raft: handle 'MsgTransferLeader' in follower

raft/raft.go

@@ -590,11 +590,6 @@ func (r *raft) Step(m pb.Message) error {
 		}
 		return nil
 	}
-	if m.Type == pb.MsgTransferLeader {
-		if r.state != StateLeader {
-			r.logger.Debugf("%x [term %d state %v] ignoring MsgTransferLeader to %x", r.id, r.Term, r.state, m.From)
-		}
-	}
 
 	switch {
 	case m.Term == 0:
@@ -874,6 +869,13 @@ func stepFollower(r *raft, m pb.Message) {
 				r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.From, m.LogTerm, m.Index, r.Term)
 			r.send(pb.Message{To: m.From, Type: pb.MsgVoteResp, Reject: true})
 		}
+	case pb.MsgTransferLeader:
+		if r.lead == None {
+			r.logger.Infof("%x no leader at term %d; dropping leader transfer msg", r.id, r.Term)
+			return
+		}
+		m.To = r.lead
+		r.send(m)
 	case pb.MsgTimeoutNow:
 		r.logger.Infof("%x [term %d] received MsgTimeoutNow from %x and starts an election to get leadership.", r.id, r.Term, m.From)
 		r.campaign(campaignTransfer)

raft/util.go

@@ -48,7 +48,7 @@ func max(a, b uint64) uint64 {
 
 func IsLocalMsg(msgt pb.MessageType) bool {
 	return msgt == pb.MsgHup || msgt == pb.MsgBeat || msgt == pb.MsgUnreachable ||
-		msgt == pb.MsgSnapStatus || msgt == pb.MsgCheckQuorum || msgt == pb.MsgTransferLeader
+		msgt == pb.MsgSnapStatus || msgt == pb.MsgCheckQuorum
 }
 
 func IsResponseMsg(msgt pb.MessageType) bool {