QDBus: Transform fallback interface names according to the spec

ACE-encode the domain names, replace dashes with underscores,
prepend underscore to domain name parts that start with a digit.

Add a regression test into tst_qdbusinterface.

Fixes: QTBUG-71674
Change-Id: I92e0c6889163c0eccc4c833f2058d759631f562c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

2 files changed, 95 insertions, 15 deletions

diff --git a/src/dbus/qdbusmisc.cpp b/src/dbus/qdbusmisc.cpp
index 502624cd66..5a9d8f548f 100644
--- a/src/dbus/qdbusmisc.cpp
+++ b/src/dbus/qdbusmisc.cpp
@@ -8,6 +8,7 @@
 #include <QtCore/qlist.h>
 #include <QtCore/qmetaobject.h>
 #include <QtCore/qvariant.h>
+#include <private/qurl_p.h>
 
 #include "qdbusutil_p.h"
 #include "qdbusconnection_p.h"
@@ -58,23 +59,42 @@ QString qDBusInterfaceFromMetaObject(const QMetaObject *mo)
         } else if (!QCoreApplication::instance()||
                    QCoreApplication::instance()->applicationName().isEmpty()) {
             interface.prepend("local."_L1);
-         } else {
-            interface.prepend(u'.').prepend(QCoreApplication::instance()->applicationName());
+        } else {
+            QString domainName = QCoreApplication::instance()->applicationName();
             const QString organizationDomain = QCoreApplication::instance()->organizationDomain();
-            const auto domainName = QStringView{organizationDomain}.split(u'.', Qt::SkipEmptyParts);
-            if (domainName.isEmpty()) {
-                 interface.prepend("local."_L1);
-            } else {
-                QString composedDomain;
-                // + 1 for additional dot, e.g. organizationDomain equals "example.com",
-                // then composedDomain will be equal "com.example."
-                composedDomain.reserve(organizationDomain.size() + 1);
-                for (auto it = domainName.rbegin(), end = domainName.rend(); it != end; ++it)
-                    composedDomain += *it + u'.';
-
-                interface.prepend(composedDomain);
+            if (organizationDomain.isEmpty())
+                domainName.append(".local"_L1);
+            else
+                domainName.append(u'.').append(organizationDomain);
+
+            // Domain names used to produce interface names should be IDN-encoded.
+            QString encodedDomainName = qt_ACE_do(domainName, ToAceOnly, ForbidLeadingDot);
+            if (encodedDomainName.isEmpty()) {
+                interface.prepend("local."_L1);
+                return interface;
             }
-         }
+
+            // Hyphens are not allowed in interface names and should be replaced
+            // by underscores.
+            encodedDomainName.replace(u'-', u'_');
+
+            auto nameParts = QStringView{ encodedDomainName }.split(u'.', Qt::SkipEmptyParts);
+
+            QString composedDomain;
+            // + 1 for additional dot, e.g. domainName equals "App.example.com",
+            // then composedDomain will be equal "com.example.App."
+            composedDomain.reserve(encodedDomainName.size() + nameParts.size() + 1);
+            for (auto it = nameParts.rbegin(), end = nameParts.rend(); it != end; ++it) {
+                // An interface name cannot start with a digit, and cannot
+                // contain digits immediately following a period. Prefix such
+                // digits with underscores.
+                if (it->first().isDigit())
+                    composedDomain += u'_';
+                composedDomain += *it + u'.';
+            }
+
+            interface.prepend(composedDomain);
+        }
      }
 
     return interface;
diff --git a/tests/auto/dbus/qdbusinterface/tst_qdbusinterface.cpp b/tests/auto/dbus/qdbusinterface/tst_qdbusinterface.cpp
index d4b61d27dd..b5e2aa9599 100644
--- a/tests/auto/dbus/qdbusinterface/tst_qdbusinterface.cpp
+++ b/tests/auto/dbus/qdbusinterface/tst_qdbusinterface.cpp
@@ -20,6 +20,8 @@
 #include "../qdbusmarshall/common.h"
 #include "myobject.h"
 
+using namespace Qt::StringLiterals;
+
 #define TEST_INTERFACE_NAME "org.qtproject.QtDBus.MyObject"
 #define TEST_SIGNAL_NAME "somethingHappened"
 
@@ -198,6 +200,10 @@ private slots:
     void complexPropertyWritePeer();
 
     void interactiveAuthorizationRequired();
+
+    void interfaceNameFallback_data();
+    void interfaceNameFallback();
+
 private:
     QProcess proc;
 };
@@ -1147,6 +1153,60 @@ void tst_QDBusInterface::interactiveAuthorizationRequired()
     QVERIFY(reply.arguments().at(0).toBool());
 }
 
+class TestObject : public QObject
+{
+    Q_OBJECT
+public Q_SLOTS:
+    void test() { }
+};
+
+void tst_QDBusInterface::interfaceNameFallback_data()
+{
+    QTest::addColumn<QString>("appName");
+    QTest::addColumn<QString>("orgDomain");
+    QTest::addColumn<QString>("interfaceName");
+
+    QTest::addRow("empty.empty") << "" << "" << "local.tst_qdbusinterface";
+    QTest::addRow("with-domain") << "" << "qt-project.org" << "org.qt_project.tst_qdbusinterface";
+    QTest::addRow("numbers") << "prog42" << "7-zip.org" << "org._7_zip.prog42";
+    QTest::addRow("non-latin1") << u"\u00e6"_s << u"\u00e5"_s << "xn__5ca.xn__6ca";
+}
+
+void tst_QDBusInterface::interfaceNameFallback()
+{
+    QFETCH(QString, appName);
+    QFETCH(QString, orgDomain);
+    QFETCH(QString, interfaceName);
+
+    auto app = QCoreApplication::instance();
+    auto oldApplicationName = app->applicationName();
+    auto oldOrganizationDomain = app->organizationDomain();
+
+    app->setApplicationName(appName);
+    app->setOrganizationDomain(orgDomain);
+    auto obj = new TestObject;
+
+    auto cleanup = qScopeGuard([&] {
+        obj->deleteLater();
+        app->setApplicationName(oldApplicationName);
+        app->setOrganizationDomain(oldOrganizationDomain);
+    });
+
+    auto con = QDBusConnection::sessionBus();
+    const QString path = "/interfaceNameFallback"_L1;
+
+    QVERIFY(con.registerObject(path, obj, QDBusConnection::ExportAllContents));
+
+    QDBusInterface interface(con.baseService(), path, "org.freedesktop.DBus.Introspectable"_L1,
+                             con);
+    auto reply = interface.call("Introspect");
+
+    QCOMPARE(reply.type(), QDBusMessage::ReplyMessage);
+    QString tag = u"<interface name=\"%1.TestObject\">"_s.arg(interfaceName);
+    auto result = reply.arguments().at(0).toString();
+    QVERIFY2(result.contains(tag), qUtf8Printable(u"Tag '%1' not found\n%2"_s.arg(tag, result)));
+}
+
 QTEST_MAIN(tst_QDBusInterface)
 
 #include "tst_qdbusinterface.moc"