add models for Error conditions

libs/annotation-processor/src/main/java/im/conversations/android/annotation/processor/XmlElementProcessor.java

@@ -1,6 +1,7 @@
 package im.conversations.android.annotation.processor;
 
 import com.google.auto.service.AutoService;
+import com.google.common.base.CaseFormat;
 import com.google.common.base.Objects;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
@@ -8,7 +9,6 @@ import im.conversations.android.annotation.XmlElement;
 import im.conversations.android.annotation.XmlPackage;
 import java.io.IOException;
 import java.io.PrintWriter;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.processing.AbstractProcessor;
@@ -88,8 +88,9 @@ public class XmlElementProcessor extends AbstractProcessor {
 
     private static Id of(final TypeElement typeElement) {
         final XmlElement xmlElement = typeElement.getAnnotation(XmlElement.class);
-        PackageElement packageElement = (PackageElement) typeElement.getEnclosingElement();
+        PackageElement packageElement = getPackageElement(typeElement);
-        XmlPackage xmlPackage = packageElement.getAnnotation(XmlPackage.class);
+        XmlPackage xmlPackage =
+                packageElement == null ? null : packageElement.getAnnotation(XmlPackage.class);
         if (xmlElement == null) {
             throw new IllegalStateException(
                     String.format(
@@ -112,13 +113,29 @@ public class XmlElementProcessor extends AbstractProcessor {
         }
         final String name;
         if (Strings.isNullOrEmpty(elementName)) {
-            name = typeElement.getSimpleName().toString().toLowerCase(Locale.ROOT);
+            name =
+                    CaseFormat.UPPER_CAMEL.to(
+                            CaseFormat.LOWER_HYPHEN, typeElement.getSimpleName().toString());
         } else {
             name = elementName;
         }
         return new Id(name, namespace);
     }
 
+    private static PackageElement getPackageElement(final TypeElement typeElement) {
+        final Element parent = typeElement.getEnclosingElement();
+        if (parent instanceof PackageElement) {
+            return (PackageElement) parent;
+        } else {
+            final Element nextParent = parent.getEnclosingElement();
+            if (nextParent instanceof PackageElement) {
+                return (PackageElement) nextParent;
+            } else {
+                return null;
+            }
+        }
+    }
+
     public static class Id {
         public final String name;
         public final String namespace;

src/main/java/eu/siacs/conversations/xml/Element.java

@@ -9,6 +9,7 @@ import eu.siacs.conversations.utils.XmlHelper;
 import eu.siacs.conversations.xmpp.InvalidJid;
 import eu.siacs.conversations.xmpp.Jid;
 import eu.siacs.conversations.xmpp.stanzas.MessagePacket;
+import im.conversations.android.xmpp.ExtensionFactory;
 import im.conversations.android.xmpp.model.Extension;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -89,6 +90,11 @@ public class Element {
                 Collections2.filter(this.children, clazz::isInstance), clazz::cast);
     }
 
+    public Collection<ExtensionFactory.Id> getExtensionIds() {
+        return Collections2.transform(
+                this.children, c -> new ExtensionFactory.Id(c.getName(), c.getNamespace()));
+    }
+
     public String findChildContent(String name) {
         Element element = findChild(name);
         return element == null ? null : element.getContent();

src/main/java/eu/siacs/conversations/xml/Namespace.java

@@ -80,4 +80,6 @@ public final class Namespace {
     public static final String UNIFIED_PUSH = "http://gultsch.de/xmpp/drafts/unified-push";
     public static final String JABBER_CLIENT = "jabber:client";
     public static final String FORWARD = "urn:xmpp:forward:0";
+
+    public static final String STANZAS = "urn:ietf:params:xml:ns:xmpp-stanzas";
 }

src/main/java/eu/siacs/conversations/xml/XmlElementReader.java

@@ -1,7 +1,6 @@
 package eu.siacs.conversations.xml;
 
 import com.google.common.io.ByteSource;
-
 import java.io.IOException;
 import java.io.InputStream;
 
@@ -11,10 +10,10 @@ public class XmlElementReader {
         return read(ByteSource.wrap(bytes).openStream());
     }
 
-    public static Element read(InputStream inputStream) throws IOException {
+    public static Element read(final InputStream inputStream) throws IOException {
-        final XmlReader xmlReader = new XmlReader();
+        try (final XmlReader xmlReader = new XmlReader()) {
-        xmlReader.setInputStream(inputStream);
+            xmlReader.setInputStream(inputStream);
-        return xmlReader.readElement(xmlReader.readTag());
+            return xmlReader.readElement(xmlReader.readTag());
+        }
     }
-
 }

src/main/java/im/conversations/android/xmpp/ExtensionFactory.java

@@ -1,5 +1,6 @@
 package im.conversations.android.xmpp;
 
+import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
 import eu.siacs.conversations.xml.Element;
 import im.conversations.android.xmpp.model.Extension;
@@ -61,5 +62,13 @@ public final class ExtensionFactory {
         public int hashCode() {
             return Objects.hashCode(name, namespace);
         }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(this)
+                    .add("name", name)
+                    .add("namespace", namespace)
+                    .toString();
+        }
     }
 }

src/main/java/im/conversations/android/xmpp/XmppConnection.java

@@ -60,12 +60,13 @@ import im.conversations.android.xmpp.manager.DiscoManager;
 import im.conversations.android.xmpp.model.StreamElement;
 import im.conversations.android.xmpp.model.csi.Active;
 import im.conversations.android.xmpp.model.csi.Inactive;
+import im.conversations.android.xmpp.model.ping.Ping;
 import im.conversations.android.xmpp.model.register.Register;
 import im.conversations.android.xmpp.model.sm.Ack;
 import im.conversations.android.xmpp.model.sm.Enable;
 import im.conversations.android.xmpp.model.sm.Request;
 import im.conversations.android.xmpp.model.sm.Resume;
-import im.conversations.android.xmpp.model.stanza.IQ;
+import im.conversations.android.xmpp.model.stanza.Iq;
 import im.conversations.android.xmpp.model.stanza.Message;
 import im.conversations.android.xmpp.model.stanza.Presence;
 import im.conversations.android.xmpp.model.stanza.Stanza;
@@ -120,7 +121,7 @@ public class XmppConnection implements Runnable {
 
     protected final Account account;
     private final SparseArray<Stanza> mStanzaQueue = new SparseArray<>();
-    private final Hashtable<String, Pair<IQ, Consumer<IQ>>> packetCallbacks = new Hashtable<>();
+    private final Hashtable<String, Pair<Iq, Consumer<Iq>>> packetCallbacks = new Hashtable<>();
     private final Context context;
     private Socket socket;
     private XmlReader tagReader;
@@ -147,7 +148,7 @@ public class XmppConnection implements Runnable {
     private final AtomicInteger mSmCatchupMessageCounter = new AtomicInteger(0);
     private int attempt = 0;
     private final Consumer<Presence> presencePacketConsumer;
-    private final Consumer<IQ> iqPacketConsumer;
+    private final Consumer<Iq> iqPacketConsumer;
     private final Consumer<Message> messagePacketConsumer;
     private final BiFunction<Jid, String, Boolean> messageAcknowledgeProcessor;
     private final Consumer<Jid> bindConsumer;
@@ -1088,16 +1089,16 @@ public class XmppConnection implements Runnable {
     }
 
     private void processIq(final Tag currentTag) throws IOException {
-        final IQ packet = processStanza(currentTag, IQ.class);
+        final Iq packet = processStanza(currentTag, Iq.class);
         if (InvalidJid.invalid(packet.getTo()) || InvalidJid.invalid(packet.getFrom())) {
             Log.e(
                     Config.LOGTAG,
                     "encountered invalid IQ from " + packet.getFrom() + " to " + packet.getTo());
             return;
         }
-        final Consumer<IQ> callback;
+        final Consumer<Iq> callback;
         synchronized (this.packetCallbacks) {
-            final Pair<IQ, Consumer<IQ>> packetCallbackDuple = packetCallbacks.get(packet.getId());
+            final Pair<Iq, Consumer<Iq>> packetCallbackDuple = packetCallbacks.get(packet.getId());
             if (packetCallbackDuple != null) {
                 // Packets to the server should have responses from the server
                 if (toServer(packetCallbackDuple.first)) {
@@ -1118,7 +1119,7 @@ public class XmppConnection implements Runnable {
                         Log.e(Config.LOGTAG, account.address + ": ignoring spoofed iq packet");
                     }
                 }
-            } else if (packet.getType() == IQ.Type.GET || packet.getType() == IQ.Type.SET) {
+            } else if (packet.getType() == Iq.Type.GET || packet.getType() == Iq.Type.SET) {
                 callback = this.iqPacketConsumer;
             } else {
                 callback = null;
@@ -1510,12 +1511,12 @@ public class XmppConnection implements Runnable {
             sendRegistryRequest();
             return;
         }
-        final IQ preAuthRequest = new IQ(IQ.Type.SET);
+        final Iq preAuthRequest = new Iq(Iq.Type.SET);
         preAuthRequest.addChild("preauth", Namespace.PARS).setAttribute("token", preAuth);
         sendUnmodifiedIqPacket(
                 preAuthRequest,
                 (response) -> {
-                    if (response.getType() == IQ.Type.RESULT) {
+                    if (response.getType() == Iq.Type.RESULT) {
                         sendRegistryRequest();
                     } else {
                         final String error = ""; // response.getErrorCondition();
@@ -1527,16 +1528,16 @@ public class XmppConnection implements Runnable {
     }
 
     private void sendRegistryRequest() {
-        final IQ retrieveRegistration = new IQ(IQ.Type.GET);
+        final Iq retrieveRegistration = new Iq(Iq.Type.GET);
         retrieveRegistration.addExtension(new Register());
         retrieveRegistration.setTo(account.address.getDomain());
         sendUnmodifiedIqPacket(
                 retrieveRegistration,
                 (packet) -> {
-                    if (packet.getType() == IQ.Type.TIMEOUT) {
+                    if (packet.getType() == Iq.Type.TIMEOUT) {
                         return;
                     }
-                    if (packet.getType() == IQ.Type.ERROR) {
+                    if (packet.getType() == Iq.Type.ERROR) {
                         throw new StateChangingError(ConnectionState.REGISTRATION_FAILED);
                     }
                     final Register query = packet.getExtension(Register.class);
@@ -1546,7 +1547,7 @@ public class XmppConnection implements Runnable {
                     if (query.hasChild("username") && (query.hasChild("password"))) {
                         final Credential credential =
                                 CredentialStore.getInstance(context).get(account);
-                        final IQ registrationRequest = new IQ(IQ.Type.SET);
+                        final Iq registrationRequest = new Iq(Iq.Type.SET);
                         final Element username =
                                 new Element("username")
                                         .setContent(account.address.getEscapedLocal());
@@ -1621,8 +1622,8 @@ public class XmppConnection implements Runnable {
                 true);
     }
 
-    private void handleRegistrationResponse(final IQ packet) {
+    private void handleRegistrationResponse(final Iq packet) {
-        if (packet.getType() == IQ.Type.RESULT) {
+        if (packet.getType() == Iq.Type.RESULT) {
             ConversationsDatabase.getInstance(context)
                     .accountDao()
                     .setPendingRegistration(account.id, false);
@@ -1687,16 +1688,16 @@ public class XmppConnection implements Runnable {
         } else {
             resource = this.createNewResource(IDs.tiny(account.randomSeed));
         }
-        final IQ iq = new IQ(IQ.Type.SET);
+        final Iq iq = new Iq(Iq.Type.SET);
         iq.addChild("bind", Namespace.BIND).addChild("resource").setContent(resource);
         this.sendUnmodifiedIqPacket(
                 iq,
                 (packet) -> {
-                    if (packet.getType() == IQ.Type.TIMEOUT) {
+                    if (packet.getType() == Iq.Type.TIMEOUT) {
                         return;
                     }
                     final Element bind = packet.findChild("bind");
-                    if (bind != null && packet.getType() == IQ.Type.RESULT) {
+                    if (bind != null && packet.getType() == Iq.Type.RESULT) {
                         isBound = true;
                         final String jid = bind.findChildContent("jid");
                         if (Strings.isNullOrEmpty(jid)) {
@@ -1740,7 +1741,7 @@ public class XmppConnection implements Runnable {
                                         + packet);
                     }
                     final Element error = packet.findChild("error");
-                    if (packet.getType() == IQ.Type.ERROR
+                    if (packet.getType() == Iq.Type.ERROR
                             && error != null
                             && error.hasChild("conflict")) {
                         final String alternativeResource = createNewResource(IDs.tiny());
@@ -1764,8 +1765,8 @@ public class XmppConnection implements Runnable {
     }
 
     private void clearIqCallbacks() {
-        final IQ failurePacket = new IQ(IQ.Type.TIMEOUT);
+        final Iq failurePacket = new Iq(Iq.Type.TIMEOUT);
-        final ArrayList<Consumer<IQ>> callbacks = new ArrayList<>();
+        final ArrayList<Consumer<Iq>> callbacks = new ArrayList<>();
         synchronized (this.packetCallbacks) {
             if (this.packetCallbacks.size() == 0) {
                 return;
@@ -1776,15 +1777,15 @@ public class XmppConnection implements Runnable {
                             + ": clearing "
                             + this.packetCallbacks.size()
                             + " iq callbacks");
-            final Iterator<Pair<IQ, Consumer<IQ>>> iterator =
+            final Iterator<Pair<Iq, Consumer<Iq>>> iterator =
                     this.packetCallbacks.values().iterator();
             while (iterator.hasNext()) {
-                Pair<IQ, Consumer<IQ>> entry = iterator.next();
+                Pair<Iq, Consumer<Iq>> entry = iterator.next();
                 callbacks.add(entry.second);
                 iterator.remove();
             }
         }
-        for (final Consumer<IQ> callback : callbacks) {
+        for (final Consumer<Iq> callback : callbacks) {
             try {
                 callback.accept(failurePacket);
             } catch (StateChangingError error) {
@@ -1807,15 +1808,15 @@ public class XmppConnection implements Runnable {
 
     private void sendStartSession() {
         Log.d(Config.LOGTAG, account.address + ": sending legacy session to outdated server");
-        final IQ startSession = new IQ(IQ.Type.SET);
+        final Iq startSession = new Iq(Iq.Type.SET);
         startSession.addChild("session", "urn:ietf:params:xml:ns:xmpp-session");
         this.sendUnmodifiedIqPacket(
                 startSession,
                 (packet) -> {
-                    if (packet.getType() == IQ.Type.RESULT) {
+                    if (packet.getType() == Iq.Type.RESULT) {
                         enableStreamManagement();
                         sendPostBindInitialization(false);
-                    } else if (packet.getType() != IQ.Type.TIMEOUT) {
+                    } else if (packet.getType() != Iq.Type.TIMEOUT) {
                         throw new StateChangingError(ConnectionState.SESSION_FAILURE);
                     }
                 },
@@ -2004,15 +2005,15 @@ public class XmppConnection implements Runnable {
         return String.format("%s.%s", context.getString(R.string.app_name), postfixId);
     }
 
-    public ListenableFuture<IQ> sendIqPacket(final IQ packet) {
+    public ListenableFuture<Iq> sendIqPacket(final Iq packet) {
-        final SettableFuture<IQ> future = SettableFuture.create();
+        final SettableFuture<Iq> future = SettableFuture.create();
         sendIqPacket(
                 packet,
                 result -> {
                     final var type = result.getType();
-                    if (type == IQ.Type.RESULT) {
+                    if (type == Iq.Type.RESULT) {
                         future.set(result);
-                    } else if (type == IQ.Type.TIMEOUT) {
+                    } else if (type == Iq.Type.TIMEOUT) {
                         future.setException(new TimeoutException());
                     } else {
                         // TODO some sort of IqErrorException
@@ -2022,13 +2023,13 @@ public class XmppConnection implements Runnable {
         return future;
     }
 
-    public String sendIqPacket(final IQ packet, final Consumer<IQ> callback) {
+    public String sendIqPacket(final Iq packet, final Consumer<Iq> callback) {
         packet.setFrom(account.address);
         return this.sendUnmodifiedIqPacket(packet, callback, false);
     }
 
     public synchronized String sendUnmodifiedIqPacket(
-            final IQ packet, final Consumer<IQ> callback, boolean force) {
+            final Iq packet, final Consumer<Iq> callback, boolean force) {
         if (Strings.isNullOrEmpty(packet.getId())) {
             packet.setId(IDs.medium());
         }
@@ -2106,9 +2107,9 @@ public class XmppConnection implements Runnable {
 
     public void sendPing() {
         if (!r()) {
-            final IQ iq = new IQ(IQ.Type.GET);
+            final Iq iq = new Iq(Iq.Type.GET);
             iq.setFrom(account.address);
-            iq.addChild("ping", Namespace.PING);
+            iq.addExtension(new Ping());
             this.sendIqPacket(iq, null);
         }
         this.lastPingSent = SystemClock.elapsedRealtime();

src/main/java/im/conversations/android/xmpp/manager/BlockingManager.java

@@ -7,7 +7,7 @@ import im.conversations.android.xmpp.model.blocking.Block;
 import im.conversations.android.xmpp.model.blocking.Blocklist;
 import im.conversations.android.xmpp.model.blocking.Item;
 import im.conversations.android.xmpp.model.blocking.Unblock;
-import im.conversations.android.xmpp.model.stanza.IQ;
+import im.conversations.android.xmpp.model.stanza.Iq;
 import java.util.Objects;
 
 public class BlockingManager extends AbstractManager {
@@ -38,13 +38,13 @@ public class BlockingManager extends AbstractManager {
     }
 
     public void fetch() {
-        final IQ iqPacket = new IQ(IQ.Type.GET);
+        final Iq iqPacket = new Iq(Iq.Type.GET);
         iqPacket.addChild(new Blocklist());
         connection.sendIqPacket(iqPacket, this::handleFetchResult);
     }
 
-    private void handleFetchResult(final IQ result) {
+    private void handleFetchResult(final Iq result) {
-        if (result.getType() != IQ.Type.RESULT) {
+        if (result.getType() != Iq.Type.RESULT) {
             return;
         }
         final var blocklist = result.getExtension(Blocklist.class);

src/main/java/im/conversations/android/xmpp/manager/CarbonsManager.java

@@ -5,7 +5,7 @@ import im.conversations.android.xmpp.XmppConnection;
 import im.conversations.android.xmpp.model.carbons.Enable;
 import im.conversations.android.xmpp.model.carbons.Received;
 import im.conversations.android.xmpp.model.carbons.Sent;
-import im.conversations.android.xmpp.model.stanza.IQ;
+import im.conversations.android.xmpp.model.stanza.Iq;
 import im.conversations.android.xmpp.processor.MessageProcessor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -24,12 +24,12 @@ public class CarbonsManager extends AbstractManager {
     }
 
     public void enable() {
-        final var iq = new IQ(IQ.Type.SET);
+        final var iq = new Iq(Iq.Type.SET);
         iq.addExtension(new Enable());
         connection.sendIqPacket(
                 iq,
                 result -> {
-                    if (result.getType() == IQ.Type.RESULT) {
+                    if (result.getType() == Iq.Type.RESULT) {
                         LOGGER.info("{}: successfully enabled carbons", getAccount().address);
                         this.enabled = true;
                     } else {

src/main/java/im/conversations/android/xmpp/manager/DiscoManager.java

@@ -17,7 +17,7 @@ import im.conversations.android.xmpp.XmppConnection;
 import im.conversations.android.xmpp.model.disco.info.InfoQuery;
 import im.conversations.android.xmpp.model.disco.items.Item;
 import im.conversations.android.xmpp.model.disco.items.ItemsQuery;
-import im.conversations.android.xmpp.model.stanza.IQ;
+import im.conversations.android.xmpp.model.stanza.Iq;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
@@ -52,7 +52,7 @@ public class DiscoManager extends AbstractManager {
             @Nullable final String node,
             @Nullable final EntityCapabilities.Hash hash) {
         final var requestNode = hash != null && node != null ? hash.capabilityNode(node) : node;
-        final var iqRequest = new IQ(IQ.Type.GET);
+        final var iqRequest = new Iq(Iq.Type.GET);
         iqRequest.setTo(entity.address);
         final InfoQuery infoQueryRequest = iqRequest.addExtension(new InfoQuery());
         if (requestNode != null) {
@@ -114,7 +114,7 @@ public class DiscoManager extends AbstractManager {
     public ListenableFuture<Collection<Item>> items(
             @NonNull final Entity.DiscoItem entity, @Nullable final String node) {
         final var requestNode = Strings.emptyToNull(node);
-        final var iqPacket = new IQ(IQ.Type.GET);
+        final var iqPacket = new Iq(Iq.Type.GET);
         iqPacket.setTo(entity.address);
         final ItemsQuery itemsQueryRequest = iqPacket.addExtension(new ItemsQuery());
         if (requestNode != null) {

src/main/java/im/conversations/android/xmpp/manager/RosterManager.java

@@ -6,7 +6,7 @@ import com.google.common.collect.Collections2;
 import im.conversations.android.xmpp.XmppConnection;
 import im.conversations.android.xmpp.model.roster.Item;
 import im.conversations.android.xmpp.model.roster.Query;
-import im.conversations.android.xmpp.model.stanza.IQ;
+import im.conversations.android.xmpp.model.stanza.Iq;
 import java.util.Objects;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -29,7 +29,7 @@ public class RosterManager extends AbstractManager {
         final var account = getAccount();
         final var database = getDatabase();
         final String rosterVersion = database.accountDao().getRosterVersion(account.id);
-        final IQ iqPacket = new IQ(IQ.Type.GET);
+        final Iq iqPacket = new Iq(Iq.Type.GET);
         final Query rosterQuery = new Query();
         iqPacket.addChild(rosterQuery);
         if (Strings.isNullOrEmpty(rosterVersion)) {
@@ -41,8 +41,8 @@ public class RosterManager extends AbstractManager {
         connection.sendIqPacket(iqPacket, this::handleFetchResult);
     }
 
-    private void handleFetchResult(final IQ result) {
+    private void handleFetchResult(final Iq result) {
-        if (result.getType() != IQ.Type.RESULT) {
+        if (result.getType() != Iq.Type.RESULT) {
             return;
         }
         final var query = result.getExtension(Query.class);

src/main/java/im/conversations/android/xmpp/model/error/Condition.java

@@ -0,0 +1,188 @@
+package im.conversations.android.xmpp.model.error;
+
+import eu.siacs.conversations.xml.Namespace;
+import im.conversations.android.annotation.XmlElement;
+import im.conversations.android.xmpp.model.Extension;
+
+public abstract class Condition extends Extension {
+
+    public Condition(Class<? extends Extension> clazz) {
+        super(clazz);
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class BadRequest extends Condition {
+
+        public BadRequest() {
+            super(BadRequest.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class Conflict extends Condition {
+
+        public Conflict() {
+            super(Conflict.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class FeatureNotImplemented extends Condition {
+
+        public FeatureNotImplemented() {
+            super(FeatureNotImplemented.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class Forbidden extends Condition {
+
+        public Forbidden() {
+            super(Forbidden.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class Gone extends Condition {
+
+        public Gone() {
+            super(Gone.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class InternalServerError extends Condition {
+
+        public InternalServerError() {
+            super(InternalServerError.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class ItemNotFound extends Condition {
+
+        public ItemNotFound() {
+            super(ItemNotFound.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class JidMalformed extends Condition {
+
+        public JidMalformed() {
+            super(JidMalformed.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class NotAcceptable extends Condition {
+
+        public NotAcceptable() {
+            super(NotAcceptable.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class NotAllowed extends Condition {
+
+        public NotAllowed() {
+            super(NotAllowed.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class NotAuthorized extends Condition {
+
+        public NotAuthorized() {
+            super(NotAuthorized.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class PaymentRequired extends Condition {
+
+        public PaymentRequired() {
+            super(PaymentRequired.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class RecipientUnavailable extends Condition {
+
+        public RecipientUnavailable() {
+            super(RecipientUnavailable.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class Redirect extends Condition {
+
+        public Redirect() {
+            super(Redirect.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class RegistrationRequired extends Condition {
+
+        public RegistrationRequired() {
+            super(RegistrationRequired.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class RemoteServerNotFound extends Condition {
+
+        public RemoteServerNotFound() {
+            super(RemoteServerNotFound.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class RemoteServerTimeout extends Condition {
+
+        public RemoteServerTimeout() {
+            super(RemoteServerTimeout.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class ResourceConstraint extends Condition {
+
+        public ResourceConstraint() {
+            super(ResourceConstraint.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class ServiceUnavailable extends Condition {
+
+        public ServiceUnavailable() {
+            super(ServiceUnavailable.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class SubscriptionRequired extends Condition {
+
+        public SubscriptionRequired() {
+            super(SubscriptionRequired.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class UndefinedCondition extends Condition {
+
+        public UndefinedCondition() {
+            super(UndefinedCondition.class);
+        }
+    }
+
+    @XmlElement(namespace = Namespace.STANZAS)
+    public static class UnexpectedRequest extends Condition {
+
+        public UnexpectedRequest() {
+            super(UnexpectedRequest.class);
+        }
+    }
+}

src/main/java/im/conversations/android/xmpp/model/error/Error.java

@@ -0,0 +1,21 @@
+package im.conversations.android.xmpp.model.error;
+
+import eu.siacs.conversations.xml.Namespace;
+import im.conversations.android.annotation.XmlElement;
+import im.conversations.android.xmpp.model.Extension;
+
+@XmlElement(namespace = Namespace.JABBER_CLIENT)
+public class Error extends Extension {
+
+    public Error() {
+        super(Error.class);
+    }
+
+    public Condition getCondition() {
+        return this.getExtension(Condition.class);
+    }
+
+    public void setCondition(final Condition condition) {
+        this.addExtension(condition);
+    }
+}

src/main/java/im/conversations/android/xmpp/model/ping/Ping.java

@@ -0,0 +1,13 @@
+package im.conversations.android.xmpp.model.ping;
+
+import eu.siacs.conversations.xml.Namespace;
+import im.conversations.android.annotation.XmlElement;
+import im.conversations.android.xmpp.model.Extension;
+
+@XmlElement(namespace = Namespace.PING)
+public class Ping extends Extension {
+
+    public Ping() {
+        super(Ping.class);
+    }
+}

src/main/java/im/conversations/android/xmpp/model/stanza/Iq.java

@@ -5,14 +5,14 @@ import im.conversations.android.annotation.XmlElement;
 import java.util.Locale;
 
 @XmlElement
-public class IQ extends Stanza {
+public class Iq extends Stanza {
 
-    public IQ() {
+    public Iq() {
-        super(IQ.class);
+        super(Iq.class);
     }
 
-    public IQ(final Type type) {
+    public Iq(final Type type) {
-        super(IQ.class);
+        super(Iq.class);
         this.setAttribute("type", type.toString().toLowerCase(Locale.ROOT));
     }
 

src/main/java/im/conversations/android/xmpp/model/stanza/Stanza.java

@@ -3,6 +3,7 @@ package im.conversations.android.xmpp.model.stanza;
 import eu.siacs.conversations.xmpp.Jid;
 import im.conversations.android.xmpp.model.Extension;
 import im.conversations.android.xmpp.model.StreamElement;
+import im.conversations.android.xmpp.model.error.Error;
 
 public abstract class Stanza extends StreamElement {
 
@@ -33,4 +34,8 @@ public abstract class Stanza extends StreamElement {
     public void setTo(final Jid to) {
         this.setAttribute("to", to);
     }
+
+    public Error getError() {
+        return this.getExtension(Error.class);
+    }
 }

src/main/java/im/conversations/android/xmpp/processor/BindProcessor.java

@@ -9,7 +9,6 @@ import im.conversations.android.xmpp.manager.BlockingManager;
 import im.conversations.android.xmpp.manager.BookmarkManager;
 import im.conversations.android.xmpp.manager.DiscoManager;
 import im.conversations.android.xmpp.manager.RosterManager;
-import im.conversations.android.xmpp.model.stanza.Presence;
 import java.util.function.Consumer;
 
 public class BindProcessor extends XmppConnection.Delegate implements Consumer<Jid> {
@@ -47,7 +46,7 @@ public class BindProcessor extends XmppConnection.Delegate implements Consumer<J
 
         getManager(BookmarkManager.class).fetch();
 
-        connection.sendPresencePacket(new Presence());
+        // connection.sendPresencePacket(new Presence());
 
         // TODO send initial presence
     }

src/main/java/im/conversations/android/xmpp/processor/IqProcessor.java

@@ -5,41 +5,83 @@ import com.google.common.base.Preconditions;
 import im.conversations.android.xmpp.XmppConnection;
 import im.conversations.android.xmpp.manager.BlockingManager;
 import im.conversations.android.xmpp.manager.RosterManager;
+import im.conversations.android.xmpp.model.Extension;
 import im.conversations.android.xmpp.model.blocking.Block;
 import im.conversations.android.xmpp.model.blocking.Unblock;
+import im.conversations.android.xmpp.model.error.Condition;
+import im.conversations.android.xmpp.model.error.Error;
+import im.conversations.android.xmpp.model.ping.Ping;
 import im.conversations.android.xmpp.model.roster.Query;
-import im.conversations.android.xmpp.model.stanza.IQ;
+import im.conversations.android.xmpp.model.stanza.Iq;
 import java.util.Arrays;
 import java.util.function.Consumer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-public class IqProcessor extends XmppConnection.Delegate implements Consumer<IQ> {
+public class IqProcessor extends XmppConnection.Delegate implements Consumer<Iq> {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(IqProcessor.class);
 
     public IqProcessor(final Context context, final XmppConnection connection) {
         super(context, connection);
     }
 
     @Override
-    public void accept(final IQ packet) {
+    public void accept(final Iq packet) {
-        final IQ.Type type = packet.getType();
+        final Iq.Type type = packet.getType();
-        Preconditions.checkArgument(Arrays.asList(IQ.Type.GET, IQ.Type.SET).contains(type));
+        Preconditions.checkArgument(Arrays.asList(Iq.Type.GET, Iq.Type.SET).contains(type));
-        if (type == IQ.Type.SET
+        if (type == Iq.Type.SET
                 && connection.fromAccount(packet)
                 && packet.hasExtension(Query.class)) {
             getManager(RosterManager.class).handlePush(packet.getExtension(Query.class));
+            sendResultFor(packet);
             return;
         }
-        if (type == IQ.Type.SET
+        if (type == Iq.Type.SET
                 && connection.fromAccount(packet)
                 && packet.hasExtension(Block.class)) {
             getManager(BlockingManager.class).handlePush(packet.getExtension(Block.class));
+            sendResultFor(packet);
             return;
         }
-        if (type == IQ.Type.SET
+        if (type == Iq.Type.SET
                 && connection.fromAccount(packet)
                 && packet.hasExtension(Unblock.class)) {
             getManager(BlockingManager.class).handlePush(packet.getExtension(Unblock.class));
+            sendResultFor(packet);
             return;
         }
-        // TODO return feature not implemented
+        if (type == Iq.Type.GET && packet.hasExtension(Ping.class)) {
+            LOGGER.debug("Responding to ping from {}", packet.getFrom());
+            sendResultFor(packet);
+            return;
+        }
+
+        final var extensionIds = packet.getExtensionIds();
+        LOGGER.info("Could not handle {}. Sending feature-not-implemented", extensionIds);
+        sendErrorFor(packet, new Condition.FeatureNotImplemented());
+    }
+
+    public void sendResultFor(final Iq request, final Extension... extensions) {
+        final var from = request.getFrom();
+        final var id = request.getId();
+        final var response = new Iq(Iq.Type.RESULT);
+        response.setTo(from);
+        response.setId(id);
+        for (final Extension extension : extensions) {
+            response.addExtension(extension);
+        }
+        connection.sendIqPacket(response);
+    }
+
+    public void sendErrorFor(final Iq request, final Condition condition) {
+        final var from = request.getFrom();
+        final var id = request.getId();
+        final var response = new Iq(Iq.Type.ERROR);
+        response.setTo(from);
+        response.setId(id);
+        final Error error = response.addExtension(new Error());
+        error.setCondition(condition);
+        connection.sendIqPacket(response);
     }
 }

src/main/java/im/conversations/android/xmpp/processor/MessageProcessor.java

@@ -42,5 +42,14 @@ public class MessageProcessor extends XmppConnection.Delegate implements Consume
         if (!Strings.isNullOrEmpty(body)) {
             LOGGER.info("'{}' from {}", body, message.getFrom());
         }
+
+        // TODO process receipt requests (184 + 333)
+
+        // TODO collect Extensions that require transformation (everything that will end up in the
+        // message tables)
+
+        // TODO pass pubsub events to pubsub manager
+
+        // TODO pass JMI to JingleManager
     }
 }

src/test/java/im/conversations/android/xmpp/XmlElementReaderTest.java

@@ -6,8 +6,11 @@ import static org.junit.Assert.assertEquals;
 
 import eu.siacs.conversations.xml.Element;
 import eu.siacs.conversations.xml.XmlElementReader;
+import im.conversations.android.xmpp.model.error.Condition;
+import im.conversations.android.xmpp.model.error.Error;
 import im.conversations.android.xmpp.model.roster.Item;
 import im.conversations.android.xmpp.model.roster.Query;
+import im.conversations.android.xmpp.model.stanza.Message;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.Collection;
@@ -31,4 +34,23 @@ public class XmlElementReaderTest {
         final Collection<Item> items = query.getExtensions(Item.class);
         assertEquals(2, items.size());
     }
+
+    public void readMessageError() throws IOException {
+        final String xml =
+                "<message\n"
+                        + "    to='juliet@capulet.com/balcony'\n"
+                        + "    from='romeo@montague.net/garden'\n"
+                        + "    xmlns='jabber:client'\n"
+                        + "    type='error'>\n"
+                        + "  <body>Wherefore art thou, Romeo?</body>\n"
+                        + "  <error code='404' type='cancel'>\n"
+                        + "    <item-not-found xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>\n"
+                        + "  </error>\n"
+                        + "</message>";
+        final Element element = XmlElementReader.read(xml.getBytes(StandardCharsets.UTF_8));
+        assertThat(element, instanceOf(Message.class));
+        final Message message = (Message) element;
+        final Error error = message.getError();
+        assertThat(error.getCondition(), instanceOf(Condition.ItemNotFound.class));
+    }
 }