Factor out byte concatenation to utils

Per feedback from Kostas on

https://gerrit.hyperledger.org/r/#/c/3699/

This changeset factors out some byte concatenation which was easilly
generalizable.

Change-Id: I126286284eac5f1dd0b94a36573eb4c4bacb1302
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

common/util/utils.go

@@ -164,3 +164,21 @@ func GetTestOrgID() string {
 func GetSysCCVersion() string {
 	return metadata.Version
 }
+
+// ConcatenateBytes is useful for combining multiple arrays of bytes, especially for
+// signatures or digests over multiple fields
+func ConcatenateBytes(data ...[]byte) []byte {
+	finalLength := 0
+	for _, slice := range data {
+		finalLength += len(slice)
+	}
+	result := make([]byte, finalLength)
+	last := 0
+	for _, slice := range data {
+		for i := range slice {
+			result[i+last] = slice[i]
+		}
+		last += len(slice)
+	}
+	return result
+}

common/util/utils_test.go

@@ -118,3 +118,27 @@ func TestConcurrencyNotFail(t *testing.T) {
 		logger.Info("")
 	}
 }
+
+func TestMetadataSignatureBytesNormal(t *testing.T) {
+	first := []byte("first")
+	second := []byte("second")
+	third := []byte("third")
+
+	result := ConcatenateBytes(first, second, third)
+	expected := []byte("firstsecondthird")
+	if !bytes.Equal(result, expected) {
+		t.Errorf("Did not concatenate bytes correctly, expected %s, got %s", expected, result)
+	}
+}
+
+func TestMetadataSignatureBytesNil(t *testing.T) {
+	first := []byte("first")
+	second := []byte(nil)
+	third := []byte("third")
+
+	result := ConcatenateBytes(first, second, third)
+	expected := []byte("firstthird")
+	if !bytes.Equal(result, expected) {
+		t.Errorf("Did not concatenate bytes correctly, expected %s, got %s", expected, result)
+	}
+}

orderer/multichain/chainsupport.go

@@ -19,6 +19,7 @@ package multichain
 import (
 	"github.com/hyperledger/fabric/common/configtx"
 	"github.com/hyperledger/fabric/common/policies"
+	"github.com/hyperledger/fabric/common/util"
 	"github.com/hyperledger/fabric/orderer/common/blockcutter"
 	"github.com/hyperledger/fabric/orderer/common/broadcast"
 	"github.com/hyperledger/fabric/orderer/common/deliver"
@@ -193,19 +194,6 @@ func (cs *chainSupport) CreateNextBlock(messages []*cb.Envelope) *cb.Block {
 	return rawledger.CreateNextBlock(cs.ledger, messages)
 }
 
-// TODO, factor this out into common util code
-func metadataSignatureBytes(value []byte, sigHeader []byte, blockHeader []byte) []byte {
-	result := make([]byte, len(value)+len(sigHeader)+len(blockHeader))
-	last := 0
-	for _, slice := range [][]byte{value, sigHeader, blockHeader} {
-		for i := range slice {
-			result[i+last] = slice[i]
-		}
-		last += len(slice)
-	}
-	return result
-}
-
 func (cs *chainSupport) addBlockSignature(block *cb.Block) {
 	logger.Debugf("%+v", cs)
 	logger.Debugf("%+v", cs.signer)
@@ -217,7 +205,7 @@ func (cs *chainSupport) addBlockSignature(block *cb.Block) {
 	// information required beyond the fact that the metadata item is signed.
 	blockSignatureValue := []byte(nil)
 
-	blockSignature.Signature = cs.signer.Sign(metadataSignatureBytes(blockSignatureValue, blockSignature.SignatureHeader, block.Header.Bytes()))
+	blockSignature.Signature = cs.signer.Sign(util.ConcatenateBytes(blockSignatureValue, blockSignature.SignatureHeader, block.Header.Bytes()))
 
 	block.Metadata.Metadata[cb.BlockMetadataIndex_SIGNATURES] = utils.MarshalOrPanic(&cb.Metadata{
 		Value: blockSignatureValue,
@@ -240,7 +228,7 @@ func (cs *chainSupport) addLastConfigSignature(block *cb.Block) {
 
 	lastConfigValue := utils.MarshalOrPanic(&cb.LastConfiguration{Index: cs.lastConfiguration})
 
-	lastConfigSignature.Signature = cs.signer.Sign(metadataSignatureBytes(lastConfigValue, lastConfigSignature.SignatureHeader, block.Header.Bytes()))
+	lastConfigSignature.Signature = cs.signer.Sign(util.ConcatenateBytes(lastConfigValue, lastConfigSignature.SignatureHeader, block.Header.Bytes()))
 
 	block.Metadata.Metadata[cb.BlockMetadataIndex_LAST_CONFIGURATION] = utils.MarshalOrPanic(&cb.Metadata{
 		Value: lastConfigValue,

orderer/multichain/chainsupport_test.go

@@ -17,7 +17,6 @@ limitations under the License.
 package multichain
 
 import (
-	"bytes"
 	"reflect"
 	"testing"
 
@@ -87,18 +86,6 @@ func TestCommitConfig(t *testing.T) {
 	}
 }
 
-func TestMetadataSignatureBytes(t *testing.T) {
-	value := []byte("Value")
-	signatureHeader := []byte("SignatureHeader")
-	blockHeader := []byte("BlockHeader")
-
-	sigBytes := metadataSignatureBytes(value, signatureHeader, blockHeader)
-	expected := []byte("ValueSignatureHeaderBlockHeader")
-	if !bytes.Equal(sigBytes, expected) {
-		t.Errorf("Did not compute first signature bytes correctly, expected %s, got %s", expected, sigBytes)
-	}
-}
-
 func TestWriteBlockSignatures(t *testing.T) {
 	ml := &mockLedgerReadWriter{}
 	cm := &mockconfigtx.Manager{}

orderer/multichain/systemchain.go

@@ -194,7 +194,7 @@ func (sc *systemChain) authorize(configEnvelope *cb.ConfigurationEnvelope) cb.St
 			// Do not include the creation policy
 			continue
 		}
-		remainingBytes = append(remainingBytes, item.ConfigurationItem...)
+		remainingBytes = util.ConcatenateBytes(remainingBytes, item.ConfigurationItem)
 	}
 
 	configHash := util.ComputeCryptoHash(remainingBytes)

protos/common/signed_data.go

@@ -19,6 +19,8 @@ package common
 import (
 	"fmt"
 
+	"github.com/hyperledger/fabric/common/util"
+
 	"github.com/golang/protobuf/proto"
 )
 
@@ -53,7 +55,7 @@ func (sci *SignedConfigurationItem) AsSignedData() ([]*SignedData, error) {
 		}
 
 		result[i] = &SignedData{
-			Data:      append(sci.ConfigurationItem, configSig.SignatureHeader...),
+			Data:      util.ConcatenateBytes(sci.ConfigurationItem, configSig.SignatureHeader),
 			Identity:  sigHeader.Creator,
 			Signature: configSig.Signature,
 		}