[FAB-4467] Allow nil signer for creating envelope

The CreateSignedEnvelope function requires a signer as a parameter.  In
some instances, a signer is not available, or not required/desired.

This CR modifies the CreateSignedEnvelope function to accept a nil
signer, which will allow the function to proceed normally, simply
without performing the signing related operations.

Change-Id: I75dcba15c07cf4acb1f7fe293cd2271c9792460d
Signed-off-by: Jason Yellick <[email protected]>

Author: Jason Yellick

protos/utils/txutils.go

@@ -77,9 +77,14 @@ func GetEnvelopeFromBlock(data []byte) (*common.Envelope, error) {
 func CreateSignedEnvelope(txType common.HeaderType, channelID string, signer crypto.LocalSigner, dataMsg proto.Message, msgVersion int32, epoch uint64) (*common.Envelope, error) {
 	payloadChannelHeader := MakeChannelHeader(txType, msgVersion, channelID, epoch)
 
-	payloadSignatureHeader, err := signer.NewSignatureHeader()
-	if err != nil {
-		return nil, err
+	var err error
+	payloadSignatureHeader := &common.SignatureHeader{}
+
+	if signer != nil {
+		payloadSignatureHeader, err = signer.NewSignatureHeader()
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	data, err := proto.Marshal(dataMsg)
@@ -92,9 +97,12 @@ func CreateSignedEnvelope(txType common.HeaderType, channelID string, signer cry
 		Data:   data,
 	})
 
-	sig, err := signer.Sign(paylBytes)
-	if err != nil {
-		return nil, err
+	var sig []byte
+	if signer != nil {
+		sig, err = signer.Sign(paylBytes)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	return &common.Envelope{Payload: paylBytes, Signature: sig}, nil

protos/utils/txutils_test.go

@@ -256,6 +256,25 @@ func TestCreateSignedEnvelope(t *testing.T) {
 	assert.Error(t, err, "Expected sign error")
 }
 
+func TestCreateSignedEnvelopeNilSigner(t *testing.T) {
+	var env *cb.Envelope
+	channelID := "mychannelID"
+	msg := &cb.ConfigEnvelope{}
+
+	env, err := utils.CreateSignedEnvelope(cb.HeaderType_CONFIG, channelID,
+		nil, msg, int32(1), uint64(1))
+	assert.NoError(t, err, "Unexpected error creating signed envelope")
+	assert.NotNil(t, env, "Envelope should not be nil")
+	assert.Empty(t, env.Signature, "Signature should have been empty")
+	payload := &cb.Payload{}
+	err = proto.Unmarshal(env.Payload, payload)
+	assert.NoError(t, err, "Failed to unmarshal payload")
+	data := &cb.ConfigEnvelope{}
+	err = proto.Unmarshal(payload.Data, data)
+	assert.NoError(t, err, "Expected payload data to be a config envelope")
+	assert.Equal(t, msg, data, "Payload data does not match expected value")
+}
+
 func TestGetSignedProposal(t *testing.T) {
 	var signedProp *pb.SignedProposal
 	var err error