fix: web3 rpc api returns wrong block gas limit (#782)

* Problem: web3 rpc api returns wrong block gas limit

Closes: #777

Solution:
- pass in specific block height to the query

* Apply suggestions from code review

* changelog

CHANGELOG.md

@@ -45,6 +45,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * (feemarket) [tharsis#770](https://github.com/tharsis/ethermint/pull/770) Enable fee market (EIP1559) by default.
 * (rpc) [tharsis#769](https://github.com/tharsis/ethermint/pull/769) Fix default Ethereum signer for JSON-RPC.
+* (rpc) [tharsis#782](https://github.com/tharsis/ethermint/pull/782) Fix wrong block gas limit returned by JSON-RPC.
 
 ## [v0.8.0] - 2021-11-17
 

rpc/ethereum/backend/backend.go

@@ -429,7 +429,7 @@ func (e *EVMBackend) EthBlockFromTendermint(
 
 	validatorAddr := common.BytesToAddress(addr)
 
-	gasLimit, err := types.BlockMaxGasFromConsensusParams(ctx, e.clientCtx)
+	gasLimit, err := types.BlockMaxGasFromConsensusParams(ctx, e.clientCtx, block.Height)
 	if err != nil {
 		e.logger.Error("failed to query consensus params", "error", err.Error())
 	}

rpc/ethereum/types/utils.go

@@ -64,9 +64,9 @@ func EthHeaderFromTendermint(header tmtypes.Header, bloom ethtypes.Bloom, baseFe
 	}
 }
 
-// BlockMaxGasFromConsensusParams returns the gas limit for the latest block from the chain consensus params.
-func BlockMaxGasFromConsensusParams(ctx context.Context, clientCtx client.Context) (int64, error) {
-	resConsParams, err := clientCtx.Client.ConsensusParams(ctx, nil)
+// BlockMaxGasFromConsensusParams returns the gas limit for the current block from the chain consensus params.
+func BlockMaxGasFromConsensusParams(goCtx context.Context, clientCtx client.Context, blockHeight int64) (int64, error) {
+	resConsParams, err := clientCtx.Client.ConsensusParams(goCtx, &blockHeight)
 	if err != nil {
 		return int64(^uint32(0)), err
 	}