From e23dbd291be024b369c43709357d85b51c14ddd4 Mon Sep 17 00:00:00 2001
From: Kevin Atkinson <k@kevina.org>
Date: Sat, 13 May 2017 00:35:22 -0400
Subject: [PATCH] Add support for using an alternative hash function with raw
 nodes.

License: MIT
Signed-off-by: Kevin Atkinson <k@kevina.org>
---
 importer/helpers/dagbuilder.go | 19 +++++++++++++++----
 merkledag/merkledag.go         |  2 +-
 merkledag/raw.go               | 20 ++++++++++++++++++++
 3 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/importer/helpers/dagbuilder.go b/importer/helpers/dagbuilder.go
index a06b38c59..de33563ef 100644
--- a/importer/helpers/dagbuilder.go
+++ b/importer/helpers/dagbuilder.go
@@ -165,10 +165,21 @@ func (db *DagBuilderHelper) GetNextDataNode() (*UnixfsNode, error) {
 	}
 
 	if db.rawLeaves {
-		return &UnixfsNode{
-			rawnode: dag.NewRawNode(data),
-			raw:     true,
-		}, nil
+		if db.prefix == nil {
+			return &UnixfsNode{
+				rawnode: dag.NewRawNode(data),
+				raw:     true,
+			}, nil
+		} else {
+			rawnode, err := dag.NewRawNodeWPrefix(data, *db.prefix)
+			if err != nil {
+				return nil, err
+			}
+			return &UnixfsNode{
+				rawnode: rawnode,
+				raw:     true,
+			}, nil
+		}
 	} else {
 		blk := db.NewUnixfsBlock()
 		blk.SetData(data)
diff --git a/merkledag/merkledag.go b/merkledag/merkledag.go
index e0dc5c74a..5509bcaeb 100644
--- a/merkledag/merkledag.go
+++ b/merkledag/merkledag.go
@@ -116,7 +116,7 @@ func decodeBlock(b blocks.Block) (node.Node, error) {
 		decnd.Prefix = b.Cid().Prefix()
 		return decnd, nil
 	case cid.Raw:
-		return NewRawNode(b.RawData()), nil
+		return NewRawNodeWPrefix(b.RawData(), b.Cid().Prefix())
 	case cid.DagCBOR:
 		return ipldcbor.Decode(b.RawData())
 	default:
diff --git a/merkledag/raw.go b/merkledag/raw.go
index 30fe639af..7c5ba56af 100644
--- a/merkledag/raw.go
+++ b/merkledag/raw.go
@@ -12,6 +12,8 @@ type RawNode struct {
 	blocks.Block
 }
 
+// NewRawNode creates a RawNode using the default sha2-256 hash
+// funcition.
 func NewRawNode(data []byte) *RawNode {
 	h := u.Hash(data)
 	c := cid.NewCidV1(cid.Raw, h)
@@ -20,6 +22,24 @@ func NewRawNode(data []byte) *RawNode {
 	return &RawNode{blk}
 }
 
+// NewRawNodeWPrefix creates a RawNode with the hash function
+// specified in prefix.
+func NewRawNodeWPrefix(data []byte, prefix cid.Prefix) (*RawNode, error) {
+	prefix.Codec = cid.Raw
+	if prefix.Version == 0 {
+		prefix.Version = 1
+	}
+	c, err := prefix.Sum(data)
+	if err != nil {
+		return nil, err
+	}
+	blk, err := blocks.NewBlockWithCid(data, c)
+	if err != nil {
+		return nil, err
+	}
+	return &RawNode{blk}, nil
+}
+
 func (rn *RawNode) Links() []*node.Link {
 	return nil
 }