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getter.go
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getter.go
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package share
import (
"context"
"crypto/sha256"
"errors"
"fmt"
"github.com/celestiaorg/nmt"
"github.com/celestiaorg/rsmt2d"
"github.com/celestiaorg/celestia-node/header"
)
var (
// ErrNotFound is used to indicate that requested data could not be found.
ErrNotFound = errors.New("share: data not found")
// ErrOutOfBounds is used to indicate that a passed row or column index is out of bounds of the
// square size.
ErrOutOfBounds = errors.New("share: row or column index is larger than square size")
)
// Getter interface provides a set of accessors for shares by the Root.
// Automatically verifies integrity of shares(exceptions possible depending on the implementation).
//
//go:generate mockgen -destination=mocks/getter.go -package=mocks . Getter
type Getter interface {
// GetShare gets a Share by coordinates in EDS.
GetShare(ctx context.Context, header *header.ExtendedHeader, row, col int) (Share, error)
// GetEDS gets the full EDS identified by the given extended header.
GetEDS(context.Context, *header.ExtendedHeader) (*rsmt2d.ExtendedDataSquare, error)
// GetSharesByNamespace gets all shares from an EDS within the given namespace.
// Shares are returned in a row-by-row order if the namespace spans multiple rows.
// Inclusion of returned data could be verified using Verify method on NamespacedShares.
// If no shares are found for target namespace non-inclusion could be also verified by calling
// Verify method.
GetSharesByNamespace(context.Context, *header.ExtendedHeader, Namespace) (NamespacedShares, error)
}
// NamespacedShares represents all shares with proofs within a specific namespace of an EDS.
type NamespacedShares []NamespacedRow
// Flatten returns the concatenated slice of all NamespacedRow shares.
func (ns NamespacedShares) Flatten() []Share {
shares := make([]Share, 0)
for _, row := range ns {
shares = append(shares, row.Shares...)
}
return shares
}
// NamespacedRow represents all shares with proofs within a specific namespace of a single EDS row.
type NamespacedRow struct {
Shares []Share `json:"shares"`
Proof *nmt.Proof `json:"proof"`
}
// Verify validates NamespacedShares by checking every row with nmt inclusion proof.
func (ns NamespacedShares) Verify(root *Root, namespace Namespace) error {
var originalRoots [][]byte
for _, row := range root.RowRoots {
if !namespace.IsOutsideRange(row, row) {
originalRoots = append(originalRoots, row)
}
}
if len(originalRoots) != len(ns) {
return fmt.Errorf("amount of rows differs between root and namespace shares: expected %d, got %d",
len(originalRoots), len(ns))
}
for i, row := range ns {
// verify row data against row hash from original root
if !row.verify(originalRoots[i], namespace) {
return fmt.Errorf("row verification failed: row %d doesn't match original root: %s", i, root.String())
}
}
return nil
}
// verify validates the row using nmt inclusion proof.
func (row *NamespacedRow) verify(rowRoot []byte, namespace Namespace) bool {
// construct nmt leaves from shares by prepending namespace
leaves := make([][]byte, 0, len(row.Shares))
for _, shr := range row.Shares {
leaves = append(leaves, append(GetNamespace(shr), shr...))
}
// verify namespace
return row.Proof.VerifyNamespace(
sha256.New(),
namespace.ToNMT(),
leaves,
rowRoot,
)
}