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Solidity-RLP

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A solidity library for Ethereum's RLP decoding

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- Helper.sol
- Migrations.sol
- RLPReader.sol
- 1_initial_migration.js
- 2_initial_migration.js
- basic-tests.js
.gitattributes
.gitignore
.travis.yml
Changelog.md
LICENSE
package-lock.json
package.json
README.md
truffle-config.js

# Installation Guide

1. Get the code

git clone https://github.com/hamdiallam/Solidity-RLP

Downloads the entire project code from GitHub to your computer.

cd Solidity-RLP

Moves into the project folder you just downloaded.

2. Node.js

Easy Recommended

Prerequisites

Git Needed to download the project code from GitHub.
Node.js Node.js must be installed to use npm. The LTS version is recommended.

npm install

Downloads and installs the libraries listed in package.json.

npm start

Starts the development/run server.

✅ After running the command, open the address shown in the terminal (usually something like http://localhost:3000) in your browser.

// repository documentation

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# RLP decoder/reader
[![Build Status](https://travis-ci.com/hamdiallam/Solidity-RLP.svg?branch=master)](https://travis-ci.com/hamdiallam/Solidity-RLP)
Currently supports solidity **v0.6.0**
> Please raise issues for bugs, and solidity updates. I will be monitoring the solidity changelogs and updating this package accordingly

## Installation
1. `npm install solidity-rlp` in the project directory. Make sure to install through npm for prompt updates!
2. `import "solidity-rlp/contracts/RLPReader.sol"` in the desired smart contract.

_See the example smart contract below_

## Usage
The reader contract provides an interface to first take RLP encoded bytes and convert them into
an internal data structure, `RLPItem` through the function, `toRlpItem(bytes)`. This data structure can then be
destructured into the desired data types.

Transformations (all take an RLPItem as an arg):
1. `isList(RLPItem) bool` : inidicator if the encoded data is a list
2. `toList(RLPItem) RLPItem[]` : returns a list of RLPItems
3. `toBytes(RLPItem) bytes` : returns the payload in bytes
4. `toAddress(RLPItem) address` : returns the encoded address. Must be exactly 20 bytes.
5. `toUint(RLPItem) uint` : returns the encoded uint. Enforced data is capped to 32 bytes.
6. `toUintStrict(RLPItem) uint` : returns the encoded uint. Encoded data must be padded to 32 bytes.
7. `toBoolean(RLPItem) bool` : returns the encoded boolean
8. `toRlpBytes(RLPItem) bytes ` : returns the raw rlp encoded byte form
9. `rlpLen(RLPItem) uint` : returns the byte length of the rlp item
10. `payloadLocation(RLPItem) (uint memPtr, uint len)` : returns the memory pointer and byte length of the data payload
11. `payloadLen(RLPItem) uint` : returns the byte length of the data payload; an alias to payloadLocation(item)[1]

**Note**: The reader contract only provides only these conversion functions. All other solidity data types can be derived from
this base. For example, a `bytes32` encoded data type is equivalent to `bytes32(toUint(RLPItem))`. Start with a uint and convert from there.
A string can be retrieved by `string(toBytes(RLPItem))`. See example for a sample smart contract.

Iteration functions:
1. `iterator(RLPItem) Iterator` : returns an `Iterator` over the RLPItem. RLPItem must be an encoded list
2. `hasNext(Iterator) bool` : indicator if there is another item to iterate on
3. `next(Iterator) RLPItem` : returns the next `RLPItem` in the iterator

Utility functions:
1. `rlpBytesKeccak256(RLPItem) bytes32` : returns keccak256 hash of RLP encoded bytes. A cheap version
   of `keccak256(toRlpBytes(RLPItem))` that avoids copying memory.
2. `payloadKeccak256(RLPItem) bytes32` : returns keccak256 hash of the item payload. A cheap
   version of `keccak256(toBytes(RLPItem))` that avoids copying memory.

## Example
```solidity
import "solidity-rlp/contracts/RLPReader.sol"

contract SomeContract {
    
    // optional way to attach library functions to these data types.
    using RLPReader for RLPReader.RLPItem;
    using RLPReader for RLPReader.Iterator;
    using RLPReader for bytes;

// lets assume that rlpBytes is an encoding of [[1, "nested"], 2, 0x<Address>]
    function someFunctionThatTakesAnEncodedItem(bytes memory rlpBytes) public {
        RLPReader.RLPItem[] memory ls = rlpBytes.toRlpItem().toList(); // must convert to an rlpItem first!

RLPReader.RLPItem memory item = ls[0]; // the encoding of [1, "nested"].
        item.toList()[0].toUint(); // 1
        string(item.toList()[1].toBytes()); // "nested"

ls[1].toUint(); // 2
        ls[2].toAddress(); // 0x<Address>
    }

// lets assume rlpBytes is an encoding of [["sublist"]]
    function someFunctionThatDemonstratesIterators(bytes memory rlpBytes) public {
        RLPReader.Iterator memory iter = rlpBytes.toRlpItem().iterator();
        RLPReader.Iterator memory subIter = iter.next().iterator();

// iter.hasNext() == false
        // string(subIter.next().toBytes()) == "sublist"
        // subIter.hasNext() == false
    }
}
```

## Tests
1. `git clone https://github.com/hamdiallam/solidity-rlp && cd solidity-rlp`
2. `npm install`
3. `npm install -g truffle ganache-cli` installed globally for the dev envirnoment
4. `ganache-cli` run in a background process or seperate terminal window.
4. `truffle compile && truffle test`

## Audits

### 2021-05: MixBytes

Version 2.0.5 of this library (commit [`a283779`](https://github.com/hamdiallam/Solidity-RLP/tree/a2837797e4da79070701339947f32f5725e08b56)) was audited by [MixBytes](https://github.com/mixbytes) as part of the Lido stETH price oracle audit.

Summary:

- Total Issues: 1 (1 Fixed)
- Critical Issues: 0 (0 Fixed)
- Major Issues: 0 (0 Fixed)
- Warning Issues: 0 (0 No issue)
- Comment Risk Issues: 1 (1 Fixed)

See [the full report](https://github.com/lidofinance/audits/blob/main/MixBytes%20stETH%20price%20oracle%20Security%20Audit%20Report%2005-2021.pdf) for details.