Separate the posix part of the c-ares driver

16 files changed, 401 insertions, 264 deletions

diff --git a/BUILD b/BUILD
index 3df4be8354..44b877705e 100644
--- a/BUILD
+++ b/BUILD
@@ -1333,6 +1333,7 @@ grpc_cc_library(
     name = "grpc_resolver_dns_ares",
     srcs = [
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc",
+        "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc",
         "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc",
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1bcac91020..4dc8d98b87 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1213,6 +1213,7 @@ add_library(grpc
   src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
   src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
+  src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
@@ -2503,6 +2504,7 @@ add_library(grpc_unsecure
   src/core/ext/transport/inproc/inproc_plugin.cc
   src/core/ext/transport/inproc/inproc_transport.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
+  src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
   src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
diff --git a/Makefile b/Makefile
index 1b4fc6a49a..ab6045191d 100644
--- a/Makefile
+++ b/Makefile
@@ -3588,6 +3588,7 @@ LIBGRPC_SRC = \
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
+    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc \
@@ -4844,6 +4845,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/transport/inproc/inproc_plugin.cc \
     src/core/ext/transport/inproc/inproc_transport.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
+    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc \
diff --git a/build.yaml b/build.yaml
index ffe2febcc5..11060b6ddd 100644
--- a/build.yaml
+++ b/build.yaml
@@ -725,6 +725,7 @@ filegroups:
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h
   src:
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
+  - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
   - src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
diff --git a/config.m4 b/config.m4
index 8190485249..a5b041f035 100644
--- a/config.m4
+++ b/config.m4
@@ -370,6 +370,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
+    src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc \
     src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc \
diff --git a/config.w32 b/config.w32
index db7679ce53..cd51b4d97c 100644
--- a/config.w32
+++ b/config.w32
@@ -346,6 +346,7 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\pick_first\\pick_first.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\round_robin\\round_robin.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\dns_resolver_ares.cc " +
+    "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_ev_driver.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_ev_driver_posix.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_wrapper.cc " +
     "src\\core\\ext\\filters\\client_channel\\resolver\\dns\\c_ares\\grpc_ares_wrapper_fallback.cc " +
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index 399368bab9..ca6df16a06 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -785,6 +785,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
                       'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc',
diff --git a/grpc.gemspec b/grpc.gemspec
index 5ab3713683..1a3b5bd889 100644
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -725,6 +725,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc )
+  s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc )
   s.files += %w( src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc )
diff --git a/grpc.gyp b/grpc.gyp
index f893862062..20e463ed9e 100644
--- a/grpc.gyp
+++ b/grpc.gyp
@@ -536,6 +536,7 @@
         'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
         'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
+        'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc',
@@ -1246,6 +1247,7 @@
         'src/core/ext/transport/inproc/inproc_plugin.cc',
         'src/core/ext/transport/inproc/inproc_transport.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
+        'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc',
         'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc',
diff --git a/package.xml b/package.xml
index 220256c11f..5be18bd4d0 100644
--- a/package.xml
+++ b/package.xml
@@ -730,6 +730,7 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc" role="src" />
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
new file mode 100644
index 0000000000..06a6e853f5
--- /dev/null
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
@@ -0,0 +1,311 @@
+/*
+ *
+ * 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.
+ *
+ */
+#include <grpc/support/port_platform.h>
+
+#include "src/core/lib/iomgr/port.h"
+#if GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET_ARES_EV_DRIVER)
+
+#include <ares.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/time.h>
+#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/iomgr/ev_posix.h"
+#include "src/core/lib/iomgr/iomgr_internal.h"
+#include "src/core/lib/iomgr/sockaddr_utils.h"
+
+typedef struct fd_node {
+  /** the owner of this fd node */
+  grpc_ares_ev_driver* ev_driver;
+  /** a closure wrapping on_readable_locked, which should be
+     invoked when the grpc_fd in this node becomes readable. */
+  grpc_closure read_closure;
+  /** a closure wrapping on_writable_locked, which should be
+     invoked when the grpc_fd in this node becomes writable. */
+  grpc_closure write_closure;
+  /** next fd node in the list */
+  struct fd_node* next;
+
+  /** wrapped fd that's polled by grpc's poller for the current platform */
+  grpc_core::GrpcPolledFd* grpc_polled_fd;
+  /** if the readable closure has been registered */
+  bool readable_registered;
+  /** if the writable closure has been registered */
+  bool writable_registered;
+  /** if the fd has been shutdown yet from grpc iomgr perspective */
+  bool already_shutdown;
+} fd_node;
+
+struct grpc_ares_ev_driver {
+  /** the ares_channel owned by this event driver */
+  ares_channel channel;
+  /** pollset set for driving the IO events of the channel */
+  grpc_pollset_set* pollset_set;
+  /** refcount of the event driver */
+  gpr_refcount refs;
+
+  /** combiner to synchronize c-ares and I/O callbacks on */
+  grpc_combiner* combiner;
+  /** a list of grpc_fd that this event driver is currently using. */
+  fd_node* fds;
+  /** is this event driver currently working? */
+  bool working;
+  /** is this event driver being shut down */
+  bool shutting_down;
+};
+
+static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver);
+
+static grpc_ares_ev_driver* grpc_ares_ev_driver_ref(
+    grpc_ares_ev_driver* ev_driver) {
+  gpr_log(GPR_DEBUG, "Ref ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
+  gpr_ref(&ev_driver->refs);
+  return ev_driver;
+}
+
+static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver* ev_driver) {
+  gpr_log(GPR_DEBUG, "Unref ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
+  if (gpr_unref(&ev_driver->refs)) {
+    gpr_log(GPR_DEBUG, "destroy ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
+    GPR_ASSERT(ev_driver->fds == nullptr);
+    GRPC_COMBINER_UNREF(ev_driver->combiner, "free ares event driver");
+    ares_destroy(ev_driver->channel);
+    gpr_free(ev_driver);
+  }
+}
+
+static void fd_node_destroy_locked(fd_node* fdn) {
+  gpr_log(GPR_DEBUG, "delete fd: %s", fdn->grpc_polled_fd->GetName());
+  GPR_ASSERT(!fdn->readable_registered);
+  GPR_ASSERT(!fdn->writable_registered);
+  GPR_ASSERT(fdn->already_shutdown);
+  grpc_core::Delete(fdn->grpc_polled_fd);
+  gpr_free(fdn);
+}
+
+static void fd_node_shutdown_locked(fd_node* fdn, const char* reason) {
+  if (!fdn->already_shutdown) {
+    fdn->already_shutdown = true;
+    fdn->grpc_polled_fd->ShutdownLocked(
+        GRPC_ERROR_CREATE_FROM_STATIC_STRING(reason));
+  }
+}
+
+grpc_error* grpc_ares_ev_driver_create_locked(grpc_ares_ev_driver** ev_driver,
+                                              grpc_pollset_set* pollset_set,
+                                              grpc_combiner* combiner) {
+  *ev_driver = static_cast<grpc_ares_ev_driver*>(
+      gpr_malloc(sizeof(grpc_ares_ev_driver)));
+  ares_options opts;
+  memset(&opts, 0, sizeof(opts));
+  opts.flags |= ARES_FLAG_STAYOPEN;
+  int status = ares_init_options(&(*ev_driver)->channel, &opts, ARES_OPT_FLAGS);
+  grpc_core::ConfigureAresChannelLocked(&(*ev_driver)->channel);
+  gpr_log(GPR_DEBUG, "grpc_ares_ev_driver_create_locked");
+  if (status != ARES_SUCCESS) {
+    char* err_msg;
+    gpr_asprintf(&err_msg, "Failed to init ares channel. C-ares error: %s",
+                 ares_strerror(status));
+    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_msg);
+    gpr_free(err_msg);
+    gpr_free(*ev_driver);
+    return err;
+  }
+  (*ev_driver)->combiner = GRPC_COMBINER_REF(combiner, "ares event driver");
+  gpr_ref_init(&(*ev_driver)->refs, 1);
+  (*ev_driver)->pollset_set = pollset_set;
+  (*ev_driver)->fds = nullptr;
+  (*ev_driver)->working = false;
+  (*ev_driver)->shutting_down = false;
+  return GRPC_ERROR_NONE;
+}
+
+void grpc_ares_ev_driver_destroy_locked(grpc_ares_ev_driver* ev_driver) {
+  // We mark the event driver as being shut down. If the event driver
+  // is working, grpc_ares_notify_on_event_locked will shut down the
+  // fds; if it's not working, there are no fds to shut down.
+  ev_driver->shutting_down = true;
+  grpc_ares_ev_driver_unref(ev_driver);
+}
+
+void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver) {
+  ev_driver->shutting_down = true;
+  fd_node* fn = ev_driver->fds;
+  while (fn != nullptr) {
+    fd_node_shutdown_locked(fn, "grpc_ares_ev_driver_shutdown");
+    fn = fn->next;
+  }
+}
+
+// Search fd in the fd_node list head. This is an O(n) search, the max possible
+// value of n is ARES_GETSOCK_MAXNUM (16). n is typically 1 - 2 in our tests.
+static fd_node* pop_fd_node_locked(fd_node** head, ares_socket_t as) {
+  fd_node dummy_head;
+  dummy_head.next = *head;
+  fd_node* node = &dummy_head;
+  while (node->next != nullptr) {
+    if (node->next->grpc_polled_fd->GetWrappedAresSocketLocked() == as) {
+      fd_node* ret = node->next;
+      node->next = node->next->next;
+      *head = dummy_head.next;
+      return ret;
+    }
+    node = node->next;
+  }
+  return nullptr;
+}
+
+static void on_readable_locked(void* arg, grpc_error* error) {
+  fd_node* fdn = static_cast<fd_node*>(arg);
+  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
+  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
+  fdn->readable_registered = false;
+  gpr_log(GPR_DEBUG, "readable on %s", fdn->grpc_polled_fd->GetName());
+  if (error == GRPC_ERROR_NONE) {
+    do {
+      ares_process_fd(ev_driver->channel, as, ARES_SOCKET_BAD);
+    } while (fdn->grpc_polled_fd->IsFdStillReadableLocked());
+  } else {
+    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
+    // timed out. The pending lookups made on this ev_driver will be cancelled
+    // by the following ares_cancel() and the on_done callbacks will be invoked
+    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
+    // ev_driver will be cleaned up in the follwing
+    // grpc_ares_notify_on_event_locked().
+    ares_cancel(ev_driver->channel);
+  }
+  grpc_ares_notify_on_event_locked(ev_driver);
+  grpc_ares_ev_driver_unref(ev_driver);
+}
+
+static void on_writable_locked(void* arg, grpc_error* error) {
+  fd_node* fdn = static_cast<fd_node*>(arg);
+  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
+  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
+  fdn->writable_registered = false;
+  gpr_log(GPR_DEBUG, "writable on %s", fdn->grpc_polled_fd->GetName());
+  if (error == GRPC_ERROR_NONE) {
+    ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, as);
+  } else {
+    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
+    // timed out. The pending lookups made on this ev_driver will be cancelled
+    // by the following ares_cancel() and the on_done callbacks will be invoked
+    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
+    // ev_driver will be cleaned up in the follwing
+    // grpc_ares_notify_on_event_locked().
+    ares_cancel(ev_driver->channel);
+  }
+  grpc_ares_notify_on_event_locked(ev_driver);
+  grpc_ares_ev_driver_unref(ev_driver);
+}
+
+ares_channel* grpc_ares_ev_driver_get_channel_locked(
+    grpc_ares_ev_driver* ev_driver) {
+  return &ev_driver->channel;
+}
+
+// Get the file descriptors used by the ev_driver's ares channel, register
+// driver_closure with these filedescriptors.
+static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver) {
+  fd_node* new_list = nullptr;
+  if (!ev_driver->shutting_down) {
+    ares_socket_t socks[ARES_GETSOCK_MAXNUM];
+    int socks_bitmask =
+        ares_getsock(ev_driver->channel, socks, ARES_GETSOCK_MAXNUM);
+    for (size_t i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
+      if (ARES_GETSOCK_READABLE(socks_bitmask, i) ||
+          ARES_GETSOCK_WRITABLE(socks_bitmask, i)) {
+        fd_node* fdn = pop_fd_node_locked(&ev_driver->fds, socks[i]);
+        // Create a new fd_node if sock[i] is not in the fd_node list.
+        if (fdn == nullptr) {
+          fdn = static_cast<fd_node*>(gpr_malloc(sizeof(fd_node)));
+          fdn->grpc_polled_fd = grpc_core::NewGrpcPolledFdLocked(
+              socks[i], ev_driver->pollset_set);
+          gpr_log(GPR_DEBUG, "new fd: %s", fdn->grpc_polled_fd->GetName());
+          fdn->ev_driver = ev_driver;
+          fdn->readable_registered = false;
+          fdn->writable_registered = false;
+          fdn->already_shutdown = false;
+          GRPC_CLOSURE_INIT(&fdn->read_closure, on_readable_locked, fdn,
+                            grpc_combiner_scheduler(ev_driver->combiner));
+          GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable_locked, fdn,
+                            grpc_combiner_scheduler(ev_driver->combiner));
+        }
+        fdn->next = new_list;
+        new_list = fdn;
+        // Register read_closure if the socket is readable and read_closure has
+        // not been registered with this socket.
+        if (ARES_GETSOCK_READABLE(socks_bitmask, i) &&
+            !fdn->readable_registered) {
+          grpc_ares_ev_driver_ref(ev_driver);
+          gpr_log(GPR_DEBUG, "notify read on: %s",
+                  fdn->grpc_polled_fd->GetName());
+          fdn->grpc_polled_fd->RegisterForOnReadableLocked(&fdn->read_closure);
+          fdn->readable_registered = true;
+        }
+        // Register write_closure if the socket is writable and write_closure
+        // has not been registered with this socket.
+        if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) &&
+            !fdn->writable_registered) {
+          gpr_log(GPR_DEBUG, "notify write on: %s",
+                  fdn->grpc_polled_fd->GetName());
+          grpc_ares_ev_driver_ref(ev_driver);
+          fdn->grpc_polled_fd->RegisterForOnWriteableLocked(
+              &fdn->write_closure);
+          fdn->writable_registered = true;
+        }
+      }
+    }
+  }
+  // Any remaining fds in ev_driver->fds were not returned by ares_getsock() and
+  // are therefore no longer in use, so they can be shut down and removed from
+  // the list.
+  while (ev_driver->fds != nullptr) {
+    fd_node* cur = ev_driver->fds;
+    ev_driver->fds = ev_driver->fds->next;
+    fd_node_shutdown_locked(cur, "c-ares fd shutdown");
+    if (!cur->readable_registered && !cur->writable_registered) {
+      fd_node_destroy_locked(cur);
+    } else {
+      cur->next = new_list;
+      new_list = cur;
+    }
+  }
+  ev_driver->fds = new_list;
+  // If the ev driver has no working fd, all the tasks are done.
+  if (new_list == nullptr) {
+    ev_driver->working = false;
+    gpr_log(GPR_DEBUG, "ev driver stop working");
+  }
+}
+
+void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver) {
+  if (!ev_driver->working) {
+    ev_driver->working = true;
+    grpc_ares_notify_on_event_locked(ev_driver);
+  }
+}
+
+#endif /* GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET_ARES_EV_DRIVER) */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h
index 27d1511d94..7002c8f95f 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h
@@ -22,6 +22,7 @@
 #include <grpc/support/port_platform.h>
 
 #include <ares.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;
@@ -51,5 +52,40 @@ void grpc_ares_ev_driver_destroy_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);
 
+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
+};
+
+/* Creates a new wrapped fd for the current platform */
+GrpcPolledFd* NewGrpcPolledFdLocked(ares_socket_t as,
+                                    grpc_pollset_set* driver_pollset_set);
+void ConfigureAresChannelLocked(ares_channel* channel);
+
+}  // namespace grpc_core
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_EV_DRIVER_H \
         */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
index b73e979e9f..5db832baf8 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
@@ -36,286 +36,60 @@
 #include "src/core/lib/iomgr/iomgr_internal.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 
-typedef struct fd_node {
-  /** the owner of this fd node */
-  grpc_ares_ev_driver* ev_driver;
-  /** a closure wrapping on_readable_locked, which should be
-     invoked when the grpc_fd in this node becomes readable. */
-  grpc_closure read_closure;
-  /** a closure wrapping on_writable_locked, which should be
-     invoked when the grpc_fd in this node becomes writable. */
-  grpc_closure write_closure;
-  /** next fd node in the list */
-  struct fd_node* next;
-
-  /** the grpc_fd owned by this fd node */
-  grpc_fd* fd;
-  /** if the readable closure has been registered */
-  bool readable_registered;
-  /** if the writable closure has been registered */
-  bool writable_registered;
-  /** if the fd has been shutdown yet from grpc iomgr perspective */
-  bool already_shutdown;
-} fd_node;
-
-struct grpc_ares_ev_driver {
-  /** the ares_channel owned by this event driver */
-  ares_channel channel;
-  /** pollset set for driving the IO events of the channel */
-  grpc_pollset_set* pollset_set;
-  /** refcount of the event driver */
-  gpr_refcount refs;
-
-  /** combiner to synchronize c-ares and I/O callbacks on */
-  grpc_combiner* combiner;
-  /** a list of grpc_fd that this event driver is currently using. */
-  fd_node* fds;
-  /** is this event driver currently working? */
-  bool working;
-  /** is this event driver being shut down */
-  bool shutting_down;
-};
-
-static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver);
-
-static grpc_ares_ev_driver* grpc_ares_ev_driver_ref(
-    grpc_ares_ev_driver* ev_driver) {
-  gpr_log(GPR_DEBUG, "Ref ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
-  gpr_ref(&ev_driver->refs);
-  return ev_driver;
-}
-
-static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver* ev_driver) {
-  gpr_log(GPR_DEBUG, "Unref ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
-  if (gpr_unref(&ev_driver->refs)) {
-    gpr_log(GPR_DEBUG, "destroy ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
-    GPR_ASSERT(ev_driver->fds == nullptr);
-    GRPC_COMBINER_UNREF(ev_driver->combiner, "free ares event driver");
-    ares_destroy(ev_driver->channel);
-    gpr_free(ev_driver);
+namespace grpc_core {
+
+class GrpcPolledFdPosix : public GrpcPolledFd {
+ public:
+  GrpcPolledFdPosix(ares_socket_t as, grpc_pollset_set* driver_pollset_set)
+      : as_(as) {
+    gpr_asprintf(&name_, "c-ares fd: %d", (int)as);
+    fd_ = grpc_fd_create((int)as, name_, false);
+    grpc_pollset_set_add_fd(driver_pollset_set, fd_);
   }
-}
-
-static void fd_node_destroy_locked(fd_node* fdn) {
-  gpr_log(GPR_DEBUG, "delete fd: %d", grpc_fd_wrapped_fd(fdn->fd));
-  GPR_ASSERT(!fdn->readable_registered);
-  GPR_ASSERT(!fdn->writable_registered);
-  GPR_ASSERT(fdn->already_shutdown);
-  /* c-ares library will close the fd inside grpc_fd. This fd may be picked up
-     immediately by another thread, and should not be closed by the following
-     grpc_fd_orphan. */
-  int dummy_release_fd;
-  grpc_fd_orphan(fdn->fd, nullptr, &dummy_release_fd, "c-ares query finished");
-  gpr_free(fdn);
-}
 
-static void fd_node_shutdown_locked(fd_node* fdn, const char* reason) {
-  if (!fdn->already_shutdown) {
-    fdn->already_shutdown = true;
-    grpc_fd_shutdown(fdn->fd, GRPC_ERROR_CREATE_FROM_STATIC_STRING(reason));
+  ~GrpcPolledFdPosix() {
+    gpr_free(name_);
+    /* c-ares library will close the fd inside grpc_fd. This fd may be picked up
+       immediately by another thread, and should not be closed by the following
+       grpc_fd_orphan. */
+    int dummy_release_fd;
+    grpc_fd_orphan(fd_, nullptr, &dummy_release_fd, "c-ares query finished");
   }
-}
 
-grpc_error* grpc_ares_ev_driver_create_locked(grpc_ares_ev_driver** ev_driver,
-                                              grpc_pollset_set* pollset_set,
-                                              grpc_combiner* combiner) {
-  *ev_driver = static_cast<grpc_ares_ev_driver*>(
-      gpr_malloc(sizeof(grpc_ares_ev_driver)));
-  ares_options opts;
-  memset(&opts, 0, sizeof(opts));
-  opts.flags |= ARES_FLAG_STAYOPEN;
-  int status = ares_init_options(&(*ev_driver)->channel, &opts, ARES_OPT_FLAGS);
-  gpr_log(GPR_DEBUG, "grpc_ares_ev_driver_create_locked");
-  if (status != ARES_SUCCESS) {
-    char* err_msg;
-    gpr_asprintf(&err_msg, "Failed to init ares channel. C-ares error: %s",
-                 ares_strerror(status));
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_msg);
-    gpr_free(err_msg);
-    gpr_free(*ev_driver);
-    return err;
+  void RegisterForOnReadableLocked(grpc_closure* read_closure) override {
+    grpc_fd_notify_on_read(fd_, read_closure);
   }
-  (*ev_driver)->combiner = GRPC_COMBINER_REF(combiner, "ares event driver");
-  gpr_ref_init(&(*ev_driver)->refs, 1);
-  (*ev_driver)->pollset_set = pollset_set;
-  (*ev_driver)->fds = nullptr;
-  (*ev_driver)->working = false;
-  (*ev_driver)->shutting_down = false;
-  return GRPC_ERROR_NONE;
-}
 
-void grpc_ares_ev_driver_destroy_locked(grpc_ares_ev_driver* ev_driver) {
-  // We mark the event driver as being shut down. If the event driver
-  // is working, grpc_ares_notify_on_event_locked will shut down the
-  // fds; if it's not working, there are no fds to shut down.
-  ev_driver->shutting_down = true;
-  grpc_ares_ev_driver_unref(ev_driver);
-}
+  void RegisterForOnWriteableLocked(grpc_closure* write_closure) override {
+    grpc_fd_notify_on_write(fd_, write_closure);
+  }
 
-void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver) {
-  ev_driver->shutting_down = true;
-  fd_node* fn = ev_driver->fds;
-  while (fn != nullptr) {
-    fd_node_shutdown_locked(fn, "grpc_ares_ev_driver_shutdown");
-    fn = fn->next;
+  bool IsFdStillReadableLocked() override {
+    size_t bytes_available = 0;
+    return ioctl(grpc_fd_wrapped_fd(fd_), FIONREAD, &bytes_available) == 0 &&
+           bytes_available > 0;
   }
-}
 
-// Search fd in the fd_node list head. This is an O(n) search, the max possible
-// value of n is ARES_GETSOCK_MAXNUM (16). n is typically 1 - 2 in our tests.
-static fd_node* pop_fd_node_locked(fd_node** head, int fd) {
-  fd_node dummy_head;
-  dummy_head.next = *head;
-  fd_node* node = &dummy_head;
-  while (node->next != nullptr) {
-    if (grpc_fd_wrapped_fd(node->next->fd) == fd) {
-      fd_node* ret = node->next;
-      node->next = node->next->next;
-      *head = dummy_head.next;
-      return ret;
-    }
-    node = node->next;
+  void ShutdownLocked(grpc_error* error) override {
+    grpc_fd_shutdown(fd_, error);
   }
-  return nullptr;
-}
 
-/* Check if \a fd is still readable */
-static bool grpc_ares_is_fd_still_readable_locked(
-    grpc_ares_ev_driver* ev_driver, int fd) {
-  size_t bytes_available = 0;
-  return ioctl(fd, FIONREAD, &bytes_available) == 0 && bytes_available > 0;
-}
+  ares_socket_t GetWrappedAresSocketLocked() override { return as_; }
 
-static void on_readable_locked(void* arg, grpc_error* error) {
-  fd_node* fdn = static_cast<fd_node*>(arg);
-  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
-  const int fd = grpc_fd_wrapped_fd(fdn->fd);
-  fdn->readable_registered = false;
-  gpr_log(GPR_DEBUG, "readable on %d", fd);
-  if (error == GRPC_ERROR_NONE) {
-    do {
-      ares_process_fd(ev_driver->channel, fd, ARES_SOCKET_BAD);
-    } while (grpc_ares_is_fd_still_readable_locked(ev_driver, fd));
-  } else {
-    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
-    // timed out. The pending lookups made on this ev_driver will be cancelled
-    // by the following ares_cancel() and the on_done callbacks will be invoked
-    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
-    // ev_driver will be cleaned up in the follwing
-    // grpc_ares_notify_on_event_locked().
-    ares_cancel(ev_driver->channel);
-  }
-  grpc_ares_notify_on_event_locked(ev_driver);
-  grpc_ares_ev_driver_unref(ev_driver);
-}
+  const char* GetName() override { return name_; }
 
-static void on_writable_locked(void* arg, grpc_error* error) {
-  fd_node* fdn = static_cast<fd_node*>(arg);
-  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
-  const int fd = grpc_fd_wrapped_fd(fdn->fd);
-  fdn->writable_registered = false;
-  gpr_log(GPR_DEBUG, "writable on %d", fd);
-  if (error == GRPC_ERROR_NONE) {
-    ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, fd);
-  } else {
-    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
-    // timed out. The pending lookups made on this ev_driver will be cancelled
-    // by the following ares_cancel() and the on_done callbacks will be invoked
-    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
-    // ev_driver will be cleaned up in the follwing
-    // grpc_ares_notify_on_event_locked().
-    ares_cancel(ev_driver->channel);
-  }
-  grpc_ares_notify_on_event_locked(ev_driver);
-  grpc_ares_ev_driver_unref(ev_driver);
-}
+  char* name_;
+  ares_socket_t as_;
+  grpc_fd* fd_;
+};
 
-ares_channel* grpc_ares_ev_driver_get_channel_locked(
-    grpc_ares_ev_driver* ev_driver) {
-  return &ev_driver->channel;
+GrpcPolledFd* NewGrpcPolledFdLocked(ares_socket_t as,
+                                    grpc_pollset_set* driver_pollset_set) {
+  return grpc_core::New<GrpcPolledFdPosix>(as, driver_pollset_set);
 }
 
-// Get the file descriptors used by the ev_driver's ares channel, register
-// driver_closure with these filedescriptors.
-static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver) {
-  fd_node* new_list = nullptr;
-  if (!ev_driver->shutting_down) {
-    ares_socket_t socks[ARES_GETSOCK_MAXNUM];
-    int socks_bitmask =
-        ares_getsock(ev_driver->channel, socks, ARES_GETSOCK_MAXNUM);
-    for (size_t i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
-      if (ARES_GETSOCK_READABLE(socks_bitmask, i) ||
-          ARES_GETSOCK_WRITABLE(socks_bitmask, i)) {
-        fd_node* fdn = pop_fd_node_locked(&ev_driver->fds, socks[i]);
-        // Create a new fd_node if sock[i] is not in the fd_node list.
-        if (fdn == nullptr) {
-          char* fd_name;
-          gpr_asprintf(&fd_name, "ares_ev_driver-%" PRIuPTR, i);
-          fdn = static_cast<fd_node*>(gpr_malloc(sizeof(fd_node)));
-          gpr_log(GPR_DEBUG, "new fd: %d", socks[i]);
-          fdn->fd = grpc_fd_create(socks[i], fd_name, false);
-          fdn->ev_driver = ev_driver;
-          fdn->readable_registered = false;
-          fdn->writable_registered = false;
-          fdn->already_shutdown = false;
-          GRPC_CLOSURE_INIT(&fdn->read_closure, on_readable_locked, fdn,
-                            grpc_combiner_scheduler(ev_driver->combiner));
-          GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable_locked, fdn,
-                            grpc_combiner_scheduler(ev_driver->combiner));
-          grpc_pollset_set_add_fd(ev_driver->pollset_set, fdn->fd);
-          gpr_free(fd_name);
-        }
-        fdn->next = new_list;
-        new_list = fdn;
-        // Register read_closure if the socket is readable and read_closure has
-        // not been registered with this socket.
-        if (ARES_GETSOCK_READABLE(socks_bitmask, i) &&
-            !fdn->readable_registered) {
-          grpc_ares_ev_driver_ref(ev_driver);
-          gpr_log(GPR_DEBUG, "notify read on: %d", grpc_fd_wrapped_fd(fdn->fd));
-          grpc_fd_notify_on_read(fdn->fd, &fdn->read_closure);
-          fdn->readable_registered = true;
-        }
-        // Register write_closure if the socket is writable and write_closure
-        // has not been registered with this socket.
-        if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) &&
-            !fdn->writable_registered) {
-          gpr_log(GPR_DEBUG, "notify write on: %d",
-                  grpc_fd_wrapped_fd(fdn->fd));
-          grpc_ares_ev_driver_ref(ev_driver);
-          grpc_fd_notify_on_write(fdn->fd, &fdn->write_closure);
-          fdn->writable_registered = true;
-        }
-      }
-    }
-  }
-  // Any remaining fds in ev_driver->fds were not returned by ares_getsock() and
-  // are therefore no longer in use, so they can be shut down and removed from
-  // the list.
-  while (ev_driver->fds != nullptr) {
-    fd_node* cur = ev_driver->fds;
-    ev_driver->fds = ev_driver->fds->next;
-    fd_node_shutdown_locked(cur, "c-ares fd shutdown");
-    if (!cur->readable_registered && !cur->writable_registered) {
-      fd_node_destroy_locked(cur);
-    } else {
-      cur->next = new_list;
-      new_list = cur;
-    }
-  }
-  ev_driver->fds = new_list;
-  // If the ev driver has no working fd, all the tasks are done.
-  if (new_list == nullptr) {
-    ev_driver->working = false;
-    gpr_log(GPR_DEBUG, "ev driver stop working");
-  }
-}
+void ConfigureAresChannelLocked(ares_channel* channel) {}
 
-void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver) {
-  if (!ev_driver->working) {
-    ev_driver->working = true;
-    grpc_ares_notify_on_event_locked(ev_driver);
-  }
-}
+}  // namespace grpc_core
 
 #endif /* GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET_ARES_EV_DRIVER) */
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index 5511bf9a32..d7d489c5a4 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -345,6 +345,7 @@ CORE_SOURCE_FILES = [
     'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
     'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
     'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc',
+    'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc',
     'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc',
     'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc',
     'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc',
diff --git a/tools/doxygen/Doxyfile.core.internal b/tools/doxygen/Doxyfile.core.internal
index 589e862b9a..478c417ab3 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -913,6 +913,7 @@ src/core/ext/filters/client_channel/resolver.cc \
 src/core/ext/filters/client_channel/resolver.h \
 src/core/ext/filters/client_channel/resolver/README.md \
 src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc \
+src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc \
 src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h \
 src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc \
 src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc \
diff --git a/tools/run_tests/generated/sources_and_headers.json b/tools/run_tests/generated/sources_and_headers.json
index 4b5f7d51ea..413efa5eac 100644
--- a/tools/run_tests/generated/sources_and_headers.json
+++ b/tools/run_tests/generated/sources_and_headers.json
@@ -10136,6 +10136,7 @@
     "name": "grpc_resolver_dns_ares", 
     "src": [
       "src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc", 
+      "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc", 
       "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h", 
       "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc", 
       "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc",