fix: eth_feeHistory reward values cannot be nil (evmos#970)

* eth_feeHistory reward values cannot be nil

* removed reward when rewardPercentiles is not specified

* fix lint

* refactor and fix typos

* add changelog

Co-authored-by: Freddy Caceres <freddy.caceres@crypto.com>

CHANGELOG.md

@@ -83,6 +83,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (rpc) [tharsis#900](https://github.com/tharsis/ethermint/pull/900) newPendingTransactions filter return ethereum tx hash.
 * (rpc) [tharsis#933](https://github.com/tharsis/ethermint/pull/933) Fix newPendingTransactions subscription deadlock when a Websocket client exits without unsubscribing and the node errors.
 * (rpc) [#955](https://github.com/tharsis/ethermint/pull/955) Fix websocket server push duplicated messages to subscriber.
+* (rpc) [#970](https://github.com/tharsis/ethermint/pull/970) Fix unexpected nil reward values on `eth_feeHistory` response
 
 ## [v0.9.0] - 2021-12-01
 

rpc/ethereum/backend/feebackend.go

@@ -115,6 +115,7 @@ func (e *EVMBackend) processBlock(
  return nil
 }
 
+// FeeHistory returns data relevant for fee estimation based on the specified range of blocks.
 func (e *EVMBackend) FeeHistory(
  userBlockCount rpc.DecimalOrHex, // number blocks to fetch, maximum is 100
  lastBlock rpc.BlockNumber, // the block to start search , to oldest
@@ -145,13 +146,16 @@ func (e *EVMBackend) FeeHistory(
 
  // prepare space
  reward := make([][]*hexutil.Big, blockCount)
- rewardcount := len(rewardPercentiles)
+ rewardCount := len(rewardPercentiles)
  for i := 0; i < int(blockCount); i++ {
- reward[i] = make([]*hexutil.Big, rewardcount)
+ reward[i] = make([]*hexutil.Big, rewardCount)
  }
  thisBaseFee := make([]*hexutil.Big, blockCount)
  thisGasUsedRatio := make([]float64, blockCount)
 
+ // rewards should only be calculated if reward percentiles were included
+ calculateRewards := rewardCount != 0
+
  // fetch block
  for blockID := blockStart; blockID < blockEnd; blockID++ {
  index := int32(blockID - blockStart)
@@ -174,25 +178,34 @@ func (e *EVMBackend) FeeHistory(
  return nil, err
  }
 
- onefeehistory := rpctypes.OneFeeHistory{}
- err = e.processBlock(tendermintblock, &ethBlock, rewardPercentiles, tendermintBlockResult, &onefeehistory)
+ oneFeeHistory := rpctypes.OneFeeHistory{}
+ err = e.processBlock(tendermintblock, &ethBlock, rewardPercentiles, tendermintBlockResult, &oneFeeHistory)
  if err != nil {
  return nil, err
  }
 
  // copy
- thisBaseFee[index] = (*hexutil.Big)(onefeehistory.BaseFee)
- thisGasUsedRatio[index] = onefeehistory.GasUsedRatio
- for j := 0; j < rewardcount; j++ {
- reward[index][j] = (*hexutil.Big)(onefeehistory.Reward[j])
+ thisBaseFee[index] = (*hexutil.Big)(oneFeeHistory.BaseFee)
+ thisGasUsedRatio[index] = oneFeeHistory.GasUsedRatio
+ if calculateRewards {
+ for j := 0; j < rewardCount; j++ {
+ reward[index][j] = (*hexutil.Big)(oneFeeHistory.Reward[j])
+ if reward[index][j] == nil {
+ reward[index][j] = (*hexutil.Big)(big.NewInt(0))
+ }
+ }
  }
  }
 
  feeHistory := rpctypes.FeeHistoryResult{
  OldestBlock: oldestBlock,
- Reward: reward,
  BaseFee: thisBaseFee,
  GasUsedRatio: thisGasUsedRatio,
  }
+
+ if calculateRewards {
+ feeHistory.Reward = reward
+ }
+
  return &feeHistory, nil
 }