Restrict httpPayload targets for AWS protocols

The AWS protocols do not currently support http payloads that target
sets, lists, or maps. This adds validators to ensure that such
bindings do not get used.

smithy-aws-traits/src/main/java/software/amazon/smithy/aws/traits/protocols/ProtocolHttpPayloadValidator.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.aws.traits.protocols;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.knowledge.HttpBinding;
+import software.amazon.smithy.model.knowledge.HttpBinding.Location;
+import software.amazon.smithy.model.knowledge.HttpBindingIndex;
+import software.amazon.smithy.model.knowledge.ServiceIndex;
+import software.amazon.smithy.model.knowledge.TopDownIndex;
+import software.amazon.smithy.model.shapes.OperationShape;
+import software.amazon.smithy.model.shapes.ServiceShape;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.shapes.ShapeType;
+import software.amazon.smithy.model.shapes.ToShapeId;
+import software.amazon.smithy.model.traits.Trait;
+import software.amazon.smithy.model.validation.AbstractValidator;
+import software.amazon.smithy.model.validation.ValidationEvent;
+import software.amazon.smithy.utils.SetUtils;
+import software.amazon.smithy.utils.SmithyInternalApi;
+
+/**
+ * Ensures that the http payload trait is only bound to structures, unions,
+ * documents, blobs, or strings for AWS protocols.
+ */
+@SmithyInternalApi
+public final class ProtocolHttpPayloadValidator extends AbstractValidator {
+    private static final Set<ShapeType> VALID_HTTP_PAYLOAD_TYPES = SetUtils.of(
+            ShapeType.STRUCTURE, ShapeType.UNION, ShapeType.DOCUMENT, ShapeType.BLOB, ShapeType.STRING
+    );
+
+    @Override
+    public List<ValidationEvent> validate(Model model) {
+        ServiceIndex serviceIndex = ServiceIndex.of(model);
+        HttpBindingIndex bindingIndex = HttpBindingIndex.of(model);
+        TopDownIndex topDownIndex = TopDownIndex.of(model);
+        return model.shapes(ServiceShape.class)
+                .filter(service -> usesAwsProtocol(service, serviceIndex))
+                .flatMap(service -> validateService(model, service, bindingIndex, topDownIndex).stream())
+                .collect(Collectors.toList());
+    }
+
+    private boolean usesAwsProtocol(ServiceShape service, ServiceIndex index) {
+        for (Trait protocol : index.getProtocols(service).values()) {
+            if (protocol instanceof  AwsProtocolTrait) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private List<ValidationEvent> validateService(
+            Model model,
+            ServiceShape service,
+            HttpBindingIndex bindingIndex,
+            TopDownIndex topDownIndex
+    ) {
+        List<ValidationEvent> events = new ArrayList<>();
+
+        for (OperationShape operation : topDownIndex.getContainedOperations(service)) {
+            List<HttpBinding> requestBindings = bindingIndex.getRequestBindings(operation, Location.PAYLOAD);
+            validateBindings(model, requestBindings).ifPresent(events::add);
+
+            List<HttpBinding> responseBindings = bindingIndex.getResponseBindings(operation, Location.PAYLOAD);
+            validateBindings(model, responseBindings).ifPresent(events::add);
+
+            for (ShapeId error : operation.getErrors()) {
+                List<HttpBinding> errorBindings = bindingIndex.getResponseBindings(error, Location.PAYLOAD);
+                validateBindings(model, errorBindings).ifPresent(events::add);
+            }
+        }
+
+        return events;
+    }
+
+    private Optional<ValidationEvent> validateBindings(Model model, Collection<HttpBinding> payloadBindings) {
+        for (HttpBinding binding : payloadBindings) {
+            if (!payloadBoundToValidType(model, binding.getMember().getTarget())) {
+                return Optional.of(error(binding.getMember(), "AWS Protocols do not support applying the httpPayload "
+                        + "trait to members that target sets, lists, or maps."));
+            }
+        }
+        return Optional.empty();
+    }
+
+    private boolean payloadBoundToValidType(Model model, ToShapeId payloadShape) {
+        return model.getShape(payloadShape.toShapeId())
+                .map(shape -> VALID_HTTP_PAYLOAD_TYPES.contains(shape.getType()))
+                .orElse(false);
+    }
+}

smithy-aws-traits/src/main/resources/META-INF/services/software.amazon.smithy.model.validation.Validator

@@ -3,3 +3,4 @@ software.amazon.smithy.aws.traits.SdkServiceIdValidator
 software.amazon.smithy.aws.traits.clientendpointdiscovery.ClientEndpointDiscoveryValidator
 software.amazon.smithy.aws.traits.protocols.ProtocolHttpValidator
 software.amazon.smithy.aws.traits.EventSourceValidator
+software.amazon.smithy.aws.traits.protocols.ProtocolHttpPayloadValidator

smithy-aws-traits/src/test/resources/software/amazon/smithy/aws/traits/errorfiles/protocols/aws-protocols-do-not-support-list-set-map-payloads.errors

@@ -0,0 +1,3 @@
+[ERROR] smithy.example#InvalidBindingInput$listBinding: AWS Protocols do not support applying the httpPayload trait to members that target sets, lists, or maps. | ProtocolHttpPayload
+[ERROR] smithy.example#InvalidBindingOutput$mapBinding: AWS Protocols do not support applying the httpPayload trait to members that target sets, lists, or maps. | ProtocolHttpPayload
+[ERROR] smithy.example#InvalidBindingError$setBinding: AWS Protocols do not support applying the httpPayload trait to members that target sets, lists, or maps. | ProtocolHttpPayload

smithy-aws-traits/src/test/resources/software/amazon/smithy/aws/traits/errorfiles/protocols/aws-protocols-do-not-support-list-set-map-payloads.smithy

@@ -0,0 +1,50 @@
+// AWS protocols do not currently support applying the http payload trait to
+// sets, lists, or maps.
+
+namespace smithy.example
+
+use aws.protocols#restJson1
+use smithy.api#http
+use smithy.api#httpPayload
+
+@restJson1
+service InvalidExample {
+    version: "2020-12-29",
+    operations: [InvalidBindingOperation],
+}
+
+@http(method: "POST", uri: "/invalid-payload")
+operation InvalidBindingOperation {
+    input: InvalidBindingInput,
+    output: InvalidBindingOutput,
+    errors: [InvalidBindingError],
+}
+
+structure InvalidBindingInput {
+    @httpPayload
+    listBinding: StringList,
+}
+
+structure InvalidBindingOutput {
+    @httpPayload
+    mapBinding: StringMap,
+}
+
+@error("client")
+structure InvalidBindingError {
+    @httpPayload
+    setBinding: StringSet
+}
+
+list StringList {
+    member: String
+}
+
+set StringSet {
+    member: String
+}
+
+map StringMap {
+    key: String,
+    value: String,
+}