--- /dev/null
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_EV_DRIVER_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_EV_DRIVER_H
+
+#include <grpc/support/port_platform.h>
+
+#include <ares.h>
+#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
+#include "src/core/lib/gprpp/abstract.h"
+#include "src/core/lib/iomgr/pollset_set.h"
+
+typedef struct grpc_ares_ev_driver grpc_ares_ev_driver;
+
+/* Start \a ev_driver. It will keep working until all IO on its ares_channel is
+ done, or grpc_ares_ev_driver_destroy() is called. It may notify the callbacks
+ bound to its ares_channel when necessary. */
+void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver);
+
+/* Returns the ares_channel owned by \a ev_driver. To bind a c-ares query to
+ \a ev_driver, use the ares_channel owned by \a ev_driver as the arg of the
+ query. */
+ares_channel* grpc_ares_ev_driver_get_channel_locked(
+ grpc_ares_ev_driver* ev_driver);
+
+/* Creates a new grpc_ares_ev_driver. Returns GRPC_ERROR_NONE if \a ev_driver is
+ created successfully. */
+grpc_error* grpc_ares_ev_driver_create_locked(grpc_ares_ev_driver** ev_driver,
+ grpc_pollset_set* pollset_set,
+ int query_timeout_ms,
+ grpc_combiner* combiner,
+ grpc_ares_request* request);
+
+/* Called back when all DNS lookups have completed. */
+void grpc_ares_ev_driver_on_queries_complete_locked(
+ grpc_ares_ev_driver* ev_driver);
+
+/* Shutdown all the grpc_fds used by \a ev_driver */
+void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver);
+
+/* Exposed in this header for C-core tests only */
+extern void (*grpc_ares_test_only_inject_config)(ares_channel channel);
+
+namespace grpc_core {
+
+/* A wrapped fd that integrates with the grpc iomgr of the current platform.
+ * A GrpcPolledFd knows how to create grpc platform-specific iomgr endpoints
+ * from "ares_socket_t" sockets, and then sign up for readability/writeability
+ * with that poller, and do shutdown and destruction. */
+class GrpcPolledFd {
+ public:
+ virtual ~GrpcPolledFd() {}
+ /* Called when c-ares library is interested and there's no pending callback */
+ virtual void RegisterForOnReadableLocked(grpc_closure* read_closure)
+ GRPC_ABSTRACT;
+ /* Called when c-ares library is interested and there's no pending callback */
+ virtual void RegisterForOnWriteableLocked(grpc_closure* write_closure)
+ GRPC_ABSTRACT;
+ /* Indicates if there is data left even after just being read from */
+ virtual bool IsFdStillReadableLocked() GRPC_ABSTRACT;
+ /* Called once and only once. Must cause cancellation of any pending
+ * read/write callbacks. */
+ virtual void ShutdownLocked(grpc_error* error) GRPC_ABSTRACT;
+ /* Get the underlying ares_socket_t that this was created from */
+ virtual ares_socket_t GetWrappedAresSocketLocked() GRPC_ABSTRACT;
+ /* A unique name, for logging */
+ virtual const char* GetName() GRPC_ABSTRACT;
+
+ GRPC_ABSTRACT_BASE_CLASS
+};
+
+/* A GrpcPolledFdFactory is 1-to-1 with and owned by the
+ * ares event driver. It knows how to create GrpcPolledFd's
+ * for the current platform, and the ares driver uses it for all of
+ * its fd's. */
+class GrpcPolledFdFactory {
+ public:
+ virtual ~GrpcPolledFdFactory() {}
+ /* Creates a new wrapped fd for the current platform */
+ virtual GrpcPolledFd* NewGrpcPolledFdLocked(
+ ares_socket_t as, grpc_pollset_set* driver_pollset_set,
+ grpc_combiner* combiner) GRPC_ABSTRACT;
+ /* Optionally configures the ares channel after creation */
+ virtual void ConfigureAresChannelLocked(ares_channel channel) GRPC_ABSTRACT;
+
+ GRPC_ABSTRACT_BASE_CLASS
+};
+
+UniquePtr<GrpcPolledFdFactory> NewGrpcPolledFdFactory(grpc_combiner* combiner);
+
+} // namespace grpc_core
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_EV_DRIVER_H \
+ */