Revert "Merge pull request #16158 from apolcyn/revert_windows_breakage"

This reverts commit d9e8f86675cf923714b3ead4b06087e14a88c08c, reversing
changes made to 04847aeb1e62bc528d88fa3c47daa24a4cf629b3.

10 files changed, 165 insertions, 12 deletions

diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
index f4f6444c5f..7050e82121 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
@@ -23,7 +23,6 @@
 #include <limits.h>
 #include <stdio.h>
 #include <string.h>
-#include <unistd.h>
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/string_util.h>
@@ -142,8 +141,8 @@ AresDnsResolver::AresDnsResolver(const ResolverArgs& args)
   channel_args_ = grpc_channel_args_copy(args.args);
   const grpc_arg* arg = grpc_channel_args_find(
       channel_args_, GRPC_ARG_SERVICE_CONFIG_DISABLE_RESOLUTION);
-  request_service_config_ = !grpc_channel_arg_get_integer(
-      arg, (grpc_integer_options){false, false, true});
+  grpc_integer_options integer_options = {false, false, true};
+  request_service_config_ = !grpc_channel_arg_get_integer(arg, integer_options);
   arg = grpc_channel_args_find(channel_args_,
                                GRPC_ARG_DNS_MIN_TIME_BETWEEN_RESOLUTIONS_MS);
   min_time_between_resolutions_ =
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
index c886795608..0068d0d5f4 100644
--- 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
@@ -18,11 +18,10 @@
 #include <grpc/support/port_platform.h>
 
 #include "src/core/lib/iomgr/port.h"
-#if GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET_ARES_EV_DRIVER)
+#if GRPC_ARES == 1 && !defined(GRPC_UV)
 
 #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"
 
@@ -32,7 +31,6 @@
 #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"
 
@@ -314,4 +312,4 @@ void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver) {
   }
 }
 
-#endif /* GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET_ARES_EV_DRIVER) */
+#endif /* GRPC_ARES == 1 && !defined(GRPC_UV) */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc
new file mode 100644
index 0000000000..5d65ae3ab3
--- /dev/null
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc
@@ -0,0 +1,59 @@
+/*
+ *
+ * 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(GPR_WINDOWS)
+
+#include <ares.h>
+#include <string.h>
+#include "src/core/lib/gprpp/memory.h"
+
+#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h"
+
+namespace grpc_core {
+
+/* TODO: fill in the body of GrpcPolledFdWindows to enable c-ares on Windows.
+   This dummy implementation only allows grpc to compile on windows with
+   GRPC_ARES=1. */
+class GrpcPolledFdWindows : public GrpcPolledFd {
+ public:
+  GrpcPolledFdWindows() { abort(); }
+  ~GrpcPolledFdWindows() { abort(); }
+  void RegisterForOnReadableLocked(grpc_closure* read_closure) override {
+    abort();
+  }
+  void RegisterForOnWriteableLocked(grpc_closure* write_closure) override {
+    abort();
+  }
+  bool IsFdStillReadableLocked() override { abort(); }
+  void ShutdownLocked(grpc_error* error) override { abort(); }
+  ares_socket_t GetWrappedAresSocketLocked() override { abort(); }
+  const char* GetName() override { abort(); }
+};
+
+GrpcPolledFd* NewGrpcPolledFdLocked(ares_socket_t as,
+                                    grpc_pollset_set* driver_pollset_set) {
+  return nullptr;
+}
+
+void ConfigureAresChannelLocked(ares_channel* channel) { abort(); }
+
+}  // namespace grpc_core
+
+#endif /* GRPC_ARES == 1 && defined(GPR_WINDOWS) */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
index 497ad998af..b3d6437e9a 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
@@ -22,7 +22,6 @@
 
 #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
 #include "src/core/lib/iomgr/sockaddr.h"
-#include "src/core/lib/iomgr/socket_utils_posix.h"
 
 #include <string.h>
 #include <sys/types.h>
@@ -215,7 +214,7 @@ static void on_hostbyname_done_locked(void* arg, int status, int timeouts,
           memset(&addr, 0, addr_len);
           memcpy(&addr.sin6_addr, hostent->h_addr_list[i - prev_naddr],
                  sizeof(struct in6_addr));
-          addr.sin6_family = static_cast<sa_family_t>(hostent->h_addrtype);
+          addr.sin6_family = static_cast<unsigned char>(hostent->h_addrtype);
           addr.sin6_port = hr->port;
           grpc_lb_addresses_set_address(
               *lb_addresses, i, &addr, addr_len,
@@ -236,7 +235,7 @@ static void on_hostbyname_done_locked(void* arg, int status, int timeouts,
           memset(&addr, 0, addr_len);
           memcpy(&addr.sin_addr, hostent->h_addr_list[i - prev_naddr],
                  sizeof(struct in_addr));
-          addr.sin_family = static_cast<sa_family_t>(hostent->h_addrtype);
+          addr.sin_family = static_cast<unsigned char>(hostent->h_addrtype);
           addr.sin_port = hr->port;
           grpc_lb_addresses_set_address(
               *lb_addresses, i, &addr, addr_len,
@@ -281,7 +280,7 @@ static void on_srv_query_done_locked(void* arg, int status, int timeouts,
           grpc_ares_ev_driver_get_channel_locked(r->ev_driver);
       for (struct ares_srv_reply* srv_it = reply; srv_it != nullptr;
            srv_it = srv_it->next) {
-        if (grpc_ipv6_loopback_available()) {
+        if (grpc_ares_query_ipv6()) {
           grpc_ares_hostbyname_request* hr = create_hostbyname_request_locked(
               r, srv_it->host, htons(srv_it->port), true /* is_balancer */);
           ares_gethostbyname(*channel, hr->host, AF_INET6,
@@ -452,7 +451,7 @@ static grpc_ares_request* grpc_dns_lookup_ares_locked_impl(
     }
   }
   r->pending_queries = 1;
-  if (grpc_ipv6_loopback_available()) {
+  if (grpc_ares_query_ipv6()) {
     hr = create_hostbyname_request_locked(r, host, strhtons(port),
                                           false /* is_balancer */);
     ares_gethostbyname(*channel, hr->host, AF_INET6, on_hostbyname_done_locked,
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h
index ce26f5d524..17eaa7ccf0 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h
@@ -70,6 +70,10 @@ void grpc_ares_cleanup(void);
  * and destroys the grpc_ares_request */
 void grpc_ares_complete_request_locked(grpc_ares_request* request);
 
+/* Indicates whether or not AAAA queries should be attempted. */
+/* E.g., return false if ipv6 is known to not be available. */
+bool grpc_ares_query_ipv6();
+
 /* Exposed only for testing */
 void grpc_cares_wrapper_test_only_address_sorting_sort(
     grpc_lb_addresses* lb_addrs);
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc
new file mode 100644
index 0000000000..23c0fec74f
--- /dev/null
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc
@@ -0,0 +1,29 @@
+/*
+ *
+ * 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 "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
+#include "src/core/lib/iomgr/socket_utils_posix.h"
+
+bool grpc_ares_query_ipv6() { return grpc_ipv6_loopback_available(); }
+
+#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_wrapper_windows.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc
new file mode 100644
index 0000000000..ee827e284e
--- /dev/null
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc
@@ -0,0 +1,29 @@
+/*
+ *
+ * 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(GPR_WINDOWS)
+
+#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
+#include "src/core/lib/iomgr/socket_windows.h"
+
+bool grpc_ares_query_ipv6() { return grpc_ipv6_loopback_available(); }
+
+#endif /* GRPC_ARES == 1 && defined(GPR_WINDOWS) */
diff --git a/src/core/lib/iomgr/socket_windows.cc b/src/core/lib/iomgr/socket_windows.cc
index 2e23409582..4ad31cb35d 100644
--- a/src/core/lib/iomgr/socket_windows.cc
+++ b/src/core/lib/iomgr/socket_windows.cc
@@ -36,6 +36,7 @@
 #include "src/core/lib/iomgr/iomgr_internal.h"
 #include "src/core/lib/iomgr/pollset.h"
 #include "src/core/lib/iomgr/pollset_windows.h"
+#include "src/core/lib/iomgr/sockaddr_windows.h"
 #include "src/core/lib/iomgr/socket_windows.h"
 
 grpc_winsocket* grpc_winsocket_create(SOCKET socket, const char* name) {
@@ -148,4 +149,32 @@ void grpc_socket_become_ready(grpc_winsocket* socket,
   if (should_destroy) destroy(socket);
 }
 
+static gpr_once g_probe_ipv6_once = GPR_ONCE_INIT;
+static bool g_ipv6_loopback_available = false;
+
+static void probe_ipv6_once(void) {
+  SOCKET s = socket(AF_INET6, SOCK_STREAM, 0);
+  g_ipv6_loopback_available = 0;
+  if (s == INVALID_SOCKET) {
+    gpr_log(GPR_INFO, "Disabling AF_INET6 sockets because socket() failed.");
+  } else {
+    grpc_sockaddr_in6 addr;
+    memset(&addr, 0, sizeof(addr));
+    addr.sin6_family = AF_INET6;
+    addr.sin6_addr.s6_addr[15] = 1; /* [::1]:0 */
+    if (bind(s, reinterpret_cast<grpc_sockaddr*>(&addr), sizeof(addr)) == 0) {
+      g_ipv6_loopback_available = 1;
+    } else {
+      gpr_log(GPR_INFO,
+              "Disabling AF_INET6 sockets because ::1 is not available.");
+    }
+    closesocket(s);
+  }
+}
+
+int grpc_ipv6_loopback_available(void) {
+  gpr_once_init(&g_probe_ipv6_once, probe_ipv6_once);
+  return g_ipv6_loopback_available;
+}
+
 #endif /* GRPC_WINSOCK_SOCKET */
diff --git a/src/core/lib/iomgr/socket_windows.h b/src/core/lib/iomgr/socket_windows.h
index 7bd01eded5..b09b9da562 100644
--- a/src/core/lib/iomgr/socket_windows.h
+++ b/src/core/lib/iomgr/socket_windows.h
@@ -108,6 +108,10 @@ void grpc_socket_notify_on_read(grpc_winsocket* winsocket,
 void grpc_socket_become_ready(grpc_winsocket* winsocket,
                               grpc_winsocket_callback_info* ci);
 
+/* Returns true if this system can create AF_INET6 sockets bound to ::1.
+   The value is probed once, and cached for the life of the process. */
+int grpc_ipv6_loopback_available(void);
+
 #endif
 
 #endif /* GRPC_CORE_LIB_IOMGR_SOCKET_WINDOWS_H */
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index 49185cc648..d6efb49750 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -354,8 +354,11 @@ CORE_SOURCE_FILES = [
     '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_ev_driver_windows.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',
+    'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc',
+    'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc',
     'src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.cc',
     'src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.cc',
     'src/cpp/ext/filters/census/grpc_context.cc',