Fixed WinHTTP failfast caused by premature cancellation (#6637)

sdk/core/azure-core/CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Bugs Fixed
 
+Fixed WinHTTP FailFast exception raised when a request is cancelled before the request is actually sent on the wire.
+
 ### Other Changes
 
 ## 1.16.0-beta.1 (2025-06-05)

sdk/core/azure-core/src/http/curl/curl_connection_pool_private.hpp

@@ -28,6 +28,7 @@
 // Define the class name that reads from ConnectionPool private members
 namespace Azure { namespace Core { namespace Test {
   class CurlConnectionPool_connectionPoolTest_Test;
+  class CurlConnectionPool_DISABLED_connectionPoolTest_Test;
   class CurlConnectionPool_uniquePort_Test;
   class CurlConnectionPool_connectionClose_Test;
   class SdkWithLibcurl_globalCleanUp_Test;
@@ -47,6 +48,7 @@ namespace Azure { namespace Core { namespace Http { namespace _detail {
 #if defined(_azure_TESTING_BUILD)
     // Give access to private to this tests class
     friend class Azure::Core::Test::CurlConnectionPool_connectionPoolTest_Test;
+    friend class Azure::Core::Test::CurlConnectionPool_DISABLED_connectionPoolTest_Test;
     friend class Azure::Core::Test::CurlConnectionPool_uniquePort_Test;
     friend class Azure::Core::Test::CurlConnectionPool_connectionClose_Test;
     friend class Azure::Core::Test::SdkWithLibcurl_globalCleanUp_Test;

sdk/core/azure-core/src/http/curl/curl_session_private.hpp

@@ -22,6 +22,7 @@
 // Define the class name that reads from ConnectionPool private members
 namespace Azure { namespace Core { namespace Test {
   class CurlConnectionPool_connectionPoolTest_Test;
+  class CurlConnectionPool_DISABLED_connectionPoolTest_Test;
   class SdkWithLibcurl_globalCleanUp_Test;
 }}} // namespace Azure::Core::Test
 #endif
@@ -44,6 +45,7 @@ namespace Azure { namespace Core { namespace Http {
     // Give access to private to this tests class
     friend class Azure::Core::Test::CurlConnectionPool_connectionPoolTest_Test;
     friend class Azure::Core::Test::SdkWithLibcurl_globalCleanUp_Test;
+    friend class Azure::Core::Test::CurlConnectionPool_DISABLED_connectionPoolTest_Test;
 #endif
   private:
     /**

sdk/core/azure-core/src/http/winhttp/win_http_transport.cpp

@@ -530,8 +530,11 @@ namespace Azure { namespace Core { namespace Http { namespace _detail {
       Azure::Core::Context const& context,
       Azure::DateTime::duration const& pollDuration)
   {
-    // Before doing any work, check to make sure that the context hasn't already been cancelled.
+    //
-    context.ThrowIfCancelled();
+    // Note that we cannot check for cancellation before calling `initiateAction` because it's
+    // possible that the `initiateAction` call is a call to `WinHttpSendRequest` which establishes
+    // the SendContext.
+    //
 
     // By definition, there cannot be any actions outstanding at this point because we have not
     // yet called initiateAction. So it's safe to reset our state here.

sdk/core/azure-core/test/ut/curl_connection_pool_test.cpp

@@ -41,7 +41,11 @@ namespace Azure { namespace Core { namespace Test {
 
 /***********************  Unique Tests for Libcurl   ********************************/
 #if defined(BUILD_CURL_HTTP_TRANSPORT_ADAPTER)
+#if _azure_DISABLE_HTTP_BIN_TESTS
+    TEST(CurlConnectionPool, DISABLED_connectionPoolTest)
+#else
     TEST(CurlConnectionPool, connectionPoolTest)
+#endif
     {
       {
         std::lock_guard<std::mutex> lock(

sdk/core/azure-core/test/ut/transport_adapter_base_test.cpp

@@ -446,7 +446,11 @@ namespace Azure { namespace Core { namespace Test {
     CheckBodyFromBuffer(*response, expectedResponseBodySize);
   }
 
+#if _azure_DISABLE_HTTP_BIN_TESTS
+  TEST_P(TransportAdapter, DISABLED_cancelTransferUpload)
+#else
   TEST_P(TransportAdapter, cancelTransferUpload)
+#endif
   {
     Azure::Core::Url host(AzureSdkHttpbinServer::Put());
     Azure::Core::Context cancelThis;