Keep active curl handles out of in-transfer state callbacks

Copilot comment 4114543078: sample listeners in examples/cpp/SampleCpp/DebugCallback.cpp:79-86 and examples/cpp/MacProxy/HttpEventListener.cpp:38-45 set options on non-null handles. OnSending on curl 7.80+ now passes null while OnConnecting retains its pre-transfer handle; legacy timing and handle access stay unchanged.

Files changed: lib/http/HttpClient_Curl.hpp, lib/include/public/IHttpClient.hpp, tests/unittests/HttpClientCurlTests.cpp. Document callback handle availability and assert both runtime paths in loopback tests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 5fa346e8-a5c8-4324-8144-a4a867cb146e

Author: bmehta001

lib/http/HttpClient_Curl.hpp

@@ -170,7 +170,10 @@ class CurlHttpOperation {
         if (m_callback != nullptr)
         {
             HookScope callbackScope(m_callbackHooks);
-            m_callback->OnHttpStateEvent(type, static_cast<void*>(curl), 0);
+            // OnSending runs inside curl_easy_perform with the prereq callback.
+            // Do not expose a handle observers could mutate during that transfer.
+            void* handle = (m_usePrereqCallback && type == OnSending) ? nullptr : static_cast<void*>(curl);
+            m_callback->OnHttpStateEvent(type, handle, 0);
         }
     }
 

lib/include/public/IHttpClient.hpp

@@ -500,7 +500,9 @@ namespace MAT_NS_BEGIN
         ///
         /// </summary>
         /// <param name="state">HttpStateEvent - see diagram</param>
-        /// <param name="data">HTTP client implementation-specific data structure (optional)</param>
+        /// <param name="data">HTTP client implementation-specific data structure (optional).
+        /// On curl 7.80+ the OnSending event runs within a libcurl transfer and does not
+        /// expose its active handle; configure curl options from OnConnecting instead.</param>
         /// <param name="size">HTTP client implementation-specific data structure size (optional)</param>
         virtual void OnHttpStateEvent(HttpStateEvent state, void* data = nullptr, size_t size = 0)
         {

tests/unittests/HttpClientCurlTests.cpp

@@ -188,11 +188,13 @@ TEST_F(HttpClientCurlHeaderTests, CapturesResponseHeadersAndBody)
     struct StateCallback : public IHttpResponseCallback
     {
         std::vector<HttpStateEvent> states;
+        std::vector<void*> handles;
 
         void OnHttpResponse(IHttpResponse* response) override { delete response; }
-        void OnHttpStateEvent(HttpStateEvent state, void*, size_t) override
+        void OnHttpStateEvent(HttpStateEvent state, void* handle, size_t) override
         {
             states.push_back(state);
+            handles.push_back(handle);
         }
     } callback;
 
@@ -212,6 +214,9 @@ TEST_F(HttpClientCurlHeaderTests, CapturesResponseHeadersAndBody)
     EXPECT_EQ(responseHeaders.at("X-MAT-Test"), "header-value");
     EXPECT_EQ(std::string(responseBody.begin(), responseBody.end()), "body-value");
     EXPECT_EQ(callback.states, (std::vector<HttpStateEvent>{OnCreated, OnConnecting, OnSending, OnResponse}));
+    ASSERT_EQ(callback.handles.size(), 4u);
+    EXPECT_EQ(callback.handles[1], operation.GetHandle());
+    EXPECT_EQ(callback.handles[2], UsesPrereqCallback() ? nullptr : operation.GetHandle());
     EXPECT_EQ(m_server.acceptedConnections(), UsesPrereqCallback() ? 1u : 2u);
 }