fix: ignore errors that caused by gap to keep peer connection (bnb-ch…

…ain#49)

eth/downloader/skeleton.go

@@ -27,6 +27,7 @@ import (
  "github.com/ethereum/go-ethereum/common"
  "github.com/ethereum/go-ethereum/core/rawdb"
  "github.com/ethereum/go-ethereum/core/types"
+ "github.com/ethereum/go-ethereum/eth/etherror"
  "github.com/ethereum/go-ethereum/eth/protocols/eth"
  "github.com/ethereum/go-ethereum/ethdb"
  "github.com/ethereum/go-ethereum/log"
@@ -73,6 +74,9 @@ var errTerminated = errors.New("terminated")
 // with a new header, but it does not link up to the existing sync.
 var errReorgDenied = errors.New("non-forced head reorg denied")
 
+// maxBlockNumGapTolerance is the max gap tolerance by peer
+var maxBlockNumGapTolerance = uint64(30)
+
 func init() {
  // Tuning parameters is nice, but the scratch space must be assignable in
  // full to peers. It's a useless cornercase to support a dangling half-group.
@@ -786,25 +790,29 @@ func (s *skeleton) executeTask(peer *peerConnection, req *headerRequest) {
  case len(headers) == 0:
  // No headers were delivered, reject the response and reschedule
  peer.log.Debug("No headers delivered")
- res.Done <- errors.New("no headers delivered")
+ res.Done <- etherror.ErrNoHeadersDelivered
  s.scheduleRevertRequest(req)
 
  case headers[0].Number.Uint64() != req.head:
  // Header batch anchored at non-requested number
  peer.log.Debug("Invalid header response head", "have", headers[0].Number, "want", req.head)
- res.Done <- errors.New("invalid header batch anchor")
+ if req.head-headers[0].Number.Uint64() < maxBlockNumGapTolerance {
+ res.Done <- etherror.ErrHeaderBatchAnchorLow
+ } else {
+ res.Done <- etherror.ErrInvalidHeaderBatchAnchor
+ }
  s.scheduleRevertRequest(req)
 
  case req.head >= requestHeaders && len(headers) != requestHeaders:
  // Invalid number of non-genesis headers delivered, reject the response and reschedule
  peer.log.Debug("Invalid non-genesis header count", "have", len(headers), "want", requestHeaders)
- res.Done <- errors.New("not enough non-genesis headers delivered")
+ res.Done <- etherror.ErrNotEnoughNonGenesisHeaders
  s.scheduleRevertRequest(req)
 
  case req.head < requestHeaders && uint64(len(headers)) != req.head:
  // Invalid number of genesis headers delivered, reject the response and reschedule
  peer.log.Debug("Invalid genesis header count", "have", len(headers), "want", headers[0].Number.Uint64())
- res.Done <- errors.New("not enough genesis headers delivered")
+ res.Done <- etherror.ErrNotEnoughGenesisHeaders
  s.scheduleRevertRequest(req)
 
  default:
@@ -813,7 +821,7 @@ func (s *skeleton) executeTask(peer *peerConnection, req *headerRequest) {
  for i := 0; i < len(headers)-1; i++ {
  if headers[i].ParentHash != headers[i+1].Hash() {
  peer.log.Debug("Invalid hash progression", "index", i, "wantparenthash", headers[i].ParentHash, "haveparenthash", headers[i+1].Hash())
- res.Done <- errors.New("invalid hash progression")
+ res.Done <- etherror.ErrInvalidHashProgression
  s.scheduleRevertRequest(req)
  return
  }

eth/etherror/errors.go

@@ -0,0 +1,12 @@
+package etherror
+
+import "errors"
+
+var (
+ ErrNoHeadersDelivered = errors.New("no headers delivered")
+ ErrInvalidHeaderBatchAnchor = errors.New("invalid header batch anchor")
+ ErrNotEnoughNonGenesisHeaders = errors.New("not enough non-genesis headers delivered")
+ ErrNotEnoughGenesisHeaders = errors.New("not enough genesis headers delivered")
+ ErrInvalidHashProgression = errors.New("invalid hash progression")
+ ErrHeaderBatchAnchorLow = errors.New("header batch anchor is lower than requested")
+)

eth/protocols/eth/handler.go

@@ -17,13 +17,15 @@
 package eth
 
 import (
+ "errors"
  "fmt"
  "math/big"
  "time"
 
  "github.com/ethereum/go-ethereum/common"
  "github.com/ethereum/go-ethereum/core"
  "github.com/ethereum/go-ethereum/core/types"
+ "github.com/ethereum/go-ethereum/eth/etherror"
  "github.com/ethereum/go-ethereum/metrics"
  "github.com/ethereum/go-ethereum/p2p"
  "github.com/ethereum/go-ethereum/p2p/enode"
@@ -153,7 +155,19 @@ func nodeInfo(chain *core.BlockChain, network uint64) *NodeInfo {
 // connection is torn down.
 func Handle(backend Backend, peer *Peer) error {
  for {
- if err := handleMessage(backend, peer); err != nil {
+ err := handleMessage(backend, peer)
+ switch {
+ // TODO: currently no headers not ignored as it may leads to a dead peer not removing as expected
+ /*
+ case errors.Is(err, etherror.ErrNoHeadersDelivered):
+ // ignore no headers delivered
+ peer.Log().Warn("Message handling failed with no headers")
+ */
+ case errors.Is(err, etherror.ErrHeaderBatchAnchorLow):
+ // ignore lower header anchor within tolerance
+ peer.Log().Warn("Message handling failed with lower batch anchor")
+
+ case err != nil:
  peer.Log().Debug("Message handling failed in `eth`", "err", err)
  return err
  }