Add SMTPS with AUTH PLAIN without SASL

GNU SASL is a nice library but comes with its own prerequisites and dependencies.
As IMAP and POP3 are able to work without SASL it seems to me logical to add some authentication support to SMTP too. As these days most of the communication is encrypted it is common to use simple mechanism like AUTH PLAIN, so I have added it.

1 files changed, 37 insertions, 1 deletions

diff --git a/src/vmime/net/smtp/SMTPConnection.cpp b/src/vmime/net/smtp/SMTPConnection.cpp
index 3785126a..8709efe4 100644
--- a/src/vmime/net/smtp/SMTPConnection.cpp
+++ b/src/vmime/net/smtp/SMTPConnection.cpp
@@ -40,6 +40,10 @@
 
 #if VMIME_HAVE_SASL_SUPPORT
 	#include "vmime/security/sasl/SASLContext.hpp"
+#else
+	#include "vmime/utility/encoder/b64Encoder.hpp"
+	#include "vmime/utility/inputStreamStringAdapter.hpp"
+	#include "vmime/utility/outputStreamStringAdapter.hpp"
 #endif // VMIME_HAVE_SASL_SUPPORT
 
 #if VMIME_HAVE_TLS_SUPPORT
@@ -48,7 +52,6 @@
 #endif // VMIME_HAVE_TLS_SUPPORT
 
 
-
 // Helpers for service properties
 #define GET_PROPERTY(type, prop) \
 	(m_transport.lock()->getInfos().getPropertyValue <type>(getSession(), \
@@ -307,6 +310,39 @@ void SMTPConnection::authenticate()
 			throw;
 		}
 	}
+#else  // no SASL
+
+	// allow AUTH PLAIN over TLS - it is a popular and simple mechanism
+	if (m_secured)
+	{
+		std::vector <string> authMechs;
+		hasExtension("AUTH", &authMechs);
+
+		if (authMechs.empty())
+			throw exceptions::authentication_error("No AUTH mechanism available.");
+
+		const string plain("PLAIN");
+		if (std::find(authMechs.begin(), authMechs.end(), plain) != authMechs.end())
+		{
+			const string username = getAuthenticator()->getUsername();
+			const string password = getAuthenticator()->getPassword();
+			const string authToken = username + '\0' + username + '\0' + password;
+			auto encoder = new vmime::utility::encoder::b64Encoder();
+			utility::inputStreamStringAdapter in(authToken);
+			string authTokenBase64;
+			utility::outputStreamStringAdapter out(authTokenBase64);
+			encoder->encode(in, out);
+			sendRequest(SMTPCommand::AUTH(plain, authTokenBase64));
+			shared_ptr <SMTPResponse> response = readResponse();
+			const int code = response ? response->getCode() : -1;
+			if (code == 235)
+			{
+				m_authenticated = true;
+				return;
+			}
+		}
+	}
+
 #endif // VMIME_HAVE_SASL_SUPPORT
 
 	// No other authentication method is possible