Use udns instead of c-ares

fix #3226

louloulibs/network/dns_socket_handler.hpp

@@ -1,44 +1,33 @@
 #pragma once
 
 #include <louloulibs.h>
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
 
 #include <network/socket_handler.hpp>
-#include <ares.h>
 
 /**
- * Manage a socket returned by ares_fds. We do not create, open or close the
- * socket ourself: this is done by c-ares.  We just call ares_process_fd()
- * with the correct parameters, depending on what can be done on that socket
- * (Poller reported it to be writable or readeable)
+ * Manage the UDP socket provided by udns, we do not create, open or close the
+ * socket ourself: this is done by udns.  We only watch it for readability
  */
-
-class DNSHandler;
-
 class DNSSocketHandler: public SocketHandler
 {
 public:
-  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, DNSHandler& handler, const socket_t socket);
-  ~DNSSocketHandler() = default;
+  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, const socket_t socket);
+  ~DNSSocketHandler();
   DNSSocketHandler(const DNSSocketHandler&) = delete;
   DNSSocketHandler(DNSSocketHandler&&) = delete;
   DNSSocketHandler& operator=(const DNSSocketHandler&) = delete;
   DNSSocketHandler& operator=(DNSSocketHandler&&) = delete;
 
-  /**
-   * Just call dns_process_fd, c-ares will do its work of send()ing or
-   * recv()ing the data it wants on that socket.
-   */
   void on_recv() override final;
-  void on_send() override final;
+
   /**
    * Always true, see the comment for connect()
    */
   bool is_connected() const override final;
-  void remove_from_poller();
 
-private:
-  DNSHandler& handler;
+  void watch();
+  void unwatch();
 };
 
-#endif // CARES_FOUND
+#endif // UDNS_FOUND