[evolution-data-server/gnome-3-24] Prevent busy-loop opening Google calendar configured in GOA

[Milan Crha <mcrha src gnome org>]

commit d4d9f16f578a8efc35c6c103464d9eb632576b2b
Author: Milan Crha <mcrha redhat com>
Date:   Tue May 23 08:47:02 2017 +0200

    Prevent busy-loop opening Google calendar configured in GOA
    
    The change prevents constant ping-pong with source registry when
    trying multiple times in a row with empty credentials and the backend
    returning 'REQUIRED', which can misbehave with OAuth2 tokens.

 src/libebackend/e-backend.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/src/libebackend/e-backend.c b/src/libebackend/e-backend.c
index 389b9b4..5014853 100644
--- a/src/libebackend/e-backend.c
+++ b/src/libebackend/e-backend.c
@@ -58,6 +58,7 @@ struct _EBackendPrivate {
        GMainContext *main_context;
        GSocketConnectable *connectable;
        gboolean online;
+       gboolean tried_with_empty_credentials;
 
        GNetworkMonitor *network_monitor;
        gulong network_changed_handler_id;
@@ -288,6 +289,7 @@ backend_source_authenticate_thread (gpointer user_data)
        AuthenticateThreadData *thread_data = user_data;
        gchar *certificate_pem = NULL;
        GTlsCertificateFlags certificate_errors = 0;
+       gboolean empty_crendetials;
        GError *local_error = NULL;
        ESource *source;
 
@@ -310,6 +312,17 @@ backend_source_authenticate_thread (gpointer user_data)
        auth_result = e_backend_authenticate_sync (thread_data->backend, thread_data->credentials,
                &certificate_pem, &certificate_errors, thread_data->cancellable, &local_error);
 
+       empty_crendetials = auth_result == E_SOURCE_AUTHENTICATION_REQUIRED &&
+               (!thread_data->credentials || !e_named_parameters_count (thread_data->credentials));
+
+       if (empty_crendetials && thread_data->backend->priv->tried_with_empty_credentials) {
+               /* When tried repeatedly with empty credentials and both resulted in 'REQUIRED',
+                  then change it to 'REJECTED' to avoid loop. */
+               auth_result = E_SOURCE_AUTHENTICATION_REJECTED;
+       }
+
+       thread_data->backend->priv->tried_with_empty_credentials = empty_crendetials;
+
        if (!g_cancellable_is_cancelled (thread_data->cancellable)) {
                ESourceCredentialsReason reason = E_SOURCE_CREDENTIALS_REASON_ERROR;
 
@@ -725,6 +738,7 @@ e_backend_init (EBackend *backend)
        backend->priv = E_BACKEND_GET_PRIVATE (backend);
        backend->priv->prompter = e_user_prompter_new ();
        backend->priv->main_context = g_main_context_ref_thread_default ();
+       backend->priv->tried_with_empty_credentials = FALSE;
 
        g_mutex_init (&backend->priv->property_lock);
        g_mutex_init (&backend->priv->update_online_state_lock);