Merge branch '1.5'

10 files changed, 247 insertions, 126 deletions

diff --git a/src/base/QXmppMessage.cpp b/src/base/QXmppMessage.cpp
index c0923d22..9527f5ed 100644
--- a/src/base/QXmppMessage.cpp
+++ b/src/base/QXmppMessage.cpp
@@ -1659,7 +1659,7 @@ void QXmppMessage::serializeExtensions(QXmlStreamWriter *writer, QXmpp::SceMode
             writer->writeStartElement(QStringLiteral("encryption"));
             writer->writeDefaultNamespace(ns_eme);
             writer->writeAttribute(QStringLiteral("namespace"), d->encryptionMethod);
-            helperToXmlAddAttribute(writer, QStringLiteral("name"), d->encryptionName);
+            helperToXmlAddAttribute(writer, QStringLiteral("name"), encryptionName());
             writer->writeEndElement();
         }
 
diff --git a/src/base/QXmppStream.cpp b/src/base/QXmppStream.cpp
index 0ea87cbd..7c49c762 100644
--- a/src/base/QXmppStream.cpp
+++ b/src/base/QXmppStream.cpp
@@ -197,7 +197,7 @@ QXmppTask<QXmpp::SendResult> QXmppStream::send(QXmppPacket &&packet, bool &writt
 ///
 /// \since QXmpp 1.5
 ///
-QXmppTask<QXmppStream::IqResult> QXmppStream::sendIq(QXmppIq &&iq)
+QXmppTask<QXmppStream::IqResult> QXmppStream::sendIq(QXmppIq &&iq, const QString &to)
 {
     using namespace QXmpp;
 
@@ -212,7 +212,7 @@ QXmppTask<QXmppStream::IqResult> QXmppStream::sendIq(QXmppIq &&iq)
         iq.setId(QXmppUtils::generateStanzaUuid());
     }
 
-    return sendIq(QXmppPacket(iq), iq.id(), iq.to());
+    return sendIq(QXmppPacket(iq), iq.id(), to);
 }
 
 ///
@@ -466,10 +466,18 @@ bool QXmppStream::handleIqResponse(const QDomElement &stanza)
         return false;
     }
 
-    if (auto itr = d->runningIqs.find(stanza.attribute(QStringLiteral("id")));
+    const auto id = stanza.attribute(QStringLiteral("id"));
+    if (auto itr = d->runningIqs.find(id);
         itr != d->runningIqs.end()) {
-        if (stanza.attribute("from") != itr.value().jid) {
-            warning(QStringLiteral("Received IQ response to one of our requests from wrong sender. Ignoring."));
+        const auto expectedFrom = itr.value().jid;
+        // Check that the sender of the response matches the recipient of the request.
+        // Stanzas coming from the server on behalf of the user's account must have no "from"
+        // attribute or have it set to the user's bare JID.
+        // If 'from' is empty, the IQ has been sent by the server. In this case we don't need to
+        // do the check as we trust the server anyways.
+        if (const auto from = stanza.attribute("from"); !from.isEmpty() && from != expectedFrom) {
+            warning(QStringLiteral("Ignored received IQ response to request '%1' because of wrong sender '%2' instead of expected sender '%3'")
+                        .arg(id, from, expectedFrom));
             return false;
         }
 
diff --git a/src/base/QXmppStream.h b/src/base/QXmppStream.h
index 55dc7967..a7584366 100644
--- a/src/base/QXmppStream.h
+++ b/src/base/QXmppStream.h
@@ -47,7 +47,7 @@ public:
     QXmppTask<QXmpp::SendResult> send(QXmppPacket &&);
 
     using IqResult = std::variant<QDomElement, QXmppError>;
-    QXmppTask<IqResult> sendIq(QXmppIq &&);
+    QXmppTask<IqResult> sendIq(QXmppIq &&, const QString &to);
     QXmppTask<IqResult> sendIq(QXmppPacket &&, const QString &id, const QString &to);
     void cancelOngoingIqs();
     bool hasIqId(const QString &id) const;
diff --git a/src/client/QXmppCarbonManagerV2.cpp b/src/client/QXmppCarbonManagerV2.cpp
index 7959cab3..97831731 100644
--- a/src/client/QXmppCarbonManagerV2.cpp
+++ b/src/client/QXmppCarbonManagerV2.cpp
@@ -18,10 +18,9 @@ using namespace QXmpp::Private;
 class CarbonEnableIq : public QXmppIq
 {
 public:
-    CarbonEnableIq(const QString &jid)
+    CarbonEnableIq()
         : QXmppIq()
     {
-        setTo(jid);
         setType(QXmppIq::Set);
     }
 
@@ -165,7 +164,7 @@ void QXmppCarbonManagerV2::enableCarbons()
         return;
     }
 
-    client()->sendIq(CarbonEnableIq(client()->configuration().jidBare())).then(this, [this](QXmppClient::IqResult domResult) {
+    client()->sendIq(CarbonEnableIq()).then(this, [this](QXmppClient::IqResult domResult) {
         if (auto err = parseIq(std::move(domResult))) {
             warning("Could not enable message carbons: " % err->description);
         } else {
diff --git a/src/client/QXmppIqHandling.h b/src/client/QXmppIqHandling.h
index 7535bc30..63eba306 100644
--- a/src/client/QXmppIqHandling.h
+++ b/src/client/QXmppIqHandling.h
@@ -95,12 +95,10 @@ namespace Private {
             iq.parse(element);
             iq.setE2eeMetadata(e2eeMetadata);
 
-            processHandleIqResult(
-                client,
-                iq.id(),
-                iq.from(),
-                e2eeMetadata,
-                invokeIqHandler(std::forward<Handler>(handler), std::move(iq)));
+            auto id = iq.id(), from = iq.from();
+
+            processHandleIqResult(client, id, from, e2eeMetadata,
+                                  invokeIqHandler(std::forward<Handler>(handler), std::move(iq)));
             return true;
         }
         return false;
diff --git a/src/client/QXmppMamManager.cpp b/src/client/QXmppMamManager.cpp
index c39a3411..fe0735c7 100644
--- a/src/client/QXmppMamManager.cpp
+++ b/src/client/QXmppMamManager.cpp
@@ -9,29 +9,98 @@
 #include "QXmppConstants_p.h"
 #include "QXmppDataForm.h"
 #include "QXmppE2eeExtension.h"
-#include "QXmppFutureUtils_p.h"
 #include "QXmppMamIq.h"
 #include "QXmppMessage.h"
+#include "QXmppPromise.h"
 #include "QXmppUtils.h"
 
 #include <unordered_map>
 
 #include <QDomElement>
 
+using namespace QXmpp;
 using namespace QXmpp::Private;
 
+template<typename T, typename Converter>
+auto transform(const T &input, Converter convert)
+{
+    using Output = std::decay_t<decltype(convert(*input.begin()))>;
+    QVector<Output> output;
+    output.reserve(input.size());
+    std::transform(input.begin(), input.end(), std::back_inserter(output), std::move(convert));
+    return output;
+}
+
+template<typename T>
+auto sum(const T &c)
+{
+    return std::accumulate(c.begin(), c.end(), 0);
+}
+
+struct MamMessage
+{
+    QDomElement element;
+    std::optional<QDateTime> delay;
+};
+
+enum EncryptedType { Unencrypted,
+                     Encrypted };
+
+QXmppMessage parseMamMessage(const MamMessage &mamMessage, EncryptedType encrypted)
+{
+    QXmppMessage m;
+    m.parse(mamMessage.element, encrypted == Encrypted ? ScePublic : SceAll);
+    if (mamMessage.delay) {
+        m.setStamp(*mamMessage.delay);
+    }
+    return m;
+}
+
+std::optional<std::tuple<MamMessage, QString>> parseMamMessageResult(const QDomElement &messageEl)
+{
+    auto resultElement = messageEl.firstChildElement("result");
+    if (resultElement.isNull() || resultElement.namespaceURI() != ns_mam) {
+        return {};
+    }
+
+    auto forwardedElement = resultElement.firstChildElement("forwarded");
+    if (forwardedElement.isNull() || forwardedElement.namespaceURI() != ns_forwarding) {
+        return {};
+    }
+
+    auto queryId = resultElement.attribute("queryid");
+
+    auto messageElement = forwardedElement.firstChildElement("message");
+    if (messageElement.isNull()) {
+        return {};
+    }
+
+    auto parseDelay = [](const auto &forwardedEl) -> std::optional<QDateTime> {
+        auto delayEl = forwardedEl.firstChildElement("delay");
+        if (!delayEl.isNull() && delayEl.namespaceURI() == ns_delayed_delivery) {
+            return QXmppUtils::datetimeFromString(delayEl.attribute("stamp"));
+        }
+        return {};
+    };
+
+    return { { MamMessage { messageElement, parseDelay(forwardedElement) }, queryId } };
+}
+
 struct RetrieveRequestState
 {
     QXmppPromise<QXmppMamManager::RetrieveResult> promise;
     QXmppMamResultIq iq;
-    QVector<QXmppMessage> messages;
+    QVector<MamMessage> messages;
+    QVector<QXmppMessage> processedMessages;
+    uint runningDecryptionJobs = 0;
 
     void finish()
     {
+        Q_ASSERT(messages.count() == processedMessages.count());
         promise.finish(
             QXmppMamManager::RetrievedMessages {
                 std::move(iq),
-                std::move(messages) });
+                std::move(processedMessages) });
     }
 };
 
@@ -87,28 +156,8 @@ QStringList QXmppMamManager::discoveryFeatures() const
 bool QXmppMamManager::handleStanza(const QDomElement &element)
 {
     if (element.tagName() == "message") {
-        QDomElement resultElement = element.firstChildElement("result");
-        if (!resultElement.isNull() && resultElement.namespaceURI() == ns_mam) {
-            QDomElement forwardedElement = resultElement.firstChildElement("forwarded");
-            QString queryId = resultElement.attribute("queryid");
-
-            if (forwardedElement.isNull() || forwardedElement.namespaceURI() != ns_forwarding) {
-                return false;
-            }
-
-            auto messageElement = forwardedElement.firstChildElement("message");
-            auto delayElement = forwardedElement.firstChildElement("delay");
-
-            if (messageElement.isNull()) {
-                return false;
-            }
-
-            QXmppMessage message;
-            message.parse(messageElement);
-            if (!delayElement.isNull() && delayElement.namespaceURI() == ns_delayed_delivery) {
-                const QString stamp = delayElement.attribute("stamp");
-                message.setStamp(QXmppUtils::datetimeFromString(stamp));
-            }
+        if (auto result = parseMamMessageResult(element)) {
+            auto &[message, queryId] = *result;
 
             auto itr = d->ongoingRequests.find(queryId.toStdString());
             if (itr != d->ongoingRequests.end()) {
@@ -116,7 +165,7 @@ bool QXmppMamManager::handleStanza(const QDomElement &element)
                 itr->second.messages.append(std::move(message));
             } else {
                 // signal-based API
-                Q_EMIT archivedMessageReceived(queryId, message);
+                Q_EMIT archivedMessageReceived(queryId, parseMamMessage(message, Unencrypted));
             }
             return true;
         }
@@ -240,74 +289,97 @@ QString QXmppMamManager::retrieveArchivedMessages(const QString &to,
 QXmppTask<QXmppMamManager::RetrieveResult> QXmppMamManager::retrieveMessages(const QString &to, const QString &node, const QString &jid, const QDateTime &start, const QDateTime &end, const QXmppResultSetQuery &resultSetQuery)
 {
     auto queryIq = buildRequest(to, node, jid, start, end, resultSetQuery);
+    auto queryId = queryIq.queryId();
+
+    auto [itr, inserted] = d->ongoingRequests.insert({ queryIq.queryId().toStdString(), RetrieveRequestState() });
+    Q_ASSERT(inserted);
 
-    auto [itr, _] = d->ongoingRequests.insert({ queryIq.queryId().toStdString(), RetrieveRequestState() });
+    // create task here; promise could finish immediately after client()->sendIq()
+    auto task = itr->second.promise.task();
 
     // retrieve messages
-    client()->sendIq(std::move(queryIq)).then(this, [this, queryId = queryIq.queryId()](QXmppClient::IqResult result) {
+    client()->sendIq(std::move(queryIq)).then(this, [this, queryId](QXmppClient::IqResult result) {
         auto itr = d->ongoingRequests.find(queryId.toStdString());
         if (itr == d->ongoingRequests.end()) {
             return;
         }
+        auto &state = itr->second;
 
-        if (std::holds_alternative<QDomElement>(result)) {
-            auto &iq = itr->second.iq;
-            iq.parse(std::get<QDomElement>(result));
+        // handle IQ sending errors
+        if (std::holds_alternative<QXmppError>(result)) {
+            state.promise.finish(std::get<QXmppError>(result));
+            d->ongoingRequests.erase(itr);
+            return;
+        }
 
-            if (iq.type() == QXmppIq::Error) {
-                itr->second.promise.finish(QXmppError { iq.error().text(), iq.error() });
-                d->ongoingRequests.erase(itr);
-                return;
-            }
+        // parse IQ
+        auto &iq = state.iq;
+        iq.parse(std::get<QDomElement>(result));
 
-            // decrypt encrypted messages
-            if (auto *e2eeExt = client()->encryptionExtension()) {
-                auto &messages = itr->second.messages;
-                auto running = std::make_shared<uint>(0);
-                // handle case when no message is encrypted
-                auto hasEncryptedMessages = false;
+        // handle MAM error result IQ
+        if (iq.type() == QXmppIq::Error) {
+            state.promise.finish(QXmppError { iq.error().text(), iq.error() });
+            d->ongoingRequests.erase(itr);
+            return;
+        }
 
-                for (auto i = 0; i < messages.size(); i++) {
-                    if (!e2eeExt->isEncrypted(messages.at(i))) {
-                        continue;
-                    }
-                    hasEncryptedMessages = true;
-
-                    auto message = messages.at(i);
-                    (*running)++;
-                    e2eeExt->decryptMessage(std::move(message)).then(this, [this, i, running, queryId](auto result) {
-                        (*running)--;
-                        auto itr = d->ongoingRequests.find(queryId.toStdString());
-                        if (itr == d->ongoingRequests.end()) {
-                            return;
-                        }
-
-                        if (std::holds_alternative<QXmppMessage>(result)) {
-                            itr->second.messages[i] = std::get<QXmppMessage>(std::move(result));
-                        } else {
-                            warning(QStringLiteral("Error decrypting message."));
-                        }
-                        if (*running == 0) {
-                            itr->second.finish();
-                            d->ongoingRequests.erase(itr);
-                        }
-                    });
+        // decrypt encrypted messages
+        if (auto *e2eeExt = client()->encryptionExtension()) {
+            // initialize processed messages (we need random access because
+            // decryptMessage() may finish in random order)
+            state.processedMessages.resize(state.messages.size());
+
+            // check for encrypted messages (once)
+            auto messagesEncrypted = transform(state.messages, [&](const auto &m) {
+                return e2eeExt->isEncrypted(m.element);
+            });
+            auto encryptedCount = sum(messagesEncrypted);
+
+            // We can't do this on the fly (with ++ and --) in the for loop
+            // because some decryptMessage() jobs could finish instantly
+            state.runningDecryptionJobs = encryptedCount;
+
+            for (auto i = 0; i < state.messages.size(); i++) {
+                if (!messagesEncrypted[i]) {
+                    continue;
                 }
 
-                if (!hasEncryptedMessages) {
-                    // finish here, no decryptMessage callback will do it
-                    itr->second.finish();
-                    d->ongoingRequests.erase(itr);
-                }
-            } else {
-                itr->second.finish();
-                d->ongoingRequests.erase(itr);
+                e2eeExt->decryptMessage(parseMamMessage(state.messages.at(i), Encrypted)).then(this, [this, i, queryId](auto result) {
+                    auto itr = d->ongoingRequests.find(queryId.toStdString());
+                    Q_ASSERT(itr != d->ongoingRequests.end());
+
+                    auto &state = itr->second;
+
+                    // store decrypted message, fallback to encrypted message
+                    if (std::holds_alternative<QXmppMessage>(result)) {
+                        state.processedMessages[i] = std::get<QXmppMessage>(std::move(result));
+                    } else {
+                        warning(QStringLiteral("Error decrypting message."));
+                        state.processedMessages[i] = parseMamMessage(state.messages[i], Unencrypted);
+                    }
+
+                    // finish promise if this was the last job
+                    state.runningDecryptionJobs--;
+                    if (state.runningDecryptionJobs == 0) {
+                        state.finish();
+                        d->ongoingRequests.erase(itr);
+                    }
+                });
+            }
+
+            // finishing the promise is done after decryptMessage()
+            if (encryptedCount > 0) {
+                return;
             }
-        } else {
-            itr->second.promise.finish(std::get<QXmppError>(result));
-            d->ongoingRequests.erase(itr);
         }
+
+        // for the case without decryption, finish here
+        state.processedMessages = transform(state.messages, [](const auto &m) {
+            return parseMamMessage(m, Unencrypted);
+        });
+        state.finish();
+        d->ongoingRequests.erase(itr);
     });
 
-    return itr->second.promise.task();
+    return task;
 }
diff --git a/src/client/QXmppOutgoingClient.cpp b/src/client/QXmppOutgoingClient.cpp
index 046bdcf2..19895938 100644
--- a/src/client/QXmppOutgoingClient.cpp
+++ b/src/client/QXmppOutgoingClient.cpp
@@ -324,11 +324,9 @@ bool QXmppOutgoingClient::isStreamResumed() const
 ///
 QXmppTask<QXmppStream::IqResult> QXmppOutgoingClient::sendIq(QXmppIq &&iq)
 {
-    // always set a to address (the QXmppStream needs this for matching)
-    if (iq.to().isEmpty()) {
-        iq.setTo(d->config.domain());
-    }
-    return QXmppStream::sendIq(std::move(iq));
+    // If 'to' is empty the user's bare JID is meant implicitly (see RFC6120, section 10.3.3.).
+    auto to = iq.to();
+    return QXmppStream::sendIq(std::move(iq), to.isEmpty() ? d->config.jidBare() : to);
 }
 
 void QXmppOutgoingClient::_q_socketDisconnected()
diff --git a/src/omemo/QXmppOmemoManager.cpp b/src/omemo/QXmppOmemoManager.cpp
index 0aab152d..a3ad12bb 100644
--- a/src/omemo/QXmppOmemoManager.cpp
+++ b/src/omemo/QXmppOmemoManager.cpp
@@ -340,7 +340,7 @@ QXmppOmemoManager::~QXmppOmemoManager() = default;
 ///
 /// This should be called after starting the client and before the login.
 /// It must only be called after \c setUp() has been called once for the user
-/// during one of the past login session.
+/// during one of the past login sessions.
 /// It does not need to be called if setUp() has been called during the current
 /// login session.
 ///
@@ -1267,29 +1267,33 @@ bool Manager::handlePubSubEvent(const QDomElement &element, const QString &pubSu
         switch (event.eventType()) {
         // Items have been published.
         case QXmppPubSubEventBase::Items: {
-            const auto items = event.items();
-
             // Only process items if the event notification contains one.
-            // That is necessary because PubSub allows publishing without
-            // items leading to notification-only events.
-            if (!items.isEmpty()) {
-                const auto &deviceListItem = items.constFirst();
-                if (deviceListItem.id() == QXmppPubSubManager::standardItemIdToString(QXmppPubSubManager::Current)) {
-                    d->updateDevices(pubSubService, event.items().constFirst());
+            // That is necessary because PubSub allows publishing without items leading to
+            // notification-only events.
+            if (const auto &items = event.items(); !items.isEmpty()) {
+                // Since the usage of the item ID \c QXmppPubSubManager::Current is only RECOMMENDED
+                // by \xep{0060, Publish-Subscribe} (PubSub) but not obligatory, an appropriate
+                // contact device list is determined.
+                // In case of the own device list node, it is sctrictly processed as a recommended
+                // singleton item and changed to fit that if needed.
+                const auto isOwnDeviceListNode = d->ownBareJid() == pubSubService;
+                if (isOwnDeviceListNode) {
+                    const auto &deviceListItem = items.constFirst();
+                    if (deviceListItem.id() == QXmppPubSubManager::standardItemIdToString(QXmppPubSubManager::Current)) {
+                        d->updateDevices(pubSubService, event.items().constFirst());
+                    } else {
+                        d->handleIrregularDeviceListChanges(pubSubService);
+                    }
                 } else {
-                    d->handleIrregularDeviceListChanges(pubSubService);
+                    d->updateContactDevices(pubSubService, items);
                 }
             }
 
             break;
         }
-        // Items have been retracted.
+        // Specific items are deleted.
         case QXmppPubSubEventBase::Retract: {
-            // Specific items are deleted.
-            const auto &retractedItem = event.retractIds().constFirst();
-            if (retractedItem == QXmppPubSubManager::standardItemIdToString(QXmppPubSubManager::Current)) {
-                d->handleIrregularDeviceListChanges(pubSubService);
-            }
+            d->handleIrregularDeviceListChanges(pubSubService);
         }
         // All items are deleted.
         case QXmppPubSubEventBase::Purge:
diff --git a/src/omemo/QXmppOmemoManager_p.cpp b/src/omemo/QXmppOmemoManager_p.cpp
index 1c86d80b..bcfd8303 100644
--- a/src/omemo/QXmppOmemoManager_p.cpp
+++ b/src/omemo/QXmppOmemoManager_p.cpp
@@ -920,7 +920,7 @@ bool ManagerPrivate::updatePreKeyPairs(uint32_t count)
         deviceBundle.addPublicPreKey(preKeyId, serializedPublicPreKey);
     }
 
-    this->preKeyPairs.insert(serializedPreKeyPairs);
+    preKeyPairs.insert(serializedPreKeyPairs);
     omemoStorage->addPreKeyPairs(serializedPreKeyPairs);
     ownDevice.latestPreKeyId = latestPreKeyId - 1 + count;
 
@@ -2648,6 +2648,36 @@ void ManagerPrivate::updateOwnDevicesLocally(bool isDeviceListNodeExistent, Func
 }
 
 //
+// Updates all locally stored devices of a contact.
+//
+// \param deviceOwnerJid bare JID of the devices' owner
+// \param deviceListItems PEP items that may contain a device list
+//
+// \returns a found device list item
+//
+std::optional<QXmppOmemoDeviceListItem> QXmppOmemoManagerPrivate::updateContactDevices(const QString &deviceOwnerJid, const QVector<QXmppOmemoDeviceListItem> &deviceListItems)
+{
+    if (deviceListItems.size() > 1) {
+        const auto itr = std::find_if(deviceListItems.cbegin(), deviceListItems.cend(), [=](const QXmppOmemoDeviceListItem &item) {
+            return item.id() == QXmppPubSubManager::Current;
+        });
+
+        if (itr != deviceListItems.cend()) {
+            updateDevices(deviceOwnerJid, *itr);
+            return *itr;
+        } else {
+            warning("Device list for JID '" % deviceOwnerJid % "' could not be updated because the node contains more than one item but none with the singleton node's specific ID '" % QXmppPubSubManager::standardItemIdToString(QXmppPubSubManager::Current) % "'");
+            handleIrregularDeviceListChanges(deviceOwnerJid);
+            return {};
+        }
+    }
+
+    const auto &item = deviceListItems.constFirst();
+    updateDevices(deviceOwnerJid, item);
+    return item;
+}
+
+//
 // Updates all locally stored devices by a passed device list item.
 //
 // \param deviceOwnerJid bare JID of the devices' owner
@@ -2783,7 +2813,7 @@ void ManagerPrivate::updateDevices(const QString &deviceOwnerJid, const QXmppOme
     // Publish an own correct device list if the PEP service's one is incorrect
     // and the devices are already set up locally.
     if (isOwnDeviceListIncorrect) {
-        if (!this->devices.isEmpty()) {
+        if (!devices.isEmpty()) {
             publishDeviceListItem(true, [=](bool isPublished) {
                 if (!isPublished) {
                     warning("Own device list item could not be published in order to correct the PEP service's one");
@@ -2795,7 +2825,7 @@ void ManagerPrivate::updateDevices(const QString &deviceOwnerJid, const QXmppOme
 
 //
 // Corrects the own device list on the PEP service by the locally stored
-// devices or set a contact device to be removed locally in the future.
+// devices or sets a contact device to be removed locally in the future.
 //
 // \param deviceOwnerJid bare JID of the devices' owner
 //
@@ -2810,7 +2840,7 @@ void ManagerPrivate::handleIrregularDeviceListChanges(const QString &deviceOwner
         auto future = pubSubManager->deleteOwnPepNode(ns_omemo_2_devices);
         future.then(q, [=](QXmppPubSubManager::Result result) {
             if (const auto error = std::get_if<QXmppError>(&result)) {
-                warning("Node '" % QString(ns_omemo_2_devices) % "'  of JID '" % deviceOwnerJid %
+                warning("Node '" % QString(ns_omemo_2_devices) % "' of JID '" % deviceOwnerJid %
                         "' could not be deleted in order to recover from an inconsistent node: " %
                         errorToString(*error));
             } else {
@@ -2845,7 +2875,7 @@ void ManagerPrivate::handleIrregularDeviceListChanges(const QString &deviceOwner
             }
         });
     } else {
-        auto &ownerDevices = this->devices[deviceOwnerJid];
+        auto &ownerDevices = devices[deviceOwnerJid];
 
         // Set a timestamp for locally stored contact devices being removed
         // later if their device list item is removed, if their device list node
@@ -3055,16 +3085,27 @@ QXmppTask<bool> ManagerPrivate::changeDeviceLabel(const QString &deviceLabel)
 //
 QXmppTask<QXmppPubSubManager::ItemResult<QXmppOmemoDeviceListItem>> ManagerPrivate::requestDeviceList(const QString &jid)
 {
-    auto future = pubSubManager->requestItem<QXmppOmemoDeviceListItem>(jid, ns_omemo_2_devices, QXmppPubSubManager::Current);
-    future.then(q, [this, jid](QXmppPubSubManager::ItemResult<QXmppOmemoDeviceListItem> result) mutable {
+    QXmppPromise<QXmppPubSubManager::ItemResult<QXmppOmemoDeviceListItem>> interface;
+
+    // Since the usage of the item ID \c QXmppPubSubManager::Current is only RECOMMENDED by
+    // \xep{0060, Publish-Subscribe} (PubSub) but not obligatory, all items are requested even if
+    // the node should contain only one item.
+    auto future = pubSubManager->requestItems<QXmppOmemoDeviceListItem>(jid, ns_omemo_2_devices);
+    future.then(q, [this, interface, jid](QXmppPubSubManager::ItemsResult<QXmppOmemoDeviceListItem> result) mutable {
         if (const auto error = std::get_if<QXmppError>(&result)) {
             warning("Device list for JID '" % jid % "' could not be retrieved: " % errorToString(*error));
+            interface.finish(*error);
+        } else if (const auto &items = std::get<QXmppPubSubManager::Items<QXmppOmemoDeviceListItem>>(result).items; items.isEmpty()) {
+            const auto errorMessage = "Device list for JID '" % jid % "' could not be retrieved because the node does not contain any item";
+            warning(errorMessage);
+            interface.finish(QXmppError { errorMessage });
+        } else if (const auto item = updateContactDevices(jid, items); item) {
+            interface.finish(*item);
         } else {
-            const auto &item = std::get<QXmppOmemoDeviceListItem>(result);
-            updateDevices(jid, item);
+            interface.finish(QXmppError { "Device list for JID '" % jid % "' could not be retrieved because the node does not contain an appropriate item" });
         }
     });
-    return future;
+    return interface.task();
 }
 
 //
diff --git a/src/omemo/QXmppOmemoManager_p.h b/src/omemo/QXmppOmemoManager_p.h
index 96f10f94..0792bdf2 100644
--- a/src/omemo/QXmppOmemoManager_p.h
+++ b/src/omemo/QXmppOmemoManager_p.h
@@ -290,6 +290,7 @@ public:
     QXmppOmemoDeviceListItem deviceListItem(bool addOwnDevice = true);
     template<typename Function>
     void updateOwnDevicesLocally(bool isDeviceListNodeExistent, Function continuation);
+    std::optional<QXmppOmemoDeviceListItem> updateContactDevices(const QString &deviceOwnerJid, const QVector<QXmppOmemoDeviceListItem> &deviceListItems);
     void updateDevices(const QString &deviceOwnerJid, const QXmppOmemoDeviceListItem &deviceListItem);
     void handleIrregularDeviceListChanges(const QString &deviceOwnerJid);
     template<typename Function>