Implement async DNS resolution using c-ares

fix #2533

1 files changed, 46 insertions, 0 deletions

diff --git a/src/network/dns_socket_handler.hpp b/src/network/dns_socket_handler.hpp
new file mode 100644
index 0000000..beb47d9
--- /dev/null
+++ b/src/network/dns_socket_handler.hpp
@@ -0,0 +1,46 @@
+#ifndef DNS_SOCKET_HANDLER_HPP
+# define DNS_SOCKET_HANDLER_HPP
+
+#include <config.h>
+#ifdef CARES_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)
+ */
+
+class DNSSocketHandler: public SocketHandler
+{
+public:
+  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, const socket_t socket);
+  ~DNSSocketHandler();
+  /**
+   * 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;
+  /**
+   * Do nothing, because we are always considered to be connected, since the
+   * connection is done by c-ares and not by us.
+   */
+  void connect() override final;
+  /**
+   * Always true, see the comment for connect()
+   */
+  bool is_connected() const override final;
+
+private:
+  DNSSocketHandler(const DNSSocketHandler&) = delete;
+  DNSSocketHandler(DNSSocketHandler&&) = delete;
+  DNSSocketHandler& operator=(const DNSSocketHandler&) = delete;
+  DNSSocketHandler& operator=(DNSSocketHandler&&) = delete;
+};
+
+#endif // CARES_FOUND
+#endif // DNS_SOCKET_HANDLER_HPP