Add client-support for RPC v2 CBOR (#3767)

## Motivation and Context
Follow-up on #2544 to add
client-side support for the protocol

## Description
The client implementation mainly focuses on a sub-section
[Requests](https://smithy.io/2.0/additional-specs/protocols/smithy-rpc-v2.html#requests)
in the spec. To that end, this PR addresses `TODO` for the client to
fill in the blanks and includes additional adjustments/refactoring to
pass client protocol tests.

## Testing
- Existing tests in CI
- Upstream protocol test `rpcv2Cbor`
- Our handwritten protocol test `rpcv2Cbor-extras.smithy`

----

_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._

Author: ysaito1001

CHANGELOG.next.toml

@@ -22,3 +22,9 @@ message = "Fix incorrect redaction of `@sensitive` types in maps and lists."
 references = ["smithy-rs#3765",  "smithy-rs#3757"]
 meta = { "breaking" = false, "tada" = false, "bug" = true, "target" = "client" }
 author = "landonxjames"
+
+[[smithy-rs]]
+message = "Fix client error correction to properly parse structure members that target a `Union` containing that structure recursively."
+references = ["smithy-rs#3767"]
+meta = { "breaking" = false, "tada" = false, "bug" = true, "target" = "client" }
+author = "ysaito1001"

codegen-client-test/build.gradle.kts

@@ -24,6 +24,7 @@ val workingDirUnderBuildDir = "smithyprojections/codegen-client-test/"
 dependencies {
     implementation(project(":codegen-client"))
     implementation("software.amazon.smithy:smithy-aws-protocol-tests:$smithyVersion")
+    implementation("software.amazon.smithy:smithy-protocol-tests:$smithyVersion")
     implementation("software.amazon.smithy:smithy-protocol-test-traits:$smithyVersion")
     implementation("software.amazon.smithy:smithy-aws-traits:$smithyVersion")
 }
@@ -72,6 +73,12 @@ val allCodegenTests = listOf(
     ClientTest("aws.protocoltests.restxml#RestXml", "rest_xml", addMessageToErrors = false),
     ClientTest("aws.protocoltests.query#AwsQuery", "aws_query", addMessageToErrors = false),
     ClientTest("aws.protocoltests.ec2#AwsEc2", "ec2_query", addMessageToErrors = false),
+    ClientTest("smithy.protocoltests.rpcv2Cbor#RpcV2Protocol", "rpcv2Cbor"),
+    ClientTest(
+        "smithy.protocoltests.rpcv2Cbor#RpcV2CborService",
+        "rpcv2Cbor_extras",
+        dependsOn = listOf("rpcv2Cbor-extras.smithy")
+    ),
     ClientTest(
         "aws.protocoltests.restxml.xmlns#RestXmlWithNamespace",
         "rest_xml_namespace",

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/ErrorCorrection.kt

@@ -87,7 +87,18 @@ private fun ClientCodegenContext.errorCorrectedDefault(member: MemberShape): Wri
 
             target is TimestampShape -> instantiator.instantiate(target, Node.from(0)).some()(this)
             target is BlobShape -> instantiator.instantiate(target, Node.from("")).some()(this)
-            target is UnionShape -> rust("Some(#T::Unknown)", targetSymbol)
+            target is UnionShape ->
+                rustTemplate(
+                    "Some(#{unknown})", *preludeScope,
+                    "unknown" to
+                        writable {
+                            if (memberSymbol.isRustBoxed()) {
+                                rust("Box::new(#T::Unknown)", targetSymbol)
+                            } else {
+                                rust("#T::Unknown", targetSymbol)
+                            }
+                        },
+                )
         }
     }
 }

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/protocol/ClientProtocolTestGenerator.kt

@@ -31,6 +31,7 @@ import software.amazon.smithy.rust.codegen.core.smithy.generators.protocol.Proto
 import software.amazon.smithy.rust.codegen.core.smithy.generators.protocol.ServiceShapeId
 import software.amazon.smithy.rust.codegen.core.smithy.generators.protocol.ServiceShapeId.AWS_JSON_10
 import software.amazon.smithy.rust.codegen.core.smithy.generators.protocol.ServiceShapeId.REST_JSON
+import software.amazon.smithy.rust.codegen.core.smithy.generators.protocol.ServiceShapeId.RPC_V2_CBOR
 import software.amazon.smithy.rust.codegen.core.smithy.generators.protocol.TestCase
 import software.amazon.smithy.rust.codegen.core.util.PANIC
 import software.amazon.smithy.rust.codegen.core.util.dq
@@ -78,6 +79,8 @@ class ClientProtocolTestGenerator(
                 FailingTest.RequestTest(AWS_JSON_10, "AwsJson10ClientPopulatesDefaultValuesInInput"),
                 FailingTest.RequestTest(REST_JSON, "RestJsonClientPopulatesDefaultValuesInInput"),
                 FailingTest.RequestTest(REST_JSON, "RestJsonClientUsesExplicitlyProvidedMemberValuesOverDefaults"),
+                FailingTest.RequestTest(RPC_V2_CBOR, "RpcV2CborClientPopulatesDefaultValuesInInput"),
+                FailingTest.RequestTest(RPC_V2_CBOR, "RpcV2CborClientUsesExplicitlyProvidedMemberValuesOverDefaults"),
             )
 
         private val BrokenTests:
@@ -268,6 +271,7 @@ class ClientProtocolTestGenerator(
             """,
             RT.sdkBody(runtimeConfig = rc),
         )
+        val mediaType = testCase.bodyMediaType.orNull()
         rustTemplate(
             """
             use #{DeserializeResponse};
@@ -280,19 +284,19 @@ class ClientProtocolTestGenerator(
             let parsed = de.deserialize_streaming(&mut http_response);
             let parsed = parsed.unwrap_or_else(|| {
                 let http_response = http_response.map(|body| {
-                    #{SdkBody}::from(#{copy_from_slice}(body.bytes().unwrap()))
+                    #{SdkBody}::from(#{copy_from_slice}(&#{decode_body_data}(body.bytes().unwrap(), #{MediaType}::from(${(mediaType ?: "unknown").dq()}))))
                 });
                 de.deserialize_nonstreaming(&http_response)
             });
             """,
             "copy_from_slice" to RT.Bytes.resolve("copy_from_slice"),
-            "SharedResponseDeserializer" to
-                RT.smithyRuntimeApiClient(rc)
-                    .resolve("client::ser_de::SharedResponseDeserializer"),
-            "Operation" to codegenContext.symbolProvider.toSymbol(operationShape),
+            "decode_body_data" to RT.protocolTest(rc, "decode_body_data"),
             "DeserializeResponse" to RT.smithyRuntimeApiClient(rc).resolve("client::ser_de::DeserializeResponse"),
+            "MediaType" to RT.protocolTest(rc, "MediaType"),
+            "Operation" to codegenContext.symbolProvider.toSymbol(operationShape),
             "RuntimePlugin" to RT.runtimePlugin(rc),
             "SdkBody" to RT.sdkBody(rc),
+            "SharedResponseDeserializer" to RT.smithyRuntimeApiClient(rc).resolve("client::ser_de::SharedResponseDeserializer"),
         )
         if (expectedShape.hasTrait<ErrorTrait>()) {
             val errorSymbol = codegenContext.symbolProvider.symbolForOperationError(operationShape)

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/protocol/RequestSerializerGenerator.kt

@@ -19,7 +19,6 @@ import software.amazon.smithy.rust.codegen.core.rustlang.writable
 import software.amazon.smithy.rust.codegen.core.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.core.smithy.RuntimeType.Companion.preludeScope
 import software.amazon.smithy.rust.codegen.core.smithy.generators.protocol.ProtocolPayloadGenerator
-import software.amazon.smithy.rust.codegen.core.smithy.protocols.HttpLocation
 import software.amazon.smithy.rust.codegen.core.smithy.protocols.Protocol
 import software.amazon.smithy.rust.codegen.core.util.dq
 import software.amazon.smithy.rust.codegen.core.util.findStreamingMember
@@ -125,10 +124,8 @@ class RequestSerializerGenerator(
         )
     }
 
-    private fun needsContentLength(operationShape: OperationShape): Boolean {
-        return protocol.httpBindingResolver.requestBindings(operationShape)
-            .any { it.location == HttpLocation.DOCUMENT || it.location == HttpLocation.PAYLOAD }
-    }
+    private fun needsContentLength(operationShape: OperationShape): Boolean =
+        protocol.needsRequestContentLength(operationShape)
 
     private fun createHttpRequest(operationShape: OperationShape): Writable =
         writable {

codegen-core/common-test-models/rpcv2Cbor-extras.smithy

@@ -130,7 +130,8 @@ apply ErrorSerializationOperation @httpMalformedRequestTests([
                 "Content-Type": "application/cbor"
             }
             // An empty CBOR map. We're missing a lot of `@required` members!
-            body: "oA=="
+            body: "oA==",
+            bodyMediaType: "application/cbor"
         },
         response: {
             code: 400,
@@ -149,9 +150,9 @@ apply ErrorSerializationOperation @httpResponseTests([
         id: "OperationOutputSerializationQuestionablyIncludesTypeField",
         documentation: """
         Despite the operation output being a structure shape with the `@error` trait,
-        `__type` field should, in a strict interpretation of the spec, not be included, 
-        because we're not serializing a server error response. However, we do, because 
-        there shouldn't™️ be any harm in doing so, and it greatly simplifies the 
+        `__type` field should, in a strict interpretation of the spec, not be included,
+        because we're not serializing a server error response. However, we do, because
+        there shouldn't™️ be any harm in doing so, and it greatly simplifies the
         code generator. This test just pins this behavior in case we ever modify it.""",
         protocol: rpcv2Cbor,
         code: 200,
@@ -170,6 +171,12 @@ apply SimpleStructOperation @httpResponseTests([
         id: "SimpleStruct",
         protocol: rpcv2Cbor,
         code: 200, // Not used.
+        body: "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",
+        bodyMediaType: "application/cbor",
+        headers: {
+            "smithy-protocol": "rpc-v2-cbor",
+            "Content-Type": "application/cbor"
+        },
         params: {
             blob: "blobby blob",
             boolean: false,
@@ -211,6 +218,12 @@ apply SimpleStructOperation @httpResponseTests([
         id: "SimpleStructWithOptionsSetToNone",
         protocol: rpcv2Cbor,
         code: 200, // Not used.
+        body: "v2xyZXF1aXJlZEJsb2JLYmxvYmJ5IGJsb2JvcmVxdWlyZWRCb29sZWFu9G5yZXF1aXJlZFN0cmluZ3hwVGhlcmUgYXJlIHRocmVlIHRoaW5ncyBhbGwgd2lzZSBtZW4gZmVhcjogdGhlIHNlYSBpbiBzdG9ybSwgYSBuaWdodCB3aXRoIG5vIG1vb24sIGFuZCB0aGUgYW5nZXIgb2YgYSBnZW50bGUgbWFuLmxyZXF1aXJlZEJ5dGUYRW1yZXF1aXJlZFNob3J0GEZvcmVxdWlyZWRJbnRlZ2VyGEdscmVxdWlyZWRMb25nGEhtcmVxdWlyZWRGbG9hdPo/MKPXbnJlcXVpcmVkRG91Ymxl+z/mTQE6kqMFcXJlcXVpcmVkVGltZXN0YW1wwftB1wqrYAAAAGxyZXF1aXJlZEVudW1nRElBTU9ORP8=",
+        bodyMediaType: "application/cbor",
+        headers: {
+            "smithy-protocol": "rpc-v2-cbor",
+            "Content-Type": "application/cbor"
+        },
         params: {
             requiredBlob: "blobby blob",
             requiredBoolean: false,

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/rustlang/CargoDependency.kt

@@ -147,6 +147,14 @@ class InlineDependency(
                 CargoDependency.smithyTypes(runtimeConfig),
             )
 
+        fun cborErrors(runtimeConfig: RuntimeConfig): InlineDependency =
+            forInlineableRustFile(
+                "cbor_errors",
+                CargoDependency.smithyCbor(runtimeConfig),
+                CargoDependency.smithyRuntimeApi(runtimeConfig),
+                CargoDependency.smithyTypes(runtimeConfig),
+            )
+
         fun ec2QueryErrors(runtimeConfig: RuntimeConfig): InlineDependency =
             forInlineableRustFile("ec2_query_errors", CargoDependency.smithyXml(runtimeConfig))
 

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/RuntimeType.kt

@@ -519,6 +519,8 @@ data class RuntimeType(val path: String, val dependency: RustDependency? = null)
         )
 
         // inlinable types
+        fun cborErrors(runtimeConfig: RuntimeConfig) = forInlineDependency(InlineDependency.cborErrors(runtimeConfig))
+
         fun ec2QueryErrors(runtimeConfig: RuntimeConfig) =
             forInlineDependency(InlineDependency.ec2QueryErrors(runtimeConfig))
 

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/Protocol.kt

@@ -78,6 +78,13 @@ interface Protocol {
      * there are no response headers or statuses available to further inform the error parsing.
      */
     fun parseEventStreamErrorMetadata(operationShape: OperationShape): RuntimeType
+
+    /**
+     * Determines whether the `Content-Length` header should be set in an HTTP request.
+     */
+    fun needsRequestContentLength(operationShape: OperationShape): Boolean =
+        httpBindingResolver.requestBindings(operationShape)
+            .any { it.location == HttpLocation.DOCUMENT || it.location == HttpLocation.PAYLOAD }
 }
 
 typealias ProtocolMap<T, C> = Map<ShapeId, ProtocolGeneratorFactory<T, C>>

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/RpcV2Cbor.kt

@@ -7,25 +7,28 @@ package software.amazon.smithy.rust.codegen.core.smithy.protocols
 
 import software.amazon.smithy.codegen.core.CodegenException
 import software.amazon.smithy.model.Model
+import software.amazon.smithy.model.pattern.UriPattern
 import software.amazon.smithy.model.shapes.MemberShape
 import software.amazon.smithy.model.shapes.OperationShape
+import software.amazon.smithy.model.shapes.ServiceShape
 import software.amazon.smithy.model.shapes.ToShapeId
+import software.amazon.smithy.model.traits.HttpTrait
 import software.amazon.smithy.model.traits.TimestampFormatTrait
+import software.amazon.smithy.rust.codegen.core.rustlang.rustTemplate
+import software.amazon.smithy.rust.codegen.core.rustlang.writable
 import software.amazon.smithy.rust.codegen.core.smithy.CodegenContext
 import software.amazon.smithy.rust.codegen.core.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.core.smithy.protocols.parse.CborParserGenerator
 import software.amazon.smithy.rust.codegen.core.smithy.protocols.parse.StructuredDataParserGenerator
 import software.amazon.smithy.rust.codegen.core.smithy.protocols.serialize.CborSerializerGenerator
 import software.amazon.smithy.rust.codegen.core.smithy.protocols.serialize.StructuredDataSerializerGenerator
 import software.amazon.smithy.rust.codegen.core.smithy.transformers.OperationNormalizer
-import software.amazon.smithy.rust.codegen.core.util.PANIC
-import software.amazon.smithy.rust.codegen.core.util.inputShape
 import software.amazon.smithy.rust.codegen.core.util.isStreaming
-import software.amazon.smithy.rust.codegen.core.util.outputShape
 
 class RpcV2CborHttpBindingResolver(
     private val model: Model,
     private val contentTypes: ProtocolContentTypes,
+    private val serviceShape: ServiceShape,
 ) : HttpBindingResolver {
     private fun bindings(shape: ToShapeId): List<HttpBindingDescriptor> {
         val members = shape.let { model.expectShape(it.toShapeId()) }.members()
@@ -47,10 +50,12 @@ class RpcV2CborHttpBindingResolver(
             .toList()
     }
 
-    // TODO(https://github.com/smithy-lang/smithy-rs/issues/3573)
-    //   In the server, this is only used when the protocol actually supports the `@http` trait.
-    //   However, we will have to do this for client support. Perhaps this method deserves a rename.
-    override fun httpTrait(operationShape: OperationShape) = PANIC("RPC v2 does not support the `@http` trait")
+    override fun httpTrait(operationShape: OperationShape): HttpTrait =
+        HttpTrait.builder()
+            .code(200)
+            .method("POST")
+            .uri(UriPattern.parse("/service/${serviceShape.id.name}/operation/${operationShape.id.name}"))
+            .build()
 
     override fun requestBindings(operationShape: OperationShape) = bindings(operationShape.inputShape)
 
@@ -87,6 +92,8 @@ class RpcV2CborHttpBindingResolver(
 }
 
 open class RpcV2Cbor(val codegenContext: CodegenContext) : Protocol {
+    private val runtimeConfig = codegenContext.runtimeConfig
+
     override val httpBindingResolver: HttpBindingResolver =
         RpcV2CborHttpBindingResolver(
             codegenContext.model,
@@ -96,26 +103,50 @@ open class RpcV2Cbor(val codegenContext: CodegenContext) : Protocol {
                 eventStreamContentType = "application/vnd.amazon.eventstream",
                 eventStreamMessageContentType = "application/cbor",
             ),
+            codegenContext.serviceShape,
         )
 
     // Note that [CborParserGenerator] and [CborSerializerGenerator] automatically (de)serialize timestamps
     // using floating point seconds from the epoch.
     override val defaultTimestampFormat: TimestampFormatTrait.Format = TimestampFormatTrait.Format.EPOCH_SECONDS
 
+    override fun additionalRequestHeaders(operationShape: OperationShape): List<Pair<String, String>> =
+        listOf("smithy-protocol" to "rpc-v2-cbor")
+
     override fun additionalResponseHeaders(operationShape: OperationShape): List<Pair<String, String>> =
         listOf("smithy-protocol" to "rpc-v2-cbor")
 
     override fun structuredDataParser(): StructuredDataParserGenerator =
-        CborParserGenerator(codegenContext, httpBindingResolver)
+        CborParserGenerator(
+            codegenContext, httpBindingResolver,
+            handleNullForNonSparseCollection = { collectionName: String ->
+                writable {
+                    // The client should drop a null value in a dense collection, see
+                    // https://github.com/smithy-lang/smithy/blob/6466fe77c65b8a17b219f0b0a60c767915205f95/smithy-protocol-tests/model/rpcv2Cbor/cbor-maps.smithy#L158
+                    rustTemplate(
+                        """
+                        decoder.null()?;
+                        return #{Ok}($collectionName)
+                        """,
+                        *RuntimeType.preludeScope,
+                    )
+                }
+            },
+        )
 
     override fun structuredDataSerializer(): StructuredDataSerializerGenerator =
         CborSerializerGenerator(codegenContext, httpBindingResolver)
 
-    // TODO(https://github.com/smithy-lang/smithy-rs/issues/3573)
     override fun parseHttpErrorMetadata(operationShape: OperationShape): RuntimeType =
-        TODO("rpcv2Cbor client support has not yet been implemented")
+        RuntimeType.cborErrors(runtimeConfig).resolve("parse_error_metadata")
 
     // TODO(https://github.com/smithy-lang/smithy-rs/issues/3573)
     override fun parseEventStreamErrorMetadata(operationShape: OperationShape): RuntimeType =
         TODO("rpcv2Cbor event streams have not yet been implemented")
+
+    // Unlike other protocols, the `rpcv2Cbor` protocol requires that `Content-Length` is always set
+    // unless there is no input or if the operation is an event stream, see
+    // https://github.com/smithy-lang/smithy/blob/6466fe77c65b8a17b219f0b0a60c767915205f95/smithy-protocol-tests/model/rpcv2Cbor/empty-input-output.smithy#L106
+    // TODO(https://github.com/smithy-lang/smithy-rs/issues/3772): Do not set `Content-Length` for event stream operations
+    override fun needsRequestContentLength(operationShape: OperationShape) = operationShape.input.isPresent
 }