Fix: controld: leave xml-src attribute empty when no DC selected Clus…

…terLabs#2902

Right after starting the cluster the DC is offline for short time,
and if you call 'crmadmin --dc_lookup' during this time, it would hang.
This change leaves the xml-src attribute that the crmadmin receives from
the pacemaker-controld empty, so that crmadmin knows the DC was not
selected.
ref: https://projects.clusterlabs.org/T735

daemons/controld/controld_messages.c

@@ -23,11 +23,12 @@
 
 static enum crmd_fsa_input handle_message(xmlNode *msg,
                                           enum crmd_fsa_cause cause);
+static xmlNode* create_ping_reply(const xmlNode *msg);
 static void handle_response(xmlNode *stored_msg);
 static enum crmd_fsa_input handle_request(xmlNode *stored_msg,
                                           enum crmd_fsa_cause cause);
 static enum crmd_fsa_input handle_shutdown_request(xmlNode *stored_msg);
-static void send_msg_via_ipc(xmlNode * msg, const char *sys);
+static void send_msg_via_ipc(xmlNode * msg, const char *sys, const char *src);
 
 /* debug only, can wrap all it likes */
 static int last_data_id = 0;
@@ -439,6 +440,18 @@ relay_message(xmlNode * msg, gboolean originated_locally)
         }
     }
 
+    // If the DC is not yet selected
+    if ((strcmp(task, CRM_OP_PING) == 0) && (controld_globals.dc_name == NULL)) {
+        if (is_for_dc) {
+            xmlNode *reply = create_ping_reply(msg);
+            sys_to = crm_element_value(reply, PCMK__XA_CRM_SYS_TO);
+            // Explicitly leave src empty. It indicates that dc is "not yet selected"
+            send_msg_via_ipc(reply, sys_to, NULL);
+            pcmk__xml_free(reply);
+            return TRUE;
+        }
+    }
+
     // Check whether message should be relayed
 
     if (is_for_dc || is_for_dcib || is_for_te) {
@@ -447,7 +460,8 @@ relay_message(xmlNode * msg, gboolean originated_locally)
                 crm_trace("Route message %s locally as transition request",
                           ref);
                 crm_log_xml_trace(msg, sys_to);
-                send_msg_via_ipc(msg, sys_to);
+                send_msg_via_ipc(msg, sys_to, controld_globals.cluster->priv->node_name);
+
                 return TRUE; // No further processing of message is needed
             }
             crm_trace("Route message %s locally as DC request", ref);
@@ -483,7 +497,7 @@ relay_message(xmlNode * msg, gboolean originated_locally)
         }
         crm_trace("Relay message %s locally to %s", ref, sys_to);
         crm_log_xml_trace(msg, "IPC-relay");
-        send_msg_via_ipc(msg, sys_to);
+        send_msg_via_ipc(msg, sys_to, controld_globals.cluster->priv->node_name);
         return TRUE;
     }
 
@@ -809,8 +823,8 @@ handle_remote_state(const xmlNode *msg)
  *
  * \return Next FSA input
  */
-static enum crmd_fsa_input
-handle_ping(const xmlNode *msg)
+static xmlNode*
+create_ping_reply(const xmlNode *msg)
 {
     const char *value = NULL;
     xmlNode *ping = NULL;
@@ -831,9 +845,15 @@ handle_ping(const xmlNode *msg)
     // @TODO maybe do some checks to determine meaningful status
     crm_xml_add(ping, PCMK_XA_RESULT, "ok");
 
-    // Send reply
     reply = pcmk__new_reply(msg, ping);
     pcmk__xml_free(ping);
+    return reply;
+}
+
+static enum crmd_fsa_input
+handle_ping(const xmlNode *msg)
+{
+    xmlNode *reply = create_ping_reply(msg);
     if (reply != NULL) {
         (void) relay_message(reply, TRUE);
         pcmk__xml_free(reply);
@@ -1272,7 +1292,7 @@ handle_shutdown_request(xmlNode * stored_msg)
 }
 
 static void
-send_msg_via_ipc(xmlNode * msg, const char *sys)
+send_msg_via_ipc(xmlNode * msg, const char *sys, const char *src)
 {
     pcmk__client_t *client_channel = NULL;
 
@@ -1281,8 +1301,7 @@ send_msg_via_ipc(xmlNode * msg, const char *sys)
     client_channel = pcmk__find_client_by_id(sys);
 
     if (crm_element_value(msg, PCMK__XA_SRC) == NULL) {
-        crm_xml_add(msg, PCMK__XA_SRC,
-                    controld_globals.cluster->priv->node_name);
+        crm_xml_add(msg, PCMK__XA_SRC, src);
     }
 
     if (client_channel != NULL) {