Pseudocode for S3 resolve auth with embedded endpoint provider

Author: SergeyRyabinin

src/aws-cpp-sdk-core/include/smithy/client/AwsSmithyClient.h

@@ -107,6 +107,7 @@ namespace client
     protected:
         void initClient() {
           m_endpointProvider->InitBuiltInParameters(m_clientConfiguration);
+          m_authSchemeResolver->Init(m_clientConfiguration);
         }
 
         inline const char* GetServiceClientName() const override { return m_serviceName.c_str(); }

src/aws-cpp-sdk-core/include/smithy/identity/auth/AuthSchemeResolverBase.h

@@ -29,12 +29,16 @@ namespace smithy {
 
     };
 
-    template<typename ServiceAuthSchemeParametersT = DefaultAuthSchemeResolverParameters>
+    template<typename ServiceAuthSchemeParametersT = DefaultAuthSchemeResolverParameters, typename ClientConfigT = Aws::Client::ClientConfiguration>
     class AuthSchemeResolverBase
     {
     public:
         using ServiceAuthSchemeParameters = ServiceAuthSchemeParametersT;
 
+        virtual void Init(const ClientConfigT& config) {
+          AWS_UNREFERENCED_PARAM(config);
+        };
+
         virtual ~AuthSchemeResolverBase() = default;
         // AuthScheme Resolver returns a list of AuthSchemeOptions for some reason, according to the SRA...
         virtual Aws::Vector<AuthSchemeOption> resolveAuthScheme(const ServiceAuthSchemeParameters& identityProperties) = 0;

src/aws-cpp-sdk-core/include/smithy/identity/auth/built-in/S3AuthResolver.h

@@ -0,0 +1,56 @@
+/**
+* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0.
+ */
+#pragma once
+
+#include <smithy/identity/auth/AuthSchemeResolverBase.h>
+#include <smithy/identity/auth/built-in/SigV4aAuthSchemeOption.h>
+
+// psuedocode draft, must be in S3 package
+namespace smithy {
+    template<>
+    class S3AuthSchemeResolver : public AuthSchemeResolverBase<DefaultAuthSchemeResolverParameters, Aws::S3::S3ClientConfiguration>
+    {
+    public:
+        using ServiceAuthSchemeParameters = DefaultAuthSchemeResolverParameters;
+        virtual ~S3AuthSchemeResolver() = default;
+
+        virtual void Init(const Aws::S3::S3ClientConfiguration& config) {
+          m_endpointProviderForAuth = Aws::MakeShared<S3EndpointProvider>(ALLOCATION_TAG);
+          m_endpointProviderForAuth->InitBuiltInParameters(config);
+          AWS_UNREFERENCED_PARAM(config);
+        };
+
+
+        Aws::Vector<AuthSchemeOption> resolveAuthScheme(const ServiceAuthSchemeParameters& identityProperties) override
+        {
+            // design step 2: skip an additional endpoint resolution call if we know the operation is always the same auth
+            auto operationNameIt = identityProperties.find("OperationName");
+            if (operationNameIt != identityProperties.end()) {
+              auto knownStaticAuthSchemeOption = knownStaticOperations.find(*operationNameIt);
+              if (knownStaticAuthSchemeOption != knownStaticOperations.end()) {
+                return {knownStaticAuthSchemeOption.second};
+              }
+            }
+
+            Aws::Endpoint::EndpointParameters epParams = MapIdentityPropsToEpParams(identityProperties);
+            auto resolveEpOutcome = m_endpointProviderForAuth->ResolveEndpoint(epParams);
+            if (!resolveEpOutcome.IsSuccess()) {
+              TRACE_ERR();
+              return {};
+            }
+
+            Aws::Vector<AuthSchemeOption> authSchemeOptions = BuildAuthSchemeOptionListFromEndpointResolution(resolveEpOutcome.GetResult());
+
+            return authSchemeOptions;
+        }
+    };
+
+    private:
+      std::shared_ptr<S3EndpointProviderBase> m_endpointProviderForAuth;
+
+      // design step 2: skip an additional endpoint resolution call if we know the operation is always the same auth
+      UnorderedMap<String, String> knownStaticOperations;
+
+}