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ledger.go
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ledger.go
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/*
Copyright SecureKey Technologies Inc. All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
// Package ledger enables ledger queries on specified channel on a Fabric network.
// An application that requires ledger queries from multiple channels should create a separate
// instance of the ledger client for each channel. Ledger client supports the following queries:
// QueryInfo, QueryBlock, QueryBlockByHash, QueryBlockByTxID, QueryTransaction and QueryConfig.
//
// Basic Flow:
// 1) Prepare channel context
// 2) Create ledger client
// 3) Query ledger
package ledger
import (
reqContext "context"
"math/rand"
"time"
"github.com/golang/protobuf/proto"
"github.com/hyperledger/fabric-sdk-go/pkg/client/common/discovery"
"github.com/hyperledger/fabric-sdk-go/pkg/client/common/filter"
"github.com/hyperledger/fabric-sdk-go/pkg/client/common/verifier"
"github.com/hyperledger/fabric-sdk-go/pkg/common/errors/status"
"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/context"
"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/fab"
"github.com/hyperledger/fabric-sdk-go/pkg/fab/chconfig"
"github.com/hyperledger/fabric-sdk-go/third_party/github.com/hyperledger/fabric/protos/common"
pb "github.com/hyperledger/fabric-sdk-go/third_party/github.com/hyperledger/fabric/protos/peer"
contextImpl "github.com/hyperledger/fabric-sdk-go/pkg/context"
"github.com/hyperledger/fabric-sdk-go/pkg/fab/channel"
"github.com/pkg/errors"
)
// Client enables ledger queries on a Fabric network.
type Client struct {
ctx context.Channel
filter fab.TargetFilter
ledger *channel.Ledger
verifier channel.ResponseVerifier
discovery fab.DiscoveryService
}
// mspFilter is default filter
type mspFilter struct {
mspID string
}
// Accept returns true if this peer is to be included in the target list
func (f *mspFilter) Accept(peer fab.Peer) bool {
return peer.MSPID() == f.mspID
}
// New returns a ledger client instance. A ledger client instance provides a handler to query various info on specified channel.
// An application that requires interaction with multiple channels should create a separate
// instance of the ledger client for each channel. Ledger client supports specific queries only.
func New(channelProvider context.ChannelProvider, opts ...ClientOption) (*Client, error) {
channelContext, err := channelProvider()
if err != nil {
return nil, err
}
if channelContext.ChannelService() == nil {
return nil, errors.New("channel service not initialized")
}
membership, err := channelContext.ChannelService().Membership()
if err != nil {
return nil, errors.WithMessage(err, "membership creation failed")
}
ledger, err := channel.NewLedger(channelContext.ChannelID())
if err != nil {
return nil, err
}
ledgerFilter := filter.NewEndpointFilter(channelContext, filter.LedgerQuery)
discoveryService, err := channelContext.ChannelService().Discovery()
if err != nil {
return nil, err
}
// Apply filter to discovery service
discovery := discovery.NewDiscoveryFilterService(discoveryService, ledgerFilter)
ledgerClient := Client{
ctx: channelContext,
ledger: ledger,
verifier: &verifier.Signature{Membership: membership},
discovery: discovery,
}
for _, opt := range opts {
err := opt(&ledgerClient)
if err != nil {
return nil, err
}
}
// check if target filter was set - if not set the default
if ledgerClient.filter == nil {
// Default target filter is based on user msp
if channelContext.Identifier().MSPID == "" {
return nil, errors.New("mspID not available in user context")
}
filter := &mspFilter{mspID: channelContext.Identifier().MSPID}
ledgerClient.filter = filter
}
return &ledgerClient, nil
}
// QueryInfo queries for various useful blockchain information on this channel such as block height and current block hash.
// Parameters:
// options are optional request options
//
// Returns:
// blockchain information
func (c *Client) QueryInfo(options ...RequestOption) (*fab.BlockchainInfoResponse, error) {
targets, opts, err := c.prepareRequestParams(options...)
if err != nil {
return nil, errors.WithMessage(err, "QueryInfo failed to prepare request parameters")
}
reqCtx, cancel := c.createRequestContext(opts)
defer cancel()
responses, err := c.ledger.QueryInfo(reqCtx, peersToTxnProcessors(targets), c.verifier)
if err != nil && len(responses) == 0 {
return nil, errors.WithMessage(err, "QueryInfo failed")
}
if len(responses) < opts.MinTargets {
return nil, errors.Errorf("Number of responses %d is less than MinTargets %d. Targets: %v, Error: %s", len(responses), opts.MinTargets, targets, err)
}
response := responses[0]
maxHeight := response.BCI.Height
for i, r := range responses {
if i == 0 {
continue
}
// Match one with highest block height,
if r.BCI.Height > maxHeight {
response = r
maxHeight = r.BCI.Height
}
}
return response, nil
}
// QueryBlockByHash queries the ledger for block by block hash.
// Parameters:
// blockHash is required block hash
// options hold optional request options
//
// Returns:
// block information
func (c *Client) QueryBlockByHash(blockHash []byte, options ...RequestOption) (*common.Block, error) {
targets, opts, err := c.prepareRequestParams(options...)
if err != nil {
return nil, errors.WithMessage(err, "QueryBlockByHash failed to prepare request parameters")
}
reqCtx, cancel := c.createRequestContext(opts)
defer cancel()
responses, err := c.ledger.QueryBlockByHash(reqCtx, blockHash, peersToTxnProcessors(targets), c.verifier)
if err != nil && len(responses) == 0 {
return nil, errors.WithMessage(err, "QueryBlockByHash failed")
}
return matchBlockData(responses, opts.MinTargets)
}
// QueryBlockByTxID queries for block which contains a transaction.
// Parameters:
// txID is required transaction ID
// options hold optional request options
//
// Returns:
// block information
func (c *Client) QueryBlockByTxID(txID fab.TransactionID, options ...RequestOption) (*common.Block, error) {
targets, opts, err := c.prepareRequestParams(options...)
if err != nil {
return nil, errors.WithMessage(err, "QueryBlockByTxID failed to prepare request parameters")
}
reqCtx, cancel := c.createRequestContext(opts)
defer cancel()
responses, err := c.ledger.QueryBlockByTxID(reqCtx, txID, peersToTxnProcessors(targets), c.verifier)
if err != nil && len(responses) == 0 {
return nil, errors.WithMessage(err, "QueryBlockByTxID failed")
}
return matchBlockData(responses, opts.MinTargets)
}
// QueryBlock queries the ledger for Block by block number.
// Parameters:
// blockNumber is required block number(ID)
// options hold optional request options
//
// Returns:
// block information
func (c *Client) QueryBlock(blockNumber uint64, options ...RequestOption) (*common.Block, error) {
targets, opts, err := c.prepareRequestParams(options...)
if err != nil {
return nil, errors.WithMessage(err, "QueryBlock failed to prepare request parameters")
}
reqCtx, cancel := c.createRequestContext(opts)
defer cancel()
responses, err := c.ledger.QueryBlock(reqCtx, blockNumber, peersToTxnProcessors(targets), c.verifier)
if err != nil && len(responses) == 0 {
return nil, errors.WithMessage(err, "QueryBlock failed")
}
return matchBlockData(responses, opts.MinTargets)
}
func (c *Client) prepareRequestParams(options ...RequestOption) ([]fab.Peer, *requestOptions, error) {
opts, err := c.prepareRequestOpts(options...)
if err != nil {
return nil, nil, errors.WithMessage(err, "failed to get opts")
}
targets, err := c.calculateTargets(opts)
if err != nil {
return nil, nil, errors.WithMessage(err, "failed to determine target peers")
}
return targets, &opts, nil
}
func matchBlockData(responses []*common.Block, minTargets int) (*common.Block, error) {
if len(responses) < minTargets {
return nil, errors.Errorf("Number of responses %d is less than MinTargets %d", len(responses), minTargets)
}
response := responses[0]
for i, r := range responses {
if i == 0 {
continue
}
// Block data has to match
if !proto.Equal(response.Data, r.Data) {
return nil, errors.New("Block data does not match")
}
}
return response, nil
}
// QueryTransaction queries the ledger for processed transaction by transaction ID.
// Parameters:
// txID is required transaction ID
// options hold optional request options
//
// Returns:
// processed transaction information
func (c *Client) QueryTransaction(transactionID fab.TransactionID, options ...RequestOption) (*pb.ProcessedTransaction, error) {
targets, opts, err := c.prepareRequestParams(options...)
if err != nil {
return nil, errors.WithMessage(err, "QueryTransaction failed to prepare request parameters")
}
reqCtx, cancel := c.createRequestContext(opts)
defer cancel()
responses, err := c.ledger.QueryTransaction(reqCtx, transactionID, peersToTxnProcessors(targets), c.verifier)
if err != nil && len(responses) == 0 {
return nil, errors.WithMessage(err, "QueryTransaction failed")
}
if len(responses) < opts.MinTargets {
return nil, errors.Errorf("QueryTransaction: Number of responses %d is less than MinTargets %d", len(responses), opts.MinTargets)
}
response := responses[0]
for i, r := range responses {
if i == 0 {
continue
}
// All payloads have to match
if !proto.Equal(response, r) {
return nil, errors.New("Payloads for QueryTransaction do not match")
}
}
return response, nil
}
// QueryConfig queries for channel configuration.
// Parameters:
// options hold optional request options
//
// Returns:
// channel configuration information
func (c *Client) QueryConfig(options ...RequestOption) (fab.ChannelCfg, error) {
targets, opts, err := c.prepareRequestParams(options...)
if err != nil {
return nil, errors.WithMessage(err, "QueryConfig failed to prepare request parameters")
}
reqCtx, cancel := c.createRequestContext(opts)
defer cancel()
channelConfig, err := chconfig.New(c.ctx.ChannelID(), chconfig.WithPeers(targets), chconfig.WithMinResponses(opts.MinTargets))
if err != nil {
return nil, errors.WithMessage(err, "QueryConfig failed")
}
return channelConfig.Query(reqCtx)
}
//prepareRequestOpts Reads Opts from Option array
func (c *Client) prepareRequestOpts(options ...RequestOption) (requestOptions, error) {
opts := requestOptions{}
for _, option := range options {
err := option(c.ctx, &opts)
if err != nil {
return opts, errors.WithMessage(err, "Failed to read request opts")
}
}
// Set defaults for max targets
if opts.MaxTargets == 0 {
opts.MaxTargets = maxTargets
}
// Set defaults for min targets/matches
if opts.MinTargets == 0 {
opts.MinTargets = minTargets
}
if opts.MinTargets > opts.MaxTargets {
opts.MaxTargets = opts.MinTargets
}
return opts, nil
}
// calculateTargets calculates targets based on targets and filter
func (c *Client) calculateTargets(opts requestOptions) ([]fab.Peer, error) {
if opts.Targets != nil && opts.TargetFilter != nil {
return nil, errors.New("If targets are provided, filter cannot be provided")
}
targets := opts.Targets
targetFilter := opts.TargetFilter
var err error
if targets == nil {
// Retrieve targets from discovery
targets, err = c.discovery.GetPeers()
if err != nil {
return nil, err
}
if targetFilter == nil {
targetFilter = c.filter
}
}
if targetFilter != nil {
targets = filterTargets(targets, targetFilter)
}
if len(targets) == 0 {
return nil, errors.WithStack(status.New(status.ClientStatus, status.NoPeersFound.ToInt32(), "no targets available", nil))
}
if len(targets) < opts.MinTargets {
return nil, errors.Errorf("Error getting minimum number of targets. %d available, %d required", len(targets), opts.MinTargets)
}
// Calculate number of targets required
numOfTargets := opts.MaxTargets
if len(targets) < opts.MaxTargets {
numOfTargets = len(targets)
}
// Shuffle to randomize
shuffle(targets)
return targets[:numOfTargets], nil
}
//createRequestContext creates request context for grpc
func (c *Client) createRequestContext(opts *requestOptions) (reqContext.Context, reqContext.CancelFunc) {
if opts.Timeouts == nil {
opts.Timeouts = make(map[fab.TimeoutType]time.Duration)
}
if opts.Timeouts[fab.PeerResponse] == 0 {
opts.Timeouts[fab.PeerResponse] = c.ctx.EndpointConfig().Timeout(fab.PeerResponse)
}
return contextImpl.NewRequest(c.ctx, contextImpl.WithTimeout(opts.Timeouts[fab.PeerResponse]), contextImpl.WithParent(opts.ParentContext))
}
// filterTargets is helper method to filter peers
func filterTargets(peers []fab.Peer, filter fab.TargetFilter) []fab.Peer {
if filter == nil {
return peers
}
filteredPeers := []fab.Peer{}
for _, peer := range peers {
if filter.Accept(peer) {
filteredPeers = append(filteredPeers, peer)
}
}
return filteredPeers
}
// peersToTxnProcessors converts a slice of Peers to a slice of ProposalProcessors
func peersToTxnProcessors(peers []fab.Peer) []fab.ProposalProcessor {
tpp := make([]fab.ProposalProcessor, len(peers))
for i := range peers {
tpp[i] = peers[i]
}
return tpp
}
func shuffle(a []fab.Peer) {
for i := range a {
j := rand.Intn(i + 1)
a[i], a[j] = a[j], a[i]
}
}