[FAB-8025] proto_encode/decode configtxlator opts

Currently, configtxlator only exposes its proto encoding/decoding
functionality through a REST interface.  Although this is generically
useful for applications written in other programming languages, it makes
CLI usage painfully dependant on curl.

This CR simply allows configtxlator to be run in a CLI fashion without
starting up the REST server.

Change-Id: Ie02a690271e6e0de95e11187c59c4ab04bde7eaa
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

Author: Jason Yellick

common/tools/configtxlator/main.go

@@ -18,12 +18,18 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"os"
+	"reflect"
 
 	"github.com/hyperledger/fabric/common/tools/configtxlator/metadata"
 	"github.com/hyperledger/fabric/common/tools/configtxlator/rest"
+	"github.com/hyperledger/fabric/common/tools/protolator"
+
+	"github.com/golang/protobuf/proto"
 	"github.com/op/go-logging"
+	"github.com/pkg/errors"
 	"gopkg.in/alecthomas/kingpin.v2"
 )
 
@@ -37,6 +43,16 @@ var (
 	hostname = start.Flag("hostname", "The hostname or IP on which the REST server will listen").Default("0.0.0.0").String()
 	port     = start.Flag("port", "The port on which the REST server will listen").Default("7059").Int()
 
+	protoEncode       = app.Command("proto_encode", "Converts a JSON document to protobuf.")
+	protoEncodeType   = protoEncode.Flag("type", "The type of protobuf structure to encode to.  For example, 'common.Config'.").Required().String()
+	protoEncodeSource = protoEncode.Flag("input", "A file containing the JSON document.").Default(os.Stdin.Name()).File()
+	protoEncodeDest   = protoEncode.Flag("output", "A file to write the output to.").Default(os.Stdout.Name()).OpenFile(os.O_RDWR|os.O_CREATE, 0600)
+
+	protoDecode       = app.Command("proto_decode", "Converts a proto message to JSON.")
+	protoDecodeType   = protoDecode.Flag("type", "The type of protobuf structure to decode from.  For example, 'common.Config'.").Required().String()
+	protoDecodeSource = protoDecode.Flag("input", "A file containing the proto message.").Default(os.Stdin.Name()).File()
+	protoDecodeDest   = protoDecode.Flag("output", "A file to write the JSON document to.").Default(os.Stdout.Name()).OpenFile(os.O_RDWR|os.O_CREATE, 0600)
+
 	version = app.Command("version", "Show version information")
 )
 
@@ -46,7 +62,21 @@ func main() {
 	// "start" command
 	case start.FullCommand():
 		startServer(fmt.Sprintf("%s:%d", *hostname, *port))
-
+	// "proto_encode" command
+	case protoEncode.FullCommand():
+		defer (*protoEncodeSource).Close()
+		defer (*protoEncodeDest).Close()
+		err := encodeProto(*protoEncodeType, *protoEncodeSource, *protoEncodeDest)
+		if err != nil {
+			app.Fatalf("Error decoding: %s", err)
+		}
+	case protoDecode.FullCommand():
+		defer (*protoDecodeSource).Close()
+		defer (*protoDecodeDest).Close()
+		err := decodeProto(*protoDecodeType, *protoDecodeSource, *protoDecodeDest)
+		if err != nil {
+			app.Fatalf("Error decoding: %s", err)
+		}
 	// "version" command
 	case version.FullCommand():
 		printVersion()
@@ -64,3 +94,53 @@ func startServer(address string) {
 func printVersion() {
 	fmt.Println(metadata.GetVersionInfo())
 }
+
+func encodeProto(msgName string, input, output *os.File) error {
+	msgType := proto.MessageType(msgName)
+	if msgType == nil {
+		return errors.Errorf("message of type %s unknown", msgType)
+	}
+	msg := reflect.New(msgType.Elem()).Interface().(proto.Message)
+
+	err := protolator.DeepUnmarshalJSON(input, msg)
+	if err != nil {
+		return errors.Wrapf(err, "error decoding input")
+	}
+
+	out, err := proto.Marshal(msg)
+	if err != nil {
+		return errors.Wrapf(err, "error marshaling")
+	}
+
+	_, err = output.Write(out)
+	if err != nil {
+		return errors.Wrapf(err, "error writing output")
+	}
+
+	return nil
+}
+
+func decodeProto(msgName string, input, output *os.File) error {
+	msgType := proto.MessageType(msgName)
+	if msgType == nil {
+		return errors.Errorf("message of type %s unknown", msgType)
+	}
+	msg := reflect.New(msgType.Elem()).Interface().(proto.Message)
+
+	in, err := ioutil.ReadAll(input)
+	if err != nil {
+		return errors.Wrapf(err, "error reading input")
+	}
+
+	err = proto.Unmarshal(in, msg)
+	if err != nil {
+		return errors.Wrapf(err, "error unmarshaling")
+	}
+
+	err = protolator.DeepMarshalJSON(output, msg)
+	if err != nil {
+		return errors.Wrapf(err, "error encoding output")
+	}
+
+	return nil
+}