Check for DSN extension support before using it.

src/vmime/net/dsnAttributes.cpp

@@ -58,6 +58,12 @@ string dsnAttributes::getEnvelopId() const {
 }
 
 
+bool dsnAttributes::isEmpty() const {
+
+	return m_notifications.empty() && m_returnFormat.empty() && m_envelopId.empty();
+}
+
+
 } // net
 } // vmime
 

src/vmime/net/dsnAttributes.hpp

@@ -90,6 +90,12 @@ class VMIME_EXPORT dsnAttributes : public object {
 	  */
 	string getEnvelopId() const;
 
+	/** Returns whether the object is empty, and no attribute has been set.
+	  *
+	  * @return true if object is empty, or false otherwise
+	  */
+	bool isEmpty() const;
+
 private:
 
 	string m_notifications;

src/vmime/net/smtp/SMTPExceptions.cpp

@@ -151,6 +151,59 @@ const char* SMTPMessageSizeExceedsCurLimitsException::name() const throw() {
 }
 
 
+//
+// SMTPExtensionNotSupportedException
+//
+
+SMTPExtensionNotSupportedException::SMTPExtensionNotSupportedException(const string &what, const exception& other)
+	: net_exception(what.empty() ? "A required extension is not supported by the SMTP server." : what, other) {
+
+}
+
+
+SMTPExtensionNotSupportedException::~SMTPExtensionNotSupportedException() throw() {
+
+}
+
+
+exception* SMTPExtensionNotSupportedException::clone() const {
+
+	return new SMTPExtensionNotSupportedException(*this);
+}
+
+
+const char* SMTPExtensionNotSupportedException::name() const throw() {
+
+	return "SMTPExtensionNotSupportedException";
+}
+
+
+//
+// SMTPDSNExtensionNotSupportedException
+//
+
+SMTPDSNExtensionNotSupportedException::SMTPDSNExtensionNotSupportedException(const exception& other)
+	: SMTPExtensionNotSupportedException("RFC-1891 DSN extension is not supported by the SMTP server.", other) {
+
+}
+
+
+SMTPDSNExtensionNotSupportedException::~SMTPDSNExtensionNotSupportedException() throw() {
+
+}
+
+
+exception* SMTPDSNExtensionNotSupportedException::clone() const {
+	return new SMTPDSNExtensionNotSupportedException(*this);
+}
+
+
+const char* SMTPDSNExtensionNotSupportedException::name() const throw() {
+
+	return "SMTPDSNExtensionNotSupportedException";
+}
+
+
 } // smtp
 } // net
 } // vmime

src/vmime/net/smtp/SMTPExceptions.hpp

@@ -120,6 +120,34 @@ class VMIME_EXPORT SMTPMessageSizeExceedsCurLimitsException : public exceptions:
 };
 
 
+/** SMTP error: a required extension is not supported by the server.
+  */
+class VMIME_EXPORT SMTPExtensionNotSupportedException : public exceptions::net_exception {
+
+public:
+
+	SMTPExtensionNotSupportedException(const string& what, const exception& other = NO_EXCEPTION);
+	~SMTPExtensionNotSupportedException() throw();
+
+	exception* clone() const;
+	const char* name() const throw();
+};
+
+
+/** SMTP error: RFC-1891 DSN extension is not supported by the server.
+  */
+class VMIME_EXPORT SMTPDSNExtensionNotSupportedException : public SMTPExtensionNotSupportedException {
+
+public:
+
+	SMTPDSNExtensionNotSupportedException(const exception& other = NO_EXCEPTION);
+	~SMTPDSNExtensionNotSupportedException() throw();
+
+	exception* clone() const;
+	const char* name() const throw();
+};
+
+
 } // smtp
 } // net
 } // vmime

src/vmime/net/smtp/SMTPTransport.cpp

@@ -186,13 +186,19 @@ void SMTPTransport::sendEnvelope(
 	const size_t size,
 	const dsnAttributes& dsnAttrs
 ) {
+
 	// If no recipient/expeditor was found, throw an exception
 	if (recipients.isEmpty()) {
 		throw exceptions::no_recipient();
 	} else if (expeditor.isEmpty()) {
 		throw exceptions::no_expeditor();
 	}
 
+	// If DSN extension is used, ensure it is supported by the server
+	if (!dsnAttrs.isEmpty() && !m_connection->hasExtension("DSN")) {
+		throw SMTPDSNExtensionNotSupportedException();
+	}
+
 
 	const bool needReset = m_needReset;
 	const bool hasPipelining = m_connection->hasExtension("PIPELINING") &&