- TLS revised (again)

- TLS Session resumption issues resolved
- Credential prompt has "Remember" checkbox initially selected when credentials originate from Windows Credential Manager
- Last authentication attempt failure notice is more general and no longer insinuate user credentials are the likely cause of the failure
- Additional log messages added

lib/TLS/src/Credentials.cpp

@@ -254,7 +254,7 @@ tstring eap::credentials_tls::get_name() const
 }
 
 
-bool eap::credentials_tls::combine(
+eap::credentials::source_t eap::credentials_tls::combine(
     _In_       const credentials_tls   *cred_cached,
     _In_       const config_method_tls &cfg,
     _In_opt_z_       LPCTSTR           pszTargetName)
@@ -263,14 +263,14 @@ bool eap::credentials_tls::combine(
         // Using EAP service cached credentials.
         *this = *cred_cached;
         m_module.log_event(&EAPMETHOD_TRACE_EVT_CRED_CACHED1, event_data((unsigned int)eap_type_tls), event_data(credentials_tls::get_name()), event_data::blank);
-        return true;
+        return source_cache;
     }
 
     if (cfg.m_use_preshared) {
         // Using preshared credentials.
         *this = *(credentials_tls*)cfg.m_preshared.get();
         m_module.log_event(&EAPMETHOD_TRACE_EVT_CRED_PRESHARED1, event_data((unsigned int)eap_type_tls), event_data(credentials_tls::get_name()), event_data::blank);
-        return true;
+        return source_preshared;
     }
 
     if (pszTargetName) {
@@ -281,13 +281,13 @@ bool eap::credentials_tls::combine(
             // Using stored credentials.
             *this = std::move(cred_loaded);
             m_module.log_event(&EAPMETHOD_TRACE_EVT_CRED_STORED1, event_data((unsigned int)eap_type_tls), event_data(credentials_tls::get_name()), event_data::blank);
-            return true;
+            return source_storage;
         } catch (...) {
             // Not actually an error.
         }
     }
 
-    return false;
+    return source_unknown;
 }