@ganache/rlp

Recursive Length Prefix Encoding for Node.js.

Based on https://github.com/ethereumjs/rlp, with some additional optimizations for encoding:

function encodeRange<
  T extends EncodingInput | Readonly<EncodingInput>,
  Start extends RangeOf<T["length"]>
>(
  items: T,
  start: Start,
  length: Exclude<Remainders<T["length"], Start>, 0>
): { length: number; output: Buffer[] } {
  //...;
}

Begin RLP encoding of items, from start until length. Call RLP.digest to finish encoding.

Returns an object containing the total length of all data in the encoded parts, and output, an array of encoded Buffers.

function digest(ranges: Readonly<Buffer[]>[], length: number) {
  // ...
}

Finishes encoding started by encodeRange.

Returns a Buffer of encoded data.

Additional changes:

• minor optimisations to encode
• encode only accepts buffers or nested buffer arrays, strings, number, bigint, and BN support have been removed.

---

These changes enable encoding data in chunks, avoiding processing the same inputs multiple times in common scenarios withing Ganache. Example:

type EthereumRawTx = [
  nonce: Buffer,
  gasPrice: Buffer,
  gas: Buffer,
  to: Buffer,
  value: Buffer,
  data: Buffer,
  v: Buffer,
  r: Buffer,
  s: Buffer
];
// encode the first 6 entries
const partialRlp = encodeRange(raw, 0, 6);
// encode the last 3 entires
const signature = encodeRange(raw, 6, 3);
// combine all entries
const serialized = digest(
  [partialRlp.output, signature.output],
  partialRlp.length + signature.length
);
return {
  // computing the `from` address requires entries 0-6
  from: computeFromAddress(partialRlp, v.toNumber(), raw, chainId),
  // hash requires entries 0-9
  hash: Data.from(keccak(serialized), 32),
  // serialized uses all entries for storage/transmission
  serialized
};