Show message when server does not support ping

src/command/cmd_funcs.c

@@ -5863,6 +5863,11 @@ cmd_ping(ProfWin *window, const char *const command, gchar **args)
         return TRUE;
     }
 
+    if (args[0] == NULL && connection_supports(XMPP_FEATURE_PING) == FALSE) {
+        cons_show("Server does not support ping requests.");
+        return TRUE;
+    }
+
     iq_send_ping(args[0]);
 
     if (args[0] == NULL) {

src/xmpp/xmpp.h

@@ -55,6 +55,7 @@
 #define JABBER_PRIORITY_MIN -128
 #define JABBER_PRIORITY_MAX 127
 
+#define XMPP_FEATURE_PING "urn:xmpp:ping"
 #define XMPP_FEATURE_BLOCKING "urn:xmpp:blocking"
 #define XMPP_FEATURE_RECEIPTS "urn:xmpp:receipts"
 #define XMPP_FEATURE_LASTACTIVITY "jabber:iq:last"