protosanitizer: remove dependency on csi package

The only thing that is needed from the spec is the extension field
definition. It's easier to understand why the code is generic and
going to support future revisions of the spec when using a copy of
that field definition instead of the entire spec package.

Another positive effect is that only a single file needs to be
vendored and compiled by users of the code and not also the more
complex spec.

protosanitizer/protosanitizer.go

@@ -27,7 +27,7 @@ import (
 	"github.com/golang/protobuf/descriptor"
 	"github.com/golang/protobuf/proto"
 	protobuf "github.com/golang/protobuf/protoc-gen-go/descriptor"
-	"github.com/kubernetes-csi/csi-lib-utils/protosanitizer/csi10"
+	protobufdescriptor "github.com/golang/protobuf/protoc-gen-go/descriptor"
 )
 
 // StripSecrets returns a wrapper around the original CSI gRPC message
@@ -151,10 +151,25 @@ func (s *stripSecrets) strip(parsed interface{}, msg interface{}) {
 // isCSI1Secret uses the csi.E_CsiSecret extension from CSI 1.0 to
 // determine whether a field contains secrets.
 func isCSI1Secret(field *protobuf.FieldDescriptorProto) bool {
-	ex, err := proto.GetExtension(field.Options, csi.E_CsiSecret)
+	ex, err := proto.GetExtension(field.Options, e_CsiSecret)
 	return err == nil && ex != nil && *ex.(*bool)
 }
 
+// Copied from the CSI 1.0 spec (https://github.com/container-storage-interface/spec/blob/37e74064635d27c8e33537c863b37ccb1182d4f8/lib/go/csi/csi.pb.go#L4520-L4527)
+// to avoid a package dependency that would prevent usage of this package
+// in repos using an older version of the spec.
+//
+// Future revision of the CSI spec must not change this extensions, otherwise
+// they will break filtering in binaries based on the 1.0 version of the spec.
+var e_CsiSecret = &proto.ExtensionDesc{
+	ExtendedType:  (*protobufdescriptor.FieldOptions)(nil),
+	ExtensionType: (*bool)(nil),
+	Field:         1059,
+	Name:          "csi.v1.csi_secret",
+	Tag:           "varint,1059,opt,name=csi_secret,json=csiSecret",
+	Filename:      "github.com/container-storage-interface/spec/csi.proto",
+}
+
 // isCSI03Secret relies on the naming convention in CSI <= 0.3
 // to determine whether a field contains secrets.
 func isCSI03Secret(field *protobuf.FieldDescriptorProto) bool {

protosanitizer/protosanitizer_test.go

@@ -21,8 +21,8 @@ import (
 	"testing"
 
 	"github.com/golang/protobuf/proto"
-	csi "github.com/kubernetes-csi/csi-lib-utils/protosanitizer/csi10"
 	csi03 "github.com/kubernetes-csi/csi-lib-utils/protosanitizer/test/csi03"
+	csi "github.com/kubernetes-csi/csi-lib-utils/protosanitizer/test/csi10"
 	"github.com/kubernetes-csi/csi-lib-utils/protosanitizer/test/csitest"
 	"github.com/stretchr/testify/assert"
 )