go/consensus: Also try to answer light block requests from store

go/consensus/api/light.go

@@ -22,6 +22,10 @@ type LightService interface {
 
 // LightClient is a consensus light client interface.
 type LightClient interface {
+	// GetStoredLightBlock retrieves a light block from the local light block store without doing
+	// any remote queries.
+	GetStoredLightBlock(height int64) (*LightBlock, error)
+
 	// GetLightBlock queries peers for a specific light block.
 	GetLightBlock(ctx context.Context, height int64) (*LightBlock, rpc.PeerFeedback, error)
 

go/consensus/cometbft/cometbft.go

@@ -33,6 +33,12 @@ func New(
 }
 
 // NewLightClient creates a new CometBFT light client service.
-func NewLightClient(ctx context.Context, dataDir string, genesis *genesisAPI.Document, consensus consensusAPI.Backend, p2p rpc.P2P) (lightAPI.ClientService, error) {
+func NewLightClient(
+	ctx context.Context,
+	dataDir string,
+	genesis *genesisAPI.Document,
+	consensus consensusAPI.Backend,
+	p2p rpc.P2P,
+) (lightAPI.ClientService, error) {
 	return light.New(ctx, dataDir, genesis, consensus, p2p)
 }

go/consensus/cometbft/full/full.go

@@ -47,7 +47,6 @@ import (
 	"github.com/oasisprotocol/oasis-core/go/consensus/cometbft/db"
 	lightAPI "github.com/oasisprotocol/oasis-core/go/consensus/cometbft/light/api"
 	"github.com/oasisprotocol/oasis-core/go/consensus/metrics"
-	lightP2P "github.com/oasisprotocol/oasis-core/go/consensus/p2p/light"
 	genesisAPI "github.com/oasisprotocol/oasis-core/go/genesis/api"
 	cmflags "github.com/oasisprotocol/oasis-core/go/oasis-node/cmd/common/flags"
 	cmmetrics "github.com/oasisprotocol/oasis-core/go/oasis-node/cmd/common/metrics"
@@ -473,9 +472,6 @@ func (t *fullService) RegisterP2PService(p2p p2pAPI.Service) error {
 	}
 	t.p2p = p2p
 
-	// Register consensus protocol server.
-	t.p2p.RegisterProtocolServer(lightP2P.NewServer(t.p2p, t.genesis.ChainContext(), t))
-
 	return nil
 }
 

go/consensus/cometbft/light/api/light.go

@@ -3,6 +3,7 @@ package api
 
 import (
 	"context"
+	"fmt"
 
 	cmtlight "github.com/cometbft/cometbft/light"
 	cmtlightprovider "github.com/cometbft/cometbft/light/provider"
@@ -54,3 +55,20 @@ type ClientConfig struct {
 	// TrustOptions are CometBFT light client trust options.
 	TrustOptions cmtlight.TrustOptions
 }
+
+// NewLightBlock creates a new consensus.LightBlock from a CometBFT light block.
+func NewLightBlock(clb *cmttypes.LightBlock) (*consensus.LightBlock, error) {
+	plb, err := clb.ToProto()
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal light block: %w", err)
+	}
+	meta, err := plb.Marshal()
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal light block: %w", err)
+	}
+
+	return &consensus.LightBlock{
+		Height: clb.Height,
+		Meta:   meta,
+	}, nil
+}

go/consensus/cometbft/light/internal.go

@@ -61,6 +61,15 @@ func tryProviders[R any](
 	return result, nil, err
 }
 
+// GetStoredBlock implements api.Client.
+func (lc *lightClient) GetStoredLightBlock(height int64) (*consensus.LightBlock, error) {
+	clb, err := lc.tmc.TrustedLightBlock(height)
+	if err != nil {
+		return nil, err
+	}
+	return api.NewLightBlock(clb)
+}
+
 // GetLightBlock implements api.Client.
 func (lc *lightClient) GetLightBlock(ctx context.Context, height int64) (*consensus.LightBlock, rpc.PeerFeedback, error) {
 	return tryProviders(ctx, lc, func(p api.Provider) (*consensus.LightBlock, rpc.PeerFeedback, error) {

go/consensus/cometbft/light/p2p/p2p.go

@@ -245,6 +245,12 @@ func (lp *lightClientProvider) SubmitEvidence(ctx context.Context, evidence *con
 	return pf, nil
 }
 
+// GetStoredLightBlock implements api.Provider.
+func (lp *lightClientProvider) GetStoredLightBlock(_ int64) (*consensus.LightBlock, error) {
+	// The remote client provider stores no blocks locally.
+	return nil, consensus.ErrVersionNotFound
+}
+
 // GetLightBlock implements api.Provider.
 func (lp *lightClientProvider) GetLightBlock(ctx context.Context, height int64) (*consensus.LightBlock, rpc.PeerFeedback, error) {
 	peerID := lp.getPeer()

go/consensus/cometbft/light/service.go

@@ -258,6 +258,15 @@ func (c *client) worker() {
 	}
 }
 
+// GetStoredBlock implements api.Client.
+func (c *client) GetStoredLightBlock(height int64) (*consensus.LightBlock, error) {
+	clb, err := c.store.LightBlock(height)
+	if err != nil {
+		return nil, err
+	}
+	return api.NewLightBlock(clb)
+}
+
 // GetLightBlock implements api.Client.
 func (c *client) GetLightBlock(ctx context.Context, height int64) (*consensus.LightBlock, rpc.PeerFeedback, error) {
 	select {
@@ -291,19 +300,11 @@ func (c *client) GetLightBlock(ctx context.Context, height int64) (*consensus.Li
 			return nil, nil, err
 		}
 
-		plb, err := clb.ToProto()
+		lb, err := api.NewLightBlock(clb)
 		if err != nil {
-			return nil, nil, fmt.Errorf("failed to marshal light block: %w", err)
-		}
-		meta, err := plb.Marshal()
-		if err != nil {
-			return nil, nil, fmt.Errorf("failed to marshal light block: %w", err)
+			return nil, nil, err
 		}
-
-		return &consensus.LightBlock{
-			Height: clb.Height,
-			Meta:   meta,
-		}, rpc.NewNopPeerFeedback(), nil
+		return lb, rpc.NewNopPeerFeedback(), nil
 	}
 
 	// Direct peer query.

go/consensus/p2p/light/server.go

@@ -20,7 +20,9 @@ const (
 
 type service struct {
 	consensus consensus.Backend
-	logger    *logging.Logger
+	lc        consensus.LightClient
+
+	logger *logging.Logger
 }
 
 func (s *service) HandleRequest(ctx context.Context, method string, body cbor.RawMessage) (interface{}, error) {
@@ -30,12 +32,7 @@ func (s *service) HandleRequest(ctx context.Context, method string, body cbor.Ra
 		if err := cbor.Unmarshal(body, &rq); err != nil {
 			return nil, rpc.ErrBadRequest
 		}
-
-		lb, err := s.consensus.GetLightBlock(ctx, rq)
-		if err != nil {
-			return nil, err
-		}
-		return lb, nil
+		return s.handleGetLightBlock(ctx, rq)
 	case MethodGetParameters:
 		var rq int64
 		if err := cbor.Unmarshal(body, &rq); err != nil {
@@ -59,11 +56,32 @@ func (s *service) HandleRequest(ctx context.Context, method string, body cbor.Ra
 	}
 }
 
+func (s *service) handleGetLightBlock(ctx context.Context, height int64) (*consensus.LightBlock, error) {
+	lb, err := s.consensus.GetLightBlock(ctx, height)
+	if err != nil {
+		// Also try the local light store.
+		if lb, err = s.lc.GetStoredLightBlock(height); err != nil {
+			return nil, err
+		}
+	}
+	return lb, nil
+}
+
 // NewServer creates a new light block sync protocol server.
-func NewServer(p2p rpc.P2P, chainContext string, consensus consensus.Backend) rpc.Server {
+func NewServer(
+	p2p rpc.P2P,
+	chainContext string,
+	consensus consensus.Backend,
+	lightClient consensus.LightClient,
+) rpc.Server {
 	p2p.RegisterProtocol(ProtocolID(chainContext), minProtocolPeers, totalProtocolPeers)
+
 	return rpc.NewServer(
 		ProtocolID(chainContext),
-		&service{consensus, logging.GetLogger("consensus/p22/light/server")},
+		&service{
+			consensus: consensus,
+			lc:        lightClient,
+			logger:    logging.GetLogger("consensus/p2p/light/server"),
+		},
 	)
 }

go/oasis-node/cmd/node/node.go

@@ -18,6 +18,7 @@ import (
 	"github.com/oasisprotocol/oasis-core/go/config"
 	consensusAPI "github.com/oasisprotocol/oasis-core/go/consensus/api"
 	"github.com/oasisprotocol/oasis-core/go/consensus/cometbft"
+	consensusLightP2P "github.com/oasisprotocol/oasis-core/go/consensus/p2p/light"
 	controlAPI "github.com/oasisprotocol/oasis-core/go/control/api"
 	genesisAPI "github.com/oasisprotocol/oasis-core/go/genesis/api"
 	governanceAPI "github.com/oasisprotocol/oasis-core/go/governance/api"
@@ -581,6 +582,9 @@ func NewNode() (node *Node, err error) { // nolint: gocyclo
 	}
 	node.svcMgr.Register(node.LightClient)
 
+	// Register consensus light client P2P protocol server.
+	node.P2P.RegisterProtocolServer(consensusLightP2P.NewServer(node.P2P, node.chainContext, node.Consensus, node.LightClient))
+
 	// If the consensus backend supports communicating with consensus services, we can also start
 	// all services required for runtime operation.
 	if node.Consensus.SupportedFeatures().Has(consensusAPI.FeatureServices) {