remove content type header from streaming operations if payload is em…

…pty or nil

aws/middleware/content_type.go

@@ -0,0 +1,42 @@
+package middleware
+
+import (
+	"context"
+	"fmt"
+	"github.com/awslabs/smithy-go/middleware"
+	smithyhttp "github.com/awslabs/smithy-go/transport/http"
+)
+
+// removeContentTypeHeader is a build middleware that removes
+// content type header if content-length header is unset or
+// is set to zero,
+type removeContentTypeHeader struct {
+}
+
+// ID the name of the middleware.
+func (m *removeContentTypeHeader) ID() string {
+	return "RemoveContentTypeHeader"
+}
+
+// HandleBuild adds or appends the constructed user agent to the request.
+func (m *removeContentTypeHeader) HandleBuild(ctx context.Context, in middleware.BuildInput, next middleware.BuildHandler) (
+	out middleware.BuildOutput, metadata middleware.Metadata, err error,
+) {
+	req, ok := in.Request.(*smithyhttp.Request)
+	if !ok {
+		return out, metadata, fmt.Errorf("unknown transport type %T", in)
+	}
+
+	// remove contentTypeHeader when content-length is zero
+	if req.ContentLength == 0 {
+		req.Header.Del("content-type")
+	}
+
+	return next.HandleBuild(ctx, in)
+}
+
+// RemoveContentTypeHeader removes content-type header if
+// content length is unset or equal to zero.
+func RemoveContentTypeHeader(stack *middleware.Stack) error {
+	return stack.Build.Add(&removeContentTypeHeader{}, middleware.After)
+}

codegen/smithy-aws-go-codegen/src/main/java/software/amazon/smithy/aws/go/codegen/AwsHttpPresignURLClientGenerator.java

@@ -93,6 +93,10 @@ private static final String addAsUnsignedPayloadName(String operationName) {
         return String.format("add%sPayloadAsUnsigned", operationName);
     }
 
+    private static final Symbol removeContentTypeHeader = SymbolUtils.createValueSymbolBuilder(
+            "RemoveContentTypeHeader", AwsGoDependency.AWS_MIDDLEWARE
+    ).build();
+
     // build pointable symbols
     private static Symbol buildSymbol(String name, boolean exported) {
         if (!exported) {
@@ -255,6 +259,20 @@ private void writePresignOperationFunction(
                                         .getAddOperationMiddlewareFuncName(operationSymbol));
                                 writer.write("c.$L,", CONVERT_TO_PRESIGN_MIDDLEWARE_NAME);
 
+                                // we should remove Content-Type header if input is a stream and
+                                // payload is empty/nil stream.
+                                if (operationInputShape.members().stream().anyMatch(memberShape -> {
+                                    return memberShape.getMemberTrait(model, StreamingTrait.class).isPresent();
+                                })) {
+                                    writer.addUseImports(SmithyGoDependency.SMITHY_MIDDLEWARE);
+                                    writer.addUseImports(AwsGoDependency.AWS_MIDDLEWARE);
+
+                                    writer.openBlock("func(stack *middleware.Stack, options Options) error {", "}," ,
+                                            () -> {
+                                        writer.write("return $T(stack)", removeContentTypeHeader);
+                                    });
+                                }
+
                                 // s3 needs to add a middleware to switch to using unsigned payload .
                                 if (isS3ServiceShape(model, serviceShape)) {
                                     writer.write("$L,", addAsUnsignedPayloadName(operationSymbol.getName()));

service/internal/integrationtest/s3/presign_test.go

@@ -37,10 +37,8 @@ func TestInteg_PresignURL(t *testing.T) {
 			expectedSignedHeader: http.Header{},
 		},
 		"empty-body": {
-			body: bytes.NewReader([]byte("")),
-			expectedSignedHeader: http.Header{
-				"content-type": {"application/octet-stream"},
-			},
+			body:                 bytes.NewReader([]byte("")),
+			expectedSignedHeader: http.Header{},
 		},
 	}