Add handler for 410 response, notifying invalid cap commands

client/handlers.go

@@ -20,6 +20,7 @@ var intHandlers = map[string]HandlerFunc{
 	NICK:     (*Conn).h_NICK,
 	PING:     (*Conn).h_PING,
 	CAP:      (*Conn).h_CAP,
+	"410":    (*Conn).h_410,
 }
 
 // set up the ircv3 capabilities supported by this client which will be requested by default to the server.
@@ -151,6 +152,11 @@ func (c *capSet) Size() int {
 	return len(c.caps)
 }
 
+// This handler is triggered when an invalid cap command is received by the server.
+func (conn *Conn) h_410(line *Line) {
+	logging.Warn("Invalid cap subcommand: ", line.Args[1])
+}
+
 // Handler for capability negotiation commands.
 // Note that even if multiple CAP_END commands may be sent to the server during negotiation,
 // only the first will be considered.