lnd: add aux data parser

This commit adds an optional data parser that can inspect and in-place
format custom data of certain RPC messages.

config_builder.go

@@ -173,6 +173,10 @@ type AuxComponents struct {
  // AuxSigner is an optional signer that can be used to sign auxiliary
  // leaves for certain custom channel types.
  AuxSigner fn.Option[lnwallet.AuxSigner]
+
+ // AuxDataParser is an optional data parser that can be used to parse
+ // auxiliary data for certain custom channel types.
+ AuxDataParser fn.Option[AuxDataParser]
 }
 
 // DefaultWalletImpl is the default implementation of our normal, btcwallet

rpcserver.go

@@ -46,6 +46,7 @@ import (
  "github.com/lightningnetwork/lnd/contractcourt"
  "github.com/lightningnetwork/lnd/discovery"
  "github.com/lightningnetwork/lnd/feature"
+ "github.com/lightningnetwork/lnd/fn"
  "github.com/lightningnetwork/lnd/funding"
  "github.com/lightningnetwork/lnd/htlcswitch"
  "github.com/lightningnetwork/lnd/htlcswitch/hop"
@@ -82,6 +83,7 @@ import (
  "google.golang.org/grpc"
  "google.golang.org/grpc/codes"
  "google.golang.org/grpc/status"
+ "google.golang.org/protobuf/proto"
  "gopkg.in/macaroon-bakery.v2/bakery"
 )
 
@@ -567,6 +569,17 @@ func MainRPCServerPermissions() map[string][]bakery.Op {
  }
 }
 
+// AuxDataParser is an interface that is used to parse auxiliary custom data
+// within RPC messages. This is used to transform binary blobs to human-readable
+// JSON representations.
+type AuxDataParser interface {
+ // InlineParseCustomData replaces any custom data binary blob in the
+ // given RPC message with its corresponding JSON formatted data. This
+ // transforms the binary (likely TLV encoded) data to a human-readable
+ // JSON representation (still as byte slice).
+ InlineParseCustomData(msg proto.Message) error
+}
+
 // rpcServer is a gRPC, RPC front end to the lnd daemon.
 // TODO(roasbeef): pagination support for the list-style calls
 type rpcServer struct {
@@ -3544,7 +3557,7 @@ func (r *rpcServer) ChannelBalance(ctx context.Context,
  unsettledRemoteBalance, pendingOpenLocalBalance,
  pendingOpenRemoteBalance)
 
- return &lnrpc.ChannelBalanceResponse{
+ resp := &lnrpc.ChannelBalanceResponse{
  LocalBalance: &lnrpc.Amount{
  Sat: uint64(localBalance.ToSatoshis()),
  Msat: uint64(localBalance),
@@ -3574,7 +3587,19 @@ func (r *rpcServer) ChannelBalance(ctx context.Context,
  // Deprecated fields.
  Balance: int64(localBalance.ToSatoshis()),
  PendingOpenBalance: int64(pendingOpenLocalBalance.ToSatoshis()),
- }, nil
+ }
+
+ err = fn.MapOptionZ(
+ r.server.implCfg.AuxDataParser,
+ func(parser AuxDataParser) error {
+ return parser.InlineParseCustomData(resp)
+ },
+ )
+ if err != nil {
+ return nil, fmt.Errorf("error parsing custom data: %w", err)
+ }
+
+ return resp, nil
 }
 
 type (
@@ -4330,6 +4355,16 @@ func (r *rpcServer) ListChannels(ctx context.Context,
  resp.Channels = append(resp.Channels, channel)
  }
 
+ err = fn.MapOptionZ(
+ r.server.implCfg.AuxDataParser,
+ func(parser AuxDataParser) error {
+ return parser.InlineParseCustomData(resp)
+ },
+ )
+ if err != nil {
+ return nil, fmt.Errorf("error parsing custom data: %w", err)
+ }
+
  return resp, nil
 }