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routing.go
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routing.go
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package dht
import (
"bytes"
"context"
"fmt"
"sync"
"time"
"github.com/libp2p/go-libp2p-core/network"
"github.com/libp2p/go-libp2p-core/peer"
"github.com/libp2p/go-libp2p-core/peerstore"
"github.com/libp2p/go-libp2p-core/routing"
"github.com/ipfs/go-cid"
u "github.com/ipfs/go-ipfs-util"
"github.com/libp2p/go-libp2p-kad-dht/internal"
internalConfig "github.com/libp2p/go-libp2p-kad-dht/internal/config"
"github.com/libp2p/go-libp2p-kad-dht/qpeerset"
kb "github.com/libp2p/go-libp2p-kbucket"
record "github.com/libp2p/go-libp2p-record"
"github.com/multiformats/go-multihash"
)
// This file implements the Routing interface for the IpfsDHT struct.
// Basic Put/Get
// PutValue adds value corresponding to given Key.
// This is the top level "Store" operation of the DHT
func (dht *IpfsDHT) PutValue(ctx context.Context, key string, value []byte, opts ...routing.Option) (err error) {
if !dht.enableValues {
return routing.ErrNotSupported
}
logger.Debugw("putting value", "key", internal.LoggableRecordKeyString(key))
// don't even allow local users to put bad values.
if err := dht.Validator.Validate(key, value); err != nil {
return err
}
old, err := dht.getLocal(ctx, key)
if err != nil {
// Means something is wrong with the datastore.
return err
}
// Check if we have an old value that's not the same as the new one.
if old != nil && !bytes.Equal(old.GetValue(), value) {
// Check to see if the new one is better.
i, err := dht.Validator.Select(key, [][]byte{value, old.GetValue()})
if err != nil {
return err
}
if i != 0 {
return fmt.Errorf("can't replace a newer value with an older value")
}
}
rec := record.MakePutRecord(key, value)
rec.TimeReceived = u.FormatRFC3339(time.Now())
err = dht.putLocal(ctx, key, rec)
if err != nil {
return err
}
peers, err := dht.GetClosestPeers(ctx, key)
if err != nil {
return err
}
wg := sync.WaitGroup{}
for _, p := range peers {
wg.Add(1)
go func(p peer.ID) {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
defer wg.Done()
routing.PublishQueryEvent(ctx, &routing.QueryEvent{
Type: routing.Value,
ID: p,
})
err := dht.protoMessenger.PutValue(ctx, p, rec)
if err != nil {
logger.Debugf("failed putting value to peer: %s", err)
}
}(p)
}
wg.Wait()
return nil
}
// recvdVal stores a value and the peer from which we got the value.
type recvdVal struct {
Val []byte
From peer.ID
}
// GetValue searches for the value corresponding to given Key.
func (dht *IpfsDHT) GetValue(ctx context.Context, key string, opts ...routing.Option) (_ []byte, err error) {
if !dht.enableValues {
return nil, routing.ErrNotSupported
}
// apply defaultQuorum if relevant
var cfg routing.Options
if err := cfg.Apply(opts...); err != nil {
return nil, err
}
opts = append(opts, Quorum(internalConfig.GetQuorum(&cfg)))
responses, err := dht.SearchValue(ctx, key, opts...)
if err != nil {
return nil, err
}
var best []byte
for r := range responses {
best = r
}
if ctx.Err() != nil {
return best, ctx.Err()
}
if best == nil {
return nil, routing.ErrNotFound
}
logger.Debugf("GetValue %v %x", internal.LoggableRecordKeyString(key), best)
return best, nil
}
// SearchValue searches for the value corresponding to given Key and streams the results.
func (dht *IpfsDHT) SearchValue(ctx context.Context, key string, opts ...routing.Option) (<-chan []byte, error) {
if !dht.enableValues {
return nil, routing.ErrNotSupported
}
var cfg routing.Options
if err := cfg.Apply(opts...); err != nil {
return nil, err
}
responsesNeeded := 0
if !cfg.Offline {
responsesNeeded = internalConfig.GetQuorum(&cfg)
}
stopCh := make(chan struct{})
valCh, lookupRes := dht.getValues(ctx, key, stopCh)
out := make(chan []byte)
go func() {
defer close(out)
best, peersWithBest, aborted := dht.searchValueQuorum(ctx, key, valCh, stopCh, out, responsesNeeded)
if best == nil || aborted {
return
}
updatePeers := make([]peer.ID, 0, dht.bucketSize)
select {
case l := <-lookupRes:
if l == nil {
return
}
for _, p := range l.peers {
if _, ok := peersWithBest[p]; !ok {
updatePeers = append(updatePeers, p)
}
}
case <-ctx.Done():
return
}
dht.updatePeerValues(dht.Context(), key, best, updatePeers)
}()
return out, nil
}
func (dht *IpfsDHT) searchValueQuorum(ctx context.Context, key string, valCh <-chan recvdVal, stopCh chan struct{},
out chan<- []byte, nvals int) ([]byte, map[peer.ID]struct{}, bool) {
numResponses := 0
return dht.processValues(ctx, key, valCh,
func(ctx context.Context, v recvdVal, better bool) bool {
numResponses++
if better {
select {
case out <- v.Val:
case <-ctx.Done():
return false
}
}
if nvals > 0 && numResponses > nvals {
close(stopCh)
return true
}
return false
})
}
func (dht *IpfsDHT) processValues(ctx context.Context, key string, vals <-chan recvdVal,
newVal func(ctx context.Context, v recvdVal, better bool) bool) (best []byte, peersWithBest map[peer.ID]struct{}, aborted bool) {
loop:
for {
if aborted {
return
}
select {
case v, ok := <-vals:
if !ok {
break loop
}
// Select best value
if best != nil {
if bytes.Equal(best, v.Val) {
peersWithBest[v.From] = struct{}{}
aborted = newVal(ctx, v, false)
continue
}
sel, err := dht.Validator.Select(key, [][]byte{best, v.Val})
if err != nil {
logger.Warnw("failed to select best value", "key", internal.LoggableRecordKeyString(key), "error", err)
continue
}
if sel != 1 {
aborted = newVal(ctx, v, false)
continue
}
}
peersWithBest = make(map[peer.ID]struct{})
peersWithBest[v.From] = struct{}{}
best = v.Val
aborted = newVal(ctx, v, true)
case <-ctx.Done():
return
}
}
return
}
func (dht *IpfsDHT) updatePeerValues(ctx context.Context, key string, val []byte, peers []peer.ID) {
fixupRec := record.MakePutRecord(key, val)
for _, p := range peers {
go func(p peer.ID) {
//TODO: Is this possible?
if p == dht.self {
err := dht.putLocal(ctx, key, fixupRec)
if err != nil {
logger.Error("Error correcting local dht entry:", err)
}
return
}
ctx, cancel := context.WithTimeout(ctx, time.Second*30)
defer cancel()
err := dht.protoMessenger.PutValue(ctx, p, fixupRec)
if err != nil {
logger.Debug("Error correcting DHT entry: ", err)
}
}(p)
}
}
func (dht *IpfsDHT) getValues(ctx context.Context, key string, stopQuery chan struct{}) (<-chan recvdVal, <-chan *lookupWithFollowupResult) {
valCh := make(chan recvdVal, 1)
lookupResCh := make(chan *lookupWithFollowupResult, 1)
logger.Debugw("finding value", "key", internal.LoggableRecordKeyString(key))
if rec, err := dht.getLocal(ctx, key); rec != nil && err == nil {
select {
case valCh <- recvdVal{
Val: rec.GetValue(),
From: dht.self,
}:
case <-ctx.Done():
}
}
go func() {
defer close(valCh)
defer close(lookupResCh)
lookupRes, err := dht.runLookupWithFollowup(ctx, key,
func(ctx context.Context, p peer.ID) ([]*peer.AddrInfo, error) {
// For DHT query command
routing.PublishQueryEvent(ctx, &routing.QueryEvent{
Type: routing.SendingQuery,
ID: p,
})
rec, peers, err := dht.protoMessenger.GetValue(ctx, p, key)
if err != nil {
return nil, err
}
// For DHT query command
routing.PublishQueryEvent(ctx, &routing.QueryEvent{
Type: routing.PeerResponse,
ID: p,
Responses: peers,
})
if rec == nil {
return peers, nil
}
val := rec.GetValue()
if val == nil {
logger.Debug("received a nil record value")
return peers, nil
}
if err := dht.Validator.Validate(key, val); err != nil {
// make sure record is valid
logger.Debugw("received invalid record (discarded)", "error", err)
return peers, nil
}
// the record is present and valid, send it out for processing
select {
case valCh <- recvdVal{
Val: val,
From: p,
}:
case <-ctx.Done():
return nil, ctx.Err()
}
return peers, nil
},
func() bool {
select {
case <-stopQuery:
return true
default:
return false
}
},
)
if err != nil {
return
}
lookupResCh <- lookupRes
if ctx.Err() == nil {
dht.refreshRTIfNoShortcut(kb.ConvertKey(key), lookupRes)
}
}()
return valCh, lookupResCh
}
func (dht *IpfsDHT) refreshRTIfNoShortcut(key kb.ID, lookupRes *lookupWithFollowupResult) {
if lookupRes.completed {
// refresh the cpl for this key as the query was successful
dht.routingTable.ResetCplRefreshedAtForID(key, time.Now())
}
}
// Provider abstraction for indirect stores.
// Some DHTs store values directly, while an indirect store stores pointers to
// locations of the value, similarly to Coral and Mainline DHT.
// Provide makes this node announce that it can provide a value for the given key
func (dht *IpfsDHT) Provide(ctx context.Context, key cid.Cid, brdcst bool) (err error) {
if !dht.enableProviders {
return routing.ErrNotSupported
} else if !key.Defined() {
return fmt.Errorf("invalid cid: undefined")
}
keyMH := key.Hash()
logger.Debugw("providing", "cid", key, "mh", internal.LoggableProviderRecordBytes(keyMH))
// add self locally
dht.providerStore.AddProvider(ctx, keyMH, peer.AddrInfo{ID: dht.self})
if !brdcst {
return nil
}
closerCtx := ctx
if deadline, ok := ctx.Deadline(); ok {
now := time.Now()
timeout := deadline.Sub(now)
if timeout < 0 {
// timed out
return context.DeadlineExceeded
} else if timeout < 10*time.Second {
// Reserve 10% for the final put.
deadline = deadline.Add(-timeout / 10)
} else {
// Otherwise, reserve a second (we'll already be
// connected so this should be fast).
deadline = deadline.Add(-time.Second)
}
var cancel context.CancelFunc
closerCtx, cancel = context.WithDeadline(ctx, deadline)
defer cancel()
}
var exceededDeadline bool
peers, err := dht.GetClosestPeers(closerCtx, string(keyMH))
switch err {
case context.DeadlineExceeded:
// If the _inner_ deadline has been exceeded but the _outer_
// context is still fine, provide the value to the closest peers
// we managed to find, even if they're not the _actual_ closest peers.
if ctx.Err() != nil {
return ctx.Err()
}
exceededDeadline = true
case nil:
default:
return err
}
wg := sync.WaitGroup{}
for _, p := range peers {
wg.Add(1)
go func(p peer.ID) {
defer wg.Done()
logger.Debugf("putProvider(%s, %s)", internal.LoggableProviderRecordBytes(keyMH), p)
err := dht.protoMessenger.PutProvider(ctx, p, keyMH, dht.host)
if err != nil {
logger.Debug(err)
}
}(p)
}
wg.Wait()
if exceededDeadline {
return context.DeadlineExceeded
}
return ctx.Err()
}
// FindProviders searches until the context expires.
func (dht *IpfsDHT) FindProviders(ctx context.Context, c cid.Cid) ([]peer.AddrInfo, error) {
if !dht.enableProviders {
return nil, routing.ErrNotSupported
} else if !c.Defined() {
return nil, fmt.Errorf("invalid cid: undefined")
}
var providers []peer.AddrInfo
for p := range dht.FindProvidersAsync(ctx, c, dht.bucketSize) {
providers = append(providers, p)
}
return providers, nil
}
// FindProvidersAsync is the same thing as FindProviders, but returns a channel.
// Peers will be returned on the channel as soon as they are found, even before
// the search query completes. If count is zero then the query will run until it
// completes. Note: not reading from the returned channel may block the query
// from progressing.
func (dht *IpfsDHT) FindProvidersAsync(ctx context.Context, key cid.Cid, count int) <-chan peer.AddrInfo {
if !dht.enableProviders || !key.Defined() {
peerOut := make(chan peer.AddrInfo)
close(peerOut)
return peerOut
}
chSize := count
if count == 0 {
chSize = 1
}
peerOut := make(chan peer.AddrInfo, chSize)
keyMH := key.Hash()
logger.Debugw("finding providers", "cid", key, "mh", internal.LoggableProviderRecordBytes(keyMH))
go dht.findProvidersAsyncRoutine(ctx, keyMH, count, peerOut)
return peerOut
}
func (dht *IpfsDHT) findProvidersAsyncRoutine(ctx context.Context, key multihash.Multihash, count int, peerOut chan peer.AddrInfo) {
defer close(peerOut)
findAll := count == 0
var ps *peer.Set
if findAll {
ps = peer.NewSet()
} else {
ps = peer.NewLimitedSet(count)
}
provs, err := dht.providerStore.GetProviders(ctx, key)
if err != nil {
return
}
for _, p := range provs {
// NOTE: Assuming that this list of peers is unique
if ps.TryAdd(p.ID) {
select {
case peerOut <- p:
case <-ctx.Done():
return
}
}
// If we have enough peers locally, don't bother with remote RPC
// TODO: is this a DOS vector?
if !findAll && ps.Size() >= count {
return
}
}
lookupRes, err := dht.runLookupWithFollowup(ctx, string(key),
func(ctx context.Context, p peer.ID) ([]*peer.AddrInfo, error) {
// For DHT query command
routing.PublishQueryEvent(ctx, &routing.QueryEvent{
Type: routing.SendingQuery,
ID: p,
})
provs, closest, err := dht.protoMessenger.GetProviders(ctx, p, key)
if err != nil {
return nil, err
}
logger.Debugf("%d provider entries", len(provs))
// Add unique providers from request, up to 'count'
for _, prov := range provs {
dht.maybeAddAddrs(prov.ID, prov.Addrs, peerstore.TempAddrTTL)
logger.Debugf("got provider: %s", prov)
if ps.TryAdd(prov.ID) {
logger.Debugf("using provider: %s", prov)
select {
case peerOut <- *prov:
case <-ctx.Done():
logger.Debug("context timed out sending more providers")
return nil, ctx.Err()
}
}
if !findAll && ps.Size() >= count {
logger.Debugf("got enough providers (%d/%d)", ps.Size(), count)
return nil, nil
}
}
// Give closer peers back to the query to be queried
logger.Debugf("got closer peers: %d %s", len(closest), closest)
routing.PublishQueryEvent(ctx, &routing.QueryEvent{
Type: routing.PeerResponse,
ID: p,
Responses: closest,
})
return closest, nil
},
func() bool {
return !findAll && ps.Size() >= count
},
)
if err == nil && ctx.Err() == nil {
dht.refreshRTIfNoShortcut(kb.ConvertKey(string(key)), lookupRes)
}
}
// FindPeer searches for a peer with given ID.
func (dht *IpfsDHT) FindPeer(ctx context.Context, id peer.ID) (_ peer.AddrInfo, err error) {
if err := id.Validate(); err != nil {
return peer.AddrInfo{}, err
}
logger.Debugw("finding peer", "peer", id)
// Check if were already connected to them
if pi := dht.FindLocal(id); pi.ID != "" {
return pi, nil
}
lookupRes, err := dht.runLookupWithFollowup(ctx, string(id),
func(ctx context.Context, p peer.ID) ([]*peer.AddrInfo, error) {
// For DHT query command
routing.PublishQueryEvent(ctx, &routing.QueryEvent{
Type: routing.SendingQuery,
ID: p,
})
peers, err := dht.protoMessenger.GetClosestPeers(ctx, p, id)
if err != nil {
logger.Debugf("error getting closer peers: %s", err)
return nil, err
}
// For DHT query command
routing.PublishQueryEvent(ctx, &routing.QueryEvent{
Type: routing.PeerResponse,
ID: p,
Responses: peers,
})
return peers, err
},
func() bool {
return dht.host.Network().Connectedness(id) == network.Connected
},
)
if err != nil {
return peer.AddrInfo{}, err
}
dialedPeerDuringQuery := false
for i, p := range lookupRes.peers {
if p == id {
// Note: we consider PeerUnreachable to be a valid state because the peer may not support the DHT protocol
// and therefore the peer would fail the query. The fact that a peer that is returned can be a non-DHT
// server peer and is not identified as such is a bug.
dialedPeerDuringQuery = (lookupRes.state[i] == qpeerset.PeerQueried || lookupRes.state[i] == qpeerset.PeerUnreachable || lookupRes.state[i] == qpeerset.PeerWaiting)
break
}
}
// Return peer information if we tried to dial the peer during the query or we are (or recently were) connected
// to the peer.
connectedness := dht.host.Network().Connectedness(id)
if dialedPeerDuringQuery || connectedness == network.Connected || connectedness == network.CanConnect {
return dht.peerstore.PeerInfo(id), nil
}
return peer.AddrInfo{}, routing.ErrNotFound
}