Add MessageHandler interface

src/CMakeLists.txt

@@ -102,6 +102,7 @@ set(INSTALL_HEADER_FILES
     client/QXmppEntityTimeManager.h
     client/QXmppInvokable.h
     client/QXmppMamManager.h
+    client/QXmppMessageHandler.h
     client/QXmppMessageReceiptManager.h
     client/QXmppMucManager.h
     client/QXmppOutgoingClient.h

src/client/QXmppClient.cpp

@@ -14,6 +14,7 @@
 #include "QXmppFutureUtils_p.h"
 #include "QXmppLogger.h"
 #include "QXmppMessage.h"
+#include "QXmppMessageHandler.h"
 #include "QXmppOutgoingClient.h"
 #include "QXmppPacket_p.h"
 #include "QXmppRosterManager.h"
@@ -126,6 +127,32 @@ bool process(const QList<QXmppClientExtension *> &extensions, const QDomElement
 
 }
 
+namespace QXmpp::Private::MessagePipeline {
+
+bool process(QXmppClient *client, const QList<QXmppClientExtension *> &extensions, QXmppMessage &&message)
+{
+    for (auto *extension : extensions) {
+        if (auto *messageHandler = dynamic_cast<QXmppMessageHandler *>(extension)) {
+            if (messageHandler->handleMessage(message)) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+bool process(QXmppClient *client, const QList<QXmppClientExtension *> &extensions, const QDomElement &element)
+{
+    if (element.tagName() != "message") {
+        return false;
+    }
+    QXmppMessage message;
+    message.parse(element);
+    return process(client, extensions, std::move(message));
+}
+
+}
+
 ///
 /// \typedef QXmppClient::IqResult
 ///
@@ -807,14 +834,28 @@ void QXmppClient::injectIq(const QDomElement &element, const std::optional<QXmpp
     }
 }
 
+///
+/// Processes the message with message handlers and emits messageReceived as a fallback.
+///
+bool QXmppClient::injectMessage(QXmppMessage &&message)
+{
+    auto handled = MessagePipeline::process(this, d->extensions, std::move(message));
+    if (!handled) {
+        // no extension handled the message
+        emit messageReceived(message);
+    }
+    return handled;
+}
+
 ///
 /// Give extensions a chance to handle incoming stanzas.
 ///
 void QXmppClient::_q_elementReceived(const QDomElement &element, bool &handled)
 {
     // The stanza comes directly from the XMPP stream, so it's not end-to-end
     // encrypted and there's no e2ee metadata (std::nullopt).
-    handled = StanzaPipeline::process(d->extensions, element, std::nullopt);
+    handled = StanzaPipeline::process(d->extensions, element, std::nullopt) ||
+        MessagePipeline::process(this, d->extensions, element);
 }
 
 void QXmppClient::_q_reconnect()

src/client/QXmppClient.h

@@ -309,6 +309,7 @@ public Q_SLOTS:
 
 private:
     void injectIq(const QDomElement &element, const std::optional<QXmppE2eeMetadata> &e2eeMetadata);
+    bool injectMessage(QXmppMessage &&message);
 
 private Q_SLOTS:
     void _q_elementReceived(const QDomElement &element, bool &handled);

src/client/QXmppClientExtension.cpp

@@ -119,3 +119,16 @@ void QXmppClientExtension::injectIq(const QDomElement &element, const std::optio
 {
     client()->injectIq(element, e2eeMetadata);
 }
+
+///
+/// Injects a message stanza into the client.
+///
+/// The stanza is processed by the client with all extensions implementing
+/// MessageHandler.
+///
+/// \since QXmpp 1.5
+///
+bool QXmppClientExtension::injectMessage(QXmppMessage &&message)
+{
+    return client()->injectMessage(std::move(message));
+}

src/client/QXmppClientExtension.h

@@ -13,6 +13,7 @@ class QDomElement;
 
 class QXmppClient;
 class QXmppClientExtensionPrivate;
+class QXmppMessage;
 class QXmppStream;
 
 ///
@@ -45,6 +46,7 @@ class QXMPP_EXPORT QXmppClientExtension : public QXmppLoggable, public QXmppExte
     virtual void setClient(QXmppClient *client);
 
     void injectIq(const QDomElement &element, const std::optional<QXmppE2eeMetadata> &e2eeMetadata);
+    bool injectMessage(QXmppMessage &&message);
 
 private:
     QXmppClientExtensionPrivate *const d;

src/client/QXmppMessageHandler.cpp

@@ -0,0 +1,19 @@
+// SPDX-FileCopyrightText: 2022 Linus Jahn <[email protected]>
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+///
+/// \class QXmppMessageHandler
+///
+/// Interface for handling messages.
+///
+/// \since QXmpp 1.5
+///
+
+///
+/// \fn QXmppMessageHandler::handleMessage()
+///
+/// Handles the message.
+///
+/// \returns Whether the message has been handled and no other extensions should process it.
+///

src/client/QXmppMessageHandler.h

@@ -0,0 +1,21 @@
+// SPDX-FileCopyrightText: 2022 Linus Jahn <[email protected]>
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#ifndef QXMPPMESSAGEHANDLER_H
+#define QXMPPMESSAGEHANDLER_H
+
+#include "QXmppExtension.h"
+#include "QXmppMessage.h"
+
+#include <variant>
+
+#include <QFuture>
+
+class QXMPP_EXPORT QXmppMessageHandler : public QXmppExtension
+{
+public:
+    virtual bool handleMessage(const QXmppMessage &) = 0;
+};
+
+#endif  // QXMPPMESSAGEHANDLER_H