support connection close header (#2672)

sdk/core/azure-core/CHANGELOG.md

@@ -3,12 +3,15 @@
 ## 1.2.0-beta.1 (Unreleased)
 
 ### Features Added
-- Added `Azure::Core::IO::ProgressBodyStream` type that wraps an existing BodyStream based type stream and reports progress via callback when the stream position is updated. 
+
+- Added `Azure::Core::IO::ProgressBodyStream` type that wraps an existing BodyStream based type stream and reports progress via callback when the stream position is updated.
 
 ### Breaking Changes
 
 ### Bugs Fixed
 
+- [2647](https://github.com/Azure/azure-sdk-for-cpp/issues/2647) Make the curl transport adapter to check the connection close header.
+
 ### Other Changes
 
 ## 1.1.0 (2021-07-02)

sdk/core/azure-core/src/http/curl/curl.cpp

@@ -714,7 +714,20 @@ void CurlSession::ReadStatusLineAndHeadersFromRawResponse(
   }
 
   // headers are already lowerCase at this point
-  auto headers = this->m_response->GetHeaders();
+  auto const& headers = this->m_response->GetHeaders();
+
+  // Check if server has return the connection header. This header can be used to stop re-using the
+  // connection. The `Iot Edge Blob Storage Module` is known to return this after some time re-using
+  // the same http secured channel.
+  auto connectionHeader = headers.find("connection");
+  if (connectionHeader != headers.end())
+  {
+    if (connectionHeader->second == "close")
+    {
+      // Use connection shut-down so it won't be moved it back to the connection pool.
+      m_connection->Shutdown();
+    }
+  }
 
   auto isContentLengthHeaderInResponse = headers.find("content-length");
   if (isContentLengthHeaderInResponse != headers.end())

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

@@ -29,6 +29,7 @@
 namespace Azure { namespace Core { namespace Test {
   class CurlConnectionPool_connectionPoolTest_Test;
   class CurlConnectionPool_uniquePort_Test;
+  class CurlConnectionPool_connectionClose_Test;
 }}} // namespace Azure::Core::Test
 #endif
 
@@ -46,6 +47,7 @@ namespace Azure { namespace Core { namespace Http { namespace _detail {
     // Give access to private to this tests class
     friend class Azure::Core::Test::CurlConnectionPool_connectionPoolTest_Test;
     friend class Azure::Core::Test::CurlConnectionPool_uniquePort_Test;
+    friend class Azure::Core::Test::CurlConnectionPool_connectionClose_Test;
 #endif
 
   public:

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

@@ -554,5 +554,45 @@ namespace Azure { namespace Core { namespace Test {
       }
     }
 
+    TEST(CurlConnectionPool, connectionClose)
+    {
+      /// When getting the header connection: close from an HTTP response, the connection should not
+      /// be moved back to the pool.
+      {
+        std::lock_guard<std::mutex> lock(
+            CurlConnectionPool::g_curlConnectionPool.ConnectionPoolMutex);
+        CurlConnectionPool::g_curlConnectionPool.ConnectionPoolIndex.clear();
+        // Make sure there are nothing in the pool
+        EXPECT_EQ(CurlConnectionPool::g_curlConnectionPool.ConnectionPoolIndex.size(), 0);
+      }
+
+      // Use the same request for all connections.
+      Azure::Core::Http::Request req(
+          Azure::Core::Http::HttpMethod::Get, Azure::Core::Url(AzureSdkHttpbinServer::Headers()));
+      // Server will return this header back
+      req.SetHeader("connection", "close");
+
+      {
+        // Create a pipeline to send the request and dispose after it.
+        Azure::Core::Http::_internal::HttpPipeline pipeline({}, "test", "test", {}, {});
+        auto response = pipeline.Send(req, Azure::Core::Context::ApplicationContext);
+        EXPECT_PRED2(
+            [](Azure::Core::Http::HttpStatusCode a, Azure::Core::Http::HttpStatusCode b) {
+              return a == b;
+            },
+            response->GetStatusCode(),
+            Azure::Core::Http::HttpStatusCode::Ok);
+      }
+
+      // Check that after the connection is gone, it is moved back to the pool
+      {
+        std::lock_guard<std::mutex> lock(
+            CurlConnectionPool::g_curlConnectionPool.ConnectionPoolMutex);
+        EXPECT_EQ(
+            Azure::Core::Http::_detail::CurlConnectionPool::g_curlConnectionPool.ConnectionPoolIndex
+                .size(),
+            0);
+      }
+    }
 #endif
 }}} // namespace Azure::Core::Test

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

@@ -31,6 +31,11 @@ namespace Azure { namespace Core { namespace Test {
       return std::string(_detail::AzureSdkHttpbinServerSchema) + "://"
           + std::string(_detail::AzureSdkHttpbinServer) + "/get";
     }
+    inline static std::string Headers()
+    {
+      return std::string(_detail::AzureSdkHttpbinServerSchema) + "://"
+          + std::string(_detail::AzureSdkHttpbinServer) + "/headers";
+    }
     inline static std::string WithPort()
     {
       return std::string(_detail::AzureSdkHttpbinServerSchema) + "://"