chore!: consistent share prefix for tail padding (#1353)

pkg/appconsts/appconsts.go

@@ -97,10 +97,10 @@ var (
 	// PayForBlobNamespaceID is the namespace reserved for PayForBlobs transactions.
 	PayForBlobNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 4}
 
-	// ReservedNamespacePadding is the namespace used for padding after all
+	// ReservedPaddingNamespaceID is the namespace used for padding after all
 	// reserved namespaces. In practice this padding is after transactions
 	// (ordinary and PFBs) but before blobs.
-	ReservedNamespacePadding = namespace.ID{0, 0, 0, 0, 0, 0, 0, 255}
+	ReservedPaddingNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 255}
 
 	// MaxReservedNamespace is the lexicographically largest namespace that is
 	// reserved for protocol use.

pkg/da/data_availability_header.go

@@ -168,22 +168,14 @@ func (dah *DataAvailabilityHeader) IsZero() bool {
 }
 
 // MinDataAvailabilityHeader returns the minimum valid data availability header.
-// It is equal to the data availability header for an empty block
+// It is equal to the data availability header for a block with one tail padding
+// share.
 func MinDataAvailabilityHeader() DataAvailabilityHeader {
-	shares := GenerateEmptyShares(appconsts.MinShareCount)
-	eds, err := ExtendShares(appconsts.DefaultMinSquareSize, shares)
+	s := shares.ToBytes(shares.TailPaddingShares(appconsts.MinShareCount))
+	eds, err := ExtendShares(appconsts.DefaultMinSquareSize, s)
 	if err != nil {
 		panic(err)
 	}
 	dah := NewDataAvailabilityHeader(eds)
 	return dah
 }
-
-// GenerateEmptyShares generate an array of empty shares
-func GenerateEmptyShares(size int) [][]byte {
-	result := make([][]byte, size)
-	for i := 0; i < size; i++ {
-		result[i] = shares.TailPaddingShare()
-	}
-	return result
-}

pkg/da/data_availability_header_test.go

@@ -25,14 +25,11 @@ func TestNilDataAvailabilityHeaderHashDoesntCrash(t *testing.T) {
 func TestMinDataAvailabilityHeader(t *testing.T) {
 	dah := MinDataAvailabilityHeader()
 	expectedHash := []byte{
-		0x6f, 0x52, 0xda, 0xc1, 0x65, 0x45, 0xe4, 0x57, 0x25, 0xbe, 0x6e, 0xa3, 0x2a, 0xed, 0x55, 0x26,
-		0x6e, 0x45, 0x3, 0x48, 0x0, 0xee, 0xe1, 0xd8, 0x7c, 0x94, 0x28, 0xf4, 0x84, 0x4e, 0xa4, 0x7a,
+		0x25, 0x77, 0x60, 0x46, 0x19, 0x93, 0xf8, 0xf1, 0x97, 0xb4, 0x21, 0xec, 0x74, 0x35, 0xf3, 0xc3,
+		0x6c, 0x37, 0x34, 0x92, 0x3e, 0x3d, 0xa9, 0xa4, 0x2d, 0xc7, 0x3b, 0x5, 0xf0, 0x7b, 0x3d, 0x8,
 	}
 	require.Equal(t, expectedHash, dah.hash)
 	require.NoError(t, dah.ValidateBasic())
-	// important note: also see the types.TestEmptyBlockDataAvailabilityHeader test
-	// which ensures that empty block data results in the minimum data availability
-	// header
 }
 
 func TestNewDataAvailabilityHeader(t *testing.T) {

pkg/shares/padding.go

@@ -0,0 +1,66 @@
+package shares
+
+import (
+	"bytes"
+	"encoding/binary"
+
+	"github.com/celestiaorg/celestia-app/pkg/appconsts"
+	"github.com/celestiaorg/nmt/namespace"
+)
+
+// NamespacePaddingShare returns a share that acts as padding. Namespace padding
+// shares follow a blob so that the next blob may start at an index that
+// conforms to non-interactive default rules. The ns parameter provided should
+// be the namespace of the blob that precedes this padding in the data square.
+func NamespacePaddingShare(ns namespace.ID) Share {
+	infoByte, err := NewInfoByte(appconsts.ShareVersionZero, true)
+	if err != nil {
+		panic(err)
+	}
+
+	sequenceLen := make([]byte, appconsts.SequenceLenBytes)
+	binary.BigEndian.PutUint32(sequenceLen, uint32(0))
+
+	padding := bytes.Repeat([]byte{0}, appconsts.FirstSparseShareContentSize)
+
+	share := make([]byte, 0, appconsts.ShareSize)
+	share = append(share, ns...)
+	share = append(share, byte(infoByte))
+	share = append(share, sequenceLen...)
+	share = append(share, padding...)
+	return share
+}
+
+// NamespacePaddingShares returns n namespace padding shares.
+func NamespacePaddingShares(ns namespace.ID, n int) []Share {
+	shares := make([]Share, n)
+	for i := 0; i < n; i++ {
+		shares[i] = NamespacePaddingShare(ns)
+	}
+	return shares
+}
+
+// ReservedPaddingShare returns a share that acts as padding. Reserved padding
+// shares follow all significant shares in the reserved namespace so that the
+// first blob can start at an index that conforms to non-interactive default
+// rules.
+func ReservedPaddingShare() Share {
+	return NamespacePaddingShare(appconsts.ReservedPaddingNamespaceID)
+}
+
+// ReservedPaddingShare returns n reserved padding shares.
+func ReservedPaddingShares(n int) []Share {
+	return NamespacePaddingShares(appconsts.ReservedPaddingNamespaceID, n)
+}
+
+// TailPaddingShare is a share that is used to pad a data square to the desired
+// square size. Tail padding shares follow the last blob share in the data
+// square.
+func TailPaddingShare() Share {
+	return NamespacePaddingShare(appconsts.TailPaddingNamespaceID)
+}
+
+// TailPaddingShares returns n tail padding shares.
+func TailPaddingShares(n int) []Share {
+	return NamespacePaddingShares(appconsts.TailPaddingNamespaceID, n)
+}

pkg/shares/padding_test.go

@@ -0,0 +1,65 @@
+package shares
+
+import (
+	"testing"
+
+	"github.com/celestiaorg/celestia-app/pkg/appconsts"
+	"github.com/celestiaorg/nmt/namespace"
+	"github.com/stretchr/testify/assert"
+)
+
+var nsOne = namespace.ID{1, 1, 1, 1, 1, 1, 1, 1}
+
+var nsOnePadding, _ = zeroPadIfNecessary([]byte{
+	1, 1, 1, 1, 1, 1, 1, 1, // namespace ID
+	1,          // info byte
+	0, 0, 0, 0, // sequence len
+}, appconsts.ShareSize)
+
+var reservedPadding, _ = zeroPadIfNecessary([]byte{
+	0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, // namespace ID
+	1,          // info byte
+	0, 0, 0, 0, // sequence len
+}, appconsts.ShareSize)
+
+var tailPadding, _ = zeroPadIfNecessary([]byte{
+	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, // namespace ID
+	1,          // info byte
+	0, 0, 0, 0, // sequence len
+}, appconsts.ShareSize)
+
+func TestNamespacePaddingShare(t *testing.T) {
+	got := NamespacePaddingShare(nsOne).ToBytes()
+	assert.Equal(t, nsOnePadding, got)
+}
+
+func TestNamespacePaddingShares(t *testing.T) {
+	shares := NamespacePaddingShares(nsOne, 2)
+	for _, share := range shares {
+		assert.Equal(t, nsOnePadding, share.ToBytes())
+	}
+}
+
+func TestReservedPaddingShare(t *testing.T) {
+	got := ReservedPaddingShare().ToBytes()
+	assert.Equal(t, reservedPadding, got)
+}
+
+func TestReservedPaddingShares(t *testing.T) {
+	shares := ReservedPaddingShares(2)
+	for _, share := range shares {
+		assert.Equal(t, reservedPadding, share.ToBytes())
+	}
+}
+
+func TestTailPaddingShare(t *testing.T) {
+	got := TailPaddingShare().ToBytes()
+	assert.Equal(t, tailPadding, got)
+}
+
+func TestTailPaddingShares(t *testing.T) {
+	shares := TailPaddingShares(2)
+	for _, share := range shares {
+		assert.Equal(t, tailPadding, share.ToBytes())
+	}
+}

pkg/shares/parse_sparse_shares.go

@@ -31,11 +31,11 @@ func parseSparseShares(rawShares [][]byte, supportedShareVersions []uint8) (blob
 			return nil, fmt.Errorf("unsupported share version %v is not present in supported share versions %v", version, supportedShareVersions)
 		}
 
-		isNamespacedPadded, err := IsNamespacedPadded(share)
+		isPadding, err := share.IsPadding()
 		if err != nil {
 			return nil, err
 		}
-		if isNamespacedPadded {
+		if isPadding {
 			continue
 		}
 

pkg/shares/share_splitting.go

@@ -49,7 +49,7 @@ func Split(data coretypes.Data, useShareIndexes bool) ([]Share, error) {
 			blobShareStart = int(blobIndexes[0])
 		}
 
-		padding = NamespacedPaddedShares(appconsts.ReservedNamespacePadding, blobShareStart-currentShareCount)
+		padding = NamespacePaddingShares(appconsts.ReservedPaddingNamespaceID, blobShareStart-currentShareCount)
 	}
 	currentShareCount += len(padding)