add eth_chainId JSON-RPC endpoint

pkg/eth/api.go

@@ -167,6 +167,19 @@ func (pea *PublicEthAPI) GetBlockByHash(ctx context.Context, hash common.Hash, f
 	return nil, err
 }
 
+// ChainId is the EIP-155 replay-protection chain id for the current ethereum chain config.
+func (api *PublicEthAPI) ChainId() (hexutil.Uint64, error) {
+	chainID := new(big.Int)
+	block, err := api.B.CurrentBlock()
+	if err != nil {
+		return 0, err
+	}
+	if config := api.B.Config.ChainConfig; config.IsEIP155(block.Number()) {
+		chainID = config.ChainID
+	}
+	return (hexutil.Uint64)(chainID.Uint64()), nil
+}
+
 /*
 
 Uncles

pkg/eth/backend.go

@@ -202,9 +202,9 @@ func (b *Backend) GetTd(blockHash common.Hash) (*big.Int, error) {
 }
 
 // CurrentBlock returns the current block
-func (b *Backend) CurrentBlock() *types.Block {
-	block, _ := b.BlockByNumber(context.Background(), rpc.LatestBlockNumber)
-	return block
+func (b *Backend) CurrentBlock() (*types.Block, error) {
+	block, err := b.BlockByNumber(context.Background(), rpc.LatestBlockNumber)
+	return block, err
 }
 
 // BlockByNumberOrHash returns block by number or hash