ethclient: add 'finalized' and 'safe' block number support (ethereum#25580)

Author: rachel-bousfield

ethclient/ethclient.go

@@ -570,6 +570,14 @@ func toBlockNumArg(number *big.Int) string {
 	if number.Cmp(pending) == 0 {
 		return "pending"
 	}
+	finalized := big.NewInt(int64(rpc.FinalizedBlockNumber))
+	if number.Cmp(finalized) == 0 {
+		return "finalized"
+	}
+	safe := big.NewInt(int64(rpc.SafeBlockNumber))
+	if number.Cmp(safe) == 0 {
+		return "safe"
+	}
 	return hexutil.EncodeBig(number)
 }
 

ethclient/gethclient/gethclient.go

@@ -187,6 +187,14 @@ func toBlockNumArg(number *big.Int) string {
 	if number.Cmp(pending) == 0 {
 		return "pending"
 	}
+	finalized := big.NewInt(int64(rpc.FinalizedBlockNumber))
+	if number.Cmp(finalized) == 0 {
+		return "finalized"
+	}
+	safe := big.NewInt(int64(rpc.SafeBlockNumber))
+	if number.Cmp(safe) == 0 {
+		return "safe"
+	}
 	return hexutil.EncodeBig(number)
 }