changes to support xdpos2 protocol from block 0

consensus/XDPoS/engines/engine_v2/engine.go

@@ -188,7 +188,10 @@ func (x *XDPoS_v2) initial(chain consensus.ChainReader, header *types.Header) er
 			Signatures:        nil,
 			GapNumber:         header.Number.Uint64() - x.config.Gap,
 		}
-
+		// prevent overflow
+		if header.Number.Uint64() < x.config.Gap {
+			quorumCert.GapNumber = 0
+		}
 		// can not call processQC because round is equal to default
 		x.currentRound = 1
 		x.highestQuorumCert = quorumCert
@@ -207,6 +210,10 @@ func (x *XDPoS_v2) initial(chain consensus.ChainReader, header *types.Header) er
 
 	// Initial first v2 snapshot
 	lastGapNum := x.config.V2.SwitchBlock.Uint64() - x.config.Gap
+	// prevent overflow
+	if x.config.V2.SwitchBlock.Uint64() < x.config.Gap {
+		lastGapNum = 0
+	}
 	lastGapHeader := chain.GetHeaderByNumber(lastGapNum)
 
 	snap, _ := loadSnapshot(x.db, lastGapHeader.Hash())
@@ -839,6 +846,10 @@ func (x *XDPoS_v2) verifyQC(blockChainReader consensus.ChainReader, quorumCert *
 	}
 	epochSwitchNumber := epochInfo.EpochSwitchBlockInfo.Number.Uint64()
 	gapNumber := epochSwitchNumber - epochSwitchNumber%x.config.Epoch - x.config.Gap
+	// prevent overflow
+	if epochSwitchNumber-epochSwitchNumber%x.config.Epoch < x.config.Gap {
+		gapNumber = 0
+	}
 	if gapNumber != quorumCert.GapNumber {
 		log.Error("[verifyQC] QC gap number mismatch", "epochSwitchNumber", epochSwitchNumber, "BlockNum", quorumCert.ProposedBlockInfo.Number, "BlockInfoHash", quorumCert.ProposedBlockInfo.Hash, "Gap", quorumCert.GapNumber, "GapShouldBe", gapNumber)
 		return fmt.Errorf("gap number mismatch QC Gap %d, shouldBe %d", quorumCert.GapNumber, gapNumber)

consensus/XDPoS/engines/engine_v2/epochSwitch.go

@@ -51,6 +51,26 @@ func (x *XDPoS_v2) getEpochSwitchInfo(chain consensus.ChainReader, header *types
 	}
 	if isEpochSwitch {
 		log.Debug("[getEpochSwitchInfo] header is epoch switch", "hash", hash.Hex(), "number", h.Number.Uint64())
+		if h.Number.Uint64() == 0 {
+			log.Warn("[getEpochSwitchInfo] block 0, init epoch differently")
+			// handle genesis block differently as follows
+			masternodes := common.ExtractAddressFromBytes(h.Extra[32 : len(h.Extra)-65])
+			penalties := []common.Address{}
+			standbynodes := []common.Address{}
+			epochSwitchInfo := &types.EpochSwitchInfo{
+				Penalties:      penalties,
+				Standbynodes:   standbynodes,
+				Masternodes:    masternodes,
+				MasternodesLen: len(masternodes),
+				EpochSwitchBlockInfo: &types.BlockInfo{
+					Hash:   hash,
+					Number: h.Number,
+					Round:  0,
+				},
+			}
+			x.epochSwitches.Add(hash, epochSwitchInfo)
+			return epochSwitchInfo, nil
+		}
 		quorumCert, round, masternodes, err := x.getExtraFields(h)
 		if err != nil {
 			log.Error("[getEpochSwitchInfo] get extra field", "err", err, "number", h.Number.Uint64())

consensus/XDPoS/engines/engine_v2/snapshot.go

@@ -78,6 +78,10 @@ func (x *XDPoS_v2) getSnapshot(chain consensus.ChainReader, number uint64, isGap
 		gapBlockNum = number
 	} else {
 		gapBlockNum = number - number%x.config.Epoch - x.config.Gap
+		//prevent overflow
+		if number-number%x.config.Epoch < x.config.Gap {
+			gapBlockNum = 0
+		}
 	}
 
 	gapBlockHash := chain.GetHeaderByNumber(gapBlockNum).Hash()

consensus/XDPoS/engines/engine_v2/timeout.go

@@ -195,6 +195,10 @@ func (x *XDPoS_v2) sendTimeout(chain consensus.ChainReader) error {
 		// Notice this +1 is because we expect a block whos is the child of currentHeader
 		currentNumber := currentBlockHeader.Number.Uint64() + 1
 		gapNumber = currentNumber - currentNumber%x.config.Epoch - x.config.Gap
+		// prevent overflow
+		if currentNumber-currentNumber%x.config.Epoch < x.config.Gap {
+			gapNumber = 0
+		}
 		log.Debug("[sendTimeout] is epoch switch when sending out timeout message", "currentNumber", currentNumber, "gapNumber", gapNumber)
 	} else {
 		epochSwitchInfo, err := x.getEpochSwitchInfo(chain, currentBlockHeader, currentBlockHeader.Hash())
@@ -203,6 +207,10 @@ func (x *XDPoS_v2) sendTimeout(chain consensus.ChainReader) error {
 			return err
 		}
 		gapNumber = epochSwitchInfo.EpochSwitchBlockInfo.Number.Uint64() - epochSwitchInfo.EpochSwitchBlockInfo.Number.Uint64()%x.config.Epoch - x.config.Gap
+		// prevent overflow
+		if epochSwitchInfo.EpochSwitchBlockInfo.Number.Uint64()-epochSwitchInfo.EpochSwitchBlockInfo.Number.Uint64()%x.config.Epoch < x.config.Gap {
+			gapNumber = 0
+		}
 		log.Debug("[sendTimeout] non-epoch-switch block found its epoch block and calculated the gapNumber", "epochSwitchInfo.EpochSwitchBlockInfo.Number", epochSwitchInfo.EpochSwitchBlockInfo.Number.Uint64(), "gapNumber", gapNumber)
 	}
 

consensus/XDPoS/engines/engine_v2/vote.go

@@ -30,6 +30,10 @@ func (x *XDPoS_v2) sendVote(chainReader consensus.ChainReader, blockInfo *types.
 	}
 	epochSwitchNumber := epochSwitchInfo.EpochSwitchBlockInfo.Number.Uint64()
 	gapNumber := epochSwitchNumber - epochSwitchNumber%x.config.Epoch - x.config.Gap
+	// prevent overflow
+	if epochSwitchNumber-epochSwitchNumber%x.config.Epoch < x.config.Gap {
+		gapNumber = 0
+	}
 	signedHash, err := x.signSignature(types.VoteSigHash(&types.VoteForSign{
 		ProposedBlockInfo: blockInfo,
 		GapNumber:         gapNumber,

eth/hooks/engine_v2_hooks.go

@@ -224,6 +224,11 @@ func GetSigningTxCount(c *XDPoS.XDPoS, chain consensus.ChainReader, header *type
 	signers := make(map[common.Address]*contracts.RewardLog)
 	mapBlkHash := map[uint64]common.Hash{}
 
+	// prevent overflow
+	if number == 0 {
+		return signers, nil
+	}
+
 	data := make(map[common.Hash][]common.Address)
 	epochCount := 0
 	var masternodes []common.Address
@@ -259,6 +264,10 @@ func GetSigningTxCount(c *XDPoS.XDPoS, chain consensus.ChainReader, header *type
 			from := *tx.From()
 			data[blkHash] = append(data[blkHash], from)
 		}
+		// prevent overflow
+		if i == 0 {
+			return signers, nil
+		}
 	}
 
 	for i := startBlockNumber; i <= endBlockNumber; i++ {