StartTlsPacket: Fix UB when parsing invalid type

2 files changed, 12 insertions, 5 deletions

diff --git a/src/base/QXmppStartTlsPacket.cpp b/src/base/QXmppStartTlsPacket.cpp
index f4c5e2fb..445f519e 100644
--- a/src/base/QXmppStartTlsPacket.cpp
+++ b/src/base/QXmppStartTlsPacket.cpp
@@ -65,14 +65,20 @@ void QXmppStartTlsPacket::parse(const QDomElement &element)
     if (!QXmppStartTlsPacket::isStartTlsPacket(element))
         return;
 
-    m_type = Type(STARTTLS_TYPES.indexOf(element.tagName()));
+    if (auto index = STARTTLS_TYPES.indexOf(element.tagName()); index >= 0) {
+        m_type = Type(index);
+    } else {
+        m_type = Invalid;
+    }
 }
 
 void QXmppStartTlsPacket::toXml(QXmlStreamWriter *writer) const
 {
-    writer->writeStartElement(STARTTLS_TYPES.at(int(m_type)));
-    writer->writeDefaultNamespace(ns_tls);
-    writer->writeEndElement();
+    if (m_type != Invalid) {
+        writer->writeStartElement(STARTTLS_TYPES.at(int(m_type)));
+        writer->writeDefaultNamespace(ns_tls);
+        writer->writeEndElement();
+    }
 }
 /// \endcond
 
diff --git a/src/base/QXmppStartTlsPacket.h b/src/base/QXmppStartTlsPacket.h
index 9b91bef9..5396f5d9 100644
--- a/src/base/QXmppStartTlsPacket.h
+++ b/src/base/QXmppStartTlsPacket.h
@@ -39,7 +39,8 @@ public:
     enum Type {
         StartTls,  ///< Used by the client to initiate STARTTLS.
         Proceed,   ///< Used by the server to accept STARTTLS.
-        Failure    ///< Used by the server to reject STARTTLS.
+        Failure,   ///< Used by the server to reject STARTTLS.
+        Invalid,   ///< Invalid type
     };
 
     QXmppStartTlsPacket(Type type = StartTls);