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_handler.cpp

@@ -37,6 +37,7 @@ ares_channel& DNSHandler::get_channel()
 
 void DNSHandler::destroy()
 {
+  this->remove_all_sockets_from_poller();
   this->socket_handlers.clear();
   ::ares_destroy(this->channel);
   ::ares_library_cleanup();
@@ -95,7 +96,7 @@ void DNSHandler::watch_dns_sockets(std::shared_ptr<Poller>& poller)
           if (it == this->socket_handlers.end())
             {
               this->socket_handlers.emplace(this->socket_handlers.begin(),
-                                            std::make_unique<DNSSocketHandler>(poller, i));
+                                            std::make_unique<DNSSocketHandler>(poller, *this, i));
               it = this->socket_handlers.begin();
             }
           poller->add_socket_handler(it->get());
@@ -122,4 +123,12 @@ void DNSHandler::watch_dns_sockets(std::shared_ptr<Poller>& poller)
     }
 }
 
+void DNSHandler::remove_all_sockets_from_poller()
+{
+  for (const auto& socket_handler: this->socket_handlers)
+  {
+    socket_handler->remove_from_poller();
+  }
+}
+
 #endif /* CARES_FOUND */

louloulibs/network/dns_handler.hpp

@@ -40,6 +40,7 @@ public:
    * and library.
    */
   void destroy();
+  void remove_all_sockets_from_poller();
   ares_channel& get_channel();
 
   static DNSHandler instance;

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 */

louloulibs/network/dns_socket_handler.hpp

@@ -13,10 +13,12 @@
  * (Poller reported it to be writable or readeable)
  */
 
+class DNSHandler;
+
 class DNSSocketHandler: public SocketHandler
 {
 public:
-  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, const socket_t socket);
+  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, DNSHandler& handler, const socket_t socket);
   ~DNSSocketHandler() = default;
   DNSSocketHandler(const DNSSocketHandler&) = delete;
   DNSSocketHandler(DNSSocketHandler&&) = delete;
@@ -38,8 +40,10 @@ public:
    * Always true, see the comment for connect()
    */
   bool is_connected() const override final;
+  void remove_from_poller();
 
 private:
+  DNSHandler& handler;
 };
 
 #endif // CARES_FOUND