fix: use req.Body instead of IOReaderFactory when possible

Changes request RPCs to use req.Body instead of reading into an in memory byte slice via IOReaderFactory. The IOReaderFactory logic is still available for the PATCH field_mask feature.

fixes grpc-ecosystem#3714

Author: leungster

protoc-gen-grpc-gateway/internal/gengateway/template.go

@@ -333,18 +333,26 @@ var (
 	var protoReq {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
 	var metadata runtime.ServerMetadata
 {{if .Body}}
+	{{- $isFieldMask := and $AllowPatchFeature (eq (.HTTPMethod) "PATCH") (.FieldMaskField) (not (eq "*" .GetBodyFieldPath)) }}
+	{{- if $isFieldMask }}
 	newReader, berr := utilities.IOReaderFactory(req.Body)
 	if berr != nil {
 		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", berr)
 	}
+	{{- end}}
 	{{- $protoReq := .Body.AssignableExprPrep "protoReq" .Method.Service.File.GoPkg.Path -}}
 	{{- if ne "" $protoReq }}
 	{{printf "%s" $protoReq }}
 	{{- end}}
+	{{- if not $isFieldMask }}
+	if err := marshaler.NewDecoder(req.Body).Decode(&{{.Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path}}); err != nil && err != io.EOF  {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+	{{end}}
+	{{- if $isFieldMask }}
 	if err := marshaler.NewDecoder(newReader()).Decode(&{{.Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path}}); err != nil && err != io.EOF  {
 		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
 	}
-	{{- if and $AllowPatchFeature (eq (.HTTPMethod) "PATCH") (.FieldMaskField) (not (eq "*" .GetBodyFieldPath)) }}
 	if protoReq.{{.FieldMaskField}} == nil || len(protoReq.{{.FieldMaskField}}.GetPaths()) == 0 {
 			if fieldMask, err := runtime.FieldMaskFromRequestBody(newReader(), protoReq.{{.GetBodyFieldStructName}}); err != nil {
 				return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
@@ -502,18 +510,26 @@ func local_request_{{.Method.Service.GetName}}_{{.Method.GetName}}_{{.Index}}(ct
 	var protoReq {{.Method.RequestType.GoType .Method.Service.File.GoPkg.Path}}
 	var metadata runtime.ServerMetadata
 {{if .Body}}
+	{{- $isFieldMask := and $AllowPatchFeature (eq (.HTTPMethod) "PATCH") (.FieldMaskField) (not (eq "*" .GetBodyFieldPath)) }}
+	{{- if $isFieldMask }}
 	newReader, berr := utilities.IOReaderFactory(req.Body)
 	if berr != nil {
 		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", berr)
 	}
+	{{- end}}
 	{{- $protoReq := .Body.AssignableExprPrep "protoReq" .Method.Service.File.GoPkg.Path -}}
 	{{- if ne "" $protoReq }}
 	{{printf "%s" $protoReq }}
 	{{- end}}
+	{{- if not $isFieldMask }}
+	if err := marshaler.NewDecoder(req.Body).Decode(&{{.Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path}}); err != nil && err != io.EOF  {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+	{{end}}
+	{{- if $isFieldMask }}
 	if err := marshaler.NewDecoder(newReader()).Decode(&{{.Body.AssignableExpr "protoReq" .Method.Service.File.GoPkg.Path}}); err != nil && err != io.EOF  {
 		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
 	}
-	{{- if and $AllowPatchFeature (eq (.HTTPMethod) "PATCH") (.FieldMaskField) (not (eq "*" .GetBodyFieldPath)) }}
 	if protoReq.{{.FieldMaskField}} == nil || len(protoReq.{{.FieldMaskField}}.GetPaths()) == 0 {
 			if fieldMask, err := runtime.FieldMaskFromRequestBody(newReader(), protoReq.{{.GetBodyFieldStructName}}); err != nil {
 				return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)

protoc-gen-grpc-gateway/internal/gengateway/template_test.go

@@ -239,7 +239,7 @@ func TestApplyTemplateRequestWithoutClientStreaming(t *testing.T) {
 		if want := spec.sigWant; !strings.Contains(got, want) {
 			t.Errorf("applyTemplate(%#v) = %s; want to contain %s", file, got, want)
 		}
-		if want := `marshaler.NewDecoder(newReader()).Decode(&protoReq.GetNested().Bool)`; !strings.Contains(got, want) {
+		if want := `marshaler.NewDecoder(req.Body).Decode(&protoReq.GetNested().Bool)`; !strings.Contains(got, want) {
 			t.Errorf("applyTemplate(%#v) = %s; want to contain %s", file, got, want)
 		}
 		if want := `val, ok = pathParams["nested.int32"]`; !strings.Contains(got, want) {
@@ -659,6 +659,9 @@ func TestAllowPatchFeature(t *testing.T) {
 			return
 		}
 		if allowPatchFeature {
+			if want := `marshaler.NewDecoder(newReader()).Decode(&protoReq.Abe)`; !strings.Contains(got, want) {
+				t.Errorf("applyTemplate(%#v) = %s; want to contain %s", file, got, want)
+			}
 			if !strings.Contains(got, want) {
 				t.Errorf("applyTemplate(%#v) = %s; want to contain %s", file, got, want)
 			}