From 964d679edc32b0f7316cacdb0652477d607f6de5 Mon Sep 17 00:00:00 2001
From: Alexander Polcyn <apolcyn@google.com>
Date: Tue, 21 Aug 2018 08:00:49 -0700
Subject: Resolve ip literals and Windows localhost manually when using c-ares

---
 test/core/iomgr/BUILD                   | 20 ++++++++++++++++-
 test/core/iomgr/resolve_address_test.cc | 40 +++++++++++++++++++++++++++++++--
 2 files changed, 57 insertions(+), 3 deletions(-)

(limited to 'test/core/iomgr')

diff --git a/test/core/iomgr/BUILD b/test/core/iomgr/BUILD
index 675d9e6278..7754bc4970 100644
--- a/test/core/iomgr/BUILD
+++ b/test/core/iomgr/BUILD
@@ -174,9 +174,27 @@ grpc_cc_test(
 )
 
 grpc_cc_test(
-    name = "resolve_address_test",
+    name = "resolve_address_using_ares_resolver_test",
     srcs = ["resolve_address_test.cc"],
     language = "C++",
+    args = [
+        "--resolver=ares",
+    ],
+    deps = [
+        "//:gpr",
+        "//:grpc",
+        "//test/core/util:gpr_test_util",
+        "//test/core/util:grpc_test_util",
+    ],
+)
+
+grpc_cc_test(
+    name = "resolve_address_using_native_resolver_test",
+    srcs = ["resolve_address_test.cc"],
+    language = "C++",
+    args = [
+        "--resolver=native",
+    ],
     deps = [
         "//:gpr",
         "//:grpc",
diff --git a/test/core/iomgr/resolve_address_test.cc b/test/core/iomgr/resolve_address_test.cc
index 2fb831a6a4..52e4840c7c 100644
--- a/test/core/iomgr/resolve_address_test.cc
+++ b/test/core/iomgr/resolve_address_test.cc
@@ -22,8 +22,14 @@
 #include <grpc/support/log.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
+
+#include <string.h>
+
+#include "src/core/lib/gpr/env.h"
+#include "src/core/lib/gpr/string.h"
 #include "src/core/lib/iomgr/executor.h"
 #include "src/core/lib/iomgr/iomgr.h"
+#include "test/core/util/cmdline.h"
 #include "test/core/util/test_config.h"
 
 static gpr_timespec test_deadline(void) {
@@ -240,6 +246,28 @@ static void test_unparseable_hostports(void) {
 }
 
 int main(int argc, char** argv) {
+  // First set the resolver type based off of --resolver
+  const char* resolver_type = nullptr;
+  gpr_cmdline* cl = gpr_cmdline_create("resolve address test");
+  gpr_cmdline_add_string(cl, "resolver", "Resolver type (ares or native)",
+                         &resolver_type);
+  gpr_cmdline_parse(cl, argc, argv);
+  const char* cur_resolver = gpr_getenv("GRPC_DNS_RESOLVER");
+  if (cur_resolver != nullptr && strlen(cur_resolver) != 0) {
+    gpr_log(GPR_INFO, "Warning: overriding resolver setting of %s",
+            cur_resolver);
+  }
+  if (gpr_stricmp(resolver_type, "native") == 0) {
+    gpr_setenv("GRPC_DNS_RESOLVER", "native");
+  } else if (gpr_stricmp(resolver_type, "ares") == 0) {
+#ifndef GRPC_UV
+    gpr_setenv("GRPC_DNS_RESOLVER", "ares");
+#endif
+  } else {
+    gpr_log(GPR_ERROR, "--resolver_type was not set to ares or native");
+    abort();
+  }
+  // Run the test.
   grpc_test_init(argc, argv);
   grpc_init();
   {
@@ -250,10 +278,18 @@ int main(int argc, char** argv) {
     test_missing_default_port();
     test_ipv6_with_port();
     test_ipv6_without_port();
-    test_invalid_ip_addresses();
-    test_unparseable_hostports();
+    if (gpr_stricmp(resolver_type, "ares") != 0) {
+      // These tests can trigger DNS queries to the nearby nameserver
+      // that need to come back in order for the test to succeed.
+      // c-ares is prone to not using the local system caches that the
+      // native getaddrinfo implementations take advantage of, so running
+      // these unit tests under c-ares risks flakiness.
+      test_invalid_ip_addresses();
+      test_unparseable_hostports();
+    }
     grpc_executor_shutdown();
   }
+  gpr_cmdline_destroy(cl);
 
   grpc_shutdown();
   return 0;
-- 
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