rpc: fix cumulative gas (#662)

* rpc: fix cumulative gas

* changelog

CHANGELOG.md

@@ -50,6 +50,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 ### Bug Fixes
 
 * (evm) [\#661](https://github.com/cosmos/ethermint/pull/661) Set nonce to the EVM account on genesis initialization.
+* (rpc) [\#648](https://github.com/cosmos/ethermint/issues/648) Fix block cumulative gas used value.
 * (evm) [\#621](https://github.com/cosmos/ethermint/issues/621) EVM `GenesisAccount` fields now share the same format as the auth module `Account`.
 * (evm) [\#618](https://github.com/cosmos/ethermint/issues/618) Add missing EVM `Context` `GetHash` field that retrieves a the header hash from a given block height.
 * (app) [\#617](https://github.com/cosmos/ethermint/issues/617) Fix genesis export functionality.

rpc/namespaces/eth/api.go

@@ -677,6 +677,11 @@ func (api *PublicEthereumAPI) GetTransactionReceipt(hash common.Hash) (map[strin
 		return nil, err
 	}
 
+	cumulativeGasUsed := uint64(tx.TxResult.GasUsed)
+	if tx.Index != 0 {
+		cumulativeGasUsed += rpctypes.GetBlockCumulativeGas(api.clientCtx.Codec, block.Block, int(tx.Index))
+	}
+
 	// Set status codes based on tx result
 	var status hexutil.Uint
 	if tx.TxResult.IsOK() {
@@ -699,7 +704,7 @@ func (api *PublicEthereumAPI) GetTransactionReceipt(hash common.Hash) (map[strin
 	receipt := map[string]interface{}{
 		// Consensus fields: These fields are defined by the Yellow Paper
 		"status":            status,
-		"cumulativeGasUsed": nil, // ignore until needed
+		"cumulativeGasUsed": hexutil.Uint64(cumulativeGasUsed),
 		"logsBloom":         data.Bloom,
 		"logs":              data.Logs,
 
@@ -715,7 +720,7 @@ func (api *PublicEthereumAPI) GetTransactionReceipt(hash common.Hash) (map[strin
 		"blockNumber":      hexutil.Uint64(tx.Height),
 		"transactionIndex": hexutil.Uint64(tx.Index),
 
-		// sender and receiver (contract or EOA) addreses
+		// sender and receiver (contract or EOA) addresses
 		"from": from,
 		"to":   ethTx.To(),
 	}

rpc/types/utils.go

@@ -10,7 +10,9 @@ import (
 	tmtypes "github.com/tendermint/tendermint/types"
 
 	clientcontext "github.com/cosmos/cosmos-sdk/client/context"
+	"github.com/cosmos/cosmos-sdk/codec"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
+	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 
 	"github.com/cosmos/ethermint/crypto/ethsecp256k1"
 	evmtypes "github.com/cosmos/ethermint/x/evm/types"
@@ -189,3 +191,26 @@ func GetKeyByAddress(keys []ethsecp256k1.PrivKey, address common.Address) (key *
 	}
 	return nil, false
 }
+
+// GetBlockCumulativeGas returns the cumulative gas used on a block up to a given
+// transaction index. The returned gas used includes the gas from both the SDK and
+// EVM module transactions.
+func GetBlockCumulativeGas(cdc *codec.Codec, block *tmtypes.Block, idx int) uint64 {
+	var gasUsed uint64
+	txDecoder := evmtypes.TxDecoder(cdc)
+
+	for i := 0; i < idx && i < len(block.Txs[i]); i++ {
+		txi, err := txDecoder(block.Txs[i])
+		if err != nil {
+			continue
+		}
+
+		switch tx := txi.(type) {
+		case authtypes.StdTx:
+			gasUsed += tx.GetGas()
+		case evmtypes.MsgEthereumTx:
+			gasUsed += tx.GetGas()
+		}
+	}
+	return gasUsed
+}