minor improvement

share/shwap/p2p/bitswap/block_registry.go

@@ -10,9 +10,9 @@ import (
 
 // EmptyBlock constructs an empty Block with type in the given CID.
 func EmptyBlock(cid cid.Cid) (Block, error) {
-	spec, ok := specRegistry[cid.Prefix().MhType]
-	if !ok {
-		return nil, fmt.Errorf("unsupported Block type: %v", cid.Prefix().MhType)
+	spec, err := getSpec(cid)
+	if err != nil {
+		return nil, err
 	}
 
 	blk, err := spec.builder(cid)
@@ -25,9 +25,9 @@ func EmptyBlock(cid cid.Cid) (Block, error) {
 
 // maxBlockSize returns the maximum size of the Block type in the given CID.
 func maxBlockSize(cid cid.Cid) (int, error) {
-	spec, ok := specRegistry[cid.Prefix().MhType]
-	if !ok {
-		return -1, fmt.Errorf("unsupported Block type: %v", cid.Prefix().MhType)
+	spec, err := getSpec(cid)
+	if err != nil {
+		return 0, err
 	}
 
 	return spec.maxSize, nil
@@ -38,24 +38,34 @@ func registerBlock(mhcode, codec uint64, maxSize, idSize int, bldrFn func(cid.Ci
 	mh.Register(mhcode, func() hash.Hash {
 		return &hasher{IDSize: idSize}
 	})
-	specRegistry[mhcode] = blockSpec{
+	specRegistry[codec] = blockSpec{
 		idSize:  idSize,
 		maxSize: maxSize,
-		codec:   codec,
+		mhCode:  mhcode,
 		builder: bldrFn,
 	}
 }
 
+// getSpec returns the blockSpec for the given CID.
+func getSpec(cid cid.Cid) (blockSpec, error) {
+	spec, ok := specRegistry[cid.Type()]
+	if !ok {
+		return blockSpec{}, fmt.Errorf("unsupported codec %d", cid.Type())
+	}
+
+	return spec, nil
+}
+
 // blockSpec holds constant metadata about particular Block types.
 type blockSpec struct {
 	idSize  int
 	maxSize int
-	codec   uint64
+	mhCode  uint64
 	builder func(cid.Cid) (Block, error)
 }
 
 func (spec *blockSpec) String() string {
-	return fmt.Sprintf("BlockSpec{IDSize: %d, Codec: %d}", spec.idSize, spec.codec)
+	return fmt.Sprintf("BlockSpec{IDSize: %d, MHCode: %d}", spec.idSize, spec.mhCode)
 }
 
 var specRegistry = make(map[uint64]blockSpec)

share/shwap/p2p/bitswap/cid.go

@@ -35,16 +35,18 @@ func encodeToCID(bm encoding.BinaryMarshaler, mhcode, codec uint64) cid.Cid {
 
 // validateCID checks correctness of the CID.
 func validateCID(cid cid.Cid) error {
-	prefix := cid.Prefix()
-	spec, ok := specRegistry[prefix.MhType]
-	if !ok {
-		return fmt.Errorf("unsupported multihash type %d", prefix.MhType)
+	spec, err := getSpec(cid)
+	if err != nil {
+		return err
 	}
 
-	if prefix.Codec != spec.codec {
-		return fmt.Errorf("invalid CID codec %d", prefix.Codec)
+	prefix := cid.Prefix()
+	if prefix.Version != 1 {
+		return fmt.Errorf("invalid cid version %d", prefix.Version)
+	}
+	if prefix.MhType != spec.mhCode {
+		return fmt.Errorf("invalid multihash type %d", prefix.MhType)
 	}
-
 	if prefix.MhLength != spec.idSize {
 		return fmt.Errorf("invalid multihash length %d", prefix.MhLength)
 	}