dag: fix git plugin

License: MIT
Signed-off-by: Łukasz Magiera <magik6k@gmail.com>

plugin/plugins/git/git.go

@@ -2,12 +2,15 @@ package git
 
 import (
 	"compress/zlib"
+	"fmt"
 	"io"
+	"math"
 
 	"github.com/ipfs/go-ipfs/core/coredag"
 	"github.com/ipfs/go-ipfs/plugin"
 
 	"gx/ipfs/QmTprEaAA2A9bst5XH7exuyi5KzNMK3SEDNN8rBDnKWcUS/go-cid"
+	mh "gx/ipfs/QmU9a9NV9RdPNwZQDYd5uKsm6N6LJLSvLbywDDYFbaaC6P/go-multihash"
 	"gx/ipfs/QmYNyRZJBUYPNrLszFmrBrPJbsBh2vMsefz5gnDpB5M1P6/go-ipld-format"
 	git "gx/ipfs/Qma7Kuwun7w8SZphjEPDVxvGfetBkqdNGmigDA13sJdLex/go-ipld-git"
 )
@@ -44,7 +47,15 @@ func (*gitPlugin) RegisterInputEncParsers(iec coredag.InputEncParsers) error {
 	return nil
 }
 
-func parseRawGit(r io.Reader) ([]format.Node, error) {
+func parseRawGit(r io.Reader, mhType uint64, mhLen int) ([]format.Node, error) {
+	if mhType != math.MaxUint64 && mhType != mh.SHA1 {
+		return nil, fmt.Errorf("unsupported mhType %d", mhType)
+	}
+
+	if mhLen != -1 && mhLen != mh.DefaultLengths[mh.SHA1] {
+		return nil, fmt.Errorf("invalid mhLen %d", mhType)
+	}
+
 	nd, err := git.ParseObject(r)
 	if err != nil {
 		return nil, err
@@ -53,12 +64,12 @@ func parseRawGit(r io.Reader) ([]format.Node, error) {
 	return []format.Node{nd}, nil
 }
 
-func parseZlibGit(r io.Reader) ([]format.Node, error) {
+func parseZlibGit(r io.Reader, mhType uint64, mhLen int) ([]format.Node, error) {
 	rc, err := zlib.NewReader(r)
 	if err != nil {
 		return nil, err
 	}
 
 	defer rc.Close()
-	return parseRawGit(rc)
+	return parseRawGit(rc, mhType, mhLen)
 }