Fix(engine-transactions): Prevent panic on empty input (#573)

engine-transactions/src/lib.rs

@@ -24,7 +24,9 @@ impl TryFrom<&[u8]> for EthTransactionKind {
  type Error = Error;
 
  fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
- if bytes[0] == eip_2930::TYPE_BYTE {
+ if bytes.is_empty() {
+ Err(Error::EmptyInput)
+ } else if bytes[0] == eip_2930::TYPE_BYTE {
  Ok(Self::Eip2930(eip_2930::SignedTransaction2930::decode(
  &Rlp::new(&bytes[1..]),
  )?))
@@ -181,6 +183,7 @@ impl NormalizedEthTransaction {
 #[cfg_attr(feature = "serde", derive(serde::Serialize))]
 pub enum Error {
  UnknownTransactionType,
+ EmptyInput,
  // Per the EIP-2718 spec 0xff is a reserved value
  ReservedSentinel,
  InvalidV,
@@ -200,6 +203,7 @@ impl Error {
  pub fn as_str(&self) -> &'static str {
  match self {
  Self::UnknownTransactionType => "ERR_UNKNOWN_TX_TYPE",
+ Self::EmptyInput => "ERR_EMPTY_TX_INPUT",
  Self::ReservedSentinel => "ERR_RESERVED_LEADING_TX_BYTE",
  Self::InvalidV => "ERR_INVALID_V",
  Self::EcRecover => "ERR_ECRECOVER",
@@ -244,3 +248,32 @@ fn vrs_to_arr(v: u8, r: U256, s: U256) -> [u8; 65] {
  result[64] = v;
  result
 }
+
+#[cfg(test)]
+mod tests {
+ use super::{Error, EthTransactionKind};
+ use crate::{eip_1559, eip_2930};
+
+ #[test]
+ fn test_try_parse_empty_input() {
+ assert!(matches!(
+ EthTransactionKind::try_from([].as_ref()),
+ Err(Error::EmptyInput)
+ ));
+
+ // If the first byte is present, then empty bytes will be passed in to
+ // the RLP parsing. Let's also check this is not a problem.
+ assert!(matches!(
+ EthTransactionKind::try_from([eip_1559::TYPE_BYTE].as_ref()),
+ Err(Error::RlpDecodeError(_))
+ ));
+ assert!(matches!(
+ EthTransactionKind::try_from([eip_2930::TYPE_BYTE].as_ref()),
+ Err(Error::RlpDecodeError(_))
+ ));
+ assert!(matches!(
+ EthTransactionKind::try_from([0x80].as_ref()),
+ Err(Error::RlpDecodeError(_))
+ ));
+ }
+}