chore(ipld): extract byzantine error and constructor for it into a se…

…parate file

ipld/get.go

@@ -2,7 +2,6 @@ package ipld
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/ipfs/go-cid"
 	ipld "github.com/ipfs/go-ipld-format"
@@ -13,20 +12,6 @@ import (
 	"github.com/celestiaorg/nmt/namespace"
 )
 
-// ErrByzantine is an error converted from rsmt2d.ByzantineRow/Col +
-// Merkle Proof of each share.
-type ErrByzantine struct {
-	Index  uint8
-	Shares []*ShareWithProof
-	// TODO(@vgokivs): Change to enum type and rename to Axis after
-	// updating rsmt2d
-	IsRow bool
-}
-
-func (e *ErrByzantine) Error() string {
-	return fmt.Sprintf("byzantine error. isRow:%v, Index:%v", e.IsRow, e.Index)
-}
-
 // GetShare fetches and returns the data for leaf `leafIndex` of root `rootCid`.
 func GetShare(
 	ctx context.Context,

ipld/retriever.go

@@ -14,7 +14,6 @@ import (
 	"github.com/tendermint/tendermint/pkg/da"
 	"github.com/tendermint/tendermint/pkg/wrapper"
 
-	"github.com/celestiaorg/celestia-node/ipld/plugin"
 	"github.com/celestiaorg/nmt"
 	"github.com/celestiaorg/rsmt2d"
 )
@@ -58,8 +57,12 @@ func (r *Retriever) Retrieve(ctx context.Context, dah *da.DataAvailabilityHeader
 			if err == nil {
 				return eds, nil
 			}
-			if byzErr := r.checkForByzantineError(ctx, dah, err); byzErr != nil {
-				return nil, byzErr
+			var (
+				errRow *rsmt2d.ErrByzantineRow
+				errCol *rsmt2d.ErrByzantineCol
+			)
+			if errors.As(err, &errRow) || errors.As(err, &errCol) {
+				return nil, NewErrByzantine(ctx, r.dag, dah, errRow, errCol)
 			}
 			log.Warnw("not enough shares to reconstruct data square, requesting more...", "err", err)
 		}
@@ -69,50 +72,6 @@ func (r *Retriever) Retrieve(ctx context.Context, dah *da.DataAvailabilityHeader
 	return nil, format.ErrNotFound
 }
 
-// checkForByzantineError ensures that passed error is rsmt2d.ErrByzantineRow/Col,
-// fetches proof for every share from row or col and converts error to ErrByzantine
-func (r *Retriever) checkForByzantineError(
-	ctx context.Context,
-	dah *da.DataAvailabilityHeader,
-	byzErr error,
-) error {
-	var (
-		errRow *rsmt2d.ErrByzantineRow
-		errCol *rsmt2d.ErrByzantineCol
-	)
-	if !errors.As(byzErr, &errRow) && !errors.As(byzErr, &errCol) {
-		return nil
-	}
-	var (
-		errShares [][]byte
-		root      []byte
-		index     uint8
-	)
-	isRow := false
-	if errRow != nil {
-		errShares = errRow.Shares
-		root = dah.RowsRoots[errRow.RowNumber]
-		index = uint8(errRow.RowNumber)
-		isRow = true
-	} else {
-		errShares = errCol.Shares
-		root = dah.ColumnRoots[errCol.ColNumber]
-		index = uint8(errCol.ColNumber)
-	}
-
-	sharesWithProof, err := GetProofsForShares(
-		ctx,
-		r.dag,
-		plugin.MustCidFromNamespacedSha256(root),
-		errShares,
-	)
-	if err != nil {
-		return err
-	}
-
-	return &ErrByzantine{Index: index, Shares: sharesWithProof, IsRow: isRow}
-}
-
 type retrieverSession struct {
 	dag   format.NodeGetter
 	adder *NmtNodeAdder

ipld/retriever_byzantine.go

@@ -0,0 +1,73 @@
+package ipld
+
+import (
+	"context"
+	"fmt"
+
+	format "github.com/ipfs/go-ipld-format"
+	"github.com/tendermint/tendermint/pkg/da"
+
+	"github.com/celestiaorg/celestia-node/ipld/plugin"
+	"github.com/celestiaorg/rsmt2d"
+)
+
+// ErrByzantine is a thrown when recovered data square is not correct
+// (merkle proofs do not match parity erasure-coding data).
+//
+// It is converted from rsmt2d.ByzantineRow/Col +
+// Merkle Proof for each share.
+type ErrByzantine struct {
+	Index  uint8
+	Shares []*ShareWithProof
+	// TODO(@vgokivs): Change to enum type and rename to Axis after
+	// updating rsmt2d
+	IsRow bool
+}
+
+func (e *ErrByzantine) Error() string {
+	return fmt.Sprintf("byzantine error. isRow:%v, Index:%v", e.IsRow, e.Index)
+}
+
+// NewErrByzantine creates new ErrByzantine from rsmt2d error.
+// If error happens during proof collection, it terminates the process with os.Exit(1).
+// TODO(@Wondertan): Migrate to ErrByzantineData in the newest rsmt2d
+func NewErrByzantine(
+	ctx context.Context,
+	dag format.NodeGetter,
+	dah *da.DataAvailabilityHeader,
+	errRow *rsmt2d.ErrByzantineRow,
+	errCol *rsmt2d.ErrByzantineCol) *ErrByzantine {
+	var (
+		errShares [][]byte
+		root      []byte
+		index     uint8
+	)
+	isRow := false
+	if errRow != nil {
+		errShares = errRow.Shares
+		root = dah.RowsRoots[errRow.RowNumber]
+		index = uint8(errRow.RowNumber)
+		isRow = true
+	} else {
+		errShares = errCol.Shares
+		root = dah.ColumnRoots[errCol.ColNumber]
+		index = uint8(errCol.ColNumber)
+	}
+
+	sharesWithProof, err := GetProofsForShares(
+		ctx,
+		dag,
+		plugin.MustCidFromNamespacedSha256(root),
+		errShares,
+	)
+	if err != nil {
+		// Fatal as rsmt2d proved that error is byzantine,
+		// but we cannot properly collect the proof,
+		// so verification will fail and thus services won't be stopped
+		// while we still have to stop them.
+		// TODO(@Wondertan): Find a better way to handle
+		log.Fatalw("getting proof for ErrByzantine", "err", err)
+	}
+
+	return &ErrByzantine{Index: index, Shares: sharesWithProof, IsRow: isRow}
+}