func verify(ps peer.Peerstore, r *dhtpb.Record) error {
v := make(record.Validator)
v["pk"] = record.PublicKeyValidator
p := peer.ID(r.GetAuthor())
pk := ps.PubKey(p)
if pk == nil {
return fmt.Errorf("do not have public key for %s", p)
}
if err := record.CheckRecordSig(r, pk); err != nil {
return err
}
if err := v.VerifyRecord(r); err != nil {
return err
}
return nil
}
// verifyRecordLocally attempts to verify a record. if we do not have the public
// key, we fail. we do not search the dht.
func (dht *IpfsDHT) verifyRecordLocally(r *pb.Record) error {
if len(r.Signature) > 0 {
// First, validate the signature
p := peer.ID(r.GetAuthor())
pk := dht.peerstore.PubKey(p)
if pk == nil {
return fmt.Errorf("do not have public key for %s", p)
}
if err := record.CheckRecordSig(r, pk); err != nil {
return err
}
}
return dht.Validator.VerifyRecord(r)
}
// verifyRecordOnline verifies a record, searching the DHT for the public key
// if necessary. The reason there is a distinction in the functions is that
// retrieving arbitrary public keys from the DHT as a result of passively
// receiving records (e.g. through a PUT_VALUE or ADD_PROVIDER) can cause a
// massive amplification attack on the dht. Use with care.
func (dht *IpfsDHT) verifyRecordOnline(ctx context.Context, r *pb.Record) error {
if len(r.Signature) > 0 {
// get the public key, search for it if necessary.
p := peer.ID(r.GetAuthor())
pk, err := dht.GetPublicKey(ctx, p)
if err != nil {
return err
}
err = record.CheckRecordSig(r, pk)
if err != nil {
return err
}
}
return dht.Validator.VerifyRecord(r)
}
// RecordBlobForSig returns the blob protected by the record signature
func RecordBlobForSig(r *pb.Record) []byte {
k := []byte(r.GetKey())
v := []byte(r.GetValue())
a := []byte(r.GetAuthor())
return bytes.Join([][]byte{k, v, a}, []byte{})
}
func (dht *IpfsDHT) checkLocalDatastore(k key.Key) (*pb.Record, error) {
log.Debugf("%s handleGetValue looking into ds", dht.self)
dskey := k.DsKey()
iVal, err := dht.datastore.Get(dskey)
log.Debugf("%s handleGetValue looking into ds GOT %v", dht.self, iVal)
if err == ds.ErrNotFound {
return nil, nil
}
// if we got an unexpected error, bail.
if err != nil {
return nil, err
}
// if we have the value, send it back
log.Debugf("%s handleGetValue success!", dht.self)
byts, ok := iVal.([]byte)
if !ok {
return nil, fmt.Errorf("datastore had non byte-slice value for %v", dskey)
}
rec := new(pb.Record)
err = proto.Unmarshal(byts, rec)
if err != nil {
log.Debug("Failed to unmarshal dht record from datastore")
return nil, err
}
// if its our record, dont bother checking the times on it
if peer.ID(rec.GetAuthor()) == dht.self {
return rec, nil
}
var recordIsBad bool
recvtime, err := u.ParseRFC3339(rec.GetTimeReceived())
if err != nil {
log.Info("either no receive time set on record, or it was invalid: ", err)
recordIsBad = true
}
if time.Now().Sub(recvtime) > MaxRecordAge {
log.Debug("old record found, tossing.")
recordIsBad = true
}
// NOTE: we do not verify the record here beyond checking these timestamps.
// we put the burden of checking the records on the requester as checking a record
// may be computationally expensive
if recordIsBad {
err := dht.datastore.Delete(dskey)
if err != nil {
log.Error("Failed to delete bad record from datastore: ", err)
}
return nil, nil // can treat this as not having the record at all
}
return rec, nil
}