[FAB-4163] Nil dereference in configtxgen

When attempting to generate a genesis block while failing to specify an
orderer section, the result was a nil point dereference.

This CR fixes the dereference by protecting it behind a nil check, and
updates the tool logic to check for the existence of the section, and
print an error and exit if it is not present.

Change-Id: Id768f23d7e138fd7c8ca90889e805975fdf44bec
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

common/configtx/tool/configtxgen/main.go

@@ -44,6 +44,9 @@ var logger = flogging.MustGetLogger("common/configtx/tool")
 func doOutputBlock(config *genesisconfig.Profile, channelID string, outputBlock string) error {
 	pgen := provisional.New(config)
 	logger.Info("Generating genesis block")
+	if config.Orderer == nil {
+		return fmt.Errorf("config does not contain an Orderers section, necessary for all config blocks, aborting")
+	}
 	if config.Consortiums == nil {
 		logger.Warning("Genesis block does not contain a consortiums group definition.  This block cannot be used for orderer bootstrap.")
 	}

common/configtx/tool/configtxgen/main_test.go

@@ -51,6 +51,16 @@ func TestInspectBlock(t *testing.T) {
 	assert.NoError(t, doInspectBlock(blockDest), "Good block inspection request")
 }
 
+func TestMissingOrdererSection(t *testing.T) {
+	blockDest := tmpDir + string(os.PathSeparator) + "block"
+
+	factory.InitFactories(nil)
+	config := genesisconfig.Load(genesisconfig.SampleInsecureProfile)
+	config.Orderer = nil
+
+	assert.Error(t, doOutputBlock(config, "foo", blockDest), "Missing orderer section")
+}
+
 func TestInspectConfigTx(t *testing.T) {
 	configTxDest := tmpDir + string(os.PathSeparator) + "configtx"
 

common/configtx/tool/provisional/provisional.go

@@ -88,7 +88,6 @@ func New(conf *genesisconfig.Profile) Generator {
 			// Chain Config Types
 			config.DefaultHashingAlgorithm(),
 			config.DefaultBlockDataHashingStructure(),
-			config.TemplateOrdererAddresses(conf.Orderer.Addresses), // TODO, move to conf.Channel when it exists
 
 			// Default policies
 			policies.TemplateImplicitMetaAnyPolicy([]string{}, configvaluesmsp.ReadersPolicyKey),
@@ -99,6 +98,9 @@ func New(conf *genesisconfig.Profile) Generator {
 
 	if conf.Orderer != nil {
 		bs.ordererGroups = []*cb.ConfigGroup{
+			// Orderer addresses
+			config.TemplateOrdererAddresses(conf.Orderer.Addresses),
+
 			// Orderer Config Types
 			config.TemplateConsensusType(conf.Orderer.OrdererType),
 			config.TemplateBatchSize(&ab.BatchSize{