Always remove all the DNS sockets on an c-ares event

Because c-ares may close one of its socket, even if it’s not the one that
has the event. Otherwise we may not know when a socket has been removed from
our poller (automatically, when close()ed) and this leads to bugs.

louloulibs/network/dns_socket_handler.cpp

@@ -8,8 +8,10 @@
 #include <ares.h>
 
 DNSSocketHandler::DNSSocketHandler(std::shared_ptr<Poller> poller,
+                                   DNSHandler& handler,
                                    const socket_t socket):
-  SocketHandler(poller, socket)
+  SocketHandler(poller, socket),
+  handler(handler)
 {
 }
 
@@ -21,7 +23,7 @@ void DNSSocketHandler::on_recv()
 {
   // always stop watching send and read events. We will re-watch them if the
   // next call to ares_fds tell us to
-  this->poller->remove_socket_handler(this->socket);
+  this->handler.remove_all_sockets_from_poller();
   ::ares_process_fd(DNSHandler::instance.get_channel(), this->socket, ARES_SOCKET_BAD);
 }
 
@@ -29,7 +31,7 @@ void DNSSocketHandler::on_send()
 {
   // always stop watching send and read events. We will re-watch them if the
   // next call to ares_fds tell us to
-  this->poller->remove_socket_handler(this->socket);
+  this->handler.remove_all_sockets_from_poller();
   ::ares_process_fd(DNSHandler::instance.get_channel(), ARES_SOCKET_BAD, this->socket);
 }
 
@@ -38,4 +40,9 @@ bool DNSSocketHandler::is_connected() const
   return true;
 }
 
+void DNSSocketHandler::remove_from_poller()
+{
+  this->poller->remove_socket_handler(this->socket);
+}
+
 #endif /* CARES_FOUND */