feat(header)!: introduce header.Header interface (#1304)

Most important changes in this PR:
* `tmbytes.HexBytes` replaced by `header.Hash`
* `header.Header` used in interfaces in `header` package
* `IsBefore` inlined, so we don't need to include this method in interface (it's a oneliner used once)
* `VerifyNonAdjacent` added to `Header` interface (at least for now)
* Generics introduced to avoid casting

Resolves evstack/ev-node#575.

Author: tzdybal

header/core/exchange.go

@@ -8,10 +8,9 @@ import (
 	"github.com/ipfs/go-blockservice"
 	logging "github.com/ipfs/go-log/v2"
 
-	tmbytes "github.com/tendermint/tendermint/libs/bytes"
-
 	"github.com/celestiaorg/celestia-node/core"
 	"github.com/celestiaorg/celestia-node/header"
+	libhead "github.com/celestiaorg/celestia-node/libs/header"
 )
 
 var log = logging.Logger("header/core")
@@ -57,7 +56,7 @@ func (ce *Exchange) GetRangeByHeight(ctx context.Context, from, amount uint64) (
 
 func (ce *Exchange) GetVerifiedRange(ctx context.Context, from *header.ExtendedHeader, amount uint64,
 ) ([]*header.ExtendedHeader, error) {
-	headers, err := ce.GetRangeByHeight(ctx, uint64(from.Height)+1, amount)
+	headers, err := ce.GetRangeByHeight(ctx, uint64(from.Height())+1, amount)
 	if err != nil {
 		return nil, err
 	}
@@ -72,7 +71,7 @@ func (ce *Exchange) GetVerifiedRange(ctx context.Context, from *header.ExtendedH
 	return headers, nil
 }
 
-func (ce *Exchange) Get(ctx context.Context, hash tmbytes.HexBytes) (*header.ExtendedHeader, error) {
+func (ce *Exchange) Get(ctx context.Context, hash libhead.Hash) (*header.ExtendedHeader, error) {
 	log.Debugw("requesting header", "hash", hash.String())
 	block, err := ce.fetcher.GetBlockByHash(ctx, hash)
 	if err != nil {

header/core/listener.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/celestiaorg/celestia-node/core"
 	"github.com/celestiaorg/celestia-node/header"
+	libhead "github.com/celestiaorg/celestia-node/libs/header"
 )
 
 // Listener is responsible for listening to Core for
@@ -20,15 +21,15 @@ import (
 // broadcasts the new `ExtendedHeader` to the header-sub gossipsub
 // network.
 type Listener struct {
-	bcast     header.Broadcaster
+	bcast     libhead.Broadcaster[*header.ExtendedHeader]
 	fetcher   *core.BlockFetcher
 	bServ     blockservice.BlockService
 	construct header.ConstructFn
 	cancel    context.CancelFunc
 }
 
 func NewListener(
-	bcast header.Broadcaster,
+	bcast libhead.Broadcaster[*header.ExtendedHeader],
 	fetcher *core.BlockFetcher,
 	bServ blockservice.BlockService,
 	construct header.ConstructFn,
@@ -98,7 +99,7 @@ func (cl *Listener) listen(ctx context.Context, sub <-chan *types.Block) {
 			// broadcast new ExtendedHeader, but if core is still syncing, notify only local subscribers
 			err = cl.bcast.Broadcast(ctx, eh, pubsub.WithLocalPublication(syncing))
 			if err != nil {
-				log.Errorw("listener: broadcasting next header", "height", eh.Height,
+				log.Errorw("listener: broadcasting next header", "height", eh.Height(),
 					"err", err)
 			}
 		case <-ctx.Done():

header/core/listener_test.go

@@ -14,7 +14,7 @@ import (
 
 	"github.com/celestiaorg/celestia-node/core"
 	"github.com/celestiaorg/celestia-node/header"
-	"github.com/celestiaorg/celestia-node/header/p2p"
+	"github.com/celestiaorg/celestia-node/libs/header/p2p"
 )
 
 // TestListener tests the lifecycle of the core listener.
@@ -94,7 +94,7 @@ func createListener(
 	fetcher *core.BlockFetcher,
 	ps *pubsub.PubSub,
 ) *Listener {
-	p2pSub := p2p.NewSubscriber(ps)
+	p2pSub := p2p.NewSubscriber[*header.ExtendedHeader](ps, header.MsgID)
 	err := p2pSub.Start(ctx)
 	require.NoError(t, err)
 	t.Cleanup(func() {

header/header.go

@@ -5,23 +5,33 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"time"
 
 	"github.com/ipfs/go-blockservice"
 	logging "github.com/ipfs/go-log/v2"
 
-	bts "github.com/tendermint/tendermint/libs/bytes"
 	amino "github.com/tendermint/tendermint/libs/json"
 	core "github.com/tendermint/tendermint/types"
 
 	appshares "github.com/celestiaorg/celestia-app/pkg/shares"
 
 	"github.com/celestiaorg/celestia-app/pkg/da"
 
+	libhead "github.com/celestiaorg/celestia-node/libs/header"
 	"github.com/celestiaorg/celestia-node/share"
 )
 
 var log = logging.Logger("header")
 
+// ConstructFn aliases a function that creates an ExtendedHeader.
+type ConstructFn = func(
+	context.Context,
+	*core.Block,
+	*core.Commit,
+	*core.ValidatorSet,
+	blockservice.BlockService,
+) (*ExtendedHeader, error)
+
 type DataAvailabilityHeader = da.DataAvailabilityHeader
 
 // EmptyDAH provides DAH of the empty block.
@@ -42,6 +52,28 @@ type ExtendedHeader struct {
 	DAH          *DataAvailabilityHeader `json:"dah"`
 }
 
+func (eh *ExtendedHeader) New() libhead.Header {
+	return new(ExtendedHeader)
+}
+
+func (eh *ExtendedHeader) IsZero() bool {
+	return eh == nil
+}
+
+func (eh *ExtendedHeader) ChainID() string {
+	return eh.RawHeader.ChainID
+}
+
+func (eh *ExtendedHeader) Height() int64 {
+	return eh.RawHeader.Height
+}
+
+func (eh *ExtendedHeader) Time() time.Time {
+	return eh.RawHeader.Time
+}
+
+var _ libhead.Header = &ExtendedHeader{}
+
 // MakeExtendedHeader assembles new ExtendedHeader.
 func MakeExtendedHeader(
 	ctx context.Context,
@@ -73,33 +105,30 @@ func MakeExtendedHeader(
 		Commit:       comm,
 		ValidatorSet: vals,
 	}
-	return eh, eh.ValidateBasic()
+	return eh, eh.Validate()
 }
 
 // Hash returns Hash of the wrapped RawHeader.
 // NOTE: It purposely overrides Hash method of RawHeader to get it directly from Commit without
 // recomputing.
-func (eh *ExtendedHeader) Hash() bts.HexBytes {
-	return eh.Commit.BlockID.Hash
+func (eh *ExtendedHeader) Hash() libhead.Hash {
+	return libhead.Hash(eh.Commit.BlockID.Hash)
 }
 
 // LastHeader returns the Hash of the last wrapped RawHeader.
-func (eh *ExtendedHeader) LastHeader() bts.HexBytes {
-	return eh.RawHeader.LastBlockID.Hash
+func (eh *ExtendedHeader) LastHeader() libhead.Hash {
+	return libhead.Hash(eh.RawHeader.LastBlockID.Hash)
 }
 
 // IsBefore returns whether the given header is of a higher height.
-func (eh *ExtendedHeader) IsBefore(h *ExtendedHeader) bool {
-	return eh.Height < h.Height
-}
 
 // Equals returns whether the hash and height of the given header match.
 func (eh *ExtendedHeader) Equals(header *ExtendedHeader) bool {
-	return eh.Height == header.Height && bytes.Equal(eh.Hash(), header.Hash())
+	return eh.Height() == header.Height() && bytes.Equal(eh.Hash(), header.Hash())
 }
 
-// ValidateBasic performs *basic* validation to check for missed/incorrect fields.
-func (eh *ExtendedHeader) ValidateBasic() error {
+// Validate performs *basic* validation to check for missed/incorrect fields.
+func (eh *ExtendedHeader) Validate() error {
 	err := eh.RawHeader.ValidateBasic()
 	if err != nil {
 		return err
@@ -122,7 +151,7 @@ func (eh *ExtendedHeader) ValidateBasic() error {
 		)
 	}
 
-	if err := eh.ValidatorSet.VerifyCommitLight(eh.ChainID, eh.Commit.BlockID, eh.Height, eh.Commit); err != nil {
+	if err := eh.ValidatorSet.VerifyCommitLight(eh.ChainID(), eh.Commit.BlockID, eh.Height(), eh.Commit); err != nil {
 		return err
 	}
 

header/header_test.go

@@ -43,6 +43,6 @@ func TestMismatchedDataHash_ComputedRoot(t *testing.T) {
 
 	header.DataHash = rand.Bytes(32)
 
-	err := header.ValidateBasic()
+	err := header.Validate()
 	assert.ErrorContains(t, err, "mismatch between data hash")
 }

header/local/exchange.go

@@ -7,12 +7,14 @@ import (
 	"go.opentelemetry.io/otel/metric/global"
 	"go.opentelemetry.io/otel/metric/instrument"
 	"go.opentelemetry.io/otel/metric/unit"
+
+	libhead "github.com/celestiaorg/celestia-node/libs/header"
 )
 
 var meter = global.MeterProvider().Meter("header")
 
 // WithMetrics enables Otel metrics to monitor head.
-func WithMetrics(store Store) {
+func WithMetrics(store libhead.Store[*ExtendedHeader]) {
 	headC, _ := meter.AsyncInt64().Counter(
 		"head",
 		instrument.WithUnit(unit.Dimensionless),
@@ -32,7 +34,7 @@ func WithMetrics(store Store) {
 
 			headC.Observe(
 				ctx,
-				head.Height,
+				head.Height(),
 				attribute.Int("square_size", len(head.DAH.RowsRoots)),
 			)
 		},