1. Expire non-provider records older than MaxAge

2. Original publisher should republish putvalue records
3. Peers who receive a record will republish hourly

Author: aarshkshah1992

dht.go

@@ -53,6 +53,8 @@ type IpfsDHT struct {
 	routingTable *kb.RoutingTable // Array of routing tables for differently distanced nodes
 	providers    *providers.ProviderManager
 
+	nonProvRecordsManager *NonProvRecordsManager
+
 	birth time.Time // When this peer started up
 
 	Validator record.Validator
@@ -98,13 +100,15 @@ func New(ctx context.Context, h host.Host, options ...opts.Option) (*IpfsDHT, er
 	})
 
 	dht.proc.AddChild(dht.providers.Process())
+	dht.proc.AddChild(dht.nonProvRecordsManager.Process())
 	dht.Validator = cfg.Validator
 
 	if !cfg.Client {
 		for _, p := range cfg.Protocols {
 			h.SetStreamHandler(p, dht.handleNewStream)
 		}
 	}
+
 	return dht, nil
 }
 
@@ -156,6 +160,7 @@ func makeDHT(ctx context.Context, h host.Host, dstore ds.Batching, protocols []p
 	}
 
 	dht.ctx = dht.newContextWithLocalTags(ctx)
+	dht.nonProvRecordsManager = NewNonProvRecordsManager(ctx, dht, dstore)
 
 	return dht
 }

go.mod

@@ -21,6 +21,7 @@ require (
 	github.com/mr-tron/base58 v1.1.2
 	github.com/multiformats/go-multiaddr v0.0.4
 	github.com/multiformats/go-multiaddr-dns v0.0.2
+	github.com/multiformats/go-multihash v0.0.5
 	github.com/multiformats/go-multistream v0.1.0
 	github.com/stretchr/testify v1.3.0
 	github.com/whyrusleeping/base32 v0.0.0-20170828182744-c30ac30633cc

handlers.go

@@ -121,7 +121,7 @@ func (dht *IpfsDHT) checkLocalDatastore(k []byte) (*recpb.Record, error) {
 		recordIsBad = true
 	}
 
-	if time.Since(recvtime) > MaxRecordAge {
+	if time.Since(recvtime) > maxNonProvRecordAge {
 		logger.Debug("old record found, tossing.")
 		recordIsBad = true
 	}
@@ -396,3 +396,7 @@ func (dht *IpfsDHT) handleAddProvider(ctx context.Context, p peer.ID, pmes *pb.M
 func convertToDsKey(s []byte) ds.Key {
 	return ds.NewKey(base32.RawStdEncoding.EncodeToString(s))
 }
+
+func convertToOriginalKey(k string) ([]byte, error) {
+	return base32.RawStdEncoding.DecodeString(k)
+}

non_prov_records.go

@@ -0,0 +1,193 @@
+package dht
+
+import (
+	"context"
+	"math/rand"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/gogo/protobuf/proto"
+	ds "github.com/ipfs/go-datastore"
+	"github.com/ipfs/go-datastore/query"
+	u "github.com/ipfs/go-ipfs-util"
+	"github.com/jbenet/goprocess"
+	"github.com/jbenet/goprocess/context"
+	"github.com/libp2p/go-libp2p-kad-dht/providers"
+	recpb "github.com/libp2p/go-libp2p-record/pb"
+)
+
+// vars for cleaning up expired records
+var nonProvRecordCleanupInterval = time.Hour
+
+// maxNonProvRecordAge specifies the maximum time that any node will hold onto a record
+// from the time its received. This does not apply to any other forms of validity that
+// the record may contain.
+// For example, a record may contain an ipns entry with an EOL saying its valid
+// until the year 2020 (a great time in the future). For that record to stick around
+// it must be rebroadcasted more frequently than once every 'maxNonProvRecordAge'
+var maxNonProvRecordAge = time.Hour * 36
+
+// vars for republishing records
+var nonProvRecordRePublishInterval = 1 * time.Hour
+var nonProvRecordRePublishAge = 1 * time.Hour
+var enableRepublishJitter = true
+
+type NonProvRecordsManager struct {
+	dht *IpfsDHT
+	ctx context.Context
+
+	proc   goprocess.Process
+	dstore ds.Batching
+
+	cleanupInterval time.Duration // scan interval for expiring records
+
+	rePublishInterval time.Duration // scan interval for republishing records
+}
+
+func NewNonProvRecordsManager(ctx context.Context, dht *IpfsDHT, dstore ds.Batching) *NonProvRecordsManager {
+	m := new(NonProvRecordsManager)
+	m.dht = dht
+	m.ctx = ctx
+	m.dstore = dstore
+	m.proc = goprocessctx.WithContext(ctx)
+
+	// expire records beyond maxage
+	m.cleanupInterval = nonProvRecordCleanupInterval
+	m.proc.Go(m.expire)
+
+	// republish records older than prescribed age
+	m.rePublishInterval = nonProvRecordRePublishInterval
+	m.proc.Go(m.rePublish)
+
+	return m
+}
+
+func (m *NonProvRecordsManager) Process() goprocess.Process {
+	return m.proc
+}
+
+func (m *NonProvRecordsManager) rePublish(proc goprocess.Process) {
+	for {
+		var d = 0 * time.Minute
+		// minimizes the probability of all peers re-publishing together
+		// the first peer that re-publishes resets the receivedAt time on the record
+		// on all other peers that are among the K closest to the key, thus minimizing the number of republishes by other peers
+		if enableRepublishJitter {
+			d = time.Duration(rand.Intn(16)) * time.Minute
+		}
+
+		select {
+		case <-proc.Closing():
+			return
+		case <-time.After(m.rePublishInterval + d):
+		}
+
+		tFnc := func(t time.Time) bool {
+			return time.Since(t) > nonProvRecordRePublishAge && time.Since(t) < maxNonProvRecordAge
+		}
+
+		res, err := m.dstore.Query(query.Query{Filters: []query.Filter{&nonProvRecordFilter{tFnc}}})
+		if err != nil {
+			logger.Errorf("republish records proc: failed to run query against datastore, error is %s", err)
+			continue
+		}
+
+		var wg sync.WaitGroup
+		// semaphore to rate-limit number of concurrent PutValue calls
+		semaphore := make(chan struct{}, 5)
+		for {
+			e, ok := res.NextSync()
+			if !ok {
+				break
+			}
+
+			semaphore <- struct{}{}
+			wg.Add(1)
+			go func(e query.Result) {
+				defer func() {
+					<-semaphore
+					wg.Done()
+				}()
+
+				// unmarshal record
+				rec := new(recpb.Record)
+				if err := proto.Unmarshal(e.Value, rec); err != nil {
+					logger.Debugf("republish records proc: failed to unmarshal DHT record from datastore, error is %s", err)
+					return
+				}
+
+				// call put value
+				putCtx, cancel := context.WithTimeout(m.ctx, 2*time.Minute)
+				defer cancel()
+
+				// do not use e.key here as that represents the transformed version of the original key
+				// rec.GetKey is the original key sent by the peer who put this record to dht
+				if err := m.dht.PutValue(putCtx, string(rec.GetKey()), rec.Value); err != nil {
+					logger.Debugf("republish records proc: failed to re-publish to the network, error is %s", err)
+				}
+			}(e)
+		}
+		wg.Wait()
+	}
+}
+
+func (m *NonProvRecordsManager) expire(proc goprocess.Process) {
+	for {
+		select {
+		case <-proc.Closing():
+			return
+		case <-time.After(m.cleanupInterval):
+		}
+
+		tFnc := func(t time.Time) bool {
+			return time.Since(t) > maxNonProvRecordAge
+		}
+
+		res, err := m.dstore.Query(query.Query{Filters: []query.Filter{&nonProvRecordFilter{tFnc}}})
+		if err != nil {
+			logger.Errorf("expire records proc: failed to run query against datastore, error is %s", err)
+			continue
+		}
+
+		for {
+			e, ok := res.NextSync()
+			if !ok {
+				break
+			}
+			if err := m.dstore.Delete(ds.RawKey(e.Key)); err != nil {
+				logger.Errorf("expire records proc: failed to delete key %s from datastore, error is %s", e.Key, err)
+			}
+		}
+	}
+}
+
+type timeFilterFnc = func(t time.Time) bool
+
+type nonProvRecordFilter struct {
+	tFnc timeFilterFnc
+}
+
+func (f *nonProvRecordFilter) Filter(e query.Entry) bool {
+	// unmarshal record
+	rec := new(recpb.Record)
+	if err := proto.Unmarshal(e.Value, rec); err != nil {
+		logger.Debugf("expire records filter: failed to unmarshal DHT record from datastore, error is %s", err)
+		return false
+	}
+
+	// should not be a provider record
+	if strings.HasPrefix(e.Key, providers.ProvidersKeyPrefix) {
+		return false
+	}
+
+	// parse received time
+	t, err := u.ParseRFC3339(rec.TimeReceived)
+	if err != nil {
+		logger.Debugf("expire records filter: failed to parse time in DHT record, error is %s", err)
+		return false
+	}
+
+	// apply the time filter fnc to the received time
+	return f.tFnc(t)
+}