rpc: install custom proto codec

This change enables future upgrades of google.golang.org/grpc.

Recent changes to google.golang.org/grpc have changed the default
proto codec such that it is incompatible with gogoproto:

grpc/grpc-go#3958

While `proto.Marshal` does do a check for the Marshal/Unmarshal it
appears to do this through reflection methods that will panic on
fields using gogoproto.nullable.

To avoid this, we install a proto codec that does an interface check
before dispatching to proto.Marshal/proto.Unmarshal.

Note that I haven't replicated the protobuffer caching that previously
existed in google.golang.org/grpc. The referenced change claims
removing the caching may be a small performance win; however, they
also removed the typecheck that we need to do, so it is unclear.

Fixes cockroachdb#60531

Release note: None

pkg/rpc/BUILD.bazel

@@ -9,6 +9,7 @@ go_library(
         "auth_tenant.go",
         "breaker.go",
         "clock_offset.go",
+        "codec.go",
         "connection_class.go",
         "context.go",
         "context_testutils.go",
@@ -39,6 +40,7 @@ go_library(
         "//pkg/util/log/severity",
         "//pkg/util/metric",
         "//pkg/util/netutil",
+        "//pkg/util/protoutil",
         "//pkg/util/stop",
         "//pkg/util/syncutil",
         "//pkg/util/timeutil",
@@ -49,6 +51,7 @@ go_library(
         "@com_github_cockroachdb_errors//:errors",
         "@com_github_cockroachdb_logtags//:logtags",
         "@com_github_facebookgo_clock//:clock",
+        "@com_github_gogo_protobuf//proto",
         "@com_github_golang_snappy//:snappy",
         "@com_github_montanaflynn_stats//:stats",
         "@com_github_vividcortex_ewma//:ewma",
@@ -57,7 +60,6 @@ go_library(
         "@org_golang_google_grpc//codes",
         "@org_golang_google_grpc//credentials",
         "@org_golang_google_grpc//encoding",
-        "@org_golang_google_grpc//encoding/proto",
         "@org_golang_google_grpc//keepalive",
         "@org_golang_google_grpc//metadata",
         "@org_golang_google_grpc//peer",

pkg/rpc/codec.go

@@ -0,0 +1,41 @@
+// Copyright 2020 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package rpc
+
+import (
+	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
+	"github.com/gogo/protobuf/proto"
+	"google.golang.org/grpc/encoding"
+)
+
+const name = "proto"
+
+type codec struct{}
+
+var _ encoding.Codec = codec{}
+
+func (codec) Marshal(v interface{}) ([]byte, error) {
+	if pm, ok := v.(proto.Marshaler); ok {
+		return pm.Marshal()
+	}
+	return protoutil.Marshal(v.(protoutil.Message))
+}
+
+func (codec) Unmarshal(data []byte, v interface{}) error {
+	if pm, ok := v.(proto.Unmarshaler); ok {
+		return pm.Unmarshal(data)
+	}
+	return protoutil.Unmarshal(data, v.(protoutil.Message))
+}
+
+func (codec) Name() string {
+	return name
+}

pkg/rpc/context.go

@@ -46,7 +46,6 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/encoding"
-	encodingproto "google.golang.org/grpc/encoding/proto"
 	"google.golang.org/grpc/metadata"
 	grpcstatus "google.golang.org/grpc/status"
 )
@@ -794,8 +793,7 @@ func (c growStackCodec) Unmarshal(data []byte, v interface{}) error {
 // Install the growStackCodec over the default proto codec in order to grow the
 // stack for BatchRequest RPCs prior to unmarshaling.
 func init() {
-	protoCodec := encoding.GetCodec(encodingproto.Name)
-	encoding.RegisterCodec(growStackCodec{Codec: protoCodec})
+	encoding.RegisterCodec(growStackCodec{Codec: codec{}})
 }
 
 // onlyOnceDialer implements the grpc.WithDialer interface but only

pkg/testutils/lint/lint_test.go

@@ -964,6 +964,7 @@ func TestLint(t *testing.T) {
 			":!sql/*.pb.go",
 			":!util/protoutil/marshal.go",
 			":!util/protoutil/marshaler.go",
+			":!rpc/codec.go",
 			":!settings/settings_test.go",
 			":!sql/types/types_jsonpb.go",
 			":!sql/schemachanger/scbuild/builder_test.go",
@@ -1007,6 +1008,7 @@ func TestLint(t *testing.T) {
 			":!util/protoutil/marshal.go",
 			":!util/protoutil/marshaler.go",
 			":!util/encoding/encoding.go",
+			":!rpc/codec.go",
 			":!util/hlc/timestamp.go",
 			":!sql/types/types_jsonpb.go",
 		)