SSL updates

src/kvilib/net/KviSSL.cpp

@@ -378,11 +378,23 @@ bool KviSSL::initContext(Method m)
 		SSL_CTX_set_verify(m_pSSLCtx, SSL_VERIFY_PEER, verify_clientCallback);
 	}
 
+	SSL_CTX_set_options (m_pSSLCtx,
+		// disable old, unsecure protocols
+		SSL_OP_NO_SSLv2|SSL_OP_NO_SSLv3
+		|SSL_OP_NO_TLSv1|SSL_OP_NO_TLSv1_1
+		// disable unsecure defaults on old openSSL versions
+#ifdef SSL_OP_NO_COMPRESSION
+		|SSL_OP_NO_COMPRESSION
+#endif
+#ifdef SSL_OP_SINGLE_DH_USE
+		|SSL_OP_SINGLE_DH_USE
+#endif
+#ifdef SSL_OP_SINGLE_ECDH_USE
+		|SSL_OP_SINGLE_ECDH_USE
+#endif
+	);
 	// we want all ciphers to be available here, except insecure ones, orderer by strength;
-	// ADH are moved to the end since they are less secure, but they don't need a certificate
-	// (so we can use secure dcc without a cert)
-	// NOTE: see bug ticket #155
-	SSL_CTX_set_cipher_list(m_pSSLCtx, "ALL:!eNULL:!EXP:!SSLv2:+ADH@STRENGTH");
+	SSL_CTX_set_cipher_list(m_pSSLCtx, "ALL:!eNULL:!LOW:!EXP:!SSLv2:!SSLv3:!TLSv1:@STRENGTH");
 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
 	SSL_CTX_set_dh_auto(m_pSSLCtx, 1);
 #else
@@ -391,6 +403,21 @@ bool KviSSL::initContext(Method m)
 	return true;
 }
 
+bool KviSSL::enableADHCiphers()
+{
+	if(!m_pSSLCtx)
+		return false;
+	if(!m_pSSL)
+		return false;
+	// Add Anonymous DH cipher suites to the list of available ciphers.
+	// ADH don't need a certificate, so we can use secure dcc without a cert)
+	// They are moved to the end since they are considered NOT SECURE since at least 2015's Logjam
+	// NOTE: see bug ticket #155
+	if(!SSL_set_cipher_list(m_pSSL, "ALL:!eNULL:!LOW:!EXP:!SSLv2:!SSLv3:!TLSv1:+ADH:+AECDH:@STRENGTH:@SECLEVEL=0"))
+		return false;
+	return true;
+}
+
 bool KviSSL::initSocket(kvi_socket_t fd)
 {
 	if(!m_pSSLCtx)
@@ -498,6 +525,13 @@ bool KviSSL::getLastErrorString(KviCString & buffer, bool bPeek)
 	return false;
 }
 
+bool KviSSL::setTLSHostname(const char * name)
+{
+	if(!m_pSSL)
+		return false;
+	return SSL_set_tlsext_host_name(m_pSSL, name) ? true : false;
+}
+
 KviSSL::Result KviSSL::connect()
 {
 	if(!m_pSSL)

src/kvilib/net/KviSSL.h

@@ -192,6 +192,8 @@ class KVILIB_API KviSSL
 	bool initSocket(kvi_socket_t fd);
 	bool initContext(KviSSL::Method m);
 	void shutdown();
+	bool setTLSHostname(const char * name);
+	bool enableADHCiphers();
 	KviSSL::Result connect();
 	KviSSL::Result accept();
 	int read(char * buffer, int len);

src/kvirc/kernel/KviIrcSocket.cpp

@@ -1356,6 +1356,9 @@ void KviIrcSocket::doSSLHandshake(int)
 		return; // ops ?
 	}
 
+	// TLS: Set SNI hostname
+	m_pSSL->setTLSHostname(m_pIrcServer->hostName().toUtf8().data());
+
 	switch(m_pSSL->connect())
 	{
 		case KviSSL::Success:

src/modules/dcc/DccMarshal.cpp

@@ -602,6 +602,10 @@ void DccMarshal::doSSLHandshake(int)
 		return; // ops ?
 	}
 
+	// Enable the use of Anonymous DH cipher suites, to permit connection without a certificate
+	// Note: this is considered NOT SECURE since at least 2015 (Logjam), but it's still better than plain text
+	m_pSSL->enableADHCiphers();
+
 	KviSSL::Result r = m_bOutgoing ? m_pSSL->connect() : m_pSSL->accept();
 
 	switch(r)