chaincode.go

/*
Copyright IBM Corp. 2016 All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

		 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// Package shim provides APIs for the chaincode to access its state
// variables, transaction context and call other chaincodes.
package shim

import (
	"bytes"
	"errors"
	"flag"
	"fmt"
	"io"
	"os"
	"strconv"
	"strings"

	"github.com/golang/protobuf/proto"
	"github.com/golang/protobuf/ptypes/timestamp"
	"github.com/hyperledger/fabric/core/chaincode/shim/crypto/attr"
	"github.com/hyperledger/fabric/core/chaincode/shim/crypto/ecdsa"
	"github.com/hyperledger/fabric/core/comm"
	pb "github.com/hyperledger/fabric/protos"
	"github.com/op/go-logging"
	"github.com/spf13/viper"
	"golang.org/x/net/context"
	"google.golang.org/grpc"
)

// Logger for the shim package.
var chaincodeLogger = logging.MustGetLogger("shim")

// Handler to shim that handles all control logic.
var handler *Handler

// ChaincodeStub is an object passed to chaincode for shim side handling of
// APIs.
type ChaincodeStub struct {
	TxID            string
	securityContext *pb.ChaincodeSecurityContext
	chaincodeEvent  *pb.ChaincodeEvent
	args            [][]byte
}

// Peer address derived from command line or env var
var peerAddress string

// Start is the entry point for chaincodes bootstrap. It is not an API for
// chaincodes.
func Start(cc Chaincode) error {
	// If Start() is called, we assume this is a standalone chaincode and set
	// up formatted logging.
	format := logging.MustStringFormatter("%{time:15:04:05.000} [%{module}] %{level:.4s} : %{message}")
	backend := logging.NewLogBackend(os.Stderr, "", 0)
	backendFormatter := logging.NewBackendFormatter(backend, format)
	logging.SetBackend(backendFormatter).SetLevel(logging.Level(shimLoggingLevel), "shim")

	viper.SetEnvPrefix("CORE")
	viper.AutomaticEnv()
	replacer := strings.NewReplacer(".", "_")
	viper.SetEnvKeyReplacer(replacer)

	flag.StringVar(&peerAddress, "peer.address", "", "peer address")

	flag.Parse()

	chaincodeLogger.Debugf("Peer address: %s", getPeerAddress())

	// Establish connection with validating peer
	clientConn, err := newPeerClientConnection()
	if err != nil {
		chaincodeLogger.Errorf("Error trying to connect to local peer: %s", err)
		return fmt.Errorf("Error trying to connect to local peer: %s", err)
	}

	chaincodeLogger.Debugf("os.Args returns: %s", os.Args)

	chaincodeSupportClient := pb.NewChaincodeSupportClient(clientConn)

	// Establish stream with validating peer
	stream, err := chaincodeSupportClient.Register(context.Background())
	if err != nil {
		return fmt.Errorf("Error chatting with leader at address=%s:  %s", getPeerAddress(), err)
	}

	chaincodename := viper.GetString("chaincode.id.name")
	if chaincodename == "" {
		return fmt.Errorf("Error chaincode id not provided")
	}
	err = chatWithPeer(chaincodename, stream, cc)

	return err
}

// StartInProc is an entry point for system chaincodes bootstrap. It is not an
// API for chaincodes.
func StartInProc(env []string, args []string, cc Chaincode, recv <-chan *pb.ChaincodeMessage, send chan<- *pb.ChaincodeMessage) error {
	logging.SetLevel(logging.DEBUG, "chaincode")
	chaincodeLogger.Debugf("in proc %v", args)

	var chaincodename string
	for _, v := range env {
		if strings.Index(v, "CORE_CHAINCODE_ID_NAME=") == 0 {
			p := strings.SplitAfter(v, "CORE_CHAINCODE_ID_NAME=")
			chaincodename = p[1]
			break
		}
	}
	if chaincodename == "" {
		return fmt.Errorf("Error chaincode id not provided")
	}
	chaincodeLogger.Debugf("starting chat with peer using name=%s", chaincodename)
	stream := newInProcStream(recv, send)
	err := chatWithPeer(chaincodename, stream, cc)
	return err
}

func getPeerAddress() string {
	if peerAddress != "" {
		return peerAddress
	}

	if peerAddress = viper.GetString("peer.address"); peerAddress == "" {
		chaincodeLogger.Fatalf("peer.address not configured, can't connect to peer")
	}

	return peerAddress
}

func newPeerClientConnection() (*grpc.ClientConn, error) {
	var peerAddress = getPeerAddress()
	if comm.TLSEnabled() {
		return comm.NewClientConnectionWithAddress(peerAddress, true, true, comm.InitTLSForPeer())
	}
	return comm.NewClientConnectionWithAddress(peerAddress, true, false, nil)
}

func chatWithPeer(chaincodename string, stream PeerChaincodeStream, cc Chaincode) error {

	// Create the shim handler responsible for all control logic
	handler = newChaincodeHandler(stream, cc)

	defer stream.CloseSend()
	// Send the ChaincodeID during register.
	chaincodeID := &pb.ChaincodeID{Name: chaincodename}
	payload, err := proto.Marshal(chaincodeID)
	if err != nil {
		return fmt.Errorf("Error marshalling chaincodeID during chaincode registration: %s", err)
	}
	// Register on the stream
	chaincodeLogger.Debugf("Registering.. sending %s", pb.ChaincodeMessage_REGISTER)
	handler.serialSend(&pb.ChaincodeMessage{Type: pb.ChaincodeMessage_REGISTER, Payload: payload})
	waitc := make(chan struct{})
	go func() {
		defer close(waitc)
		msgAvail := make(chan *pb.ChaincodeMessage)
		var nsInfo *nextStateInfo
		var in *pb.ChaincodeMessage
		recv := true
		for {
			in = nil
			err = nil
			nsInfo = nil
			if recv {
				recv = false
				go func() {
					var in2 *pb.ChaincodeMessage
					in2, err = stream.Recv()
					msgAvail <- in2
				}()
			}
			select {
			case in = <-msgAvail:
				if err == io.EOF {
					chaincodeLogger.Debugf("Received EOF, ending chaincode stream, %s", err)
					return
				} else if err != nil {
					chaincodeLogger.Errorf("Received error from server: %s, ending chaincode stream", err)
					return
				} else if in == nil {
					err = fmt.Errorf("Received nil message, ending chaincode stream")
					chaincodeLogger.Debug("Received nil message, ending chaincode stream")
					return
				}
				chaincodeLogger.Debugf("[%s]Received message %s from shim", shorttxid(in.Txid), in.Type.String())
				recv = true
			case nsInfo = <-handler.nextState:
				in = nsInfo.msg
				if in == nil {
					panic("nil msg")
				}
				chaincodeLogger.Debugf("[%s]Move state message %s", shorttxid(in.Txid), in.Type.String())
			}

			// Call FSM.handleMessage()
			err = handler.handleMessage(in)
			if err != nil {
				err = fmt.Errorf("Error handling message: %s", err)
				return
			}

			//keepalive messages are PONGs to the fabric's PINGs
			if (nsInfo != nil && nsInfo.sendToCC) || (in.Type == pb.ChaincodeMessage_KEEPALIVE) {
				if in.Type == pb.ChaincodeMessage_KEEPALIVE {
					chaincodeLogger.Debug("Sending KEEPALIVE response")
				} else {
					chaincodeLogger.Debugf("[%s]send state message %s", shorttxid(in.Txid), in.Type.String())
				}
				if err = handler.serialSend(in); err != nil {
					err = fmt.Errorf("Error sending %s: %s", in.Type.String(), err)
					return
				}
			}
		}
	}()
	<-waitc
	return err
}

// -- init stub ---
// ChaincodeInvocation functionality

func (stub *ChaincodeStub) init(txid string, secContext *pb.ChaincodeSecurityContext) {
	stub.TxID = txid
	stub.securityContext = secContext
	stub.args = [][]byte{}
	newCI := pb.ChaincodeInput{}
	err := proto.Unmarshal(secContext.Payload, &newCI)
	if err == nil {
		stub.args = newCI.Args
	} else {
		panic("Arguments cannot be unmarshalled.")
	}
}

func (stub *ChaincodeStub) GetTxID() string {
	return stub.TxID
}

// --------- Security functions ----------
//CHAINCODE SEC INTERFACE FUNCS TOBE IMPLEMENTED BY ANGELO

// ------------- Call Chaincode functions ---------------

// InvokeChaincode locally calls the specified chaincode `Invoke` using the
// same transaction context; that is, chaincode calling chaincode doesn't
// create a new transaction message.
func (stub *ChaincodeStub) InvokeChaincode(chaincodeName string, args [][]byte) ([]byte, error) {
	return handler.handleInvokeChaincode(chaincodeName, args, stub.TxID)
}

// QueryChaincode locally calls the specified chaincode `Query` using the
// same transaction context; that is, chaincode calling chaincode doesn't
// create a new transaction message.
func (stub *ChaincodeStub) QueryChaincode(chaincodeName string, args [][]byte) ([]byte, error) {
	return handler.handleQueryChaincode(chaincodeName, args, stub.TxID)
}

// --------- State functions ----------

// GetState returns the byte array value specified by the `key`.
func (stub *ChaincodeStub) GetState(key string) ([]byte, error) {
	return handler.handleGetState(key, stub.TxID)
}

// PutState writes the specified `value` and `key` into the ledger.
func (stub *ChaincodeStub) PutState(key string, value []byte) error {
	return handler.handlePutState(key, value, stub.TxID)
}

// DelState removes the specified `key` and its value from the ledger.
func (stub *ChaincodeStub) DelState(key string) error {
	return handler.handleDelState(key, stub.TxID)
}

//ReadCertAttribute is used to read an specific attribute from the transaction certificate, *attributeName* is passed as input parameter to this function.
// Example:
//  attrValue,error:=stub.ReadCertAttribute("position")
func (stub *ChaincodeStub) ReadCertAttribute(attributeName string) ([]byte, error) {
	attributesHandler, err := attr.NewAttributesHandlerImpl(stub)
	if err != nil {
		return nil, err
	}
	return attributesHandler.GetValue(attributeName)
}

//VerifyAttribute is used to verify if the transaction certificate has an attribute with name *attributeName* and value *attributeValue* which are the input parameters received by this function.
//Example:
//    containsAttr, error := stub.VerifyAttribute("position", "Software Engineer")
func (stub *ChaincodeStub) VerifyAttribute(attributeName string, attributeValue []byte) (bool, error) {
	attributesHandler, err := attr.NewAttributesHandlerImpl(stub)
	if err != nil {
		return false, err
	}
	return attributesHandler.VerifyAttribute(attributeName, attributeValue)
}

//VerifyAttributes does the same as VerifyAttribute but it checks for a list of attributes and their respective values instead of a single attribute/value pair
// Example:
//    containsAttrs, error:= stub.VerifyAttributes(&attr.Attribute{"position",  "Software Engineer"}, &attr.Attribute{"company", "ACompany"})
func (stub *ChaincodeStub) VerifyAttributes(attrs ...*attr.Attribute) (bool, error) {
	attributesHandler, err := attr.NewAttributesHandlerImpl(stub)
	if err != nil {
		return false, err
	}
	return attributesHandler.VerifyAttributes(attrs...)
}

// StateRangeQueryIterator allows a chaincode to iterate over a range of
// key/value pairs in the state.
type StateRangeQueryIterator struct {
	handler    *Handler
	uuid       string
	response   *pb.RangeQueryStateResponse
	currentLoc int
}

// RangeQueryState function can be invoked by a chaincode to query of a range
// of keys in the state. Assuming the startKey and endKey are in lexical order,
// an iterator will be returned that can be used to iterate over all keys
// between the startKey and endKey, inclusive. The order in which keys are
// returned by the iterator is random.
func (stub *ChaincodeStub) RangeQueryState(startKey, endKey string) (StateRangeQueryIteratorInterface, error) {
	response, err := handler.handleRangeQueryState(startKey, endKey, stub.TxID)
	if err != nil {
		return nil, err
	}
	return &StateRangeQueryIterator{handler, stub.TxID, response, 0}, nil
}

// HasNext returns true if the range query iterator contains additional keys
// and values.
func (iter *StateRangeQueryIterator) HasNext() bool {
	if iter.currentLoc < len(iter.response.KeysAndValues) || iter.response.HasMore {
		return true
	}
	return false
}

// Next returns the next key and value in the range query iterator.
func (iter *StateRangeQueryIterator) Next() (string, []byte, error) {
	if iter.currentLoc < len(iter.response.KeysAndValues) {
		keyValue := iter.response.KeysAndValues[iter.currentLoc]
		iter.currentLoc++
		return keyValue.Key, keyValue.Value, nil
	} else if !iter.response.HasMore {
		return "", nil, errors.New("No such key")
	} else {
		response, err := iter.handler.handleRangeQueryStateNext(iter.response.ID, iter.uuid)

		if err != nil {
			return "", nil, err
		}

		iter.currentLoc = 0
		iter.response = response
		keyValue := iter.response.KeysAndValues[iter.currentLoc]
		iter.currentLoc++
		return keyValue.Key, keyValue.Value, nil

	}
}

// Close closes the range query iterator. This should be called when done
// reading from the iterator to free up resources.
func (iter *StateRangeQueryIterator) Close() error {
	_, err := iter.handler.handleRangeQueryStateClose(iter.response.ID, iter.uuid)
	return err
}

func (stub *ChaincodeStub) GetArgs() [][]byte {
	return stub.args
}

func (stub *ChaincodeStub) GetStringArgs() []string {
	args := stub.GetArgs()
	strargs := make([]string, 0, len(args))
	for _, barg := range args {
		strargs = append(strargs, string(barg))
	}
	return strargs
}

// TABLE FUNCTIONALITY
// TODO More comments here with documentation

// Table Errors
var (
	// ErrTableNotFound if the specified table cannot be found
	ErrTableNotFound = errors.New("chaincode: Table not found")
)

// CreateTable creates a new table given the table name and column definitions
func (stub *ChaincodeStub) CreateTable(name string, columnDefinitions []*ColumnDefinition) error {

	_, err := stub.getTable(name)
	if err == nil {
		return fmt.Errorf("CreateTable operation failed. Table %s already exists.", name)
	}
	if err != ErrTableNotFound {
		return fmt.Errorf("CreateTable operation failed. %s", err)
	}

	if columnDefinitions == nil || len(columnDefinitions) == 0 {
		return errors.New("Invalid column definitions. Tables must contain at least one column.")
	}

	hasKey := false
	nameMap := make(map[string]bool)
	for i, definition := range columnDefinitions {

		// Check name
		if definition == nil {
			return fmt.Errorf("Column definition %d is invalid. Definition must not be nil.", i)
		}
		if len(definition.Name) == 0 {
			return fmt.Errorf("Column definition %d is invalid. Name must be 1 or more characters.", i)
		}
		if _, exists := nameMap[definition.Name]; exists {
			return fmt.Errorf("Invalid table. Table contains duplicate column name '%s'.", definition.Name)
		}
		nameMap[definition.Name] = true

		// Check type
		switch definition.Type {
		case ColumnDefinition_STRING:
		case ColumnDefinition_INT32:
		case ColumnDefinition_INT64:
		case ColumnDefinition_UINT32:
		case ColumnDefinition_UINT64:
		case ColumnDefinition_BYTES:
		case ColumnDefinition_BOOL:
		default:
			return fmt.Errorf("Column definition %s does not have a valid type.", definition.Name)
		}

		if definition.Key {
			hasKey = true
		}
	}

	if !hasKey {
		return errors.New("Inavlid table. One or more columns must be a key.")
	}

	table := &Table{name, columnDefinitions}
	tableBytes, err := proto.Marshal(table)
	if err != nil {
		return fmt.Errorf("Error marshalling table: %s", err)
	}
	tableNameKey, err := getTableNameKey(name)
	if err != nil {
		return fmt.Errorf("Error creating table key: %s", err)
	}
	err = stub.PutState(tableNameKey, tableBytes)
	if err != nil {
		return fmt.Errorf("Error inserting table in state: %s", err)
	}
	return nil
}

// GetTable returns the table for the specified table name or ErrTableNotFound
// if the table does not exist.
func (stub *ChaincodeStub) GetTable(tableName string) (*Table, error) {
	return stub.getTable(tableName)
}

// DeleteTable deletes an entire table and all associated rows.
func (stub *ChaincodeStub) DeleteTable(tableName string) error {
	tableNameKey, err := getTableNameKey(tableName)
	if err != nil {
		return err
	}

	// Delete rows
	iter, err := stub.RangeQueryState(tableNameKey+"1", tableNameKey+":")
	if err != nil {
		return fmt.Errorf("Error deleting table: %s", err)
	}
	defer iter.Close()
	for iter.HasNext() {
		key, _, err := iter.Next()
		if err != nil {
			return fmt.Errorf("Error deleting table: %s", err)
		}
		err = stub.DelState(key)
		if err != nil {
			return fmt.Errorf("Error deleting table: %s", err)
		}
	}

	return stub.DelState(tableNameKey)
}

// InsertRow inserts a new row into the specified table.
// Returns -
// true and no error if the row is successfully inserted.
// false and no error if a row already exists for the given key.
// false and a TableNotFoundError if the specified table name does not exist.
// false and an error if there is an unexpected error condition.
func (stub *ChaincodeStub) InsertRow(tableName string, row Row) (bool, error) {
	return stub.insertRowInternal(tableName, row, false)
}

// ReplaceRow updates the row in the specified table.
// Returns -
// true and no error if the row is successfully updated.
// false and no error if a row does not exist the given key.
// flase and a TableNotFoundError if the specified table name does not exist.
// false and an error if there is an unexpected error condition.
func (stub *ChaincodeStub) ReplaceRow(tableName string, row Row) (bool, error) {
	return stub.insertRowInternal(tableName, row, true)
}

// GetRow fetches a row from the specified table for the given key.
func (stub *ChaincodeStub) GetRow(tableName string, key []Column) (Row, error) {

	var row Row

	keyString, err := buildKeyString(tableName, key)
	if err != nil {
		return row, err
	}

	rowBytes, err := stub.GetState(keyString)
	if err != nil {
		return row, fmt.Errorf("Error fetching row from DB: %s", err)
	}

	err = proto.Unmarshal(rowBytes, &row)
	if err != nil {
		return row, fmt.Errorf("Error unmarshalling row: %s", err)
	}

	return row, nil

}

// GetRows returns multiple rows based on a partial key. For example, given table
// | A | B | C | D |
// where A, C and D are keys, GetRows can be called with [A, C] to return
// all rows that have A, C and any value for D as their key. GetRows could
// also be called with A only to return all rows that have A and any value
// for C and D as their key.
func (stub *ChaincodeStub) GetRows(tableName string, key []Column) (<-chan Row, error) {

	keyString, err := buildKeyString(tableName, key)
	if err != nil {
		return nil, err
	}

	table, err := stub.getTable(tableName)
	if err != nil {
		return nil, err
	}

	// Need to check for special case where table has a single column
	if len(table.GetColumnDefinitions()) < 2 && len(key) > 0 {

		row, err := stub.GetRow(tableName, key)
		if err != nil {
			return nil, err
		}
		rows := make(chan Row)
		go func() {
			rows <- row
			close(rows)
		}()
		return rows, nil
	}

	iter, err := stub.RangeQueryState(keyString+"1", keyString+":")
	if err != nil {
		return nil, fmt.Errorf("Error fetching rows: %s", err)
	}

	rows := make(chan Row)

	go func() {
		defer func() {
			recover()
		}()
		for iter.HasNext() {
			_, rowBytes, err := iter.Next()
			if err != nil {
				close(rows)
			}

			var row Row
			err = proto.Unmarshal(rowBytes, &row)
			if err != nil {
				close(rows)
			}

			rows <- row

		}
		close(rows)
	}()

	return rows, nil

}

// DeleteRow deletes the row for the given key from the specified table.
func (stub *ChaincodeStub) DeleteRow(tableName string, key []Column) error {

	keyString, err := buildKeyString(tableName, key)
	if err != nil {
		return err
	}

	err = stub.DelState(keyString)
	if err != nil {
		return fmt.Errorf("DeleteRow operation error. Error deleting row: %s", err)
	}

	return nil
}

// VerifySignature verifies the transaction signature and returns `true` if
// correct and `false` otherwise
func (stub *ChaincodeStub) VerifySignature(certificate, signature, message []byte) (bool, error) {
	// Instantiate a new SignatureVerifier
	sv := ecdsa.NewX509ECDSASignatureVerifier()

	// Verify the signature
	return sv.Verify(certificate, signature, message)
}

// GetCallerCertificate returns caller certificate
func (stub *ChaincodeStub) GetCallerCertificate() ([]byte, error) {
	return stub.securityContext.CallerCert, nil
}

// GetCallerMetadata returns caller metadata
func (stub *ChaincodeStub) GetCallerMetadata() ([]byte, error) {
	return stub.securityContext.Metadata, nil
}

// GetBinding returns the transaction binding
func (stub *ChaincodeStub) GetBinding() ([]byte, error) {
	return stub.securityContext.Binding, nil
}

// GetPayload returns transaction payload, which is a `ChaincodeSpec` defined
// in fabric/protos/chaincode.proto
func (stub *ChaincodeStub) GetPayload() ([]byte, error) {
	return stub.securityContext.Payload, nil
}

// GetTxTimestamp returns transaction created timestamp, which is currently
// taken from the peer receiving the transaction. Note that this timestamp
// may not be the same with the other peers' time.
func (stub *ChaincodeStub) GetTxTimestamp() (*timestamp.Timestamp, error) {
	return stub.securityContext.TxTimestamp, nil
}

func (stub *ChaincodeStub) getTable(tableName string) (*Table, error) {

	tableName, err := getTableNameKey(tableName)
	if err != nil {
		return nil, err
	}

	tableBytes, err := stub.GetState(tableName)
	if tableBytes == nil {
		return nil, ErrTableNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("Error fetching table: %s", err)
	}
	table := &Table{}
	err = proto.Unmarshal(tableBytes, table)
	if err != nil {
		return nil, fmt.Errorf("Error unmarshalling table: %s", err)
	}

	return table, nil
}

func validateTableName(name string) error {
	if len(name) == 0 {
		return errors.New("Inavlid table name. Table name must be 1 or more characters.")
	}

	return nil
}

func getTableNameKey(name string) (string, error) {
	err := validateTableName(name)
	if err != nil {
		return "", err
	}

	return strconv.Itoa(len(name)) + name, nil
}

func buildKeyString(tableName string, keys []Column) (string, error) {

	var keyBuffer bytes.Buffer

	tableNameKey, err := getTableNameKey(tableName)
	if err != nil {
		return "", err
	}

	keyBuffer.WriteString(tableNameKey)

	for _, key := range keys {

		var keyString string
		switch key.Value.(type) {
		case *Column_String_:
			keyString = key.GetString_()
		case *Column_Int32:
			// b := make([]byte, 4)
			// binary.LittleEndian.PutUint32(b, uint32(key.GetInt32()))
			// keyBuffer.Write(b)
			keyString = strconv.FormatInt(int64(key.GetInt32()), 10)
		case *Column_Int64:
			keyString = strconv.FormatInt(key.GetInt64(), 10)
		case *Column_Uint32:
			keyString = strconv.FormatUint(uint64(key.GetUint32()), 10)
		case *Column_Uint64:
			keyString = strconv.FormatUint(key.GetUint64(), 10)
		case *Column_Bytes:
			keyString = string(key.GetBytes())
		case *Column_Bool:
			keyString = strconv.FormatBool(key.GetBool())
		}

		keyBuffer.WriteString(strconv.Itoa(len(keyString)))
		keyBuffer.WriteString(keyString)
	}

	return keyBuffer.String(), nil
}

func getKeyAndVerifyRow(table Table, row Row) ([]Column, error) {

	var keys []Column

	if row.Columns == nil || len(row.Columns) != len(table.ColumnDefinitions) {
		return keys, fmt.Errorf("Table '%s' defines %d columns, but row has %d columns.",
			table.Name, len(table.ColumnDefinitions), len(row.Columns))
	}

	for i, column := range row.Columns {

		// Check types
		var expectedType bool
		switch column.Value.(type) {
		case *Column_String_:
			expectedType = table.ColumnDefinitions[i].Type == ColumnDefinition_STRING
		case *Column_Int32:
			expectedType = table.ColumnDefinitions[i].Type == ColumnDefinition_INT32
		case *Column_Int64:
			expectedType = table.ColumnDefinitions[i].Type == ColumnDefinition_INT64
		case *Column_Uint32:
			expectedType = table.ColumnDefinitions[i].Type == ColumnDefinition_UINT32
		case *Column_Uint64:
			expectedType = table.ColumnDefinitions[i].Type == ColumnDefinition_UINT64
		case *Column_Bytes:
			expectedType = table.ColumnDefinitions[i].Type == ColumnDefinition_BYTES
		case *Column_Bool:
			expectedType = table.ColumnDefinitions[i].Type == ColumnDefinition_BOOL
		default:
			expectedType = false
		}
		if !expectedType {
			return keys, fmt.Errorf("The type for table '%s', column '%s' is '%s', but the column in the row does not match.",
				table.Name, table.ColumnDefinitions[i].Name, table.ColumnDefinitions[i].Type)
		}

		if table.ColumnDefinitions[i].Key {
			keys = append(keys, *column)
		}

	}

	return keys, nil
}

func (stub *ChaincodeStub) isRowPresent(tableName string, key []Column) (bool, error) {
	keyString, err := buildKeyString(tableName, key)
	if err != nil {
		return false, err
	}
	rowBytes, err := stub.GetState(keyString)
	if err != nil {
		return false, fmt.Errorf("Error fetching row for key %s: %s", keyString, err)
	}
	if rowBytes != nil {
		return true, nil
	}
	return false, nil
}

// insertRowInternal inserts a new row into the specified table.
// Returns -
// true and no error if the row is successfully inserted.
// false and no error if a row already exists for the given key.
// false and a TableNotFoundError if the specified table name does not exist.
// false and an error if there is an unexpected error condition.
func (stub *ChaincodeStub) insertRowInternal(tableName string, row Row, update bool) (bool, error) {

	table, err := stub.getTable(tableName)
	if err != nil {
		return false, err
	}

	key, err := getKeyAndVerifyRow(*table, row)
	if err != nil {
		return false, err
	}

	present, err := stub.isRowPresent(tableName, key)
	if err != nil {
		return false, err
	}
	if (present && !update) || (!present && update) {
		return false, nil
	}

	rowBytes, err := proto.Marshal(&row)
	if err != nil {
		return false, fmt.Errorf("Error marshalling row: %s", err)
	}

	keyString, err := buildKeyString(tableName, key)
	if err != nil {
		return false, err
	}
	err = stub.PutState(keyString, rowBytes)
	if err != nil {
		return false, fmt.Errorf("Error inserting row in table %s: %s", tableName, err)
	}

	return true, nil
}

// ------------- ChaincodeEvent API ----------------------

// SetEvent saves the event to be sent when a transaction is made part of a block
func (stub *ChaincodeStub) SetEvent(name string, payload []byte) error {
	stub.chaincodeEvent = &pb.ChaincodeEvent{EventName: name, Payload: payload}
	return nil
}

// ------------- Logging Control and Chaincode Loggers ---------------

// As independent programs, Go language chaincodes can use any logging
// methodology they choose, from simple fmt.Printf() to os.Stdout, to
// decorated logs created by the author's favorite logging package. The
// chaincode "shim" interface, however, is defined by the Hyperledger fabric
// and implements its own logging methodology. This methodology currently
// includes severity-based logging control and a standard way of decorating
// the logs.
//
// The facilities defined here allow a Go language chaincode to control the
// logging level of its shim, and to create its own logs formatted
// consistently with, and temporally interleaved with the shim logs without
// any knowledge of the underlying implementation of the shim, and without any
// other package requirements. The lack of package requirements is especially
// important because even if the chaincode happened to explicitly use the same
// logging package as the shim, unless the chaincode is physically included as
// part of the hyperledger fabric source code tree it could actually end up
// using a distinct binary instance of the logging package, with different
// formats and severity levels than the binary package used by the shim.
//
// Another approach that might have been taken, and could potentially be taken
// in the future, would be for the chaincode to supply a logging object for
// the shim to use, rather than the other way around as implemented
// here. There would be some complexities associated with that approach, so
// for the moment we have chosen the simpler implementation below. The shim
// provides one or more abstract logging objects for the chaincode to use via
// the NewLogger() API, and allows the chaincode to control the severity level
// of shim logs using the SetLoggingLevel() API.

// LoggingLevel is an enumerated type of severity levels that control
// chaincode logging.
type LoggingLevel logging.Level

// These constants comprise the LoggingLevel enumeration
const (
	LogDebug    = LoggingLevel(logging.DEBUG)
	LogInfo     = LoggingLevel(logging.INFO)
	LogNotice   = LoggingLevel(logging.NOTICE)
	LogWarning  = LoggingLevel(logging.WARNING)
	LogError    = LoggingLevel(logging.ERROR)
	LogCritical = LoggingLevel(logging.CRITICAL)
)

var shimLoggingLevel = LogDebug // Necessary for correct initialization; See Start()

// SetLoggingLevel allows a Go language chaincode to set the logging level of
// its shim.
func SetLoggingLevel(level LoggingLevel) {
	shimLoggingLevel = level
	logging.SetLevel(logging.Level(level), "shim")
}

// LogLevel converts a case-insensitive string chosen from CRITICAL, ERROR,
// WARNING, NOTICE, INFO or DEBUG into an element of the LoggingLevel
// type. In the event of errors the level returned is LogError.
func LogLevel(levelString string) (LoggingLevel, error) {
	l, err := logging.LogLevel(levelString)
	level := LoggingLevel(l)
	if err != nil {
		level = LogError
	}
	return level, err
}

// ------------- Chaincode Loggers ---------------

// ChaincodeLogger is an abstraction of a logging object for use by
// chaincodes. These objects are created by the NewLogger API.
type ChaincodeLogger struct {
	logger *logging.Logger
}

// NewLogger allows a Go language chaincode to create one or more logging
// objects whose logs will be formatted consistently with, and temporally
// interleaved with the logs created by the shim interface. The logs created
// by this object can be distinguished from shim logs by the name provided,
// which will appear in the logs.
func NewLogger(name string) *ChaincodeLogger {
	return &ChaincodeLogger{logging.MustGetLogger(name)}
}

// SetLevel sets the logging level for a chaincode logger. Note that currently
// the levels are actually controlled by the name given when the logger is
// created, so loggers should be given unique names other than "shim".
func (c *ChaincodeLogger) SetLevel(level LoggingLevel) {
	logging.SetLevel(logging.Level(level), c.logger.Module)
}

// IsEnabledFor returns true if the logger is enabled to creates logs at the
// given logging level.
func (c *ChaincodeLogger) IsEnabledFor(level LoggingLevel) bool {
	return c.logger.IsEnabledFor(logging.Level(level))
}

// Debug logs will only appear if the ChaincodeLogger LoggingLevel is set to
// LogDebug.
func (c *ChaincodeLogger) Debug(args ...interface{}) {
	c.logger.Debug(args...)
}

// Info logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogInfo or LogDebug.
func (c *ChaincodeLogger) Info(args ...interface{}) {
	c.logger.Info(args...)
}

// Notice logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogNotice, LogInfo or LogDebug.
func (c *ChaincodeLogger) Notice(args ...interface{}) {
	c.logger.Notice(args...)
}

// Warning logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogWarning, LogNotice, LogInfo or LogDebug.
func (c *ChaincodeLogger) Warning(args ...interface{}) {
	c.logger.Warning(args...)
}

// Error logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogError, LogWarning, LogNotice, LogInfo or LogDebug.
func (c *ChaincodeLogger) Error(args ...interface{}) {
	c.logger.Error(args...)
}

// Critical logs always appear; They can not be disabled.
func (c *ChaincodeLogger) Critical(args ...interface{}) {
	c.logger.Critical(args...)
}

// Debugf logs will only appear if the ChaincodeLogger LoggingLevel is set to
// LogDebug.
func (c *ChaincodeLogger) Debugf(format string, args ...interface{}) {
	c.logger.Debugf(format, args...)
}

// Infof logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogInfo or LogDebug.
func (c *ChaincodeLogger) Infof(format string, args ...interface{}) {
	c.logger.Infof(format, args...)
}

// Noticef logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogNotice, LogInfo or LogDebug.
func (c *ChaincodeLogger) Noticef(format string, args ...interface{}) {
	c.logger.Noticef(format, args...)
}

// Warningf logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogWarning, LogNotice, LogInfo or LogDebug.
func (c *ChaincodeLogger) Warningf(format string, args ...interface{}) {
	c.logger.Warningf(format, args...)
}

// Errorf logs will appear if the ChaincodeLogger LoggingLevel is set to
// LogError, LogWarning, LogNotice, LogInfo or LogDebug.
func (c *ChaincodeLogger) Errorf(format string, args ...interface{}) {
	c.logger.Errorf(format, args...)
}

// Criticalf logs always appear; They can not be disabled.
func (c *ChaincodeLogger) Criticalf(format string, args ...interface{}) {
	c.logger.Criticalf(format, args...)
}