Validate that http uri uses ASCII characters

Closes #975

Author: mtdowling

smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/HttpUriFormatValidator.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2022 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.model.validation.validators;
+
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.shapes.Shape;
+import software.amazon.smithy.model.traits.HttpTrait;
+import software.amazon.smithy.model.validation.AbstractValidator;
+import software.amazon.smithy.model.validation.ValidationEvent;
+
+public final class HttpUriFormatValidator extends AbstractValidator {
+    @Override
+    public List<ValidationEvent> validate(Model model) {
+        List<ValidationEvent> events = new ArrayList<>();
+        CharsetEncoder encoder = StandardCharsets.US_ASCII.newEncoder();
+
+        for (Shape shape : model.getShapesWithTrait(HttpTrait.class)) {
+            HttpTrait trait = shape.expectTrait(HttpTrait.class);
+            String uri = trait.getUri().toString();
+            if (!encoder.canEncode(uri)) {
+                events.add(error(shape, trait, "@http trait `uri` is invalid: " + uri));
+            }
+        }
+        return events;
+    }
+}

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

@@ -16,6 +16,7 @@ software.amazon.smithy.model.validation.validators.HttpQueryParamsTraitValidator
 software.amazon.smithy.model.validation.validators.HttpQueryTraitValidator
 software.amazon.smithy.model.validation.validators.HttpResponseCodeSemanticsValidator
 software.amazon.smithy.model.validation.validators.HttpUriConflictValidator
+software.amazon.smithy.model.validation.validators.HttpUriFormatValidator
 software.amazon.smithy.model.validation.validators.JsonNameValidator
 software.amazon.smithy.model.validation.validators.LengthTraitValidator
 software.amazon.smithy.model.validation.validators.MediaTypeValidator

smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/validators/http-uri-format-invalid.errors

@@ -0,0 +1 @@
+[ERROR] ns.foo#SayHello: @http trait `uri` is invalid: /service/小路/💙/طريق | HttpUriFormat

smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/validators/http-uri-format-invalid.json

@@ -0,0 +1,23 @@
+{
+    "smithy": "1.0",
+    "shapes": {
+        "ns.foo#MyService": {
+            "type": "service",
+            "version": "2017-01-17",
+            "operations": [
+                {
+                    "target": "ns.foo#SayHello"
+                }
+            ]
+        },
+        "ns.foo#SayHello": {
+            "type": "operation",
+            "traits": {
+                "smithy.api#http": {
+                    "method": "POST",
+                    "uri": "/service/小路/\uD83D\uDC99/طريق"
+                }
+            }
+        }
+    }
+}