Mechanisms featMechanisms = connection.getFeature(Mechanisms.class);
+        assertEquals(asList("OAUTHBEARER", "SCRAM-SHA-1", "PLAIN", "SCRAM-SHA-1-PLUS"), featMechanisms.getMechanisms());
+
+        assertTrue(connection.hasFeature("bind", "urn:ietf:params:xml:ns:xmpp-bind"));
+        Bind.Feature featBind = connection.getFeature(Bind.Feature.class);
+        assertEquals(Bind.Feature.INSTANCE, featBind);
+
+        assertTrue(connection.hasFeature("session", "urn:ietf:params:xml:ns:xmpp-session"));
+        Session.Feature featSession = connection.getFeature(Session.Feature.class);
+        assertTrue(featSession.isOptional());
+
+        assertTrue(connection.hasFeature("limits", "urn:xmpp:stream-limits:0"));
+        Limits featLimits = connection.getFeature(Limits.class);
+        assertEquals(262144, featLimits.getMaxBytes());
+        assertEquals(840, featLimits.getIdleSeconds());
+    }
+}